Ref HAL: in2p3-00142888_v1
Ref Arxiv: hep-ph/0211331
DOI: 10.1016/j.cpc.2006.11.009
WoS: 000245302600004
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
623 Citations
Résumé:

We present the Fortran code SuSpect version 2.3, which calculates the Supersymmetric and Higgs particle spectrum in the Minimal Supersymmetric Standard Model (MSSM). The calculation can be performed in constrained models with universal boundary conditions at high scales such as the gravity (mSUGRA), anomaly (AMSB) or gauge (GMSB) mediated supersymmetry breaking models, but also in the non-universal MSSM case with R-parity and CP conservation. Care has been taken to treat important features such as the renormalization group evolution of parameters between low and high energy scales, the consistent implementation of radiative electroweak symmetry breaking and the calculation of the physical masses of the Higgs bosons and supersymmetric particles taking into account the dominant radiative corrections. Some checks of important theoretical and experimental features, such as the absence of non-desired minima, large fine-tuning in the electroweak symmetry breaking condition, as well as agreement with precision measurements can be performed. The program is simple to use, self-contained and can easily be linked to other codes; it is rather fast and flexible, thus allowing scans of the parameter space with several possible options and choices for model assumptions and approximations.

Commentaires: This paper and its associated computer program are available via the Computer Physics Communications homepage on ScienceDirect http://www.sciencedirect.com/science/journal/00104655)

Ref HAL: hal-00327600_v1
Ref Arxiv: cond-mat/0207295
DOI: 10.1103/PhysRevA.68.043615
WoS: 000188711400029
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
37 Citations
Résumé:

We investigate the convergence properties of optimized perturbation theory, or linear delta expansion (LDE), within the context of finite temperature phase transitions. Our results prove the reliability of these methods, recently employed in the determination of the critical temperature Tc for a system of a weakly interacting homogeneous dilute Bose gas. We carry out explicit LDE optimized calculations and also the infrared analysis of the relevant quantities involved in the determination of Tc in the large-N limit, when the relevant effective static action describing the system is extended to O(N) symmetry. Then, using an efficient resummation method, we show how the LDE can already exactly reproduce the known large-N result for Tc at the first nontrivial order. Next, we consider the finite N = 2 case where, using similar resummation techniques, we improve the analytical results for the nonperturbative terms involved in the expression for the critical temperature, allowing comparison with recent Monte Carlo estimates of them. To illustrate the method, we have considered a simple geometric series showing how the procedure as a whole works consistently in a general case.

Ref Arxiv: cond-mat/0207089
DOI: 0.1103/PhysRevLett.89.210403
Ref. & Cit.: NASA ADS
Résumé:

The linear δ expansion (LDE) is applied to the critical O(N) ϕ4 three-dimensional field theory which has been widely used to study the temperature of condensation of dilute weakly interacting homogeneous Bose gases. We study the higher order convergence of the LDE as it is usually applied to this problem. We show how to improve both the large N and finite N=2 LDE results with an efficient resummation technique which accelerates convergence. In the large N limit, it reproduces the known exact result within numerical integration accuracy. In the finite N=2 case, our improved results support the recent numerical Monte Carlo estimates for the transition temperature.

Ref Arxiv: hep-ph/0106315
Ref. & Cit.: NASA ADS
Résumé:

The TESLA Technical Design Report Part III: Physics at an e+e- Linear Collider

Commentaires: 192 pages, 131 figures. Some figures have reduced quality. Full quality figures can be obtained from this http URL Editors - R.-D. Heuer, D.J. Miller, F. Richard, P.M. Zerwas

Ref HAL: hal-00307942_v1
Ref Arxiv: hep-th/0205133
DOI: 10.1103/PhysRevD.66.085020
WoS: 000179081500072
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
19 Citations
Résumé:

We reconsider in some detail a construction allowing (Borel) convergence of an alternative perturbative expansion, for specific physical quantities of asymptotically free models. The usual perturbative expansions (with an explicit mass dependence) are transmuted into expansions in 1/F, where F∼1/g(m) for m≫Λ while F∼(m/Λ)α for m≲Λ, Λ being the basic scale and α given by renormalization group coefficients. (Borel) convergence holds in a range of F which corresponds to reach unambiguously the strong coupling infrared regime near m→0, which can define certain “nonperturbative” quantities, such as the mass gap, from a resummation of this alternative expansion. Convergence properties can be further improved, when combined with δ expansion (variationally improved perturbation) methods. We illustrate these results by reevaluating, from purely perturbative information, the O(N) Gross-Neveu model mass gap, known for arbitrary N from exact S matrix results. Comparing different levels of approximations that can be defined within our framework, we find reasonable agreement with the exact result.

Ref HAL: hal-00324036_v1
Ref Arxiv: hep-th/0111120
DOI: 10.1088/1126-6708/2003/01/014
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé:

The exact mass gap of the O(N) Gross-Neveu model is known, for arbitrary N, from non-perturbative methods. However, a ``naive" perturbative expansion of the pole mass exhibits an infinite set of infrared renormalons at order 1/N, formally similar to the QCD heavy quark pole mass renormalons, potentially leading to large Script O(?) perturbative ambiguities. We examine the precise vanishing mechanism of such infrared renormalons, which avoids this (only apparent) contradiction, and operates without need of (Borel) summation contour prescription, usually preventing unambiguous separation of perturbative contributions. As a consequence we stress the direct Borel summability of the (1/N) perturbative expansion of the mass gap. We briefly speculate on a possible similar behaviour of analogous non-perturbative QCD quantities.

Ref HAL: hal-00265414_v1
Ref Arxiv: hep-ph/0107316
DOI: 10.1088/1126-6708/2001/08/055
WoS: 000174170100055
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
205 Citations
Résumé:

We perform a complete analysis of the supersymmetric particle spectrum in the Minimal Supergravity (mSUGRA) model where the soft SUSY breaking scalar masses, gaugino masses and trilinear couplings are unified at the GUT scale, so that the electroweak symmetry is broken radiatively. We show that the present constraints on the Higgs boson and superparticle masses from collider searches and precision measurements still allow for large regions of the mSUGRA parameter space where charginos, neutralinos, sleptons and top squarks as well as the heavier Higgs particles, are light enough to be produced at the next generation of e+e- linear colliders with center of mass energy around √s ~ 800 GeV, with sizeable cross sections. An important part of this parameter space remains even when we require that the density of the lightest neutralinos left over from the Big Bang, which we calculate using standard assumptions, falls in the range favored by current determinations of the Dark Matter density in the Universe. Already at a c.m. energy of 500 GeV, SUSY particles can be accessible in some parameter range, and if the energy is increased to √s simeq 1.2 TeV, the e+e- collider will have a reach for high precision studies of SUSY particles in a range that is comparable to the discovery range of the LHC.

Commentaires: LaTeX with epsfig.sty; 66 pages incl. 16 color PS figures. v2: updated references, slight change in FN16