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A new relaxion mechanism is proposed where a small electroweak scale is preferably selected earlier than the larger one due to a potential instability, which is different from previously proposed stopping mechanisms by either Hubble friction from an increasing periodic barrier or thermal friction from gauge boson production. The sub-Planckian field excursion of an axion can be achieved without violating the bound on the e-folding number from a quantum gravity perspective; our relaxion can be identified as a QCD axion, preserving the Peccei-Quinn solution to the strong CP problem as well as making up all the cold dark matter in our current Universe. [ABSTRACT FROM AUTHOR]

In the present paper, we construct spontaneously scalarized rotating black hole solutions in dynamical Chern-Simons (dCS) gravity by following the scalar field evolution in the decoupling limit. For the range of parameters where the Kerr black hole becomes unstable within dCS gravity, the scalar field grows exponentially until it reaches an equilibrium configuration that is independent of the initial perturbation. Interestingly, the Z2 symmetry of the scalar field is broken, and a strong maximum around only one of the rotational axes can be observed. The black hole scalar charge is calculated for two coupling functions, suggesting that the main observations would remain qualitatively correct even if one considers coupling functions/coupling parameters producing large deviations from the Kerr solution beyond the decoupling limit approximation. [ABSTRACT FROM AUTHOR]

In a previous paper, we considered the motion of massive spinning test particles in the "pole-dipole" approximation, as described by the Mathisson-Papapetrou-Dixon (MPD) equations and examined its properties in dependence on the spin supplementary condition. We decomposed the equations in the orthonormal tetrad based on the timelike vector fixing the spin condition and on the corresponding spin, while representing the curvature in terms of the Weyl scalars obtained in the Newman-Penrose null tetrad naturally associated with the orthonormal one; the projections thus obtained did not contain the Weyl scalars Ψ0 and Ψ4. In the present paper, we choose the interpretation tetrad in a different way, attaching it to the tangent uμ of the worldline representing the history of the spinning body. Actually two tetrads are suggested, both given "intrinsically" by the problem and each of them incompatible with one specific spin condition. The decomposition of the MPD equation, again supplemented by writing its right-hand side in terms of the Weyl scalars, is slightly less efficient than in the massive case, because uμ cannot be freely chosen (in contrast to Vμ) and so the uμ-based tetrad is less flexible. In the second part of this paper, a similar analysis is performed for massless spinning particles; in particular, a certain intrinsic interpretation tetrad is again found. The respective decomposition of the MPD equation of motion is considerably simpler than in the massive case, containing only Ψ1 and Ψ2 scalars and not the cosmological constant. An option to span the spin-bivector eigenplane, besides the worldline null tangent, by a main principal null direction of the Weyl tensor can lead to an even simpler result. [ABSTRACT FROM AUTHOR]

In a recent paper [M. Assanioussi, A. Dapor, and J. Lewandowski, Phys. Lett. B 751, 302 (2015)] a general mechanism for the emergence of cosmological spacetime geometry from a quantum gravity setting was devised and a departure from standard dispersion relations for an elementary particle was predicted. We elaborate here on this approach extending the results obtained in that paper and showing that generically such a framework will not lead to higher order modified dispersion relations in the matter sector. Furthermore, we shall discuss possible phenomenological constraints to this scenario showing that spacetime will have to be classical to a very high degree by now in order to be consistent with current observations. [ABSTRACT FROM AUTHOR]

The rare kaon decays K → πl+l- and K → πvv are flavor changing neutral current (FCNC) processes and hence promising channels with which to probe the limits of the standard model and to look for signs of new physics. In this paper we demonstrate the feasibility of lattice calculations of K → πl+l- decay amplitudes for which long-distance contributions are very significant. We show that the dominant finitevolume corrections (those decreasing as powers of the volume) are negligibly small and that, in the fourflavor theory, no new ultraviolet divergences appear as the electromagnetic current J and the effective weak Hamiltonian Hw approach each other. In addition, we demonstrate that one can remove the unphysical terms which grow exponentially with the range of the integration over the time separation between J and Hw. We will now proceed to exploratory numerical studies with the aim of motivating further experimental measurements of these decays. Our work extends the earlier study by Isidori et al. [ 1 ] which focused largely on the renormalization of ultraviolet divergences. In a companion paper [2] we discuss the evaluation of the long-distance contributions to K →πvv decays; these contributions are expected to be at the level of a few percent for K+ decays. [ABSTRACT FROM AUTHOR]

In the present paper the electrostatics of charges in nonrotating BTZ black hole and wormhole spacetimes is studied. Our attention is focused on the self-force of a point charge in the geometry, for which a regularization prescription based on the Haddamard Green function is employed. The differences between the self-force in both cases is a theoretical experiment for distinguishing both geometries, which otherwise are locally indistinguishable. This idea was applied before to four and higher-dimensional black holes by the present and other authors. However, the particularities of the BTZ geometry makes the analysis considerable more complicated than those. First, the BTZ spacetimes are not asymptotically flat but instead asymptotically AdS. In addition, the relative distance d(r, r + 1) between two particles located at a radius r and r + 1 in the geometry tends to zero when r → ∞. This behavior, which is radically different in a flat geometry, changes the analysis of the asymptotic conditions for the electrostatic field. The other problem is that there exist several regularization methods other than the one we are employing, and there does not exist a proof in three dimensions that they are equivalent. However, we focus on the Haddamard method and obtain an expression for the hypothetical self-force in series, and the resulting expansion is convergent to the real solution. We suspect that the convergence is not uniform, and furthermore there are no summation formulas at our disposal. It appears, for points that are far away from the black hole the calculation of the Haddamard self-force requires higher-order summation. These subtleties are carefully analyzed in the paper, and it is shown that they lead to severe problems when calculating the Haddamard self-force for asymptotic points in the geometry. [ABSTRACT FROM AUTHOR]

We show that, in contrast to known results in the massive case, a minimally gauged massless Rarita-Schwinger field yields a consistent classical theory, with a generalized fermionic gauge invariance realized as a canonical transformation. To simplify the algebra, we study a two-component left chiral reduction of the massless theory. We formulate the classical theory in both Lagrangian and Hamiltonian form for a general non-Abelian gauging and analyze the constraints and the Rarita-Schwinger gauge invariance of the action. An explicit wave front calculation for Abelian gauge fields shows that wavelike modes do not propagate with superluminal velocities. An analysis of Rarita-Schwinger spinor scattering from gauge fields shows that adiabatic decoupling fails in the limit of zero gauge field amplitude, invalidating various "no-go" theorems based on "on-shell" methods that claim to show the impossibility of gauging Rarita-Schwinger fields. Quantization of Rarita-Schwinger fields, using many formulas from this paper, is taken up in the following paper. [ABSTRACT FROM AUTHOR]

