scholarly journals Impact of off-shell dynamics on the transport properties and the dynamical evolution of charm quarks at RHIC and LHC temperatures

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Maria Lucia Sambataro ◽  
Salvatore Plumari ◽  
Vincenzo Greco
Keyword(s):  
Transport Properties ◽  
Transport Coefficients ◽  
Charm Quark ◽  
Dynamical Evolution ◽  
Collision Integral ◽  
Fixed Temperature ◽  
Charm Quarks ◽  
Shell Effects ◽  
Bulk Medium ◽  
Shell Dynamics

AbstractWe evaluate drag and diffusion transport coefficients comparing a quasi-particle approximation with on-shell constituents of the QGP medium and a dynamical quasi-particles model with off-shell bulk medium at finite temperature T. We study the effects of the width $$\gamma $$ γ of the particles of the bulk medium on the charm quark transport properties exploring the range where $$\gamma < M_{q,g}$$ γ < M q , g . We find that off-shell effects are in general quite moderate and can induce a reduction of the drag coefficient at low momenta that disappear already at moderate momenta, $$p \gtrsim $$ p ≳ 2–3 GeV. We also observe a moderate reduction of the breaking of the fluctuation–dissipation theorem (FDT) at finite momenta. Moreover, we have performed a first study of the dynamical evolution of HQ elastic energy loss in a bulk medium at fixed temperature extending the Boltzmann (BM) collision integral to include off-shell dynamics. A comparison among the Langevin dynamics, the BM collisional integral with on-shell and the BM extension to off-shell dynamics shows that the evolution of charm energy when off-shell effects are included remain quite similar to the case of the on-shell BM collision integral.

Effect of Electron-Phonon Coupling on Transport Properties of Monolayers of ZrS2, BiI3 and PbI2: A thermoelectric Perspective

2021 ◽  
Author(s):  
Gautam Sharma ◽  
Vineet Kumar Pandey ◽  
Shouvik Datta ◽  
Prasenjit Ghosh
Keyword(s):  
Relaxation Time ◽  
Band Structure ◽  
Transport Properties ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Waste Heat ◽  
Transport Coefficients ◽  
Electrical Energy ◽  
Phonon Coupling ◽  
Electron Phonon Coupling

Thermoelectric materials are used for conversion of waste heat to electrical energy. The transport coefficients that determine their thermoelectric properties depend on the band structure and the relaxation time of...

scholarly journals Annihilation diagram contribution to charmonium masses

2021 ◽  
Author(s):  
Renqiang 张仁强 Zhang ◽  
Ying Chen ◽  
Wei Sun ◽  
Zhaofeng Liu ◽  
Ming Gong ◽  
...  
Keyword(s):  
High Energy Physics ◽  
Charm Quark ◽  
High Energy ◽  
Mass Shift ◽  
Unitary Theory ◽  
Charm Quarks ◽  
Creative Commons ◽  
Anisotropic Lattices ◽  
Modern Physics ◽  
Academy Of Sciences

Abstract In this work, we generate gauge configurations with $N_f=2$ dynamical charm quarks on anisotropic lattices. The mass shift of $1S$ and $1P$ charmonia owing to the charm quark annihilation effect can be investigated directly in a manner of unitary theory. The distillation method is adopted to treat the charm quark annihilation diagrams at a very precise level. For $1S$ charmonia, the charm quark annihilation effect almost does not change the $J/\psi$ mass, but lifts the $\eta_c$ mass by approximately 3-4 MeV. For $1P$ charmonia, this effect results in positive mass shifts of approximately 1 MeV for $\chi_{c1}$ and $h_c$, but decreases the $\chi_{c2}$ mass by approximately 3 MeV. We have not obtain a reliable result for the mass shift of $\chi_{c0}$. In addition, it is observed that the spin averaged mass of the spin-triplet $1P$ charmonia is in a good agreement with the $h_c$, as expected by the non-relativistic quark model and measured by experiments. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Article funded by SCOAP3 and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Science and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.

CHARM QUARK THERMALIZATION IN QUARK-GLUON PLASMA

2007 ◽  
Vol 16 (07n08) ◽  
pp. 2048-2054 ◽  
Author(s):  
LI YAN ◽  
PENGFEI ZHUANG ◽  
NU XU
Keyword(s):  
Relaxation Time ◽  
Quark Gluon Plasma ◽  
Transport Model ◽  
Charm Quark ◽  
Gluon Plasma ◽  
Transverse Momentum Distribution ◽  
Hydrodynamic Description ◽  
Charm Quarks ◽  
Relaxation Time Approximation ◽  
Quark Transverse Momentum

The charm quark thermalization in quark-gluon plasma is described by a transport model in relaxation time approximation. Combining the transport equation for charm quarks with the hydrodynamic description for the medium, we calculated the charm quark transverse momentum distribution and discussed its dependence on the relaxation time.

scholarly journals Nature of the Interstitials in Titanium Dioxide and Their Impact on Transmission Coefficient:Ab InitioCalculations

2015 ◽  
Vol 2015 ◽  
pp. 1-9
Author(s):  
Lei Li ◽  
Changfu Xia ◽  
Wenshi Li ◽  
Aimin Ji ◽  
Canyan Zhu ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Ab Initio ◽  
Transport Properties ◽  
Transport Coefficients ◽  
Random Access ◽  
Random Access Memory ◽  
Resistive Random Access Memory ◽  
High Concentration ◽  
Access Memory ◽  
Excess Electrons

