Nuclear Theory·nucl-th

Wednesday·October 17, 2018

12 papers—6 primary·6 cross-listed

01
[Submitted on 16 Oct 2018]
Squeezed back-to-back correlation between bosons and antibosons with different in-medium masses in high-energy heavy-ion collisions
Peng-Zhi Xu🇨🇳 · Wei-Ning Zhang🇨🇳 · Yong Zhang🇨🇳
We derive the formulas of the squeezed back-to-back correlation (SBBC) between a boson and antiboson with different in-medium masses in high-energy heavy-ion collisions. The influence of the in-medium mass difference between a boson and antiboson on the SBBC is investigated. We calculate the SBBC functions of $D$ -meson pairs for the hydrodynamic sources described by the VISH2+1 code for Au+Au collisions at $s_{N N} = 200$ ~GeV. Our results indicate that the SBBC strengths of $D^{+} D^{-}$ and $D^{0} D ˉ^{0}$ are different if there are charge-dependent in-medium interactions.
Comments:
5 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1810.06782 [pdf]
PRC(2019)·14 citations
02
[Submitted on 16 Oct 2018]
Symmetry-Based Approach to Shape Coexistence in Nuclei
A. Leviatan🇮🇱 · N. Gavrielov🇮🇱
A symmetry-based approach for describing shape-coexistence, is presented in the framework of the interacting boson model of nuclei. It involves a construction of a number-conserving Hamiltonian which preserves the dynamical symmetry of selected bands associated with each shape, while breaking the symmetries in other states. The resulting structure embodies multiple partial dynamical symmetries. The procedure is applied to prolate-oblate and spherical-prolate-oblate coexistence, at and slightly away from the critical points.
Comments:
12 pages, 5 figures, Final version, Proc. Int. Workshop on "Shapes and Dynamics of Atomic Nuclei: Contemporary Aspects" (SDANCA-17), October 5-7, 2017, Sofia, Bulgaria. arXiv admin note: substantial text overlap with arXiv:1708.06321, arXiv:1803.03982, arXiv:1605.00782
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1810.06804 [pdf]
Bulg.J.Phys.(2018)·0 citations
03
[Submitted on 16 Oct 2018]
Extrapolation of scattering data to the negative-energy region. Application to the $p -^{16}$ O system
L. D. Blokhintsev · A. S. Kadyrov · A. M. Mukhamedzhanov · D. A. Savin
The problem of analytic continuation of the scattering data to the negative-energy region to obtain information on asymptotic normalization coefficients (ANCs) of bound states is discussed. It is shown that a recently suggested $Δ$ method [O.L.Ram\'ırez Suárez and J.-M. Sparenberg, Phys. Rev. C {\bf 96}, 034601 (2017)] is not strictly correct in the mathematical sense since it is not an analytic continuation of a partial-wave scattering amplitude to the region of negative energies. However, it can be used for practical purposes for sufficiently large charges and masses of colliding particles. Both the $Δ$ method and the standard method of continuing of the effective range function are applied to the $p -^{16}$ O system which is of interest for nuclear astrophysics. The ANCs for the ground $5/ 2^{+}$ and excited $1/ 2^{+}$ states of $^{17}$ F are determined.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1810.06812 [pdf]
PRC(2018)·13 citations
04
[Submitted on 14 Oct 2018]
Effects of $Δ (1905) 5/ 2^{+}$ on $K^{*} Σ$ photoproduction
A. C. Wang🇨🇳 · W. L. Wang🇨🇳 · F. Huang🇨🇳
The two-channel photoproductions of $γ p \to K^{*+} Σ^{0}$ and $γ p \to K^{* 0} Σ^{+}$ are investigated based on an effective Lagrangian approach at the tree-level Born approximation. In addition to the $t$ -channel $K$ , $κ$ , $K^{*}$ exchanges, the $s$ -channel nucleon ( $N$ ) and $Δ$ exchanges, the $u$ -channel $Λ$ , $Σ$ , $Σ^{*}$ exchanges, and the generalized contact term, we try to take into account the minimum number of baryon resonances in constructing the reaction amplitudes to describe the experimental data. It is found that by including the $Δ (1905) 5/ 2^{+}$ resonance with its mass, width, and helicity amplitudes taken from the Review of Particle Physics [Particle Data Group, C. Patrignani {\it et al.}, Chin. Phys. C {\bf 40}, 100001 (2016)], the calculated differential and total cross sections for these two reactions are in good agreement with the experimental data. An analysis of the reaction mechanisms shows that the cross sections of $γ p \to K^{*+} Σ^{0}$ are dominated by the $s$ -channel $Δ (1905) 5/ 2^{+}$ exchange at low energies and $t$ -channel $K^{*}$ exchange at high energies, with the $s$ -channel $Δ$ exchange providing significant contributions in the near-threshold region. For $γ p \to K^{* 0} Σ^{+}$ , the angular dependences are dominated by the $t$ -channel $K$ exchange at forward angles and the $u$ -channel $Σ^{*}$ exchange at backward angles, with the $s$ -channel $Δ$ and $Δ (1905) 5/ 2^{+}$ exchanges making considerable contributions at low energies. Predictions are given for the beam, target, and recoil asymmetries for both reactions.
