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Dans le cadre du traitement des fractures fémorales comminutives diaphysaires chez le chien de petite taille selon le concept d'ostéosynthèse biologique, cette étude se propose de comparer 6 montages clou/plaque constitués d'une plaque VCP 2.0/2.07 et d'un clou centro-médullaire, différents par le nombre et l'implantation des vis mono ou bicorticales. Chaque montage a été testé in vitro en torsion sur 10 fémurs de chien afin de comparer leur raideur globale. Les résultats ont montré que le nombre de vis avait une plus grande influence que le nombre de corticales pontées. Compte tenu de ces résultats et de l'encombrement des vis, la configuration associant une vis bicorticale et trois vis monocroticales nous semble constituer le meilleur compromis.

The algebraic structure of the rank two Racah algebra is studied in detail. We provide an automorphism group of this algebra, which is isomorphic to the permutation group of five elements. This group can be geometrically interpreted as the symmetry of a folded icosidodecahedron. It allows us to study a class of equivalent irreducible representations of this Racah algebra. They can be chosen symmetric so that their transition matrices are orthogonal. We show that their entries can be expressed in terms of Racah polynomials. This construction gives an alternative proof of the recurrence, difference and orthogonal relations satisfied by the Tratnik polynomials, as well as their expressions as a product of two monovariate Racah polynomials. Our construction provides a generalization of these bivariate polynomials together with their properties., 40 pages, 4 figures. Several signs corrected and some proofs clarified

We explore the phenomena of absorption/emission of solitons by an integrable boundary for the nonlinear Schr\"odinger equation on the half-line. This is based on the investigation of time-dependent reflection matrices which satisfy the boundary zero curvature equation. In particular, this leads to absorption/emission processes at the boundary that can take place for solitons and higher-order solitons. As a consequence, the usual charges on the half-line are no longer conserved but we show explicitly how to restore an infinite set of conserved quantities by taking the boundary into account. The Hamiltonian description and Poisson structure of the model are presented, which allows us to derive for the first time a classical version of the boundary algebra used originally in the context of the quantum nonlinear Schr\"odinger equation., Comment: 22 pages, 4 figures. Authors' accepted version in Physica D

We introduce a model with diffusive and evaporation/condensation processes, depending on 3 parameters obeying some inequalities. The model can be solved in the sense that all correlation functions can be computed exactly without the use of integrability. We show that the mean field approximation is not exact in general. This can be shown by looking at the analytical expression of the two-point correlation functions, that we provide. We confirm our analysis by numerics based on direct diagonalisation of the Markov matrix (for small values of the number of sites) and also by Monte-Carlo simulations (for a higher number of sites). Although the model is symmetric in its diffusive rates, it exhibits a left / right asymmetry driven by the evaporation/condensation processes. We also argue that the model can be taken as a one-dimensional model for catalysis or fracturing processes., Comment: 23 pages, 11 figures

We perform the first one-loop electroweak corrections for $2 \to 3$ processes for dark matter annihilation. These are the dominant processes that enter the computation of the relic density for the low mass region of the inert doublet model (IDM) when annihilations to two on-shell vector bosons are closed. The impact of the one-loop corrections are important as they involve, through rescattering effects, not only a dependence on the parameter controlling the dark sector, not present if a calculation at tree-level is conducted, but also on the renormalisation scale. These combined effects should be taken into account in analyses based on tree-level cross-sections of the relic density calculations, as a theoretical uncertainty which we find to be much larger than the cursory $\pm 10\%$ uncertainty that is routinely assumed, independently of the model parameters., v1: 18 pages, 8 figures and 2 tables

The present paper is the first in a series that addresses the calculation of the full one-loop corrections of dark matter (DM) annihilation cross-sections in the low mass region of the inert doublet model (IDM). We first review the renormalisation of the model both in a fully on-shell (OS) scheme and a mixed scheme combining on-shell (for the masses) and a $\overline{{\rm MS}}$ approach when the partial invisible width is closed and does not allow the use of a full OS scheme. The scale dependence introduced by the mixed scheme is shown to be tracked through an analysis of a parametrisation of the tree-level cross-section and the $\beta$ constant of a specific coupling. We discuss how to minimise the scale dependence. The theoretical uncertainty brought by the scale dependence leads us to introduce a new criterion on the perturbativity of the IDM. This criterion further delimits the allowed parameter space which we investigate carefully by including a host of constraints, both theoretical and experimental, including in particular, new data from the LHC. We come up with a set of benchmark points that cover three different mechanisms for a viable relic density of DM: {\it i)} a dominance of co-annihilation into a fermion pair, { \it ii)} annihilation into 2 vector bosons of which one is off-shell that requires the calculation of a $2 \to 3$ process at one-loop, {\it iii)} annihilation that proceeds through the very narrow standard model Higgs resonance. Since the $2 \to 3$ vector boson channel features in all three channels and is essentially a build up on the simpler annihilation to OS vector bosons, we study the latter in detail in the present paper. We confirm again that the corrected cross-sections involve a parameter that represents rescattering in the dark sector that a tree-level computation in not sensitive to., Comment: v1: 33 pages, 5 figures and 4 tables

