299 research outputs found
HBT pion interferometry with phenomenological mean field interaction
To extract information on hadron production dynamics in the ultrarelativistic
heavy ion collision, the space-time structure of the hadron source has been
measured using Hanbury Brown and Twiss interferometry. We study the distortion
of the source images due to the effect of a final state interaction. We
describe the interaction, taking place during penetrating through a cloud
formed by evaporating particles, in terms of a one-body mean field potential
localized in the vicinity of the source region. By adopting the semiclassical
method, the modification of the propagation of an emitted particle is examined.
In analogy to the optical model applied to nuclear reactions, our
phenomenological model has an imaginary part of the potential, which describes
the absorption in the cloud. In this work, we focus on the pion interferometry
and mean field interaction obtained using a phenomenological forward
scattering amplitude in the elastic channels. The p-wave scattering with
meson resonance leads to an attractive mean field interaction, and the presence
of the absorptive part is mainly attributed to the formation of this resonance.
We also incorporate a simple time dependence of the potential reflecting the
dynamics of the evaporating source. Using the obtained potential, we examine
how and to what extent the so-called HBT Gaussian radius is varied by the
modification of the propagation
Charge redistribution from novel magneto-vorticity coupling in anomalous hydrodynamics
We discuss new transport phenomena in the presence of both a strong magnetic
field and a vortex field. Their interplay induces a charge distribution and a
current along the magnetic field. We show that the associated transport
coefficients can be obtained from a simple analysis of the single-particle
distribution functions and also from the Kubo formula calculation. The
consistent results from these analyses suggest that the transport coefficients
are tied to the chiral anomaly in the (1+1) dimension because of the
dimensional reduction in the lowest Landau levels.Comment: Contribution to the proceedings of Quark Matter 2017 in Chicag
Anatomy of the magnetic catalysis by renormalization-group method
We first examine the scaling argument for a renormalization-group (RG)
analysis applied to a system subject to the dimensional reduction in strong
magnetic fields, and discuss the fact that a four-Fermi operator of the
low-energy excitations is marginal irrespective of the strength of the coupling
constant in underlying theories. We then construct a scale-dependent effective
four-Fermi interaction as a result of screened photon exchanges at weak
coupling, and establish the RG method appropriately including the screening
effect, in which the RG evolution from ultraviolet to infrared scales is
separated into two stages by the screening-mass scale. Based on a precise
agreement between the dynamical mass gaps obtained from the solutions of the RG
and Schwinger-Dyson equations, we discuss an equivalence between these two
approaches. Focusing on QED and Nambu--Jona-Lasinio model, we clarify how the
properties of the interactions manifest themselves in the mass gap, and point
out an importance of respecting the intrinsic energy-scale dependences in
underlying theories for the determination of the mass gap. These studies are
expected to be useful for a diagnosis of the magnetic catalysis in QCD.Comment: 8 pages, 3 figures, version published in PL
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