We investigate the inner structure of a general SU(2) [naturally including SO(3)] symmetry system--the fermion-gauge field interaction system--and achieve naturally a set of gauge-invariant spin and orbital angular momentum operators of fermion and gauge fields by Noether's theorem in general field theory. Some new relations concerning non-Abelian field strengths are discovered, e.g., the covariant transverse condition, covariant parallel condition (i.e., non-Abelian divergence, non-Abelian curl), and simplified SU(2) Coulomb theorem. And we show that the condition that Chen et al. obtained to construct their gauge-invariant angular momentum operators is a result of some fundamental equations in the general field theory. The results obtained in this paper present a new perspective for looking at the overall structure of the gauge field, and provide a new viewpoint to the final resolution of the nucleon spin crisis in the general field theory. Especially, the achieved theory in this paper can calculate the strong interactions with isospin symmetry and solves the serious problem without gauge-invariant angular momenta in strong interaction systems with isospin symmetry, and then the achieved predictions in the calculations can be exactly measured by particle physics experiments due to their gauge invariant properties. [ABSTRACT FROM AUTHOR]

A real antisymmetric tensor field was introduced to realize a holographic magnetic ordered phase in our previous papers. However, a more careful analysis shows there is a vector ghost in the model. In this paper we present a modified Lagrangian density for the antisymmetric tensor, which is ghost free and causality is well defined, and keeps all the significant results in the original model qualitatively. We show this modified Lagrangian density could come from the dimensional compactification of p-form field in string/M theory. For static curved space-time, we also prove that this modified model is ghost free and does not violate causality. This new model offers a solid foundation for the application of antisymmetric tensor field in holographic duality, especially for the spontaneous magnetization. [ABSTRACT FROM AUTHOR]

The semiclassical operator method of Baier and Katkov allows one to obtain the spectrum of synchrotron radiation in a way similar to the classical derivation but which is fully valid also in the quantum case of very strong electromagnetic fields. In the usual calculation the extension of the field is taken to be infinite. In this paper we apply a numerical routine based on the semiclassical operator method to the case of a constant field but with a finite extension. For large extensions of the field one obtains the usual result of quantum synchrotron radiation, while in the limit of small extension of the field one obtains a spectrum resembling that of bremsstrahlung. We derive a formula for the radiation spectrum in this limit. In the transition toward shorter field extensions one finds that the power-spectrum increases for soft photons and slightly diminishes for harder photons. It is found that in the classical case the total power emitted decreases as the field extension decreases while in the quantum case the total power emitted is first increased and then decreases. Such an effect could be important for future e+e- colliders such as the ILC or CLIC where the dominant energy and luminosity loss is due to synchrotron radiation by an e-/e+ in the field of the opposing bunch, often termed "beamstrahlung." In this paper we also discuss how these effects, in the quantum case could be measured in an experiment using thin aligned single crystals and high energy electrons available at e.g. the CERN SPS North Area, and in the classical case could already be relevant at existing accelerators with conventional magnets providing the electromagnetic field. [ABSTRACT FROM AUTHOR]

Space-borne gravitational wave detectors, such as (e)LISA, are designed to operate in the low-frequency band (mHz to Hz), where there is a variety of gravitational wave sources of great scientific value [arXiv: 1305.5720 and S. Babak et al., Classical Quantum Gravity 28, 114001 (2011)]. To achieve the extraordinary sensitivity of these detectors, the precise synchronization of the clocks on the separate spacecraft and the accurate determination of the interspacecraft distances are important ingredients. In our previous paper [Y. Wang et al., Phys. Rev. D 90, 064016 (2014)], we have described a hybrid-extend Kalman filter with a full state vector to do this job. In this paper, we explore several different state vectors and their corresponding (phenomenological) dynamic models to reduce the redundancy in the full state vector, to accelerate the algorithm, and to make the algorithm easily extendable to more complicated scenarios. [ABSTRACT FROM AUTHOR]

We consider a class of Lorentz-violating theories of gravity involving a timelike unit vector field (the aether) coupled to a metric, two examples of which are Einstein-aether theory and Horava gravity. The action always includes the Ricci scalar of the metric and the invariants quadratic in covariant derivatives of the aether, but the theories differ in how the aether is constructed from other fields, and whether those fields are varied in the action. Fields that are not varied define background structures breaking diffeomorphsim invariance, including threadings, folations, and clocks, which generally produce novel degrees of freedom arising from the violation of what would otherwise be initial value constraints. The principal aims of this paper are to survey the nature of the theories that arise and to understand the consequences of breaking diffeomorphism invariance in this setting. In a companion paper [A. J. Speranza, arXiv:1504.03305], we address some of the phenomenology of the "ponderable aether" case in which the presence of a background clock endows the aether with a variable internal energy density that behaves in some respects like dark matter. [ABSTRACT FROM AUTHOR]

This is the first of two papers which study the behavior of the SU(2) holonomies of canonical quantum gravity, when they are acted upon by a unidirectional, plane gravity wave. The present paper constructs a model based on holonomies and fluxes having support on a lattice (LHF denotes lattice-holonomy flux, rather than loop quantum gravity, since there are no loops). Initially, the flux-holonomy variables are treated as classical, commuting functions rather than quantized operators, in a limit where variation from vertex to vertex is small and fields are weak. We impose symmetries and fix gauges at the classical level. Despite the weakness of the fields, the field equations are not linear. Also, the theory can be quantized, and the expectation values of the quantum operators behave like their classical analogs. Exact LHF theories may be either local or nonlocal. The present paper argues that a wide class of nonlocal theories share nonlocal features which survive to the semiclassical limit, and these nonlocal features are included in the nearclassical limit studied here. An appendix computes the surface term required when the propagation direction is the real line rather than S1. Paper II introduces coherent states, constructs a damped sine wave solution to the model, and solves for the behavior of the holonomies in the presence of the wave. [ABSTRACT FROM AUTHOR]

Using a generalization of the Madelung transformation, we derive the hydrodynamic representation of the Klein-Gordon-Einstein equations in the weak field limit. We consider a complex self-interacting scalar field with a λ|φ|4 potential. We study the evolution of the spatially homogeneous background in the fluid representation and derive the linearized equations describing the evolution of small perturbations in a static and in an expanding Universe. We compare the results with simplified models in which the gravitational potential is introduced by hand in the Klein-Gordon equation, and assumed to satisfy a (generalized) Poisson equation. Nonrelativistic hydrodynamic equations based on the Schrödinger-Poisson equations or on the Gross-Pitaevskii-Poisson equations are recovered in the limit c →+∞. We study the evolution of the perturbations in the matter era using the nonrelativistic limit of our formalism. Perturbations whose wavelength is below the Jeans length oscillate in time while perturbations whose wavelength is above the Jeans length grow linearly with the scale factor as in the cold dark matter model. The growth of perturbations in the scalar field model is substantially faster than in the cold dark matter model. When the wavelength of the perturbations approaches the cosmological horizon (Hubble length), a relativistic treatment is mandatory. In that case, we find that relativistic effects attenuate or even prevent the growth of perturbations. This paper exposes the general formalism and provides illustrations in simple cases. Other applications of our formalism will be considered in companion papers. [ABSTRACT FROM AUTHOR]

