Nuclear Theory·nucl-th

Friday·September 16, 2016

9 papers—4 primary·5 cross-listed

05
Extraction of the proton charge radius from experiments
N. G. Kelkar🇨🇴 · T. Mart🇮🇩 · M. Nowakowski🇨🇴
Static properties of hadrons such as their radii and other moments of the electric and magnetic distributions can only be extracted using theoretical methods and not directly measured from experiments. As a result, discrepancies between the extracted values from different precision measurements can exist. The proton charge radius, $r_{p}$ , which is either extracted from electron proton elastic scattering data or from hydrogen atom spectroscopy seems to be no exception. The value $r_{p} = 0.84087 (39)$ fm extracted from muonic hydrogen spectroscopy is about 4% smaller than that obtained from electron proton scattering or standard hydrogen spectroscopy. The resolution of this so called proton radius puzzle has been attempted in many different ways over the past six years. The present article reviews these attempts with a focus on the methods of extracting the radius.
↳ hep-phnucl-thMakara Journal of Science, 20/3 (2016), 1…·3 citations
06
Anisotropic flow measurements in Pb--Pb collisions at 5.02 TeV with ALICE
You Zhou🇩🇰
Anisotropic flow is a sensitive probe of the initial conditions and the transport properties of the Quark Gluon Plasma (QGP) produced in heavy-ion collisions. In these proceedings, we present the first results of elliptic ( $v_{2}$ ), triangular ( $v_{3}$ ) and quadrangular flow ( $v_{4}$ ) of charged particles in Pb--Pb collisions at $s_{_{NN}} =$ 5.02 TeV with the ALICE detector. In addition, the comparison of experimental measurements to various theoretical calculations will be discussed. This provides a unique opportunity to test the validity of the hydrodynamic picture and discriminates between various possibilities for the temperature dependence of shear viscosity to entropy density ratio of the produced QGP.
↳ nucl-exnucl-thJ.Phys.Conf.Ser.(2017)·2 citations
07
Chiral medium produced by parallel electric and magnetic fields
Marco Ruggieri🇨🇳 · Guang Xiong Peng🇨🇳 · Maxim Chernodub🇫🇷
We compute (pseudo)critical temperature, $T_{c}$ , of chiral symmetry restoration for quark matter in the background of parallel electric and magnetic fields. This field configuration leads to the production of a chiral medium on a time scale $τ$ , characterized by a nonvanishing value of the chiral density that equilibrates due to microscopic processes in the thermal bath. We estimate the relaxation time $τ$ to be about $\approx 0.1 - 1$ fm/c around the chiral crossover; then we compute the effect of the fields and of the chiral medium on~ $T_{c}$ . We find $T_{c}$ to be lowered by the external fields in the chiral medium.
↳ hep-phhep-latnucl-thEPJ Web Conf.(2016)·10 citations
08
Model prediction for temperature dependence of meson pole masses from lattice QCD results on meson screening masses
Masahiro Ishii🇯🇵 · Hiroaki Kouno🇯🇵 · Masanobu Yahiro🇯🇵
We propose a practical effective model by introducing temperature ( $T$ ) dependence to the coupling strengths of four-quark and six-quark Kobayashi-Maskawa-'t Hooft interactions in the 2+1 flavor Polyakov-loop extended Nambu-Jona-Lasinio model. The $T$ dependence is determined from LQCD data on the renormalized chiral condensate around the pseudocritical temperature $T_{c}^{χ}$ of chiral crossover and the screening-mass difference between $π$ and $a_{0}$ mesons in $T > 1.1 T_{c}^{χ}$ where only the $U (1)_{A}$ -symmetry breaking survives. The model well reproduces LQCD data on screening masses $M_{ξ}^{scr} (T)$ for both scalar and pseudoscalar mesons, particularly in $T \geq T_{c}^{χ}$ . Using this effective model, we predict meson pole masses $M_{ξ}^{pole} (T)$ for scalar and pseudoscalar mesons. For $η^{'}$ meson, the prediction is consistent with the experimental value at finite $T$ measured in heavy-ion collisions. We point out that the relation $M_{ξ}^{scr} (T) - M_{ξ}^{pole} (T) \approx M_{ξ^{'}}^{scr} (T) - M_{ξ^{'}}^{pole} (T)$ is pretty good when $ξ$ and $ξ^{'}$ are scalar mesons, and show that the relation $M_{ξ}^{scr} (T) / M_{ξ^{'}}^{scr} (T) \approx M_{ξ}^{pole} (T) / M_{ξ^{'}}^{pole} (T)$ is well satisfied within 20% error when $ξ$ and $ξ^{'}$ are pseudoscalar mesons and also when $ξ$ and $ξ^{'}$ are scalar mesons.
↳ hep-phhep-exhep-latnucl-thPRD(2017)·28 citations
09
Strong Couplings of Three Mesons with Charm(ing) Involvement
Wolfgang Lucha🇦🇹 · Dmitri Melikhov🇦🇹 · Hagop Sazdjian🇫🇷 · Silvano Simula🇮🇹
We determine the strong couplings of three mesons that involve, at least, one $η_{c}$ or $J / ψ$ meson, within the framework of a constituent-quark model by means of relativistic dispersion formulations. For strong couplings of $J / ψ$ mesons to two charmed mesons, our approach leads to predictions roughly twice as large as those arising from QCD sum rules.
↳ hep-phnucl-thEPJ Web Conf.(2017)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Extraction of the proton charge radius from experiments

Anisotropic flow measurements in Pb--Pb collisions at 5.02 TeV with ALICE

Chiral medium produced by parallel electric and magnetic fields

Model prediction for temperature dependence of meson pole masses from lattice QCD results on meson screening masses

Strong Couplings of Three Mesons with Charm(ing) Involvement

Affiliations