Nuclear Theory·nucl-th

Wednesday·December 3, 2014

9 papers—2 primary·7 cross-listed

03
Excitation function of elastic $pp$ scattering from a unitarily extended Bialas-Bzdak model
F. Nemes🇨🇭 · T. Csörgő🇭🇺 · M. Csanád🇭🇺
The Bialas-Bzdak model of elastic proton-proton scattering assumes a purely imaginary forward scattering amplitude, which consequently vanishes at the diffractive minima. We extended the model to arbitrarily large real parts in a way that constraints from unitarity are satisfied. The resulting model is able to describe elastic $pp$ scattering not only at the lower ISR energies but also at $s =$ 7 TeV in a statistically acceptable manner, both in the diffractive cone and in the region of the first diffractive minimum. The total cross-section as well as the differential cross-section of elastic proton-proton scattering is predicted for the future LHC energies of $s =$ 8, 13, 14, 15 TeV and also to 28 TeV. A non-trivial, significantly non-exponential feature of the differential cross-section of elastic proton-proton scattering is analyzed and the excitation function of the non-exponential behavior is predicted. The excitation function of the shadow profiles is discussed and related to saturation at small impact parameters.
↳ hep-phnucl-th0 citations
04
QCD at nonzero chemical potential: recent progress on the lattice
Gert Aarts🇬🇧 · Felipe Attanasio🇬🇧 · Benjamin Jäger🇬🇧 · Erhard Seiler🇩🇪 · Denes Sexty🇩🇪 · Ion-Olimpiu Stamatescu🇩🇪
We summarise recent progress in simulating QCD at nonzero baryon density using complex Langevin dynamics. After a brief outline of the main idea, we discuss gauge cooling as a means to control the evolution. Subsequently we present a status report for heavy dense QCD and its phase structure, full QCD with staggered quarks, and full QCD with Wilson quarks, both directly and using the hopping parameter expansion to all orders.
↳ hep-lathep-phnucl-thAIP Conf.Proc.(2016)·31 citations
05
Ward identities, $B \to V$ transition form factors and applications
M.Ali Paracha🇧🇷 · Bruno El-Bennich🇧🇷 · M.Jamil Aslam🇵🇰 · Ishtiaq Ahmed🇧🇷
Long distance effects are studied in the rare exclusive semileptonic $B_{(d, s)} \to V ℓ^{+} ℓ^{-}$ decays, where $V$ denotes a $K^{*}$ or $ϕ$ meson. The form factors, which describe the meson transition amplitudes in the effective Hamiltonian approach, are calculated by means of Ward identities, experimental constraints and extrapolated within a general vector meson dominance framework. These form factors are then compared to the ones obtained in Lattice QCD simulations, with Light Cone Sum Rules and a Dyson-Schwinger equation approach. Additionally, the $B_{d} \to K^{*} ℓ^{+} ℓ^{-}$ and $B_{s} \to ϕ ℓ^{+} ℓ^{-}$ branching ratios are computed and the differential branching fractions are given as a function of the squared-momentum transfer.
↳ hep-phhep-exhep-latnucl-thJ.Phys.Conf.Ser.(2015)·5 citations
06
The Non-Classical Boltzmann Equation, and Diffusion-Based Approximations to the Boltzmann Equation
Martin Frank · Kai Krycki · Edward W. Larsen · Richard Vasques
We show that several diffusion-based approximations (classical diffusion or SP1, SP2, SP3) to the linear Boltzmann equation can (for an infinite, homogeneous medium) be represented exactly by a non-classical transport equation. As a consequence, we indicate a method to solve diffusion-based approximations to the Boltzmann equation via Monte Carlo, with only statistical errors - no truncation errors.
↳ math-phmath.MPnucl-thSIAM J.Appl.Math.(2015)·5 citations
07
Transport properties of the hot and dense sQGP
Hamza Berrehrah🇩🇪 · Elena Bratkovskaya🇩🇪 · Wolfgang Cassing🇩🇪 · Rudy Marty🇩🇪
The transport properties of the quark gluon plasma (QGP) are studied in a QCD medium at finite temperature and chemical potential. We calculate the shear viscosity $η (T, μ_{q})$ and the electric conductivity $σ_{e} (T, μ_{q})$ for a system of interacting massive and broad quasi-particles as described by the dynamical quasi-particle model "DQPM" at finite temperature $T$ and quark chemical potential $μ_{q}$ within the relaxation time approximation. Our results are in a good agreement with lattice QCD at finite temperature and show clearly the increase of the transport coefficients with increasing $T$ and $μ_{q}$ . Our results provide the basic ingredients for the study of the hot and dense matter in the Beam Energy Scan (BES) at RHIC and CBM at FAIR.
↳ hep-phnucl-thJ.Phys.Conf.Ser.(2015)·14 citations
08
Polyakov-loop suppression of colored states in a quark-meson-diquark plasma
D. Blaschke🇷🇺 · A. Dubinin🇵🇱 · M. Buballa🇩🇪
A quark-meson-diquark plasma is considered within the PNJL model for dynamical chiral symmetry breaking and restoration in quark matter. Based on a generalized Beth-Uhlenbeck approach to mesons and diquarks we present the thermodynamics of this system including the Mott dissociation of mesons and diquarks at finite temperature. A striking result is the suppression of the diquark abundance below the chiral restoration temperature by the coupling to the Polyakov loop, because of their color degree of freedom. This is understood in close analogy to the suppression of quark distributions by the same mechanism. Mesons as color singlets are unaffected by the Polyakov-loop suppression. At temperatures above the chiral restoration mesons and diquarks are both suppressed due to the Mott effect, whereby the positive resonance contribution to the pressure is largely compensated by the negative scattering contribution in accordance with the Levinson theorem.
↳ hep-phnucl-thPRD(2015)·26 citations
09
From Quarks and Gluons to Hadrons: Chiral Symmetry Breaking in Dynamical QCD
Jens Braun🇩🇪 · Leonard Fister🇫🇷 · Jan M. Pawlowski🇩🇪 · Fabian Rennecke🇩🇪
We present an analysis of the dynamics of two-flavour QCD in the vacuum. Special attention is payed to the transition from the high energy quark-gluon regime to the low energy regime governed by hadron dynamics. This is done within a functional renormalisation group approach to QCD amended by dynamical hadronisation techniques. The latter allow us to describe conveniently the transition from the perturbative high-energy regime to the nonperturbative low-energy limit without suffering from a fine-tuning of model parameters. In the present work, we apply these techniques to two-flavour QCD with physical quark masses and show how the dynamics of the dominant low-energy degrees of freedom emerge from the underlying quark-gluon dynamics.
↳ hep-phhep-thnucl-thPRD(2016)·241 citations

Affiliations

first authorsco-authorsvia INSPIRE

Excitation function of elastic pp scattering from a unitarily extended Bialas-Bzdak model

QCD at nonzero chemical potential: recent progress on the lattice

Ward identities, B→V transition form factors and applications

The Non-Classical Boltzmann Equation, and Diffusion-Based Approximations to the Boltzmann Equation

Transport properties of the hot and dense sQGP

Polyakov-loop suppression of colored states in a quark-meson-diquark plasma

From Quarks and Gluons to Hadrons: Chiral Symmetry Breaking in Dynamical QCD

Affiliations

Excitation function of elastic $pp$ scattering from a unitarily extended Bialas-Bzdak model

Ward identities, $B \to V$ transition form factors and applications