Nuclear Theory·nucl-th

Friday·February 15, 2019

11 papers—6 primary·5 cross-listed

01
[Submitted on 13 Feb 2019]
Equation of state at finite densities for QCD matter in nuclear collisions
Akihiko Monnai🇯🇵 · Björn Schenke🇺🇸 · Chun Shen🇺🇸
We construct the QCD equation of state at finite chemical potentials including net baryon, electric charge, and strangeness, based on the conserved charge susceptibilities determined from lattice QCD simulations and the equation of state of the hadron resonance gas model. For the application to relativistic heavy ion collisions we consider the situation of strangeness neutrality and matter with a fixed electric charge-to-baryon ratio, resembling that of heavy nuclei. The importance of finite electric charge and strangeness chemical potentials for particle production in heavy ion collisions is demonstrated using hydrodynamic simulations.
Comments:
14 pages, 9 figures; revised version to appear in Physical Review C
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1902.05095 [pdf]
PRC(2019)·180 citations
02
[Submitted on 14 Feb 2019]
Coherent dibaryons
Boris Kostenko🇷🇺
There are encouraging evidences for registration of excitations of quark oscillator levels in compressed 2-nucleon systems, which were hidden in two independently published experimental works for many years. Data obtained by EVA collaboration can be considered as the third possible confirmation of this conjecture. Moreover, they drop hints about existence of coherent dibaryons which may be interpreted as usual or generalized coherent states of the oscillator. These data may also be an explicit example of a physical process described by Landau and Peierls in their reasoning concerning the energy-time uncertainty relation. Two models of the coherent dibaryon creation are formulated. Phase transitions of baryon matter in few-nucleon systems are discussed.
Comments:
Reported at Baldin ISHEPP XXIV, September 19, 2018
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1902.05252 [pdf]
1 citation
03
[Submitted on 14 Feb 2019]
Photoproduction $γ p \to K^{*+} Λ$ in a Reggeized model
Ai-Chao Wang🇨🇳 · Fei Huang🇨🇳 · Wen-Ling Wang🇨🇳 · Guang-Xiong Peng🇨🇳
The high-precision differential cross-section data for the reaction $γ p \to K^{*+} Λ$ are reanalyzed within a Regge-inspired effective Lagrangian approach. The model adopts Regge phenomenology to constrain the $t$ -channel contributions from the $κ$ , $K$ , and $K^{*}$ exchanges. A minimal number of resonances in the $s$ channel are introduced in constructing the reaction amplitudes in order to describe the data. It is shown that the differential cross-section data for $γ p \to K^{*+} Λ$ can be satisfactorily described by introducing the only $N (2060) 5/2^{-}$ resonance in the $s$ channel, which is quite different from our earlier work performed in an effective Lagrangian approach [A. C. Wang {\it et al.}, Phys. Rev. C 96, 035206 (2017)], where the amplitudes are computed by evaluating Feynman diagrams and it is found that introducing at least one additional resonance apart from the $N (2060) 5/2^{-}$ is indispensable for reproducing the data. The roles of individual contributions from meson and baryon exchanges on the angular distributions are found to be highly model dependent. The extracted mass of $N (2060) 5/2^{-}$ turns out to be well determined, independent of how the $t$ -channel amplitudes are constructed, whereas the width does not.
Comments:
10 pages, 5 figures, version published in PRC
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1902.05267 [pdf]
PRC(2020)·11 citations
04
[Submitted on 14 Feb 2019]
Triplet structure of nuclear scissors mode
E. B. Balbutsev🇷🇺 · I. V. Molodtsova🇷🇺 · A. V. Sushkov · N. Yu. Shirikova · P. Schuck🇫🇷
The fine structure of the scissors mode is investigated within the Time Dependent Hartree-Fock-Bogoliubov (TDHFB) approach. The solution of TDHFB equations by the Wigner Function Moments (WFM) method predicts a splitting of the scissors mode into three intermingled branches. Together with the conventional scissors mode two new modes arise due to spin degrees of freedom. They generate significant $M 1$ strength below the conventional energy range. The results of calculations of scissors resonances in Rare Earths and Actinides by WFM and QPNM methods are compared with experimental data. A remarkable coherence of both methods together with experimental data is observed.
Comments:
24 pages, 11 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1902.05275 [pdf]
Phys.Atom.Nucl.(2020)·4 citations
05
[Submitted on 14 Feb 2019]
Approximate self-energy for Fermi systems with large s-wave scattering length: a step towards density functional theory
Antoine Boulet🇫🇷 · Denis Lacroix🇫🇷