We examine the relic density of the light mass dark matter region in the inert doublet model (IDM) when the dominant process is due to co-annihilation between the lightest neutral scalars of the model. The full one-loop electroweak corrections are computed in an on-shell scheme and are found to be well approximated as an effective cross-section expressed in terms of $Z$-observables. The electroweak corrections to the subdominant process which consists of an annihilation into an on-shell $W$ and an off-shell $W$, that is calculated as a annihilation into a 3-body final state, is also performed. The latter reveals an important dependence on a parameter that describes the self-interaction of the new scalars (solely within the dark sector), a parameter which is not accessible in tree-level calculations of standard model (SM)-IDM interactions., v1: 14 pages, 9 figures and 2 tables

One-loop electroweak corrections to the annihilation cross-sections of dark matter in the Higgs resonance region of the inert doublet model (IDM) are investigated. The procedure of how to implement the width of the Higgs in order to regularise the amplitude both at tree-level and at one-loop together with the renormalisation of a key parameter of the model, are thoroughly scrutinised. The discussions go beyond the application to the relic density calculation and also beyond the IDM so that addressing these technical issues can help in a wider context. We look in particular at the dominant channels with the $b \bar b$ final state and the more involved 3-body final state, $W f \bar f^\prime$, where both a resonance and an anti-resonance, due to interference effects, are present. We also discuss how to integrate over such configurations when converting the cross-sections into a calculation of the relic density., Comment: v1: 20 pages, 8 figures and 2 tables

Extended Higgs sectors have been studied extensively in context of dark matter phenomenology in tandem with other aspects. In this study, we compute radiative corrections to the dark matter-Higgs portal coupling, which is in fact a common feature of all scalar dark matter models irrespective of the hypercharge of the multiplet from which the dark matter candidate emerges. We select the popular inert doublet model (IDM) as a prototype in order to demonstrate the impact of the next-to-leading order corrections, thereby probing the plausibility of extending the allowed parameter space through quantum effects. Given that the tree level portal coupling is a \emph{prima facie} free parameter, the percentage change from loop effects can be large. This modifies the dark matter phenomenology at a quantitative level. It also encourages one to include loop corrections to all other interactions that are deemed relevant in this context., v3: 26 pages, 9 figures and 1 table; some typos fixed; matches published version

In this paper we study the statistical properties of a reversible cellular automaton in two out-of-equilibrium settings. In the first part we consider two instances of the initial value problem, corresponding to the inhomogeneous quench and the local quench. Our main result is an exact matrix product expression of the time evolution of the probability distribution, which we use to determine the time evolution of the density profiles analytically. In the second part we study the model on a finite lattice coupled with stochastic boundaries. Once again we derive an exact matrix product expression of the stationary distribution, as well as the particle current and density profiles in the stationary state. The exact expressions reveal the existence of different phases with either ballistic or diffusive transport depending on the boundary parameters.

We consider the trigonometric classical $r$-matrix for $\mathfrak{gl}_N$ and the associated quantum Gaudin model. We produce higher Hamiltonians in an explicit form by applying the limit $q\to 1$ to elements of the Bethe subalgebra for the $XXZ$ model., 14 pages

Explicit formulas for Segal-Sugawara vectors associated with the simple Lie algebra $\mathfrak{g}$ of type $G_2$ are found by using computer-assisted calculations. This leads to a direct proof of the Feigin-Frenkel theorem describing the center of the corresponding affine vertex algebra at the critical level. As an application, we give an explicit solution of Vinberg's quantization problem by providing formulas for generators of maximal commutative subalgebras of $U(\mathfrak{g})$. We also calculate the eigenvalues of the Hamiltonians on the Bethe vectors in the Gaudin model associated with $\mathfrak{g}$., 26 pages

We study a class of multi-species ASEP with open boundaries. The boundaries are chosen in such a way that all species of particles interact non-trivially with the boundaries and are present in the stationary state. We give the exact expression of the stationary state in a matrix product form and we compute its normalisation. Densities and currents for the different species are then computed in term of this normalisation., 26 pages

