NNLO compatibility between pQCD theory and phenomenology in determination of the b-quark pole and MS¯ running masses

This contribution attempts to determine the [Formula: see text]-quark pole mass [Formula: see text] and [Formula: see text] running mass [Formula: see text] with two different approaches at the next-to-next-to-leading order (NNLO) corrections. At the first approach, we derive a relation between the [Formula: see text]-quark pole mass [Formula: see text] and its [Formula: see text] running mass [Formula: see text] at the NNLO corrections based on the perturbative Quantum Chromo Dynamics (pQCD) predictions. At the second approach, we extract numerical values of the [Formula: see text]-quark pole and [Formula: see text] running masses based on the NNLO phenomenology of H1 and ZEUS Collaborations combined beauty vertex production experimental data. Then we discuss about the compatibility between the pQCD theory results and phenomenology approach in determination of the [Formula: see text]-quark pole and [Formula: see text] running masses at the NNLO corrections. Also, we investigate the role and influence of the [Formula: see text]-quark mass as an extra degree of freedom added to the input parameters of the Standard Model Lagrangian, on the improvement of the uncertainty band of the proton parton distribution functions (PDFs) and particularly on the gluon distribution.

Astrophysics in the Laboratory—The CBM Experiment at FAIR

The future “Facility for Antiproton and Ion Research” (FAIR) is an accelerator-based international center for fundamental and applied research, which presently is under construction in Darmstadt, Germany. An important part of the program is devoted to questions related to astrophysics, including the origin of elements in the universe and the properties of strongly interacting matter under extreme conditions, which are relevant for our understanding of the structure of neutron stars and the dynamics of supernova explosions and neutron star mergers. The Compressed Baryonic Matter (CBM) experiment at FAIR is designed to measure promising observables in high-energy heavy-ion collisions, which are expected to be sensitive to the high-density equation-of-state (EOS) of nuclear matter and to new phases of Quantum Chromo Dynamics (QCD) matter at high densities. The CBM physics program, the relevant observables and the experimental setup will be discussed.

New Canonical and Grand Canonical Density of States Techniques for Finite Density Lattice QCD

We discuss two new density of states approaches for finite density lattice QCD (Quantum Chromo Dynamics). The paper extends a recent presentation of the new techniques based on Wilson fermions, while here, we now discuss and test the case of finite density QCD with staggered fermions. The first of our two approaches is based on the canonical formulation where observables at a fixed net quark number N are obtained as Fourier moments of the vacuum expectation values at imaginary chemical potential θ . We treat the latter as densities that can be computed with the recently developed functional fit approach. The second method is based on a direct grand canonical evaluation after rewriting the QCD partition sum in terms of a suitable pseudo-fermion representation. In this form, the imaginary part of the pseudo-fermion action can be identified and the corresponding density may again be computed with the functional fit approach. We develop the details of the two approaches and discuss some exploratory first tests for the case of free fermions where reference results for assessing the new techniques may be obtained from Fourier transformation.

QCD: The Theory of Strong Interactions

This Chapter is devoted to a concise introduction to Quantum Chromo-Dynamics (QCD), the theory of strong interactions. We start with a general introduction where a broad overview of the strong interactions is presented.

Exploring Cosmic Matter in the Laboratory—The Compressed Baryonic Matter Experiment at FAIR

The Compressed Baryonic Matter (CBM) experiment is one of four scientific pillars of the future Facility for Antiproton and Ion Research (FAIR) in Darmstadt. In collisions between heavy nuclei at FAIR energies, it is expected that the matter in the reaction zone is compressed to more than five times saturation density, corresponding to the density in the core of a massive neutron star. This offers the unique opportunity to study in the laboratory the high-density equation-of-state (EOS) of nuclear matter, and to search for new phases of Quantum Chromo Dynamics (QCD) matter at large baryon-chemical potentials. Promising experimental observables sensitive to the EOS and to possible phase transitions will be discussed, together with a brief description of the CBM experiment.

On the Structure of the Vacuum in Quantum Gravity: A View from the Asymptotic Safety Scenario

Although the Asymptotic Safety scenario is one of the most promising approaches to quantum gravity, little attention has been devoted to the issue of the vacuum state. Higher derivative operators often appear on the ultraviolet critical surface around the non-Gaussian fixed point generating additional degrees of freedom which can render the standard vacuum unstable. When this happens, translation and rotational symmetries can be spontaneously broken and a new set of symmetries can show up at the level of the effective action. In this work, it will be argued that a “kinetic condensate” characterizes the vacuum state of asymptotically safe quadratic gravity theories. If this scenario is realized in the full theory, the vacuum state of gravity is the gravitational analogous to the Savvidy vacuum in Quantum Chromo-Dynamics (QCD).

Hot Dense Matter: Deconfinement and Clustering of Color Sources in Nuclear Collisions

Within the first few microseconds from after the Big Bang, the hot dense matter was in the form of the Quark Gluon Plasm (QGP) consisting of free quarks and gluons. By colliding heavy nuclei at RHIC and LHC at a velocity close to the speed of light, we were able to create the primordial matter and observe the matter after expansion and cooling. In this report we present the thermodynamics and transport coefficients obtained in the framework of clustering of color sources in both hadron-hadron and nucleus-nucleus collisions at RHIC and LHC energies. Multiparticle production at high energies can be described in terms of color strings stretched between the projectile and target. At high string density single strings overlap and form color sources. This addition belongs to the non-perturbative domain of Quantum Chromo Dynamics (QGP) and manifests its most fundamental features. The Schwinger Q E D 2 mechanism produces color neutral q q ¯ pairs when color source strings break. Subsequent hardonization produces the observed hadrons. With growing energy and atomic number of the colliding nuclei the density of strings grows and more color sources form clusters in the transverse plane. At a certain critical density a macroscopic cluster appears, which marks the percolation phase transition. This is the Color String Percolation Model (CSPM). The critical density is identified as the deconfinement transition and happens at the hadronization temperature. The stochastic thermalization in p p and A-A is a consequence of the quantum tunneling through the event horizon introduced by the confining color fields, the Hawking-Unruh effect. The percolation approach within CSPM is successfully used to describe the crossover phase transition in the soft collision region. The same phenomenology when applied to both hadron-hadron and nucleus-nucleus collisions emphasizes the importance of color string density, creating a macroscopic cluster which identifies the connectivity required for a finite droplet of the QGP.