31 research outputs found
Testing the left-handedness of the b \to c transition
We analyse the spin structure of inclusive semileptonic b \to c transitions
and the effects of non-standard model couplings on the rates and the spectra.
The calculation includes the {\cal O} (\alpha_s) corrections as well as the
leading non-perturbative ones.Comment: 15 pages, 3 figure
Higher Order Power Corrections in Inclusive B Decays
We discuss order 1/m_b^4 and 1/m_b^5 corrections in inclusive semileptonic
decay of a meson. We identify relevant hadronic matrix elements of
dimension seven and eight and estimate them using the ground-state saturation
approximation. Within this approach the effects on the integrated rate and on
kinematic moments are estimated. The overall relative shift in V_{cb} turns out
about +0.4% as applied to the existing fits. Similar estimates are presented
for B -> X_s+\gamma decays.Comment: 30 pages, 16 figure
Effect of FCNC mediated Z boson on lepton flavor violating decays
We study the three body lepton flavor violating (LFV) decays , and the semileptonic decay in the flavor changing neutral current (FCNC) mediated boson
model. We also calculate the branching ratios for LFV leptonic B decays,
, , and the
conversion of muon to electron in Ti nucleus. The new physics parameter space
is constrained by using the experimental limits on and
. We find that the branching ratios for and processes could be as large as and . For other LFV B decays the branching ratios are found to be too
small to be observed in the near future.Comment: 15 pages, 8 figures, typos corrected, one more section added, version
to appear in EPJ
Search for Lepton Flavor Violating tau Decays into Three Leptons
We search for lepton-flavor-violating tau decays into three leptons (electron
or muon) using 535 fb-1 of data collected with the Belle detector at the KEKB
asymmetric-energy e+e- collider. No evidence for these decays is observed, and
we set 90% confidence level upper limits on the branching fractions of
(2.0-4.1)x10^-8. These results improve upon our previously published upper
limits by factors of 4.9 to 10.Comment: 11 pages, 4 figures, submitted to Phys. Lett.
Search for the lepton flavour violating decay Ï â â ÎŒ â ÎŒ + ÎŒ â
A search for the lepton flavour violating decay
is performed with the LHCb experiment. The data sample corresponds to an
integrated luminosity of of proton-proton collisions at
a centre-of-mass energy of and
at . No evidence is found
for a signal, and a limit is set at confidence level on the branching
fraction, .Comment: 20 pages, 10 figures, published as JHEP 02 (2015) 12