4,829 research outputs found
Stellar spectroscopy: Fermions and holographic Lifshitz criticality
Electron stars are fluids of charged fermions in Anti-de Sitter spacetime.
They are candidate holographic duals for gauge theories at finite charge
density and exhibit emergent Lifshitz scaling at low energies. This paper
computes in detail the field theory Green's function G^R(w,k) of the
gauge-invariant fermionic operators making up the star. The Green's function
contains a large number of closely spaced Fermi surfaces, the volumes of which
add up to the total charge density in accordance with the Luttinger count.
Excitations of the Fermi surfaces are long lived for w <~ k^z. Beyond w ~ k^z
the fermionic quasiparticles dissipate strongly into the critical Lifshitz
sector. Fermions near this critical dispersion relation give interesting
contributions to the optical conductivity.Comment: 38 pages + appendices. 9 figure
Electronic Liquid Crystal Phases of a Doped Mott Insulator
The character of the ground state of an antiferromagnetic insulator is
fundamentally altered upon addition of even a small amount of charge. The added
charges agglomerate along domain walls at which the spin correlations, which
may or may not remain long-ranged, suffer a phase shift. In two
dimensions, these domain walls are ``stripes'' which are either insulating, or
conducting, i.e. metallic rivers with their own low energy degrees of freedom.
However, quasi one-dimensional metals typically undergo a transition to an
insulating ordered charge density wave (CDW) state at low temperatures. Here it
is shown that such a transition is eliminated if the zero-point energy of
transverse stripe fluctuations is sufficiently large in comparison to the CDW
coupling between stripes. As a consequence, there exist novel,
liquid-crystalline low-temperature phases -- an electron smectic, with
crystalline order in one direction, but liquid-like correlations in the other,
and an electron nematic with orientational order but no long-range positional
order. These phases, which constitute new states of matter, can be either high
temperature supeconductors or two-dimensional anisotropic ``metallic''
non-Fermi liquids. Evidence for the new phases may already have been obtained
by neutron scattering experiments in the cuprate superconductor,
La_{1.6-x}Nd_{0.4}Sr_xCuO_{4}.Comment: 5 pages in RevTex with two figures in ep
Photoemission "experiments" on holographic superconductors
We study the effects of a superconducting condensate on holographic Fermi
surfaces. With a suitable coupling between the fermion and the condensate,
there are stable quasiparticles with a gap. We find some similarities with the
phenomenology of the cuprates: in systems whose normal state is a non-Fermi
liquid with no stable quasiparticles, a stable quasiparticle peak appears in
the condensed phase.Comment: 14 pages, 13 figures; v2: typos corrected and some clarification
adde
Theoretical analysis for the apparent discrepancy between pbarp and pp data in charged particle forward-backward multiplicity correlations
The strength of charged particle forward-backward multiplicity correlation in
pbar+p and p+p collisions at s^1/2 = 200 GeV is studied by PYTHIA 6.4 and
compared to the UA5 and STAR data correspondingly. It is turned out that a
factor of 3-4 apparent discrepancy between UA5 and STAR data can be attributed
to the differences in detector acceptances and observing bin interval in both
experiments. A mixed event method is introduced and used to calculate the
statistical correlation strength and the dynamical correlation strengths
stemming from the charge conservation, four- momentum conservation, and decay,
respectively. It seems that the statistical correlation is much larger than
dynamical one and the charge conservation, four-momentum conservation and decay
may account for most part of the dynamical correlation. In addition, we have
also calculated the correlation strength by fitting the charged particle
multiplicity distribution from PYTHIA to the Negative Binomial Distribution and
found that the result agrees well with the correlation strength calculated by
mixed events.Comment: 5 pages, 4 figure
Successful monitoring of the 11 April 2012 tsunami off the coast of Sumatra by Indian Tsunami Early Warning Centre
The Indian Tsunami Early Warning Centre (ITEWC) in Hyderabad monitored the 11 April 2012 tsunami off the coast of Sumatra, which was generated by a shallow strike-slip earthquake and it largest aftershock of magnitude Mw (mB) 8.5 and 8.2 respectively, that occurred inside the subducting slab of the Indian plate. The earthquake generated a small ocean-wide tsunami that has been recorded by various tide gauges and tsunami buoys located in the Indian Ocean region. ITEWC detected the earthquake within 3 min 52 s and issued six advisories (bulletins) according to its Standard Operating Procedure. The ITEWC performed well during the event, and avoided false alarms and unnecessary public evacuations, especially in the mainland part of India region
QGP flow fluctuations and the characteristics of higher moments
The dynamical development of expanding Quark-gluon Plasma (QGP) flow is
studied in a 3+1D fluid dynamical model with a globally symmetric, initial
condition. We minimize fluctuations arising from complex dynamical processes at
finite impact parameters and from fluctuating random initial conditions to have
a conservative fluid dynamical background estimate for the statistical
distributions of the thermodynamical parameters. We also avoid a phase
transition in the equation of state, and we let the matter supercool during the
expansion.
