23,615 research outputs found
Perspectives on Nuclear Structure and Scattering with the Ab Initio No-Core Shell Model
Nuclear structure and reaction theory are undergoing a major renaissance with
advances in many-body methods, strong interactions with greatly improved links
to Quantum Chromodynamics (QCD), the advent of high performance computing, and
improved computational algorithms. Predictive power, with well-quantified
uncertainty, is emerging from non-perturbative approaches along with the
potential for new discoveries such as predicting nuclear phenomena before they
are measured. We present an overview of some recent developments and discuss
challenges that lie ahead. Our focus is on explorations of alternative
truncation schemes in the harmonic oscillator basis, of which our
Japanese--United States collaborative work on the No-Core Monte-Carlo Shell
Model is an example. Collaborations with Professor Takaharu Otsuka and his
group have been instrumental in these developments.Comment: 8 pages, 5 figures, accepted for publication in Proceedings of
Perspectives of the Physics of Nuclear Structure, JPS Conference Proceedings,
Japan (to appear
Exponents of 2-multiarrangements and multiplicity lattices
We introduce a concept of multiplicity lattices of 2-multiarrangements,
determine the combinatorics and geometry of that lattice, and give a criterion
and method to construct a basis for derivation modules effectively.Comment: 14 page
Stabilities of generalized entropies
The generalized entropic measure, which is optimized by a given arbitrary
distribution under the constraints on normalization of the distribution and the
finite ordinary expectation value of a physical random quantity, is considered
and its Lesche stability property (that is different from thermodynamic
stability) is examined. A general condition, under which the generalized
entropy becomes stable, is derived. Examples known in the literature, including
the entropy for the stretched-exponential distribution, the quantum-group
entropy, and the kappa-entropy are discussed.Comment: 16 pages, no figure
Eliminating the low-mass axigluon window
Using recent collider data, especially on the hadronic width the Z0, we
exclude axigluons in the currently allowed low-mass window, namely axigluons in
the mass range 50 GeV < M_A < 120 GeV. Combined with hadron collider data from
di-jet production, axigluons with masses below roughly 1 TeV are now completely
excluded.Comment: 8 pages, no figures, LaTe
Can a gravitational wave and a magnetic monopole coexist?
We investigate the behavior of small perturbations around the Kaluza-Klein
monopole in the five dimensional space-time. We find that the even parity
gravitational wave does not propagate in the five dimensional space-time with
Kaluza-Klein monopole provided that the gravitational wave is constant in the
fifth direction. We conclude that a gravitational wave and a U(1) magnetic
monopole do not coexist in five dimensional Kaluza-Klein spacetime.Comment: 10 pages, LaTeX. To appear in Modern Physics Letters
The exact radiation-reaction equation for a classical charged particle
An unsolved problem of classical mechanics and classical electrodynamics is
the search of the exact relativistic equations of motion for a classical
charged point-particle subject to the force produced by the action of its EM
self-field. The problem is related to the conjecture that for a classical
charged point-particle there should exist a relativistic equation of motion (RR
equation) which results both non-perturbative, in the sense that it does not
rely on a perturbative expansion on the electromagnetic field generated by the
charged particle and non-asymptotic, i.e., it does not depend on any
infinitesimal parameter. In this paper we intend to propose a novel solution to
this well known problem, and in particular to point out that the RR equation is
necessarily variational. The approach is based on two key elements: 1) the
adoption of the relativistic hybrid synchronous Hamilton variational principle
recently pointed out (Tessarotto et al, 2006). Its basic feature is that it can
be expressed in principle in terms of arbitrary "hybrid" variables (i.e.,
generally non-Lagrangian and non-Hamiltonian variables); 2) the variational
treatment of the EM self-field, taking into account the exact particle
dynamics.Comment: Contributed paper at RGD26 (Kyoto, Japan, July 2008
Toward Generalized Entropy Composition with Different q Indices and H-Theorem
An attempt is made to construct composable composite entropy with different
indices of subsystems and address the H-theorem problem of the composite
system. Though the H-theorem does not hold in general situations, it is shown
that some composite entropies do not decrease in time in near-equilibrium
states and factorized states with negligibly weak interaction between the
subsystems.Comment: 25 pages, corrected some typos, to be published in J. Phys. Soc. Ja
Information measures based on Tsallis' entropy and geometric considerations for thermodynamic systems
An analysis of the thermodynamic behavior of quantum systems can be performed
from a geometrical perspective investigating the structure of the state space.
We have developed such an analysis for nonextensive thermostatistical
frameworks, making use of the q-divergence derived from Tsallis' entropy.
Generalized expressions for operator variance and covariance are considered, in
terms of which the fundamental tensor is given.Comment: contribution to 3rd NEXT-SigmaPhi International Conference (August
2005, Kolymbari, Greece
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