abstract

These lectures advocate the idea that quantum entanglement provides a unifying foundation for both statistical physics and high-energy interactions. I argue that, at sufficiently long times or high energies, most quantum systems approach a Maximal Entanglement Limit (MEL) in which phases of quantum states become unobservable, reduced density matrices acquire a thermal form, and probabilistic descriptions emerge without invoking ergodicity or classical randomness. Within this framework, the emergence of probabilistic parton model, thermalization in the break-up of confining strings and in high-energy collisions, and the universal small-\(x\) behavior of structure functions arise as direct consequences of entanglement and geometry of high-dimensional Hilbert space.

abstract

The phase diagram of QCD at finite temperature and density is discussed. Large number of quark colors, \(N_{c} \gg 1\), is used to explain generic features of the phase diagram. For temperatures below \(T \le 160\) MeV at zero baryon number density, the three-dimensional string model is shown to describe the thermodynamics of QCD, as well as, the integrated spectrum of non-Goldstone mesons and glueballs. The lowest mass state in the spectrum of the open and closed string is treated separately due to the tachyon problem of string theory. This is with no undetermined free parameters. It is argued that there are at least three phases at zero baryon number density characterized by the \(N_{c}\) dependence of extensive thermodynamic quantities. It is also argued that the intermediate phase has restored chiral symmetry. At high baryon number density and low temperature, again there are three phases. A Quarkyonic phase, with energy density of order \(N_{c}\), is distinguished from its counterpart at low baryon density and temperature by its chiral properties.

abstract

In this manuscript, we show some interesting aspects of physics of interface. These are related to the phenomena occurring in the interior of neutron stars.

abstract

We provide an elementary pedagogical introduction to some basic concepts and techniques of soft (or Sudakov) resummation, specifically in QCD, paying particular attention to simple but useful tricks of the trade. We briefly review collinear (Altarelli–Parisi) and infrared (eikonal) factorization, cancellation of infrared singularities, and factorization of mass singularities. We recall basic concepts on renormalization group invariance and the solution of renormalization group equations. We then show how threshold resummation can be derived from a renormalization group argument following from the cancellation of infrared singularities. We discuss various equivalent forms of the resummed result, and we briefly present transverse momentum resummation.

abstract

In this article, ultraperipheral collisions of nuclei are discussed with focus on the probes of nuclear structure. Calculations for the open charm production in UPC collisions of PbPb at the LHC are described and compared with the experimental data from the CMS experiment.