A new measurement of a spatially extended gamma-ray signal from the center of the Andromeda galaxy (M31) has been recently published by the Fermi-LAT collaboration, reporting that the emission broadly resembles the so-called Galactic center excess (GCE) of the Milky Way (MW). At the same time, evidence is accumulating on a millisecond pulsar (MSPs) origin for the GCE. These elements prompt us to compare the mentioned observations with what is, perhaps, the simplest model for an MSP population, solely obtained by rescaling of the MSP luminosity function determined in the local MW disk via the respective stellar mass of the systems. It is remarkable that without free fitting parameters, this model can account for both the energetics and the morphology of the GCE within uncertainties. For M31, the estimated luminosity due to primordial MSPs is expected to contribute only about a quarter of the detected emission, although a dominant contribution cannot be excluded given the large uncertainties. If correct, the model predicts that the M31 disk emission due to MSP is not far below the present upper bound. We also discuss a few refinements of this simple model. In particular, we use the correlation between globular cluster gamma-ray luminosity and stellar encounter rate to gauge the dynamical MSP formation in the bulge. This component is expected to contribute to the GCE only at a level $\lesssim 5\%$, but it may be of some importance in explaining the signal's morphology in the inner region of the Galaxy. We also comment on some effects which may lead to violations of the simple scaling used, on alternative models, and on future perspectives for improved diagnostics., 12 pages, 5 figures, accepted for publication in ApJ

In contrast to the decay products ensuing from a fast moving particle which are collimated along the original direction of the parent, those from a slow moving particle are distributed over a wide region. In the context of searches for heavy long-lived particles (LLP) at the Large Hadron Collider (LHC), we quantitatively demonstrate, using a few benchmark models, that objects which emerge from a secondary vertex due to the decay of an LLP at the TeV scale can be at large angular separations with respect to the direction of the parent LLP. A fraction of the decay products, the backward moving objects (\textit{BMO}s), can even go in the backward direction. These will give rise to striking signatures in the detectors at the LHC as these particles will traverse different layers of the detector {\it outside-in} towards the direction of the beam-pipe. Based on a simple geometrical modelling of the detector, we give examples of how this effect translates into the fraction of energy deposited in the tracker, from particles coming as far as from the hadron calorimeter, as well as those that could be entering from outside the detector into the muon chamber. The largest effect is from LLP candidates that come to rest inside the detector, such as the stopped $R$-hadrons. But the results are promising even in the case of not so heavy LLPs and/or when some of the available energy is carried by a massive invisible daughter. This urges us to look more in details at these unusual signatures, taking into account the particularities of each layer that constitutes the detector. From the \textit{BMO} perspective, we review how each layer of the detector could be exploited and what improvements can be made to enhance the shower shapes and the timing information, for instance. We also argue that the cosmic ray events, the most important background, can be easily dealt with., v2; 22 pages, 4 figures, 1 table; version vastly expanded with more details; title changed to "A novel signature for long-lived particles at the LHC" in the journal version; version accepted for publication in PRD; conclusions updated

Dark matter (DM) and neutrinos are the two most compelling pieces of evidence of new physics beyond the Standard Model of Particle Physics but these are often treated as belonging to two different sectors. Yet DM-neutrino interactions are known to have cosmological consequences. Here, we study the scenario of a scalar DM candidate coupled to left-handed neutrinos via a Dirac mediator. We determine the mass of a DM candidate that yields the right DM relic abundance in a thermal scenario and it is consistent with large-scale structure formation. In order to satisfy both constraints, a complex DM candidate should have a mass larger than $8.14$ keV while the mass of a real DM candidate should be above $18.1$ eV, independently of the value of the DM-neutrino coupling., Poster presented at NuPhys2016 (London, 12-14 December 2016). 4 pages, LaTeX, 2 png figures

I give an overview of recent theoretical results for exclusive Higgs-production cross sections, focusing in particular on processes where precise predictions will be relevant in the near future., 9 pages, 3 figures. Submitted to the proceedings of the 5th annual Large Hadron Collider Physics conference, LHCP2017, 15-20 May, 2017, Shanghai, China

International audience; We study Bethe vectors of integrable models based on the super-Yangian$Y(\mathfrak{gl}(m|n))$. Starting from the super-trace formula, we exhibitrecursion relations for these vectors in the case of $Y(\mathfrak{gl}(2|1))$and $Y(\mathfrak{gl}(1|2))$. These recursion relations allow to get explicitexpressions for the Bethe vectors. Using an antimorphism of the super-Yangian$Y(\mathfrak{gl}(m|n))$, we also construct a super-trace formula for dual Bethevectors, and, for $Y(\mathfrak{gl}(2|1))$ and $Y(\mathfrak{gl}(1|2))$super-Yangians, show recursion relations for them. Again, the latter allow usto get explicit expressions for dual Bethe vectors.

International audience; We propose an approach to probe new fundamental interactions using isotopeshift spectroscopy in atomic clock transitions. As an example we focus on theHiggs boson couplings to the building blocks of matter: the electron and the upand down quarks. We show that the attractive Higgs force between nuclei andtheir bound electrons, that is poorly constrained, might induce effects thatare larger than the current experimental sensitivities. We discuss how newinteractions between the electron and the neutrons may lead to measurablenon-linearities in a King plot comparison between isotope shifts of twodifferent transitions. Given state-of-the-art accuracy in frequency comparison,isotope shifts have the potential of being measured with sub-Hz accuracy, thuspotentially enabling the improvement of current limits on new fundamentalinteractions. Candidate atomic system for this measurement require twodifferent clock transitions and four zero nuclear spin isotopes. We identifyseveral systems that satisfy this requirement and also briefly discuss existingmeasurements. We consider the size of the effect related to the Higgs force andthe requirements for it to produce an observable signal.

