34 research outputs found
Constraints on Higher-Order Perturbative Corrections in Semileptonic Decays from Residual Renormalization-Scale Dependence
The constraint of a progressive decrease in residual renormalization scale
dependence with increasing loop order is developed as a method for obtaining
bounds on unknown higher-order perturbative corrections to
renormalization-group invariant quantities. This technique is applied to the
inclusive semileptonic process (explicitly known to
two-loop order) to obtain bounds on the three- and four-loop perturbative
coefficients that are not accessible via the renormalization group. Using the
principle of minimal sensitivity, an estimate is obtained for the perturbative
contributions to that incorporates
theoretical uncertainty from as-yet-undetermined higher order QCD corrections.Comment: latex2e using amsmath, 8 pages, 4 embedded eps figures. Revised
version contains an additional figure and accompanying revision
Properties of the tensor mesons and
In the mixing framework, the isoscalar
singlet-octet mixing angle for 1 tensor nonet is determined to be the
value of and the decays of the two states are investigated.
Comparing the predicted results of the decays of the two states with the
available experimental data, we find that the predicted results are in good
agreement with the experimental data, which shows that the and
wave functions don't need other components such as glueballs
or the 2 ,3 ,....Comment: revtex 11 pages, 1 eps figure, one reference added, typo correcte
Simple predictions from ALCOR_c for rehadronisation of charmed quark matter
We study the production of charmed hadrons with the help of ALCOR_c, the
algebraic coalescence model for rehadronisation of charmed quark matter.
Mesonic ratios are introduced as factors connecting various antibaryon to
baryon ratios. The resulting simple relations could serve as tests of quark
matter formation and coalescence type rehadronization in heavy ion collisions.Comment: 7 pages in Latex, 1 PS figur
Uncertainties on parton distribution functions from the ZEUS NLO QCD fit to data on deep inelastic scattering
An NLO QCD analysis of the ZEUS data on deep inelastic scattering
together with fixed-target data has been performed from which the gluon and
quark densities of the proton and the value of the strong coupling parameter,
, have been extracted. The study includes a full treatment of
the experimental systematic uncertainties, including point-to-point
correlations. Different ways of incorporating correlated systematic
uncertainties into the fit are discussed and compared.Comment: 8 pages, 1 figure. Invited talk at the Conference on Advanced
Statistical Techniques in Particle Physics, March 18-22 2002, Durham, U
Triple-Product Correlations in B -> V1 V2$ Decays and New Physics
In this paper we examine T-violating triple-product correlations (TP's) in B
-> V1 V2 decays. TP's are excellent probes of physics beyond the standard model
(SM) for two reasons: (i) within the SM, most TP's are expected to be tiny, and
(ii) unlike direct CP asymmetries, TP's are not suppressed by the small strong
phases which are expected in B decays. TP's are obtained via the angular
analysis of B -> V1 V2. In a general analysis based on factorization, we
demonstrate that the most promising decays for measuring TP's in the SM involve
excited final-state vector mesons, and we provide estimates of such TP's. We
find that there are only a handful of decays in which large TP's are possible,
and the size of these TP's depends strongly on the size of nonfactorizable
effects. We show that TP's which vanish in the SM can be very large in models
with new physics. The measurement of a nonzero TP asymmetry in a decay where
none is expected would specifically point to new physics involving large
couplings to the right-handed b-quark.Comment: 42 pages, LaTeX, no figures. Title changed, several explanatory
paragraphs added, references added, analysis and conclusions unchange
Could One Find Petroleum Using Neutrino Oscillations in Matter?
In neutrino physics, it is now widely believed that neutrino oscillations are
influenced by the presence of matter, modifying the energy spectrum produced by
a neutrino beam traversing the Earth. Here, we will discuss the reverse
problem, i.e. what could be learned about the Earth's interior from a single
neutrino baseline energy spectrum, especially about the Earth's mantle. We will
use a statistical analysis with a low-energy neutrino beam under very
optimistic assumptions. At the end, we will note that it is hard to find
petroleum with such a method, though it is not too far away from technical
feasibility.Comment: 6 pages, 4 figures, EPL LaTeX. Final version to be published in
Europhys. Let
The High E_T Drop of J/psi to Drell-Yan Ratio from the Statistical c anti-c Coalescence Model
The dependence of the J/psi yield on the transverse energy E_T in heavy ion
collisions is considered within the statistical c anti-c coalescence model. The
model fits the NA50 data for Pb+Pb collisions at the CERN SPS even in the
high-E_T region (E_T > 100 GeV). Here E_T-fluctuations and E_T-losses in the
dimuon event sample naturally create the celebrated drop in the J/psi to
Drell-Yan ratio.Comment: 14 pages, REVTeX, 1 PS-figure. v2: References are corrected and
update
The process in topcolor-assisted technicolor models
In the context of topcolor-assisted technicolor (TC2) models, we consider the
process and calculate the cross section of
this process at leading order.It is shown that the extra U(1) gauge boson
predicted by TC2 models can give significant contributions to the
process , which may be detected
in the future high energy linear collider(LC) experiments.Comment: latex files,9 pages, 3 figure
phi puzzle in heavy-ion collisions at 2 AGeV: how many K-from phi decays?
The preliminary experimental data on production in the reaction
Ni(1.93 AGeV) + Ni point to a puzzling high yield which can not be
reproduced with present transport codes. We survey the experimental situation
and present prospects for dedicated measurements of the multiplicities
with the and channels at HADES and FOPI.Comment: talk at Strange Quarks in Matter 2001, Frankfurt Sep. 24 - 29, 200
SU(3) Mixing for Excited Mesons
The SU(3)-flavor symmetry breaking and the quark-antiquark annihilation
mechanism are taken into account for describing the singlet-octet mixing for
several nonets assigned by Particle Data Group(PDG). This task is approached
with the mass matrix formalism