4,072 research outputs found
Integrability of the symmetry reduced bosonic dynamics and soliton generating transformations in the low energy heterotic string effective theory
Integrable structure of the symmetry reduced dynamics of massless bosonic
sector of the heterotic string effective action is presented. For string
background equations that govern in the space-time of dimensions ()
the dynamics of interacting gravitational, dilaton, antisymmetric tensor and
any number of Abelian vector gauge fields, all depending only on two
coordinates, we construct an \emph{equivalent} matrix
spectral problem (). This spectral problem provides the base for the
development of various solution constructing procedures (dressing
transformations, integral equation methods). For the case of the absence of
Abelian gauge fields, we present the soliton generating transformations of any
background with interacting gravitational, dilaton and the second rank
antisymmetric tensor fields. This new soliton generating procedure is available
for constructing of various types of field configurations including stationary
axisymmetric fields, interacting plane, cylindrical or some other types of
waves and cosmological solutions.Comment: 4 pages; added new section on Belinski-Zakharov solitons and new
expressions for calculation of the conformal factor; corrected typo
Spin Physics at COMPASS
The COMPASS experiment is a fixed target experiment at the CERN SPS using
muon and hadron beams for the investigation of the spin structure of the
nucleon and hadron spectroscopy. The main objective of the muon physics program
is the study of the spin of the nucleon in terms of its constituents, quarks
and gluons. COMPASS has accumulated data during 6 years scattering polarized
muons off a longitudinally or a transversely polarized deuteron (6LiD) or
proton (NH3) target. Results for the gluon polarization are obtained from
longitudinal double spin cross section asymmetries using two different
channels, open charm production and high transverse momentum hadron pairs, both
proceeding through the photon-gluon fusion process. Also, the longitudinal spin
structure functions of the proton and the deuteron were measured in parallel as
well as the helicity distributions for the three lightest quark flavors. With a
transversely polarized target, results were obtained with proton and deuteron
targets for the Collins and Sivers asymmetries for charged hadrons as well as
for identified kaons and pions. The Collins asymmetry is sensitive to the
transverse spin structure of the nucleon, while the Sivers asymmetry reflects
correlations between the quark transverse momentum and the nucleon spin.
Recently, a new proposal for the COMPASS II experiment was accepted by the CERN
SPS which includes two new topics: Exclusive reactions like DVCS and DVMP using
the muon beam and a hydrogen target to study generalized parton distributions
and Drell-Yan measurements using a pion beam and a polarized NH3 target to
study transverse momentum dependent distributions.Comment: Proceedings of the Rutherford conference, Manchester, August 2011.
Changes due to referees comments implemente
Using supernova neutrinos to monitor the collapse, to search for gravity waves and to probe neutrino masses
We discuss the importance of observing supernova neutrinos. By analyzing the
SN1987A observations of Kamiokande-II, IMB and Baksan, we show that they
provide a 2.5{\sigma} support to the standard scenario for the explosion. We
discuss in this context the use of neutrinos as trigger for the search of the
gravity wave impulsive emission. We derive a bound on the neutrino mass using
the SN1987A data and argue, using simulated data, that a future galactic
supernova could probe the sub-eV region.Comment: 8 pages, 1 figure. Proceeding for the Galileo-Xu Guangqi meeting: The
Sun, the Stars, the Universe and General Relativity; October 26-30, 2009,
Shanghai (China). Accepted for publication at International Journal of Modern
Physics
2D Conformal Field Theories and Holography
It is known that the chiral part of any 2d conformal field theory defines a
3d topological quantum field theory: quantum states of this TQFT are the CFT
conformal blocks. The main aim of this paper is to show that a similar CFT/TQFT
relation exists also for the full CFT. The 3d topological theory that arises is
a certain ``square'' of the chiral TQFT. Such topological theories were studied
by Turaev and Viro; they are related to 3d gravity. We establish an
operator/state correspondence in which operators in the chiral TQFT correspond
to states in the Turaev-Viro theory. We use this correspondence to interpret
CFT correlation functions as particular quantum states of the Turaev-Viro
theory. We compute the components of these states in the basis in the
