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We present a constructive derivation of all four-point tree-level holographic correlators for eleven dimensional supergravity on ${\mathrm{AdS}}_{7}\ifmmode\times\else\texttimes\fi{}{S}^{4}$. These correlators correspond to four-point functions of arbitrary one-half BPS operators in the six-dimensional (2,0) theory at large central charge. The crucial observation is that the polar part of the correlators in Mellin space is fully captured by a drastically simpler maximally $R$-symmetry violating amplitude, while the contact part is fully fixed by superconformal Ward identities and the flat space limit.

The Bianchi identities for bosonic fluxes in supergravity can receive higher derivative quantum and string corrections, the most well known being that of heterotic theory $\mathrm{d}H=\frac{1}{4}{\ensuremath{\alpha}}^{\ensuremath{'}}(\mathrm{t}\mathrm{r}\text{ }{F}^{2}\ensuremath{-}\mathrm{t}\mathrm{r}\text{ }{R}^{2})$. Less studied are the modifications at order ${R}^{4}$ that may arise, for example, in the Bianchi identity for the seven-form flux of M theory compactifications. We argue that such corrections appear to be incompatible with the exceptional generalized geometry description of the lower order supergravity, and seem to imply a gauge algebra for the bosonic potentials that cannot be written in terms of an (exceptional) Courant bracket. However, we show that this algebra retains the form of an ${L}_{\ensuremath{\infty}}$ gauge field theory, which terminates at a level ten multibracket for the case involving just the seven-form flux.

We present a first principles derivation of the anomaly polynomials of 4d N=2 class S theories of type AN−1 with arbitrary regular punctures, using anomaly inflow in the corresponding M-theory setup with N M5-branes wrapping a punctured Riemann surface. The labeling of punctures in our approach follows entirely from the analysis of the 11d geometry and G4 flux. We highlight the applications of the inflow method to the AdS/CFT correspondence.

We study supersymmetric solutions within seven-dimensional $N=2$ gauged supergravity coupled to three vector multiplets in seven dimensions. The gauged supergravity contains six vector fields that gauge the $SO(4)\sim SO(3)\times SO(3)$ symmetry and admits two $N=2$ supersymmetric $AdS_7$ vacua with $SO(4)$ and $SO(3)_{\textrm{diag}}\subset SO(3)\times SO(3)$ symmetries. We consider solutions interpolating between two asymptotically locally $AdS_7$ geometries in the presence of a three-form field. For a particular value of the two $SO(3)$ gauge coupling constants, the $SO(3)_{\textrm{diag}}$ supersymmetric $AdS_7$ vacuum does not exist, but the solutions can be uplifted to eleven dimensions by a known reduction ansatz. We also study solutions of this type and their embedding in M-theory. We further extend these solutions to include the $SO(3)_{\textrm{diag}}$ gauge fields and argue that, in general, this generalization does not lead to supersymmetric solutions., 22 pages, no figure, typos corrected, minor changes

Axions arise in many theoretical extensions of the Standard Model of particle physics, in particular the "string axiverse". If the axion masses, $m_a$, and (effective) decay constants, $f_a$, lie in specific ranges, then axions contribute to the cosmological dark matter and dark energy densities. We compute the background cosmological (quasi-)observables for models with a large number of axion fields, $n_{\rm ax}\sim \mathcal{O}(10-100)$, with the masses and decay constants drawn from statistical distributions. This reduces the number of parameters from $2n_{\rm ax}$ to a small number of "hyperparameters". We consider a number of distributions, from those motivated purely by statistical considerations, to those where the structure is specified according to a class of M-theory models. Using Bayesian methods we are able to constrain the hyperparameters of the distributions. In some cases the hyperparameters can be related to string theory, e.g. constraining the number ratio of axions to moduli, or the typical decay constant scale needed to provide the correct relic densities. Our methodology incorporates the use of both random matrix theory and Bayesian networks.

