545 research outputs found

    SOFTSUSY: a program for calculating supersymmetric spectra

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    SOFTSUSY is a program which accurately calculates the spectrum of superparticles in the CP-conserving Minimal Supersymmetric Standard Model (MSSM), with a full flavour mixing structure. The program solves the renormalisation group equations with theoretical constraints on soft supersymmetry breaking terms provided by the user. Weak-scale gauge coupling and fermion mass data (including one-loop finite MSSM corrections) are used as a boundary condition, as well as successful radiative electroweak symmetry breaking. The program can also calculate a measure of fine-tuning. The program structure has been designed to easily generalise to extensions of the MSSM. This article serves as a self-contained guide to prospective users, and indicates the conventions and approximations used.Comment: Updated for SOFTSUSY3.3.3. Can be downloaded from http://projects.hepforge.org/softsusy/ Further updated versions of the manual will be distributed with the cod

    Naturalness Priors and Fits to the Constrained Minimal Supersymmetric Standard Model

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    We examine the effect of a prior that favours low values of fine-tuning on Bayesian multi-dimensional fits of the constrained minimal supersymmetric standard model (CMSSM or mSUGRA) to current data. The dark matter relic density, the anomalous magnetic moment of the muon and the branching ratio of b->s gamma are all used to constrain the model via a Markov Chain Monte Carlo sampler. As a result of the naturalness prior, posterior probability distributions skew towards lighter higgs and sparticle masses, the effect being most pronounced in the gaugino sector. Interestingly, slepton masses are an exception and skew towards heavier masses. The lightest CP-even Higgs h^0-pole region becomes allowed at the 2 sigma level for the latest combination of measurements of m_t=172.7+/-2.9 GeV, provided we allow for a theoretical error in the prediction of its mass m_{h^0}. m_{h^0} is constrained to be less than 120 GeV at the 95% C.L. Probing the branching ratio of B_s->mu^+ mu^- to the level of 2 x 10^{-8}, as might be achieved by the Tevatron experiments, would cover 32% of the probability density, irrespective of which of the two priors is used.Comment: 15 pages, 5 figures. Ref adde

    SUSY Parameter Analysis at TeV and Planck Scales

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    Coherent analyses at future LHC and LC experiments can be used to explore the breaking mechanism of supersymmetry and to reconstruct the fundamental theory at high energies, in particular at the grand unification scale. This will be exemplified for minimal supergravity.Comment: 7 pages, 3 figures, uses espcrc2.sty (included), Proceedings, Loops and Legs 2004, Zinnowitz on Usedo

    Signals of neutralinos and charginos from gauge boson fusion at the CERN Large Hadron Collider

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    We point out that interesting signals of the non-strongly interacting sector of the supersymmetric standard model arise from the production of charginos and neutralinos via vector boson fusion (VBF) at the Large Hadron Collider (LHC). In particular, if R-parity is violated, the hadronically quiet signals of charginos and neutralinos through direct production get considerably suppressed. We show that in such cases, the VBF channel can be useful in identifying this sector through clean and background-free final states.Comment: 10 pages Latex, 8 figures, minor changes in text and few references added, to be published in Phys. Rev.

    R-parity violation effect on the top-quark pair production at linear colliders

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    We investigate in detail the effects of the R-parity lepton number violation in the minimal supersymmetric standard model (MSSM) on the top-quark pair production via both ee+e^--e^+ and γγ\gamma-\gamma collision modes at the linear colliders. We find that with the present experimental constrained /R\rlap/{R} parameters, the effect from /R\rlap/{R} interactions on the processes e+ettˉe^+e^-\to t\bar{t} and e+eγγttˉe^+e^- \to \gamma\gamma \to t\bar{t} could be significant and may reach -30% and several percent, respectively. Our results show that the /R\rlap/{R} effects are sensitive to the c.m.s. energy and the relevant /R\rlap/{R} parameters. However, they are not sensitive to squark and slepton masses when mq~400GeVm_{\tilde{q}} \geq 400 GeV (or ml~300GeVm_{\tilde{l}} \geq 300 GeV) and are almost independent on the tanβ\tan\betaComment: Accepted by Phys.Rev.

