Nuclear Theory·nucl-th

Friday·March 8, 2019

18 papers—7 primary·11 cross-listed

01
[Submitted on 6 Mar 2019]
Universal behavior of $p$ -wave proton-proton fusion near threshold
Bijaya Acharya🇩🇪 · Lucas Platter🇺🇸 · Gautam Rupak🇺🇸
We calculate the $p$ -wave contribution to the proton-proton fusion $S$ factor and its energy derivative in pionless effective field theory (EFT) up to next-to-leading order. The leading contributions are given by a recoil piece from the Gamow-Teller and Fermi operators, and from relativistic $1/ m$ suppressed weak interaction operators. We obtain the value of $(2.5 \pm 0.3) \times 1 0^{- 28} MeV f m^{2}$ for the $S$ factor and $(2.2 \pm 0.2) \times 1 0^{- 26} f m^{2}$ for its energy derivative at threshold. These are smaller than the results of a prior study that employed chiral EFT by several orders of magnitude. We conclude that, contrary to what has been previously reported, the $p$ -wave contribution does not need to be considered in a high-precision determination of the $S$ factor at astrophysical energies. Combined with the chiral EFT calculation of Acharya {\it et al.} [Phys. Lett. B \bf{760}, 584 (2016)] for the $s$ -wave channel, this gives a total threshold $S$ factor of $S (0) = (4.04 7_{- 0.032}^{+ 0.024}) \times 1 0^{- 23} MeV fm^{2}$ .
Comments:
5 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1903.02590 [pdf]
PRC(2019)·8 citations
02
[Submitted on 6 Mar 2019]
Scattering matrix pole expansions & invariance with respect to R-matrix parameters
Pablo Ducru🇺🇸 · Vladimir Sobes🇺🇸 · Gerald Hale🇺🇸 · Mark Paris🇺🇸 · Benoit Forget🇺🇸
Nuclear data libraries (ENDF, JEFF, JENDL, CENDL, etc.) document our phenomenological knowledge of nuclear cross sections as interpreted by R-matrix theory. The R-matrix scattering model can parameterize the energy dependence of the scattering matrix in different ways. This article establishes new results on three such sets of parameters: the Wigner-Eisenbud, the Brune, and the Siegert-Humblet parameters. We show how the latter two arise from invariance to the arbitrary boundary condition, and how they can trade-off more complex parameters for a simpler energy dependence parameterization: the scattering matrix pole expansion of Humblet and Rosenfeld. We establish that the scattering matrix's invariance to channel radius sets a partial differential equation on the widths of the Kapur-Peierls operator, which enables us to derive an explicit transformation of the Siegert-Humblet radioactive residue widths under a change of channel radius. Considering the continuation of the scattering matrix to complex wavenumbers, several new results are established. We unveil there exist more Brune parameters than previously thought, depending on the way the scattering matrix is continued to complex energies. This points to a broader conundrum in the field: how to analytically continue the scattering matrix while closing sub-threshold channels. We argue that, contrary to the Lane and Thomas legacy of force-closing sub-threshold channels which introduces spurious poles, analytic continuation is the physically correct way of defining the scattering matrix for complex wave numbers. To back this claim we establish thee results: analytic continuation cancels spurious poles, enforces the generalized unitarity conditions of Eden and Taylor, and closes massive particle channels below threshold by both quantum tunneling and from the definition of the cross section as the ratio of probability currents.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1903.02661 [pdf]
PRC(2021)·4 citations
03
[Submitted on 7 Mar 2019]
Photoproduction of charged final states in ultra-peripheral collisions and electroproduction at an electron-ion collider
Spencer. R. Klein🇺🇸 · Ya-Ping Xie🇨🇳
Ultra-peripheral collisions (UPCs) of relativistic ions are an important tool for studying photoproduction at high energies. Vector meson photoproduction is an important tool for nuclear structure measurements and other applications. A future electron-ion collider (EIC) will allow additional studies, using virtual photons with a wide range of $Q^{2}$ . We propose a significant expansion of the UPC and EIC photoproduction physics programs to include charged final states which may be produced via Reggeon exchange. We consider two examples: $a_{2}^{+} (1320)$ , which is a conventional $q q$ meson, and the exotic $Z_{c}^{+} (4430)$ state (modeled here as a tetraquark). The $Z_{c}^{+} (4430)$ cross-section depends on its internal structure, so photoproduction can test whether the $Z_{c}^{+} (4430)$ is a tetraquark or other exotic object. We calculate the rates and kinematic distributions for $γ p \to X^{+} n$ in $p A$ UPCs and $e p$ collisions at an EIC and in UPCs. The rates are large enough for detailed studies of these final states. Because the cross-section for Reggeon exchange is largest near threshold, the final state rapidity distribution depends on the beam energies. At high-energy colliders like the proposed LHeC or $p A$ collisions at the LHC, the final states are produced at far forward rapidities. For lower energy colliders, the systems are produced closer to mid-rapidity, within reach of central detectors.