We study various supersymmetric renormalization group (RG) flows of $N=3$ Chern-Simons-Matter theory in three dimensions by using four-dimensional $N=3$ gauged supergravity coupled to eight vector multiplets with $SO(3)\ifmmode\times\else\texttimes\fi{}SU(3)$ gauge group. The ${\mathrm{AdS}}_{4}$ critical point preserving the full $SO(3)\ifmmode\times\else\texttimes\fi{}SU(3)$ provides a gravity dual of $N=3$ superconformal field theory with flavor symmetry $SU(3)$. We study the scalar potential and identify a new supersymmetric ${\mathrm{AdS}}_{4}$ critical point preserving the full $N=3$ supersymmetry and unbroken $SO(3)\ifmmode\times\else\texttimes\fi{}U(1)$ symmetry. An analytic RG flow solution interpolating between $SO(3)\ifmmode\times\else\texttimes\fi{}SU(3)$ and $SO(3)\ifmmode\times\else\texttimes\fi{}U(1)$ critical points is explicitly given. We then investigate possible RG flows from these ${\mathrm{AdS}}_{4}$ critical points to nonconformal field theories in the IR. All of the singularities appearing in the IR turn out to be physically acceptable. Furthermore, we look for supersymmetric solutions of the form ${\mathrm{AdS}}_{2}\ifmmode\times\else\texttimes\fi{}{\mathrm{\ensuremath{\Sigma}}}_{2}$ with ${\mathrm{\ensuremath{\Sigma}}}_{2}$ being a two-sphere or a two-dimensional hyperbolic space and find a number of ${\mathrm{AdS}}_{2}$ geometries preserving four supercharges with $SO(2)\ifmmode\times\else\texttimes\fi{}SO(2)\ifmmode\times\else\texttimes\fi{}SO(2)$ and $SO(2)\ifmmode\times\else\texttimes\fi{}SO(2)$ symmetries.

Conifold geometries have recieved a lot of attention in string theory and string-inspired cosmology recently, in particular the Klebanov-Strassler background that is known as the "warped throat". It is our intention in this article to give a pedagogical explanation for the singularity resolution in this geometry and emphasise its connection to geometric transitions. The first part focuses on the gauge theory dual to the Klebanov-Strassler background, which we also explain from a T-dual intersecting branes scenario. We then make the connection to the Gopakumar-Vafa conjecture for open/closed string duality and summarise a series of papers verifying this model on the supergravity level. An appendix provides extensive background material about conifold geometries. We pay special attention to their complex structures and re-evaluate the supersymmetry conditions on the background flux in constructions with fractional D3-branes on the singular (Klebanov-Tseytlin) and resolved (Pando Zayas-Tseytlin) conifolds. We agree with earlier results that only the singular solution allows a supersymmetric flux, but point out the importance of using the correct complex structure to reach this conclusion., 37 pages, v3: accepted for publication in Reviews of Modern Physics

We consider grand unified theories based on $SO(10)$ which originate from $\text{string}/M$ theory on ${G}_{2}$ manifolds or Calabi-Yau spaces with discrete symmetries. In this framework we are naturally led to a novel solution of the doublet-triplet splitting problem previously considered by Dvali which involves an extra vectorlike Standard Model family and light but weakly coupled color triplets. These additional states are predicted to be accessible at the LHC and also induce R-parity violation. Gauge coupling unification occurs with a larger GUT coupling.

A coset model based on the hyperbolic Kac–Moody algebra E10 has been conjectured to underly eleven-dimensional supergravity and M theory. In this note we study the canonical structure of the bosonic model for finite- and infinite-dimensional groups. In the case of finite-dimensional groups like GL(n) we exhibit a convenient set of variables with Borel-type canonical brackets. The generalisation to the Kac–Moody case requires a proper treatment of the imaginary roots that remains elusive. As a second result, we show that the supersymmetry constraint of D = 11 supergravity can be rewritten in a suggestive way using E10 algebra data. Combined with the canonical structure, this rewriting explains the previously observed association of the canonical constraints with null roots of E10. We also exhibit a basic incompatibility between local supersymmetry and the K(E10) ‘R symmetry’, that can be traced back to the presence of imaginary roots and to the unfaithfulness of the spinor representations occurring in the present formulation of the E10 worldline model, and that may require a novel type of bosonisation/fermionisation for its resolution. This appears to be a key challenge for future progress with E10.

