Ref HAL: hal-00259271_v1
Ref Arxiv: hep-ph/0309032
DOI: 10.1103/PhysRevD.69.075007
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
11 citations
Résumé:

The complete 1-loop computation of the processes $(\tchi^0_i \tchi^0_j \leftrightarrow\gamma\gamma, ~ gg)$, for any pair of the four MSSM neutralinos, has been performed for an arbitrary c.m energy. As a first application suitable for Dark Matter (DM) searches, the neutralino-neutralino annihilation is studied at relative velocities $v/c\simeq 10^{-3}$ describing the present DM distribution in the galactic halo, and $v/c\simeq 0.5$ determining neutralino relic density contributions. Numerical results are presented for 31 MSSM benchmark models indicating considerable sensitivity to the input parameters. Numerical codes are released, which may be used for the computation of the annihilation of any two neutralinos to two photons or two gluons at the aforementioned $v/c$ values. In the near future, we intend to complement them with codes for the inverse process $\gamma\gamma \to \tchi^0_i \tchi^0_j$, observable at the future high energy Linear Colliders.

Commentaires: 14 pages and 1 figure

Ref Arxiv: hep-ph/0304175
DOI: 10.1016/S0550-3213(03)00413-9
Ref. & Cit.: NASA ADS
24 citations
Résumé:

We compare the logarithmic Sudakov expansions of the process e+e- --> W+W- in the one-loop approximation and in the resummed version, to subleading order accuracy, in the SM case and in a light SUSY scenario for the MSSM. We show that the two expansions are essentially identical below 1 TeV, but differ drastically at higher (2,3 TeV) center of mass energies. Starting from these conclusions, we argue that a complete one-loop calculation in the energy region below 1 TeV does not seem to need extra two-loop corrections, in spite of the relatively large size of the one-loop effects.

Ref Arxiv: hep-ph/0303004
DOI: 10.1016/j.physletb.2003.06.058
Ref. & Cit.: NASA ADS
19 citations
Résumé:

We evaluate systematically some new contributions of the QCD scalar mesons, including radiative decay-productions, not considered with a better attention until now in the evaluation of the hadronic contributions to the muon anomaly. The sum of the scalar contributions to be added to the existing Standard Model predictions a_mu^{SM} are estimated in units 10^{-10} to be a^{S}_mu= 1.0(0.6) [TH based]} and 13(11) [ PDG based], where the errors are dominated by the ones from the experimental widths of these scalar mesons. PDG based results suggest that the value of a_mu^{SM} and its errors might have been underestimated in previous works. The inclusion of these new effects leads to a perfect agreement (< 1.1\sigma) of the measured value a^{exp}_mu and a_mu^{SM} from tau-decay and implies a (1.5 ~ 3.3) sigma discrepancy between a^{exp}_mu and a_mu^{SM} from e^+e^- into hadrons data. More refined unbiased estimates of a_mu^{SM} require improved measurements of the scalar meson masses and widths. The impact of our results to a_mu^{SM} is summarized in the conclusions.

Ref HAL: hal-00369189_v1
Ref Arxiv: hep-ph/0304110
DOI: 10.1142/S0217751X03015702
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
43 citations
Résumé:

We consider the high energy behaviour of the amplitudes for pair production of charged leptons, quarks, Higgs bosons, sleptons, squarks and charginos at lepton colliders. We give the general expressions of the leading quadratic and subleading linear logarithms that appear at the one loop level, and derive the corresponding resummed expansions to underlinesubleading logarithmic order accuracy. Under the assumption of a relatively light SUSY scenario and choosing the MSSM as a specific model, we compare the predictions of the one-loop and of the resummed expansions at variable energy. We show that the two predictions are very close in the one TeV regime, but drastically differ in the few (2,3) TeV range.

Commentaires: Partially supported by EU contract HPRN-CT-2000-00149.

Ref Arxiv: physics/0212085
Ref. & Cit.: NASA ADS
Résumé:

In the first part of this report, I discuss the sociological role of fundamental research in Developing Countries (DC) and how to realize this program. In the second part, I give a brief and elementary introduction to the field of high-energy physics (HEP), accessible to a large audience not necessary physicists. The aim of this report is to make piliticians and financial bakers aware oon the long-term usefulness of fundamental research in DC and on the possible globalisation of HEP and, in general, of science.

Commentaires: English version of the communications in French at the press: Tribune de Madagascar (# 4212, 26 nov.2002)

Ref HAL: hal-00259272_v1
Ref Arxiv: hep-ph/0212167
DOI: 10.1103/PhysRevD.68.035014
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
18 citations
Résumé:

We consider the production, at future lepton colliders, of charged Higgs pairs in supersymmetric models. Assuming a relatively light SUSY scenario, and working in the MSSM, we show that, for c.m. energies in the one TeV range, a one-loop logarithmic Sudakov expansion that includes an "effective" next-to subleading order term is adequate to the expected level of experimental accuracy. We consider then the coefficient of the linear (subleading) SUSY Sudakov logarithm and the SUSY next to subleading term of the expansion and show that their dependence on the supersymmetric parameters of the model is drastically different. In particular the coefficient of the SUSY logarithm is only dependent on $\tan\beta$ while the next to subleading term depends on a larger set of SUSY parameters. This would allow to extract from the data separate informations and tests of the model.

Commentaires: 18 pages and 13 figures

DOI: 10.1007/10857580_45
Résumé:

Considering a NFW halo of M 31 made of neutralinos, predictions for the \x{03B3} fluxes are computed for different sets of SUSY parameters using the DarkSuspect MC simulation [1] [2]. Then they are compared with the efficiency of CELESTE Cerenkov telescope [3] which has a threshold energy of 30 GeV.

Commentaires: Astronomy, Cosmology and Fundamental Physics: