506 research outputs found
Black Hole Production from High Energy Scattering in AdS/CFT
In this article we show how to set up initial states in SYM
theory that correspond to high energy graviton collisions, leading to black
hole formation in . For this purpose, we study states in the
gauge theory that are dual to graviton wavepackets localized at the center of
, and carrying large angular momentum along the . These states are
created by exciting only the s-wave mode of one of the complex adjoint scalars
of SYM. For a single graviton, the state is 1/2 BPS and one can show that it is
dual to a linearized 1/2 BPS geometry in the bulk. Exploiting this dictionary,
we show how to localize the particle's wavefunciton so that the dual linearized
metric has the form of a Aichelburg-Sexl shock wave. One can then put two such
shock waves into a head-on collision, which is known to produce a trapped
surface. Finally, we discuss the prospect of studying graviton scattering
directly at strong coupling in the gauge theory using a reduced model of matrix
quantum mechanics.Comment: 11 pages, revtex format, no figure
Emergent Classical Strings from Matrix Model
Generalizing the idea of hep-th/0509015 by Berenstein, Correa, and Vazquez,
we study many-magnon states in an SU(2) sector of a reduced matrix quantum
mechanics obtained from N=4 SU(N) super Yang-Mills on R x S^3. Generic Q-magnon
states are described as a chain of ``string-bits'' joining Q+1 eigenvalues of
background matrices which form a 1/2 BPS circular droplet in the large N limit.
We will concentrate on infinitely long states whose first and last eigenvalues
localize at the edge of the droplet. Each constituent string-bit has a complex
quasi-momentum in general, while the total quasi-momentum P of the state is
real. For given Q and P, the minimum energy of the chain of string-bits is
realized when the Q+1 eigenvalues are equally spaced on one and the same line
segment joining the two outmost eigenvalues localized on the edge with angular
difference P. Such configuration of bound string-bits precisely reproduces the
dispersion relation for dyonic giant magnons in classical string theory. We
also show the emergence of two-spin folded/circular strings in special infinite
spin limit as particular configurations of closed chains of string-bits.Comment: 1+23 pages, 3 figure
Strings on conifolds from strong coupling dynamics, part I
A method to solve various aspects of the strong coupling expansion of the
superconformal field theory duals of AdS_5 x X geometries from first principles
is proposed. The main idea is that at strong coupling the configurations that
dominate the low energy dynamics of the field theory compactified on a three
sphere are given by certain non-trivial semi-classical configurations in the
moduli space of vacua.
We show that this approach is self-consistent and permits one to express most
of the dynamics in terms of an effective N=4 SYM dynamics. This has the
advantage that some degrees of freedom that move the configurations away from
moduli space can be treated perturbatively, unifying the essential low energy
dynamics of all of these theories. We show that with this formalism one can
compute the energies of strings in the BMN limit in the Klebanov-Witten theory
from field theory considerations, matching the functional form of results found
using AdS geometry. This paper also presents various other technical results
for the semiclassical treatment of superconformal field theories.Comment: 52 pages, JHEP3 styl
Gravitational Lensing by Black Holes
We review the theoretical aspects of gravitational lensing by black holes,
and discuss the perspectives for realistic observations. We will first treat
lensing by spherically symmetric black holes, in which the formation of
infinite sequences of higher order images emerges in the clearest way. We will
then consider the effects of the spin of the black hole, with the formation of
giant higher order caustics and multiple images. Finally, we will consider the
perspectives for observations of black hole lensing, from the detection of
secondary images of stellar sources and spots on the accretion disk to the
interpretation of iron K-lines and direct imaging of the shadow of the black
hole.Comment: Invited article for the GRG special issue on lensing (P. Jetzer, Y.
Mellier and V. Perlick Eds.). 31 pages, 12 figure
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in âs = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fbâ1 of protonâproton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC
Measurements of inclusive jet suppression in heavy ion collisions at the LHC
provide direct sensitivity to the physics of jet quenching. In a sample of
lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated
luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with
a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the
transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the
anti-kt algorithm with values for the distance parameter that determines the
nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of
the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp.
Jet production is found to be suppressed by approximately a factor of two in
the 10% most central collisions relative to peripheral collisions. Rcp varies
smoothly with centrality as characterized by the number of participating
nucleons. The observed suppression is only weakly dependent on jet radius and
transverse momentum. These results provide the first direct measurement of
inclusive jet suppression in heavy ion collisions and complement previous
measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables,
submitted to Physics Letters B. All figures including auxiliary figures are
available at
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02
The impact of the metabotropic glutamate receptor and other gene family interaction networks on autism
Although multiple reports show that defective genetic networks underlie the aetiology of autism, few have translated into pharmacotherapeutic opportunities. Since drugs compete with endogenous small molecules for protein binding, many successful drugs target large gene families with multiple drug binding sites. Here we search for defective gene family interaction networks (GFINs) in 6,742 patients with the ASDs relative to 12,544 neurologically normal controls, to find potentially druggable genetic targets. We find significant enrichment of structural defects (Pâ€2.40E-09, 1.8-fold enrichment) in the metabotropic glutamate receptor (GRM) GFIN, previously observed to impact attention deficit hyperactivity disorder (ADHD) and schizophrenia. Also, the MXD-MYC-MAX network of genes, previously implicated in cancer, is significantly enriched (Pâ€3.83E-23, 2.5-fold enrichment), as is the calmodulin 1 (CALM1) gene interaction network (Pâ€4.16E-04, 14.4-fold enrichment), which regulates voltage-independent calcium-activated action potentials at the neuronal synapse. We find that multiple defective gene family interactions underlie autism, presenting new translational opportunities to explore for therapeutic interventions
Autoantibodies against type I IFNs in patients with life-threatening COVID-19
Interindividual clinical variability in the course of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is vast. We report that at least 101 of 987 patients with life-threatening coronavirus disease 2019 (COVID-19) pneumonia had neutralizing immunoglobulin G (IgG) autoantibodies (auto-Abs) against interferon-w (IFN-w) (13 patients), against the 13 types of IFN-a (36), or against both (52) at the onset of critical disease; a few also had auto-Abs against the other three type I IFNs. The auto-Abs neutralize the ability of the corresponding type I IFNs to block SARS-CoV-2 infection in vitro. These auto-Abs were not found in 663 individuals with asymptomatic or mild SARS-CoV-2 infection and were present in only 4 of 1227 healthy individuals. Patients with auto-Abs were aged 25 to 87 years and 95 of the 101 were men. A B cell autoimmune phenocopy of inborn errors of type I IFN immunity accounts for life-threatening COVID-19 pneumonia in at least 2.6% of women and 12.5% of men
Measurement of prompt hadron production ratios in collisions at 0.9 and 7 TeV
The charged-particle production ratios , , ,
, and are measured with the LHCb detector using of collisions delivered by the LHC at TeV and
at TeV. The measurements are performed as a
function of transverse momentum and pseudorapidity . The
production ratios are compared to the predictions of several Monte Carlo
generator settings, none of which are able to describe adequately all
observables. The ratio is also considered as a function of rapidity
loss, , and is used to constrain models of
baryon transport.Comment: Incorrect entries in Table 2 corrected. No consequences for rest of
pape
- âŠ