Comments:
5 pages with 3 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1903.02680 [pdf]
PRC(2019)·29 citations
04
[Submitted on 7 Mar 2019]
On formal scattering theory for differential Faddeev equations
S.L. Yakovlev
The formal scattering theory is developed for the three-particle differential Faddeev equations. The theory is realised along the same line as in the standard two-body case. The solution of the scattering problem is expressed in terms of the matrix T-operator constructed from the matrix resolvent of the differential Faddeev equations. The relationships of the matrix T-operator with elements of transition operators and Faddeev T-matrix components have been established.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1903.02946 [pdf]
Few Body Syst.(2019)·0 citations
05
[Submitted on 7 Mar 2019]
Hybrid Stars in the Framework of the Local Nambu - Jona-Lasinio Model for Quark Matter
G. B. Alaverdyan🇦🇲 · Yu. L. Vartanyan🇦🇲
The integral parameters of neutron stars are studied taking into account the hadron-quark phase transition, which leads to the formation of a core of quark matter in the central part of a star. The quark matter is described using the local Nambu - Jona-Lasinio (NJL) model. The thermodynamic characteristics of the hadron matter are calculated in the framework of an extended version of the relativistic mean field (RMF) model that includes the contribution of the scalar-isovector $δ$ -meson effective field. A Maxwell construction is used to determine the parameters of the phase transition. It is shown that for the equation of state examined here, stable hybrid stars correspond to a narrow range of values for the central density. In our model hybrid stars lie on the same branch as neutron stars, so that a branch with a third family is not formed. It is shown that for the equation of state examined here, stable hybrid stars correspond to a narrow range of values for the central density $ρ_{c} \in (1.71 \div 1.73] \cdot 1 0^{15}$ g/cm $^{3}$ . In our model hybrid stars lie on the same branch as neutron stars, so that a branch with a third family is not formed. The maximum mass of a stable hybrid star is found to be $M_{ma x} = 2.05 M_{⊙}$ . The configuration with the maximum mass has a quark core with mass $M_{cor e} \approx 1 0^{- 3} M_{⊙}$ and radius $R_{cor e} \approx 0.6$ km.
Comments:
16 pages, 3 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1903.02957 [pdf]
Astrophysics(2018)·5 citations
06
[Submitted on 7 Mar 2019]
Effect of in-medium mass-shift on transverse-momentum spectrum and elliptic anisotropy of $ϕ$ meson
Yong Zhang🇨🇳 · Jing Yang🇨🇳 · Weihua Wu🇨🇳
We study the effect of in-medium mass-shift on transverse-momentum spectrum and elliptic anisotropy of $ϕ$ meson. It is found that the mass-shift enhances the $ϕ$ yields and suppresses the elliptic flow $v_{2}$ in large momentum region, and the effects increase with the increasing mass-shift. The effects are various for different sources and decrease with the increasing expanding velocity. We further study the effects for parts of all $ϕ$ meson with mass-shift, and the effects decrease with the decreasing probability of $ϕ$ meson with mass-shift. Since the different mass-shift lead to different transverse-momentum spectrum and $v_{2}$ , our study may provide a way to restrict the ranges of in-medium mass-shift of $ϕ$ meson in high-energy heavy-ion collisions.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1903.02997 [pdf]
IJMPE(2020)·5 citations
07
[Submitted on 7 Mar 2019]
Pairing effects on neutron matter equation of state and symmetry energy at subsaturation densities
Zhen Zhang · Lie-Wen Chen
Within the framework of BCS theory and Skyrme-Hartree-Fock model, we employ various microscopic pairing gaps and effective pairing interactions to study pairing effects on the equation of state (EOS) of neutron matter and the symmetry energy at subsaturation densities. We find pairing effects may have considerable contributions to the EOS of neutron matter at very low densities ( $≲ 0.02 fm^{- 3}$ ), while only have a small impact on the symmetry energy at subsatruation densities. In addition, the reliability of the parabolic approximation for the isospin asymmetry dependence of nuclear matter EOS with pairing correlations included is also discussed.