Weak gravitational lensing allows one to reconstruct the spatial distribution of the projected mass density across the sky. These "mass maps" provide a powerful tool for studying cosmology as they probe both luminous and dark matter. In this paper, we present a weak lensing mass map reconstructed from shear measurements in a 139 deg² area from the Dark Energy Survey (DES) science verification data. We compare the distribution of mass with that of the foreground distribution of galaxies and clusters. The overdensities in the reconstructed map correlate well with the distribution of optically detected clusters. We demonstrate that candidate superclusters and voids along the line of sight can be identified, exploiting the tight scatter of the cluster photometric redshifts. We cross-correlate the mass map with a foreground magnitude-limited galaxy sample from the same data. Our measurement gives results consistent with mock catalogs from V-body simulations that include the primary sources of statistical uncertainties in the galaxy, lensing, and photo-z catalogs. The statistical significance of the cross-correlation is at the 6.8σ level with 20 arcminute smoothing. We find that the contribution of systematics to the lensing mass maps is generally within measurement uncertainties. In this work, we analyze less than 3% of the final area that will be mapped by the DES; the tools and analysis techniques developed in this paper can be applied to forthcoming larger data sets from the survey. [ABSTRACT FROM AUTHOR]

In this paper we study the equilibrium configurations of anisotropic self-gravitating fermions, by extending to general relativity the solutions obtained in a previous paper. This treatment also generalizes to anisotropic systems the relativistic self-gravitating Fermi gas model, by considering different degrees of anisotropy. We discuss some important characteristics of the models and the obtained density profiles, and generalize the relation between the anisotropy and the mass of particles in the relativistic regime. These relativistic models may also be applied to the study of superdense neutron stars with anisotropic pressure or super-Chandrasekhar white dwarfs generated by the presence of a magnetic field. [ABSTRACT FROM AUTHOR]

Over the past three decades, considerable effort has been devoted to studying the rich and diverse phenomenologies of heterotic strings exhibiting spacetime supersymmetry. Unfortunately, during this same period, there has been relatively little work studying the phenomenologies associated with their nonsupersymmetric counterparts. The primary reason for this relative lack of attention is the fact that strings without spacetime supersymmetry are generally unstable, exhibiting large one-loop dilaton tadpoles. In this paper, we demonstrate that this hurdle can be overcome in a class of tachyon-free four-dimensional string models realized through coordinate-dependent compactifications. Moreover, as we shall see, it is possible to construct models in this class whose low-lying states resemble the Standard Model (or even potential unified extensions thereof)--all without any light superpartners, and indeed without supersymmetry at any energy scale. The existence of such models thus opens the door to general studies of nonsupersymmetric string phenomenology, and in this paper we proceed to discuss a variety of theoretical and phenomenological issues associated with such nonsupersymmetric strings. On the theoretical side, we discuss the finiteness properties of such strings, the general characteristics of their mass spectra, the magnitude and behavior of their one-loop cosmological constants, and their interpolation properties. By contrast, on the phenomenological side, the properties we discuss are more model-specific and include their construction techniques, their natural energy scales, their particle and charge assignments, and the magnitudes of their associated Yukawa couplings and scalar masses. [ABSTRACT FROM AUTHOR]

Lorentz violation is a candidate quantum-gravity signal, and the Standard-Model Extension (SME) is a widely used parametrization of such a violation. In the gravitational SME sector, there is an elusive coefficient for which no effects have been found. This is known as the t puzzle and, to date, it has no compelling explanation. This paper analyzes whether there is a fundamental explanation for the t puzzle. To tackle this question, several approaches are followed. Mainly, redefinitions of the dynamical fields are studied, showing that other SME coefficients can be moved to nongravitational sectors. It is also found that the gravity SME sector can be consistently treated à la Palatini, and that, in the presence of spacetime boundaries, it is possible to correct its action to get the desired equations of motion. Moreover, through a reformulation as a Lanczos-type tensor, some problematic features of the t term, which should arise at the phenomenological level, are revealed. The most important conclusion of the paper is that there is no evidence of a fundamental explanation for the t puzzle, suggesting that it may be linked to the approximations taken at the phenomenological level. [ABSTRACT FROM AUTHOR]

This paper studies jetlike electromagnetic configurations surrounding a slowly spinning black-hole immersed in a uniformly magnetized force-free plasma. In the first part of this paper, we present a family of stationary solutions that are jet capable. While these solutions all satisfy the force-free equations and the appropriate boundary conditions, our numerical experiments show a unique relaxed state starting from different initial data, and so one member of the family is likely preferred over the others. In the second part of this paper, we analyze the perturbations of this family of jetlike solutions, and show that the perturbative modes exhibit a similar split into the trapped and traveling categories previously found for perturbed Blandford-Znajek solutions. In the eikonal limit, the trapped modes can be identified with the fast magnetosonic waves in the force-free plasma and the traveling waves are essentially the Alfvén waves. Moreover, within the scope of our analysis, we have not seen signs of unstable modes at the light-crossing time scale of the system, within which the numerical relaxation process occurs. This observation disfavors mode instability as the selection mechanism for picking out a preferred solution. Consequently, our analytical study is unable to definitively select a particular solution out of the family to serve as the aforementioned preferred final state. This remains an interesting open problem. [ABSTRACT FROM AUTHOR]

Certain physical quantities that characterize neutron stars and quark stars (e.g. their mass, spin angular momentum, and quadrupole moment) have recently been found to be interrelated in a manner that is approximately insensitive to their internal structure. Such approximately universal relations are useful to break degeneracies in data analysis and model selection for future radio, x-ray, and gravitational wave observations. Although the pressure inside compact stars is most likely nearly isotropic, certain scenarios have been put forth that suggest otherwise, for example due to magnetic fields or phase transitions in their interior. We investigate here whether pressure anisotropy affects the approximate universal relations and, if so, whether it prevents their use in future astrophysical observations. We achieve this by numerically constructing slowly rotating and tidally deformed, anisotropic, compact stars in general relativity to third order in stellar rotation relative to the mass shedding limit. We adopt simple models for pressure anisotropy where the matter stress-energy tensor is diagonal for a spherically symmetric spacetime but the tangential pressure differs from the radial one. We find that the equation-of-state variation increases as one increases the amount of anisotropy, but within the anisotropy range studied in this paper (motivated from anisotropy due to crystallization of the core and pion condensation), anisotropy affects the universal relations only weakly. The relations become less universal by a factor of 1.5-3 relative to the isotropic case when anisotropy is maximal, but even then they remain approximately universal to 10%. We find evidence that this increase in variability is strongly correlated to an increase in the eccentricity variation of isodensity contours, which provides further support for the emergent approximate symmetry explanation of universality. Whether one can use universal relations in actual observations ultimately depends on the currently unknown amount of anisotropy inside stars, but within the range studied in this paper, anisotropy does not prevent the use of universal relations in gravitational wave astrophysics or in experimental relativity. We provide an explicit example of the latter by simulating a binary pulsar/gravitational wave test of dynamical Chern-Simons gravity with anisotropic neutron stars. The increase in variability of the universal relations due to pressure anisotropy could affect their use in future x-ray observations of hot spots on rotating compact stars. Given expected observational uncertainties, however, the relations remain sufficiently universal for use in such observations if the anisotropic modifications to the moment of inertia and the quadrupole moment are less than 10% of their isotropic values. [ABSTRACT FROM AUTHOR]