Turaev-Viro Hilbert space given by colored 3-valent graphs. The formula we
obtain is a generalization of the Verlinde formula. The later is obtained from
our expression for a zero colored graph. Our results give an interesting
``holographic'' perspective on conformal field theories in 2 dimensions.Comment: 29+1 pages, many figure
On interrelations between Sibgatullin's and Alekseev's approaches to the construction of exact solutions of the Einstein-Maxwell equations
The integral equations involved in Alekseev's "monodromy transform" technique
are shown to be simple combinations of Sibgatullin's integral equations and
normalizing conditions. An additional complex conjugation introduced by
Alekseev in the integrands makes his scheme mathematically inconsistent;
besides, in the electrovac case all Alekseev's principal value integrals
contain an intrinsic error which has never been identified before. We also
explain how operates a non-trivial double-step algorithm devised by Alekseev
for rewriting, by purely algebraic manipulations and in a different (more
complicated) parameter set, any particular specialization of the known
analytically extended N-soliton electrovac solution obtained in 1995 with the
aid of Sibgatullin's method.Comment: 7 pages, no figures, section II extende
Nonlinear dynamics and band transport in a superlattice driven by a plane wave
A quantum particle transport induced in a spatially-periodic potential by a
propagating plane wave has a number important implications in a range of
topical physical systems. Examples include acoustically driven semiconductor
superlattices and cold atoms in optical crystal. Here we apply kinetic
description of the directed transport in a superlattice beyond standard linear
approximation, and utilize exact path-integral solutions of the semiclassical
transport equation. We show that the particle drift and average velocities have
non-monotonic dependence on the wave amplitude with several prominent extrema.
Such nontrivial kinetic behaviour is related to global bifurcations developing
with an increase of the wave amplitude. They cause dramatic transformations of
the system phase space and lead to changes of the transport regime. We describe
different types of phase trajectories contributing to the directed transport
and analyse their spectral content
The extensions of gravitational soliton solutions with real poles
We analyse vacuum gravitational "soliton" solutions with real poles in the
cosmological context. It is well known that these solutions contain
singularities on certain null hypersurfaces. Using a Kasner seed solution, we
demonstrate that these may contain thin sheets of null matter or may be simple
coordinate singularities, and we describe a number of possible extensions
through them.Comment: 14 pages, LaTeX, 6 figures included using graphicx; to appear in Gen.
Rel. Gra
Anomalous Hydrodynamics
Our goal is to examine the role of anomalies in the hydrodynamic regime of
field theories. We employ methods based on gauge/gravity duality to examine
R-charge anomalies in the hydrodynamic regime of stronly t'Hooft coupled, large
N, N = 4 Super Yang-Mills. We use a single particle spectrum treatment based on
the familiar "level crossing" picture of chiral anomalies to investigate
thermalized, massless QED. In each case, we work in the presence of a
homogeneous background magnetic field, and find the same result. Regardless of
whether a paricular current is anomalously non-conserved or not, as long as it
participates in an anomalous 3-pt. correlator, its constitutive relation
recieves a new term, proportional to a product of the anomaly coefficient, the
magnetic field, and any charge density participating in the anomaly. This
agrees with results found by Alekseev et.al. for QED. We include a general,
symmetry based argument for the presence of such terms, and use linear response
theory to determine their coefficients in a model with anomalous global
charges. This last method we apply to briefly examine baryon transport in
chiral QCD in a strong magnetic field.Comment: 23 pages, 2 figures. To be submitted to JHE
Physical phase space of lattice Yang-Mills theory and the moduli space of flat connections on a Riemann surface
It is shown that the physical phase space of \g-deformed Hamiltonian
lattice Yang-Mills theory, which was recently proposed in refs.[1,2], coincides
as a Poisson manifold with the moduli space of flat connections on a Riemann
surface with handles and therefore with the physical phase space of
the corresponding -dimensional Chern-Simons model, where and are
correspondingly a total number of links and vertices of the lattice. The
deformation parameter \g is identified with and is an
integer entering the Chern-Simons action.Comment: 12 pages, latex, no figure
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