International audience; We propose a novel strategy to constrain the bottom and charm Yukawacouplings by exploiting LHC measurements of transverse momentum distributionsin Higgs production. Our method does not rely on the reconstruction ofexclusive final states or heavy-flavour tagging. Compared to other proposals itleads to an enhanced sensitivity to the Yukawa couplings due to distortions ofthe differential Higgs spectra from emissions which either probe quark loops orare associated to quark-initiated production. We derive constraints using datafrom LHC Run I, and we explore the prospects of our method at future LHC runs.Finally, we comment on the possibility of bounding the strange Yukawa coupling.

We reveal a new mechanism of conformal symmetry breaking at Born level. It occurs in generalized form factors with several local operators and an on-shell state of massless particles. The effect is due to hidden singularities on collinear configurations of the momenta. This conformal anomaly is different from the holomorphic anomaly of amplitudes. We present a number of examples in four and six dimensions. We find an application of the new conformal anomaly to finite loop momentum integrals with one or more massless legs. The collinear region around a massless leg creates a contact anomaly, made visible by the loop integration. The anomalous conformal Ward identity for an $\ell-$loop integral is a 2nd-order differential equation whose right-hand side is an $(\ell-1)-$loop integral. We show several examples, in particular the four-dimensional scalar double box., Comment: 36 pages, 9 figures; reference added, typos corrected

We investigate the motion of electrically charged test particles inspacetimes with closed timelike curves, a subset of the black hole or wormholeReissner-Nordstr\"om-NUT spacetimes without periodic identification of time. Weshow that, while in the wormhole case there are closed worldlines inside apotential well, the wordlines of initially distant charged observers movingunder the action of the Lorentz force can never close or self-intersect. Thismeans that for these observers causality is preserved, which is an instance ofour weak chronology protection criterion.

We investigate the potential to probe physics beyond the Standard Model with isotope shift measurements of optical atomic clock transitions. We first derive the reach for generic new physics above the GeV scale at the effective field theory level, as well as estimate the limits on possible new spin-independent forces mediated by sub-GeV states coupled to electrons and neutrons. We also study the weak force and show that isotope shifts could provide strong constraints on the $Z^0$ couplings to valence quarks, which complement precision observables at LEP and atomic parity violation experiments. Finally, motivated by recent experimental hints of a new 750 GeV resonance in diphotons, we also consider the potential to probe its parity-preserving couplings to electrons, quarks and gluons with this method. In particular, combining the diphoton signal with indirect constraints from $g_e-2$ and isotope shifts in Ytterbium allows to probe the resonance coupling to electrons with unprecedented precision., 6 pages, 2 figures, 2 tables

In composite Higgs models (CHMs), electroweak precision data generically push colourless composite vector resonances to a regime where they dominantly decay into pairs of light top partners. This greatly attenuates their traces in canonical collider searches, tailored for narrow resonances promptly decaying into Standard Model final states. By reinterpreting the CMS same-sign dilepton (SS2$\ell$) analysis at the Large Hadron Collider (LHC), originally designed to search for top partners with electric charge $5/3$, we demonstrate its significant coverage over this kinematical regime. We also show the reach of the 13 TeV run of the LHC, with various integrated luminosity options, for a possible upgrade of the SS2$\ell$ search. The top sector of CHMs is found to be more fine-tuned in the presence of colourless composite resonances in the few TeV range., 9 pages, 5 figures. Minor corrections for publication in JHEP

Small-field inflation (SFI) is widely considered to be unnatural because an extreme fine-tuning of the initial condition is necessary for sufficiently large e-folding. In this paper, we show that the unnaturally-looking initial condition can be dynamically realised without any fine-tuning if the SFI occurs after rapid oscillations of the inflaton field and particle creations by preheating. In fact, if the inflaton field $\phi$ is coupled to another scalar field $\chi$ through the interaction $g^2 \chi^2 \phi^2$ and the vacuum energy during the small field inflation is given by $\lambda M^4$, the initial value can be dynamically set at $(\sqrt{\lambda}/g) M^2/M_{\rm pl}$, which is much smaller than the typical scale of the potential $M.$ This solves the initial condition problem in the new inflation model or some classes of the hilltop inflation models., Comment: 17 pages, 2 figures

