18,318 research outputs found
Branching Ratios for the Decay of
Based on measurements the branching ratios for the decay of the recently
discovered dibaryon resonance into two-pion production channels and
into the channel are evaluated. Possibilities for a decay into the
isoscalar single-pion channel are discussed. Finally also the electromagnetic
decay of is considered
Examination of the Nature of the ABC Effect
Recently it has been shown by exclusive and kinematically complete
experiments that the appearance of a narrow resonance structure in
double-pionic fusion reactions is strictly correlated with the appearance of
the so-called ABC effect, which denotes a pronounced low-mass enhancement in
the -invariant mass spectrum. Whereas the resonance structure got its
explanation by the dibaryonic resonance, a satisfactory explanation
for the ABC effect is still pending. In this paper we discuss possible
explanations of the ABC effect and their consequences for the internal
structure of the dibaryon
Quasiparticle Berry curvature and Chern numbers in spin-orbit coupled bosonic Mott insulators
We study the ground-state topology and quasiparticle properties in bosonic
Mott insulators with two- dimensional spin-orbit couplings in cold atomic
optical lattices. We show that the many-body Chern and spin-Chern number can be
expressed as an integral of the quasihole Berry curvatures over the Brillouin
zone. Using a strong-coupling perturbation theory, for an experimentally
feasible spin-orbit coupling, we compute the Berry curvature and the spin Chern
number and find that these quantities can be generated purely by interactions.
We also compute the quasiparticle dispersions, spectral weights, and the
quasimomentum space distribution of particle and spin density, which can be
accessed in cold-atom experiments and used to deduce the Berry curvature and
Chern numbers
Performance Dynamics and Termination Errors in Reinforcement Learning: A Unifying Perspective
In reinforcement learning, a decision needs to be made at some point as to
whether it is worthwhile to carry on with the learning process or to terminate
it. In many such situations, stochastic elements are often present which govern
the occurrence of rewards, with the sequential occurrences of positive rewards
randomly interleaved with negative rewards. For most practical learners, the
learning is considered useful if the number of positive rewards always exceeds
the negative ones. A situation that often calls for learning termination is
when the number of negative rewards exceeds the number of positive rewards.
However, while this seems reasonable, the error of premature termination,
whereby termination is enacted along with the conclusion of learning failure
despite the positive rewards eventually far outnumber the negative ones, can be
significant. In this paper, using combinatorial analysis we study the error
probability in wrongly terminating a reinforcement learning activity which
undermines the effectiveness of an optimal policy, and we show that the
resultant error can be quite high. Whilst we demonstrate mathematically that
such errors can never be eliminated, we propose some practical mechanisms that
can effectively reduce such errors. Simulation experiments have been carried
out, the results of which are in close agreement with our theoretical findings.Comment: Short Paper in AIKE 201
Novel Six-Quark Hidden-Color Dibaryon States in QCD
The recent observation of a hadronic resonance in the proton-neutron
system with isospin and spin-parity raises the possibility
of producing other novel six-quark dibaryon configurations allowed by QCD. A
dramatic example of an exotic six-quark color-singlet system is the charge
, isospin I=3, state which couples strongly to
+ The width and decay properties of such
six-quark resonances could be regarded as manifestations of "hidden-color"
six-quark configurations, a first-principle prediction of QCD -- SU(3)-color
gauge theory for the deuteron distribution amplitude. Other implications and
possible future experiments are discussed
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