Regular Series


Vol. 47 (2016), No. 7, pp. 1761 – 1997


Physics Beyond the Standard Model in Hadronic Collisions

abstract

The role of hadron colliders in the past discoveries in particle physics and their potential role in the search for physics beyond the Standard Model are briefly reviewed. The emphasis is placed on the production in hadronic collisions of particles that do not interact strongly.


Forward Physics at the LHC: from the Structure of the Pomeron to the Search for \(\gamma \)-induced Resonances

abstract

We describe some of the future measurements to be performed by the CMS, TOTEM and ATLAS collaborations on hard diffraction in order to understand better the structure of the Pomeron. We also describe the prospects concerning the search for quartic \(\gamma \gamma \gamma \gamma \) anomalous couplings and discuss a possible interpretation for the existence of a new particle decaying into two photons at a mass of about 750 GeV.

See Erratum Acta Phys. Pol. B 47, 2117 (2016)


Exotic Baryon Resonances in Photoproduction

abstract

The new exotic pentaquark resonances recently reported by LHCb in the \(J/\psi \,p\) channel are excellent candidates for photoproduction off a proton target. Such photoproduction experiments are a crucial test for confirming that these states are genuine resonances rather than a kinematical artifact. We focus on the interpretation of the heavier narrow state as a deuteron-like bound state of \({\mit \Sigma }_c\) and \(\bar D^*\), and employ vector dominance to estimate its production cross section. The relevant experiments can likely be performed in GlueX and CLAS12 detectors at JLAB which have the relevant photon energies and fluxes. We also perform a calculation for photoproduction of an analogous resonance in the bottomonium sector, predicted to exist in the \({\mit \Upsilon } p\) channel.


Thermodynamic Equilibrium in Relativity: Four-temperature, Killing Vectors and Lie Derivatives

abstract

The main concepts of general relativistic thermodynamics and general relativistic statistical mechanics are reviewed. The main building block of the proper relativistic extension of the classical thermodynamics laws is the four-temperature vector \(\beta \), which plays a major role in the quantum framework and defines a very convenient hydrodynamic frame. The general relativistic thermodynamic equilibrium condition demands \(\beta \) to be a Killing vector field. We show that a remarkable consequence is that all Lie derivatives of all physical observables along the four-temperature flow must then vanish.


Bulk Viscosity in a Plasma of Gribov–Zwanziger Gluons

abstract

We investigate dynamic properties of a plasma whose constituents are confining gluons resulting from the Gribov–Zwanziger quantisation. In a static formulation, this system reproduces qualitatively the pure-glue equation of state and thereby encodes crucial features of the phase transition. The dynamic description proposed in this work allows us to study close-to-equilibrium transport phenomena with the inclusion of confinement effects. In particular, we determine the non-equilibrium behaviour of the interaction measure (trace anomaly) and find the form of the bulk viscosity coefficient. The latter can be used in phenomenological applications to heavy-ion collisions.


Timescales in Heavy-ion Collisions

abstract

The study of high-energy collisions between heavy nuclei is a field unto itself, distinct from nuclear and particle physics. A defining aspect of heavy-ion physics is the importance of a bulk, self-interacting system with a rich space-time substructure. I focus on the issue of timescales in heavy-ion collisions, starting with proof from low-energy collisions that femtoscopy can, indeed, measure very long timescales. I then discuss the relativistic case, where detailed measurements over three orders of magnitude in energy reveal a timescale increase that might be due to a first-order phase transition. I discuss also consistency in evolution timescales as determined from traditional longitudinal sizes and a novel analysis using shape information.

The slowly crawling ants will eat our dreams. Andrzej Bialas, musing on words of Andre Breton Go to the ant, thou sluggard; consider her ways, and be wise. Proverbs vi.6


Fluctuations and the QCD Phase Diagram

abstract

In this contribution, we will discuss how the study of various fluctuation observables may be used to explore the phase diagram of the strong interaction. We will briefly summarize the present study of experimental and theoretical research in this area. We will then discuss various corrections and issues which need to be understood and applied for a meaningful comparison of experimental measurements with theoretical predictions.