We revisit a set of dark sector models, motivated by anomalies observed in $B$ decays and the muon anomalous magnetic moment, in the light of a recently reported diphoton excess around 750$\,$GeV. Interpreting the excess as a scalar resonance associated with the symmetry breaking sector of a dark gauge group, we show that a diphoton cross section of few fb can be accomodated, together with anomalies in $R_K$ and $g_\mu-2$ within a minimal dark sector model. The resulting prominent collider signatures are in the form of wide resonant signals into top and muon pair final states below $\sim1\,$TeV. The model further predicts a dark matter candidate, yet with a significantly underabundant relic density, unless produced by an appropriate non-thermal mechanism., Comment: 7 pages, 3 figures

We propose a new approach to the resummation of the transverse-momentum distribution of a high-mass colour-singlet system in hadronic collisions. The resummation is performed in momentum space and is free of kinematic singularities at small transverse momentum. We derive a formula accurate at the next-to-next-to-leading-logarithmic level, and present the first matched predictions to next-to-next-to-leading order for Higgs-boson production in gluon fusion at the LHC. This method can be adapted to all observables featuring kinematic cancellations in the infrared region., Comment: Minor changes to abstract and text, a few references added. First figure was changed to make its content clearer. The text referring to the plot was changed accordingly

We construct a hyperbolic modular double -- an algebra lying in between the Faddeev modular double for $U_q(sl_2)$ and the elliptic modular double. The intertwining operator for this algebra leads to an integral operator solution of the Yang-Baxter equation associated with a generalized Faddeev-Volkov lattice model introduced by the second author. We describe also the L-operator and finite-dimensional R-matrices for this model., 29 pages, 4 figures. v3: references added, to appear in Advanced Studies in Pure Mathematics

International audience; We study $\mathfrak{gl}(2|1)$ symmetric integrable models solvable by thenested algebraic Bethe ansatz. Using explicit formulas for the Bethe vectors wederive the actions of the monodromy matrix entries onto these vectors. We showthat the result of these actions is a finite linear combination of Bethevectors. The obtained formulas open a way for studying scalar products of Bethevectors.

International audience; We study scalar products of Bethe vectors in integrable models solvable bynested algebraic Bethe ansatz and possessing $\mathfrak{gl}(2|1)$ symmetry.Using explicit formulas of the monodromy matrix entries multiple actions ontoBethe vectors we obtain a representation for the scalar product in the mostgeneral case. This explicit representation appears to be a sum over partitionsof the Bethe parameters. It can be used for the analysis of scalar productsinvolving on-shell Bethe vectors. As a by-product, we obtain a determinant representation for the scalarproducts of generic Bethe vectors in integrable models with$\mathfrak{gl}(1|1)$ symmetry.

International audience; The center of our Galaxy provides a uniquely accessible laboratory. It is a rich environment of extreme density, velocity and tidal fields of stars. It is the closest example of a galactic nucleus and could give the opportunity to understand the role that massive black-holes play in the formation and evolution of galaxies. It could be used to test the effects of relativity and dark matter in the Galactic Center. If the central object is a black-hole such observation would be a milstone: the first direct proof that an event horizon, and therefore a black-hole exists. The next decade will be decisive in new discoveries.

International audience; We present a model of a gamma-ray burst (GRB) related to “very massive” stars. In the framework of our model, the GRB phenomenon is a result of helium burning in degenerate conditions in a massive star (≳130 M⊙), in which the thermal nuclear burning occurs in the deflagration regime and has a pulsating temporal pattern. The shock runs away from the burning (reaction) zone, which leads to the development of a coronal outflow (jet-like) structure. In our scenario the GRB observable prompt fast rise and decay part can be a result of photon propagation through the hot corona (Comptonization photosphere) of the star. On the other hand, the GRB afterglow is a cooling phase of the expanding and outflowing envelope. Presumably, the X-ray part of the GRB emergent spectrum is formed due to upscattering of soft photons of outer layers of the star off hot coronal electrons, and thus it should have a specific shape of the Comptonization spectrum.

We elaborate on a recently found $SU(5)$ relation confined to the up-(s)quark flavour space, that remains immune to large quantum corrections up to the TeV scale. We investigate the possibilities opened by this new window on the GUT scale in order to find TeV-scale $SU(5)$ tests realizable at the LHC. We present a variety of tests, which appear as relations among observables involving flavour violation or chirality flips and rely on the techniques of top polarimetry, charm-tagging, or Higgs detection from cascade decays. We discuss the cases of natural Supersymmetry and top-charm Supersymmetry as example cases. We find that $O(10)$ to $O(100)$ events are needed to obtain 50\% of relative precision at 3$\sigma$ significance for all proposed tests., Comment: 7 pages, 1 figure. To appear in the proceedings of the European Physical Society Conference on High Energy Physics 2015 (EPS-HEP 2015), Vienna, Austria, 22nd to 29th of July 2015

