38063506
One-loop renormalization of the two-dimensional linear sigma model and Gross-Neveu model at finite temperature.
We study the one-loop renormalization of the two-dimensional linear [sigma] model and Gross-Neveu model at finite temperature. To do this, we use thermo field dynamics and regard the Gross-Neveu model as a [ital Z][sub 3]=[ital Z][sub 4]=0 limit of the linear [sigma] model. We also derive the renormalization group equations with respect to a dimensional parameter [ital M].
9157111
Consequences of recent electroweak data and $W$ mass for the top quark and Higgs masses
We critically reexamine the precision tests of the standard model by coupling the current world average value of $M_W$ with the recent LEP electroweak data with the aid of a modified ZFITTER program to include the dominant two-loop and QCD-EW mixed terms. The results show a clear evidence of nonvanishing electroweak radiative corrections. The recent CDF $m_t$ is a solution of the minimal $\chi^2$-fits to the recent LEP data set and $M_W=80.23(18)~$ GeV but with a heavy Higgs scalar, i.e., $m_t=179~$ GeV and $m_H=300~$ GeV. We discuss how sensitive $m_t$ and $m_H$ are depending on the exact value of $M_W$ even within the present uncertainty, as well as on $\alpha_s$ and $\alpha (M_Z)$. We show how the future improvements on $M_W$ can discriminate different values of $m_t$ and $m_H$ from the electroweak data and provide a crucial and decisive test for the standard model.
15197087
Bounds and implications of neutrino magnetic moments from atmospheric neutrino data
The neutral current effects of the future high statistics atmospheric neutrino data can be used to distinguish the mechanisms between a ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ oscillation to a tau neutrino or to a sterile neutrino. However, if neutrinos possess large diagonal and/or transition magnetic moments, the neutrino magnetic moments can contribute to the neutral current effects which can be studied by the single ${\ensuremath{\pi}}^{0}$ production events in the Super-K data. This effect should be included in the future analyses of atmospheric data in the determination of ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ to tau or sterile neutrino oscillation.
118620261
Weak mixing angle and Higgs mass in Gauge-Higgs unification models with brane kinetic terms
A bstractWe show that the idea of Gauge-Higgs unification(GHU) can be rescued from the constraint of weak mixing angle by introducing localized brane kinetic terms in higher dimensional GHU models with bulk and simple gauge groups. We find that those terms lead to a ratio between Higgs and W boson masses, which is a little bit deviated from the one derived in the standard model. From numerical analysis, we find that the current lower bound on the Higgs mass tends to prefer to exceptional groups E6, 7, 8 rather than other groups like SU(3l), SO(2n+1), G2, and F4 in 6-dimensional (D) GHU models irrespective of the compactification scales. For the compactification scale below 1 TeV, the Higgs masses in 6D GHU models with SU(3l), SO(2n + 1), G2, and F4 groups are predicted to be less than the current lower bound unless a model parameter responsible for re-scaling SU(2) gauge coupling is taken to be unnaturally large enough. To see how the situation is changed in more higher dimensional GHU model, we take 7D S3/$ {\mathbb{Z}_2} $ and 8D T4/Z2 models. It turns out from our numerical analysis that these higher dimensional GHU models with gauge groups except for E6 can lead to the Higgs boson whose masses are predicted to be above the current lower bound only for the compatification scale above 1 TeV without taking unnaturally large value of the model parameter, whereas the Higgs masses in the GHU models with E6 are compatible with the current lower bound even for the compatification scale below 1 TeV.
122992590
Low energy effective Lagrangian for supersymmetric seesaw model
Seesaw model is an attractive model because it may explain baryogenesis through leptogenesis and also may explain the small neutrino mass. The supersymmetric seesaw model may be more attractive because the naturalness problem is absent in supersymmetric theory. Recently, the higgs mass correction due to leptons and sleptons loops is computed.1 In this talk, we report on the preliminary results on the one loop corrections of leptons and sleptons loops to the effective action of Higgs sector for super symmetric seesaw model. Our results show that the corrections to the mass parameters for Higgs sector are proportional to the soft breaking parameters of supersymmetric seesaw model, while for the quartic couplings of Higgs fields, the corrections are suppressed by inverse powers of the right-handed neutrino mass.
1381801
Probing the messenger of supersymmetry breaking by the muon anomalous magnetic moment
Motivated by the recently measured muon's anomalous magnetic moment $a_{\mu}$, we examine the supersymmetry contribution to $a_{\mu}$ in various mediation models of supersymmetry breaking which lead to predictive flavor conserving soft parameters at high energy scale. The studied models include dilaton/modulus-mediated models in heterotic string/$M$ theory, gauge-mediated model, no-scale or gaugino-mediated model, and also the minimal and deflected anomaly-mediated models. For each model, the range of $a^{SUSY}_{\mu}$ allowed by other experimental constraints, e.g. b --> s\gamma and the collider bounds on superparticle masses, is obtained together with the corresponding parameter region of the model. Gauge-mediated models with low messenger scale can give any $a^{SUSY}_{\mu}$ within the $2\sigma$ bound. In many other models, b --> s\gamma favors $a^{SUSY}_{\mu}$ smaller than either the $-1\sigma$ value ($26\times 10^{-10}$) or the central value ($42\times 10^{-10}$).
15772562
Increase of black hole entropy in higher curvature gravity.
We examine the Zeroth Law and the Second Law of black hole thermodynamics within the context of effective gravitational actions including higher curvature interactions. We show that entropy can never decrease for quasi-stationary processes in which a black hole accretes positive energy matter, independent of the details of the gravitational action. Within a class of higher curvature theories where the Lagrangian consists of a polynomial in the Ricci scalar, we use a conformally equivalent theory to establish that stationary black hole solutions with a Killing horizon satisfy the Zeroth Law, and that the Second Law holds in general for any dynamical process. We also introduce a new method for establishing the Second Law based on a generalization of the area theorem, which may prove useful for a wider class of Lagrangians. Finally, we show how one can infer the form of the black hole entropy, at least for the Ricci polynomial theories, by integrating the changes of mass and angular momentum in a quasistationary accretion process.