In the present work, we start from a minimal Hamiltonian for Fermi systems where the s-wave scattering is the only low energy constant at play. Many-Body Perturbative approach that is usually valid at rather low density is first discussed. We then use the resummation technique with the ladder approximation to obtain compact expressions for both the energy and/or the on-shell self-energy in infinite spin-degenerated systems. Diagrammatic resummation technique has the advantage in general to be predictive in a region of density larger compared to many-body perturbation theory. It also leads to non-diverging limit as $∣ a_{s} ∣ \to + \infty$ . Still, the obtained expressions are rather complex functional of the Fermi momentum $k_{F}$ . We introduce the full phase-space average or the partial phase-space methods respectively applied to the energy or to the self-energy to simplify their dependences in terms of $(a_{s} k_{F})$ while keeping the correct limit at low density and the non-diverging property at large $∣ a_{s} k_{F} ∣$ . Quasi-particle properties of Fermi system in various regime of density and scattering length are then illustrated. Our conclusion is that such simplified expressions where the direct link is made with the low energy constant without fine-tuning can provide a clear guidance to obtain density functional theory beyond the perturbative regime. However, quasi-particle properties close or near unitary cannot be reproduced unless this limit is explicitly used as a constraint. We finally discuss how such approximate treatment of quasi-particle can guide the development of density functional theory for strongly interacting Fermi systems.
Subjects:
Nuclear Theory (nucl-th); Quantum Gases (cond-mat.quant-gas)
arXiv:
1902.05477 [pdf]
J.Phys.G(2019)·10 citations
06
[Submitted on 14 Feb 2019]
Bayesian modeling of the nuclear equation of state for neutron star tidal deformabilities and GW170817
Y. Lim🇺🇸 · J. W. Holt🇺🇸
We present predictions for neutron star tidal deformabilities obtained from a Bayesian analysis of the nuclear equation of state, assuming a minimal model at high-density that neglects the possibility of phase transitions. The Bayesian posterior probability distribution is constructed from priors obtained from microscopic many-body theory based on realistic two- and three-body nuclear forces, while the likelihood functions incorporate empirical information about the equation of state from nuclear experiments. The neutron star crust equation of state is constructed from the liquid drop model, and the core-crust transition density is found by comparing the energy per baryon in inhomogeneous matter and uniform nuclear matter. From the cold $β$ -equilibrated neutron star equation of state, we then compute neutron star tidal deformabilities as well as the mass-radius relationship. Finally, we investigate correlations between the neutron star tidal deformability and properties of finite nuclei.
Comments:
15 pages, 17 figures. Invited contribution to the EPJA Topical Issue "First joint gravitational wave and electromagnetic observations: Implications for nuclear and particle physics"
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
1902.05502 [pdf]
EPJA(2019)·111 citations
07
[Submitted on 13 Feb 2019] (cross-list from hep-ph)
Diffractive Dijet Production and Wigner Distributions from the Color Glass Condensate
Heikki Mäntysaari🇫🇮 · Niklas Mueller🇺🇸 · Björn Schenke🇺🇸
Experimental processes that are sensitive to parton Wigner distributions provide a powerful tool to advance our understanding of proton structure. In this work, we compute gluon Wigner and Husimi distributions of protons within the Color Glass Condensate framework, which includes a spatially dependent McLerran-Venugopalan initial configuration and the explicit numerical solution of the JIMWLK equations. We determine the leading anisotropy of the Wigner and Husimi distributions as a function of the angle between impact parameter and transverse momentum. We study experimental signatures of these angular correlations at a proposed Electron Ion Collider by computing coherent diffractive dijet production cross sections in e+p collisions within the same framework. Specifically, we predict the elliptic modulation of the cross section as a function of the relative angle between nucleon recoil and dijet transverse momentum for a wide kinematical range. We further predict its dependence on collision energy, which is dominated by the growth of the proton with decreasing $x$ .
Comments:
prefactors for longitudinal and transverse cross sections corrected, figures updated, typos corrected, 20 pages, 22 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1902.05087 [pdf]
PRD(2019)·90 citations
08
[Submitted on 13 Feb 2019] (cross-list from hep-ph)
Constraints on nuclear parton distributions from dijet photoproduction at the LHC
V. Guzey (Jyvaskyla U., Helsinki U., St. Petersburg, INP)🇫🇮 · M. Klasen (Munster U., ITP)🇩🇪
