88 research outputs found
processes in the MSSM in large limit
We discuss corrections to , and to the CP
violation parameter in two examples of (generalized) minimal flavour
violation models: 2HDM and MSSM in the large limit. We show that
for not too heavy, in the MSSM with heavy sparticles can
be substantially smaller than in the SM due the charged Higgs box contributions
and in particular due to the growing like contribution of the
double penguin diagrams involving neutral Higgs boson exchanges.Comment: 5 pages, 2 Postscript figures, to appear in the proceedings of the
9th International Conference on Supersymmetry and Unification of Fundamental
Interactions SUSY'01, June 11-17, Dubna, Russi
SUSY_FLAVOR library for rare decays in the MSSM
SUSY_FLAVOUR 2.0 is a FORTRAN code calculating over 30 low-energy flavour-
and CP-related observables in the R-parity conserving MSSM. The code admits for
the most general flavour structure of the SUSY breaking terms and complex
flavour-diagonal couplings. It includes the numerically important resummation
of chirally enhanced effects and it is fast enough for scanning over a large
SUSY-parameter space. The program can be obtained from
http://www.fuw.edu.pl/susy_flavor.Comment: 3 pages, 1 table, proceedings for EPS-HEP201
Complete One-Loop MSSM Predictions for B --> lepton lepton' at the Tevatron and LHC
During the last few years the Tevatron has dramatically improved the bounds
on rare B-meson decays into two leptons. In the case of B_s --> mu+ mu-, the
current bound is only ten times greater than the Standard Model expectation.
Sensitivity to this decay is one of the benchmark goals for LHCb performance
and physics. The Higgs penguin dominates this rate in the region of large
tan(beta) of the MSSM. This is not necessarily the case in the region of low
tan(beta), since box and Z-penguin diagrams may contribute at a comparable
rate. In this article, we compute the complete one-loop MSSM contribution to B
--> l+l'- for l,l' = e, mu. We study the predictions for general values of
tan(beta) with arbitrary flavour mixing parameters. We discuss the possibility
of both enhancing and suppressing the branching ratios relative to their
Standard Model expectations. In particular, we find that there are
"cancellation regions" in parameter space where the branching ratio is
suppressed well below the Standard Model expectation, making it effectively
invisible to the LHC.Comment: 30 pages, 4 figures; v.3: corrected factors of (2 pi) in (2.11),
(3.1), (A.11), (A.13-14
K^+ -> pi^+ nu nu-bar and K_L -> pi^0 nu nu-bar Decays in the General MSSM
We reanalyze the rare decays K^+ -> pi^+ nu nu-bar and K_L -> pi^0 nu nu-bar
in a general MSSM with conserved R-parity. Working in the mass eigenstate basis
and performing adaptive scanning of a large space of supersymmetric parameters,
16 parameters in the constrained scan and 63 in the extended scan, we find that
large departures from the Standard Model expectations are possible while
satisfying all existing constraints. Both branching ratios can be as large as a
few times 10^{-10} with Br(K_L -> pi^0 nu nu-bar) often larger than Br(K^+ ->
pi^+ nu nu-bar) and close to its model independent upper bound. We give
examples of supersymmetric parameters for which large departures from the SM
expectations can be found and emphasize that the present 90% C.L. experimental
upper bound on Br(K^+ -> pi^+ nu nu-bar) gives a non trivial constraint on the
MSSM parameter space. Unlike previous analyses, we find that chargino box
diagrams can give, already for moderately light charged sleptons, a significant
contribution. As a byproduct we find that the ranges for the angles beta and
gamma in the unitarity triangle are relaxed due to the presence of new
CP-violating phases in K^0 - K^0-bar and B^0_d - B^0_d-bar mixing to 12 degrees
<= beta <= 27 degrees and 20 degrees <= gamma <= 110 degrees.Comment: 36 pages, 27 figures, latex, uses axodraw.st
Supersymmetry and FCNC effects
We consider Flavour Changing Neutral Current processes in the framework of
the supersymmetric extension of the Standard Model. FCNC constraints on the
structure of sfermion mass matrices are reviewed. Furthermore, we analyze
supersymmetric contributions to FCNC transitions which remain in the limit of
flavour-conserving sfermion mass matrices. Implications of the FCNC constraints
on the structure of sfermion mass matrices for SUSY breaking and sfermion mass
generation are discussed. We conclude that the supersymmetric flavour problem
is intriguing but perhaps not as severe as it is commonly believed.Comment: 45 pages, 19 figures, uses epsfig.sty, (axodraw.sty included) To
appear in the Review Volume ``Heavy Flavours II'', eds. A.J. Buras and M.
Lindner, Advanced Series on Directions in High Energy Physics, World
Scientific Publishing Co., Singapore. Revision made on November 19, 1997
amounts to including "note added" concerning bounds on delta_LR from
charginos, and a few correlated minor changes. Misprint in eq. (A.5)
correcte
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