In a previous paper [S.?Q. Wu, Phys. Rev. D 83, 121502(R) (2011)], a new kind of metric ansatz was found to fairly describe all already-known black hole solutions in the ungauged Kaluza-Klein (KK) supergravity theories. That metric ansatz somewhat resembles the famous Kerr-Schild (KS) form, but it is different from the KS one in two distinct aspects. That is, apart from a global conformal factor, the metric ansatz can be written as a vacuum background spacetime plus a "perturbation" modification term, the latter of which is associated with a timelike geodesic vector field rather than a null geodesic congruence in the usual KS ansatz. Replacing the flat vacuum background metric by the (anti-)de Sitter [(A)dS] spacetime, the general rotating charged KK-(A)dS black hole solutions in all higher dimensions have been successfully constructed and put into a unified form. In this paper, we shall study this novel metric ansatz in detail, aiming at achieving some inspiration as to the construction of rotating charged AdS black holes with multiple charges in other gauged supergravity theories. We find that the traditional perturbation expansion method often successfully used in the KS form is no longer useful in our new ansatz, since here no good parameter can be chosen as a suitable perturbation indicator. In order to investigate the metric properties of the general KK-AdS solutions, in this paper we devise a new effective method, dubbed the background metric expansion method, which can be thought of as a generalization of the perturbation expansion method, to deal with the Lagrangian and all equations of motion. In addition to two previously known conditions, namely the timelike and geodesic properties of the vector, we get three additional constraints via contracting the Maxwell and Einstein equations once or twice with this timelike geodesic vector. In particular, we find that these are a simpler set of sufficient conditions to determine the vector and the dilaton scalar around the background metric, which is helpful in obtaining new exact solutions. With these five simpler equations in hand, we rederive the general rotating charged KK-(A)dS black hole solutions with spherical horizon topology and obtain new solutions with planar topology in all dimensions. It turns out that the overall calculations in finding the solution to the KK gauged supergravity can be reduced considerably, compared to the previous process, by directly solving all the field equations. It is then shown that the rotating charged KK-AdS black hole solutions can be further generalized by introducing one or two arbitrary constants, while the black hole solutions with the planar AdS background metric in all higher dimensions are newly obtained. [ABSTRACT FROM AUTHOR]

Computation of the renormalized stress-energy tensor is the most serious obstacle in studying the dynamical, self-consistent, semiclassical evaporation of a black hole in 4D. The difficulty arises from the delicate regularization procedure for the stress-energy tensor, combined with the fact that in practice the modes of the field need to be computed numerically. We have developed a new method for numerical implementation of the point-splitting regularization in 4D, applicable to the renormalized stress-energy tensor as well as to ⟨ϕ²⟩ren, namely the renormalized ⟨ϕ²⟩. So far we have formulated two variants of this method: t-splitting (aimed for stationary backgrounds) and angular splitting (for spherically symmetric backgrounds). In this paper we introduce our basic approach, and then focus on the t-splitting variant, which is the simplest of the two (deferring the angular-splitting variant to a forthcoming paper). We then use this variant, as a first stage, to calculate ⟨ϕ²⟩ren in Schwarzschild spacetime, for a massless scalar field in the Boulware state. We compare our results to previous ones, obtained by a different method, and find full agreement. We discuss how this approach can be applied (using the angular-splitting variant) to analyze the dynamical self-consistent evaporation of black holes. [ABSTRACT FROM AUTHOR]

White dwarfs (WD) capture dark matter (DM) as they orbit within their host halos. These captured particles may subsequently annihilate, heating the stellar core and preventing the WD from cooling. The potential wells of WDs are considerably deeper and core temperatures significantly cooler than those of main sequence stars. Consequently, DM evaporation is less important in WDs and DM with masses Mχ≳100 keV, and annihilation cross sections orders of magnitude below the canonical thermal cross section (σav≳10−46 cm³/s) can significantly alter WD cooling in particular astrophysical environments. We consider WDs in globular clusters (GCs) and dwarf galaxies. If the parameters of the DM particle are known, then the temperature of the coolest WD in a GC can be used to constrain the DM density of the cluster's halo (potentially even ruling out the presence of a halo if the inferred density is of order the ambient Galactic density). Recently, several direct detection experiments have seen signals whose origins might be due to low mass DM. In this paper, we show that if these claims from CRESST, DAMA, CDMS-Si, and CoGeNT could be interpreted as DM, then observations of NGC 6397 limit the fraction of DM in that cluster to be fDM≲10−3. This would be an improvement over existing constraints of 3 orders of magnitude and would clearly rule out a significant DM halo for this cluster. More generally, we show how such observations constrain combinations of DM and GC properties. Building on previous work, we also show how observations of WDs in dwarf galaxies, such as Segue I, can provide novel constraints on low-mass DM or DM with very low contemporary annihilation cross sections as may be realized in models in which s-wave annihilation is suppressed and p-wave annihilation dominates. This paper provides further motivation for high-quality observations of stellar populations as a probe of dark matter. [ABSTRACT FROM AUTHOR]

