Neutralino polarization effect in the squark cascade decay at LHC

We study the effect of the neutralino polarization in a squark cascade decay $\tilde{q} \to q \tilde{\chi}^0_2 \to q l^\pm \tilde{l}^\mp \to q l^\pm \tilde{l}^\mp \to q l^\pm l^\mp \tilde{\chi}^0_1$. Charge asymmetry in the lepton-jet invariant mass distribution appears depending on the chirality structure of the sfermion-fermion-neutralino coupling. With use of the Monte Carlo simulation, we show that the asymmetry is measurable in LHC. We also show that the distribution of the charge asymmetry is sensitive to the (s)lepton flavor.Comment: 4 pages. Talk given at the 12th International Conference on Suypersymmetry and Unification of the Fundamental Interactions (SUSY04), June 17-23, 2004, in Epochal Tsukuba, Tsukuba, Japa

Exploring Flavor Structure of SUSY Breaking from B Decays and the Unitarity Triangle

We study effects of SUSY particles in the unitarity triangle analysis and the CP asymmetries in b -> s decays. We consider three different SUSY models, the minimal supergravity, SU(5) SUSY GUT with right-handed neutrinos, and MSSM with U(2) flavor symmetry, and show that the patterns and correlations of deviations from the standard model will be useful to discriminate the different SUSY models in future B experiments.Comment: 4 pages. Talk given at the 12th International Conference on Suypersymmetry and Unification of the Fundamental Interactions (SUSY04), June 17-23, 2004, in Epochal Tsukuba, Tsukuba, Japa

New constraint on the minimal SUSY GUT model from proton decay

We present results of reanalysis on proton decay in the minimal SU(5) SUSY GUT model. Unlike previous analyses, we take into account a Higgsino dressing diagram of dimension 5 operator with right-handed matter fields ($RRRR$ operator). It is shown that this diagram gives a significant contribution for $p \to K^{+}\bar{\nu}_{\tau}$. Constraints on the colored Higgs mass $M_C$ and the sfermion mass $m_{\tilde{f}}$ from Super-Kamiokande limit become considerably stronger than those in the previous analyses: M_C > 6.5\times 10^{16} \gev for m_{\tilde{f}} < 1 \tev. The minimal model with m_{\tilde{f}} \lsim 2 \tev is excluded if we require the validity of this model up to the Planck scale.Comment: Talk given by T. Nihei in International Symposium on Supersymmetry, Supergravity, and Superstring (SSS99), Seoul, Korea, June 23-27, 1999, based on the published work hep-ph/9808255. A reference adde

B0B^0--B‾0\overline{B}^0 mixing and ϵK\epsilon_K parameter in the minimal supergravity model

\bb mixing and a CP violation parameter in \kk mixing $\epsilon_K$ are studied in the minimal supergravity model. We solve the one-loop renormalization group equations for the minimal supersymmetric standard model (MSSM) parameters numerically in order to determine the masses and mixings of the supersymmetric particles, while all off-diagonal (generation mixing) elements and phases of Yukawa coupling matrices and those of squark mass matrices are taken into account. Applying the radiative electroweak symmetry breaking condition and phenomenological constraints including the recent measurement of the \bsg inclusive branching ratio, we obtain the allowed parameter region. We have found that the present constraints still allow a parameter region where both \bb mass splitting $\Delta M_B$ and $\epsilon_K$ are $\sim 20$\% larger than the standard model values. By explicit numerical calculations, we have also found that the complex phase of \bb mixing matrix element in this model is almost the same as the standard model value in a good accuracy in the whole allowed parameter region. It is shown that $\Delta M_B$ and $\epsilon_K$ can put useful constraints on the supersymmetry's parameter space when the Cabibbo-Kobayashi-Maskawa matrix elements are determined through the measurements of CP violations in $B$ decay with future $B$-factories.Comment: LaTeX, 23 pages + 12 figures (not included). Figures are available upon request or at ftp://tuhep.phys.tohoku.ac.jp/preprints/kek-th-445-figures.tar.g

Lepton flavor violating ZZ-boson couplings from non-standard Higgs interactions

The Standard Model predicts that the Higgs boson couples to the fermions in the mass eigenstates. We consider the effects of lepton flavor violating (LFV) $Z$ boson couplings in the case where the Higgs boson has flavor non-diagonal Yukawa interactions with the muon and the tau lepton generated from physics beyond the Standard Model. We list the formulae of the couplings of the effective interactions among the $\tau$ lepton, the muon and the $Z$ boson. Using these formulae, we calculate the branching fractions of various leptonic and hadronic LFV $\tau$ decays, and the LFV $Z$ boson decay: $Z\to \tau\mu$. Although the $Z$-boson contributions to LFV tau decays cannot be ignored in terms of the counting of operator dimensions or chirality flipptings, it turns out that they are not very significant for $\tau\to3\mu$ and $\tau\to\mu\rho$ decays. We also calculate the branching fractions of the processes, $\tau\to \mu\pi$, $\tau\to \mu\eta^{(\prime)}$ and $\tau\to\mu a_1$, which are dominated by the $Z$-boson exchanges due to the spin and the parity of the hadrons.Comment: 24 pages, 10 figure