E-strings arise from M2 branes suspended between an M5 brane and an M9 plane. In this paper we obtain explicit expressions for the elliptic genus of two E-strings using a series of string dualities. Moreover we show how this can be used to recover the elliptic genus of two ${E}_{8}\ifmmode\times\else\texttimes\fi{}{E}_{8}$ heterotic strings using the Ho\ifmmode \check{r}\else \v{r}\fi{}ava--Witten realization of heterotic strings in M-theory. This involves highly nontrivial identities among Jacobi forms and is remarkable in light of the fact that E-strings are ``sticky'' and form bound states whereas heterotic strings do not form bound states.

We present a unifying theme relating BPS partition functions and superconformal indices. In the case with complex SUSY central charges (as in N=2 in d=4 and N=(2,2) in d=2) the known results can be reinterpreted as the statement that the BPS partition functions can be used to compute a specialization of the superconformal indices. We argue that in the case with real central charge in the supersymmetry algebra, as in N=1 in d=5 (or the N=2 in d=3), the BPS degeneracy captures the full superconformal index. Furthermore, we argue that refined topological strings, which captures 5d BPS degeneracies of M-theory on CY 3-folds, can be used to compute 5d supersymmetric index including in the sectors with 3d defects for a large class of 5d superconformal theories. Moreover, we provide evidence that distinct Calabi-Yau singularities which are expected to lead to the same SCFT yield the same index., Comment: 58 pages

We study ${\mathrm{AdS}}_{7}/{\mathrm{CFT}}_{6}$ correspondence between M theory on ${\mathrm{AdS}}_{7}\ifmmode\times\else\texttimes\fi{}{S}^{4}$ and the 6D $\mathcal{N}=(2,0)$ superconformal field theory. In particular, we focus on Wilson surfaces. We use the conjecture that the (2,0) theory compactified on ${S}^{1}$ is equivalent to the 5D maximal super-Yang-Mills (MSYM), and Wilson surfaces wrapping this ${S}^{1}$ correspond to Wilson loops in 5D MSYM. The Wilson loops in 5D MSYM obtained by the localization technique result in the Chern-Simons matrix model. We calculate the expectation values of Wilson surfaces in large-rank symmetric representations and antisymmetric representations by using this result. On the gravity side, the expectation values for probe M5-branes wrapping submanifolds of the background are computed. Consequently, we find new, nontrivial evidence for the ${\mathrm{AdS}}_{7}/{\mathrm{CFT}}_{6}$ correspondence that the results on the gravity side perfectly agree with those on the CFT side.

In this paper, we first compute the Killing spinors of ${\mathrm{AdS}}_{4}\ifmmode\times\else\texttimes\fi{}{Q}^{1,1,1}$ and its certain orbifolds. Based on this, two classes of $M2$-brane solutions are found. The first class of solutions includes $M2$-branes dual to Wilson loops in the fundamental representation as a special case. The second class includes the candidates of the holographic description of vortex loops in the dual field theories.

We present the details of the recently constructed ${\mathrm{E}}_{6(6)}$-covariant extension of 11-dimensional supergravity. This theory requires a $5+27$-dimensional spacetime in which the ``internal'' coordinates transform in the $\overline{\mathbf{27}}$ of ${\mathrm{E}}_{6(6)}$. All fields are ${\mathrm{E}}_{6(6)}$ tensors and transform under (gauged) internal generalized diffeomorphisms. The ``Kaluza-Klein'' vector field acts as a gauge field for the ${\mathrm{E}}_{6(6)}$-covariant ``E-bracket'' rather than a Lie bracket, requiring the presence of 2-forms akin to the tensor hierarchy of gauged supergravity. We construct the complete and unique action that is gauge invariant under generalized diffeomorphisms in the internal and external coordinates. The theory is subject to covariant section constraints on the derivatives, implying that only a subset of the extra 27 coordinates is physical. We give two solutions of the section constraints: the first preserves GL(6) and embeds the action of the complete (i.e. untruncated) 11-dimensional supergravity; the second preserves $\text{GL}(5)\ifmmode\times\else\texttimes\fi{}\text{SL}(2)$ and embeds complete type IIB supergravity. As a byproduct, we thus obtain an off-shell action for type IIB supergravity.