Comments:
6 pages, 3 figures. Some results updated and discussions added. Accepted version to appear in PRC
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1903.03057 [pdf]
PRC(2019)·4 citations
08
[Submitted on 24 Sept 2018] (cross-list from hep-ph)
A Novel Approach to Neutrino-Hydrogen Measurements
H. Duyang🇺🇸 · B. Guo🇺🇸 · S.R. Mishra🇺🇸 · R. Petti🇺🇸
The limited statistics of the available (anti)neutrino-hydrogen (H) interactions has been a longstanding impediment for high-energy neutrino physics. We discuss a practical way to achieve accurate (anti)neutrino-hydrogen measurements, addressing the principal limitations of earlier experiments. Interactions on hydrogen are extracted by subtracting measurements on thin dedicated graphite (pure C) and polypropylene (CH $_{2}$ ) targets within a highly segmented low-density detector. A kinematic selection is used to increase the purities to 80-95\% before subtraction. A statistics of $O (1 0^{6})$ can be realistically achieved in modern neutrino beams for the various $ν (ν ˉ)$ -H event topologies. The availability of such samples would allow a precise determination of neutrino and antineutrino fluxes, as well as to directly constrain nuclear effects from a comparison with corresponding measurements on heavy materials within the same detector. The (anti)neutrino fluxes and the nuclear smearing are typically the leading sources of systematic uncertainties in long-baseline oscillation experiments. (Anti)neutrino-hydrogen interactions also provide an ideal tool for a wide range of precision tests of fundamental interactions.
Comments:
Final published version, 21 pages, 8 figures, 3 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); Instrumentation and Detectors (physics.ins-det)
arXiv:
1809.08752 [pdf]
Eur.Phys.J.Plus(2024)·31 citations
09
[Submitted on 25 Feb 2019] (cross-list from hep-ph)
A Precise Determination of (Anti)neutrino Fluxes with (Anti)neutrino-Hydrogen Interactions
H. Duyang🇺🇸 · B. Guo🇺🇸 · S.R. Mishra🇺🇸 · R. Petti🇺🇸
We present a novel method to accurately determine the flux of neutrinos and antineutrinos, one of the dominant systematic uncertainty affecting current and future long-baseline neutrino experiments, as well as precision neutrino scattering experiment. Using exclusive topologies in $ν (ν ˉ)$ -hydrogen interactions, $ν_{μ} p \to μ^{-} p π^{+}$ , $ν ˉ_{μ} p \to μ^{+} p π^{-}$ , and $ν ˉ_{μ} p \to μ^{+} n$ with small hadronic energy, we achieve an overall accuracy on the relative fluxes better than 1\% in the energy range covering most of the available flux. Since we cannot rely on simulations nor model corrections at this level of precision, we present techniques to constrain all relevant systematic uncertainties using data themselves. The method can be implemented using the approach we recently proposed to collect high statistics samples of $ν (ν ˉ)$ -hydrogen interactions in a low-density and high-resolution detector, which could serve as part of the near detector complex in a long-baseline neutrino experiment, as well as a dedicated beam monitoring detector.
Comments:
Final version published in PLB (15 pages, 7 figures, 2 tables)
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); Instrumentation and Detectors (physics.ins-det)
arXiv:
1902.09480 [pdf]
PLB(2019)·32 citations
10
[Submitted on 25 Feb 2019] (cross-list from hep-th)
Relativistic Hydrodynamic Fluctuations
Xin An🇺🇸 · Gokce Basar🇺🇸 · Mikhail Stephanov🇺🇸 · Ho-Ung Yee🇺🇸
We present a general systematic formalism for describing dynamics of fluctuations in an arbitrary relativistic hydrodynamic flow, including their feedback (known as long-time hydrodynamic tails). The fluctuations are described by two-point equal-time correlation functions. We introduce a definition of equal time in a situation where the local rest frame is determined by the local flow velocity, and a method of taking derivatives and Wigner transforms of such equal-time correlation functions, which we call confluent. We find that the equations for confluent Wigner functions not only resemble kinetic equations, but that the kinetic equation for phonons propagating on an arbitrary background nontrivially matches the equations for Wigner functions, including relativistic inertial and Coriolis forces due to acceleration and vorticity of the flow. We also describe the procedure of renormalization of short-distance singularities which eliminates cutoff dependence, allowing efficient numerical implementation of these equations.