Flavor changing neutral current processes and the muon anomalous magnetic moment in the supergravity model

Flavor changing neutral current processes in B and K decays in the supergravity model are revisited taking into account the recent progress of Higgs boson search experiments at LEP. Possible deviations of B^0--$\bar{B}^0$ mixing, the CP violating K^0--$\bar{K}^0$ mixing parameter $\epsilon_K$ from the standard model predictions are reduced significantly in a small $\tan\beta$ region due to the constraints on the SUSY parameter space imposed by the Higgs boson search. With the present bound on the Higgs boson mass, the magnitude of the B^0--$\bar{B}^0$ mixing amplitude can be enhanced up to 12% for \tanb=3 in the minimal supergravity. If we relax the strict universality of SUSY breaking scalar masses at the GUT scale, the deviation can be 25%. We also investigate SUSY contributions to the muon anomalous magnetic moment in the supergravity model and show that there is a correlation with the $b \to s \gamma$ amplitude. The SUSY contribution to $a_\mu = \frac{(g-2)_\mu}{2}$ can be (-30 -- $+80)\times 10^{-10}$ for $\tan\beta=10$ and even larger for larger $\tan\beta$. The improved measurement of the muon anomalous magnetic moment in the on-going experiment at BNL will put a strong constraint on SUSY parameter space, especially for a large $\tan\beta$ region.Comment: LaTeX-2e, 42 pages, 23 figure

b→sllˉb \to s l \bar l in the minimal supergravity model

The $b \rightarrow s l^+ l^-$ process is studied in the minimal supergravity model in detail. Taking account of the long distance contributions from the $c\overline{c}$ resonances, we calculate the branching ratio and the lepton forward-backward asymmetry in this model. We find that there is a strong correlation between the branching ratios of $b \rightarrow s \gamma$ and $b \rightarrow s l^+ l^-$ processes and that the interference effect can change the $b \rightarrow s l^+ l^-$ branching ratio in the off-resonance regions by up to $\pm 15$ depending on the relative phase between the long and short distance contributions. Using various phenomenological constraints including the branching ratio of $b \rightarrow s \gamma$, we show that there are regions in the parameter space where the branching ratio of $b \rightarrow s l^+ l^-$ is enhanced by about 50% compared to the SM. We also show that the branching ratio of $b \rightarrow s \nu{\overline \nu}$ is reduced at most by 10% from the SM prediction.Comment: LaTeX, 52 pages including figure

Neutrino oscillation, SUSY GUT and B decay

Effects of supersymmetric particles on flavor changing neutral current and lepton flavor violating processes are studied in the supersymmetric SU(5) grand unified theory with right-handed neutrino supermultiplets. Using input parameters motivated by neutrino oscillation, it is shown that the time-dependent CP asymmetry of radiative B decay can be as large as 30% when the $\tau \to \mu \gamma$ branching ratio becomes close to the present experimental upper bound. We also show that the $B_s$--$\bar{B}_s$ mixing can be significantly different from the presently allowed range in the standard model.Comment: RevTeX 3.1, 13 pages, 3 EPS figures include

Neutrino Yukawa couplings and FCNC processes in B decays in SUSY-GUT

Flavor changing neutral current and lepton flavor violating processes are studied in the SU(5) SUSY-GUT with right-handed neutrino supermultiplets. Using input parameters motivated by neutrino oscillation, it is shown that the time-dependent CP asymmetry of $b \to s \gamma$ can be as large as 20%. We also show that the $B_s$-$\bar{B}_s$ mixing can be significantly different from the standard model prediction.Comment: Talk given in International Seminar Quarks-2000, May 14-21, 2000, Pushkin, Russia and ICHEP 2000, July 27-August 2, 2000, Osaka, Japa

Charged Higgs mass bound from the b→sγb\rightarrow s\gamma process in the minimal supergravity model

We study the constraint on the mass of the charged Higgs boson in the minimal supergravity model based on the recent measurement of the inclusive $b\rightarrow s\gamma$ decay. It is shown that the lower bound for the charged Higgs mass crucially depends on the sign of the higgsino mass parameter ($\mu$). For $\mu<0$, the bound exceeds 400 GeV when the ratio of two Higgs vacuum expectation values ($\tan\beta$) is larger than 10. No strong bound is obtained for $\mu>0$ due to cancellations between charged Higgs and supersymmetric particle contributions. For 3\lsim\tan\beta\lsim5, a charged Higgs lighter than 180 GeV is excluded by this process irrespective of the sign of $\mu$.Comment: 19 pages, 8 EPS figures (appended in tar-gzip-uuencoded form