1,166 research outputs found
Quark-Antiquark Potential and Generalized Borel Transform
The heavy quark potential and particularly the one proposed by Richardson to
incorporate both asymptotic freedom and linear confinement is analyzed in terms
of a generalized Borel Transform recently proposed. We were able to obtain, in
the range of physical interest, an approximate analytical expression for the
potential in coordinate space valid even for intermediate distances. The
deviation between our approximate potential and the numerical evaluation of the
Richardson's one is much smaller than of QCD. The
and quarkonia energy levels agree reasonably well with
experimental data for and masses in good agreement with the values
obtained from experiments.Comment: 9 pages, 3 Tabl
On measuring alpha in B(t)-> rho^\pm pi^\mp
Defining a most economical parametrization of time-dependent B-> rho^\pm
pi^\mp decays, including a measurable phase alpha_{eff} which equals the weak
phase alpha in the limit of vanishing penguin amplitudes, we propose two ways
for determining alpha in this processes. We explain the limitation of one
method, assuming only that two relevant tree amplitudes factorize and that
their relative strong phase, delta_t, is negligible. The other method, based on
broken flavor SU(3), permits a determination of alpha in B^0-> rho^\pm pi^\mp
in an overconstrained system using also rate measurements of B^{0,+}-> K^* pi
and B^{0,+}->rho K. Current data are shown to restrict two ratios of penguin
and tree amplitudes, r_\pm, to a narrow range around 0.2, and to imply an upper
bound |alpha_{eff} - alpha| < 15 degrees. Assuming that delta_t is much smaller
than 90 degrees, we find alpha =(93\pm 16) degrees and (102 \pm 20) degrees
using BABAR and BELLE results for B(t)-> rho^\pm pi^mp. Avoiding this
assumption for completeness, we demonstrate the reduction of discrete
ambiguities in alpha with increased statistics, and show that SU(3) breaking
effects are effectively second order in r_\pm.Comment: 23 pages, 2 figures, data and references updated, to be published in
Phys. Rev.
B meson light-cone wavefunctions in the heavy quark limit
We present a systematic study of the B meson light-cone wavefunctions in QCD
in the heavy-quark limit. We construct model-independent formulae for the
light-cone wavefunctions in terms of independent dynamical degrees of freedom,
which exactly satisfy the QCD equations of motion and constraints from
heavy-quark symmetry. The results demonstrate novel behaviors of longitudinal
as well as transverse momentum distribution in the B mesons.Comment: 5 pages LaTeX, 1 style file. Talk presented at RADCOR/Loops and Legs
2002, Kloster Banz, Germany, September 8-13, 200
Soft-Collinear Messengers: A New Mode in Soft-Collinear Effective Theory
It is argued that soft-collinear effective theory for processes involving
both soft and collinear partons, such as exclusive B-meson decays, should
include a new mode in addition to soft and collinear fields. These
"soft-collinear messengers" can interact with both soft and collinear particles
without taking them far off-shell. They thus can communicate between the soft
and collinear sectors of the theory. The relevance of the new mode is
demonstrated with an explicit example, and the formalism incorporating the
corresponding quark and gluon fields into the effective Lagrangian is
developed.Comment: 22 pages, 5 figures. Extended Section 6, clarifying the relevance of
different types of soft-collinear interaction
A proof of factorization for B -> D pi
We prove that the matrix elements of four fermion operators mediating the
decay B^0 -> D^+ \pi^- and B^- -> D^0 \pi^- factor into the product of a form
factor describing the B -> D transition and a convolution of a short distance
coefficient with the nonperturbative pion light-cone wave function. This is
shown to all orders in alpha_s, up to corrections suppressed by factors of
1/mb, 1/mc, and 1/E_pi. It is not necessary to assume that the pion state is
dominated by the q-qbar Fock state.Comment: 4 pages, 3 figs, PRL versio
Radiative B decays to the axial mesons at next-to-leading order
We calculate the branching ratios of at next-to-leading
order (NLO) of where is the orbitally excited axial vector
meson. The NLO decay amplitude is divided into the vertex correction and the
hard spectator interaction part. The one is proportional to the weak form
factor of transition while the other is a convolution between
light-cone distribution amplitudes and hard scattering kernel. Using the
light-cone sum rule results for the form factor, we have \calB(B^0\to
K_1^0(1270)\gamma)=(0.828\pm0.335)\times 10^{-5} and \calB(B^0\to
K_1^0(1400)\gamma)=(0.393\pm0.151)\times 10^{-5}.Comment: 17pages, 4 figures. Minor changes, typos corrected. PRD accepted
versio
Convergence of the expansion of the Laplace-Borel integral in perturbative QCD improved by conformal mapping
The optimal conformal mapping of the Borel plane was recently used to
accelerate the convergence of the perturbation expansions in QCD. In this work
we discuss the relevance of the method for the calculation of the Laplace-Borel
integral expressing formally the QCD Green functions. We define an optimal
expansion of the Laplace-Borel integral in the principal value prescription and
establish conditions under which the expansion is convergent.Comment: 10 pages, no figure
Polarization of Upsilon(nS) at the Tevatron
The polarization of inclusive Upsilon(nS) at the Fermilab Tevatron is
calculated within the nonrelativistic QCD factorization framework. We use a
recent determination of the NRQCD matrix elements from fitting the CDF data on
bottomonium production from Run IB of the Tevatron. The result for the
polarization of Upsilon(1S) integrated over the transverse momentum bin 8 < p_T
< 20 GeV is consistent with a recent measurement by the CDF Collaboration. The
transverse polarization of Upsilon(1S) is predicted to increase steadily for
p_T greater than about 10 GeV. The Upsilon(2S) and Upsilon(3S) are predicted to
have significantly larger transverse polarizations than Upsilon(1S).Comment: 15 pages, 3 figure
Puzzles in physics
I discuss some puzzles observed in exclusive meson decays, concentrating
on the large difference between the direct CP asymmetries in the and modes, the large
branching ratio, and the large deviation of the mixing-induced CP asymmetries
in the penguins from those in the trees.Comment: 6 pages, 1 figure, talk presented at the 9th Workshop on High Energy
Physics Phenomenology, Bhubaneswar, Orissa, India, Jan. 3-14, 2006; reference
adde
Quarkonia and the Pole Mass
The pole mass of a heavy quark is ambiguous by an amount of order
. We show that the heavy-quark potential, , is similarly
ambiguous, but that the total static energy, , is unambiguous
when expressed in terms of a short-distance mass. This implies that the
extraction of a short-distance mass from the quarkonium spectrum is free of an
ambiguity of order , in contrast with the pole mass.Comment: 6 pages, LateX. Minor revisions for publicatio
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