Comments:
29 pages, 3 figures; typos corrected and some notations optimized
Subjects:
High Energy Physics — Theory (hep-th); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1902.09517 [pdf]
PRC(2019)·93 citations
11
[Submitted on 4 Mar 2019] (cross-list from gr-qc)
Dark compact objects: an extensive overview
Maksym Deliyergiyev🇨🇳 · Antonino Del Popolo🇮🇹 · Laura Tolos🇩🇪 · Morgan Le Delliou🇨🇳 · Xiguo Lee🇨🇳 · Fiorella Burgio🇮🇹
We study the structure of compact objects that contain non-self annihilating, self-interacting dark matter admixed with ordinary matter made of neutron star and white dwarf materials. We extend the previous work Phys. Rev. D 92 123002 (2015) on these dark compact objects by analyzing the effect of weak and strongly interacting dark matter with particle masses in the range of 1-500 GeV, so as to set some constraints in the strength of the interaction and the mass of the dark matter particle. We find that the total mass of the compact objects increases with decreasing dark matter particle mass. In the strong interacting case and for dark matter particle masses in the range 1-10 GeV, the total mass of the compact objects largely exceeds the $2 M_{⊙}$ constraint for neutron star masses and the nominal $1 M_{⊙}$ for white dwarfs, while for larger dark matter particle masses or in the weakly interacting case the compact objects show masses in agreement or smaller than these constraints, thus hinting at the exclusion of strongly self-interacting dark matter of masses 1-10 GeV in the interior of these compact objects. Moreover, we observe that the smaller the dark matter particle mass, the larger the quantity of dark matter captured is, putting constraints on the dark matter mass trapped in the compact objects so as to fullfill $≃ 2 M_{⊙}$ observations. Finally, the inhomogeneity of distribution of dark matter in the Galaxy implies a mass dependence of compact objects from the environment which can be used to put constraints on the characteristics of the Galaxy halo DM profile and on particle mass. In view of the these results, we discuss the formation of the dark compact objects in an homogeneous and non-homogeneous dark matter environment.
Comments:
17pp, 11 figs, PRD in print
Subjects:
General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1903.01183 [pdf]
PRD(2019)·94 citations
12
[Submitted on 6 Mar 2019] (cross-list from hep-ph)
Photon radiation in hot nuclear matter by means of chiral anomalies
Kirill Tuchin🇺🇸
A new mechanism of photon emission in the quark-gluon plasma is proposed. Photon dispersion relation in the presence of the $C P$ -odd topological regions generated by the chiral anomaly acquires an imaginary mass. It allows photon radiation through the decay $q \to q γ$ and annihilation $q q ˉ \to γ$ processes closely related to the chiral Cherenkov radiation. Unlike previous proposals this mechanism does not require an external magnetic field. The differential photon emission rate per unit volume is computed and shown to be comparable to the rate of photon emission in conventional processes.
