Authors
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Tag
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Content
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Author
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Baro , N. and Boudjema , F. and Semenov , A. |
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Title
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Full one-loop corrections to the relic density in the MSSM, a few examples |
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Year
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2007 |
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Abstract
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We show the impact of the electroweak, and in one instance the QCD, one-loop corrections on the relic density of dark matter in the MSSM which is provided by the lightest neutralino. We cover here some of the most important scenarii: annihilation into fermions for a bino-like neutralino, annihilation involving gauge bosons in the case of a mixed neutralino, the neutralino-stau co-annihilation region and annihilation into a bottom quark pair. The corrections can be large and should be taken into account in view of the present and forthcoming increasing precision on the relic density measurements. Our calculations are made possible thanks to a newly developed automatic tool for the calculation at one-loop of any process in the MSSM. We have implemented a complete on-shell gauge invariant renormalisation scheme, with the possibility of switching to other schemes. In particular we will report on the impact of different renormalisation schemes for tan beta. |
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Eprint
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http://arxiv.org/abs/0710.1821 |
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Journal
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Phys. Lett. |
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Month
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October |
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Pages
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550-560 |
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Slaccitation
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%%CITATION = ARXIV:0710.1821;%% |
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Volume
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B660 |
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URL
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http://arxiv.org/abs/0710.1821 |
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Tag
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Content
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Author
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Baro , N. and Boudjema , F. and Semenov , A. |
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Title
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Automatised full one-loop renormalisation of the MSSM I: The Higgs sector, the issue of tan(beta) and gauge invariance |
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Year
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2008 |
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Abstract
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We give an extensive description of the renormalisation of the Higgs sector of the minimal supersymmetric model in SloopS. SloopS is an automatised code for the computation of one-loop processes in the MSSM. In this paper, the first in a series, we study in detail the non gauge invariance of some definitions of tan(beta). We rely on a general non-linear gauge fixing constraint to make the gauge parameter dependence of different schemes for tan(beta) at one-loop explicit. In so doing we update, within these general gauges, an important Ward-Slavnov-Taylor identity on the mixing between the pseudo-scalar Higgs, A^0, and the Z^0. We then compare the tan(beta) scheme dependence of a few observables. We find that the best tan(beta) scheme is the one based on the decay A^0 -> tau^+ tau^- because of its gauge invariance, being unambiguously defined from a physical observable, and because it is numerically stable. The oft used DRbar scheme performs almost as well on the last count, but is usually defined from non-gauge invariant quantities in the Higgs sector. The use of the heavier scalar Higgs mass in lieu of tan(beta) though related to a physical parameter induces too large radiative corrections in many instances and is therefore not recommended. |
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Archiveprefix
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arXiv |
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Eprint
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http://arxiv.org/abs/0807.4668 |
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Month
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07 |
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Primaryclass
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hep-ph |
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Slaccitation
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%%CITATION = 0807.4668;%% |
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URL
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http://arxiv.org/abs/0807.4668 |
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Tag
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Content
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Author
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Belanger , G. and Boudjema , F. and Pukhov , A. and Semenov , A. |
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Title
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Dark matter direct detection rate in a generic model with micromegas 2.1 |
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Year
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2008 |
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Abstract
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We present a new module of the micrOMEGAs package for the calculation of WIMP-nuclei elastic scattering cross sections relevant for the direct detection of dark matter through its interaction with nuclei in a large detector. With this new module, the computation of the direct detection rate is performed automatically for a generic model of new physics which contains a WIMP candidate. This model needs to be implemented within micrOMEGAs2.1. |
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Slaccitation
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%%CITATION = ARXIV:0803.2360;%% |
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URL
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http://arxiv.org/abs/0803.2360 |
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Tag
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Content
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Author
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Belanger , G. and Kittel , O. and Kraml , S. and Martyn , H. -U. and Pukhov , A. |
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Title
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Neutralino relic density from ILC measurements in the CPV MSSM |
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Year
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2008 |
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Abstract
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We
discuss ILC measurements for a specific MSSM scenario with CP phases,
where the lightest neutralino is a good candidate for dark matter,
annihilating efficiently through t-channel exchange of light staus.