As argued by Witten on the basis of M-theory, QCD strings can end on domain walls. We present an explanation of this effect in the framework of effective field theories for the Polyakov loop and the gluino condensate in N=1 supersymmetric QCD. The domain walls separating confined phases with different values of the gluino condensate are completely wet by a layer of deconfined phase at the high-temperature phase transition. As a consequence, even at low temperatures, the Polyakov loop has a non-vanishing expectation value on the domain wall. Thus, close to the wall, the free energy of a static quark is finite and the string emanating from it can end on the wall., Comment: 8 pages, 2 figures

We compute graviton scattering amplitudes in M-theory using Feynman rules for a scalar particle coupled to gravity in eleven dimensions. The processes that we consider describe the single graviton exchange and the double graviton exchange, that in M(atrix) theory correspond to the $v^4/r^7$- and $v^6/r^{14}$-term respectively. We further show that the $ v^6/r^{14}$-term appearing in M(atrix) theory at two-loops can be obtained from the covariant eleven-dimensional four-graviton amplitude. Finally, we calculate the $v^8/r^{18}$-term appearing at two-loops in M(atrix) theory. It has been previously conjectured that this term is related to a four graviton scattering amplitude involving the $R^4$-vertex of M-theory., 16 pages, tex, no figures

We investigate Seiberg{close_quote}s N=1 field theory duality for four-dimensional supersymmetric QCD with the M-theory 5-brane. We find that the M-theory configuration for the magnetic dual theory arises via a smooth deformation of the M-theory configuration for the electric theory. The creation of Dirichlet 4-branes as Neveu-Schwarz 5-branes are passed through each other in type IIA string theory is given an elegant derivation from M theory. {copyright} {ital 1998} {ital The American Physical Society}

The potential between two D4-branes at angles with partially unbroken supersymmetry is computed, and is used to discuss the creation of a fundamental string when two such D4-branes cross each other in M(atrix) theory. The effective Lagrangian is shown to be anomalous at 1-loop approximation, but it can be modified by bare Chern-Simons terms to preserve the invariance under the large gauge transformation. The resulting effective potential agrees with that obtained from the string calculations. The result shows that a fundamental string is created in order to cancel the repulsive force between two D4-branes at proper angles.

Some gauge theories with Coulomb branches exhibit singularities in perturbation theory, which are usually resolved by nonperturbative physics. In string theory this corresponds to the resolution of timelike singularities near the core of orientifold planes by effects from F or M theory. We propose a new mechanism for resolving Coulomb branch singularities in three dimensional gauge theories, based on Chern-Simons interactions. This is illustrated in a supersymmetric SU(2) Yang-Mills-Chern-Simons theory. We calculate the one loop corrections to the Coulomb branch of this theory and find a result that interpolates smoothly between the high energy metric (that would exhibit the singularity) and a regular singularity-free low energy result. We suggest possible applications to singularity resolution in string theory and speculate a relationship to a similar phenomenon for the orientifold six-plane in massive IIA supergravity., 24 pages, 1 figure. Revised version, references added

We obtain the Matrix model equations in the background of the maximally supersymmetric $pp$-wave solution of the 11D supergravity and discuss its relation with the Berenstein-Maldacena-Nastase model.

Made available in DSpace on 2022-04-29T02:55:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-03-07 In the presence of a background supergravity flux, N M2-branes will expand via the Myers effect into M5-branes wrapped on a fuzzy 3-sphere. In previous work the fluctuations of the M2-branes were shown to be described by the five-dimensional Yang-Mills gauge theory associated to D4-branes. We show that the Aharony-Bergman-Jafferis-Maldacena prescription for 11-dimensional momentum in terms of magnetic flux lifts to an instanton flux of the effective five-dimensional Yang-Mills theory on the sphere, giving an M-theory interpretation for these instantons. © 2012 American Physical Society. Theory Division CERN, 1211 Geneva 23 IFT UNESP-Universidade Estadual Paulista, São Paulo 01140-070, SP NHETC Department of Physics and Astronomy Rutgers University, Piscataway, NJ 08854-8019 IFT UNESP-Universidade Estadual Paulista, São Paulo 01140-070, SP

We investigate a squashing deformation of 3d N=2 supersymmetric theories on three-sphere, which have four supercharges. The deformation preserves SU(2)_L x U(1)_r isometry and all four supersymmetries. We compute the partition function and find non-trivial dependence on the squashing parameter. We also consider the large N limit of a certain class of quiver gauge theories which have free energy of order N^{3/2}, and show that the free energy on the squashed sphere differs from that on round sphere by a certain factor depending only on the squashing parameter., Comment: 39 pages, 2 figures, v2: minor corrections, references added; v3: minor corrections