In Poulin and Serpico [Phys. Rev. Lett. 114, 091101 (2015)] we have recently argued that when the energy of a photon injected in the primordial plasma falls below the pair-production threshold, the universality of the non-thermal photon spectrum from the standard theory of electromagnetic cascades onto a photon background breaks down. We showed that this could reopen or widen the parameter space for an exotic solution to the 'lithium problem'. Here we discuss another application, namely the impact that this has on non-thermal big bang nucleosynthesis constraints from 4He, 3He and 2H, using the parametric example of monochromatic photon injection of different energies. Typically, we find tighter bounds than those existing in the literature, up to more than one order of magnitude. As a consequence of the non-universality of the spectrum, the energy-dependence of the photodissociation cross-sections is important. We also compare the constraints obtained with current level and future reach of cosmic microwave background spectral distortion bounds., 8 pages, 7 figures. v2: minor typographical corrections, extended comments and references

The top quark plays a central role in many New Physics scenarios and in understanding the details of Electro-Weak Symmetry Breaking. In the short- and mid-term future, top-quark studies will mainly be driven by the experiments at the Large Hadron Collider. Exploration of top quarks will, however, be an integral part of particle physics studies at any future facility and an $e^+ e^-$ collider will have a very comprehensive top-quark physics program. We discuss the possibilities of testing NP in the top-quark sector within a composite Higgs scenario through deviations from the Standard Model in top pair production for different Centre-of-Mass energy options of a future $e^+e^-$ machine. In particular, we focus on precision studies of the top-quark sector at a CM energy ranging from 370 GeV up to 3 TeV., Comment: 23 pages, 10 figures; v2: minor corrections, published on JHEP

Context: Features in the spectra of primary cosmic rays (CRs) provide invaluable information on the propagation of these particles in the Galaxy. In the rigidity region around a few hundred GV, such features have been measured in the proton and helium spectra by the PAMELA experiment and later confirmed with a higher significance by AMS-02. We investigate the implications of these datasets for the scenario in which CRs propagate under the action of self-generated waves. Aims: We show that the recent data on the spectrum of protons and helium nuclei as collected with AMS-02 and Voyager are in very good agreement with the predictions of a model in which the transport of Galactic CRs is regulated by self-generated waves. We also study the implications of the scenario for the boron-to-carbon ratio: although a good overall agreement is found, at high energy we find marginal support for a (quasi) energy independent contribution to the grammage, that we argue may come from the sources themselves Results: A break in the spectra of all nuclei is found at rigidity of a few hundred GV, as a result of a transition from self-generated waves to pre-existing waves with a Kolmogorov power spectrum. Neither the slope of the diffusion coefficient, nor its normalisation are free parameters. Moreover, at rigidities below a few GV, CRs are predicted to be advected with the self-generated waves at the local Alfv\'en speed. This effect, predicted in our previous work, provides an excellent fit to the Voyager data on the proton and helium spectra at low energies, providing additional support to the model., Comment: Submitted to A&A Research Note, 5 pages, 4 Figures. arXiv admin note: text overlap with arXiv:1306.2018

We show that the recently reported anomalies in $b\to s\mu^+\mu^-$ transitions, as well as the long-standing $g_\mu-2$ discrepancy, can be addressed simultaneously by a new massive abelian gauge boson with loop-induced coupling to muons. Such a scenario typically leads to a stable dark matter candidate with a thermal relic density close to the observed value. Dark matter in our model couples dominantly to leptons, hence signals in direct detection experiments lie well below the current sensitivity. The LHC, in combination with indirect detection searches, can test this scenario through distinctive signatures with muon pairs and missing energy., Comment: 10 pages, 7 figures, 1 table

We produce explicit generators of the classical W-algebras associated with the principal nilpotents in the simple Lie algebras of all classical types and in the exceptional Lie algebra of type $G_2$. The generators are given by determinant formulas in the context of the Poisson vertex algebras. We also show that the images of the W-algebra generators under the Chevalley-type isomorphism coincide with the elements defined via the corresponding Miura transformations., 37 pages

The morphology and characteristics of the so-called GeV gamma-ray excess detected in the Milky Way lead us to speculate about a possible common origin with the 511 keV line mapped by the SPI experiment about ten years ago. In the previous version of our paper, we assumed 30 GeV dark matter particles annihilating into $b \bar{b}$ and obtained both a morphology and a 511 keV flux (\phi_{511 keV} ~ 10^{-3} ph/cm^2/s) in agreement with SPI observation. However our estimates assumed a negligible number density of electrons in the bulge which lead to an artificial increase in the flux (mostly due to negligible Coulomb losses in this configuration). Assuming a number density greater than $n_e > 10^{-3} cm^{-3}$, we now obtain a flux of 511 keV photons that is smaller than \phi_{511 keV} ~ 10^{-6} ph/cm^2/s and is essentially in agreement with the 511 keV flux that one can infer from the total number of positrons injected by dark matter annihilations into $b \bar{b}$. We thus conclude that -- even if 30 GeV dark matter particles were to exist-- it is impossible to establish a connexion between the two types of signals, even though they are located within the same 10 deg region in the galactic centre., Comment: 2 pages; 1 figure

This work presents several works related to the impact of neutrinos in cosmology. We study the impact on the Cosmic Microwave Background of several neutrino-related parameters (mass, abundance, neutrino-antineutrino asymmetry, non-thermal distorsions, non-standard couplings with other species, mass and abundance of additional sterile neutrinos). We present new numerical methods for computing these effects efficiently. We use current data to derive several new bounds on these parameters, and finally, we study the sensitivity of future cosmological experiments to these quantities.

