Nuclear Theory·nucl-th

Wednesday·July 18, 2018

24 papers—12 primary·12 cross-listed

13
Lattice QCD Method To Study Hadron Mass Is Not Correct
Gouranga C Nayak🇺🇸
Since the numerical path integration in the lattice QCD involves quark and gluon fields (not hadron fields) the lattice QCD cannot calculate any hadronic observable. Because of this reason the hadronic properties are extracted in the lattice QCD method by inserting complete set of hadron states $\sum_{n} ∣ n >< n ∣ = 1$ in between the partonic operators by assuming $H_{QCD} ∣ n >= E_{n} ∣ n >$ where $E_{n}$ is the energy of the hadron. However, in this paper we find $H_{QCD} ∣ n > \neq = E_{n} ∣ n >$ because the QCD hamiltonian $H_{QC D}$ is unphysical but the $E_{n}$ and $∣ n >$ of the hadron are physical. We show that this is consistent with $E_{QCD} (t) =< n ∣ H_{QC D} ∣ n > \neq = E_{n}$ due to non-zero energy flux $E_{flux} (t)$ in QCD because of confinement involving non-perturbative QCD. Hence we find that the lattice QCD method to study hadron mass is not correct.
↳ hep-lathep-phnucl-th2 citations
14
Multiparticle correlations and collectivity in small systems from the initial state
Kevin Dusling🇺🇸 · Mark Mace🇺🇸 · Vladimir V. Skokov🇺🇸 · Prithwish Tribedy🇺🇸 · Raju Venugopalan🇺🇸
We report on recent progress in understanding multiparticle correlations in small systems from the initial state. First, we consider a proof-of-principle parton model, which we use to demonstrate that many of the multiparticle correlations observed in light-heavy ion collisions, often ascribed to hydrodynamic collectivity, can be qualitatively reproduced in an initial state model. Then, we study the two-particle harmonics $v_{2}$ and $v_{3}$ for p/d/ $^{3}$ He+Au collisions at RHIC using the dilute-dense Color Glass Condensate Effective Field Theory framework. We show that this provides a viable alternative explanation to hydrodynamics, and elaborate on how such modeling can be improved.
↳ hep-phnucl-exnucl-thNPA(2019)·0 citations
15
Charge and spin asymmetries in elastic lepton-nucleon scattering
Oleksandr Koshchii🇺🇸 · Andrei Afanasev🇺🇸
Elastic lepton scattering off of a nucleon has proved to be an efficient tool to study the structure of the hadron. Modern cross section and asymmetry measurements at Jefferson Lab require effects beyond the leading order Born approximation to be taken into account. Availability of unpolarized beams of both electrons and positrons in respective experiments would enable to reduce systematic uncertainties due to higher-order charge-odd contributions. In addition, information on an unpolarized electron-to-positron cross section ratio could serve as a test for theoretical models that provide predictions for charge-dependent radiative corrections to elastic lepton-nucleon scattering. Availability of polarized beams of leptons would allow for even more comprehensive study of higher-order effects as some of them are dominant in polarized lepton-nucleon scattering asymmetries. We present a brief overview of effects due to the lepton's charge and target's polarization on elastic lepton-nucleon scattering measurements.
↳ hep-phnucl-thAIP Conf.Proc.(2018)·2 citations
16
Universal quark to gluon ratio in medium-induced parton cascade
Yacine Mehtar-Tani🇺🇸 · Soeren Schlichting🇺🇸
We investigate the radiative break-up of a highly energetic quark or gluon in a high-temperature QCD plasma. Within an inertial range of momenta $T ≪ ω ≪ E$ , where $E$ denotes the energy of the original hard parton (jet) and $T$ the temperature of of the medium, we find that, as a result of the turbulent nature of the underlying parton cascade, the quark to gluon ratio of the soft fragments tends to a universal constant value that is independent of the initial conditions. We discuss implications of this result to jet quenching physics and the problem of thermalization of the quark-gluon plasma in heavy ion collisions.
↳ hep-phnucl-thJHEP(2018)·46 citations
17
