1,890 research outputs found
The Fate of Hadron Masses in Dense Matter: Hidden Local Symmetry and Color Flavor Locking
The notion that hadron masses scale according to the scaling of the quark
condensate in hadronic matter, partly supported by a number of observations in
finite nuclei, can be interpreted in terms of Harada-Yamawaki's ``vector
manifestation" (VM) of chiral symmetry. In this scenario, near chiral
restoration, the vector meson masses drop to zero {\it in the chiral limit}
with vanishing widths. This scenario appears to differ from the standard linear
sigma model scenario. We exploit a link between the VM and color-flavor locking
inferred by us from lattice data on quark number susceptibility (QNS) measured
as a function of temperature to suggest that local flavor symmetry gets mapped
to color gauge symmetry at the chiral phase transition.Comment: 5 pages, revised with title change, sharpened arguments and updated
reference
Double Decimation and Sliding Vacua in the Nuclear Many-Body System
We propose that effective field theories for nuclei and nuclear matter
comprise of "double decimation": (1) the chiral symmetry decimation (CSD) and
(2) Fermi liquid decimation (FLD). The Brown-Rho scaling recently identified as
the parametric dependence intrinsic in the "vector manifestation" of hidden
local symmetry theory of Harada and Yamawaki results from the first decimation.
This scaling governs dynamics down to the scale at which the Fermi surface is
formed as a quantum critical phenomenon. The next decimation to the top of the
Fermi sea where standard nuclear physics is operative makes up the Fermi liquid
decimation. Thus nuclear dynamics is dictated by two fixed points, namely, the
vector manifestation fixed point and the Fermi liquid fixed point. It has been
a prevalent practice in nuclear physics community to proceed with the second
decimation only, assuming density independent masses. We show why most nuclear
phenomena can be reproduced by theories using either density-independent, or
density-dependent masses, a grand conspiracy of nature that is an aspect that
could be tied to the Cheshire-Cat phenomenon in hadron physics. We identify
what is left out in the Fermi liquid decimation that does not incorporate the
CSD. Experiments such as the dilepton production in relativistic heavy ion
reactions, which are specifically designed to observe effects of dropping
masses, could exhibit large effects from the reduced masses. However they are
compounded with effects that are not directly tied to chiral symmetry. We
discuss a recent STAR/RHIC observation where BR scaling can be singled out in a
pristine environment.Comment: Latex, 9 figures; based on version prepared for Phys. Re
Matching the QCD and Hadron Sectors and Medium Dependent Meson Masses; Hadronization in Relativistic Heavy Ion Collisions
The recent developments on the "vector manifestation" of chiral symmetry by
Harada and Yamawaki provide a compelling evidence for, and "refine," the
in-medium scaling of hadronic properties in dense/hot matter (call it ``BR
scaling") proposed by the authors in 1991. We reinterpret the Harada-Yamawaki
result obtained in a Wilsonian renormalization-group approach to hidden local
symmetry theory matched to QCD at near the chiral scale in terms of the
Nambu-Jona-Lasinio model and predict that the vector meson mass in medium
should scale m_\rho^\star/m_\rho\sim
(\la\bar{q}q\ra^\star/\la\bar{q}q\ra)^{1/2} from up to
(where is nuclear matter density) and then go over to the linear scaling
m_\rho^\star/m_\rho\sim \la\bar{q}q\ra^\star/\la\bar{q}q\ra up to the chiral
transition density at which the mass is to vanish (in the chiral limit)
according to the vector manifestation fixed point. In the regime of the linear
scaling above , the (vector) gauge coupling constant should fall linearly
in \la\bar{q}q\ra^\star, vanishing at the critical point, with the width of
the vector meson becoming steeply narrower. We suggest the in-medium vector
meson mass, {\em both} parametric and pole, which goes smoothly to zero with
increasing density, to be an order parameter for chiral symmetry restoration.
Some issues related to recent RHIC observations are qualitatively discussed in
the appendices. Our main conclusion that follows from these considerations is
that the movement towards chiral restoration can be reliably described in
Nambu-Jona-Lasinio mean field, with constituent quarks as variables, although
there is probably density discontinuity following chiral restoration.Comment: Contribution to the Hidenaga Yamagishi Commemorative Volume edited by
E. Witten and I.Zahe
On the Manifestation of Chiral Symmetry in Nuclei and Dense Nuclear Matter
This article reviews our view on how chiral symmetry, its pattern of breaking
and restoration under extreme conditions manifest themselves in the nucleon,
nuclei, nuclear matter and dense hadronic matter. Topics treated are nucleon
structure in terms of chiral symmetry, "first-principle" (QCD) calculations of
the properties of finite nuclei effectuated by embedding the ``standard nuclear
physics approach" into the framework of effective field theories of nuclei with
predictions for certain astrophysical processes, a reinterpretation of the
Brown-Rho (BR) scaling that implements chiral symmetry property of baryon-rich
medium \`a la "vector manifestation" of hidden local symmetry, evidences for BR
scaling in nuclear processes at normal nuclear matter density and at higher
density, the notion of "broadband equilibration" in heavy-ion processes, and
the role of strangeness in the formation of compact stars and their collapse
into black-holes. We revisit the "Cheshire-Cat phenomenon" recently revived in
the form of "quark-hadron continuity" in mapping low-density structure of
hadrons to high-density structure of quarks and gluons and suggest how
color-flavor locking in terms of QCD variables and hidden local symmetry in
terms of hadronic variables may be connected and how BR scaling could fit into
this "continuity" scheme.Comment: 103 pages, latex, 14 figures; Physics Reports; references updated and
new developments adde
Strangeness Equilibration at GSI Energies
We develop the notion of "broad-band equilibration" in heavy-ion processes
involving dense medium. Given density-dependent \Km-masses we show that the
equilibration at GSI energies claimed to hold in previous treatments down to
, can be replaced by a broad-band equilibration in which the
\Km-meson and hyperons are produced in an essentially constant ratio
independent of density. There are experimental indications that this also holds
for AGS energies. We then proceed to argue that {\it both} and must
get lighter in dense medium at some density due to the
decoupling of the vector mesons. As a consequence, kaon condensation in compact
stars could take place {\it before} chiral restoration since the sum of bare
quark masses in the kaon should lie below . Another consequence of the
decoupling vector interactions is that the quasi-particle picture involving
(quasi)quarks, presumably ineffective at low densities, becomes more
appropriate at higher densities as chiral restoration is approached.Comment: 16 pages, latex with 2 eps figures. Abstract rewritten and references
update
A Schematic Model For Density-Dependent Vector Meson Masses
A schematic two-level model consisting of a "collective" bosonic state and an
"elementary" meson is constructed that provides interpolation from a hadronic
description (a la Rapp/Wambach) to B/R scaling for the description of
properties of vector mesons in dense medium. The development is based on a
close analogy to the degenerate schematic model of Brown for giant resonances
in nuclei.Comment: 20 pages, latex with 8 figures: Talk given by GEB at AIP Klaus
Kinder-Geiger Memorial Meeting, 3 October 199
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