Comments:
12 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1903.02629 [pdf]
PRC(2019)·9 citations
13
[Submitted on 7 Mar 2019] (cross-list from hep-ph)
Confinement from Correlated Instanton-Dyon Ensemble in SU(2) Yang-Mills Theory
Miguel Angel Lopez-Ruiz🇺🇸 · Yin Jiang🇨🇳 · Jinfeng Liao🇺🇸
We study the confinement phase transition in $S U (2)$ Yang-Mills theory, based on a statistical ensemble model of correlated instanton-dyons. We show for the first time that such a model provides a quantitative description, in light of the lattice data, for the temperature dependence of the order parameter. We characterize the short-range interaction which plays a crucial role for the properties of such ensemble. The chromo-magnetic charge density as well as the spatial correlations is found to be consistent with known lattice and phenomenological information.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1903.02684 [pdf]
PRD(2019)·4 citations
14
[Submitted on 7 Mar 2019] (cross-list from hep-ph)
Gravitational form factors of a spin one particle
Maxim V. Polyakov🇷🇺 · Bao-Dong Sun🇨🇳
We define the form factors of the quark and gluon symmetric energy-momentum tensor (EMT). The static EMT is related to the spatial distributions of energy, spin, pressure and shear forces. They are obtained in the form of a multipole expansion. The relations between gravitational form factors and the generalised parton distributions are given.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1903.02738 [pdf]
PRD(2019)·71 citations
15
[Submitted on 7 Mar 2019] (cross-list from nucl-ex)
Liquid-Gas phase transition in nuclei
B. Borderie🇫🇷 · J.D. Frankland🇫🇷
This review article takes stock of the progress made in understanding the phase transition in hot nuclei and highlights the coherence of observed signatures
Comments:
review article, 97 pages, 50 figures
Subjects:
Nuclear Experiment (nucl-ex); Statistical Mechanics (cond-mat.stat-mech); Nuclear Theory (nucl-th)
arXiv:
1903.02881 [pdf]
PPNP(2019)·75 citations
16
[Submitted on 7 Mar 2019] (cross-list from hep-ph)
Bound states of relativistic nature
V.A. Karmanov🇷🇺 · J. Carbonell🇫🇷 · H. Sazdjian🇫🇷
Bethe-Salpeter equation, for massless exchange and large fine structure constant $α > π /4$ , in addition to the Balmer series, provides another (abnormal) series of energy levels which are not given by the Schrödinger equation. So strong field can be created by a point-like charge $Z > 107$ . The nuclei with this charge, though available, they are far from to be point-like that weakens the field. Therefore, the abnormal states of this origin hardly exist. We analyze the more realistic case of exchange by a massive particle when the large value of coupling constant is typical for the strong interaction. It turns out that this interaction still generates a series of abnormal relativistic states. The properties of these solutions are studied. Their existence in nature seems possible.
Comments:
13 pages, 10 figures, to be published in Proceedings of the International Conference: Nuclear Theory in the Supercomputing Era-2018 (NTSE-2018), Daejeon, South Korea, October 29 - November 2, 2018; eds. A. M. Shirokov and A. I. Mazur. Pacific National University, Khabarovsk, Russia, 2019
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1903.02892 [pdf]
2 citations
17
[Submitted on 7 Mar 2019] (cross-list from hep-ph)
Another walk through the world of chiral dynamics
Ulf-G. Meißner🇩🇪
Chiral dynamics is a pretty mature field. Nonetheless, there are many exciting new developments. In this opening talk, I consider S-wave, isospin-zero pion-pion scattering and the calculation of the width of the lightest baryon resonances at two loops. New insights into the chiral dynamics of charm-strange mesons are discussed as well as recent results on the flavor decomposition of the pion-nucleon $σ$ -term. I end with a short wish-list of lattice QCD tests pertinent to chiral dynamics.
Comments:
Opening talk, The 9th International Workshop on Chiral Dynamics, September 17 -21, 2018, Duke University, Durham, North Carolina, USA
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1903.02898 [pdf]
PoS(2019)·2 citations
18
[Submitted on 7 Mar 2019] (cross-list from hep-ph)
Low-momentum pion enhancement from schematic hadronization of a gluon-saturated initial state
Elizaveta Nazarova🇷🇺 · Łukasz Juchnowski🇵🇱 · David Blaschke🇵🇱 · Tobias Fischer🇵🇱
We study the particle production in the early stage of the ultrarelativistic heavy-ion collisions. To this end the Boltzmann kinetic equations for gluons and pions with elastic rescattering are considered together with a simple model for the parton-hadron conversion process (hadronisation). It is shown that the overpopulation of the gluon phase space in the initial state leads to an intermediate stage of Bose enhancement in the low-momentum gluon sector which due to the gluon-pion conversion process is then reflected in the final distribution function of pions. This pattern is very similar to the experimental finding of a low-momentum pion enhancement in the ALICE experiment at CERN LHC. Relations to the thermal statistical model of hadron production and the phenomenon of thermal and chemical freeze-out are discussed in this context.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1903.03025 [pdf]
Particles(2019)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE