Relic density calculations beyond tree-level, exact calculations versus effective couplings: the ZZ final state

The inferred value of the relic density from cosmological observations has reached a precision that is akin to that of the LEP precision measurements. This level of precision calls for the evaluation of the annihilation cross sections of dark matter that goes beyond tree-level calculations as currently implemented in all codes for the computation of the relic density. In supersymmetry radiative corrections are known to be large and thus must be implemented. Full one-loop radiative corrections for many annihilation processes have been performed. It is important to investigate whether the bulk of these corrections can be parameterised through an improved Born approximation that can be implemented as a selection of form factors to a tree-level code. This paper is a second in a series that addresses this issue. After having provided these form factors for the annihilation of the neutralinos into fermions, which cover the case of a bino-like LSP (Lightest Supersymmetric Particle), we turn our attention here to a higgsino-like dark matter candidate through its annihilation into $ZZ$. We also investigate the cases of a mixed LSP. In all cases we compare the performance of the form factor approach with the result of a full one-loop correction. We also study the issue of the renormalisation scheme dependence. An illustration of the phenomenon of non decoupling of the heavy sfermions that takes place for the annihilation of the lightest neutralino into $ZZ$ is also presented.Comment: 20

SUSY Higgs searches : beyond the MSSM

The recent results from the ATLAS and CMS collaborations show that the allowed range for a Standard Model Higgs boson is now restricted to a very thin region. Although those limits are presented exclusively in the framework of the SM, the searches themselves remain sensitive to other Higgs models. We recast the limits within a generic supersymmetric framework that goes beyond the usual minimal extension. Such a generic model can be parameterised through a supersymmetric effective Lagrangian with higher order operators appearing in the K\"ahler potential and the superpotential, an approach whose first motivation is to alleviate the fine-tuning problem in supersymmetry with the most dramatic consequence being a substantial increase in the mass of the lightest Higgs boson as compared to the minimal supersymmetic model. We investigate in this paper the constraints set by the LHC on such models. We also investigate how the present picture will change when gathering more luminosity. Issues of how to combine and exploit data from the LHC dedicated to searches for the standard model Higgs to such supersymmetry inspired scenarios are discussed. We also discuss the impact of invisible decays of the Higgs in such scenarios.Comment: - Mathematics typos corrected. - Added a small section to take into account the latest update from ATLAS and CMS with 5fb-1. - Small changes to the text especially the conclusions in view of the latest data from the LHC. - Updated bibliograph

One-loop corrections, uncertainties and approximations in neutralino annihilations: Examples

The extracted value of the relic density has reached the few per-cent level precision. One can therefore no longer content oneself with calculations of this observable where the annihilation processes are computed at tree-level, especially in supersymmetry where radiative corrections are usually large. Implementing full one-loop corrections to all annihilation processes that would be needed in a scan over parameters is a daunting task. On the other hand one may ask whether the bulk of the corrections are taken into account through effective couplings of the neutralino that improve the tree-level calculation and would be easy to implement. We address this issue by concentrating in this first study on the neutralino coupling to i) fermions and sfermions and ii) Z. After constructing the effective couplings we compare their efficiency compared to the full one-loop calculation and comment on the failures and success of the approach. As a bonus we point out that large non decoupling effects of heavy sfermions could in principle be measured in the annihilation process, a point of interest in view of the latest limit on the squark masses from the LHC. We also comment on the scheme dependencies of the one-loop corrected results

On the presentation of the LHC Higgs Results

We put forth conclusions and suggestions regarding the presentation of the LHC Higgs results that may help to maximize their impact and their utility to the whole High Energy Physics community.Comment: Conclusions from the workshops "Likelihoods for the LHC Searches", 21-23 January 2013 at CERN, "Implications of the 125 GeV Higgs Boson", 18-22 March 2013 at LPSC Grenoble, and from the 2013 Les Houches "Physics at TeV Colliders" workshop. 16 pages, 3 figures. Version 2: Comment added on the first publication of signal strength likelihoods in digital form by ATLA

Les Houches 2011: Physics at TeV Colliders New Physics Working Group Report

We present the activities of the "New Physics" working group for the "Physics at TeV Colliders" workshop (Les Houches, France, 30 May-17 June, 2011). Our report includes new agreements on formats for interfaces between computational tools, new tool developments, important signatures for searches at the LHC, recommendations for presentation of LHC search results, as well as additional phenomenological studies.Comment: 243 pages, report of the Les Houches 2011 New Physics Group; fix three figure

Supersymmetric Higgses beyond the MSSM: An update with avour and Dark Matter constraints

International audienceSpurred by the discovery of a boson resonance at the LHC as the result of thesearch for the Standard Model Higgs, we pursue our investigation of theproperties and signatures of Higgses in an effective supersymmetric scenariothat goes beyond the usual MSSM. Such scenarios were first introduced toalleviate the naturalness problem of the MSSM Higgs and are found to have avery rich phenomenology that allows departures from the Standard Model in theproduction rate of the Higgs in many of the search channels. We now include theconstraints from flavour observables in particular the rare decays b-> s gammaand Bs -> mu+ mu- including the recent measurement from LHCb. We also addressthe issue of Dark Matter and its impact on Higgs physics. In particular, weincorporate the latest data from XENON100 on the spin independent directdetection rates. These turn out to be powerful constraints, especially if onealso imposes that the observed thermal relic density is obtained. We also studymodels with a low abundance that can more easily evade the direct detectionrates. We study the impact of the flavour and Dark Matter observables on theproduction rates of the Higgs at the LHC, and their correlations in thediphoton, diphoton+jets and 4 leptons. We also comment on the other channels

Beyond the MSSM Higgses at 125 GeV

International audienceThe BMSSM framework is an effective theory approach that encapsulates avariety of extensions beyond the MSSM with which it shares the same fieldcontent. The lightest Higgs mass can be much heavier than in the MSSM withoutcreating a tension with naturalness or requiring superheavy stops. Thephenomenology of the Higgs sector is at the same time much richer. Wecritically review the properties of a Higgs with mass around 125GeV in thismodel. In particular, we investigate how the rates in the important inclusive 2photons channel, the 2 photons + 2 jets and the ZZ to 4 leptons (and/or WW) canbe enhanced or reduced compared to the standard model and what kind ofcorrelations between these rates are possible. We consider both a vanilla modelwhere stops have moderate masses and do not mix and a model with large mixingand a light stop. We show that in both cases there are scenarios that lead toenhancements in these rates at a mass of 125GeV corresponding either to thelightest Higgs or the heaviest CP-even Higgs of the model. In all of thesescenarios we study the prospects of finding other signatures either of the125GeV Higgs or those of the heavier Higgses. In most cases the \oo{\tau}\tauchannels are the most promising. Exclusion limits from the recent LHC Higgssearches are folded in our analyses while the tantalising hints for a Higgssignal at 125GeV are used as an example of how to constrain the BMSSM and/ordirect future searches