9 research outputs found
Real-time dynamics of axial charge and chiral magnetic current in a non-Abelian (expanding) plasma
Understanding axial charge dynamics driven by changes in Chern-Simons number
densities is a key aspect in understanding the Chiral Magnetic Effect (CME) in
heavy-ion collisions. Most phenomenological simulations assume that a large
amount of axial charge is produced in the initial stages and that axial charge
is conserved throughout the simulation. Within an (expanding) homogeneous
holographic plasma, we investigate the real-time axial charge relaxation
dynamics and their impact on the chiral magnetic current. Moreover, we discuss
the real-time interplay of the non-abelian and the abelian chiral anomaly in
the presence of a strong magnetic field. In the expanding plasma, the
Chern-Simons diffusion rate and thus the axial charge relaxation rate are time
dependent due to the decaying magnetic field. We quantify the changes in the
late time falloffs and establish a horizon formula for the chiral magnetic
current.Comment: 14+2 pages, 6+4 figure
Critical and near-critical relaxation of holographic superfluids
We investigate the relaxation of holographic superfluids after quenches, when
the end state is either tuned to be exactly at the critical point, or very
close to it. By solving the bulk equations of motion numerically, we
demonstrate that in the former case the system exhibits a power law falloff as
well as an emergent discrete scale invariance. The later case is in the regime
dominated by critical slowing down, and we show that there is an intermediate
time-range before the onset of late time exponential falloff, where the system
behaves similarly to the critical point with its power law falloff. We further
postulate a phenomenological Gross-Pitaevskii-like equation that is able to
make quantitative predictions for the behavior of the holographic superfluid
after near-critical quenches. Intriguingly, all parameters of our
phenomenological equation which describes the non-linear time evolution may be
fixed with information from the static equilibrium solutions and linear
response theory.Comment: 8+6 pages, 2+1 figure
Is the chiral magnetic effect fast enough?
While we find within holography that the lifetime of the magnetic field for collider energies like those
achieved at RHIC is long enough to build up the chiral magnetic current, the lifetime of the magnetic
field at LHC seems to be too short. We study the real-time evolution of the chiral magnetic effect out of
equilibrium in strongly coupled holographic gauge theories. We consider the backreaction of the magnetic
field onto the geometry and monitor pressure and chiral magnetic current. Our findings show that
generically, at a small magnetic field, the pressure builds up faster than the chiral magnetic current, whereas
at a strong magnetic field the opposite is true. At large charge, we also find that equilibration is delayed
significantly due to long-lived oscillations. We also match the parameters of our model to QCD parameters
and draw lessons of possible relevance to the realization of the chiral magnetic effect in heavy ion
collisions. In particular, we find an equilibration time of about ∼0.35 fm/c in the presence of the chiral
anomaly for plasma temperatures of order T ∼ 300–400 Me
Non-Hermitian Quantum Quenches in Holography
The notion of non-Hermitian PT symmetric quantum theory has recently been
generalized to the gauge/gravity duality. We study the evolution of such
non-Hermitian holographic field theories when the couplings are varied with
time with particular emphasis on the question non-unitary time vs. unitary time
evolution. We show that a non-unitary time evolution in the dual quantum theory
corresponds to a violation of the Null Energy Condition (NEC) in the bulk of
the asymptotically AdS spacetime. We find that upon varying the non-Hermitian
coupling the horizon of a bulk AdS black hole shrinks. On the other hand
varying the Hermitian coupling in the presence of a constant non-Hermitian
coupling still violates the NEC but results in a growing horizon. We also show
that by introducing a non-Hermitian gauge field the time evolution can be made
unitary, e.g. the NEC in the bulk is obeyed, and an exactly equivalent purely
