Nuclear Theory·nucl-th

Thursday·September 19, 2019

8 papers—4 primary·4 cross-listed

01
The Shape of the Correlation Function
Jakub Cimerman🇨🇿 · Christopher Plumberg🇸🇪 · Boris Tomášik🇸🇰
The two-particle correlation function employed in Hanbury-Brown Twiss interferometry and femtoscopy is traditionally parameterized by a Gaussian form. Other forms, however, have also been used, including the somewhat more general Lévy form. Here we consider a variety of effects present in realistic femtoscopic studies which may modify the shape of the correlation function and thereby influence the physical interpretation of a given parameterization.
nucl-thhep-phnucl-exPhys.Part.Nucl.(2020)·8 citations
02
Recent highlights with baryons from lattice QCD
Colin Morningstar🇺🇸
Highlights from recent computations in lattice QCD involving baryons are presented. Calculations of the proton mass and spin decompositions are discussed, a percent level determination of the nucleon axial coupling is described, and determinations of the proton and neutron electromagnetic form factors and light-cone parton distribution functions are outlined. Recent results applying the so-called Lüscher method to meson-baryon systems are presented. Key points emphasized are that much better precision with disconnected diagrams is being achieved, incorporating multi-hadron operators is now feasible, and more and more studies are being done with physical quark masses.
nucl-thhep-latEPJ Web Conf.(2020)·2 citations
03
Interplay between shape-phase transitions and shape coexistence in the Zr isotopes
N. Gavrielov · A. Leviatan · F. Iachello
We investigate the evolution of structure in the zirconium isotopes where one of the most complex situations encountered in nuclear physics occurs. We demonstrate the role of two concurrent types of quantum phase transitions, sharing a common critical point. The first type, involves an abrupt crossing of coexisting normal and intruder configurations. The second type, involves a gradual shape-phase transition within the intruder configuration, changing from weakly-deformed to prolate-deformed and finally to gamma-unstable. Evidence for this scenario is provided by a detailed comparison with experimental data, using a definite algebraic framework.
nucl-thPhys.Scripta(2020)·22 citations
04
Eigenvector Continuation as an Efficient and Accurate Emulator for Uncertainty Quantification
S. König🇩🇪 · A. Ekström🇸🇪 · K. Hebeler🇩🇪 · D. Lee🇺🇸 · A. Schwenk🇩🇪
First principles calculations of atomic nuclei based on microscopic nuclear forces derived from chiral effective field theory (EFT) have blossomed in the past years. A key element of such ab initio studies is the understanding and quantification of systematic and statistical errors arising from the omission of higher-order terms in the chiral expansion as well as the model calibration. While there has been significant progress in analyzing theoretical uncertainties for nucleon-nucleon scattering observables, the generalization to multi-nucleon systems has not been feasible yet due to the high computational cost of evaluating observables for a large set of low-energy couplings. In this Letter we show that a new method called eigenvector continuation (EC) can be used for constructing an efficient and accurate emulator for nuclear many-body observables, thereby enabling uncertainty quantification in multi-nucleon systems. We demonstrate the power of EC emulation with a proof-of-principle calculation that lays out all correlations between bulk ground-state observables in the few-nucleon sector. On the basis of ab initio calculations for the ground-state energy and radius in 4He, we demonstrate that EC is more accurate and efficient compared to established methods like Gaussian processes.
nucl-thPLB(2020)·140 citations
05
Second look to the Polyakov Loop Nambu-Jona-Lasinio model at finite baryonic density
O. Ivanytskyi🇪🇸 · M. Ángeles Pérez-García🇪🇸 · V. Sagun🇵🇹 · C. Albertus🇪🇸
We revisit the Polyakov Loop coupled Nambu-Jona-Lasinio model that maintains the Polyakov loop dynamics in the limit of zero temperature. This is of interest for astrophysical applications in the interior of neutron stars. For this purpose we re-examine the form of the potential for the deconfinement order parameter at finite baryonic densities. Since the modification of this potential at any temperature is formally equivalent to assigning a baryonic charge to gluons, we develop a more general formulation of the present model that cures this spurious effect and is normalized to match the asymptotic behaviour of the QCD equation of state given by $O (α_{s}^{2})$ and partial $O (α_{s}^{3} ln^{2} α_{s})$ perturbative results.
↳ hep-phastro-ph.HEnucl-thPRD(2019)·19 citations
06
Attractive inter-particle force in Van der Waals model of hadron gas in the grand canonical ensemble
Yaroslav Krivenko-Emetov🇺🇦
We generalize derivation of partition functions of the grand canonical ensemble for the multicomponent van der Waals gas of interacting particles by hardcore potentials to the case of the attractive large-distance mean field. The formulas obtained by the saddle point method for the thermodynamic potentials with the transparent non-relativistic limit to the case of conserving large number of particles for different gas components like neutrons and protons of nuclear matter can be used for analysis of experimental data for the particle number ratios in nucleus-nucleus collisions at high excitation energies.
↳ hep-phnucl-th4 citations
07
Pion Valence Structure from Ioffe Time Pseudo-Distributions
Bálint Joó🇺🇸 · Joseph Karpie🇺🇸 · Kostas Orginos🇺🇸 · Anatoly V. Radyushkin🇺🇸 · David G. Richards🇺🇸 · Raza Sabbir Sufian🇺🇸 · Savvas Zafeiropoulos🇩🇪
We present a calculation of the pion valence quark distribution extracted using the formalism of reduced Ioffe time pseudo-distributions or more commonly known as pseudo-PDFs. Our calculation is carried out on two different 2+1 flavor QCD ensembles using the isotropic-clover fermion action, with lattice dimensions $2 4^{3} \times 64$ and $3 2^{3} \times 96$ at the lattice spacing of $a = 0.127$ fm, and with the quark mass equivalent to a pion mass of $m_{π} ≃ 415$ MeV. We incorporate several combinations of smeared-point and smeared-smeared pion source-sink interpolation fields in obtaining the lattice QCD matrix elements using the summation method. After one-loop perturbative matching and combining the pseudo-distributions from these two ensembles, we extract the pion valence quark distribution using a phenomenological functional form motivated by the global fits of parton distribution functions. We also calculate the lowest four moments of the pion quark distribution through the "OPE without OPE". We present a qualitative comparison between our lattice QCD extraction of the pion valence quark distribution with that obtained from global fits and previous lattice QCD calculations.
↳ hep-lathep-phnucl-exnucl-thPRD(2019)·159 citations
08
Probing parton saturation with forward $Z^{0}$ -boson production at small transverse momentum in p+p and p+A collisions
Cyrille Marquet🇫🇷 · Shu-Yi Wei🇫🇷 · Bo-Wen Xiao🇨🇳
We calculate and compare the differential cross sections for forward $Z^{0}$ -boson production at small transverse momentum, in proton-proton and proton-nucleus collisions, using both the collinear and dilute-dense factorization frameworks. In both cases, we implement a Sudakov resummation of the large logarithms generated by soft-gluon emissions, which is essential in order to describe the transverse momentum distribution of forward $Z^{0}$ bosons measured at the Tevatron and the LHC. We further compute the nuclear modification factor in the dilute-dense framework, hoping to single out signals of saturation effects at small values of $x$ . Our predictions are compared with those obtained in the collinear factorization framework, using two different nuclear parton distribution functions.
↳ hep-phhep-exnucl-thPLB(2020)·21 citations

Affiliations

first authorsco-authorsvia INSPIRE