Global Dyson-Schwinger-Bethe-Salpeter Approach to Mesons with Open Flavour
Thomas Hilger🇦🇹 · María Gómez-Rocha🇮🇹 · Andreas Krassnigg🇦🇹 · Wolfgang Lucha🇦🇹
Exploiting an interplay of the Bethe-Salpeter equation enabling us to regard mesons as bound states of quark and antiquark and the Dyson-Schwinger equation controlling the dressed quark propagator, we amend existing studies of quarkonia by a comprehensive description of open-flavour mesons composed of all conceivable combinations of quark flavour. Employing throughout a fixed set of model parameters, we predict some basic characteristics of these mesons, i.e., their masses, leptonic decay constants and corresponding in-hadron condensates entering in a generalized formulation of the Gell-Mann-Oakes-Renner relation.
↳ hep-phhep-exnucl-thEPJ Web Conf.(2018)·2 citations
18
Signature of gluon saturation in forward di-hadron correlations at the Large Hadron Collider
Giuliano Giacalone🇫🇷 · Cyrille Marquet🇫🇷
We argue that gluon saturation effects may be visible in Large Hadron Collider (LHC) data. We look at the centrality dependence of the away-side peak of two-particle correlations measured in p-Pb collisions, using both ALICE data at midrapidity, and LHCb data at forward rapidity. Once the collective flow-like signal measured at the near-side peak is removed from the correlation function, the centrality dependence of the away-side peak turns out to be much stronger in the forward region than at midrapidity. We argue that this is a very specific prediction of the saturation framework, and we compare LHCb data to a state-of-the-art calculation within the Color Glass Condensate theory.
↳ hep-phhep-exnucl-exnucl-thNPA(2019)·8 citations
19
Lattice-based QCD equation of state at finite baryon density: Cluster Expansion Model
V. Vovchenko🇩🇪 · J. Steinheimer🇩🇪 · O. Philipsen🇩🇪 · A. Pasztor🇩🇪 · Z. Fodor🇩🇪 · S.D. Katz🇭🇺 · H. Stoecker🇩🇪
The QCD equation of state at finite baryon density is studied in the framework of a Cluster Expansion Model (CEM), which is based on the fugacity expansion of the net baryon density. The CEM uses the two leading Fourier coefficients, obtained from lattice simulations at imaginary $μ_{B}$ , as the only model input and permits a closed analytic form. Excellent description of the available lattice data at both $μ_{B} = 0$ and at imaginary $μ_{B}$ is obtained. We also demonstrate how the Fourier coefficients can be reconstructed from baryon number susceptibilities.
↳ hep-lathep-phnucl-thNPA(2019)·21 citations
20
Effect of the magnetized medium on the decay of neutral scalar bosons
Aritra Bandyopadhyay🇧🇷 · Ricardo L. S. Farias🇧🇷 · Rudnei O. Ramos🇧🇷
The decay of a heavy neutral scalar particle into fermions and into charged scalars are analyzed when in the presence of an external magnetic field and finite temperature. Working in the one-loop approximation for the study of these decay channels, it is shown that the magnetic field leads in general to a suppression of the decay width whenever the kinematic constrain depends explicitly on the magnetic field. Our results are also compared with common approximations found in the literature, e.g., when the magnitude of the external magnetic field is smaller than the decaying product particle masses, i.e., in the weak field approximation, and in the opposite case, i.e., in the strong field approximation. Possible applications of our results are discussed.
↳ hep-phhep-thnucl-thPRD(2018)·9 citations
21
Charged Kaon multiplicities of Semi-inclusive DIS off the deuteron target
Chung-Wen Kao🇹🇼 · Dong-Jing Yang🇹🇼 · Wen-Chen Chang🇹🇼
We investigate the results of the charged kaon multiplicities off the deuteron target from HERMES and COMPASS experiments. The discrepancy of the two data sets cannot be explained by different $Q^{2}$ values. Furthermore we examine the empirical parametrization of the fragmentation functions, DSS2017, and find that the agreement between the theoretical predictions and the HERMES data is less satisfactory as claimed.
↳ hep-phhep-exnucl-exnucl-th2 citations
