Yukawa Coupling Unification in SO(10) Supersymmetric Grand Unified Theories

We report on a preferred region of supersymmetric parameter space by t, b, tau Yukawa unification. We find a narrow region survives for mu > 0 (suggested by b --> s gamma and the anomalous magnetic moment of the muon) with A_0 \sim - 2 m_{16}, m_{16} > 1200 GeV, mu, M_{1/2} << m_{16} and tan \beta \sim 50 \pm 2. Demanding Yukawa unification thus makes definite predictions for Higgs and sparticle masses.Comment: 4 pages, Talk given at the 9th International Conference on Supersymmetry and Unification of Fundamental Interactions SUSY'01, June 11--17, Dubna, Russi

New constraints on a light CP-odd Higgs boson and related NMSSM Ideal Higgs Scenarios

Recent BaBar limits on \br(\Upsilon(3S)\to \gam a\to \gam \tau^+\tau^-) and \br(\Upsilon(3S)\to \gam a\to \gam \mu^+\mu^-) provide increased constraints on the a b\anti b coupling of a CP-odd Higgs boson, $a$, with $m_a<M_{\Upsilon(3S)}$. We extract these limits from the BaBar data and compare to the limits previously obtained using other data sets, especially the CLEO-III \br(\Upsilon(1S)\to \gam\to\tau^+\tau^-) limits. Comparisons are made to predictions in the context of "ideal"-Higgs NMSSM scenarios, in which the lightest CP-even Higgs boson, $h_1$, can have mass below 105\gev (as preferred by precision electroweak data) and yet can escape old LEP limits by virtue of decays to a pair of the lightest CP-odd Higgs bosons, $h_1\to a_1a_1$, with $m_{a_1}<2m_B$. Most such scenarios with $m_{a_1}<2m_\tau$ are eliminated, but the bulk of the m_{a_1}>7.5\gev scenarios, which are theoretically the most favored, survive. We also outline the impact of the new ALEPH LEP results in the \epem\to Z+4\tau channel. For $\tan\beta\geq 3$, only NMSSM ideal Higgs scenarios with m_{h_1}\gsim 98\gev and $m_{a_1}$ close to $2m_B$ satisfy the ALEPH limits. For \tan\beta\lsim 2, the ALEPH limits are easily satisfied for the most theoretically preferred NMSSM scenarios, which are those with $m_{a_1}$ close to $2m_B$ and m_{h_1}\sim 90\gev-100\gev.Comment: 24 pages, 25 figures, paper updated to incorporate final ALEPH limits in Z+4\tau channel

SO(10) SUSY GUT for Fermion Masses : Lepton Flavor and CP Violation

We discuss the results of a global $\chi^2$ analysis of a simple SO(10) SUSY GUT with $D_3$ family symmetry and low energy R parity. The model describes fermion mass matrices with 14 parameters and gives excellent fits to 20 observable masses and mixing angles in both quark and lepton sectors, giving 6 predictions. Bi-large neutrino mixing is obtained with hierarchical quark and lepton Yukawa matrices; thus avoiding the possibility of large lepton flavor violation. The model naturally predicts small 1-3 neutrino mixing, with $\sin \theta_{13} \simeq 0.05 - 0.06$. In this paper we evaluate the predictions for the lepton flavor violating processes, $\mu \to e \gamma$, $\tau \to \mu \gamma$ and $\tau \to e \gamma$ and also the electric dipole moment of the electron, $d_e$, muon and tau, assuming universal squark and slepton masses, $m_{16}$, and a universal soft SUSY breaking A parameter, $A_0$, at the GUT scale. We find $Br(\mu \to e \gamma)$ is naturally below present bounds, but may be observable by MEG. Similarly, $d_e$ is below present bounds; but is within the range of future experiments. We also give predictions for the light Higgs mass (using FeynHiggs). We find an upper bound given by $m_h \leq 127$ GeV, with an estimated $\pm 3$ GeV theoretical uncertainty. Finally we present predictions for SUSY particle masses in the favored region of parameter space.Comment: 25 pages, 18 figures, several typos in captions of tables 2 and 3 corrected, acknowledgments adde

The Higgs Penguin and its Applications : An overview

We review the effective Lagrangian of the Higgs penguin in the Standard Model and its minimal supersymmetric extension (MSSM). As a master application of the Higgs penguin, we discuss in some detail the B-meson decays into a lepton-antilepton pair. Furthermore, we explain how this can probe the Higgs sector of the MSSM provided that some of these decays are seen at Tevatron Run II and B-factories. Finally, we present a complete list of observables where the Higgs penguin could be strongly involved.Comment: 22 pages, 6 figures, Invited review article to appear in Mod. Phys. Lett. A, v2: Table 1 updated, comments and references adde

Supersymmetric Higgs Singlet Effects on B-Meson FCNC Observables at Large tan(beta)

Higgs singlet superfields are usually present in most extensions of the Minimal Supersymmetric Standard Model (MSSM) that address the mu-problem, such as the Next-to-Minimal Supersymmetric Standard Model (NMSSM) and the Minimal Nonminimal Supersymmetric Standard Model (MNSSM). Employing a gauge- and flavour-covariant effective Lagrangian formalism, we show how the singlet Higgs bosons of such theories can have significant contributions to B-meson flavour-changing neutral current (FCNC) observables for large values of $\tan\beta \stackrel{>}{{}_\sim} 50$ at the 1-loop level. Illustrative results are presented including effects on the B_s and B_d mass differences and on the rare decay $B_s\to\mu^+\mu^-$. In particular, we find that depending on the actual value of the lightest singlet pseudoscalar mass in the NMSSM, the branching ratio for $B_s\to\mu^+\mu^-$ can be enhanced or even suppressed with respect to the Standard Model prediction by more than one order of magnitude.Comment: 28 pages, 8 figures, LaTeX. Minor updates. Version to be published in PR

Viable models with non-universal gaugino mediated supersymmetry breaking

Recently, extra dimensional SUSY GUT models have been proposed in which compactification of the extra dimension(s) leads to a breakdown of the gauge symmetry and/or supersymmetry. We examine a particular class of higher-dimensional models exhibiting supersymmetry and SU(5) or SO(10) GUT symmetry. SUSY breaking occurs on a hidden brane, and is communicated to the visible brane via gaugino mediation. Non-universal gaugino masses are developed at the compactification scale as a consequence of a restricted gauge symmetry on the hidden brane. In this case, the compactification scale is at or slightly below the GUT scale. We examine the parameter space of such models where gaugino masses are related due to a Pati-Salam symmetry on the hidden brane. We find limited but significant regions of model parameter space where a viable spectra of SUSY matter is generated. Our results are extended to the more general case of three independent gaugino masses; here we find that large parameter space regions open up for large values of the U(1) gaugino mass M_1. We also find the relic density of neutralinos for these models to be generally below expectations from cosmological observations, thus leaving room for hidden sector states to make up the bulk of cold dark matter. Finally, we evaluate the branching fraction BF(b -> s gamma) and muon anomalous magnetic moment a_\mu.Comment: 21 pages, 9 figure

Review of Heavy Quark Physics - theory

Recent progress in the theory of B-meson decays is reviewed with emphasis on the aspects related to the B-factory data.Comment: 15 pages; Invited Plenary Talk at the 32nd International Conference on High Energy Physics (ICHEP'04), Beijing, China, Aug. 16-22, 200