The experimental situation of Dark Matter Direct Detection has reached an exciting cross-roads, with potential hints of a discovery of Dark Matter (DM) from the CDMS, CoGeNT, CRESST-II and DAMA experiments in tension with null-results from xenon-based experiments such as XENON100 and LUX. Given the present controversial experimental status, it is important that the analytical method used to search for DM in Direct Detection experiments is both robust and flexible enough to deal with data for which the distinction between signal and background points is difficult, and hence where the choice between setting a limit or defining a discovery region is debatable. In this article we propose a novel (Bayesian) analytical method, which can be applied to all Direct Detection experiments and which extracts the maximum amount of information from the data. We apply our method to the XENON100 experiment data as a worked example, and show that firstly our exclusion limit at 90% confidence is in agreement with their own for the 225 Live Days data, but is several times stronger for the 100 Live Days data. Secondly we find that, due to the two points at low values of S1 and S2 in the 225 days data-set, our analysis points to either weak consistency with low-mass Dark Matter or the possible presence of an unknown background. Given the null-result from LUX, the latter scenario seems the more plausible., v3: Updated to match version accepted to PRD. Contains a discussion now also of the LUX experiment. 10 pages, 3 figures

The cold dark matter (CDM) model faces persistent challenges on small scales.In particular, taken at face value, the model significantly overestimates thenumber of satellite galaxies around the Milky Way. Attempts to solve thisproblem remain open to debate and have even led some to abandon CDM altogether.However, current simulations are limited by the assumption that dark matterfeels only gravity. Here, we show that including interactions between CDM andradiation (photons or neutrinos) leads to a dramatic reduction in the number ofsatellite galaxies, alleviating the Milky Way satellite problem and indicatingthat physics beyond gravity may be essential to make accurate predictions ofstructure formation on small scales. The methodology introduced here givesconstraints on dark matter interactions that are significantly improved overthose from the cosmic microwave background.

International audience; The problem of nucleosynthesis was studied within an aspherical supernova model. The explosive burning was computed in a star of 25 M ☉ initial mass on its final stage of evolution. The chemical composition of a presupernova was taken from realistic evolutionary computations. A piecewise parabolic method on a local stencil was applied to simulate the hydrodynamics of the explosion. The gravity was recomputed by a Poisson solver on a fine grid as the explosion developed. A detailed yield of chemical elements was performed as a post-processing step using the tracer particles method. The produced nuclei formed a layer-like structure enclosing large fragments of nickel and iron-group isotopes that were pushed away from the central region by an explosion along the polar direction. The light nuclei were preferentially moving along the equatorial plane forming a torus-like structure.

The simplicity of maximally supersymmetric Yang-Mills theory makes it an ideal theoretical laboratory for developing computational tools, which eventually find their way to QCD applications. In this contribution, we continue the investigation of a recent proposal by Basso, Sever and Vieira, for the nonperturbative description of its planar scattering amplitudes, as an expansion around collinear kinematics. The method of arXiv:1310.5735, for computing the integrals the latter proposal predicts for the leading term in the expansion of the 6-point remainder function, is extended to one of the subleading terms. In particular, we focus on the contribution of the 2-gluon bound state in the dual flux tube picture, proving its general form at any order in the coupling, and providing explicit expressions up to 6 loops. These are included in the ancillary file accompanying the version of this article on the arXiv., Comment: 6 pages, 1 figure, 1 ancillary file; based on talk given at Moriond QCD 2014. v2: typo corrections, addition of an appendix on the contribution of two same-helicity gluons; to appear in Int.J.Mod.Phys. A

International audience; Theoretical predictions for the cosmic antiproton spectrum currently fallshort of the corresponding experimental level of accuracy. Among the mainsources of uncertainty are the antiproton production cross sections in cosmicray inelastic interactions. We analyse existing data on antiproton productionin $pp$ scattering, including for the first time the measurements performed bythe NA49 Collaboration. We compute the antiproton spectrum finding that in theenergy range where data are available (antiproton energies of about 4-550 GeV)different approaches lead to almost equivalent results, with an uncertainty of10-20\%. Extrapolations outside this region lead to different estimates, withthe uncertainties reaching the 50\% level around $1$ TeV, degrading thediagnostic power of the antiproton channel at those energies. We also commenton the uncertainties in the antiproton production source term coming fromnuclei heavier than protons and from neutrons produced in $pp$ scatterings, andpoint out the need for dedicated experimental campaigns for all processesinvolving antiproton production in collisions of light nuclei.