In the presence of a light weakly interacting massive particle (WIMP) with mass mx ≲ 30 MeV, there are degeneracies among the nature of the WIMP (fermion or boson), its couplings to the standard model particles (to electrons, positrons, and photons, or only to neutrinos), its mass mx, and the number of equivalent (additional) neutrinos, ΔNv. These degeneracies cannot be broken by the cosmic microwave background (CMB) constraint on the effective number of neutrinos, Neff. However, since big bang nucleosynthesis (BBN) is also affected by the presence of a light WIMP and equivalent neutrinos, complementary BBN and CMB constraints can help to break some of these degeneracies. In a previous paper [K. M. Nollett and G. Steigman, Phys. Rev. D 89, 083508 (2014)] the combined BBN and Planck [P. A. R. Ade et al. (Planck Collaboration), Astron. Astrophys. 571, A16 (2014)] CMB constraints were used to explore the allowed ranges for mx ΔNv. and Neff in the case where the light WIMPs annihilate electromagnetically (EM) to photons and/or e± pairs. In this paper the BBN predictions for the primordial abundances of deuterium and 4He (along with ³He and 7Li) in the presence of a light WIMP that only couples (annihilates) to neutrinos [either standard model (SM) only or both SM and equivalent] are calculated. Recent observational estimates of the relic abundances of D and 4He are used to limit the light WIMP mass, the number of equivalent neutrinos, the effective number of neutrinos, and the present Universe baryon density (ΩBh²). Allowing for a neutrino coupled light WIMP and ΔNv. equivalent neutrinos, the combined BBN and CMB data provide lower limits to the WIMP mass that depend very little on the nature of the WIMP (Majorana or Dirac fermion, real or complex scalar boson), with a best fit mx ≳ 35 MeV, equivalent to no light WIMP at all. The analysis here excludes all neutrino coupled WIMPs with masses below a few MeV, with specific limits varying from 4 to 9 MeV depending on the nature of the WIMP. In the absence of a light WIMP (either EM or neutrino coupled), BBN alone prefers ΔNv= 0.50 ± 0.23, favoring neither the absence of equivalent neutrinos (ΔNv = 0), nor the presence of a fully thermalized sterile neutrino (ΔNv = 1). This result is consistent with the CMB constraint, Neff = 3.30 ± 0.27 [1], constraining "new physics" between BBN and recombination. Combining the BBN and CMB constraints gives ΔNv = 0.35 ± 0.16 and Neff = 3.40 ± 0.16. As a result, while BBN and the CMB combined require ΔNv ≥ 0 at ~98% confidence, they disfavor ΔNv ≥ 1 at > 99% confidence. Adding the possibility of a neutrino-coupled light WIMP extends the allowed range slightly downward for ΔNv, and slightly upward for Neff simultaneously, while leaving the best-fit values unchanged. [ABSTRACT FROM AUTHOR]

In this paper we proposed a solution to the long-standing problem of the color glass condensate(CGC)/ saturation approach: the powerlike fall of the scattering amplitudes at large b. This decrease leads to the violation of the Froissait theorem and makes the approach theoretically inconsistent. We showed in the paper that the sum of the pion loops results in the exponential fall of the scattering amplitude at large impact parameters and in the restoration of the Froissart theorem. [ABSTRACT FROM AUTHOR]

In a recent paper [P. Wang and X.-G. Wang, Phys. Rev. Lett. 111, 042002 (2013)], the charmonium state X(3872) is studied in the framework of an effective field theory. In that work it is claimed that (i) the one-pion exchange (OPE) alone provides sufficient binding to produce the X as a shallow bound state at the D0D*0 threshold, (ii) short-range dynamics (described by a contact interaction) provides only moderate corrections to the OPE, and (iii) the X-pole disappears as the pion mass is increased slightly and therefore the X should not be seen on the lattice, away from the pion physical mass point, if it were a molecular state. In this paper we demonstrate that the results of P. Wang and X.-G. Wang suffer from technical as well as conceptual problems and therefore do not support the conclusions drawn by the authors. [ABSTRACT FROM AUTHOR]

We generalize the ordinary Wess-Zumino model to the bosonic-fermionic noncommutative (BFNC) superspace and study its renormalization. In our previous work that can be regarded as the key foundation of the present paper, we have proved that the BFNC Wess-Zumino model with the real mass and interacting constant is one-loop renormalizable up to the second order of BFNC parameters. Based on the result obtained, in the present paper we modify the one-loop renormalizable BFNC Wess-Zumino model by generalizing the mass and interacting constant to complex numbers, introduce the U(1)R R symmetry and U(1)Φ flavor symmetry in the modified model, analyze possible divergent operators in the effective action of the modified model by using the dimensional analysis method, and further give a new BFNC Wess-Zumino model that is renormalizable at all loops still up to the second order of BFNC parameters by imposing symmetries rather than doing a direct perturbative investigation. [ABSTRACT FROM AUTHOR]

In a recent paper we showed that in shift-symmetric Horndeski theory the scalar field is forced to obtain a nontrivial configuration in black hole spacetimes, unless a linear coupling with the Gauss-Bonnet invariant is tuned away. As a result, black holes generically have hair in this theory. In this companion paper, we first review our argument and discuss it in more detail. We then present actual black hole solutions in the simplest case of a theory with the linear scalar-Gauss-Bonnet coupling. We generate exact solutions numerically for a wide range of values of the coupling and also construct analytic solutions perturbatively in the small-coupling limit. Comparison of the two types of solutions indicates that nonlinear effects that are not captured by the perturbative solution lead to a finite area, as opposed to a central, singularity. Remarkably, black holes have a minimum size, controlled by the length scale associated with the scalar-Gauss-Bonnet coupling. We also compute some phenomenological observables for the numerical solution for a wide range of values of the scalar-Gauss-Bonnet coupling. Deviations from the Schwarzschild geometry are generically very small. [ABSTRACT FROM AUTHOR]

We evaluate one-loop quantum gravity corrections to the conformally coupled (CC) scalar self-mass-squared on a locally de Sitter background. In this paper we consider only the conformal-conformal interaction part of the self-mass-squared. This complements the minimal-minimal part worked out in the previous paper [E. O. Kahya and R. P. Woodard, Phys. Rev. D 76, 124005 (2007)], and we add the minimal-conformal part in a follow-up paper to complete the full self-mass-squared at one-loop order. The computation is performed using dimensional regularization, and the results are fully renormalized by absorbing divergences with counterterms. The finite results can give rise to quantum corrections to the CC scalar mode functions and therefore to their power spectra. [ABSTRACT FROM AUTHOR]

Chaotic inflation based on a simple monomial scalar potential, V(ϕ)αϕp, is an attractive large-field model of inflation capable of generating a sizable tensor-to-scalar ratio r. Therefore, assuming that future cosmic microwave background observations will confirm the large r value reported by BICEP2, it is important to determine what kind of dynamical mechanism could possibly endow the inflaton field with such a simple effective potential. In this paper, we answer this question in the context of field theory, i.e. in the framework of dynamical chaotic inflation, where strongly interacting supersymmetric gauge dynamics around the scale of grand unification dynamically generate a fractional power-law potential via the quantum effect of dimensional transmutation. In constructing explicit models, we significantly extend our previous work, as we now consider a large variety of possible underlying gauge dynamics and relax our conditions on the field content of the model. This allows us to realize almost arbitrary rational values for the power p in the inflaton potential. The present paper may hence be regarded as a first step toward a more complete theory of dynamical chaotic inflation. [ABSTRACT FROM AUTHOR]