Comments:
11 pages, 8 figures, version published in PRC. arXiv admin note: text overlap with arXiv:1704.04562
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1810.07012 [pdf]
PRC(2018)·29 citations
05
[Submitted on 16 Oct 2018]
Can magnetic fields stabilize or destabilize twin stars?
R.O. Gomes🇩🇪 · V. Dexheimer🇺🇸 · S. Han🇺🇸 · S. Schramm🇩🇪
Sharp phase transitions described by stiff equations of state allow for the existence of a third family of stable compact stars (besides white dwarfs and neutron stars), twin stars. In this work, we investigate for the first time the role of strong magnetic fields on non-magnetic twin stars sequences and the case in which magnetic fields themselves give rise to a third family of stable stars. We use three sets of equations of state to study such effects from a more general point of view: the Quark-Hadron Chiral Parity-Doublet (Q $χ$ P) model for both hadronic and quark phases, and the Many-Body Forces (MBF) model connected to either the MIT Bag model with vector interaction (MIT) or to the Constant-Sound-Speed (CSS) approximation for the quark phase, through a Maxwell construction. Magnetic field effects are introduced in the structure of stars through the solution of the Einstein-Maxwell equations, assuming a poloidal magnetic field configuration and a metric that allows for the description of deformed stars. We show that strong magnetic fields can destabilize twin star sequences, with the threshold intensity being model dependent. On the other hand, magnetic fields can also give rise to twin stars in models that did not predict these sequences, up to some point when they are again destabilized. In this sense, magnetic fields can play an important role on the evolution of neutron stars.
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
1810.07046 [pdf]
MNRAS(2019)·29 citations
06
[Submitted on 16 Oct 2018]
Spin response and neutrino mean free path in neutron matter
Luca Riz🇮🇹 · Francesco Pederiva🇮🇹 · Stefano Gandolfi🇺🇸
The longitudinal and transverse density- and spin-density response functions in Pure Neutron Matter (PNM) are derived over a wide range of densities within the Time Dependent Local Spin Density Approximation (TDLSDA). The underlying density functional was derived from an Auxiliary Field Diffusion Monte Carlo (AFDMC) computation of the equation of state of unpolarized and fully spin polarized pure neutron matter. In order to assess the dependence of the results on the specific underlying nucleon-nucleon Hamiltonian, we used both the phenomenological Argonne AV8'+UIX force, and local chiral forces up to N2LO. The resulting response function has then been applied to the study of the neutrino mean free path in PNM.
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
1810.07110 [pdf]
J.Phys.G(2020)·12 citations
07
[Submitted on 15 Oct 2018] (cross-list from hep-ph)
Strong- vs. weak-coupling pictures of jet quenching: a dry run using QED
Peter Arnold🇺🇸 · Shahin Iqbal🇵🇰 · Tanner Rase🇺🇸
High-energy partons ( $E ≫ T$ ) traveling through a quark-gluon plasma lose energy by splitting via bremsstrahlung and pair production. Regardless of whether or not the quark-gluon plasma itself is strongly coupled, an important question lying at the heart of philosophically different approaches to energy loss is whether the high-energy partons of an in-medium shower can be thought of as a collection of individual particles, or whether their coupling to each other is also so strong that a description as high-energy `particles' is inappropriate. We discuss some possible theorists' tests of this question for simple situations (e.g. an infinite, non-expanding plasma) using thought experiments and first-principles quantum field theory calculations (with some simplifying approximations). The physics of in-medium showers is substantially affected by the Landau-Pomeranchuk-Midgal (LPM) effect, and our proposed tests require use of what might be called `next-to-leading order' LPM results, which account for quantum interference between consecutive splittings. The complete set of such results is not yet available for QCD but is already available for the theory of large- $N_{f}$ QED. We therefore use large- $N_{f}$ QED as an example, presenting numerical results as a function of $N_{f} α$ , where $α$ is the strength of the coupling at the relevant high-energy scale characterizing splittings of the high-energy particles.
Comments:
31 pages + appendices for 48 pages total, 21 figures. [Difference from version 2: Main change was to eliminate some summary formulas of NLO rates in section III.B, made unnecessary by a clear summary of formulas having been added to ref. [13].]
