Revisiting light neutralino scenarios in the MSSM

We revisit the case of a light neutralino LSP in the framework of the MSSM. We consider a model with eleven free parameters. We show that all scenarios where the annihilation of light neutralinos rely mainly on the exchange of a light pseudoscalar are excluded by direct detection searches and by Fermi measurements of the gamma-flux from dwarf spheroidal galaxies. On the other hand, we find scenarios with light sleptons that satisfy all collider and astroparticle physics constraints. In this case, the lower limit on the LSP mass is 12.6 GeV. We discuss how the parameter space of the model will be further probed by new physics searches at the LHC.Comment: 7 pages, 8 figure

Corps de femmes et couleurs de peau :

À Santiago deux femmes s’affrontent. La procédure du délit d’injures nécessite, dans cette société orale de la première moitié du xviiie siècle, l’exposé de questions sensibles qui concernent, dans ce cas particulier, les identités féminines. Croisées par de multiples variables, dont l’ethnie est l’une des plus importantes, ces identités de femmes s’expriment dans des lieux sociaux plus ou moins contestés : la fragilité de ces identités s’observe dans l’expression de la violence privée et dans les discours juridiques. Réfléchir sur la manière d’appréhender et de vivre les possibilités d’être femme dans une des villes de l’Amérique hispanique est un des objectifs de cette analyse. L’autre, montre comment les discours sur le métissage et les valeurs qu’ils portent s’incarnent dans les sujets au niveau des conflits mineurs, quotidiens, jusqu’à faire basculer, à travers la parole et l’opinion sur autrui, des parcours individuels.Verbal confrontations between women in early 18th century Santiago brought women into the courtroom where juridical procedures concerning slander raised issues about feminine identity. A variety of factors shaped these identities, including most notably ethnicity. In contested social locations, women were often the object of interpersonal violence and juridical discourse. This article considers the varieties of women’s experiences and how these shaped their identities in a Spanish American city of the period. It also examines the discourses about miscegenation and how they became embodied on the subjects engaged in acts of minor daily conflicts ; the words and judgments of others at times had dramatic consequences on individual lives

Loop-induced photon spectral lines from neutralino annihilation in the NMSSM

We have computed the loop-induced processes of neutralino annihilation into two photons and, for the first time, into a photon and a Z boson in the framework of the NMSSM. The photons produced from these radiative modes are monochromatic and possess a clear "smoking gun" experimental signature. This numerical analysis has been done with the help of the SloopS code, initially developed for automatic one-loop calculation in the MSSM. We have computed the rates for different benchmark points coming from SUGRA and GMSB soft SUSY breaking scenarios and compared them with the MSSM. We comment on how this signal can be enhanced, with respect to the MSSM, especially in the low mass region of the neutralino. We also discuss the possibility of this observable to constrain the NMSSM parameter space, taking into account the latest limits from the FERMI collaboration on these two modes.Comment: 18 pages, 3 figures. Minor clarifications added in the text. Typing mistakes and references corrected. Matches published versio

Light neutralino dark matter in the MSSM and its implication for LHC searches for staus

It was shown in a previous study that a lightest neutralino with mass below 30 GeV was severely constrained in the minimal supersymmetric standard model (MSSM), unless it annihilates via a light stau and thus yields the observed dark matter abundance. In such a scenario, while the stau is the next-to-lightest supersymmetric particle (NLSP), the charginos and the other neutralinos as well as sleptons of the first two families are also likely to be not too far above the mass bounds laid down by the Large Electron Positron (LEP) collider. As the branching ratios of decays of the charginos and the next-to-lightest neutralino into staus are rather large, one expects significant rates of tau-rich final states in such a case. With this in view, we investigate the same-sign ditau and tri-tau signals of this scenario at the Large Hadron Collider (LHC) for two MSSM benchmark points corresponding to light neutralino dark matter. The associated signal rates for these channels are computed, for the centre-of-mass energy of 14 TeV. We find that both channels lead to appreciable rates if the squarks and the gluino are not too far above a TeV, thus allowing to probe scenarios with light neutralinos in the 14 TeV LHC run with 10-100 fb^{-1}.Comment: 19p, 4 Fig

