Ref HAL: hal-00266464_v1
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Résumé:

A review of the activity of the European Network ``Physics at Colliders'' in the area of SUSY particle physics is presented.

Commentaires: Meeting of the European Network "Physics at Colliders", Montpellier (France) Sept-26-27 , 2004.

Ref HAL: hal-00259668_v1
Ref Arxiv: cond-mat/0408538
DOI: 10.1103/PhysRevA.71.033613
WoS: 000228632400037
Ref. & Cit.: NASA ADS
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16 Citations
Résumé:

In the framework of the O(N) three-dimensional effective scalar field model for homogeneous dilute weakly interacting Bose gases we use the 1/N expansion to evaluate, within the large N limit, the parameter r_c which is directly related to the critical chemical potential mu_c. This quantity enters the order-a^2 n^{2/3} coefficient contributing to the critical temperature shift Delta T_c where a represents the s-wave scattering length and n represents the density. Compared to the recent precise numerical lattice simulation results, our calculation suggests that the large N approximation performs rather well even for the physical case N=2. We then calculate the same quantity but using different forms of the optimized perturbative (variational) method, showing that these produce excellent results both for the finite N and large-N cases.

Commentaires: 12 pages, 2 figures. We have performed a refined and extended numerical analysis to take into account the very recent results of Ref. [15]

Ref HAL: hal-00259672_v1
Ref Arxiv: cond-mat/0401324
DOI: 10.1103/PhysRevA.69.053624
WoS: 000221813700139
Ref. & Cit.: NASA ADS
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50 Citations
Résumé:

Improving perturbation theory via a variational optimization has generally produced in higher orders an embarrassingly large set of solutions, most of them unphysical (complex). We introduce an extension of the optimized perturbation method which leads to a drastic reduction of the number of acceptable solutions. The properties of this new method are studied and it is then applied to the calculation of relevant quantities in different $\phi^4$ models, such as the anharmonic oscillator energy levels and the critical Bose-Einstein Condensation temperature shift $\Delta T_c$ recently investigated by various authors. Our present estimates of $\Delta T_c$, incorporating the most recently available six and seven loop perturbative information, are in excellent agreement with all the available lattice numerical simulations. This represents a very substantial improvement over previous treatments.

Commentaires: 9 pages

Ref Arxiv: hep-ph/0402295
Ref. & Cit.: NASA ADS
Résumé:

The work contained herein constitutes a report of the ``Beyond the Standard Model'' working group for the Workshop "Physics at TeV Colliders", Les Houches, France, 26 May--6 June, 2003. The research presented is original, and was performed specifically for the workshop. Tools for calculations in the minimal supersymmetric standard model are presented, including a comparison of the dark matter relic density predicted by public codes. Reconstruction of supersymmetric particle masses at the LHC and a future linear collider facility is examined. Less orthodox supersymmetric signals such as non-pointing photons and R-parity violating signals are studied. Features of extra dimensional models are examined next, including measurement strategies for radions and Higgs', as well as the virtual effects of Kaluza Klein modes of gluons. Finally, there is an update on LHC $Z'$ studies.

Commentaires: 3rd Les Houches Workshop: Physics at TeV Colliders, Les Houches (France) , May 26-June 6, 2003.

Ref Arxiv: hep-ph/0406166
DOI: 10.1088/1126-6708/2004/09/044
Ref. & Cit.: NASA ADS
Résumé:

We present the implementation of the radiative corrections of the Higgs sector in three public computer codes for the evaluation of the particle spectrum in the Minimal Supersymmetric Standard Model, SoftSusy, SPheno and SuSpect. We incorporate the full one-loop corrections to the Higgs boson masses and the electroweak symmetry breaking conditions, as well as the two-loop corrections controlled by the strong gauge coupling and the Yukawa couplings of the third generation fermions. We include also the corrections controlled by the τ Yukawa coupling that we derived for completeness. The computation is consistently performed in the bar Dbar R renormalisation scheme. In a selected number of MSSM scenarios, we study the effect of these corrections and analyse the impact of some higher order effects. By considering the renormalisation scheme and scale dependence, and the effect of the approximation of zero external momentum in the two-loop corrections, we estimate the theoretical uncertainty on the lighter Higgs boson mass to be 3 to 5 GeV. The uncertainty on M h due to the experimental error in the measurement of the SM input parameters is approximately of the same size. Finally, we discuss the phenomenological consequences, using the latest value of the top quark mass. We find, in particular, that the most conservative upper bound on the lighter Higgs boson mass in the general MSSM is Mhlesssim152 GeV and that there is no lower bound on the parameter tan β from non-observation of the MSSM Higgs bosons at LEP2.

Ref Arxiv: hep-ph/0311123
DOI: 10.1088/1126-6708/2004/07/036
WoS: 000224125000036
Ref. & Cit.: NASA ADS
217 Citations
Résumé:

An accord specifying a unique set of conventions for supersymmetric extensions of the Standard Model together with generic file structures for 1) supersymmetric model specifications and input parameters, 2) electroweak scale supersymmetric mass and coupling spectra, and 3) decay tables is presented, to provide a universal interface between spectrum calculation programs, decay packages, and high energy physics event generators.

Ref HAL: hal-00268367_v1
DOI: 10.1016/S0920-5632(03)01852-8
WoS: 000184039900051
Exporter : BibTex | endNote
Résumé:

We review a construction based on an expansion around a (mass) fixed point renormalization group solution, in asymptotically free models. It transmutes the usual perturbative expansion of certain physical quantities in such a way that the alternative expansion parameter 1/F behaves like the ordinary coupling: Image in the perturbative regime Image, but like a power of Image in the infrared regime Image (Imagein and Λ being the scale invariant mass and basic scale respectively). (Borel) convergence of the induced series can hold in a range of F corresponding to reach unambiguously the strong coupling infrared regime, near Image. We argue that certain nonperturbative quantities, such as the (pole) mass gap typically, can be thus obtained from a direct resummation of this alternative expansion (i.e. without adding intrinsically nonperturbative power-like contributions).