Then central Pb+Pb collisions at TeV are studied in an
almost perfect fluid dynamical model, with azimuthally symmetric initial state
generated in a dynamical flux-tube model. The general development of
thermodynamical extensives are also shown for lower energies.
We observe considerable deviations from a thermal equilibrium source as a
consequence of the fluid dynamical expansion arising from a least fluctuating
initial state
A single-photon transistor using nano-scale surface plasmons
It is well known that light quanta (photons) can interact with each other in
nonlinear media, much like massive particles do, but in practice these
interactions are usually very weak. Here we describe a novel approach to
realize strong nonlinear interactions at the single-photon level. Our method
makes use of recently demonstrated efficient coupling between individual
optical emitters and tightly confined, propagating surface plasmon excitations
on conducting nanowires. We show that this system can act as a nonlinear
two-photon switch for incident photons propagating along the nanowire, which
can be coherently controlled using quantum optical techniques. As a novel
application, we discuss how the interaction can be tailored to create a
single-photon transistor, where the presence or absence of a single incident
photon in a ``gate'' field is sufficient to completely control the propagation
of subsequent ``signal'' photons.Comment: 20 pages, 4 figure
Dynamical approach to spectator fragmentation in Au+Au reactions at 35 MeV/A
The characteristics of fragment emission in peripheral Au+Au
collisions 35 MeV/A are studied using the two clusterization approaches within
framework of \emph{quantum molecular dynamics} model. Our model calculations
using \emph{minimum spanning tree} (MST) algorithm and advanced clusterization
method namely \emph{simulated annealing clusterization algorithm} (SACA) showed
that fragment structure can be realized at an earlier time when spectators
contribute significantly toward the fragment production even at such a low
incident energy. Comparison of model predictions with experimental data reveals
that SACA method can nicely reproduce the fragment charge yields and mean
charge of the heaviest fragment. This reflects suitability of SACA method over
conventional clusterization techniques to investigate spectator matter
fragmentation in low energy domain.Comment: 6 pages, 5 figures, accepte
A Case of the Inferior Mesenteric Artery Arising from the Superior Mesenteric Artery in a Korean Woman
Anatomical variations of the inferior mesenteric artery are extremely uncommon, since the inferior mesenteric artery is regularly diverged at the level of the third lumbar vertebra. We found a rare case in which the inferior mesenteric artery arose from the superior mesenteric artery. The findings were made during a routine dissection of the cadaver of an 82-yr-old Korean woman. This is the tenth report on this anomaly, the second female and the first Korean. The superior mesenteric artery normally arising from abdominal aorta sent the inferior mesenteric artery as the second branch. The longitudinal anastomosis vessels between the superior mesenteric artery and inferior mesenteric artery survived to form the common mesenteric artery. This anatomical variation concerning the common mesenteric artery is of clinical importance, performing procedures containing the superior mesenteric artery
Charged, conformal non-relativistic hydrodynamics
We embed a holographic model of an U(1) charged fluid with Galilean
invariance in string theory and calculate its specific heat capacity and
Prandtl number. Such theories are generated by a R-symmetry twist along a null
direction of a N=1 superconformal theory. We study the hydrodynamic properties
of such systems employing ideas from the fluid-gravity correspondence.Comment: 31 pages, 1 figure, JHEP3 style, refs added, typos corrected, missing
terms in spatial charge current and field corrections added, to be published
in JHE
- …