49 research outputs found
Tau Polarization in and
We discuss the longitudinal and transverse -polarization in inclusive
decays of hadrons containing -quarks. The calculation is performed by means
of an OPE in HQET. Some mathematical difficulties in calculating transverse
polarizations are explained. Numerical results are presented for longitudinal
and for transverse polarizations, both in and perpendicular to the decay plane.Comment: LATEX, 20 pages, 5 Postscript figure
Inclusive Semileptonic Decays in QCD Including Lepton Mass Effects
Starting from an Operator Product Expansion in the Heavy Quark Effective
Theory up to order 1/m_b^2 we calculate the inclusive semileptonic decays of
unpolarized bottom hadrons including lepton mass effects. We calculate the
differential decay spectra d\Gamma/(dE_\tau ), and the total decay rate for B
meson decays to final states containing a \tau lepton.Comment: 16 pages + 4 figs. appended in uuencoded form, LaTeX, MZ-TH/93-3
Nonperturbative Corrections to the Heavy Lepton Energy Distribution in the Inclusive Decays H_b\ra \tau\bar\nu X.
Nonperturbative corrections up to to the heavy lepton energy
distributions are investigated in the inclusive semileptonic weak decays of
heavy flavors in QCD. In the case of -meson decays, for b \ra u\tau\bnu
transitions they decrease the decay rate by 6\% of its perturbative value,
while for b \ra c\tau\bnu they decrease it by 10\%.Comment: LaTeX, 10 pages, 4 postscript figures included. Few typos correcte
Phenomenology of V_ub from Ratios of Inclusive B Decay Rates
We explore the theoretical feasibility of extracting V_ub from two ratios
built from B meson inclusive partial decays,
R_1 = Gamma(b-> u cbar s)/3Gamma(b -> c l nu), and
R_2 = [Gamma(b -> c X) - Gamma(b -> cbar X)]/Gamma(b -> c ubar d).
We discuss contributions to these quantities from perturbative and
nonperturbative physics, and show that they can be computed with overall
uncertainties at the level of 10%.Comment: 19 pages, 8 embedded EPS figures, uses REVTe
QCD Corrections and the Endpoint of the Lepton Spectrum in Semileptonic B Decays
Recently, Neubert has suggested that a certain class of nonperturbative
corrections dominates the shape of the electron spectrum in the endpoint region
of semileptonic decay. Perturbative QCD corrections are important in the
endpoint region. We study the effects of these corrections on Neubert's
proposal. The connection between the endpoint of the electron spectrum in
semileptonic decay and the photon spectrum in is
outlined.Comment: 18 pages, uses REVTeX, UCSD/PTH 93-38, CALT-68-1910, JHU-TIPAC-930029
(some changes to the discussion of subleading radiative corrections, and
minor typos fixed
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
The Meson Lifetime
We investigate the total inclusive decay rate of the (ground state)
meson within the framework of an operator product expansion in inverse powers
of the heavy quark masses and subsequent matching onto nonrelativistic QCD. The
expansion is organized as a series in the strong coupling and in powers of the
heavy quark velocities in the , reflecting the nonrelativistic nature of a
heavy-heavy bound state. In this aspect the character of the expansion differs
from the more familiar case of heavy-light mesons. The framework incorporates
systematically corrections to the leading - and -quark decays due to
binding effects, as well as contributions from weak annihilation and Pauli
interference. Based on this approach we find for the meson lifetime
ps, the dominant mechanism being the decay of the
charm constituent.Comment: 18 pages, revtex, 2 figures as uudecoded fil
Phenomenology of the Expansion in Inclusive and Meson Decays
We apply a recent theoretical analysis of hadronic observables in inclusive
semileptonic heavy hadron decays to the phenomenology of and mesons.
Correlated bounds on the nonperturbative parameters and
are derived by considering data from decays and, independently,
data from decays. The two sets of bounds are found to be consistent with
each other. The data from decays are then are used to extract a lower limit
on the CKM matrix element . We address the issue of the convergence
of the perturbative expansions used in the analysis, and compare our bounds on
and to lattice and QCD sum rule results. Finally, we
argue that a comparison of the analyses of and decays provides
evidence for the applicability of parton-hadron duality in the semileptonic
decay of charmed hadrons.Comment: 18 pages, 3 embedded figures, uses REVTeX and epsf.sty; this is the
slightly revised version to appear in Physical Review
Higher Order QCD Corrections to
We calculate the corrections to the decay
rate . For reasonable values of this term is
of the same order as both the one-loop and \CO(\alpha_s^2 \log^2 m_W/m_b)
corrections to the decay rate. For the \CO(\alpha_s^2\beta_0)
corrections enhance the rate by . We also discuss the
\CO(\alpha_s^2\beta_0) corrections to , the semileptonic
branching fraction and the charm multiplicity.Comment: LaTex, 14 pages, 2 eps figures. Added one reference, changed some
comment