Ref HAL: in2p3-00121100_v1
Ref Arxiv: hep-ph/0504021
DOI: 10.1016/j.physletb.2006.12.025
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
25 citations
Résumé:

It is shown that gravitinos with mass m_{3/2} ~ 0.1-1 MeV may provide suitable cold dark matter candidates in scenarios of gauge mediated supersymmetry breaking (GMSB) under SO(10) grand unification coupled to supergravity, which accommodate a messenger sector of mass scale M_X ~ 10^6 GeV. This is due to the combined effects of renormalizable loop-suppressed operators and generic non-renormalizable ones governing the dilution of a pre-existing equilibrium gravitino abundance via messenger decay. The above range of gravitino and messenger masses can be accommodated in indirect GMSB scenarios. The gravitino abundance does not depend on the post-inflationary reheat temperature and it is shown that leptogenesis can generate successfully the baryon asymmetry.

Commentaires: 8 pages - version to appear in Phys.Lett.B ; discussion of one loop annihilation cross-section modified, conclusions unchanged

Ref HAL: in2p3-00025952_v1
Ref Arxiv: hep-ph/0506129
DOI: 10.1103/PhysRevD.73.043514
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
40 citations
Résumé:

This paper investigates the parameter space of theories with gauge mediated supersymmetry breaking leading to gravitino (cold) dark matter with mass m_{3/2}= 1keV - 10MeV. We pay particular attention to the cosmological role of messenger fields. Cosmology requires that these messengers decay to the visible sector if the lightest messenger mass M_X > 30TeV. We then examine the various possible messenger number violating interactions allowed by the symmetries of the theory and by phenomenology. Late messenger decay generally results in entropy production hence in the dilution of pre-existing gravitinos. We find that in SU(5) grand unification only specific messenger-matter couplings allow to produce the required amount of gravitino dark matter particles. Gravitino dark matter with the correct abundance is however expected in larger gauge groups such as SO(10) for generic non-renormalizable messenger-matter interactions and for arbritrarily high post-inflationary reheating temperatures.

Commentaires: 20 pages, double column revtex format, 5 figures

Commentaires: Proceedings of the IX International Conference on Particles, Strings and Cosmology (PASCOS 2003) - Part II Plenary Session

Ref HAL: hal-00259267_v1
Ref Arxiv: hep-ph/0406253
DOI: 10.1103/PhysRevD.70.071301
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
4 citations
Résumé:

We consider the production of neutralino, chargino, and charged Higgs boson pairs in the MSSM framework at future $e^+e^-$ colliders. We show that, for c.m. energies in the one TeV range and in a ``moderately'' light SUSY scenario, a combined analysis of the slopes of these production cross sections could lead to a strong consistency test involving the soft supersymmetric breaking parameters $M_1$, $M_2$, the Higgsino parameter $\mu$, and $\tan\beta$.

Commentaires: 5 pages, 3 figures, RevTeX 4; typos corrected in equations and figures

Ref Arxiv: hep-ph/0405036
Ref. & Cit.: NASA ADS
Résumé:

We consider the ratio of the cross section of production of heavy bottom-antibottom pairs ($sigma_{bbar b}$) to the cross section of production of top-antitop pairs ($sigma_{tbar t}$) at LHC. We show that in this ratio a major fraction of virtual contributions (including QCD components) disappears, leaving a residual dominant electroweak Yukawa effect that might be strongly enhanced in the presence of supersymmetry. A quantitative numerical analysis of the size of the effect is also performed under the assumption of a relatively light supersymmetric scenario.

Commentaires: Publication reprise avec PM/04-53.

Ref HAL: hal-00259266_v1
Ref Arxiv: hep-ph/0403099
DOI: 10.1103/PhysRevD.69.091301
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
8 citations
Résumé:

We consider the production of chargino and charged Higgs boson pairs at future linear colliders for c.m. energies in the one TeV range. Working in the MSSM under the assumption of a "moderately" light SUSY scenario, we compute the leading (double) and next-to leading (linear) supersymmetric logarithmic terms of the so-called "Sudakov expansion" at one loop. We show that a combined analysis of the slopes of the chargino and of the charged Higgs production cross sections would offer a simple possibility for determining $\tan\beta$ for large ($\gtrsim 10$) values and an allowed strip in the ($M_2,\mu$) plane. This could provide a strong consistency test of the considered supersymmetric model.

Commentaires: 4 pages, 4 Encapsulated PostScript Figures

Ref Arxiv: hep-ph/0404162
DOI: 10.1103/PhysRevD.70.033011
Ref. & Cit.: NASA ADS
11 citations
Résumé:

We consider the production of neutralino pairs $tchi^0_itchi^0_j$ at a high energy hadron collider, putting a special emphasis on the case where one of them is the lightest neutralino $tchi^0_1$, possibly constituting the main Dark Matter component. At tree level, the only relevant subprocess is $qbar qto tchi^0_itchi^0_j$, while the subprocess $ggto tchi^0_itchi^0_j$ first appears at the one loop level. Explicit expressions for the $qbar q$-helicity amplitudes are presented, including the tree level contributions and the leading-log one loop radiative corrections. For the one-loop $ ggto tchi^0_itchi^0_j$ process, a numerical code named PLATONggnn is released, allowing the computation of $dsigma /d that$ in any MSSM model with real soft breaking parameters. It turns out that acceptable MSSM benchmark models exist for which the $qbar q $ and the gluonic contributions may give comparable effects at LHC, due to the enhanced gluonic structure functions at low fractional momenta. Depending on the values of the MSSM parameters, we find that the LHC neutralino pair production may provide sensitive tests of SUSY models generating neutralino Dark Matter.