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.

abstract

The internal structure of hadrons is characterized by form factors which correspond to matrix elements of currents. Among those, the stress-energy-momentum tensor is a universally conserved quantity providing the gravitational form factors, from which mechanical properties may be derived via the response to the space-time fluctuations. They have received much attention due to their role as moments of the Generalized Parton Distributions, where the stress-energy-momentum tensor couples to two photons, and more recently, due to the explicit lattice QCD determination for the pion and nucleon. In these lectures, we attempt a pedagogical review of the topic from a purely hadronic point of view, based on the notion of dispersion relations, meson dominance, and parton–hadron duality. We show that despite the overwhelming simplicity of the approach, a rather successful description of the lattice QCD data is achieved.

abstract

Where do gauge symmetries come from? This article develops the idea that the Standard Model might be emergent, with its gauge symmetries dissolving in some phase transition deep in the ultraviolet. The (meta)stability of the Higgs vacuum may be pointing to some new critical phenomena at very high energy scales, with the Higgs connecting physics at LHC laboratory energies to that in the deep ultraviolet. In the emergence scenario, the dark energy scale comes out similar to the size of light Majorana neutrino masses. These two quantities appear at the same order in a low-energy expansion in inverse powers of the scale of emergence, about \(10^{16}\) GeV. Dark matter candidates include axions and phonon-like excitations of degrees of freedom above the scale of emergence. Possible tests of these ideas involve neutrinos as well as gravitational-waves-related signals from the early Universe observables, which are sensitive to physics at very high energy scales.