    Wild birds respond to flockmate loss by increasing their social network associations to others

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    Understanding the consequences of losing individuals from wild populations is a current and pressing issue, yet how such loss influences the social behaviour of the remaining animals is largely unexplored. Through combining the automated tracking of winter flocks of over 500 wild great tits (Parus major) with removal experiments, we assessed how individuals’ social network positions responded to the loss of their social associates. We found that the extent of flockmate loss that individuals experienced correlated positively with subsequent increases in the number of their social associations, the average strength of their bonds and their overall connectedness within the social network (defined as summed edge weights). Increased social connectivity was not driven by general disturbance or changes in foraging behaviour, but by modifications to fine-scale social network connections in response to losing their associates. Therefore, the reduction in social connectedness expected by individual loss may be mitigated by increases in social associations between remaining individuals. Given that these findings demonstrate rapid adjustment of social network associations in response to the loss of previous social ties, future research should examine the generality of the compensatory adjustment of social relations in ways that maintain the structure of social organizationThe work was funded by an NERC studentship and EGI Research Fellowship to J.A.F. and grants from the ERC and BBSRC (AdG 250164; BB/L006081/1) to B.C.S

    Flavour and Collider Interplay for SUSY at LHC7

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    The current 7 TeV run of the LHC experiment shall be able to probe gluino and squark masses up to values larger than 1 TeV. Assuming that hints for SUSY are found in the jets plus missing energy channel by the end of a 5 fb1^{-1} run, we explore the flavour constraints on three models with a CMSSM-like spectrum: the CMSSM itself, a Seesaw extension of the CMSSM, and Flavoured CMSSM. In particular, we focus on decays that might have been measured by the time the run is concluded, such as BsμμB_s\to\mu\mu and μeγ\mu\to e\gamma. We also analyse constraints imposed by neutral meson bounds and electric dipole moments. The interplay between collider and flavour experiments is explored through the use of three benchmark scenarios, finding the flavour feedback useful in order to determine the model parameters and to test the consistency of the different models.Comment: 44 pages, 15 figures; v3: minor corrections, added references, updated figures. Version accepted for publicatio

    Biochemical parameters of silver catfish (Rhamdia quelen) after transport with eugenol or essential oil of Lippia alba added to the water

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    The transport of live fish is a routine practice in aquaculture and constitutes a considerable source of stress to the animals. The addition of anesthetic to the water used for fish transport can prevent or mitigate the deleterious effects of transport stress. This study investigated the effects of the addition of eugenol (EUG) (1.5 or 3.0 mu L L-1) and essential oil of Lippia alba (EOL) (10 or 20 mu L L-1) on metabolic parameters (glycogen, lactate and total protein levels) in liver and muscle, acetylcholinesterase activity (AChE) in muscle and brain, and the levels of protein carbonyl (PC), thiobarbituric acid reactive substances (TBARS) and nonprotein thiol groups (NPSH) and activity of glutathione-S-transferase in the liver of silver catfish (Rhamdia quelen; Quoy and Gaimard, 1824) transported for four hours in plastic bags (loading density of 169.2 g L-1). The addition of various concentrations of EUG (1.5 or 3.0 mu L L-1) and EOL (10 or 20 mu L L-1) to the transport water is advisable for the transportation of silver catfish, since both concentrations of these substances increased the levels of NPSH antioxidant and decreased the TBARS levels in the liver. In addition, the lower liver levels of glycogen and lactate in these groups and lower AChE activity in the brain (EOL 10 or 20 mu L L-1) compared to the control group indicate that the energetic metabolism and neurotransmission were lower after administration of anesthetics, contributing to the maintenance of homeostasis and sedation status.Fundacao de Amparo a Pesquisa do Estado do Rio Grande do Sul (FAPERGS/PRONEX) [10/0016-8]; Conselho Nacional de Pesquisa e Desenvolvimento Cientifico (CNPq) [470964/2009-0]; Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES); CNPqinfo:eu-repo/semantics/publishedVersio

    Probing R-parity violating models of neutrino mass at the Tevatron via top Squark decays

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    We have estimated the limiting branching ratio of the R-parity violating (RPV) decay of the lighter top squark, \tilde t_1 \ar l^+ d (l=el=e or μ\mu and d is a down type quark of any flavor), as a function of top squark mass(\MST) for an observable signal in the di-lepton plus di-jet channel at the Tevatron RUN-II experiment with 2 fb1^{-1} luminosity. Our simulations indicate that the lepton number violating nature of the underlying decay dynamics can be confirmed via the reconstruction of \MST. The above decay is interesting in the context of RPV models of neutrino mass where the RPV couplings (λi3j\lambda'_{i3j}) driving the above decay are constrained to be small (\lsim 10^{-3} - 10^{-4} ). If t~1\tilde t_1 is the next lightest super particle - a theoretically well motivated scenario - then the RPV decay can naturally compete with the R-parity conserving (RPC) modes which also have suppressed widths. The model independent limiting BR can delineate the parameter space in specific supersymmetric models, where the dominating RPV decay is observable and predict the minimum magnitude of the RPV coupling that will be sensitive to Run-II data. We have found it to be in the same ballpark value required by models of neutrino mass, for a wide range of \MST. A comprehensive future strategy for linking top squark decays with models of neutrino mass is sketched.Comment: 28 pages, 14 Figure
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