15 research outputs found
Chiral Heat Wave and mixing of Magnetic, Vortical and Heat waves in chiral media
We show that a hot rotating fluid of relativistic chiral fermions possesses a
new gapless collective mode associated with coherent propagation of energy
density and chiral density waves along the axis of rotation. This mode, which
we call the Chiral Heat Wave, emerges due to a mixed gauge-gravitational
anomaly. At finite density the Chiral Heat Wave couples to the Chiral Vortical
Wave while in the presence of an external magnetic field it mixes with the
Chiral Magnetic Wave. The coupling of the Chiral Magnetic and Chiral Vortical
Waves is also demonstrated. We find that the coupled waves - which are coherent
fluctuations of the vector, axial and energy currents - have generally
different velocities compared to the velocities of the individual waves.Comment: 33 pages, 6 figures; v2: minor changes, published versio
Universality of Phases in QCD and QCD-like Theories
We argue that the whole or the part of the phase diagrams of QCD and QCD-like
theories should be universal in the large-N_c limit through the orbifold
equivalence. The whole phase diagrams, including the chiral phase transitions
and the BEC-BCS crossover regions, are identical between SU(N_c) QCD at finite
isospin chemical potential and SO(2N_c) and Sp(2N_c) gauge theories at finite
baryon chemical potential. Outside the BEC-BCS crossover region in these
theories, the phase diagrams are also identical to that of SU(N_c) QCD at
finite baryon chemical potential. We give examples of the universality in some
solvable cases: (i) QCD and QCD-like theories at asymptotically high density
where the controlled weak-coupling calculations are possible, (ii) chiral
random matrix theories of different universality classes, which are solvable
large-N (large volume) matrix models of QCD. Our results strongly suggest that
the chiral phase transition and the QCD critical point at finite baryon
chemical potential can be studied using sign-free theories, such as QCD at
finite isospin chemical potential, in lattice simulations.Comment: v1: 35 pages, 6 figures; v2: 37 pages, 6 figures, minor improvements,
conclusion unchanged; v3: version published in JHE
Fluctuations of Particle Yield Ratios in Heavy-Ion Collisions
We study the dynamical fluctuations of various particle yield ratios at
different incident energies. Assuming that the particle production yields in
the hydronic final state are due to equilibrium chemical processes
(), the experimental results available so far are compared with the
hadron resonance gas model (HRG) taking into account the limited momentum
acceptance in heavy-ion collisions experiments. Degenerated light and conserved
strange quarks are presumed at all incident energies. At the SPS energies, the
HRG with provides a good description for the measured dynamical
fluctuations in . To reproduce the RHIC results,
should be larger than one. We also studied the dynamical fluctuations
of . It is obvious that the energy-dependence of
these dynamical fluctuations is non-monotonic.Comment: 8 pages, 2 eps figures and 1 tabl
A non-electroneutral model for complex reaction-diffusion systems incorporating species interactions
In this study we develop a general framework for describing reaction-diffusion processes in a multi-component electrolyte in which multiple reactions of different types may occur. Our motivation for this is the need to understand how the interactions between species and processes occurring in a complex electrochemical system. We use the framework to develop a modified Poisson-Nernst-Planck model which accounts for the excluded volume interaction (EVI) and incorporates both electrochemical and chemical reactions. Using this model, we investigate how the EVI influences the reactions and how the reactions influence each other in the contexts of the equilibrium state of a system and of a simple electrochemical device under load. Complex behaviour quickly emerges even in relatively simple systems, and deviations from the predictions of ideal solution theory, together with how they may influence the behaviour of more complex system, are discussed
Taming the pion condensation in QCD at finite baryon density: a numerical test in a random matrix model
In the Monte Carlo study of QCD at finite baryon density based upon the phase reweighting method, the pion condensation in the phase-quenched theory and associated zero-mode prevent us from going to the low-temperature high-density region. We propose a method to circumvent them by a simple modification of the density of state method. We first argue that the standard version of the density of state method, which is invented to solve the overlapping problem, is effective only for a certain ‘good’ class of observables. We then modify it so as to solve the overlap problem for ‘bad’ observables as well. While, in the standard version of the density of state method, we usually constrain an observable we are interested in, we fix a different observable in our new method which has a sharp peak at some particular value characterizing the correct vacuum of the target theory. In the finite-density QCD, such an observable is the pion condensate. The average phase becomes vanishingly small as the value of the pion condensate becomes large, hence it is enough to consider configurations with π+ ≃ 0, where the zero mode does not appear. We demonstrate an effectiveness of our method by using a toy model (the chiral random matrix theory) which captures the properties of finite-density QCD qualitatively. We also argue how to apply our method to other theories including finite-density QCD. Although the example we study numerically is based on the phase reweighting method, the same idea can be applied to more general reweighting methods and we show how this idea can be applied to find a possible QCD critical point