317 research outputs found

### 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

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