22 research outputs found
Constraint on scalar leptoquark from low energy leptonic observables
We consider the full flavor structure of the leptoquark model and
derive conservative constraints on the elements of the left- and right-handed
coupling matrices. We focus on the cases where the muon deviation is
explained by muon couplings to the top-quark or to the charm-quark or to all
up-type quarks. The most significant constraints arise from charged lepton
flavor violating decays of the muon and the lepton and from the
conversion process. Kaon decays and perturbativity provide further constraints.
We find strong constraints on almost all coupling matrix elements, implying a
very hierarchical matrix structure, where individual entries must differ by at
least 4 orders of magnitude. The program was used with
appropriate model files incorporating the parameterization of the couplings in
the up-type mass diagonal basis. The expressions for the leptonic observables
were generated and cross-checked with the help of the
extension of the program
Two-Loop Corrections to the Muon Magnetic Moment from Fermion/Sfermion Loops in the MSSM: Detailed Results
Recently, first results were presented for two-loop corrections to the muon
(g-2) from fermion/sfermion loops in the MSSM. These corrections were shown to
be generally large and even logarithmically enhanced for heavy sfermions. Here,
full details of the calculation and analytical results are presented. Also, a
very compact formula is provided which can be easily implemented and serves as
a good approximation of the full result as a function of the fourteen most
important input parameters. Finally, a thorough discussion of the numerical
behaviour of the fermion/sfermion-loop corrections to (g-2)_\mu\ is given. The
discussion includes the case of very heavy SUSY masses as well as
experimentally allowed scenarios with very light SUSY masses.Comment: 56 pages, 20 figures. v2 is the journal version. The Mathematica code
amu2Lapprox.m for the compact approximation formula can be obtained from
http://iktp.tu-dresden.de/?id=theory-softwar