We carry out the first holographic calculation of a fermionic response function for a strongly coupled $d=3$ system with an explicit D=10 or D=11 supergravity dual. By considering the supersymmetry current, we obtain a universal result applicable to all d=3 N=2 SCFTs with such duals. Surprisingly, the spectral function does not exhibit a Fermi surface, despite the fact that the system is at finite charge density. We show that it has a phonino pole and at low frequencies there is a depletion of spectral weight with a power-law scaling which is governed by a locally quantum critical point., Comment: 5 pages. Content the same, but significant change of presentation. Version to be published in Phys. Rev. Lett

Using hyperbolic temporal and spatial cutoffs to define four-dimensional asymptotically flat spacetimes, we show that supertranslation ambiguities in the asymptotic fields can all be removed even in the presence of gravitational magnetic charges. We then show that configurations with different electric and magnetic four-momenta can be consistently considered in the Mann-Marolf variational principle. This generalizes the previous result where variations over asymptotically flat configurations with fixed magnetic four-momenta were considered. We also express the Kerr Taub-NUT metric to the leading and next-to-leading order in the Beig-Schmidt form, and compare the asymptotic form with the tensor harmonics on three-dimensional de Sitter space.

We propose that $N$ M5-branes, put on ${\mathbb{R}}^{4}/{\mathbb{Z}}_{m}$ with deformation parameters ${ϵ}_{1,2}$, realize two-dimensional theory with $\stackrel{^}{\mathrm{SU}}(m{)}_{N}$ symmetry and $m$th para-${W}_{N}$ symmetry. This includes the standard ${W}_{N}$ symmetry for $m=1$ and super-Viraroro symmetry for $m=N=2$. We provide a small check of this proposal by calculating the central charge of the 2D theory from the anomaly polynomial of the 6D theory.

We study the $d=11$ gravity dual ${\mathrm{AdS}}_{4}\ifmmode\times\else\texttimes\fi{}N(1,1)$ of the $d=3$ $\mathcal{N}=3$ flavored Chern-Simons-matter theory. In the dual gravity side, we analyze the M5-brane filling ${\mathrm{AdS}}_{3}$ inside ${\mathrm{AdS}}_{4}$ and derive the quantized Hall conductivity of the dual gauge theory. In the gauge theory side, this M5-brane intersects the gauge theory at the codimension-one defect.

We elaborated the gravitational collapse of a self-gravitating complex charged scalar field in the context of the low-energy limit of the string theory, the so-called dilaton gravity. We begin with the regular spacetime and follow the evolution through the formation of an apparent horizon and the final central singularity., 36 pages, 51 figures, to be published in Phys.Rev.D15

In a recent paper published in this journal, Almeida and collaborators [Phys. Rev. D \textbf{79}, 125022 (2009)] analyze the issue of fermion localization of fermions on a brane constructed from two scalar fields coupled with gravity (Bloch brane model). In this meritorious research the simplest Yukawa coupling $\eta\bar{\Psi}\phi\chi\Psi$ was considered. In that work does not analyze the zero mode in details. In this paper, the localization of fermions on two-field thick branes is reinvestigated. It is found that the simplest Yukawa coupling does not support the localization of fermions on the brane. In addition, the problem of fermion localization for some other Yukawa couplings are analyzed. It is shown that the zero mode for left-handed and right-handed fermions can be localized on the brane depending on the values for the coupling constant $\eta$ and the Bloch brane's parameter $a$., Comment: 14 pages, 11 figures

QCD string is formed at the distances larger than the confinement scale and can be described by the Polchinski--Strominger effective string theory with a nonpolynomial action, which has nevertheless a well-defined semiclassical expansion around a long-string ground state. We utilize modern ideas about the Wilson-loop/scattering-amplitude duality to calculate scattering amplitudes and show that the expansion parameter in the effective string theory is small in the Regge kinematical regime. For the amplitudes we obtain the Regge behavior with a linear trajectory of the intercept (d-2)/24 in d dimensions, which is computed semiclassically as a momentum-space Luscher term, and discuss an application to meson scattering amplitudes in QCD., Comment: 24pp., 1 figure; v2: 1 reference & 1 acknowledgment added; v3: to appear in PRD

