1,965 research outputs found
Quasiparticle picture of quarks near chiral transition at finite temperature
We investigate, using a chiral effective model, the quark spectrum in the
critical region of the chiral transition focusing on the effect of the possible
mesonic excitations in the quark-gluon plasma phase. We find that there appears
a novel three-peak structure in the quark spectra. We elucidate the mechanism
of the appearance of the multi-peak structure with the help of a Yukawa model
with an elementary boson.Comment: 4 pages, 5 eps figures, to appear in the proceedings of International
Conference on Strong & Electroweak Matter 2006, Brookhaven National
Laboratory, USA, May 10-13, 200
Gaugino Condensation in Heterotic Fivebrane Background
The gaugino propagator is calculated by explicitly considering the
propagation of a heterotic string between two different points in space-time
using the non-trivial world-sheet conformal field theory for the fivebrane
background. We find that there are no propagations of gaugino which is in the
spinor representation of the non-trivial four-dimensional space of the
fivebrane background. This result is consistent with the arguments on the
fermion zero-modes of the fivebrane background in the low-energy heterotic
supergravity theory. Furthermore, assuming the continuous limit to the flat
space-time background at the place far away from the fivebrane, we suggest an
effective propagator which is effective only at the place far away from the
fivebrane in the flat space-time limit. From the effective propagator we
evaluate a possible gaugino pair condensation. The result is consistent with
the suggested scenario of the gaugino condensation in the fivebrane background
in the low-energy heterotic supergravity theory.Comment: 14 page
Precursor of Color Superconductivity
We investigate possible precursory phenomena of color superconductivity at
finite temperature with an effective theory of QCD. It is found that the
fluctuation of the diquark pair field exists with a prominent strength even
well above the critical temperature . We show that such a fluctuaiton
forms a collective mode, the corresponding pole of which approaches the origin
as is lowered to in the complex energy plane. We discuss the possible
relevance of the precursor to the observables to be detected in heavy-ion
collisions.Comment: 4 pages, 5 figures, Talk presented at the XVIth International
Conference on Particles and Nuclei (PANIC02), Osaka, Japan, Sep.30 - Oct.4,
2002, Uses espcrc1.st
String Field Theory from IIB Matrix Model
We derive Schwinger-Dyson equations for the Wilson loops of a type IIB matrix
model. Superstring coordinates are introduced through the construction of the
loop space. We show that the continuum limit of the loop equation reproduces
the light-cone superstring field theory of type IIB superstring in the large-N
limit. We find that the interacting string theory can be obtained in the double
scaling limit as it is expected.Comment: 21 pages, Latex, 1 figur
Precursor of Color Superconductivity in Hot Quark Matter
We investigate possible precursory phenomena of color superconductivity in
quark matter at finite temperature T with use of a simple Nambu-Jona-Lasinio
model. It is found that the fluctuating pair field exists with a prominent
strength even well above the critical temperature T_c. We show that the
collective pair field has a complex energy located in the second Riemann sheet,
which approaches the origin as T is lowered to T_c. We discuss the possible
relevance of the precursor to the observables to be detected in heavy ion
collisions.Comment: 5 pages, 3 figures, version to appear in Phys. Rev. D. Discussions
are enlarged on the physical origin of the large fluctuation of the pair
field and its phenomenological consequences. References are adde
symmetry of the BKT transition and twisted boundary conditio n
Berezinskii-Kosterlitz-Thouless (BKT) transition, the transition of the 2D
sine-Gordon model, plays an important role in the low dimensional physics. We
relate the operator content of the BKT transition to that of the SU(2)
Wess-Zumino-Witten model, using twisted boundary conditions. With this method,
in order to determine the BKT critical point, we can use the level crossing of
the lower excitations than the periodic boundary case, thus the convergence to
the transition point is highly improved. Then we verify the efficiency of this
method by applying to the S=1,2 spin chains.Comment: LaTex2e,, 33 pages, 14 figures in eps file
BCS-BEC crossover in a relativistic superfluid and its significance to quark matter
The character change of a superfluid state due to the variation of the
attractive force is investigated in the relativistic framework with a massive
fermion. Two crossovers are found. One is a crossover from the usual BCS state
to the Bose-Einstein condensation (BEC) of bound fermion pairs. The other is
from the BEC to the relativistic Bose-Einstein condensation (RBEC) of nearly
massless bound pairs where antiparticles as well as particles dominate the
thermodynamics. Possible realization of the BEC and RBEC states in the quark
matter is also pointed out.Comment: 5 pages, 1 figure, revtex4; (v2) text has been clarified, references
updated; (v3) final version to appear in Phys. Rev.
Treatment of Alzheimer's Disease with Anti-Homocysteic acid Antibody
Homocysteic acid (HA) may play an important role in Alzhiemer disease (AD) as we previously reported that HA induced accumulation of intraneuronal A[beta]42. In this study, we first analyzed HA levels in a mouse model of AD. 4-month old pre-pathologic 3xTg-AD mice exhibited higher levels of HA in the hippocampus as compared to age-matched nontransgenic, suggesting that HA accumulation may precede both A[beta] and tau pathologies. To further determine the pathogenic role of HA in AD, we treated young 3xTg-AD mice with vitamin B6-deficient food for 3 weeks to induce the production of HA in the brain. Concominantly, mice received either saline or anti-HA antibody intraventricularly using a guide cannula every 3 days. Mice received anti-HA antibody significantly rescued cognitive impairment induced by vitamin B6 deficiency. Pathologically, 3-week treatment with vitamin B-6 deficient food resulted in strong neurodegeneration in the hippocampal CA1 zone and decreased hippocampal volume. In contrast, anti-HA antibody treatment attenuated these pathological changes. Taken together, we conclude that increased brain HA triggers memory impairment whose condition was deteriorated by amyloid and subsequent neurodegeneration and reduction of neurogenesis. Our results indicate a pathogenic role of HA in AD
Treatment of Alzheimer's Disease with Anti-Homocysteic acid Antibody
Homocysteic acid (HA) may play an important role in Alzhiemer disease (AD) as we previously reported that HA induced accumulation of intraneuronal A[beta]42. In this study, we first analyzed HA levels in a mouse model of AD. 4-month old pre-pathologic 3xTg-AD mice exhibited higher levels of HA in the hippocampus as compared to age-matched nontransgenic, suggesting that HA accumulation may precede both A[beta] and tau pathologies. To further determine the pathogenic role of HA in AD, we treated young 3xTg-AD mice with vitamin B6-deficient food for 3 weeks to induce the production of HA in the brain. Concominantly, mice received either saline or anti-HA antibody intraventricularly using a guide cannula every 3 days. Mice received anti-HA antibody significantly rescued cognitive impairment induced by vitamin B6 deficiency. Pathologically, 3-week treatment with vitamin B-6 deficient food resulted in strong neurodegeneration in the hippocampal CA1 zone and decreased hippocampal volume. In contrast, anti-HA antibody treatment attenuated these pathological changes. Taken together, we conclude that increased brain HA triggers memory impairment whose condition was deteriorated by amyloid and subsequent neurodegeneration and reduction of neurogenesis. Our results indicate a pathogenic role of HA in AD
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