The Degrees of Freedom in Hot Quenched QCD

In quenched QCD, on lattices with \nt=4, the absence of a pole in the pseudoscalar meson channel for $T>T_c$ is demonstrated. A set of effective 4-fermi couplings is extracted. It is observed that this coupling is small in the vector channel for all $T>T_c$, but not in the pseudoscalar channel. The temperature dependence of hadronic parameters below \tc{} is found to be small. NOTE: Latex source, no figures, needs espcrc2.sty from hep-lat macros.Comment: 3 pages, HLRZ 92-7

When hot water freezes before cold

I suggest that the origin of the Mpemba effect (the freezing of hot water before cold) is freezing-point depression by solutes, either gaseous or solid, whose solubility decreases with increasing temperature so that they are removed when water is heated. They are concentrated ahead of the freezing front by zone refining in water that has not been heated, reduce the temperature of the freezing front, and thereby reduce the temperature gradient and heat flux, slowing the progress of the front. I present a simple calculation of this effect, and suggest experiments to test this hypothesis.Comment: 7 pages, 1 figur

Calculation of Screening Masses in a Chiral Quark Model

We consider a simple model for the coordinate-space vacuum polarization function which is often parametrized in terms of a screening mass. We discuss the circumstances in which the standard result for the screening mass, $m_{sc}=\pi T$, is obtained. In the model considered here, that result is obtained when the momenta in the relevant vacuum polarization integral are small with respect to the first Matsubara frequency.Comment: 6 pages, 2 figure

Properties of Hadrons in the Nuclear Medium

This review is devoted to the discussion of hadron properties in the nuclear medium and its relation to the partial restoration of chiral symmetry. Special attention is given to disentangle in-medium effects due to conventional many-body interactions from those due to the change of the chiral condensate. In particular, we shall discuss medium effects on the Goldstone bosons (pion, kaon and eta), the vector mesons (rho, omega, phi), and the nucleon. Also, for each proposed in-medium effect the experimental consequence and results will be reviewed.Comment: 43 pages, 8 figures, uses epsf-style file. To appear in Ann. Rev. Nucl. Part. Sci. Vol 4

The Chiral Phase Transition

I review the current understanding of the chiral phase transition in QCD, with particular emphasis on recent results obtained in the instanton liquid model.Comment: 13 pages, 9 PS figures, to appear in QM96 proceedings (Nucl. Phys. A

What do heavy-light (Qqˉ Q\bar{q} ) quark systems tell us about QCD vacuum properties?

Arguments in favor of a large magnitude ( at least two- three times bigger than its factorized value) of the mixed vacuum condensate \la \bar{q}G_{\mu\nu}^a G_{\mu\nu}^a q \ra are given. The analysis is based on the strict inequalities which follow from the QCD sum rules method and on very plausible phenomenological assumptions like $m_{B_s} > m_{B_u}$ for the few lowest exited $Q\bar{q}$ states in a heavy quark limit $m_Q\rightarrow\infty$. The same arguments show the suppression of the $SU(3)$ symmetry breaking effects for vacuum condensates when the additional gluon fields are included.Comment: SMU-HEP-PH-9323, 18pages, LATE

The heat capacity of nitrogen chains in grooves of single-walled carbon nanotube bundles

The heat capacity of bundles of closed-cap single-walled carbon nanotubes (SWNT) with one-dimensional chains of nitrogen molecules adsorbed in the grooves has been first experimentally studied at temperatures from 2K to 40K using an adiabatic calorimeter. The contribution of nitrogen C(T) to the total heat capacity has been separated. In the region 2-8K the behaviour of the curve C(T) is qualitatively similar to the theoretical prediction of the phonon heat capacity of 1D chains of krypton (Kr) atoms localized in the grooves of SWNT bundles. Below 3K the dependence C(T) is linear. Above 8K the dependence C(T) becomes steeper in comparison with the case of Kr atoms. This behaviour of the heat capacity C(T) is due to the contribution of the rotational degrees of freedom of the nitrogen molecules.Comment: 15 pages, 4 figure

A Variational Solution of the Schrödinger Equation in an Inhomogeneous Central Field

The present work is devoted to the computer modeling of emission processes from the graphene surface which is a promising material for modern applications. We examine the effect of the ion field inhomogeneity on the variational solution of the Schrödinger equation for the ground state of a loosely bound electron of a hydrogen-like carbon atom, which simulates the graphene model. This shows a significant impact of the allowance for the field inhomogeneity to the ground state of the electron

How reliable are the HQET-sum rule predictions?

We test the internal consistencies and the reliability of the existing estimates of the decay constant $f_B$ in the static limit, the meson-quark mass gap $\bar \Lambda$ and the kinetic energy $K$ of a heavy quark obtained from the heavy quark effective theory (HQET)-sum rules. Finite energy local duality sum rules (FESR) have also been used to fix $approximatively$ the value of the continuum energy and to study the correlations among these different parameters. Then, we deduce to two-loop accuracy: \bl=(0.65\pm 0.05) GeV, $K=-(0.5 \pm 0.2)$GeV^2$, implying the value of the pole mass in HQET:$M_b= (4.61 \pm 0.05)$GeV. By combining the results from the sum rules in HQET and in the full theory, we obtain$f_B^\infty=(1.98 \pm 0.31)f_\pi$and the quadratic mass dependence of the pseudoscalar decay constant:$f_P\sqrt{M_P}=(0.33 \pm 0.06)$GeV$^{3/2}\als^{1/\beta_1}2}\als^{1/\beta_1 1-2\als/3\pi-1.1/M_Q +0.7/M_Q^2 .$Comment: PS file, figures available by reques

Oscillations of the static meson fields at finite baryon density

The spatial dependence of static meson correlation functions at finite baryon density is studied in the Nambu -- Jona - Lasinio model. In contrast to the finite temperature case, we find that the correlation functions at finite density are not screened but exhibit long-range oscillations. The observed phenomenon is analogous to the Friedel oscillations in a degenerate electron gas