Nuclear Theory·nucl-th

Friday·October 30, 2015

7 papers—2 primary·5 cross-listed

03
Glueball Decay in the Witten-Sakai-Sugimoto Model and Finite Quark Masses
Frederic Brünner🇦🇹 · Anton Rebhan🇦🇹
We discuss recent results on the calculation of glueball decay rates in the Witten-Sakai-Sugimoto model, which favor the $f_{0} (1710)$ meson as a glueball candidate. The flavor asymmetric decay of $f_{0} (1710)$ is frequently attributed to a putative chiral suppression in glueball decays, which is however questionable in view of the large constituent quark masses induced by chiral symmetry breaking. We find that this can be explained by what we call nonchiral enhancement when finite quark masses are included in the holographic model, with good quantitative agreement with experimental data for $f_{0} (1710)$ . Assuming the latter to indeed be a nearly pure glueball, the model makes essentially parameter-free and thus falsifiable predictions for its decay rates involving vector mesons and an upper limit on the $η η^{'}$ decay rate.
↳ hep-phhep-thnucl-thPoS(2015)·2 citations
04
Saturation and geometrical scaling -- from small $x$ deep inelastic ep scattering to high energy proton-proton and heavy ion collisions
Michal Praszalowicz🇵🇱
Gluon distributions of colliding hadrons saturate as a result of the non-linear evolution equations of QCD. As a consequence there exists the so called saturation momentum, which is related to the gluon density per unit rapidity per transverse area. When saturation momentum is the only scale for physical processes, different observables exhibit geometrical scaling (GS). We show a number of examples of GS and its violation in different reactions.
↳ hep-phnucl-thPoS(2015)·2 citations
05
Chiral Symmetry transition in the Linear Sigma Model with quarks: Counting effective QCD degrees of freedom from low to high temperature
Alejandro Ayala🇿🇦 · Jorge David Castano-Yepes🇲🇽 · J. J. Cobos-Martinez🇲🇽 · Saul Hernandez-Ortiz🇲🇽 · Ana Julia Mizher🇲🇽 · Alfredo Raya🇲🇽
We use the linear sigma model coupled to quarks, together with a plausible location of the critical end point (CEP), to study the chiral symmetry transition in the QCD phase diagram. We compute the effective potential at finite temperature and density up to the contribution of the ring diagrams, both in the low and high temperature limits, and use it to compute the pressure and the position of the CEP. In the high temperature regime, by comparing to results from extrapolated lattice data, we determine the model coupling constants. Demanding that the CEP remains in the same location when described in the high temperature limit, we determine again the couplings and the pressure for the low temperature regime. We show that this procedure gives an average description of the lattice QCD results for the pressure and that the change from the low to the high temperature domains in this quantity can be attributed to the change in the coupling constants which in turn we link to the change in the effective degrees of freedom.
↳ hep-phhep-latnucl-thInt.J.Mod.Phys.A(2016)·10 citations
06
Compositeness of the Delta(1232) resonance in pi N scattering
Takayasu Sekihara (Osaka U., Res. Ctr. Nucl. Phys.)🇯🇵 · Takashi Arai (KEK, Tsukuba)🇯🇵 · Junko Yamagata-Sekihara (Nat. Inst. Tech., Oshima Coll.)🇯🇵 · Shigehiro Yasui (Tokyo Inst. Tech.)🇯🇵
We evaluate the $π N$ compositeness of the $Δ (1232)$ resonance so as to clarify the internal structure of $Δ (1232)$ in terms of the $π N$ component. Here the compositeness is defined as contributions from two-body wave functions to the normalization of the total wave function and is extracted from the $π N$ scattering amplitude. In this study we employ the chiral unitary approach with the interaction up to the next-to-leading order plus a bare $Δ$ term in chiral perturbation theory and describe $Δ (1232)$ in an elastic $π N$ scattering. Fitting the $π N$ scattering amplitude to the solution of the partial wave analysis, we obtain a large real part of the $π N$ compositeness for $Δ (1232)$ comparable to unity and non-negligible imaginary part as well, with which we reconfirm the result in the previous study on the $π N$ compositeness for $Δ (1232)$ .
↳ hep-phhep-exnucl-exnucl-thJPS Conf.Proc.(2016)·2 citations
07
Recent developments in heavy flavor probes in lattice QCD
Anthony Francis🇨🇦
The analysis of heavy flavor lattice correlation functions to obtain insights into transport phenomena and bound state dissociation patterns is a difficult and interesting challenge from the point of view of lattice QCD spectroscopy. In this contribution to "Hard Probes 2015", the recent developments and advances from different lattice efforts to determine the relevant spectral properties will be reviewed and discussed. The difficulties underlying this line of research will be highlighted and the obtained results assessed. Among others, results on the dissociation of charm systems and bottomonia, as well as the diffusion of heavy quarks will be addressed.
↳ hep-phhep-latnucl-thNucl.Part.Phys.Proc.(2016)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Glueball Decay in the Witten-Sakai-Sugimoto Model and Finite Quark Masses

Saturation and geometrical scaling -- from small x deep inelastic ep scattering to high energy proton-proton and heavy ion collisions

Chiral Symmetry transition in the Linear Sigma Model with quarks: Counting effective QCD degrees of freedom from low to high temperature

Compositeness of the Delta(1232) resonance in pi N scattering

Recent developments in heavy flavor probes in lattice QCD

Affiliations

Saturation and geometrical scaling -- from small $x$ deep inelastic ep scattering to high energy proton-proton and heavy ion collisions