Heavy-light meson in anisotropic lattice QCD

We examine whether the $O(a)$ improved quark action on anisotropic lattices can be used as a framework for the heavy quark, which enables precision computation of matrix elements of heavy-light mesons. To this end, it is crucial to verify that a mass independent and nonperturbative tuning of the parameters is possible. As a first step, we observe the dispersion relation of heavy-light mesons on a quenched lattice using the action which is nonperturbatively tuned only for the leading terms. On a lattice with the spatial cutoff $a_\sigma^{-1} \simeq$ 1.6 GeV and the anisotropy $\xi=4$, the relativity relation holds within 2% accuracy in the quark mass region $a_\sigma m_Q \leq 1.2$ with the bare anisotropy parameter tuned for the massless quark. We also apply the action to a calculation of heavy-light decay constants in the charm quark mass region.Comment: Lattice2002(heavyquark), 3 pages, 2 figure

Comment on ``Confirmation of the Sigma Meson''

We comment on the recent paper by N.A. Tornqvist and M. Roos published in Phys. Rev. Lett. 76, 1575 (1996).Comment: 3 pages (LaTeX), 1 PostScript Figur

Fabrication and Characterization of Metal Carbide-graphite Composites

Hot press fabrication effects on phase equilibrium and physical properties of refractory metal carbide-graphite composite

Charmed hadron physics in quenched anisotropic lattice QCD

We investigate the anisotropic lattice with $O(a)$ improved quark action as a candidate of framework in which we can treat both the heavy and light quark region in the same manner and systematically reduce the systematic uncertainties. To examine applicability of anisotropic lattice, we calculate the charmed meson spectrum and decay constants in quenched approximation. We find consistent result with most advanced results on isotropic lattices.Comment: 3 pages, 1 figure, contribution to Fifth KEK Topical Conference - Frontiers in Flavor Physics -, Tsukuba, Japan, November 20-22, 200

A Parametric Study of the Acoustic Mechanism for Core-Collapse Supernovae

We investigate the criterion for the acoustic mechanism to work successfully in core-collapse supernovae. The acoustic mechanism is an alternative to the neutrino-heating mechanism. It was proposed by Burrows et al., who claimed that acoustic waves emitted by $g$-mode oscillations in proto-neutron stars (PNS) energize a stalled shock wave and eventually induce an explosion. Previous works mainly studied to which extent the $g$-modes are excited in the PNS. In this paper, on the other hand, we investigate how strong the acoustic wave needs to be if it were to revive a stalled shock wave. By adding the acoustic power as a new axis, we draw a critical surface, an extension of the critical curve commonly employed in the context of neutrino heating. We perform both 1D and 2D parametrized simulations, in which we inject acoustic waves from the inner boundary. In order to quantify the power of acoustic waves, we use the extended Myers theory to take neutrino reactions into proper account. We find for the 1D simulations that rather large acoustic powers are required to relaunch the shock wave, since the additional heating provided by the secondary shocks developed from acoustic waves is partially canceled by the neutrino cooling that is also enhanced. In 2D, the required acoustic powers are consistent with those of Burrows et al. Our results seem to imply, however, that it is the sum of neutrino heating and acoustic powers that matters for shock revival.Comment: 20 pages, 19 figures, accepted by Ap

Effective Theory Approach to the Skyrme model and Application to Pentaquarks

The Skyrme model is reconsidered from an effective theory point of view. From the most general chiral Lagrangian up to including terms of order $p^4$, $N_c$ and $\delta m^2$ ($\delta m\equiv m_s-m$), new interactions, which have never been considered before, appear upon collective coordinate quantization. We obtain the parameter set best fitted to the observed low-lying baryon masses, by performing the second order perturbative calculations with respect to $\delta m$. We calculate the masses and the decay widths of the other members of (mainly) anti-decuplet pentaquark states. The formula for the decay widths is reconsidered and its baryon mass dependence is clarified.Comment: 65 pages, 1 figure. Revised version:the complete second order perturbative calculations performed and two appendices adde

Conformal Phase Transition and Fate of the Hidden Local Symmetry in Large N_f QCD

It is observed that the Hidden Local Symmetry (HLS) for the vector mesons in the ordinary QCD with smaller N_f plays the role of the "Higgsed magnetic gauge symmetry" for the Seiberg duality in the SUSY QCD. For large N_f where the conformal phase transition with chiral restoration and deconfinement is expected to take place, we find that the HLS model also exhibits the chiral restoration by the loop corrections (including the quadratic divergence) in a manner similar to that in the CP^{N-1} model, provided that the bare HLS Lagrangian respects the Georgi's vector limit at a certain N_f (\approx 7).Comment: 4 Pages (RevTeX), 3 PS figures are included Minor corrections are made for the introductory part. This is the version to appear in Physical Review Letter

Vector Manifestation and Fate of Vector Mesons in Dense Matter

We describe in-medium properties of hadrons in dense matter near chiral restoration using a Wilsonian matching to QCD of an effective field theory with hidden local symmetry at the chiral cutoff $\Lambda$. We find that chiral symmetry is restored in vector manifestation \`a la Harada and Yamawaki at a critical matter density $n_c$. We express the critical density in terms of QCD correlators in dense matter at the matching scale. In a manner completely analogous to what happens at the critical $N_f^c$ and at the critical temperature $T^c$, the vector meson mass is found to vanish (in the chiral limit) at chiral restoration. This result provides a support for Brown-Rho scaling predicted a decade ago.Comment: 14 pages, 2 figure