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F. Boudjema

Publications and source records attributed to F. Boudjema.

At least 19 recordsLinked to original sources
arXiv2026

micrOMEGAs 7: Beyond standard cosmology

We present micrOMEGAs7, a major upgrade of the micrOMEGAs package for the computation of dark matter observables in generic models. This release introduces a generalized treatment of the Boltzmann equations, allowing for user-defined modifications of the Hubble expansion rate, entropy evolution, and non-thermal dark matter production from late-decaying cosmological components, thereby extending the framework beyond the standard radiation-dominated cosmology. The relic density can now be computed in scenarios such as low-temperature reheating, early matter domination, and kination. The new version also improves the treatment of sub-GeV dark matter, in particular annihilation into light mesons through scalar mediators, and provides updated spectra for indirect detection. Several experimental and observational constraints have been implemented or revised, including CMB bounds from Planck on energy injection during recombination and Fermi-LAT limits from dwarf spheroidal galaxies. For direct detection, a recast of recent LZ results has been included, and the code now takes into account effective electromagnetic couplings of spin-$1/2$ and spin-1 dark matter. Collider observables have also been extended through the implementation of CMS dilepton resonance constraints on $Z'$ mediators. Additional improvements include a more flexible treatment of effective relativistic degrees of freedom and an updated LHAPDF interface.

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arXiv2023

micrOMEGAs 6.0: N-component dark matter

micrOMEGAs is a numerical code to compute dark matter (DM) observables in generic extensions of the Standard Model of particle physics. We present a new version of micrOMEGAs that includes a generalization of the Boltzmann equations governing the DM cosmic abundance evolution which can be solved to compute the relic density of N-component DM. The direct and indirect detection rates in such scenarios take into account the relative contribution of each component such that constraints on the combined signal of all DM components can be imposed. The co-scattering mechanism for DM production is also included, whereas the routines used to compute the relic density of feebly interacting particles have been improved in order to take into account the effect of thermal masses of t-channel particles. Finally, the tables for the DM self-annihilation - induced photon spectra have been extended down to DM masses of 110 MeV, and they now include annihilation channels into light mesons.

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arXiv2017

Collider limits on new physics within micrOMEGAs4.3

Results from the LHC put severe constraints on models of new physics. This includes constraints on the Higgs sector from the precise measurement of the mass and couplings of the 125GeV Higgs boson, as well as limits from searches for other new particles. We present the procedure to use these constraints in micrOMEGAs by interfacing it to the external codes Lilith, HiggsSignals, HiggsBounds and SModelS. A few dedicated modules are also provided. With these new features, micrOMEGAs_4.3 provides a generic framework for evaluating dark matter observables together with collider and non-collider constraints.

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arXiv2017

One-loop renormalisation of the NMSSM in SloopS 2: the Higgs sector

We present a full one-loop renormalisation of the Higgs sector of the Next-to-Minimal- Supersymmetric-Standard-Model (NMSSM) and its implementation within SloopS, a code for the automated computations of one-loop processes in theories beyond the Stan- dard Model. The present work is the sequel to the study we performed on the renor- malisation of the sectors of the NMSSM comprising neutralinos, charginos and sfermions thereby completing the full one-loop renormalisation of the NMSSM. We have investi- gated several renormalisation schemes based on alternative choices (on-shell or DR) of the physical parameters. Special attention is paid to the issue of the mixing between physical fields. To weigh the impact of the different renormalisation schemes, the partial widths for the decays of the Higgs bosons into supersymmetric particles are computed at one-loop. In many decays large differences between the schemes are found. We discuss the origin of these differences. In particular we study two contrasting scenarios. The first model is MSSM-like with a small value for the mixing between the doublet and sin- glet Higgs superfields while the second model has a moderate value for this mixing. We critically discuss the issue of the reconstruction of the underlying parameters and their counterterms in the case of a theory with a large number of parameters, such as the NMSSM, from a set of physical parameters. In the present study this set corresponds to the minimum set of masses for the implementation of the on-shell schemes.