Hermitian description can be given.Comment: 32 pages, 9 figure
Far from equilibrium Chiral Magnetic Effect in Strong Magnetic Fields from Holography
We study the real time evolution of the chiral magnetic effect out-ofequilibrium in strongly coupled anomalous field theories. We match the parameters of our model to QCD parameters and draw lessons of possible relevance for the realization of the chiral magnetic effect in heavy ion collisions. In particular, we find an equilibration time of about ~ 0:35 fm/c in presence of the chiral anomaly for plasma temperatures of order T ~ 300 - 400 MeV
Memoria del primer foro sobre logros, problemas y propuestas de los cuerpos académicos de educación y humanidades de la Universidad Autónoma del Estado de México
Motivados por el interés de dialogar nuestras preocupaciones cotidianas en torno al quehacer académico en la Universidad, e impulsados por la inquietud de compartir puntos de vista y apreciaciones acerca de la forma en que organizamos colectivamente el trabajo académico (en especial, de investigación) en los diferentes espacios de especialización disciplinaria e interdisciplinaria en los campos de las Ciencias de la Educación y las Humanidades, asistimos a la convocatoria para reflexionar qué tanto hemos avanzado como verdaderos equipos de trabajo (sobre todo en lo relativo a la investigación) y cuánto aún nos queda por hacer, a fin de coordinar esfuerzos individuales y sumar capacidades en proyectos y actividades comunes a cada cuerpo académico
Subcutaneous anti-COVID-19 hyperimmune immunoglobulin for prevention of disease in asymptomatic individuals with SARS-CoV-2 infection: a double-blind, placebo-controlled, randomised clinical trialResearch in context
Summary: Background: Anti-COVID-19 hyperimmune immunoglobulin (hIG) can provide standardized and controlled antibody content. Data from controlled clinical trials using hIG for the prevention or treatment of COVID-19 outpatients have not been reported. We assessed the safety and efficacy of subcutaneous anti-COVID-19 hyperimmune immunoglobulin 20% (C19-IG20%) compared to placebo in preventing development of symptomatic COVID-19 in asymptomatic individuals with SARS-CoV-2 infection. Methods: We did a multicentre, randomized, double-blind, placebo-controlled trial, in asymptomatic unvaccinated adults (≥18 years of age) with confirmed SARS-CoV-2 infection within 5 days between April 28 and December 27, 2021. Participants were randomly assigned (1:1:1) to receive a blinded subcutaneous infusion of 10 mL with 1 g or 2 g of C19-IG20%, or an equivalent volume of saline as placebo. The primary endpoint was the proportion of participants who remained asymptomatic through day 14 after infusion. Secondary endpoints included the proportion of individuals who required oxygen supplementation, any medically attended visit, hospitalisation, or ICU, and viral load reduction and viral clearance in nasopharyngeal swabs. Safety was assessed as the proportion of patients with adverse events. The trial was terminated early due to a lack of potential benefit in the target population in a planned interim analysis conducted in December 2021. ClinicalTrials.gov registry: NCT04847141. Findings: 461 individuals (mean age 39.6 years [SD 12.8]) were randomized and received the intervention within a mean of 3.1 (SD 1.27) days from a positive SARS-CoV-2 test. In the prespecified modified intention-to-treat analysis that included only participants who received a subcutaneous infusion, the primary outcome occurred in 59.9% (91/152) of participants receiving 1 g C19-IG20%, 64.7% (99/153) receiving 2 g, and 63.5% (99/156) receiving placebo (difference in proportions 1 g C19-IG20% vs. placebo, −3.6%; 95% CI -14.6% to 7.3%, p = 0.53; 2 g C19-IG20% vs placebo, 1.1%; −9.6% to 11.9%, p = 0.85). None of the secondary clinical efficacy endpoints or virological endpoints were significantly different between study groups. Adverse event rate was similar between groups, and no severe or life-threatening adverse events related to investigational product infusion were reported. Interpretation: Our findings suggested that administration of subcutaneous human hyperimmune immunoglobulin C19-IG20% to asymptomatic individuals with SARS-CoV-2 infection was safe but did not prevent development of symptomatic COVID-19. Funding: Grifols