M. Asakawa

Hadronic spectral functions in lattice QCD

QCD spectral functions of hadrons in the pseudo-scalar and vector channels are extracted from lattice Monte Carlo data of the imaginary time Greens functions. The maximum entropy method works well for this purpose, and the resonance and continuum structures in the spectra are obtained in addition to the ground state peaks.

Squeezed Correlations and Spectra for Mass-Shifted Bosons

Huge back-to-back correlations are shown to arise for thermal ensembles of bosonic states with medium-modified masses. The effect is experimentally observable in high energy heavy ion collisions.

Fluctuation probes of quark deconfinement

The size of the average fluctuations of net baryon number and electric charge in a finite volume of hadronic matter differs widely between the confined and deconfined phases. These differences may be exploited as indicators of the formation of a quark-gluon plasma in relativistic heavy-ion collisions, because fluctuations created in the initial state survive until freeze-out due to the rapid expansion of the hot fireball.

Anomaly induced domain formation of disoriented chiral condensates

We discuss the effect of the chiral anomaly as a possible mechanism for triggering the formation of domains of disoriented chiral condensate (DCC) in relativistic heavy ion collisions. The anomalous {pi}{sup 0}{r_arrow}2{gamma} coupling and the strong, Lorentz contracted electromagnetic fields of the heavy ions combine to produce the {open_quotes}anomaly kick{close_quotes} to the field configuration of the neutral pion field. We implement the effect of the anomaly kick in our numerical simulation of the linear sigma model in a schematic way which preserves its characteristic features: the effect is coherent over a large region of space but is opposite in sign above and below the ion scattering plane. We demonstrate by detailed simulations with longitudinal expansion that the DCC domain formation is dramatically enhanced by the anomaly kick in spite of its small absolute magnitude. We examine the behavior of various physical quantities such as pion fields, the axial vector currents, and their correlation functions. Our results also provide useful insight into the mechanism and properties of DCC domain formation, in general. Finally, we discuss some experimental observables which can signal the anomaly induced formation of DCC. {copyright} {ital 1998} {ital The American Physical Society}

Non-central heavy-ion collisions are the place to look for DCC

Abstract We give two reasons why we believe that non-central ultrarelativistic heavy ion collisions are the place to look for the disoriented chiral condensates (DCC). First, we argue that the most probable quench scenario for the formation of DCC requires non-central collisions. Second, we show by numerical simulations that strong electromagnetic fields of heavy ions can exert a surprisingly large effect on the DCC domain formation through the chiral anomaly. The effect again requires non-central collisions. Interestingly, the result of simulations is consistent with the formation of correlated two domains of the chiral condensate, which are aligned in space, perpendicular to the scattering plane, but misaligned in isospin space.

Analysis of spectral functions in lattice QCD with the maximum entropy method

Abstract QCD spectral functions of hadrons in the pseudo-scalar and vector channels are extracted from lattice Monte Carlo data of the imaginary time Greens functions. The maximum entropy method works well for this purpose, and the resonance and continuum structures in the spectra are obtained in addition to the ground state peaks.

Back-to-back correlations for bosons modified by medium

Abstract Novel back-to-back correlations are shown to arise for thermal ensembles of squeezed bosonic states associated with medium-modified mass-shifts. The strength of these correlations could become unexpectedly large in heavy ion collisions.

How can we see hadron modifications in nuclei

Abstract In this paper, we explain (i) what is hadron modification in medium, (ii) what should be performed to observe it, and (iii) what we should expect to observe.

Spectral functions of hadrons in lattice QCD

Abstract Using the maximum entropy method, spectral functions of the pseudo-scalar and vector mesons are extracted from lattice Monte Carlo data of the imaginary time Greens functions. The resonance and continuum structures as well as the ground state peaks are successfully obtained. Error analysis of the resultant spectral functions is also given on the basis of the Bayes probability theory.

Relativistic heavy ion collisions — Where are we now? Where do we go?

Abstract Various aspects of the current status of ultrarelativistic heavy ion collisions are reviewed. Perspectives of heavy ion physics in the future are given as well.