Ref HAL: hal-00281347_v1
Ref Arxiv: 0710.5153
DOI: 10.1088/1475-7516/2008/03/008
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57 citations
Résumé:

The Big Bang nucleosynthesis (BBN) process in the presence of charged massive particles (CHAMPs) is studied in detail. All currently known effects due to the existence of bound states between CHAMPs and nuclei, including possible late-time destruction of 6Li and 7Li, are included. The study sets conservative bounds on CHAMP abundances in the decay time range 3\times 10^2~\mathrm {s}\lesssim \tau_x\lesssim 10^{12}~\mathrm {s} . It is stressed that the production of 6Li at early times T~10 keV is overestimated by a factor ~10 when the approximation of the Saha equation for the 4He bound state fraction is utilized. To obtain conservative limits on the abundance of CHAMPs, a Monte Carlo analysis with ~3 × 106 independent BBN runs, varying the reaction rates of 19 different reactions, is performed. The analysis yields the surprising result that, except for small areas in the particle parameter space, conservative constraints on the abundance of decaying charged particles are currently very close to those of neutral particles. It is shown that, in the case that the rates of a number of heretofore unconsidered reactions may be determined reliably in the future, it is conceivable that the limit on CHAMPs in the early Universe could be tightened by orders of magnitude.

Ref HAL: in2p3-00136826_v1
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Ref HAL: hal-00258621_v1
Ref Arxiv: 0801.0045
DOI: 10.1016/j.cpc.2008.08.004
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263 citations
Résumé:

The Supersymmetry Les Houches Accord (SLHA) provides a universal set of conventions for conveying spectral and decay information for supersymmetry analysis problems in high energy physics. Here, we propose extensions of the conventions of the first SLHA to include various generalisations: the minimal supersymmetric standard model with violation of CP, R-parity, and flavour, as well as the simplest next-to-minimal model.

Commentaires: 35 pages

Ref HAL: hal-00264735_v1
Ref Arxiv: 0803.0813
DOI: 10.1103/PhysRevD.77.093007
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8 citations
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We analyze the quark-gluon induced process $u g\to \tilde d\tchi_i^+$, including the one loop electroweak (EW) effects in the minimal supersymmetric model (MSSM). This process is determined by four helicity amplitudes, three of which are violating helicity conservation, and another one which respects it and is logarithmically enhanced at high energy. Combining this $u g\to \tilde d\tchi_i^+$ analysis with a corresponding one for $u g \to d W^+$, we obtain simple approximate relations between the two processes, testing the MSSM structure at the amplitude and the cross section levels. These relations become exact at asymptotic energies and, provided the SUSY scale is not too heavy, they may be approximately correct at LHC energies also. In addition to these, we study the 1loop EW corrections to the inclusive $\tilde d\tchi_i^+$ production at LHC, presenting as examples, the $p_T$ and angular distributions. Comparing these to the corresponding predictions for $W$+jet production derived earlier, provides an accurate test of the supersymmetric assignments.

Ref HAL: hal-00280728_v1
Ref Arxiv: 0802.1994
DOI: 10.1103/PhysRevD.77.113018
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23 citations
Résumé:

We have computed the complete one-loop electroweak effects in the MSSM for single top (and single antitop) production in the t-channel at hadron colliders, generalizing a previous analysis performed for the dominant dt final state and fylly including QED effects. The results are quite similar for all processes. The overall Standard Model one-loop effect is small, of the few percent size. This is due to a compenstion of weak and QED contributions that are of opposite sign. The genuine SUSY contribution is generally quite modest in the mSUGRA scenario. The experimental observables would therefore only practically depend, in this framework, on the CKM Wtb coupling.

Commentaires: 10 pages

Ref HAL: in2p3-00204175_v1
Ref Arxiv: 0801.1800
DOI: 10.1140/epjc/s10052-008-0713-4
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57 citations
Résumé:

This review presents flavour related issues in the production and decays of heavy states at LHC, both from the experimental side and from the theoretical side. We review top quark physics and discuss flavour aspects of several extensions of the Standard Model, such as supersymmetry, little Higgs model or models with extra dimensions. This includes discovery aspects as well as measurement of several properties of these heavy states. We also present public available computational tools related to this topic.

Commentaires: Report of Working Group 1 of the CERN Workshop ``Flavour in the era of the LHC'', Geneva, Switzerland, November 2005 -- March 2007

Ref HAL: hal-00377723_v1
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Commentaires: Also in Nucl. Phys. B, Proc. Suppl. 174 (2007)