These prospective (CP-even) ILC measurements are then used to fit the
underlying model parameters. A collider prediction of the relic density
of the neutralino from this fit gives 0.116 |
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Slaccitation
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%%CITATION = ARXIV:0803.2584;%% |
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URL
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http://arxiv.org/abs/0803.2584 |
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Tag
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Content
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Author
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Belanger , G. and Nezri , E. and Pukhov , A. |
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Title
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Discriminating dark matter candidates using direct detection |
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Year
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2008 |
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Abstract
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We examine the predictions for both the spin dependent and spin independent direct detection rates in a variety of new particle physics models with dark matter candidates. We show that a determination of both spin independent and spin dependent amplitudes on protons and neutrons can in principle discriminate different candidates of dark matter up to a few ambiguities. We emphasize the importance of making measurements with different spin dependent sensitive detector materials and the need for significant improvement of the detector sensitivities. Scenarii where exchange of new coloured particles contributes significantly to the elastic scattering cross sections are often the most difficult to identify, the LHC should give an indication whether such scenarii are relevant for direct detection. |
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Archiveprefix
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arXiv |
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Eprint
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http://arxiv.org/abs/0810.1362 |
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Month
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10 |
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Primaryclass
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hep-ph |
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Slaccitation
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%%CITATION = 0810.1362;%% |
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URL
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http://arxiv.org/abs/0810.1362 |
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Tag
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Content
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Author
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Berger , Carola F. and Covi , Laura and Kraml , Sabine and Palorini , Federica |
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Title
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The number density of a charged relic |
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Year
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2008 |
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Abstract
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We investigate scenarios in which a charged, long-lived scalar particle decouples from the primordial plasma in the Early Universe. We compute the number density at time of freeze-out considering both the cases of abelian and non-abelian interactions and including the effect of Sommerfeld enhancement at low initial velocity. We also discuss as extreme case the maximal cross section that fulfils the unitarity bound. We then compare these number densities to the exotic nuclei searches for stable relics and to the BBN bounds on unstable relics and draw conclusions for the cases of a stau or stop NLSP in supersymmetric models with a gravitino or axino LSP. |
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Archiveprefix
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arXiv |
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Eprint
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http://arxiv.org/abs/0807.0211 |
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Primaryclass
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hep-ph |
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Slaccitation
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%%CITATION = 0807.0211;%% |
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URL
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http://arxiv.org/abs/0807.0211 |
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Tag
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Content
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Author
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Degrassi , G. and Gambino , P. and Slavich , P. |
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Title
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SusyBSG: a fortran code for BR[B -> Xs gamma] in the MSSM |
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Year
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2007 |
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Archiveprefix
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arXiv |
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Eprint
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http://arxiv.org/abs/0712.3265 |
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Month
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December |
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Primaryclass
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hep-ph |
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Slaccitation
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%%CITATION = 0712.3265;%% |
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URL
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http://arxiv.org/abs/0712.3265 |
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Tag
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Content
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Author
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Degrassi , G. and Slavich , P. |
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Title
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On the NLO QCD corrections to Higgs production and decay |
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Year
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2008 |
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Abstract
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We present explicit analytic results for the two-loop top/stop/gluino contributions to the cross section for Higgs boson production via gluon fusion in the MSSM, under the approximation of neglecting the Higgs boson mass with respect to the masses of the particles circulating in the loops. The results are obtained employing the low-energy theorem for Higgs interactions adapted to the case of particle mixing. We discuss the validity of the approximation used by computing the first-order correction in an expansion in powers of the Higgs boson mass. We find that, for the lightest CP-even Higgs boson, the gluino contribution is very well approximated by the result obtained in the limit of vanishing Higgs mass. As a byproduct of our calculation, we provide results for the two-loop QCD contributions to the photonic Higgs decay. |
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Archiveprefix
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arXiv |
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Eprint
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http://arxiv.org/ps/0806.1495 |
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Primaryclass
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hep-ph |
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Slaccitation
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%%CITATION = 0806.1495;%% |
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URL
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http://arxiv.org/abs/0806.1495 |
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Tag
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Content
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Author
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Semenov , Andrei |
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Title
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LanHEP - a package for the automatic generation of Feynman rules in field theory, version 3.0 |
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Year
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2008 |
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Abstract
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The LanHEP program version 3.0 for Feynman rules generation from the Lagrangian is described. It reads the Lagrangian written in a compact form, close to the one used in publications. It means that Lagrangian terms can be written with summation over indices of broken symmetries and using special symbols for complicated expressions, such as covariant derivative and strength tensor for gauge fields. Supersymmetric theories can be described using the superpotential formalism and the 2-component fermion notation. The output is Feynman rules in terms of physical fields and independent parameters in the form of CompHEP model files, which allows one to start calculations of processes in the new physical model. Alternatively, Feynman rules can be generated in FeynArts format or as LaTeX table. One-loop counterterms can be generated in FeynArts format. |
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URL
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http://arxiv.org/abs/0805.0555 |
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