Theab initiocalculations about the properties of the interstitials doping in the rutile TiO2and their impact on the transport coefficients are reported. As the doping of the Zr or Ti interstitials in the TiO2, the lattice Ti4+ions acquire the excess electrons so reduced to the Ti3+or Ti2+ions. However, the Cu interstitials could not lose enough electrons to reduce the lattice Ti4+ions. Furthermore, the Ti or Cu interstitials in the ZrO2also are unable to promote the lattice Zr4+ions to form the lattice Zr3+or Zr2+ions. The high transport coefficients are observed in the defected TiO2with the Ti or Zr interstitials as the high concentration of the Ti3+or Ti2+ions. So, the Zr interstitials are the favorable choice for the extra-doping to improve the transport properties in the TiO2-based resistive random access memory.

scholarly journals Charm sea effects on charmonium decay constants and heavy meson masses

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
Salvatore Calì ◽  
Kevin Eckert ◽  
Jochen Heitger ◽  
Francesco Knechtli ◽  
Tomasz Korzec
Keyword(s):  
Lattice Qcd ◽  
Continuum Limit ◽  
Charm Quark ◽  
Heavy Meson ◽  
Charm Quarks ◽  
Decay Constants ◽  
Derivatives Of ◽  
Charm Mass ◽  
The Continuum

AbstractWe estimate the effects on the decay constants of charmonium and on heavy meson masses due to the charm quark in the sea. Our goal is to understand whether for these quantities $${N_\mathrm{f}}=2+1$$ N f = 2 + 1 lattice QCD simulations provide results that can be compared with experiments or whether $${N_\mathrm{f}}=2+1+1$$ N f = 2 + 1 + 1 QCD including the charm quark in the sea needs to be simulated. We consider two theories, $${N_\mathrm{f}}=0$$ N f = 0 QCD and QCD with $${N_\mathrm{f}}=2$$ N f = 2 charm quarks in the sea. The charm sea effects (due to two charm quarks) are estimated comparing the results obtained in these two theories, after matching them and taking the continuum limit. The absence of light quarks allows us to simulate the $${N_\mathrm{f}}=2$$ N f = 2 theory at lattice spacings down to 0.023 fm that are crucial for reliable continuum extrapolations. We find that sea charm quark effects are below 1% for the decay constants of charmonium. Our results show that decoupling of charm works well up to energies of about 500 MeV. We also compute the derivatives of the decay constants and meson masses with respect to the charm mass. For these quantities we again do not see a significant dynamical charm quark effect, albeit with a lower precision. For mesons made of a charm quark and a heavy antiquark, whose mass is twice that of the charm quark, sea effects are only about 1‰ in the ratio of vector to pseudoscalar masses.

scholarly journals The strangest proton?

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Ferran Faura ◽  
Shayan Iranipour ◽  
Emanuele R. Nocera ◽  
Juan Rojo ◽  
Maria Ubiali
Keyword(s):  
Cross Sections ◽  
Global Analysis ◽  
Charm Quark ◽  
Distribution Functions ◽  
Boson Production ◽  
Parton Distribution Functions ◽  
Charm Quarks ◽  
Charm Quark Mass ◽  
Input Dataset ◽  
Qcd Analysis

AbstractWe present an improved determination of the strange quark and antiquark parton distribution functions of the proton by means of a global QCD analysis that takes into account a comprehensive set of strangeness-sensitive measurements: charm-tagged cross sections for fixed-target neutrino–nucleus deep-inelastic scattering, and cross sections for inclusive gauge-boson production and W-boson production in association with light jets or charm quarks at hadron colliders. Our analysis is accurate to next-to-next-to-leading order in perturbative QCD where available, and specifically includes charm-quark mass corrections to neutrino–nucleus structure functions. We find that a good overall description of the input dataset can be achieved and that a strangeness moderately suppressed in comparison to the rest of the light sea quarks is strongly favored by the global analysis.

Measurement of D-meson production and flow in Pb–Pb collisions with ALICE at the LHC

2020 ◽  
pp. 2040004
Author(s):  
Fabio Catalano
Keyword(s):  
Energy Loss ◽  
D Meson ◽  
Charm Quark ◽  
Meson Production ◽  
Elliptic Flow ◽  
Gluon Plasma ◽  
Event Shape ◽  
Recombination Mechanism ◽  
Charm Quarks ◽  
Quark Energy Loss

Open-charmed mesons are unique tools to study the properties of the Quark–Gluon Plasma (QGP) formed in ultra-relativistic nucleus–nucleus collisions. The nuclear modification factor ([Formula: see text]) and elliptic flow ([Formula: see text]) of [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] mesons were measured by the ALICE Collaboration in Pb–Pb collisions at [Formula: see text]. The D-meson [Formula: see text] provides information on the charm-quark interactions with the medium and the charm-quark energy loss. The D-meson elliptic flow at low transverse momentum ([Formula: see text]) gives insight into the participation of charm quarks in the collective expansion of the system and their possible in-medium thermalization. At high [Formula: see text], the [Formula: see text] is sensitive to the path-length dependence of parton energy loss. The role of the recombination mechanism is investigated measuring the [Formula: see text]-differential yield ratios between D-meson species with and without strange-quark content. Finally, the coupling of charm quarks to light quarks of the underlying medium is examined applying the Event-Shape Engineering (ESE) technique to the nonstrange D-meson elliptic flow.

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