In this work we present 3-algebraic constructions and representations for three-dimensional N = 5 supersymmetric Chern-Simons theories, and show how they relate to theories with additional supersymmetries. The N = 5 structure constants give theories with Sp(2N) \times SO(M) gauge symmetry, as well as more exotic symmetries known from gauged supergravity. We find explicit lifts from N = 6 to 8, and N = 5 to 6 and 8, for appropriate gauge groups., 23 pages. Published version. References corrected

We assume that the early universe is homogeneous, anisotropic, and is dominated by the mutually BPS 22 ′ 55 ′ intersecting branes of M theory. The spatial directions are all taken to be toroidal. Using analytical and numerical methods, we study the evolution of such an universe. We find that, asymptotically, three spatial directions expand to infinity and the remaining spatial directions reach stabilised values. Any stabilised values can be obtained by a fine tuning of initial brane densities. We give a physical description of the stabilisation mechanism. Also, from the perspective of four dimensional spacetime, the effective four dimensional Newton’s constant G4 is now time varying. Its time dependence will follow from explicit solutions. We find in the present case that, asymptotically, G4 exhibits characteristic log periodic oscillations.

We show that the central charge of the Liouville and Toda theories of type A, D, and E can be reproduced by equivariantly integrating the anomaly eight-form of the corresponding six-dimensional N=(0,2) theories, which describe the low-energy dynamics of M5-branes.

We construct vertex operators for massless higher spin fields in RNS superstring theory and compute some of their three-point correlators, describing gauge-invariant cubic interactions of the massless higher spins. The Fierz-Pauli on-shell conditions for the higher spins (including tracelessness and vanishing divergence) follow from the BRST-invariance conditions for the vertex operators constructed in this paper. The gauge symmetries of the massless higher spins emerge as a result of the BRST nontriviality conditions for these operators, being equivalent to transformations with the traceless gauge parameter in the Fronsdal's approach. The gauge invariance of the interaction terms of the higher spins is therefore ensured automatically by that of the vertex operators in string theory. We develop general algorithm to compute the cubic interactions of the massless higher spins and use it to explicitly describe the gauge-invariant interaction of two $s=3$ and one $s=4$ massless particles., Comment: 33 pages, derivation of gauge transformations for higher spin fields from BRST conditions revised, typos corrected, acknowledgement and references added

We investigate the interaction between a flat membrane and pointlike graviton in the plane-wave matrix model. The one-loop effective potential in the large-distance limit is computed and is shown to be of r{sup -3} type where r is the distance between two objects. This type of interaction has been interpreted as the one incorporating the smearing effect due to the configuration of a flat membrane in a plane-wave background. Our results support this interpretation and provide more evidence about it.

We propose another method to compute the Casimir force in noncommutative Randall-Sundrum braneworld model considered by K. Nouicer and Y. Sabri recently. Our method can be used to compute the Casimir force to any order in the noncommutative parameter. Contrary to the claim made by K. Nouicer and Y. Sabri that repulsive Casimir force can appear in the first order approximation, we show that the Casimir force is always attractive at any order of approximation., 4 pages. Brief report. Accepted by Phys. Rev. D

If the second Betti number b{sub 2} of a Sasaki-Einstein manifold Y{sup 7} does not vanish, then M-theory on AdS{sub 4}xY{sup 7} possesses 'topological' U(1){sup b}{sub 2} gauge symmetry. The corresponding Abelian gauge fields come from three-form fluctuations with one index in AdS{sub 4} and the other two in Y{sup 7}. We find black membrane solutions carrying one of these U(1) charges. In the zero-temperature limit, our solutions interpolate between AdS{sub 4}xY{sup 7} in the UV and AdS{sub 2}xR{sup 2}xsquashed Y{sup 7} in the IR. In fact, the AdS{sub 2}xR{sup 2}xsquashed Y{sup 7} background is by itself a solution of the supergravity equations of motion. These solutions do not appear to preserve any supersymmetry. We search for their possible instabilities and do not find any. We also discuss the meaning of our charged membrane backgrounds in a dual quiver Chern-Simons gauge theory with a global U(1) charge density. Finally, we present a simple analytic solution which has the same IR but different UV behavior. We reduce this solution to type IIA string theory, and perform T-duality to type IIB. The type IIB metric turns out to be a product of the squashed Y{sup 7} and the extremal Banados-Teitelboim-Zanelli black hole.more » We discuss an interpretation of this type IIB background in terms of the (1+1)-dimensional conformal field theory on D3-branes partially wrapped over the squashed Y{sup 7}.« less

