197 research outputs found
Bosonized noncommutative bi-fundamental fermion and S-duality
We perform the path-integral bosonization of the recently proposed
noncommutative massive Thirring model (NCMT) [JHEP0503(2005)037]. This
model presents two types of current-current interaction terms related to the
bi-fundamental representation of the group U(1). Firstly, we address the
bosonization of a bi-fundamental free Dirac fermion defined on a noncommutative
(NC) Euclidean plane \IR_{\theta}^{2}. In this case we show that the fermion
system is dual to two copies of the NC Wess-Zumino-Novikov-Witten model. Next,
we apply the bosonization prescription to the NCMT model living on
\IR_{\theta}^{2} and show that this model is equivalent to two-copies of the
WZNW model and a two-field potential defined for scalar fields corresponding to
the global symmetry plus additional bosonized terms for the
four fermion interactions. The bosonic sector resembles to the one proposed by
Lechtenfeld et al. [Nucl. Phys. B705(2005)477] as the noncommutative
sine-Gordon for a {\sl pair} of scalar fields. The bosonic and fermionic
couplings are related by a strong-weak duality. We show that the couplings of
the both sectors for some representations satisfy similar relationships up to
relevant re-scalings, thus the NC bi-fundamental couplings are two times the
corresponding ones of the NC fundamental (anti-fundamental) and eight times the
couplings of the ordinary massive Thirring and sine-Gordon models.Comment: 18 pages, LaTex. References added. A general product has been considered in the conclusion section . Version to appear in
JHE
Light-like noncommutativity and duality from open strings/branes
In this paper we perform some non-trivial tests for the recently obtained
open membrane/D-brane metrics and `generalized' noncommutativity parameters
using Dp/NS5/M5-branes which have been deformed by light-like fields. The
results obtained give further evidence that these open membrane/D-brane metrics
and `generalized' noncommutativity parameters are correct. Further, we use the
open brane data and supergravity duals to obtain more information about
non-gravitational theories with light-like noncommutativity, or `generalized'
light-like noncommutativity. In particular, we investigate various duality
relations (strong coupling limits). In the light-like case we also comment on
the relation between open membrane data (open membrane metric etc.) in six
dimensions and open string data in five dimensions. Finally, we investigate the
strong coupling limit (high energy limit) of five dimensional NCYM with
\Theta^{12}=\Theta^{34}. In particular, we find that this NCYM theory can be UV
completed by a DLCQ compactification of M-theory.Comment: 24 pages, Latex. v2:Comments and references added. v3:Version
published in JHE
Brane Cosmology in the Background of D-Brane with NS B Field
We study the cosmological evolution of the four-dimensional universe on the
probe D3-brane in geodesic motion in the curved background of the source
Dp-brane with non-zero NS B field. The Friedman equations describing the
expansion of the brane universe are obtained and analyzed for various limits.
We elaborate on corrections to the cosmological evolution due to nonzero NS B
field.Comment: 13 pages, LaTeX, revised version with minor corrections to appear in
Phys. Rev.
Three-Particle Correlations from Parton Cascades in Au+Au Collisions
We present a study of three-particle correlations among a trigger particle
and two associated particles in Au + Au collisions at = 200 GeV
using a multi-phase transport model (AMPT) with both partonic and hadronic
interactions. We found that three-particle correlation densities in different
angular directions with respect to the triggered particle (`center', `cone',
`deflected', `near' and `near-away') increase with the number of participants.
The ratio of `deflected' to `cone' density approaches to 1.0 with the
increasing of number of participants, which indicates that partonic Mach-like
shock waves can be produced by strong parton cascades in central Au+Au
collisions.Comment: 9 pages, 6 figures; Final version to appear in Physics Letters
Non-Extremal D-instantons and the AdS/CFT Correspondence
We investigate non-extremal D-instantons in an asymptotically background and the role they play in the correspondence.
