اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدCan a closed critical surface in a quark-gluon plasma serve as a model for the behavior of quantum gravity near to an event horizon?
78
0
0.0
(
0
)
تأليف
George Chapline
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Time stands still at a quantum critical point in the sense that correlation functions near to the critical point are approximately independent of frequency. In the case of a quantum liquid this would imply that classical hydrodynamics breaks down near to the critical point, revealing the underlying quantum degrees of freedom. An opportunity to see this effect for the first time in the laboratory may be provided by relativistic heavy ion collisions that are tuned so that the quark-gluon plasma passes through its critical point forming a closed critical surface. In this note we point out that in certain kinds of quantum fluids the temperature of a spherical critical surface will be proportional to (radius)-1 and the entropy inside the surface will be close to the Bekenstein bound. In these cases the breakdown in hydrodynamics near to the critical point might serve as a model for the behavior of quantum gravity near to an event horizon. Such a possibility is a fortiori notable because general relativity predicts that nothing should happen at an event horizon.
قيم البحث
اقرأ أيضاً
We prove the existence of general relativistic perfect fluid black hole solutions, and demonstrate the phenomenon for the $P=wrho$ class of equations of state. While admitting a local time-like Killing vector on the event horizon itself, the various
black hole configurations are necessarily time dependent (thereby avoiding a well known no-go theorem) away from the horizon. Consistently, Hawkings imaginary time periodicity is globally manifest on the entire spacetime manifold.
Photons are a penetrating probe of the hot medium formed in heavy-ion collisions, but they are emitted from all collision stages. At photon energies below 2-3 GeV, the measured photon spectra are approximately exponential and can be characterized by
their inverse logarithmic slope, often called effective temperature $T_mathrm{eff}$. Modelling the evolution of the radiating medium hydrodynamically, we analyze the factors controlling the value of $T_mathrm{eff}$ and how it is related to the evolving true temperature $T$ of the fireball. We find that at RHIC and LHC energies most photons are emitted from fireball regions with $T{,sim,}T_mathrm{c}$ near the quark-hadron phase transition, but that their effective temperature is significantly enhanced by strong radial flow. Although a very hot, high pressure early collision stage is required for generating this radial flow, we demonstrate that the experimentally measured large effective photon temperatures $T_mathrm{eff}{,>,}T_mathrm{c}$, taken alone, do not prove that any electromagnetic radiation was actually emitted from regions with true temperatures well above $T_mathrm{c}$. We explore tools that can help to provide additional evidence for the relative weight of photon emission from the early quark-gluon and late hadronic phases. We find that the recently measured centrality dependence of the total thermal photon yield requires a larger contribution from late emission than presently encoded in our hydrodynamic model.
In this paper we study the real-time evolution of heavy quarkonium in the quark-gluon plasma (QGP) on the basis of the open quantum systems approach. In particular, we shed light on how quantum dissipation affects the dynamics of the relative motion
of the quarkonium state over time. To this end we present a novel non-equilibrium master equation for the relative motion of quarkonium in a medium, starting from Lindblad operators derived systematically from quantum field theory. In order to implement the corresponding dynamics, we deploy the well established quantum state diffusion method. In turn we reveal how the full quantum evolution can be cast in the form of a stochastic non-linear Schrodinger equation. This for the first time provides a direct link from quantum chromodynamics (QCD) to phenomenological models based on non-linear Schrodinger equations. Proof of principle simulations in one-dimension show that dissipative effects indeed allow the relative motion of the constituent quarks in a quarkonium at rest to thermalize. Dissipation turns out to be relevant already at early times well within the QGP lifetime in relativistic heavy ion collisions.
The quark-gluon plasma, possibly created in ultrarelativistic heavy-ion collisions, is a strongly interacting many-body parton system. By comparison with strongly coupled electromagnetic plasmas (classical and non-relativistic) it is concluded that t
he quark-gluon plasma could be in the liquid phase. As an example for a strongly coupled plasma, complex plasmas, which show liquid and even solid phases, are discussed briefly. Furthermore, methods based on correlation functions for confirming and investigating the quark-gluon-plasma liquid are presented. Finally, consequences of the strong coupling, in particular a cross section enhancement in accordance with experimental observations at RHIC, are discussed.
Four-dimensional random geometries can be generated by statistical models with rank-4 tensors as random variables. These are dual to discrete building blocks of random geometries. We discover a potential candidate for a continuum limit in such a mode
l by employing background-independent coarse-graining techniques where the tensor size serves as a pre-geometric notion of scale. A fixed point candidate which features two relevant directions is found. The possible relevance of this result in view of universal results for quantum gravity and a potential connection to the asymptotic-safety program is discussed.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