In our previous paper [K. Feng, T. Qiu, and Y.-S. Piao, Phys. Lett. B 729, 99 (2014)], we have shown a curvaton model where the curvaton has a nonminimal derivative coupling to gravity. Such a coupling could cause scale invariance of the perturbations for a wide range of constant values of the equation of state of the cosmic background at the early time. In this paper, we continue our study by fully analyzing its perturbations up to the third order. Apart from the usual 2-point correlation function that have already been calculated in Feng, Qiu, and Piao [Phys. Lett. B 729, 99 (2014)], we also take into account the 3-point correlation functions, including the pure scalar part, the pure tensor part, and the cross-correlations between scalar and tensor perturbation modes. We find that for the pure scalar part, the 3-point correlation functions can generate non-Gaussianities that fit the PLANCK data very well. For the pure tensor and mixed parts, the shape functions have peaks at squeezed and equilateral limits, respectively, responsible for sizable fsqzNL and fsqzNL, which could be tested by the future observational data. [ABSTRACT FROM AUTHOR]

Recently, we studied perturbations in the Lemaitre-Tolman-Bondi cosmological model by applying the second-order perturbation theory in the dust Friedmann-LemaTtre-Robertson-Walker universe model. Before this work, the same subject was studied in some papers by analyzing linear perturbations in the Lemaitre-Tolman-Bondi cosmological model under the assumption proposed by Clarkson, Clifton, and February, in which two perturbation variables are negligible. However, it is a nontrivial issue in what situation the Clarkson-Clifton-February assumption is valid. In this paper, we investigate differences between these two approaches. It is shown that, in general, these two approaches are not compatible with each other. That is, in our perturbative procedure, the Clarkson-Clifton-February assumption is not valid at the order of our interest. [ABSTRACT FROM AUTHOR]

We suggest a criterion to minimize the amount of fine-tuning in a composite Higgs model. The paradigm of this type of model is the top-condensate model of Bardeen-Hill-Lindner. Although "minimally fine-tuned," this model fails to account correctly for the masses of the top quark and the 125 GeV Higgs boson. We propose a generalization of the Bardeen-Hill-Lindner model that employs finely tuned extended technicolor plus technicolor (TC) interactions. The additional freedom of this model may accommodate both mt(173) and MH(125). This paper studies the large-NTC and -NC limit of this model in which technicolor is weak and does not contribute to electroweak symmetry breaking. Refinements including walking-TC dynamics and a renormalization-group analysis of mt and MH will appear in a subsequent paper. A likely generic signal of this model is enhanced production of longitudinally polarized weak bosons, alone and in association with H(125). [ABSTRACT FROM AUTHOR]

In the companion paper it is shown that there are six observables in gg → tt (bbc)(bℓν) that can be used to reveal the presence of new physics (NP) in t bbc. In the present paper we examine the prospects for detecting and identifying such NP at the LHC, in both the short term and long term. To this end, we develop an algorithm for extracting the NP parameters from measurements of the observables. In the short term, depending on what measurements have been made, there are several different ways of detecting the presence of NP. It may even be possible to approximately determine the values of certain NP parameters. In the long term, it is expected that all six observables will be measured. The values of the NP parameters can then be determined reasonably precisely from a fit to these measurements, which will provide good information about the type of NP present in t → bbc. [ABSTRACT FROM AUTHOR]

The emergence of the seeds of cosmic structure, from a perfect isotropic and homogeneous Universe, has not been clearly explained by the standard version of inflationary models as the dynamics involved preserve the homogeneity and isotropy at all times. A proposal that attempts to deal with this problem, by introducing "the self-induced collapse hypothesis," has been introduced by D. Sudarsky and collaborators in previous papers. In all these works, the collapse of the wave function of the inflaton mode is restricted to occur during the inflationary period. In this paper, we analyze the possibility that the collapse happens during the radiation era. A viable model can be constructed under the condition that the inflaton field variable must be affected by the collapse while the momentum variable can or cannot be affected. Another condition to be fulfilled is that the time of collapse must be independent of k. However, when comparing with recent observational data, the predictions of the model cannot be distinguished from the ones provided by the standard inflationary scenario. The main reason for this arises from the requirement that primordial power spectrum obtained for the radiation era matches the amplitude of scalar fluctuations consistent with the latest cosmic microwave background observations. This latter constraint results in a limit on the possible times of collapse and ensures that the contribution of the inflaton field to the energy-momentum tensor is negligible compared to the contribution of the radiation fields. [ABSTRACT FROM AUTHOR]

Compact binary coalescences are a promising source of gravitational waves for second-generation interferometric gravitational-wave detectors. Although matched filtering is the optimal search method for well-modeled systems, alternative detection strategies can be used to guard against theoretical errors (e.g., involving new physics and/or assumptions about spin or eccentricity) while providing a measure of redundancy. In a previous paper, we showed how "seedless clustering" can be used to detect long-lived gravitational-wave transients in both targeted and all-sky searches. In this paper, we apply seedless clustering to the problem of low-mass (Mtotal ≤ 10M0) compact binary coalescences for both spinning and eccentric systems. We show that seedless clustering provides a robust and computationally efficient method for detecting low-mass compact binaries. [ABSTRACT FROM AUTHOR]

In this paper, we study residual symmetries in the lepton sector. Our first concern is the symmetry of the charged lepton mass matrix in the basis where the Majorana neutrino mass matrix is diagonal, which is strongly constrained by the requirement that the symmetry group generated by residual symmetries is finite. In a recent work, R. M. Fonseca and W. Grimus found that there exists a set of constraint equations that can be completely solved, which is essential in their approach to the classification of lepton mixing matrices that are fully determined by residual symmetries. In this paper, a method to handle trigonometric Diophantine equations is introduced. We will show that the constraint equations found by Fonseca and Grimus can also be solved by this method. Detailed derivation and discussion will be presented in a selfcontained way. In addition, we will also show that, in the case where residual symmetries satisfy a reality condition, this method can be used to solve the equation constraining parameters in the symmetry assignment that controls the group structure generated by residual symmetries and is directly related to mixing matrix elements. [ABSTRACT FROM AUTHOR]

If two particles collide near a black hole, the energy in their center of mass can, under certain conditions, grow unbounded. This is Bafiados-Silk-West effect. We show that this effect retains its validity even if some force acts on a particle, provided some reasonable and weak restrictions are imposed on this force. In the present paper we discuss the case of nonextremal horizons. The result under discussion is similar to that for extremal horizons considered in our previous paper. The problem can be viewed both in its own right and as a simple setup in which this force models in the first approximation the complicated gravitational self-force. [ABSTRACT FROM AUTHOR]

