4,924 research outputs found
Search for charmonium and bottomonium states in at B factories
We study the production of charmonium states in at B factories with (n=1,2,3), (m=1,2), and
. In the S and P wave case, contributions of tree-QED with one-loop
QCD corrections are calculated within the framework of nonrelativistic
QCD(NRQCD) and in the D-wave case only the tree-QED contribution are
considered. We find that in most cases the QCD corrections are negative and
moderate, in contrast to the case of double charmonium production , where QCD corrections are positive and large in most cases. We
also find that the production cross sections of some of these states in
are larger than that in by an
order of magnitude even after the negative QCD corrections are included. So we
argue that search for the X(3872), X(3940), Y(3940), and X(4160) in at B factories may be helpful to clarify the nature of these
states. For completeness, the production of bottomonium states in
annihilation is also discussed.Comment: 13pages, 4 figure
Probabilistic Human Mobility Model in Indoor Environment
Understanding human mobility is important for the development of intelligent
mobile service robots as it can provide prior knowledge and predictions of
human distribution for robot-assisted activities. In this paper, we propose a
probabilistic method to model human motion behaviors which is determined by
both internal and external factors in an indoor environment. While the internal
factors are represented by the individual preferences, aims and interests, the
external factors are indicated by the stimulation of the environment. We model
the randomness of human macro-level movement, e.g., the probability of visiting
a specific place and staying time, under the Bayesian framework, considering
the influence of both internal and external variables. We use two case studies
in a shopping mall and in a college student dorm building to show the
effectiveness of our proposed probabilistic human mobility model. Real
surveillance camera data are used to validate the proposed model together with
survey data in the case study of student dorm.Comment: 8 pages, 9 figures, International Joint Conference on Neural Networks
(IJCNN) 201
NRQCD Predictions of D-Wave Quarkonia Decay into Light Hadrons at Order
In this paper, in the framework of NRQCD we study the light hadron (LH)
decays of the spin-triplet (S=1) D-wave heavy quarkonia. The short distance
coefficients of all Fock states in the quarkonia including
D-wave color-singlet, P-wave color-octet and S-wave color-singlet and
color-octet are calculated perturbatively at order. The operator
evolution equations of the four-fermion operators are also derived and are used
to estimate the numerical values of the long distance matrix elements. We find
that for the system, the LH decay widths of predicted
by NRQCD is about times larger than the phenomenological potential
model results, while for the system the two theoretical estimations
of are in coincidence with each other. Our
predictions for LH decay widths are MeV for J=1,2,3; and for ,
KeV for J=1,2,3.Comment: 12 figures, references added, published version in PR
Relativistic corrections to exclusive and inclusive double charm production at B factories
In order to clarify the puzzling problems in double charm production,
relativistic corrections at order to the processes and at B factories are studied
in non-relativistic quantum chromodynamics. The short-distance parts of
production cross sections are calculated perturbatively, while the
long-distance matrix elements are estimated from and decays
up to errors of order . Our results show that the relativistic correction
to the exclusive process is significant, which,
when combined together with the next-to-leading order corrections,
could resolve the large discrepancy between theory and experiment; whereas for
the inclusive process the relativistic
correction is tiny and negligible. The physical reason for the above difference
between exclusive and inclusive processes largely lies in the fact that in the
exclusive process the relative momentum between quarks in charmonium
substantially reduces the virtuality of the gluon that converts into a charm
quark pair, but this is not the case for the inclusive process, in which the
charm quark fragmentation is significant, and QCD radiative
corrections can be more essential.Comment: Version to appear in PRD. In the summary an explicit statement added:
"for the J/\psi eta_c cross section the relativistic correction alone gives
an enhancement factor of 1.7 while the combination of relativistic correction
with QCD radiative correction results in a much larger enhancement factor of
9". One reference added. A few typos correcte
Understanding the processes observed by Belle
We calculate the production cross sections for ,
and in annihilation through one virtual photon in the
framework of perturbative QCD with constituent quarks. The calculated cross
sections for and production are roughly in agreement
with the recent Belle data. The helicity decomposition for meson
production is also calculated. The fraction of the final
state in process is found to be 65%. The fraction of
production is 100% and is forbidden in annihilation
through one virtual photon. We further consider annihilation through
two virtual photons, and then find the fraction of in process to be about 91%.Comment: 8 pages, 2 figure
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