Ref HAL: in2p3-00677468_v1
Ref Arxiv: 1203.1488
Ref. & Cit.: NASA ADS
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Résumé:

We present the activities of the "New Physics" working group for the "Physics at TeV Colliders" workshop (Les Houches, France, 30 May-17 June, 2011). Our report includes new agreements on formats for interfaces between computational tools, new tool developments, important signatures for searches at the LHC, recommendations for presentation of LHC search results, as well as additional phenomenological studies.

Commentaires: 243 pages, report of the Les Houches 2011 New Physics Group

DOI: 10.1140/epjc/s10052-010-1520-2
WoS: 000291662700008
19 Citations
Résumé:

If supersymmetry is observed at the LHC its model parameters can be measured at the electroweak scale. We discuss the expected precision on the parameter determination, including a proper treatment of experimental and theoretical errors. Particular attention is paid to degenerate solutions. Using the SFitter framework we perform a bottom-up reconstruction of the unified parameters at the high scale, including a full error propagation.

Ref HAL: hal-00653509_v1
Ref Arxiv: 1108.3501
DOI: 10.1103/PhysRevD.85.014005
WoS: WOS:000298925900001
Ref. & Cit.: NASA ADS
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24 Citations
Résumé:

A recent extension of a variationally optimized perturbation, combined with renormalization group properties in a straightforward way, can provide approximations to nonperturbative quantities such as the chiral symmetry breaking order parameters typically. We apply this to evaluate, up to third order in this modified perturbation, the ratio Fpi/Lambda, where Fpi is the pion decay constant and Lambda the basic QCD scale in the modified MS scheme. Using experimental Fpi input value we obtain Lambda(nf=2) ~ 255_{-15}^{+40} MeV, where quoted errors are estimates of theoretical uncertainties of the method. This compares reasonably well with some recent lattice simulation results. We briefly discuss prospects (and obstacles) for extrapolation to alpha_S(mu) at perturbative mu values.

Commentaires: 5 pages

Ref HAL: hal-00653505_v1
Ref Arxiv: 1111.3455
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé:

We consider no-scale supergravity inspired scenarios, emphasizing the possible dynamical determination of the soft supersymmetry-breaking parameters as triggered by the radiative corrections that lift an essentially flat tree-level potential in the hidden sector. We (re)emphasize the important role played by the scale-dependent vacuum energy contribution to the effective potential for the occurrence of consistent no-scale minima. The most relevant input parameters are introduced as $B_0$ (the soft breaking mixing Higgs parameter) and $\eta_0$ (the cosmological constant value at high energy) instead of $\mhalf$ and $\tan \beta$, the latter being determined through a (generalized) potential minimization at electroweak scales. We examine the theoretical and phenomenological viability of such a mechanism when confronted with up-to-date calculations of the low energy sparticle spectrum and with present constraints from the LHC and other observables. The tight dark matter relic density constraint for a neutralino LSP scenario can be considerably relaxed for a gravitino LSP scenario possible in this framework.

Commentaires: Proceedings of the 2011 Europhysics Conference on High Energy Physics, EPS-HEP 2011, July 21-27, 2011 Grenoble, Rhône-Alpes, France

Ref HAL: hal-00608561_v1
Ref Arxiv: 1106.6325
DOI: 10.1103/PhysRevD.84.075015
WoS: WOS:000296882900001
Ref. & Cit.: NASA ADS
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4 Citations
Résumé:

We consider no-scale inspired supergravity scenarios, where the gravitinomass and related soft supersymmetry-breaking parameters are determineddynamically by radiative corrections to an essentially flat tree-levelpotential in the supersymmetry breaking hidden sector. We examine thetheoretical and phenomenological viability of such a mechanism, when includingup-to-date calculations of the low energy sparticle spectrum and taking intoaccount the latest LHC results and other experimental constraints. We(re)emphasize the role of the scale-dependent vacuum energy contribution to theeffective potential, in obtaining realistic no-scale electroweak minima,examining carefully the impact of boundary conditions and of variants of theminimization procedure. We also discuss and implement the B_0 (soft breakingHiggs mixing parameter) input boundary condition at high scale, thereforefixing tan beta(B_0) at low scales. For general high scale boundary conditionswith non-vanishing B_0, m_0..., our analysis provides theoretical correlationsamong the supersymmetric, soft and vacuum energy parameters and relatedphenomenological consequences at the LHC. For instance, a zero vacuum energy atthe GUT scale would lead to a decoupled supersymmetric spectrum, together witha light standard model-like Higgs boson at the electroweak scale. Given theexperimental exclusion limits, a substantial class of the boundary conditions,and in particular the strict no-scale with m_0=A_0=B_0=0, are only compatiblewith a stau being the lightest MSSM particle. Then an enlarged allowedparameter space emerges when assuming a gravitino LSP to account for theobserved dark matter relic density.

Ref HAL: in2p3-00534420_v1
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Ref HAL: hal-00494268_v1
Ref Arxiv: 1004.4834
DOI: 10.1103/PhysRevD.81.125012
WoS: 000278882200001
Ref. & Cit.: NASA ADS
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26 Citations
Résumé:

We introduce an extension of a variationally optimized perturbation method, by combining it with renormalization group properties in a straightforward (perturbative) form. This leads to a very transparent and efficient procedure, with a clear improvement of the non-perturbative results with respect to previous similar variational approaches. This is illustrated here by deriving optimized results for the mass gap of the O(2N) Gross-Neveu model, compared with the exactly know results for arbitrary N. At large N, the exact result is reproduced already at the very first order of the modified perturbation using this procedure. For arbitrary values of N, using the original perturbative information only known at two-loop order, we obtain a controllable percent accuracy or less, for any N value, as compared with the exactly known result for the mass gap from the thermodynamical Bethe Ansatz. The procedure is very general and can be extended straightforwardly to any renormalizable Lagrangian model, being systematically improvable provided that a knowledge of enough perturbative orders of the relevant quantities is available.

Commentaires: 18 pages, 1 figure