Directional detection of Dark Matter

Directional detection is a promising Dark Matter search strategy. Taking advantage on the rotation of the Solar system around the galactic center through the Dark Matter halo, it allows to show a direction dependence of WIMP events. It requires the simultaneous measurement of the energy and the 3D track of low energy recoils, which is a common challenge for all current projects of directional detectors. The third CYGNUS workshop on directional dark matter detection has brought together the scientific community working on both theoretical and experimental aspects of the subject. In this paper, we give an introductory revue of directional detection of Dark Matter, focusing on the main recent progresses.Comment: Proceedings of the 3rd International conference on Directional Detection of Dark Matter (CYGNUS 2011), Aussois, France, 8-10 June 201

The Higgs sector of the phenomenological MSSM in the light of the Higgs boson discovery

The long awaited discovery of a new light scalar at the LHC opens up a new era of studies of the Higgs sector in the SM and its extensions. In this paper we discuss the consequences of the observation of a light Higgs boson with the mass and rates reported by the ATLAS and CMS collaborations on the parameter space of the phenomenological MSSM, including also the so far unsuccessful LHC searches for the heavier Higgs bosons and supersymmetric particle partners in missing transverse momentum as well as the constraints from B physics and dark matter. We explore the various regimes of the MSSM Higgs sector depending on the parameters MA and tan beta and show that only two of them are still allowed by all present experimental constraints: the decoupling regime where there is only one light and standard--like Higgs boson and the supersymmetric regime in which there are light supersymmetric particle partners affecting the decay properties of the Higgs boson, in particular its di-photon and invisible decays.Comment: 21 pages, 9 figures v2 - Discussion of the impact of LHC data extended, scan statistics increased, a few figures added and typos correcte

Dark Matter in 3D

We discuss the relevance of directional detection experiments in the post-discovery era and propose a method to extract the local dark matter phase space distribution from directional data. The first feature of this method is a parameterization of the dark matter distribution function in terms of integrals of motion, which can be analytically extended to infer properties of the global distribution if certain equilibrium conditions hold. The second feature of our method is a decomposition of the distribution function in moments of a model independent basis, with minimal reliance on the ansatz for its functional form. We illustrate our method using the Via Lactea II N-body simulation as well as an analytical model for the dark matter halo. We conclude that O(1000) events are necessary to measure deviations from the Standard Halo Model and constrain or measure the presence of anisotropies.Comment: 36 pages, 13 figure

Dark Matter and Higgs Mass in the CMSSM with Yukawa Quasi-Unification

We present an updated analysis of the constrained minimal supersymmetric standard model with mu>0 supplemented by an `asymptotic' Yukawa coupling quasi-unification condition, which allows an acceptable b-quark mass. Imposing constraints from the cold dark matter abundance in the universe, B physics, the muon anomalous magnetic moment, and the mass m_h of the lightest neutral CP-even Higgs boson, we find that the lightest neutralino cannot act as a cold dark matter candidate. This is mainly because the upper bound on the lightest neutralino relic abundance from cold dark matter considerations, despite the fact that this abundance is drastically reduced by neutralino-stau coannihilations, is incompatible with the recent data on the branching ratio of B_s --> mu^+ mu^-. Allowing for a different particle, such as the axino or the gravitino, to be the lightest supersymmetric particle and, thus, constitute the cold dark matter in the universe, we find that the predicted m_h's in our model favor the range (119-126) GeV.Comment: 13 pages including 4 figures and 1 table, talk given by G. Lazarides at the 7th International Workshop on the Dark Side of the Universe, KITPC, Beijing, China, September 26-30, 2011 (to appear in the proceedings