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1810.06578 [pdf]
JHEP(2019)·20 citations
08
[Submitted on 15 Oct 2018] (cross-list from hep-ph)
Virtual axion-like particle complement to Euler-Heisenberg-Schwinger action
Stefan Evans🇺🇸 · Johann Rafelski🇺🇸
We modify action in an external electromagnetic field to include effects of virtual axion-like particle (ALP) excitations. A measurable addition to QED-Euler-Heisenberg-Schwinger (EHS) action is obtained and incorporated into experimental constraints placed on ALP mass and coupling to two photons. The regime of these constraints in which the ALP vacuum effect surpasses the EHS effect is characterized. We show that probing of the virtual vacuum effect offers an alternative method in search for physics related to ALPs.
Comments:
5 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1810.06717 [pdf]
PLB(2019)·16 citations
09
[Submitted on 16 Oct 2018] (cross-list from hep-ph)
Systematic studies of charmonium-, bottomonium-, and $B_{c}$ -like tetraquark states
Jing Wu🇨🇳 · Xiang Liu🇨🇳 · Yan-Rui Liu🇨🇳 · Shi-Lin Zhu🇨🇳
We study the mass splittings of $Q_{1} q_{2} Q ˉ_{3} q ˉ_{4}$ ( $Q = c, b$ , $q = u, d, s$ ) tetraquark states with chromomagnetic interactions between their quark components. Assuming that $X (4140)$ is the lowest $J^{P C} = 1^{++}$ $cs c ˉ s ˉ$ tetraquark, we estimate the masses of the other tetraquark states. From the obtained masses and defined measure reflecting effective quark interactions, we find the following assignments for several exotic states: (1) both $X (3860)$ and the newly observed $Z_{c} (4100)$ seem to be $0^{++}$ $c n c ˉ n ˉ$ tetraquarks; (2) $Z_{c} (4200)$ is probably a $1^{+-}$ $c n c ˉ n ˉ$ tetraquark; (3) $Z_{c} (3900)$ , $X (3940)$ , and $X (4160)$ are unlikely compact tetraquarks; (4) $Z_{c} (4020)$ is unlikely a compact tetraquark, but seems the hidden-charm correspondence of $Z_{b} (10650)$ with $J^{P C} = 1^{+-}$ ; and (5) $Z_{c} (4250)$ can be a tetraquark candidate but the quantum numbers cannot be assigned at present. We hope further studies may check the predictions and assignments given here.
Comments:
23 pages, 5 figures, 13 tables. Version will appear in Phys. Rev. D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1810.06886 [pdf]
PRD(2019)·60 citations
10
[Submitted on 16 Oct 2018] (cross-list from hep-ph)
Remarks on the Heavy-Quark Flavour Symmetry for doubly heavy hadronic molecules
V. Baru🇩🇪 · E. Epelbaum🇩🇪 · J. Gegelia🇩🇪 · C. Hanhart🇩🇪 · U.-G. Meißner🇩🇪 · A. V. Nefediev🇷🇺
The possibility for a common effective field theory for hadronic molecules with different heavy-quark flavours is examined critically. It is argued that such a theory does not allow one to draw definite conclusions for doubly heavy molecules. In particular, it does not allow one to relate binding energies for the molecules in the c-quark and b-quark sectors with controlled uncertainties. Therefore, while this kind of reasoning does not preclude from employing heavy-quark spin symmetry for charmonium- and bottomonium-like states separately within a well established effective field theory framework, relations between different heavy-quark sectors can only be obtained using phenomenological approaches with uncontrolled uncertainties.
Comments:
7 pages, extended discussions, added references, version to appear in Eur. Phys. J. C
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1810.06921 [pdf]
EPJC(2019)·23 citations
11
[Submitted on 16 Oct 2018] (cross-list from hep-ph)
Bethe-Salpeter-Motivated Modelling of Pseudo-Goldstone Pseudoscalar Mesons
Wolfgang Lucha🇦🇹
We apply a description of bound states of fermion and antifermion by means of our approximation to the Bethe-Salpeter formalism that retains part of the information on relativistic effects provided by the full fermion propagator to the lightest pseudoscalar mesons. Therein, the pseudo-Goldstone nature of the latter quark-antiquark bound states is taken into account by appropriately formulated effective interactions. Scrutinizing the predictions of this bound-state approach for meson masses, decay constants and in-meson condensates by relying on a generalized Gell-Mann-Oakes-Renner relation shows that the light-quark-mass values required for agreement are all in the right ballpark.
Comments:
8 pages, 3 figures, contributed to "XIII Quark Confinement and the Hadron Spectrum - Confinement2018" (31 July - 6 August 2018, Maynooth University, Ireland)
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1810.06958 [pdf]
PoS(2018)·0 citations
12
[Submitted on 16 Oct 2018] (cross-list from nucl-ex)
Collective Effects in Nuclear Collisions: Experimental Overview
You Zhou🇩🇰
These conferences proceedings summarize the experimental findings of collective effects in nuclear collisions, as presented at the Quark Matter 2018 conference.
Comments:
Final version of proceedings for an invited overview talk in XXVIIth International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2018), Venezia, Italy
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1810.06978 [pdf]
NPA(2019)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE