Nuclear Theory·nucl-th

Tuesday·February 21, 2017

19 papers—14 primary·5 cross-listed

15
NRQCD Confronts LHCb Data on Quarkonium Production within Jets
Reggie Bain🇺🇸 · Lin Dai🇺🇸 · Adam Leibovich🇺🇸 · Yiannis Makris🇺🇸 · Thomas Mehen🇺🇸
We analyze the recent LHCb measurement of the distribution of the fraction of the transverse momentum, $z (J / ψ)$ , carried by the $J / ψ$ within a jet. LHCb data is compared to analytic calculations using the fragmenting jet function (FJF) formalism for studying $J / ψ$ in jets. Logarithms in the FJFs are resummed using DGLAP evolution. We also convolve hard QCD partonic cross sections, showered with PYTHIA, with leading order Non Relativistic Quantum Chromodynamics (NRQCD) fragmentation functions and obtain consistent results. Both approaches use Madgraph to calculate the hard process that creates the jet initiating parton. These calculations give reasonable agreement with the $z (J / ψ)$ distribution that was shown to be poorly described by default PYTHIA simulations in the LHCb paper. We compare our predictions for the $J / ψ$ distribution using various extractions of nonperturbative NRQCD long-distance matrix elements (LDMEs) in the literature. NRQCD calculations agree with LHCb data better than default PYTHIA regardless of which fit to the LDMEs is used. LDMEs from fits that focus exclusively on high transverse momentum data from colliders are in good agreement with the LHCb measurement.
↳ hep-phnucl-thPRL(2017)·84 citations
16
Rotation-driven phase transitions in the cores of pulsars
R. D. Mellinger🇺🇸 · F. Weber🇺🇸 · W. Spinella🇺🇸 · G. A. Contrera🇦🇷 · M. Orsaria🇺🇸
In this paper, we discuss the impact of rotation on the particle composition of rotating neutron stars (pulsars). Particular emphasis is put on the formation of quark matter during stellar spin-down, driven by continuous gravitational compression. Our study is based on modern models for the nuclear equation of state whose parameters are tightly constrained by nuclear data, neutron star masses, and the latest estimates of neutron star radii.
↳ astro-ph.HEhep-phnucl-thInt.J.Mod.Phys.Conf.Ser.(2017)·0 citations
17
Energy loss of heavy quarks and $B$ and $D$ meson spectra in PbPb collisions at LHC energies
Kapil Saraswat🇮🇳 · Prashant Shukla🇮🇳 · Vineet Kumar🇮🇳 · Venktesh Singh🇮🇳
We study the production and evolution of charm and bottom quarks in hot partonic medium produced in heavy ion collisions. The heavy quarks loose energy in the medium which is reflected in the transverse momentum spectra of heavy mesons. The collisional energy loss of heavy quarks has been calculated using QCD calculations. The radiative energy loss is obtained using two models namely reaction operator formalism and generalized dead cone approach. The nuclear modification factors, $R_{AA}$ as a function of transverse momentum by including shadowing and energy loss are calculated for $D^{0}$ and $B^{+}$ mesons in PbPb collisions at $s_{N N}$ = 5.02 TeV and for $D^{0}$ mesons at $s_{N N}$ = 2.76 TeV and are compared with the recent measurements. The radiative energy loss from generalized dead cone approach alone is sufficient to produce measured $D^{0}$ meson $R_{AA}$ at both the LHC energies. The radiative energy loss from reaction operator formalism plus collisional energy loss gives good description of $D^{0}$ meson $R_{AA}$ . For the case of $B^{+}$ meson, the radiative energy loss from generalized dead cone approach plus collisional energy loss gives good description of the CMS data. The radiative process is dominant for charm quarks while for the bottom, both the radiative process and the elastic collisions are important.
↳ hep-phnucl-thNPA(2017)·16 citations
18
Photoproduction of $η$ and $η^{'}$ Mesons on Proton
V.L. Kashevarov🇩🇪 · L. Tiator🇩🇪 · M. Ostrick (for the A2 Collaboration at MAMI)🇩🇪
New high-precision total and differential cross sections for $η$ and $η^{'}$ photoproduction on the proton obtained by the A2 Collaboration at the Mainz Microtron are presented. The data for $η$ photoproduction demonstrate a cusp at the energy W $\sim$ 1.9~GeV. Furthermore, we present a new version of the $η$ MAID model for $η$ and $η^{'}$ photoproduction. The model includes 23 nucleon resonances parametrized with Breit-Wigner shapes. The background is described by vector and axial-vector meson exchanges in the $t$ channel using the Regge phenomenology. Parameters of the resonances were obtained from a fit to preliminary data of the A2 Collaboration at MAMI and available data from other collaborations. The cusp is explained as a threshold effect due to the opening $η^{'} p$ decay channel of the $N (1895) 1/ 2^{-}$ resonance.
↳ nucl-exhep-phnucl-thJPS Conf.Proc.(2017)·10 citations
19
Quark-hadron Phase Transition in Proto-Neutron Stars Cores based on a Non-local NJL Model
German Malfatti🇦🇷 · G. A. Contrera🇦🇷 · M. Orsaria🇦🇷 · F. Weber🇺🇸
We study the QCD phase diagram using a non-local SU(3) NJL model with vector interactions among quarks. We analyze several thermodynamic quantities such as entropy and specific heat, and study the influence of vector interactions on the thermodynamic properties of quark matter. Upon imposing electric charge neutrality and baryon number conservation on the field equations, we compute models for the equation of state of the inner cores of proto-neutron stars providing a non-local treatment of quark matter for astrophysics.
↳ astro-ph.HEnucl-thInt.J.Mod.Phys.Conf.Ser.(2017)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE

NRQCD Confronts LHCb Data on Quarkonium Production within Jets

Rotation-driven phase transitions in the cores of pulsars

Energy loss of heavy quarks and B and D meson spectra in PbPb collisions at LHC energies

Photoproduction of η and η′ Mesons on Proton

Quark-hadron Phase Transition in Proto-Neutron Stars Cores based on a Non-local NJL Model

Affiliations

Energy loss of heavy quarks and $B$ and $D$ meson spectra in PbPb collisions at LHC energies

Photoproduction of $η$ and $η^{'}$ Mesons on Proton