See Erratum Acta Phys. Pol. B 47, 2115 (2016)


Production and Correlations of Strange Mesons and Baryons at RHIC and LHC in Hydrokinetic Model

abstract

The recent results on the theoretical analysis of particle production and correlation in relativistic heavy-ion collisions at the LHC and RHIC within the hydrokinetic model (HKM) and its extended version — integrated hydrokinetic model (iHKM) are addressed. The study of strange \(K\) meson spectrum and femtoscopy scales is discussed along with the pion ones for the case of LHC Pb+Pb collisions at \(\sqrt {s_{NN}}=2.76\) TeV. The \(m_{\rm T}\)-dependence of spectra and longitudinal femtoscopy scales at the LHC, obtained in HKM simulations, is compared with the results given by simple analytical formulas including the effective temperature on the hypersurface of maximal particle emission, emission proper time, and transverse flow intensity. The influence of \(K^*(892)\) resonance decays and hadron re-scatterings at the afterburner stage of the collision on the interferometry radii is analyzed. The related problem of \(K^*(892)\) effective identification and reliable yield measurement in view of hadron re-scatterings is also investigated for RHIC and LHC energy cases. The application of the FSI formalism with account for residual correlation effect to modeling of the \(p{\mit \Lambda }\) and \(p{\mit \Xi }\) correlation functions using the source functions calculated in HKM is also considered.


Hadron Correlations at Energies from GeV to TeV

abstract

One of the central issues in High Energy Physics is the close interchange between Theory and Experiment. Ever since I know Andrzej Bialas, I know him as one of the theorists most interested in experimental data. This has naturally led to continuous fruitful contacts. Even though we have been working somehow together since about 1968, we so far have only one single publication in common. This was back in 1969 and it was on means to efficiently study what we then called (exclusive) Multihadron Final States. At that time, this meant 3- or at best 4-particle final states of two-hadron collisions at c.m.s. energies of some 4 GeV (not TeV!). The field of multiparticle dynamics was, in fact, the domain of Polish high-energy physicists. The first of a very successful (and still lasting) series of annual International Symposia on Multiparticle Dynamics was organized in Paris in 1970, but essentially by Polish physicists. Andrzej himself was not attending, but it was him who organized the third in these series in (of course) Zakopane. Since heavy-ion collisions, another field of major interest for Andrzej, will be covered by others, I here will restrict myself mainly to the collisions of two elementary particles.

See Erratum Acta Phys. Pol. B 47, 2113 (2016)


Thermodynamics of van der Waals Fluids with Quantum Statistics

abstract

We consider thermodynamics of the van der Waals fluid of quantum systems. We derive general relations of thermodynamic functions and parameters of any ideal gas and the corresponding van der Waals fluid. This provides unambiguous generalization of the classical van der Waals theory to quantum statistical systems. As an example, we apply the van der Waals fluid with Fermi statistics to characterize the liquid-gas critical point in nuclear matter. We also introduce the Bose–Einstein condensation in the relativistic van der Waals boson gas, and argue that it exhibits two-phase structure separated in space.


Pictures of Particle Production in Proton–Nucleus Collisions

abstract

This work focuses on gluon (jet) production in dilute (proton)–dense (nucleus) collisions. Depending on the frame and gauge, gluon production can be viewed as a freeing of gluons coming from either the proton wave function or from the nucleus wave function. These (apparently) very different pictures must lead to the same result and the purpose of this paper is to see how that happens. The focus is on gluons having \(k_\perp \sim Q_{\rm S}\) or gluons in the scaling region \(k_\perp /Q_{\rm S}\gg 1\). In the McLerran–Venugopalan (MV) model with \(k_\perp \sim Q_{\rm S}\), we are able to derive gluon production in a way that (graphically) manifestly shows \(k_\perp \)-factorization in terms of the number density of gluons in the nuclear wave function. We presume that this picture, and \(k_\perp \)-factorization, continues to hold in the presence of small-\(x\) evolution although we have not been able to explicitly verify this. Our result is in agreement with usual \(k_\perp \)-factorization where the gluon number density of the nucleus does not appear in an explicit way.


Positivity and Unitarity Constraints on Dipole Gluon Distributions

abstract

In the high-energy domain, gluon transverse-momentum dependent distributions in nuclei obey constraints coming from positivity and unitarity of the colorless QCD dipole distributions through Fourier–Bessel transformations. Using mathematical properties of Fourier-positive functions, we investigate the nature of these constraints which apply to dipole model building and formulation.


Charting the Future Frontier(s) of Particle Production

abstract

This short note describes the long collaborative effort between Arizona and Kraków, showing some of the key strangeness signatures of quark–gluon plasma. It further presents an annotated catalog of foundational questions defining the research frontiers which I believe can be addressed in the foreseeable future in the context of relativistic heavy-ion collision experiments. The list includes topics that are specific to the field, and ventures towards the known-to-be-unknown that may have a better chance with ions as compared to elementary interactions.


Andrzej Bialas: Some Short Stories

abstract

In anecdotal fashion, I discuss some of the contributions of Andrzej Bialas to science and the education of young scientists.


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