We present a new approach to computing event shape distributions or, more precisely, charge flow correlations in a generic conformal field theory (CFT). These infrared finite observables are familiar from collider physics studies and describe the angular distribution of global charges in outgoing radiation created from the vacuum by some source. The charge flow correlations can be expressed in terms of Wightman correlation functions in a certain limit. We explain how to compute these quantities starting from their Euclidean analogues by means of a non-trivial analytic continuation which, in the framework of CFT, can elegantly be performed in Mellin space. The relation between the charge flow correlations and Euclidean correlation functions can be reformulated directly in configuration space, bypassing the Mellin representation, as a certain Lorentzian double discontinuity of the correlation function integrated along the cuts. We illustrate the general formalism in N=4 SYM, making use of the well-known results on the four-point correlation function of half-BPS scalar operators. We compute the double scalar flow correlation in N=4 SYM, at weak and strong coupling and show that it agrees with known results obtained by different techniques. One of the remarkable features of the N=4 theory is that the scalar and energy flow correlations are proportional to each other. Imposing natural physical conditions on the energy flow correlations (finiteness, positivity and regularity), we formulate additional constraints on the four-point correlation functions in N=4 SYM that should be valid at any coupling and away from the planar limit., Comment: 40 pages, 1 figure; v2: typos corrected

International audience; We study the impact of the existence of an eV-mass scale sterileneutrino---with parameters in the ballpark of what is required to fit thelaboratory anomalies---on the early time profile of the electron neutrino andantineutrino fluxes associated to a core-collapse supernova (SN). Inparticular, we focus on the universal feature of neutronization burst expectedin the first tens of ms of the signal: provided that a detector with sufficientsensitivity is available, it is well-known that in the 3 neutrino framework thedetection of the neutronization burst in neutrino channel would signal invertedmass hierarchy. This conclusion is dramatically altered in the presence of asterile neutrino: we study here both analytically and numerically the region inparameter space where this characteristic signal disappears, mimicking normalhierarchy expectations. Conversely, the detection of a peak consistent withexpectations for inverted mass hierarchy would exclude the existence of asterile state over a much wider parameter space than what required bylaboratory anomalies fits, or even probed by detectors coming on-line in thenear future. Additionally, we show the peculiar alteration in the energy-timedouble differential flux, with a delayed peak appearing for kinematicalreasons, which might offer a remarkable signature in case of favorableparameters and for a high statistics detection of a Galactic SN. We alsocomment on additional potentially interesting effects in the electronantineutrino channel, if more than one angle in the active-sterile sector isnon-vanishing. As an ancillary result that we derived in the technicalresolution of the equations, in an appendix we report the Cayley-Hamiltonformalism for the evolution of a four neutrino system in matter, generalizingexisting results in the literature.

We study quark flavour violation (QFV) in the squark sector of the Minimal Supersymmetric Standard Model (MSSM). We assume mixing between the second and the third squark generations, i.e. sc_R-st_{L,R} mixing mixing. We focus on QFV effects in bosonic squark decays, in particular on the decay into the lightest Higgs boson h0, su_2 -> su_1 h0, where su_{1,2} are the lightest up-type squarks. We show that the branching ratio of this QFV decay can be quite large (up to 50 %) due to large QFV trilinear couplings, and large sc_R-st_{L, R} and st_L-st_R mixing, despite the strong constraints on QFV from B meson data. This can result in characteristic QFV final states with significant rates at LHC (14 TeV), such as pp -> gluino gluino X -> t + h0 + 3jets + Etmiss + X and pp -> gluino gluino X -> t t (or tbar tbar) + h0 + 2jets + Etmiss + X. The QFV bosonic squark decays can have an influence on the squark and gluino searches at LHC., Figure 3 replaced, Section 4 revised

International audience

In this paper we propose to use the measurement of the thermal Quark-Gluon Plasma (QGP) dilepton spectra in the Intermediate Mass Region (IMR) of heavy-ion collisions, as a new method to search for GeV-scale dark gauge bosons (gamma' or Z'). Such light mediators are a common feature of light (i.e. low mass) dark matter scenarios, which have been invoked to explain puzzling signals in dark matter indirect and direct detection experiments. First we show that a light gamma' or Z' will generate a resonant enhancement of the dilepton spectrum produced thermally by the QGP, at an energy corresponding to the dark gauge boson mass. Secondly, using data from the PHENIX experiment, we are able to set an upper limit on the combined coupling of this new gauge boson to quarks and leptons (independently of their vectorial or axial nature) chi_q chi_e < 10^(-3) at the 95% confidence level for a gauge boson mass in the range 1.5 - 2.5 GeV. This result complements previous searches for new light gauge bosons and probes a new region of the parameter space, particularly interesting in the case of non-universal couplings to quarks and leptons. Prospects for the discovery of such a boson by the ALICE collaboration are also discussed., 11 pages, 4 figures