Nuclear Theory·nucl-th

Wednesday·April 1, 2020

9 papers—3 primary·6 cross-listed

01
Study of $n +^{3}$ H, $p +^{3}$ He, $p +^{3}$ H, and $n +^{3}$ He scattering with the HH method
M. Viviani🇮🇹 · L. Girlanda🇮🇹 · A. Kievsky🇮🇹 · L.E. Marcucci🇮🇹
The $n +^{3}$ H, $p +^{3}$ He, $p +^{3}$ H, and $n +^{3}$ He elastic and charge exchange reactions at low energies are studied by means of the hyperspherical harmonic method. The considered nuclear Hamiltonians include modern two- and three-nucleon interactions, in particular results are reported in case of chiral two-nucleon potentials, with and without the inclusion of chiral three-nucleon (3N) interactions. A detailed study of the convergence and numerical stability of the method is presented. We have found that the effect the 3N force is in general tiny except for $p +^{3}$ H scattering below the opening of the $n +^{3}$ He channel. In such a case, the effect of 3N forces is appreciable and a clear dependence on the cutoff used to regularize the high-momentum tail of the interactions is observed. Such a dependence is related to the presence of the poorly known sharp $0^{+}$ resonance, considered to be the first excited state of $^{4}$ He.
nucl-th2 citations
02
Properties of $K^{π} = 0_{1}^{+}$ , $K^{π} = 2^{-}$ , and $K^{π} = 0_{1}^{-}$ bands of $^{20}$ Ne probed via proton and alpha inelastic scattering
Yoshiko Kanada-En'yo🇯🇵 · Kazuyuki Ogata🇯🇵
The $K^{π} = 0_{1}^{+}$ , $K^{π} = 2^{-}$ , and $K^{π} = 0_{1}^{-}$ bands of $^{20}$ Ne are investigated with microscopic structure and reaction calculations via proton and $α$ inelastic scattering off $^{20}$ Ne. Structures of $^{20}$ Ne are calculated with variation after parity and total angular momentum projections in the antisymmetrized molecular dynamics(AMD). The $K^{π} = 0_{1}^{+}$ and $K^{π} = 0_{1}^{-}$ bands have $^{16} O + α$ cluster structures, whereas the $K^{π} = 2^{-}$ band shows a $^{12} C + 2 α$ -like structure. Microscopic coupled-channel calculations of proton and $α$ scattering off $^{20}$ Ne are performed by using the proton-nucleus and $α$ -nucleus potentials, which are derived by folding the Melbourne $g$ -matrix $N N$ interaction with AMD densities of $^{20}$ Ne. The calculation reasonably reproduces the observed cross sections of proton scattering at $E_{p} = 25$ --35 MeV and $α$ scattering at $E_{α} = 104$ --386 MeV. Transition properties from the ground to excited states are discussed by reaction analyses of proton and $α$ inelastic processes. Mixing of the $K^{π} = 2^{-}$ and $K^{π} = 0_{1}^{-}$ bands is discussed by detailed analysis of the $0_{1}^{+} \to 3_{1}^{-}$ and $0_{1}^{+} \to 3_{2}^{-}$ transitions. For the $3_{1}^{-}$ state, mixing of the $K^{π} = 0_{1}^{-}$ cluster component in the $K^{π} = 2^{-}$ band plays an important role in the transition properties.
nucl-thPRC(2020)·19 citations
03
Light Neutral Clusters in Supernova Matter
I.V. Panov · A.V. Yudin
The role of weakly bound neutral clusters, such as dineutrons and tetraneutrons, in matter of high density and high temperature is discussed. Under such conditions, which are characteristic of core-collapse supernovae, the lifetime of multineutrons may prove to be sufficiently long for them to have a pronounced effect on the formation of the chemical composition. The influence of the multineutron binding energy and other nuclear properties on the magnitude of the effect being considered is examined.
nucl-thastro-ph.SRPhys.Atom.Nucl.(2019)·3 citations
04
Ultraperipheral nuclear interactions
I.M. Dremin🇷🇺
Large-distance ultraperipheral collisions of two relativistic ions are considered. The clouds of photons surrounding the ions are responsible for their distant electromagnetic interaction. The perturbative approach and the method of equivalent photons are described. It is shown that the total cross section of these collisions increases rapidly with increasing energy and is especially large for heavy ions. Some experimental data and their comparison with theoretical approaches are described. Further proposals are discussed.
↳ hep-phhep-exnucl-exnucl-thPhys.Usp.(2020)·7 citations
05