It is well known that charged black Dp branes of type II string theory share a universal phase structure of van der Waals-Maxwell liquid-gas type except D5 and D6 branes. Interestingly, the phase structure of D5 and D6 branes can be changed to the universal form with the inclusion of particular delocalized charged lower-dimensional branes. For D5 branes, one needs to introduce delocalized D1 branes, and for D6 branes, one needs to introduce delocalized DO branes to obtain the universal structure. In a previous paper [J. High Energy Phys. 04 (2013) 100], Lu with Wei study the phase structure of black D6 branes with the introduction of delocalized DO branes in a special case when their charges are equal and the dilaton charge vanishes. In this paper, we look at the phase structure of the black D6/D0 system with the generic values of the parameters, which makes the analysis more involved but the structure more rich. We also provide reasons why the respective modifications of the phase structures to the universal form for the black D5 and D6 branes occur when specific delocalized lower-dimensional branes are introduced. [ABSTRACT FROM AUTHOR]

We propose a new antenna configuration of a torsion-bar antenna (TOBA) and study its performance. A TOBA is a novel type of an antenna for low-frequency gravitational waves (GWs) which consists of two bar-shaped orthogonal test masses. Previously only the rotation of the bars on the horizontal plane had been considered as an output signal. In this paper, we introduce a new antenna configuration for a TOBA to incorporate two additional outputs by measuring the rotation of the bars on the vertical planes. Such a triple-output TOBA can be regarded as a network of three coincident but misaligned interferometric detectors. The target sensitivity we consider in this paper is about 3 × 10-20 Hz-1/2 at 1 Hz. Since the triple-output TOBA is sensitive to all directions of GWs, event detection rates are improved by a factor of 1.7. It also increases the parameter resolution drastically for short-duration observations because the triple-output TOBA has three independent output signals and can discriminate two polarization modes of a short-duration GW signal even with single antenna. For instance, in the case of a 104-104 IMBH merger at 100 Mpc, the source location is typically measurable with an accuracy of ±0.01-0.1 steradians which is roughly two order of magnitude better than the conventional single-output TOBA. [ABSTRACT FROM AUTHOR]

In this paper we discuss search strategies at the LHC for light electroweak gauginos which are mostly wino-like, Higgsino-like or an admixture. These states are typically degenerate with decay products that are less energetic and hence difficult to detect. In addition, their production cross sections at a hadron collider are suppressed compared to colored states such as the gluinos. In order to detect these states one needs to trigger on initial-or final-state radiation. Many previous analyses have focussed on mono-jet and monophoton triggers. In this paper we argue and show that these triggers are unlikely to succeed, due to the large background from QCD backgrounds for the mono-jet searches and the fact that the p T distribution of the mono-photons are rapidly decreasing functions of pT. We show this with both an analytic calculation of photons in the initial-state radiation and also a detailed numerical analysis. We then argue that mono-Z triggers, from Z decaying into charged leptons may well provide the best search strategy, in particular for Higgsino-like and mixed cases. [ABSTRACT FROM AUTHOR]

In performing cosmological N-body simulations, it is widely appreciated that the growth of structure on the largest scales within a simulation box will be inhibited by the finite size of the simulation volume. Following ideas set forth by Seto Astrophys. J. 523, 24 (1999), this paper shows that standard (also known as one-loop) cosmological perturbation theory (SPT) [E. T. Vishniac, Mon. Not. R. Astron. Soc. 203, 345 (1983)] can be used to predict, in an approximate way, the deleterious effect of the box scale on the power spectrum of density fluctuations in simulation volumes. Alternatively, this approach can be used to quickly estimate post facto the effect of the box scale on power spectrum results from existing simulations. In this way SPT can help determine whether larger box sizes or other more-sophisticated methods are needed to achieve a particular level of precision for a given application (e.g. simulations to measure the nonlinear evolution of baryon acoustic oscillations). I focus on SPT in this paper and show that its predictions differ only by about a factor of 2 or less from the measured suppression inferred from both power law and ACDM

crucial that strong foreground contaminants be robustly suppressed. These foregrounds come from a variety of sources (such as Galactic synchrotron emission and extragalactic point sources), but almost all share the property of being spectrally smooth and, when viewed through the chromatic response of an interferometer, occupy a signature "wedge" region in cylindrical kIkII Fourier space. The complement of the foreground wedge is termed the "EoR window" and is expected to be mostly foreground-free, allowing clean measurements of the power spectrum. This paper is a sequel to a previous paper that established a rigorous mathematical framework for describing the foreground wedge and the EoR window. Here, we use our framework to explore statistical methods by which the EoR window can be enlarged, thereby increasing the sensitivity of a power spectrum measurement. We adapt the Feldman-Kaiser-Peacock approximation (commonly used in galaxy surveys) for 21 cm cosmology and also compare the optimal quadratic estimator to simpler estimators that ignore covariances between different Fourier modes. The optimal quadratic estimator is found to suppress foregrounds by an extra factor of ~105 in power at the peripheries of the EoR window, boosting the detection of the cosmological signal from 12σ to 50σ at the midpoint of reionization in our fiducial models. If numerical issues can be finessed, decorrelation techniques allow the EoR window to be further enlarged, enabling measurements to be made deep within the foreground wedge. These techniques do not assume that foreground is Gaussian distributed, and we additionally prove that a final round of foreground subtraction can be performed after decorrelation in a way that is guaranteed to have no cosmological signal loss. [ABSTRACT FROM AUTHOR]

We study phenomenological aspects of the bino-wino coannihilation scenario in high-scale supersymmetry (SUSY)-breaking models. High-scale SUSY-breaking scenarios aie considered to be a promising possibility after the discovery of the Higgs boson with a mass around 126 GeV. In this paper, we discuss the bino lightest supersymmetric particle (LSP), accompanied by the (at most) around 30 GeV heavier wino. With suitable mass splitting between the bino and the wino, the bino LSP has the correct relic abundance of dark matter. For a smaller mass splitting, the late-time decay of the gravitino can provide the correct abundance of bino dark matter. It is extremely challenging to find signals from the bino dark matter in direct and indirect detections. By utilizing multijets plus missing transverse momentum events at the LHC, we can constrain the gluino mass and thus probe the bino-wino coannihilation scenario indirectly. The collider experiment, however, cannot search the bino dark matter directly. In this paper, we suggest the direct probe of the bino dark matter. We show that the bino dark matter leaves imprints on the small-scale matter power spectrum when the bino dark matter is produced by the decay of the gravitino. The nonthermal bino dark matter behaves as mixed (cold + warm) dark matter. [ABSTRACT FROM AUTHOR]

