Colliding localized, lumpy holographic shocks with a granular nuclear structure

We apply a recent and simple technique which speeds up the calculation of localized collisions in holography to study more realistic models of heavy ion collisions via the gauge/gravity duality. The initial data takes into account the lumpy nuclear structure of real heavy ions and the projectiles' aspect ratio mimics the Lorentz contraction of nuclei during RHIC collisions. At the hydrodynamization time of the central region of the quark gluon plasma developed during the collision, we find that most of the vorticity three vector's absolute value is deposited far away from the hydrodynamized part of the plasma. Only the relativistic corrections to the thermal vorticity in the hydrodynamized region are non-negligible. We compare the transverse flow after the collision determined in this work with previous results, without granular initial conditions and determine the proper energy density and fluid velocity in a hydrodynamized subregion of the plasma.Comment: 25 pages, 13 figures, figures 7,8,11,12 were added, introduction, result section and conclusion were expanded, typos were fixe

Quasinormal modes of magnetic black branes at finite ’t Hooft coupling

The aim of this work is to extend the knowledge about Quasinormal Modes (QNMs) and the equilibration of strongly coupled systems, specifically of a quark gluon plasma (which we consider to be in a strong magnetic background field) by using the duality between N = 4 Super Yang-Mills (SYM) theory and type IIb Super Gravity (SUGRA) and including higher derivative corrections. The behaviour of the equilibrating system can be seen as the response of the system to tiny excitations. A quark gluon plasma in a strong magnetic background field, as produced for very short times during an actual heavy ion collision, is described holographically by certain metric solutions to 5D Einstein-Maxwell- (Chern-Simons) theory, which can be obtained from type IIb SUGRA. We are going to compute higher derivative corrections to this metric and consider alpha ' (3) corrections to tensor- quasinormal modes in this background geometry. We find indications for a strong influence of the magnetic background field on the equilibration behaviour also and especially when we include higher derivative corrections

Finite 't Hooft coupling corrections and shockwave collisions in AdS/CFT

In the first part of this work we compute finite ’t Hooft coupling corrections to observables related to charged quantities in a strongly coupled $\mathcal{N}=4$ supersymmetric Yang-Mills plasma. We correct errors in the literature regarding the finite 't Hooft coupling corrected equations of motion of gauge fields in AdS/CFT. As a consequence the finite 't Hooft coupling corrections to the observables considered, including the conductivity, quasinormal mode frequencies, in and off equilibrium spectral density and photoemission rates, become much smaller, suggesting that infinite coupling results obtained within AdS/CFT are little modified for the real QCD coupling strength. In addition we study higher derivative corrections to the magnetic black brane geometry, to investigate a quark gluon plasma in a strong magnetic background field at finite coupling. Finite 't Hooft coupling terms to the lowest tensor quasinormal mode in this geometry are determined, shedding light on the equilibration time of a quark gluon plasma in the presence of a magnetic field while including higher derivative terms. Concluding the analysis of AdS/CFT at finite coupling we present a higher order resummation technique, that suggests that in general observables computed from AdS/CFT are only modestly modified at coupling strengths, which are realistic for hot QCD. In the second part of this thesis we simulate peripheral heavy ion collisions by computing asymmetric shockwave collisions in maximally supersymmetric Yang-Mills theory via their dual gravitational formulation. We found the post-collision hydrodynamic flow to be well described by appropriate means of the results of symmetric shock collisions. With the universal model for the hydrodynamic flow produced by asymmetric planar collisions one can construct, quantitatively, non-planar, non-central collisions of highly Lorentz contracted projectiles without the need for computing, holographically, collisions of finite size projectiles with very large aspect ratios, given that transverse gradients are small. We confirmed that the hydrodynamization time only negligibly depends on the shock-widths and asymmetry of the shocks. Thus, also for peripheral collisions it merely depends on the energy density per transverse unit area, justifying assumptions made in hydro simulations so far

Holographic Kolmogorov-Sinai entropy and the quantum Lyapunov spectrum

In classical chaotic systems the entropy, averaged over initial phase space distributions, follows a universal behavior. While approaching thermal equilibrium it passes through a stage where it grows linearly, while the growth rate, the Kolmogorov-Sinai entropy (rate), is given by the sum over all positive Lyapunov exponents. A natural question is whether a similar relation is valid for quantum systems. We argue that the Maldacena-Shenker-Stanford bound on quantum Lyapunov exponents implies that the upper bound on the growth rate of the entropy, averaged over states in Hilbert space that evolve towards a thermal state with temperature T, should be given by πT times the thermal state’s von Neumann entropy. Strongly coupled, large N theories with black hole duals should saturate the bound. To test this we study a large number of isotropization processes of random, spatially homogeneous, far from equilibrium initial states in large N, N = 4 Super Yang Mills theory at strong coupling and compute the ensemble averaged growth rate of the dual black hole’s apparent horizon area. We find both an analogous behavior as in classical chaotic systems and numerical evidence that the conjectured bound on averaged entropy growth is saturated granted that the Lyapunov exponents are degenerate and given by λi = ±2πT. This fits to the behavior of classical systems with plus/minus symmetric Lyapunov spectra, a symmetry which implies the validity of Liouville’s theorem