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arXiv2016

One-loop renormalisation of the NMSSM in SloopS : 1. the neutralino-chargino and sfermion sectors

We have completed the one-loop renormalisation of the Next-to-Minimal Supersymmetric Standard Model (NMSSM) allowing for and comparing between different renormalisation schemes. A special attention is paid to on-shell schemes. We study a variety of these schemes based on alternative choices of the physical input parameters. In this paper we present our approach to the renormalisation of the NMSSM and report on our results for the neutralino-chargino and sfermion sectors. We will borrow some results from our study of the Higgs sector whose full discussion is left for a separate publication. We have implemented the set up for all the sectors of the NMSSM within \sloops, a code for the automatic computation of one-loop corrections initially developed for the standard model and the MSSM. Among the many applications that allows the code, we present here the one-loop corrections to neutralino masses and to partial widths of neutralinos and charginos into final states with one gauge boson. One-loop electroweak and QCD corrections to the partial widths of third generation sfermions into a fermion and a chargino or a neutralino are also computed.

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arXiv2014

micrOMEGAs4.1: two dark matter candidates

micrOMEGAs is a code to compute dark matter observables in generic extensions of the standard model. This version of micrOMEGAs includes a generalization of the Boltzmann equations to take into account the possibility of two dark matter candidates. The modification of the relic density calculation to include interactions between the two DM sectors as well as semi-annihilation is presented. Both DM signals in direct and indirect detection are computed as well. An extension of the standard model with two scalar doublets and a singlet is used as an example.

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arXiv2014

Les Houches 2013: 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, 3--21 June, 2013). Our report includes new computational tool developments, studies of the implications of the Higgs boson discovery on new physics, important signatures for searches for natural new physics at the LHC, new studies of flavour aspects of new physics, and assessments of the interplay between direct dark matter searches and the LHC.

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arXiv2014

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.

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arXiv2013

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.

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arXiv2013

micrOMEGAs3.1 : a program for calculating dark matter observables

micrOMEGAs is a code to compute dark matter observables in generic extensions of the standard model. This new version of micrOMEGAs is a major update which includes a generalization of the Boltzmann equations to accommodate models with asymmetric dark matter or with semi-annihilation and a first approach to a generalization of the thermodynamics of the Universe in the relic density computation. Furthermore a switch to include virtual vector bosons in the final states in the annihilation cross sections or relic density computations is added. Effective operators to describe loop-induced couplings of Higgses to two-photons or two-gluons are introduced and reduced couplings of the Higgs are provided allowing for a direct comparison with recent LHC results. A module that computes the signature of DM captured in celestial bodies in neutrino telescopes is also provided. Moreover the direct detection module has been improved as concerns the implementation of the strange "content" of the nucleon. New extensions of the standard model are included in the distribution.

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arXiv2012

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

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

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arXiv2012

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.

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arXiv2012

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 Kähler 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.

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arXiv2010

Indirect search for dark matter with micrOMEGAs2.4

We present a new module of micrOMEGAs devoted to the computation of indirect signals from dark matter annihilation in any new model with a stable weakly interacting particle. The code provides the mass spectrum, cross-sections, relic density and exotic fluxes of gamma rays, positrons and antiprotons. The propagation of charged particles in the Galactic halo is handled with a new module that allows to easily modify the propagation parameters.

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arXiv2010

micrOMEGAs : a tool for dark matter studies

micrOMEGAs is a tool for cold dark matter (DM) studies in generic extensions of the standard model with a R-parity like discrete symmetry that guarantees the stability of the lightest odd particle. The code computes the DM relic density, the elastic scattering cross sections of DM on nuclei relevant for direct detection, and the spectra of positrons, anti-protons and photons originating from DM annihilation including porpagation of charged cosmic rays. The cross sections and decay properties of new particles relevant for collider studies are included as well as constraints from the flavour sector on the parameter space of supersymmetric models.

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