This paper reports on an unmodeled, all-sky search for gravitational waves from merging intermediate mass black hole binaries (IMBHB). The search was performed on data from the second joint science run of the LIGO and Virgo detectors (July 2009-October 2010) and was sensitive to IMBHBs with a range up to ~200 Mpc, averaged over the possible sky positions and inclinations of the binaries with respect to the line of sight. No significant candidate was found. Upper limits on the coalescence-rate density of nonspinning IMBHBs with total masses between 100 and 450 MO and mass ratios between 0.25 and 1 were placed by combining this analysis with an analogous search performed on data from the first LIGO-Virgo joint science run (November 2005-October 2007). The most stringent limit was set for systems consisting of two 88 MO black holes and is equal to 0.12 Mpc-3 Myr-1 at the 90% confidence level. This paper also presents the first estimate, for the case of an unmodeled analysis, of the impact on the search range of IMBHB spin configurations: the visible volume for IMBHBs with nonspinning components is roughly doubled for a population of IMBHBs with spins aligned with the binary's orbital angular momentum and uniformly distributed in the dimensionless spin parameter up to 0.8, whereas an analogous population with antialigned spins decreases the visible volume by ~20%. [ABSTRACT FROM AUTHOR]

This paper deals with a special kind of problems that appear in solutions of Einstein's field equations for extended bodies: many structure-dependent terms appear in intermediate calculations that cancel exactly in virtue of the local equations of motion or can be eliminated by appropriate gauge transformations. For a single body at rest, these problems are well understood for both the post-Newtonian and the post-Minkowskian cases. However, the situation is still unclear for approximations of higher orders. This paper discusses this problem for a "body" of spherical symmetry to post-linear order. We explicitly demonstrate how the usual Schwarzschild field can be derived direcdy from the field equations in the post-linear approximation in the harmonic gauge and for an arbitrary spherically symmetric matter distribution. Both external and internal solutions are considered. The case of static incompressible fluid is then compared to the well-known results from the literature. The results of this paper can be applied to generalize the well-known post-Newtonian and post-Minkowskian multipole expansions of the metric in the post-linear approximation. [ABSTRACT FROM AUTHOR]

The cosmological birefringence caused by the coupling between the cosmic scalar field and the cosmic microwave background (CMB) photons through the Chern-Simons term can rotate the polarization planes of the photons and mix the CMB E-mode and B-mode polarizations. The rotation angle induced by the dynamical scalar field can be separated into the isotropic background part and the anisotropic fluctuations. The effect of the background part has been studied in our previous work (Zhao and Li, arXiv:1402.4324). In this paper, we focus on the influence of the anisotropies of the rotation angle. We first assume that the cosmic scalar field is massless, consistent with other works, and we find that the rotation spectrum can be quite large, which may be detected by the potential CMB observations. However, if the scalar field is identified as the quintessence field, by detailed discussion of both the entropy and adiabatic perturbation modes for the first time, we find that the anisotropies of the rotation angle are always too small to be detectable. In addition, as the main goal of this paper, we investigate the effect of a rotated polarization power spectrum on the detection of relic gravitational waves. We find that the rotated B-mode polarization could be fairly large and comparable with those generated by the gravitational waves. This forms a new contamination for the detection of relic gravitational waves in the CMB. In particular, we also propose the method to reconstruct and subtract the rotated B-mode polarization, by which the residuals become negligible for the gravitational-wave detection. [ABSTRACT FROM AUTHOR]

If low-energy supersymmetry (SUSY) exists, LHC data favors a high mass scale for scalar superpartners (above a TeV), while sfermions and the dark matter can be parametrically lighter--leading to a so-called split spectrum. When combining this fact with the motivation from fundamental theory for shift-symmetric scalars (moduli) prior to SUSY breaking, this leads to a nonthermal history for the early universe. Such a history implies different expectations for the microscopic properties of dark matter, as well as the possibility of dark radiation and a cosmic axion background. In this paper we examine how correlated and mixed isocurvature perturbations are generated in such models, as well as the connection to dark radiation. WMAP constraints on multiple correlated isocurvature modes allow up to half of the primordial perturbations to be isocurvature, contrary to the case of a single isocurvature mode where perturbations must be dominantly adiabatic. However, such bounds are strongly prior dependent, and have not been investigated with the latest Planck data. In this paper we use the example of a SUSY nonthermal history to establish theoretical priors on cosmological parameters. Of particular interest, we find that priors on dark radiation are degenerate with those on the total amount of isocurvature--they are inversely correlated. Dark radiation is tightly constrained in the early universe and has been used recently to place stringent constraints on string-based approaches to beyond the standard model. Our results suggest such constraints can require more input from theory. Specifically, we find that in many cases constraints on dark radiation are avoidable because the density can be reduced at the expense of predicting an amount of multicomponent isocurvature. The latter are poorly constrained by existing probes, and lead to the interesting possibility that such models could have new predictions for the next generation of observations. Our results are not only important for establishing the postinflationary universe in the presence of SUSY, but also suggest that data from cosmological probes--such as Planck--can help guide model building in models of the minimal SUSY standard model, split SUSY, and beyond. Our model also demonstrates the utility of UV models in constructing cosmological priors. [ABSTRACT FROM AUTHOR]

This paper investigates the Faraday effect as a different source of ß-mode polarization. The E-mode polarization is Faraday rotated provided a stochastic large-scale magnetic field is present prior to photon decoupling. In the first part of the paper we discuss the case where the tensor modes of the geometry are absent and we argue that the ß mode recently detected by the BICEP2 Collaboration cannot be explained by a large-scale magnetic field rotating, through the Faraday effect, the well-established £-mode polarization. In this case, the observed temperature autocorrelations would be excessively distorted by the magnetic field. In the second part of the paper the formation of Faraday rotation is treated as a stationary, random and Markovian process with the aim of generalizing a set of scaling laws originally derived in the absence of the tensor modes of the geometry. We show that the scalar, vector and tensor modes of the brightness perturbations can all be Faraday rotated even if the vector and tensor parts of the effect have been neglected, so far, by focussing the attention on the scalar aspects of the problem. The mixing between the power spectra of the Zs-mode and B-mode polarizations involves a unitary transformation depending nonlinearly on the Faraday rotation rate. The present approach is suitable for a general scrutiny of the polarization observables and of their frequency dependence. [ABSTRACT FROM AUTHOR]

In the current paper the properties of a birefringent Lorentz-violating extension of quantum electrodynamics is considered. The theory results from coupling modified Maxwell theory, which is a CTT-even Lorentz-violating extension of the photon sector, to a Dirac theory of standard spin-1/2 particles. It is then restricted to a special birefringent case with one nonzero Lorentz-violating coefficient. The modified dispersion laws of electromagnetic waves are obtained plus their phase and group velocities are considered. After deriving the photon propagator and the polarization vectors for a special momentum configuration we prove both unitarity at tree level and microcausality for the quantum field theory based on this Lorentz-violating modification. These analytical proofs are done for a spatial momentum with two vanishing components and the proof of unitarity is supported by numerical investigations in case all components are nonvanishing. The upshot is that the theory is well behaved within the framework of our assumptions where there is a possible issue for negative Lorentz-violating coefficients. The paper shall provide a basis for the future analysis of alternative birefringent quantum field theories. [ABSTRACT FROM AUTHOR]