Äärellisen kytkennän korjauksia kuuman QCD:n holografisiin ennusteisiin

Finite ’t Hooft coupling corrections to multiple physical observables in strongly coupled N=4 supersymmetric Yang-Mills plasma are examined, in an attempt to assess the stability of the expansion in inverse powers of the ’t Hooft coupling λ. Observables considered include thermodynamic quantities, transport coefficients, and quasinormal mode frequencies. Although large λ expansions for quasinormal mode frequencies are notably less well behaved than the expansions of other quantities, we find that a partial resummation of higher order corrections can significantly reduce the sensitivity of the results to the value of λ.Finite 't Hooft coupling corrections to multiple physical observables in strongly coupled N = 4 supersymmetric Yang-Mills plasma are examined, in an attempt to assess the stability of the expansion in inverse powers of the 't Hooft coupling lambda. Observables considered include thermodynamic quantities, transport coefficients, and quasinormal mode frequencies. Although large lambda expansions for quasinormal mode frequencies are notably less well behaved than the expansions of other quantities, we find that a partial resummation of higher order corrections can significantly reduce the sensitivity of the results to the value of lambda.Peer reviewe

Asymmetric shockwave collisions in AdS5

Collisions of asymmetric planar shocks in maximally supersymmetric Yang-Mills theory are studied via their dual gravitational formulation in asymptotically anti-de Sitter spacetime. The post-collision hydrodynamic flow is found to be very well described by appropriate means of the results of symmetric shock collisions. This study extends, to asymmetric collisions, previous work of Chesler, Kilbertus, and van der Schee examining the special case of symmetric collisions [1]. Given the universal description of hydrodynamic flow produced by asymmetric planar collisions one can model, quantitatively, non-planar, non-central collisions of highly Lorentz contracted projectiles without the need for computing, holographically, collisions of finite size projectiles with very large aspect ratios. This paper also contains a pedagogical description of the computational methods and software used to compute shockwave collisions using pseudo-spectral methods, supplementing the earlier overview of Chesler and Yaffe [2]

Phenomenological implications of asymmetric AdS5 shock wave collision studies for heavy ion physics

This paper discusses possible phenomenological implications for p + A and A + A collisions of the results of recent numerical AdS/CFT calculations examining asymmetric collisions of planar shocks. In view of the extreme Lorentz contraction, we model highly relativistic heavy ion collisions as a superposition of collisions between many near-independent transverse "pixels" with differing incident longitudinal momenta. It was found that also for asymmetric collisions the hydrodynamization time is in good approximation a proper time, just like for symmetric collisions, depending on the geometric mean of the longitudinally integrated energy densities of the incident projectiles. For realistic collisions with fluctuations in the initial energy densities, these results imply a substantial increase in the hydrodynamization time for highly asymmetric pixels. However, even in this case the local hydrodynamization time still is significantly smaller than perturbative results for the thermalization time

056 Mutli-dimensional prevention program after acute coronary syndrome (ELIPS)

BackgroundGuidelines recommend pharmacologic and lifestyle interventions to reduce recurrence of events in patients with coronary and other atherosclerotic vascular disease. Based on our systematic review of tested interventions, we developed the ELIPS program, a multidimensional secondary prevention program targeting multiple cardiovascular risk factors for patients after an acute coronary syndrome (ACS). This programme targets an increase in prescription rates by physicians and/or long term medication adherence by patients.ObjectivesTo demonstrate the effectiveness of the ELIPS programme (Multi-dimEnsionaL preventIon Program after Acute coronary Syndrome), which aims at improving quality of care of patients admitted to hospital with ACS in the Swiss setting.MethodsA total of 2400 patients will be prospectively included in a multicenter study before and after the implementation of the ELIPS program with a follow-up of 12 months. The primary outcome is a composite of death from any cause, myocardial infarction, documented unstable angina requiring rehospitalization, revascularization (performed at least 30 days after randomization), and stroke. The secondary endpoints are the isolated endpoints of the primary endpoint as well as cardiovascular mortality, and surrogate outcomes such as cardiovascular risk factor control at follow-up.Expected resultsTo demonstrate the benefits of the ELIPS program on recurrence rate of cardiovascular events. These results will certainly lead to a generalization of such programs in the field of atherosclerosis