Ref Arxiv: hep-ph/0112273
DOI: 10.1103/PhysRevD.65.093007
Ref. & Cit.: NASA ADS
25 citations
Résumé:

We consider the production of supersymmetric (SUSY) scalar pairs at lepton colliders, for c.m. energies much larger than the mass of the heaviest SUSY (real or virtual) particle involved in the process. In that energy regime, we derive the leading and subleading terms of the electroweak Sudakov logarithms in the MSSM, first working at one loop with physical states and then resumming to all orders with asymptotic expansions. We show that the first order of the resummed expression reproduces the physical one loop approximation, and compute systematically the possible effects on various observables both at one loop and to all orders. We discuss the regimes and the observables where the one loop approximation can or cannot be trusted, working in an energy range between 1 TeV and 4 TeV under a “light” SUSY mass assumption. As a by-product of our analysis, we propose a determination of the MSSM parameter tan β showing how a relative accuracy ≃25% can be easily achieved in the region tan β≳14, under reasonable experimental assumptions.

Ref Arxiv: astro-ph/0202336
DOI: 10.1016/S0032-0633(02)00089-2
Ref. & Cit.: NASA ADS
7 citations
Résumé:

It is widely believed that the cosmic baryon density may be obtained by inferring deuterium abundances in low-metallicity quasar absorption line systems. The implicit assumptions which enter this argument are critically assessed. In particular, the production of deuterium in non-standard Big Bang nucleosynthesis scenarios, the putative production of deuterium in astrophysical environments, and the possible destruction of deuterium via non-standard chemical evolution are discussed.

Commentaires: Article based on a talk presented at "Deuterium in the Universe", Meudon, June 2001

Ref Arxiv: astro-ph/0112226
DOI: 10.1088/0264-9381/19/13/303
Ref. & Cit.: NASA ADS
5 citations
Résumé:

This article gives a brief qualitative description of the possible evolution of the early Universe between the end of an inflationary epoch and the end of Big Bang nucleosynthesis. After a general introduction, establishing the minimum requirements cosmologists impose on this cosmic evolutionary phase, namely, successful baryogenesis, the production of cosmic dark matter, and successful light-element nucleosynthesis, a more detailed discussion on some recent developments follows. This latter includes the physics of preheating, the putative production of (alternative) dark matter, and the current status of Big Bang nucleosynthesis.

Commentaires: Article based on a talk presented at ``The Early Universe and Cosmological Observations: a Critical Review'', Cape Town, July 2001

Ref Arxiv: hep-ph/0203171
Ref. & Cit.: NASA ADS
Résumé:

In this talk, I present new results [1] obtained from QCD spectral sum rules(QSSR), on the bag constant parameters entering in the analysis of theB^0_{(s)}-\bar B^0_{(s)} mass-differences. Taking the average of the resultsfrom the Laplace and moment sum rules, one obtains to order \alpha_s:f_B\sqrt{\hat B_B}= (228 +- 61) MeV, f_{B_s}\sqrt{B_{B_s}}/{f_{B}\sqrt{B_{B}}=1.18 +- 0.03, in units where f_\pi=130.7 MeV. Combined with the experimentaldata on the mass-differences \Delta M_{d,s}, one obtains the constraint on theCKM weak mixing angle: |V_{ts}/V_{td}|^2 > 20.2(1.3). Alternatively, using theweak mixing angle from the analysis of the unitarity triangle and the data on\Delta M_d, one predicts \Delta M_s=18.3(2.1) ps^{-1} in agreement with thepresent experimental lower bound and within the reach of Tevatron 2.

Commentaires: Latex 2e, 4 pages. Talk presented at the 1st High-Energy Physics Madagascar International Conference Series (HEP-MAD'01), 27th sept-5th Oct. 2001, Antananarivo (to appear in World Scientific Proceedings)

Résumé:

summarize our self-contained determinations of the lowest order hadronic contributions to the anomalous magnetic moments a_{\mu,\tau} of the muon and tau leptons, the running QED coupling \alpha(M_Z) and the muonium hyperfine splitting \nu. Using as a revised estimate of the light-by light scattering: a_\mu(LL)=85(18) 10^{-11}, we deduce: a_\mu^{SM} = 116 591 861(78) 10^{-11}, a_\tau^{SM} = 117 759(7) 10^{-8}, giving: a_\mu^{SM}-a_\mu^{exp}=162(170) 10^{-11}. We also obtain: \alpha^{-1}(M_Z)=128.926(25) and the Fermi energy splitting: \nu_F^{SM}=4 459 031 783(229) {Hz}. Lower bounds on some eventual new physics are given, while \nu_F^{SM} leads e.g. to m_\mu/m_e=206.768 276(11) in remarkable agreement with the data.

Commentaires: Talk presented at the 1st High-Energy Physics Madagascar International Conference Series (HEP-MAD'01) 27th sept-5th oct. 2001, Antananarivo

Ref HAL: hal-00012088_v1
Ref Arxiv: hep-th/0110275
DOI: 10.1103/PhysRevA.65.032120
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
17 citations
Résumé:

Multiple scale techniques are well-known in classical mechanics to give perturbation series free from resonant terms. When applied to the quantum anharmonic oscillator, these techniques lead to interesting features concerning the solution of the Heisenberg equations of motion and the Hamiltonian spectrum.

Commentaires: 18 pages

Ref Arxiv: hep-ph/0110141
DOI: 10.1016/S0370-2693(01)01274-6
Ref. & Cit.: NASA ADS
72 citations
Résumé:

We consider an interpretation of the recent lattice data on the current-current correlators in the x-space. The data indicate rather striking difference between (axial)vector and (pseudo)scalar channels which goes beyond the predictions of the standard non-perturbative models. We argue that if the difference is to be explained by power corrections, there is a unique choice of the form of the correction. We discuss the emerging picture of the power corrections.