13,851 research outputs found
Quasi-two-body decays in the perturbative QCD approach
In this paper, we calculated the branching ratios of the quasi-two-body
decays
by employing the perturbative QCD (PQCD) approach. The contributions from the
-wave resonances , and were taken into
account. The two-pion distribution amplitude is
parameterized by the vector current time-like form factor to study
the considered decay modes. We found that (a) the PQCD predictions for the
branching ratios of the considered quasi-two-body decays are in the order of
, while the two-body decay rates are extracted from those for the
corresponding quasi-two-body decays; (b) the whole pattern of the pion form
factor-squared measured by the BABAR Collaboration could be
understood based on our theoretical results; (c) the general expectation based
on the similarity between and
decays are confirmed: is consistent with the measured
within errors; and (d) new ratios
and among the branching ratios of the
considered decay modes are defined and could be tested by future experiments.Comment: 10 pages, 3 figure
Quasi-two-body decays in the perturbative QCD approach
We study the quasi-two-body decays by employing
the perturbative QCD approach. The two-meson distribution amplitudes
\Phi_{K\pi}^{\text{P-wave}} are adopted to describe the final state
interactions of the kaon-pion pair in the resonance region. The resonance line
shape for the -wave component in the time-like form factor
is parameterized by the relativistic Breit-Wigner function. For
most considered decay modes, the theoretical predictions for their branching
ratios are consistent with currently available experimental measurements within
errors. We also disscuss some ratios of the branching fractions of the
concerned decay processes. More precise data from LHCb and Belle-II are
expected to test our predictions.Comment: 10 pages, 3 figures and 2 tables.To be published in EPJ
Flavor Asymmetry of Nucleon Sea from Detailed Balance
In this study, the proton is taken as an ensemble of quark-gluon Fock states.
Using the principle of detailed balance, we find , which is in surprisingly agreement with the experimental observation.Comment: 4 pages and no figures. Talk presented at the Third
Circum-Pan-Pacific Symposium on "High Energy Spin Physics", Oct. 8-13, 2001,
Beijing, Chin
Data Poisoning Attacks in Contextual Bandits
We study offline data poisoning attacks in contextual bandits, a class of
reinforcement learning problems with important applications in online
recommendation and adaptive medical treatment, among others. We provide a
general attack framework based on convex optimization and show that by slightly
manipulating rewards in the data, an attacker can force the bandit algorithm to
pull a target arm for a target contextual vector. The target arm and target
contextual vector are both chosen by the attacker. That is, the attacker can
hijack the behavior of a contextual bandit. We also investigate the feasibility
and the side effects of such attacks, and identify future directions for
defense. Experiments on both synthetic and real-world data demonstrate the
efficiency of the attack algorithm.Comment: GameSec 201
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