22
Unpolarized isovector quark distribution function from Lattice QCD: A systematic analysis of renormalization and matching
Yu-Sheng Liu🇨🇳 · Jiunn-Wei Chen🇹🇼 · Yi-Kai Huo🇨🇳 · Luchang Jin🇺🇸 · Maximilian Schlemmer🇩🇪 · Andreas Schäfer🇩🇪 · Peng Sun🇨🇳 · Wei Wang🇨🇳 · Yi-Bo Yang🇺🇸 · Jian-Hui Zhang🇩🇪 · Qi-An Zhang🇨🇳 · Kuan Zhang🇨🇳 · Yong Zhao🇺🇸
We present a detailed Lattice QCD study of the unpolarized isovector quark Parton Distribution Function (PDF) using large-momentum effective theory framework. We choose a quasi-PDF defined by a spatial correlator which is free from mixing with other operators of the same dimension. In the lattice simulation, we use a Gaussian-momentum-smeared source at $M_{π} = 356$ MeV and $P_{z} \in {1.8, 2.3}$ GeV. To control the systematics associated with the excited states, we explore {five different source-sink separations}. The nonperturbative renormalization is conducted in a regularization-independent momentum subtraction scheme, and the matching between the renormalized quasi-PDF and $MS ˉ$ PDF is calculated based on perturbative QCD up to one-loop order. Systematic errors due to renormalization and perturbative matching are also analyzed in detail. Our results for lightcone PDF are in reasonable agreement with the latest phenomenological analysis.
↳ hep-lathep-exhep-phnucl-ex+1PRD(2020)·119 citations
23
In-medium enhancement of the modified Urca neutrino reaction rates
P.S. Shternin🇷🇺 · M. Baldo🇮🇹 · P. Haensel🇵🇱
We calculate modified Urca neutrino emission rates in the dense nuclear matter in neutron star cores. We find that these rates are strongly enhanced in the beta-stable matter in regions of the core close to the direct Urca process threshold. This enhancement can be tracked to the use of the in-medium nucleon spectrum in the virtual nucleon propagator. We describe the in-medium nucleon scattering in the non-relativistic Bruckner-Hartree-Fock framework taking into account two-body as well as the effective three-body forces, although the proposed enhancement does not rely on a particular way of the nucleon interaction treatment. Finally we suggest a simple approximate expression for the emissivity of the n-branch of the modified Urca process that can be used in the neutron stars cooling simulations with any nucleon equation of state of dense matter.
↳ astro-ph.HEnucl-thPLB(2018)·40 citations
24
Constraining neutron-star equation of state using heavy-ion collisions
C.Y. Tsang🇺🇸 · M.B. Tsang🇺🇸 · P. Danielewicz🇺🇸 · W.G. Lynch🇺🇸 · F.J. Fattoyev🇺🇸
The LIGO-Virgo collaboration ground-breaking detection of the binary neutron-star merger event, GW170817, has intensified efforts towards the understanding of the equation of state (EoS) of nuclear matter. In this letter, we compare directly the density-pressure constraint on the EoS obtained from a recent analysis of the neutron-star merger event to density-pressure constraints obtained from nuclear physics experiments. To relate constraints from nuclear physics to the radii and the tidal deformabilities of neutron stars, we use a large collection of Skyrme density functionals that describe properties of nuclei to calculate properties of 1.4 solar maass neutron stars. We find that restricting this set of Skyrme equations of state to density functionals that describe nuclear masses, isobaric analog states, and low energy nuclear reactions does not sufficiently restrict the predicted neutron-star radii and the tidal deformabilities. Including pressure constraints on the EoS around twice saturation density, obtained from high energy nucleus-nucleus collisions, does constrain predicted radii and tidal deformabilities to be consistent with the results obtained from the analysis of GW170817. We discuss how new measurements of nucleus-nucleus collisions can improve these constraints on the EoS to be more restrictive than the current constraints from the GW170817 merger event.
↳ nucl-exnucl-th38 citations

Affiliations

first authorsco-authorsvia INSPIRE