730 research outputs found
Two-loop QCD corrections to semileptonic b decays at maximal recoil
We present a complete correction to the differential width of
the inclusive semileptonic decay at the kinematical point of
vanishing invariant mass of the leptons, . Together with the recently
computed correction at the upper boundary of the lepton
invariant mass spectrum, this new information permits an estimate of the
effect in the total inclusive semileptonic decay width . We argue that the non-BLM part of the correction
gives at most 1% correction to the inclusive semileptonic decay width . This significantly improves the credibility of extracting
from the inclusive semileptonic decays of the b-hadrons.Comment: 8 pages, revte
Three-loop QCD corrections and b-quark decays
We present three-loop (NNNLO) corrections to the heavy-to-heavy quark
transitions in the limit of equal initial and final quark masses. In analogy
with the previously found NNLO corrections, the bulk of the result is due to
the beta_0^2 alpha_s^3 corrections. The remaining genuine three-loop effects
for the semileptonic b --> c decays are estimated to increase the decay
amplitude by 0.2(2)%. The perturbative series for the heavy-heavy axial current
converges very well.Comment: 5 page
An Approximate Method of Calculating Pressures in the Tip Region of a Rectangular Wing of Circular-Arc Section at Supersonic Speeds
No abstract availabl
Non-Abelian Dipole Radiation and the Heavy Quark Expansion
Dipole radiation in QCD is derived to the second order in . A
power-like evolution of the spin-singlet heavy quark operators is obtained to
the same accuracy. In particular, relation between a
short-distance low-scale running heavy quark mass and the \barMS mass is
given. We discuss the properties of the effective QCD coupling \aw(E) which
governs the dipole radiation. This coupling is advantageous for heavy quark
physics.Comment: 12 pages, Late
Second order QCD corrections to inclusive semileptonic b \to Xc l \bar \nu_l decays with massless and massive lepton
We extend previous computations of the second order QCD corrections to
semileptonic b \to c inclusive transitions, to the case where the charged
lepton in the final state is massive. This allows accurate description of b \to
c \tau \bar \nu_\tau decays. We review techniques used in the computation of
O(\alpha_s^2) corrections to inclusive semileptonic b \to c transitions and
present extensive numerical studies of O(\alpha_s^2) QCD corrections to b \to c
l \bar \nu_l decays, for l =e, \tau.Comment: 30 pages, 4 figures, 5 table
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