We present a simple two-field model of inflation and show how to embed it in string theory as a straightforward generalization of axion monodromy models. Phenomenologically, the predictions are equivalent to those of chaotic inflation, and, in particular, include observably large tensor modes. The whole high-scale large-field inflationary dynamics takes place within a region of field space that is parametrically sub-Planckian in diameter, hence improving our ability to control quantum corrections and achieve slow-roll inflation.

We describe a possible realization of the spontaneous baryogenesis mechanism in the context of extra-dimensional string cosmology and specifically in the string gas scenario., arXiv admin note: substantial text overlap with 0808.0746 by different author

We consider how to take an orbifold reduction for the multiple M2-brane theory recently proposed by Bagger and Lambert, and discuss its relation to Chern-Simons theories. Starting from the infinite dimensional 3-algebra realized as the Nambu bracket on a 3-torus, we first suggest an orbifolding prescription for various fields. Then we introduce a second truncation, which effectively reduces the internal space to a 2-torus. Eventually one obtains a large-N limit of Chern-Simons gauge theories coupled to matter fields. We consider an abelian orbifold C^4/Z_n, and illustrate how one can arrive at the N=6 supersymmetric theories with gauge groups U(N) x U(N) and Chern-Simons levels (k,-k), as recently constructed by Aharony, Bergman, Jafferis and Maldacena., 20 pages; v3. major revision, title and abstract changed. to appear in Phys.Rev.D

We study correlation functions in (0+1)-dimensional maximally supersymmetric U(N) gauge theory, which represents the low-energy effective theory of D0-branes. In the large-N limit, the gauge-gravity duality predicts power-law behaviors in the infrared region for the two-point correlation functions of operators corresponding to supergravity modes. We evaluate such correlation functions on the gauge theory side by the Monte Carlo method. Clear power-law behaviors are observed at N=3, and the predicted exponents are confirmed consistently. Our results suggest that the agreement extends to the M-theory regime, where the supergravity analysis in 10 dimensions may not be justified a priori., 4 pages, 3 figures

We describe hadronization events, using the AdS/CFT Correspondence, which display many of the qualitative features expected in QCD. In particular we study the motion of strings with separating end points in a back-reacted hard wall geometry. The solutions show the development of a linear QCD-like string. The end points oscillate in the absence of string breaking. We introduce string breaking by hand and evolve the new state forward in time to observe the separation of two string segments. A kink associated with this breaking evolves to the end points of the string inducing rho meson production. We explicitly compute the rho meson production at the end point., 15 pages, 11 jpg figures, added references

We study the scattering of noncommutative vortices, based on the noncommutative field theory developed in [Phys. Rev. D 75, 045009 (2007)], as a way to understand the interaction of cosmic strings. In the center-of-mass frame, the effects of noncommutativity vanish, and therefore the reconnection of cosmic strings occurs in an identical manner to the commutative case. However, when scattering occurs in a frame other than the center-of-mass frame, strings still reconnect but the well known 90-degree scattering no longer need correspond to the head on collision of the strings, due to the breakdown of Lorentz invariance in the underlying noncommutative field theory., 18 pages, 2 figures

In M(atrix) theory, there exist membranes and longitudinal 5-branes (L5-branes) as extended objects. Transverse components of these brane solutions are known to be described by fuzzy CP^k (k=1,2), where k=1 and k=2 correspond to spherical membranes and L5-branes of CP^2 \times S^1 world-volume geometry, respectively. In addition to these solutions, we here show the existence of L7-branes of CP^3 \times S^1 geometry, introducing extra potentials to the M(atrix) theory Lagrangian. As in the cases of k=1,2, the L7-branes (corresponding to k=3) also break the supersymmetries of M(atrix) theory. The extra potentials are introduced such that the energy of a static L7-brane solution becomes finite in the large N limit where N represents the matrix dimension of fuzzy CP^3. As a consequence, fluctuations from the L7-branes are suppressed, which effectively describes compactification of M(atrix) theory down to 7 dimensions. We show that one of the extra potentials can be considered as a matrix-valued 7-form. The presence of the 7-form in turn supports a possibility of Freund-Rubin type compactification. This suggests that our modification of M(atrix) theory can also lead to a physically interesting matrix model in four dimensions. In hope of such a possibility, we further consider compactification of M(atrix) theory down to fuzzy S^4 which can be defined in terms of fuzzy CP^3. Along the way, we also find a new L5-brane solution to M(atrix) theory which has purely spherical geometry in the transverse directions., 24 pages; v2. current address added; v3. extensively rewritten, published version

