414 research outputs found
Complete resummation of chirally-enhanced loop-effects in the MSSM with non-minimal sources of flavor-violation
In this article we present the complete resummation of the leading
chirally-enhanced corrections stemming from gluino-squark, chargino-sfermion
and neutralino-sfermion loops in the MSSM with non-minimal sources of
flavor-violation. We compute the finite renormalization of fermion masses and
the CKM matrix induced by chirality-flipping self-energies. In the decoupling
limit Msusy>>v, which is an excellent approximation to the full theory, we give
analytic results for the effective gaugino(higgsino)-fermion-sfermion and the
Higgs-fermion-fermion vertices. Using these vertices as effective Feynman
rules, all leading chirally-enhanced corrections can consistently be included
into perturbative calculations of Feynman amplitudes. We also give a
generalized parametrization for the bare CKM matrix which extends the classic
Wolfenstein parametrization to the case of complex parameters lambda and A.Comment: 31 pages, 3 figures; typos correcte
SUSY_FLAVOR v2.5: a computational tool for FCNC and CP-violating processes in the MSSM
We present SUSY_FLAVOR version 2.5 - a Fortran 77 program that calculates
low-energy flavor observables in the general -parity conserving MSSM. For a
set of MSSM parameters as input, the code gives predictions for: 1. Electric
dipole moments of the leptons and the neutron. 2. Anomalous magnetic moments
(i.e. ) of the leptons. 3. Radiative lepton decays ( and
). 4. Rare Kaon decays (
and ). 5. Leptonic decays (,
, and ). 6. Radiative
decays (). 7. Rare decays of top quark to Higgs boson
(). 8. processes (, , and mixing). SUSY_FLAVOR performs the resummation of
all chirally enhanced corrections, i.e. takes into account the effects enhanced
by and/or large trilinear soft mixing terms to all orders in
perturbation theory. All calculations are done using exact diagonalization of
the sfermion mass matrices. Comparing to previous versions, in SUSY_FLAVOR v2.5
parameter initialization in SLHA2 format has been significantly generalized and
simplified, so that program accepts without modifications most of the output
files produced by other codes calculating MSSM spectra and processes. In
addition, the routine calculating branching ratios for rare decays of top quark
to Higgs boson has been included. The program can be obtained from
www.fuw.edu.pl/susy_flavor.Comment: Updated from arXiv:1003.4260 [hep-ph] (SUSY_FLAVOR v1 manual), 61
pages; updated sections on modified user interface and on newly added
processes. SUSY_FLAVOR code available at http://www.fuw.edu.pl/susy_flavo
Natural SUSY and Kaon Mixing in view of recent results from Lattice QCD
Lattice results are available for Delta S=2 matrix elements for the first
time in full QCD, which improve considerably the status of hadronic
uncertainties in K-Kbar mixing with respect to earlier phenomenological
studies. Using an average of the ETMC and RBC results, we analyze epsilonK in
Natural SUSY. This scenario arises as a consistent BSM framework after the
latest results from the LHC. The analysis is improved with respect to previous
studies including next-to-leading order matching conditions of order
(alpha_s)^3. We derive new bounds for SUSY mass insertions in the scenario with
a light third generation and study the implications for squark and gluino
masses, compared with direct searches at the LHC. Assuming natural values for
the flavor violating SUSY couplings of both chiralities, we find that the
sbottom must be heavier than 3 TeV for a gluino mass up to 10 TeV. In this
scenario no natural values for squark and gluino masses can satisfy the flavor
bounds.Comment: v3: Results updated with the latest (September 2012) lattice QCD
results. Version published in Physical Review
Top mass dependent alpha_s^3 corrections to B-meson mixing in the MSSM
We compute the top mass dependent NLO strong interaction matching conditions
to the Delta F=2 effective Hamiltonian in the general MSSM. We study the
relevance of such corrections, comparing its size with that of previously known
NLO corrections in the limit mt->0, in scenarios with degeneracy, alignment,
and hierarchical squarks. We find that, while these corrections are generally
small, there are regions in the parameter space where the contributions to the
Wilson coefficients C1 and C4 could partially overcome the expected suppression
m_t/M_SUSY.Comment: 15 pages, 6 figure
Supersymmetric contributions to and decays in SCET
We study the decay modes and using Soft Collinear Effective Theory. Within Standard Model and
including the error due to the SU(3) breaking effect in the SCET parameters we
find that BR and BR
corresponding to
solution 1 and solution 2 of the SCET parameters respectively.For the decay
mode , we find that BR and BR corresponding to solution 1 and
solution 2 of the SCET parameters respectively. We extend our study to include
supersymmetric models with non-universal A-terms where the dominant
contributions arise from diagrams mediated by gluino and chargino exchanges. We
show that gluino contributions can not lead to an enhancement of the branching
ratios of and . In
addition, we show that SUSY contributions mediated by chargino exchange can
enhance the branching ratio of by about 14% with
respect to the SM prediction. For the branching ratio of , we find that SUSY contributions can enhance its value by about 1% with
respect to the SM prediction.Comment: 25 pages,5 figures, version accepted for publicatio
Hints of R-parity violation in B decays into
In this article we show that the recently observed enhanced semi-leptonic and
leptonic decay rates of the B meson into \tau \nu modes can be explained within
the frame work of R-parity violating (RPV) MSSM. In particular, RPV
contributions involving the exchange of right-handed down-type squarks give a
universal contribution to the B+ --> \tau \nu, B --> D \tau \nu and the B -->
D* \tau \nu decays. We find that the masses and couplings that explain the
enhanced B decay rates are phenomelogically viable and the squarks can possibly
be observed at the LHC.Comment: 8 pages and 3 figures; Updated section 2 and 3, but results are
unmodifie
Lepton flavour violation in the MSSM
We derive new constraints on the quantities delta_{XY}^{ij}, X,Y=L,R, which
parametrise the flavour-off-diagonal terms of the charged slepton mass matrix
in the MSSM. Considering mass and anomalous magnetic moment of the electron we
obtain the bound |delta^{13}_{LL} delta^{13}_{RR}|<0.1 for tan beta=50, which
involves the poorly constrained element delta^{13}_{RR}. We improve the
predictions for the decays tau -> mu gamma, tau -> e gamma and mu -> e gamma by
including two-loop corrections which are enhanced if tan beta is large. The
finite renormalisation of the PMNS matrix from soft SUSY-breaking terms is
derived and applied to the charged-Higgs-lepton vertex. We find that the
experimental bound on BR(tau -> e gamma) severely limits the size of the MSSM
loop correction to the PMNS element U_{e3}, which is important for the proper
interpretation of a future U_{e3} measurement. Subsequently we confront our new
values for delta^{ij}_{LL} with a GUT analysis. Further, we include the effects
of dimension-5 Yukawa terms, which are needed to fix the Yukawa unification of
the first two generations. If universal supersymmetry breaking occurs above the
GUT scale, we find the flavour structure of the dimension-5 Yukawa couplings
tightly constrained by mu -> e gamma.Comment: 37 pages, 15 figures; typo in Equation (35) and (49) correcte
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