51,519 research outputs found

### Role of Large Gluonic Excitation Energy for Narrow Width of Penta-Quark Baryons in QCD String Theory

We study the narrow decay width of low-lying penta-quark baryons in the QCD
string theoryin terms of gluonic excitations. In the QCD string theory, the
penta-quark baryon decays via a gluonic-excited state of a baryon and meson
system, where a pair of Y-shaped junction and anti-junction is created. Since
lattice QCD shows that the lowest gluonic-excitation energy takes a large value
of about 1 GeV, the decay of the penta-quark baryon near the threshold is
considered as a quantum tunneling process via a highly-excited state (a
gluonic-excited state) in the QCD string theory. This mechanism strongly
suppresses the decay and leads to an extremely narrow decay width of the
penta-quark system.Comment: Talk given at International Conference on the Structure of Baryons
(Baryons 04) October 25 - 29, 2004, Ecole Polytechnique, Palaiseau, Franc

### A New Current Regularization of Thirring Model

We study an ambiguity of the current regularization in the Thirring model. We
find a new current definition which enables to make a comprehensive treatment
of the current. Our formulation is simpler than Klaiber's formulation. We
compare our result with other formulations and find a very good agreement with
their result. We also obtain the Schwinger term and the general formula for any
current regularization.Comment: 7 pages, some comments and references added, to appear in Prog.
Theor. Phy

### Bound States of (Anti-)Scalar-Quarks in SU(3)_c Lattice QCD

Light scalar-quarks \phi (colored scalar particles or idealized diquarks) and
their color-singlet hadronic states are studied with quenched SU(3)_c lattice
QCD in terms of mass generation. We investigate ``scalar-quark mesons''
\phi^\dagger \phi and ``scalar-quark baryons'' \phi\phi\phi as the bound states
of scalar-quarks \phi. We also investigate the bound states of scalar-quarks
\phi and quarks \psi, i.e., \phi^\dagger \psi, \psi\psi\phi and \phi\phi\psi,
which we name ``chimera hadrons''. All the new-type hadrons including \phi are
found to have a large mass due to large quantum corrections by gluons, even for
zero bare scalar-quark mass m_\phi=0 at a^{-1}\sim 1{\rm GeV}. We conjecture
that all colored particles generally acquire a large effective mass due to
dressed gluon effects.Comment: Talk given at The 17th International Spin Physics Symposium
(SPIN2006), Kyoto, Japan, 2-7 Oct 200

### Universal low-temperature properties of quantum and classical ferromagnetic chains

We identify the critical theory controlling the universal, low temperature,
macroscopic properties of both quantum and classical ferromagnetic chains. The
theory is the quantum mechanics of a single rotor. The mapping leads to an
efficient method for computing scaling functions to high accuracy.Comment: 4 pages, 2 tables and 3 Postscript figure

### An Improved Search Method for Gravitational Ringing of Black Holes

A black hole has characteristic quasi-normal modes that will be excited when
it is formed or when the geometry is perturbed. The state of a black hole when
the quasi-normal modes are excited is called the gravitational ringing, and
detections of it will be a direct confirmation of the existence of black holes.
To detect it, a method based on matched filtering needs to be developed.
Generically, matched filtering requires a large number of templates, because
one has to ensure a proper match of a real gravitational wave with one of
template waveforms to keep the detection efficiency as high as possible. On the
other hand, the number of templates must be kept as small as possible under
limited computational costs. In our previous paper, assuming that the
gravitational ringing is dominated by the least-damped (fundamental) mode with
the least imaginary part of frequency, we constructed an efficient method for
tiling the template space. However, the dependence of the template space metric
on the initial phase of a wave was not taken into account. This dependence
arises because of an unavoidable mismatch between the parameters of a signal
waveform and those given discretely in the template space. In this paper, we
properly take this dependence into account and present an improved, efficient
search method for gravitational ringing of black holes.Comment: 19 pages, 9 figure

### Candidates for Inflaton in Quiver Gauge Theory

The inflaton necessary to implement the mechanism of inflationary cosmology
has natural candidates in quiver gauge theory. We discuss the dimensionless
coefficients of quartic couplings and enumerate scalars which are singlet under
the low-energy gauge group. The inflaton mass is generally predicted to be in
the TeV region, close to 4 TeV for one specific unified model. A quartic
inflaton potential, and a mutated hybrid inflation, are discussed. They can
give adequate inflation and appropriate fluctuations but different spectral
indices.Comment: LaTeX 10 page

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### Hypoxic training increases maximal oxygen consumption in Thoroughbred horses well-trained in normoxia.

Hypoxic training is effective for improving athletic performance in humans. It increases maximal oxygen consumption (VÌ‡O2max) more than normoxic training in untrained horses. However, the effects of hypoxic training on well-trained horses are unclear. We measured the effects of hypoxic training on VÌ‡O2max of 5 well-trained horses in which VÌ‡O2max had not increased over 3 consecutive weeks of supramaximal treadmill training in normoxia which was performed twice a week. The horses trained with hypoxia (15% inspired O2) twice a week. Cardiorespiratory valuables were analyzed with analysis of variance between before and after 3 weeks of hypoxic training. Mass-specific VÌ‡O2max increased after 3 weeks of hypoxic training (178 Â± 10 vs. 194 Â± 12.3 ml O2 (STPD)/(kg Ã— min), P<0.05) even though all-out training in normoxia had not increased VÌ‡O2max. Absolute VÌ‡O2max also increased after hypoxic training (86.6 Â± 6.2 vs. 93.6 Â± 6.6 l O2 (STPD)/min, P<0.05). Total running distance after hypoxic training increased 12% compared to that before hypoxic training; however, the difference was not significant. There were no significant differences between pre- and post-hypoxic training for end-run plasma lactate concentrations or packed cell volumes. Hypoxic training may increase VÌ‡O2max even though it is not increased by normoxic training in well-trained horses, at least for the durations of time evaluated in this study. Training while breathing hypoxic gas may have the potential to enhance normoxic performance of Thoroughbred horses

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