Using the recently proposed new solution generating technique, we construct the charged version of the Pomeranski-Senkov doubly rotating black ring in the $U(1{)}^{3}$ five-dimensional supergravity. For arbitrary values of charges the solution is unbalanced, but the Dirac-Misner string is removed when two of the charges are set to zero. In this particular case our solution can be uplifted to some solutions of six-dimensional vacuum gravity.

Analytical solutions of Maxwell equations in background spacetime of a black hole in a braneworld immersed in an external uniform magnetic field have been found. The influence of both magnetic and brane parameters on the effective potential of the radial motion of a charged test particle around a slowly rotating black hole in a braneworld immersed in a uniform magnetic field has been investigated by using the Hamilton-Jacobi method. An exact analytical solution for dependence of the radius of the innermost stable circular orbits (ISCO) ${r}_{\mathrm{ISCO}}$ from the brane parameter for the motion of a test particle around a nonrotating isolated black hole in a braneworld has been derived. It has been shown that the radius ${r}_{\mathrm{ISCO}}$ is monotonically growing with the increase of the module of the brane tidal charge. A comparison of the predictions on ${r}_{\mathrm{ISCO}}$ of the braneworld model and of the observational results of ISCO from relativistic accretion disks around black holes provided the upper limit for the brane tidal charge $\ensuremath{\lesssim}{10}^{9}\text{ }\text{ }{\mathrm{cm}}^{2}$.

In this paper we study the effect of spacetime noncommutativity in the 5-dimensional Randall-Sundrum brane worlds on the Casimir force acting on a pair of parallel plates. We show that the presence of a noncommutative scale length affects the nature of the Casimir force for small plate separation. Using accurate experimental bounds for the Casimir force in parallel plate geometry, we find an upper bound for the noncommutative cutoff of the order of $10^{3}$ TeV, and that the size of the interbrane distance in RSI model is approximately given by $kR\lesssim20.5$ and $kR\lesssim18.4$ for $k=10^{19}$ GeV and $k=10^{16}$GeV, respectively., 20 pages, 5 figures, accepted for publication in Phys. Rev. D

In arXiv:0901.3543, the simplest Yukawa coupling $\eta\bar{\Psi}\phi\chi\Psi$ was considered for a two-scalar-generated Bloch brane model. Fermionic resonances for both chiralities were obtained, and their appearance is related to branes with internal structure. Inspired on this result, we investigate the localization and resonance spectrum of fermions on a one-scalar-generated $dS$ thick brane with a class of scalar-fermion couplings $\eta\bar{\Psi}\phi^k\Psi$ with positive odd integer $k$. A set of massive fermionic resonances for both chiralities are obtained when provided large couple constant $\eta$. We find that the masses and life-times of left and right chiral resonances are almost the same, which demonstrates that it is possible to compose massive Dirac fermions from the left and right chiral resonances. The resonance with lower mass has longer life-time. For a same set of parameters, the number of resonances increases with $k$ and the life-time of the lower level resonance for larger $k$ is much longer than the one for smaller $k$., Comment: 23 pages, 35 figures, discussion and references added, to appear in PRD

We derive exact solutions of the seven-dimensional Einstein-Maxwell equations for a spacetime exhibiting Poincare invariance along four-dimensions and spherical symmetry in the extra-dimensions. Such topology generically arises in the context of braneworld models. Our solutions generalise previous results on Ricci-flat spacetimes admitting the two-sphere and are shown to include wormhole configurations. A regular coordinate system suitable to describe the whole spacetime is singled-out and we discuss the physical relevance of the derived solutions., 14 pages, 8 figures, uses RevTeX. Physical discussion clarified, wormhole solutions added. References added