Configuration Entropy for Quarkonium in a Finite Density Plasma
Nelson R. F. Braga, Rodrigo da Mata
备注：
In this V2 we consider the Differential Configuration Entropy and also provide more details about the temperature and density dependences. 16 pages, 6 figures, 2 tables. Version to appear in Physical Review D. arXiv admin note: text overlap with arXiv:1910.13498
In the recent years many examples appeared in the literature where the configuration entropy (CE), introduced by Gleiser and Stamatopoulos, plays the role of an indicator of stability of physical systems. It was observed that, comparing states of the same system, the lower is the value of the CE, the more stable is the state. In this work we investigate the behaviour of the differential configuration entropy (DCE) , that is appropriate for systems with continuous degrees of freedom, in a new context. We consider quasi-states of quarkonium (a vector meson made of a heavy quark anti-quark pair) inside a plasma at finite density. It is known that the density increases the dissociation effect for quasi-particles inside a plasma. So, increasing the density of a thermal medium corresponds to reducing the stability of the quasi-particles. In order to investigate how this situation is translated in the Configutation Entropy context, we use a recently developed holographic AdS/QCD model for heavy vector mesons. The quasi-normal modes describing the quasi-states are obtained and the corresponding DCE is calculated. We find, for bottomonium and charmonium $1 S$ quasi-states, that the DCE increases with the quark density, or quark chemical potential, of the medium. This result shows that the DCE works again as an indicator of stability, represented in this case by the dissociation effect associated with the density.
Previous research has shown that the peak of the quarkonium entropy at the deconfinement transition would be related to the entropic force which induces the melting of quarkonium. In this article, we study the effect of backreaction on the entropic force in a strongly coupled plasma of adjoint matter. The backreaction covered here comes from the presence of static heavy quarks evenly distributed over such a plasma. It is found that the inclusion of backreaction increases the entropic force thus enhancing the quarkonium dissociation, in accord with the findings of the imaginary potential.
The real-time dissociation of the heavy quarkonium in a strongly coupled boost-invariant non-Abelian plasma relaxing towards equilibrium is analyzed in a holographic framework. The effects driving the plasma out of equilibrium are described by boundary quenching, impulsive variations of the boundary metric. Quarkonium is represented by a classical string with endpoints kept close to the boundary. The evolution of the string profile is computed in the time-dependent geometry, and the dissociation time is evaluated for different configurations with respect to the direction of the plasma expansio…
In the early stages of heavy-ion collisions, the hot QCD matter expands more longitudinally than transversely. This imbalance causes the system to become rapidly colder in the longitudinal direction and a local momentum anisotropy appears. In this paper, we study the heavy-quarkonium spectrum in the presence of a small plasma anisotropy. We work in the framework of pNRQCD at finite temperature. We inspect arrangements of non-relativistic and thermal scales complementary to those considered in the literature. In particular, we consider temperatures larger and Debye masses smaller than the bindi…
Holographic entropy and real-time dynamics of quarkonium dissociation in non-Abelian plasma
在格点量子色动力学中观察到的解除禁闭跃迁处的重夸克对熵峰值表明，该跃迁是由束缚态熵的增加有效驱动的。熵随夸克间距的增大而增大，导致熵力的突现，引起夸克偶素态的离解。由于跃迁点附近的夸克-胶子等离子体是一个强耦合系统，我们利用规范-引力对偶性研究了重夸克偶素的熵及其离解的实时动力学。特别地，我们采用改进的全息QCD模型作为大$N_c$ Yang Mills理论的对偶描述。研究边界上夸克之间的基本弦的动力学，我们发现熵在跃迁点处达到峰值。我们还研究了系统的实时动力学，考虑全息字符串下降的黑洞视界，它平衡。在附近的解除禁闭过渡，解离时间被发现是小于费米，这表明熵破坏是在这个温度区域的主要解离机制。
Recent investigations show that the thermal spectral function of heavy $ {b \bar b } $ and $ {c \bar c} $ vector mesons can be described using holography. These studies consider a bottom up model that captures the heavy flavour spectroscopy of masses and decay constants in the vacuum and is consistently extended to finite temperature. The corresponding spectral functions provide a picture of the dissociation process in terms of the decrease of the quasi-state peaks with temperature. Another related tool that provides important information about the thermal behaviour is the analysis of the quas…
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Heavy vector mesons detected after a heavy ion collision are important sources of information about the quark gluon plasma. The fraction of such particles that survive the plasma phase and reach the detectors is related to the dissociation degree inside the thermal medium. A consistent picture for the thermal behavior of charmonium and bottomonium quasi-states in a thermal medium was obtained recently using a holographic bottom up model. This model captures the heavy flavour spectroscopy of masses and decay constants in the vacuum (zero temperature) and is consistently extended to finite tempe…
We continue the study of a recently constructed holographic QCD model supplemented with magnetic field. We consider the holographic dual of a quark, anti-quark pair and investigate its entropy beyond the deconfinement phase transition in terms of interquark distance, temperature and magnetic field. We obtain a clear magnetic field dependence in the strongly decreasing entropy near deconfinement and in the entropy variation for growing interquark separation. We uncover various supporting evidences for inverse magnetic catalysis. The emergent entropic force is found to become stronger with magne…
We use gauge/string duality to model a heavy quark-antiquark pair in a color singlet moving through a thermal plasma. In particular, we explore the effect of velocity on the string tension and Debye screening mass. Then we apply the results to the analysis of heavy quarkonium bound states. With some assumptions, we estimate the characteristic size of quarkonium and its dissociation temperature.
We perform a comprehensive study of the time evolution of heavy-quarkonium states in an expanding hot QCD medium by implementing effective field theory techniques in the framework of open quantum systems. The formalism incorporates quarkonium production and its subsequent evolution in the fireball including quarkonium dissociation and recombination. We consider a fireball with a local temperature that is much smaller than the inverse size of the quarkonium and much larger than its binding energy. The calculation is performed at an accuracy that is leading-order in the heavy-quark density expan…
There are strong indications that ultra-relativistic heavy ion collisions, produced in accelarators, lead to the formation of a new state of matter: the quark gluon plasma (QGP). This deconfined QCD matter is expected to exist just for very short times after the collision. All the information one can get about the plasma is obtained from the particles that reach the detectors. Among them, heavy vector mesons are particularly important. The abundance of $ c {\bar c}$ and $b {\bar b}$ states produced in a heavy ion collision is a source of information about the plasma. In contrast to the light m…