We find that the holographic dual operators of non-extremal D-instanton
configurations do not correspond to self-dual Yang-Mills instantons, and we
compute explicitly the deviation from self-duality. Furthermore, a class of
non-extremal D-instantons yield Euclidean axionic wormhole solutions with two
asymptotic boundaries. After Wick rotating, this provides a playground for
investigating holography in the presence of cosmological singularities in a
closed universe.Comment: 30 pages, 3 figure
Di-hadron azimuthal correlation and Mach-like cone structure in parton/hadron transport model
In the framework of a multi-phase transport model (AMPT) with both partonic
and hadronic interactions, azimuthal correlations between trigger particles and
associated scattering particles have been studied by the mixing-event
technique. The momentum ranges of these particles are
GeV/ and GeV/ (soft), or 4
GeV/ and GeV/ (hard) in Au + Au collisions at
= 200 GeV. A Mach-like structure has been observed in
correlation functions for central collisions. By comparing scenarios with and
without parton cascade and hadronic rescattering, we show that both partonic
and hadronic dynamical mechanisms contribute to the Mach-like structure of the
associated particle azimuthal correlations. The contribution of hadronic
dynamical process can not be ignored in the emergence of Mach-like correlations
of the soft scattered associated hadrons. However, hadronic rescattering alone
cannot reproduce experimental amplitude of Mach-like cone on away-side, and the
parton cascade process is essential to describe experimental amplitude of
Mach-like cone on away-side. In addition, both the associated multiplicity and
the sum of decrease, whileas the increases, with the impact
parameter in the AMPT model including partonic dynamics from string melting
scenario.Comment: 9 pages, 5 figures; Physics Letters B 641, 362-367 (2006
SL(2, Z) Duality and 4-Dimensional Noncommutative Theories
We investigate how the four-dimensional noncommutative open string/Yang-Mills
theory behaves under a general non-perturbative quantum symmetry
transformation. We discuss this by considering D3 branes in a constant
background of axion, dilaton, and electric and magnetic fields (including both
and {\bf E}{\bf B} cases) in the respective
decoupling limit. We find that the value of axion, whether rational or
irrational, determines the nature of the resulting theory under as
well as its properties such as the coupling constant and the number of
noncommutative directions. In particular, a strongly coupled theory with an
irrational value of axion can never be physically equivalent to a weakly
coupled theory while this is usually true for a theory with a rational value of
axion. A noncommutative Yang-Mills (NCYM) (resulting from D3 branes with pure
magnetic flux) is physically equivalent to a noncommutative open string (NCOS)
but if the value of axion is irrational, we also have noncommutative
space-space directions in addition to the usual noncommutative space-time
directions for NCOS. We also find in general that a NCOS cannot be physically
equivalent to a NCYM but to another NCOS if the value of axion is irrational.
We find another new decoupling limit for possible light-like NCYM whose
duality is a light-like ordinary Yang-Mills if the value of the axion
is rational. Various related questions are also discussed.Comment: 22 pages, late
Wilson Loop and Dimensional Reduction in Non-Commutative Gauge Theories
Using the AdS/CFT correspondence we study UV behavior of Wilson loops in
various noncommutative gauge theories. We get an area law in most cases and try
to identify its origin. In D3 case, we may identify the the origin as the D1
dominance over the D3: as we go to the boundary of the AdS space, the effect of
the flux of the D3 charge is highly suppressed, while the flux due to the D1
charge is enhenced. So near the boundary the theory is more like a theory on D1
brane than that on D3 brane. This phenomena is closely related to the
dimensional reduction due to the strong magnetic field in the charged particle
in the magnetic field. The linear potential is not due to the confinement by IR
effect but is the analogue of Coulomb's potential in 1+1 dimension.Comment: v2: references added, v3:include comparison with hep-th/0010256.
v4=v3(mailer error), v5= to appear in pr
Partonic flow and -meson production in Au+Au collisions at = 200 GeV
We present first measurements of the -meson elliptic flow
() and high statistics distributions for different
centralities from = 200 GeV Au+Au collisions at RHIC. In
minimum bias collisions the of the meson is consistent with the
trend observed for mesons. The ratio of the yields of the to those of
the as a function of transverse momentum is consistent with a model
based on the recombination of thermal quarks up to GeV/,
but disagrees at higher momenta. The nuclear modification factor () of
follows the trend observed in the mesons rather than in
baryons, supporting baryon-meson scaling. Since -mesons are
made via coalescence of seemingly thermalized quarks in central Au+Au
collisions, the observations imply hot and dense matter with partonic
collectivity has been formed at RHIC.Comment: 6 pages, 4 figures, submit to PR
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