4,325 research outputs found
Nonleptonic Weak Decays of B to D_s and D mesons
Branching ratios and polarization amplitudes for B decaying to all allowed
pseudoscalar, vector, axial-vector, scalar and tensor combinations of D_s and D
mesons are calculated in the Isgur Scora Grinstein Wise (ISGW) quark model
after assuming factorization. We find good agreement with other models in the
literature and the limited experimental data and make predictions for as yet
unseen decay modes. Lattice QCD results in this area are very limited. We make
phenomenological observations on decays in to D_s(2317) and D_s(2460) and
propose tests for determining the status and mixings of the axial mesons. We
use the same approach to calculate branching ratios and polarization fraction
for decays in to two D type mesons.Comment: 21 pages, 9 figures. v3: updated to reflect changes in published
paper, conclusions unchanged (see source file for details). Added comments on
factorization. v2: experimental data updated, references added, tables of
results added, more on axial D_s mixing, added section on D D decay modes and
typos correcte
Simply Modeling Meson HQET
A simple relativistic model of heavy-quark-light-quark mesons is proposed. In
an expansion in inverse powers of the heavy quark mass we find that all zeroth
and first order heavy quark symmetry relations are satisfied. The main results
are: - the difference between the meson mass and the heavy quark mass plays a
significant role even at zeroth order; - the slope of the Isgur-Wise function
at the zero recoil point is typically less than ; - the first order
correction to the pseudoscalar decay constant is large and negative; - the four
universal functions describing the first order corrections to the semileptonic
decay form factors are small; - these latter corrections are quite insensitive
to the choice of model parameters, and in particular to the effects of
hyperfine mass splitting.Comment: 17 pages, LaTeX, 3 LaTeX figures in separate file, UTPT-92-16. This
is the version published long ago but not previously archive
Second Order Power Corrections in the Heavy Quark Effective Theory I. Formalism and Meson Form Factors
In the heavy quark effective theory, hadronic matrix elements of currents
between two hadrons containing a heavy quark are expanded in inverse powers of
the heavy quark masses, with coefficients that are functions of the kinematic
variable . For the ground state pseudoscalar and vector mesons, this
expansion is constructed at order . A minimal set of universal form
factors is defined in terms of matrix elements of higher dimension operators in
the effective theory. The zero recoil normalization conditions following from
vector current conservation are derived. Several phenomenological applications
of the general results are discussed in detail. It is argued that at zero
recoil the semileptonic decay rates for and receive only small second order corrections, which are unlikely
to exceed the level of a few percent. This supports the usefulness of the heavy
quark expansion for a reliable determination of .Comment: (34 pages, REVTEX, two postscript figures available upon request),
SLAC-PUB-589
Two-loop corrections to the Isgur-Wise function in QCD sum rules
We complete the QCD sum rule analysis of the Isgur Wise form factor
at next-to-leading order in renormalization-group improved
perturbation theory. To this end, the exact result for the two-loop corrections
to the perturbative contribution is derived using the heavy quark effective
theory. Several techniques for the evaluation of two-loop integrals involving
two different types of heavy quark propagators are discussed in detail, among
them the methods of integration by parts and differential equations. The
order- corrections to the Isgur-Wise function turn out to be small
and well under control. At large recoil, they tend to decrease the form factor
by .Comment: 24 pages (REVTEX), 2 figures available upon request, SLAC-PUB-599
QCD Sum Rules Calculation of Heavy Semileptonic Decay
We set up sum rules for heavy lambda decays in a full QCD calculation which
in the heavy quark mass limit incorporates the symmetries of heavy quark
effective theory. For the semileptonic \La_c decay we obtain a reasonable
agreement with experiment. For the \La_b semileptonic decay we find at the
zero recoil point a violation of the heavy quark symmetry of about 20%.Comment: Revised version. Title changed. 11 pages (RevTex), 4 PS figure
Particle simulations of relativistic electron beam injection from spacecraft
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94852/1/jgra16416.pd
Low temperature phase diagram and critical behaviour of the four-state chiral clock model
The low temperature behaviour of the four-state chiral clock () model
is reexamined using a systematic low temperature series expansion of the free
energy. Previously obtained results for the low temperature phases are
corrected and the low temperature phase diagram is derived. In addition, the
phase transition from the modulated region to the high temperature paraphase is
shown to belong to the universality class of the 3d-XY model.Comment: 17 pages in ioplppt style, 3 figure
The Subleading Isgur-Wise Form Factor to Order in QCD Sum Rules
We calculate the contributions arising at order in the QCD sum
rule for the spin-symmetry violating universal function ,
which appears at order in the heavy quark expansion of meson form
factors. In particular, we derive the two-loop perturbative contribution to the
sum rule. Over the kinematic range accessible in
decays, we find that does not exceed the level of , indicating that power corrections induced by the chromo-magnetic operator
in the heavy quark expansion are small.Comment: 12 pages ReVTeX, 3 figures available upon request, SLAC-PUB-6017,
WIS-92/99/Dec-P
An Analytic Formula and an Upper Bound for epsilon'/epsilon in the Standard Model
Using the idea of the penguin box expansion we find an analytic expression
for epsilon'/epsilon in the Standard Model as a function of m_t, m_s(m_c) and
two non-perturbative parameters B_6 and B_8. This formula includes
next-to-leading QCD/QED short distance effects calculated recently by means of
the operator product expansion and renormalization group techniques. We also
derive an analytic expression for the upper bound on epsilon'/epsilon as a
function of |V_cb|, |V_ub/V_cb|, B_K and other relevant parameters. Numerical
examples of the bound are given.Comment: 10 pages with 1 figure appended in PostScript format; MPI preprint
MPI-Ph/93-60 and TU preprint TUM-T31-47/9
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