Using QCD calculations of the cross section of inclusive dijet photoproduction in Pb-Pb ultraperipheral collisions in the LHC kinematics as pseudo-data, we study the effect of including these data using the Bayesian reweighting technique on nCTEQ15, nCTEQ15np, and EPPS16 nuclear parton distribution functions (nPDFs). We find that, depending on the assumed error of the pseudo-data, it leads to a significant reduction of the nPDF uncertainties at small values of the momentum fraction $x_{A}$ . Taking the error to be 5\%, the uncertainty of nCTEQ15 and nCTEQ15np nPDFs reduces approximately by a factor of two at $x_{A} = 1 0^{- 3}$ . At the same time, the reweighting effect on EPPS16 nPDFs is much smaller due to the higher value of the tolerance and a more flexible parametrization form.
Comments:
16 pages, 11 figures. Final published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1902.05126 [pdf]
EPJC(2019)·29 citations
09
[Submitted on 14 Feb 2019] (cross-list from nucl-ex)
Experimental nuclear astrophysics in Italy
C. Broggini🇮🇹 · O. Straniero🇮🇹 · M.G.F. Taiuti🇮🇹 · G. de Angelis🇮🇹 · G. Benzoni🇮🇹 · G.E. Bruno🇮🇹 · S. Bufalino🇮🇹 · G. Cardella🇮🇹 · N. Colonna🇮🇹 · M. Contalbrigo🇮🇹 · G. Cosentino🇮🇹 · S. Cristallo🇮🇹 and 27 other authors
Nuclear astrophysics, the union of nuclear physics and astronomy, went through an impressive expansion during the last twenty years. This could be achieved thanks to milestone improvements in astronomical observations, cross section measurements, powerful computer simulations and much refined stellar models. Italian groups are giving quite important contributions to every domain of nuclear astrophysics, sometimes being the leaders of worldwide unique experiments. In this paper we will discuss the astrophysical scenarios where nuclear astrophysics plays a key role and we will provide detailed descriptions of the present and future of the experiments on nuclear astrophysics which belong to the scientific programme of INFN (the National Institute for Nuclear Physics in Italy).
Comments:
Added paragraphs 5.6 and 7.2. Paragraph 7.3 (former 7.2) revised. Accepted for publication in La Rivista del Nuovo Cimento
Subjects:
Nuclear Experiment (nucl-ex); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
1902.05262 [pdf]
Riv.Nuovo Cim.(2019)·18 citations
10
[Submitted on 14 Feb 2019] (cross-list from hep-ph)
First order dissipative hydrodynamics and viscous corrections to the entropy four-current from an effective covariant kinetic theory
Samapan Bhadury🇮🇳 · Manu Kurian🇮🇳 · Vinod Chandra🇮🇳 · Amaresh Jaiswal🇮🇳
The first order hydrodynamic evolution equations for the shear stress tensor, the bulk viscous pressure and the charge current have been studied for a system of quarks and gluons, with a non-vanishing quark chemical potential and finite quark mass. The first order transport coefficients have been obtained by solving an effective Boltzmann equation for the grand-canonical ensemble of quasiquarks and quasigluons. We adopted temperature dependent effective fugacity for the quasiparticles to encode the hot QCD medium effects. The non-trivial energy dispersion of the quasiparticles induces mean field contributions to the transport coefficients whose origin could be directly related to the realization of conservation laws from the effective kinetic theory. Both the QCD equation of state and chemical potential are seen to have a significant impact on the quark-gluon plasma evolution. The shear and bulk viscous corrections to the entropy-four current have been investigated in the framework of the effective kinetic theory. The effect of viscous corrections to the entropy density have been quantified in the case of one dimensional boost-invariant expansion of the system. Further, the first order viscous corrections to the time evolution of temperature along with the description of pressure anisotropy and Reynolds number of the system have been explored for the longitudinal boost-invariant expansion.volution of temperature along with the description of pressure anisotropy of the system have also been explored.
Comments:
15 pages, 11 figures, version accepted for publication in Journal of Physics G
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1902.05285 [pdf]
J.Phys.G(2020)·24 citations
11
[Submitted on 14 Feb 2019] (cross-list from hep-ph)
Baryon-number violation by two units and the deuteron lifetime
F. Oosterhof🇳🇱 · B. Long🇨🇳 · J. de Vries🇺🇸 · R. G. E. Timmermans🇳🇱 · U. van Kolck🇫🇷
We calculate the lifetime of the deuteron with dimension-nine quark operators that violate baryon number by two units. We construct an effective field theory for $∣Δ B ∣ = 2$ interactions that give rise to neutron-antineutron ( $n$ - $n ˉ$ ) oscillations and dinucleon decay within a consistent power counting. We calculate the ratio of the deuteron lifetime to the square of the $n$ - $n ˉ$ oscillation time up to next-to-leading order. Our result, which is analytical and has a quantified uncertainty, is smaller by a factor $≃ 2.5$ than earlier estimates based on nuclear models, which impacts the indirect bound on he $n$ - $n ˉ$ oscillation time and future experiments. We discuss how combined measurements of $n$ - $n ˉ$ oscillations and deuteron decay can help to identify the sources of baryon-number violation.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1902.05342 [pdf]
PRL(2019)·42 citations

Affiliations

first authorsco-authorsvia INSPIRE