Core meets corona: a two-component source to explain Lambda and anti-Lambda global polarization in semi-central heavy-ion collisions
Alejandro Ayala🇲🇽 · Marco Alberto Ayala Torres🇲🇽 · Eleazar Cuautle🇲🇽 · Isabel Dominguez🇲🇽 · Marcos Aurelio Fontaine Sanchez🇲🇽 · Ivonne Maldonado🇲🇽 · E. Moreno-Barbosa🇲🇽 · P. A. Nieto-Marin🇲🇽 · M. Rodriguez-Cahuantzi🇲🇽 · Jordi Salinas🇲🇽 · Maria Elena Tejeda-Yeomans🇲🇽 · L. Valenzuela-Cazares🇲🇽
We compute the Lambda and anti-Lambda global polarization in semi-central heavy-ion collisions modeling the source as consisting of a high-density core and a less dense corona. We show that when more Lambdas than anti-Lambdas are produced in the corona, and this is combined with a smaller number of Lambdas coming from the core, as compared to those coming from the corona, an amplification effect for the anti-Lambda with respect to that of Lambda polarization can occur. This amplification becomes more important for lower collision energies and quantitatively accounts for the Lambda and anti-Lambda polarizations measured by the STAR beam energy scan.
↳ hep-phnucl-exnucl-thPLB(2020)·33 citations
06
Connecting fluctuation measurements in heavy-ion collisions with the grand-canonical susceptibilities
Volodymyr Vovchenko🇺🇸 · Oleh Savchuk🇺🇦 · Roman V. Poberezhnyuk🇺🇦 · Mark I. Gorenstein🇺🇦 · Volker Koch🇺🇸
We derive the relation between cumulants of a conserved charge measured in a subvolume of a thermal system and the corresponding grand-canonical susceptibilities, taking into account exact global conservation of that charge. The derivation is presented for an arbitrary equation of state, with the assumption that the subvolume is sufficiently large to be close to the thermodynamic limit. Our framework -- the subensemble acceptance method (SAM) -- quantifies the effect of global conservation laws and is an important step toward a direct comparison between cumulants of conserved charges measured in central heavy ion collisions and theoretical calculations of grand-canonical susceptibilities, such as lattice QCD. As an example, we apply our formalism to net-baryon fluctuations at vanishing baryon chemical potentials as encountered in collisions at the LHC and RHIC.
↳ hep-phnucl-exnucl-thPLB(2020)·85 citations
07
Topological term, QCD anomaly, and the eta' chiral soliton lattice in rotating baryonic matter
Kentaro Nishimura🇯🇵 · Naoki Yamamoto🇯🇵
We study the ground states of low-density hadronic matter and high-density color-flavor locked color superconducting phase in three-flavor QCD at finite baryon chemical potential under rotation. We find that, in both cases under sufficiently fast rotation, the combination of the rotation-induced topological term for the eta' meson and the QCD anomaly leads to an inhomogeneous condensate of the eta' meson, known as the chiral soliton lattice (CSL). We find that, when baryon chemical potential is much larger than isospin chemical potential, the critical angular velocity for the realization of the eta' CSL is much smaller than that for the pi_0 CSL found previously. We also argue that the eta' CSL states in flavor-symmetric QCD at low density and high density should be continuously connected, extending the quark-hadron continuity conjecture in the presence of the rotation.
↳ hep-phcond-mat.mes-hallhep-thnucl-thJHEP(2020)·43 citations
08
Valence-Quark Distribution of the Kaon and Pion from Lattice QCD
Huey-Wen Lin🇺🇸 · Jiunn-Wei Chen🇹🇼 · Zhouyou Fan🇺🇸 · Jian-Hui Zhang🇨🇳 · Rui Zhang🇺🇸
We present the first lattice-QCD calculation of the kaon valence-quark distribution functions using the large-momentum effective theory (LaMET) approach. The calculation is performed with multiple pion masses with the lightest one around 220 MeV, 2 lattice spacings $a = 0.06$ and 0.12 fm, $(M_{π})_{min} L \approx 5.5$ , and high statistics ranging from 11,600 to 61,312 measurements. We also calculate the valence-quark distribution of pion and find it to be consistent with the FNAL E615 experimental results, and our ratio of the $u$ quark PDF in the kaon to that in the pion agrees with the CERN NA3 experiment. We also make predictions of the strange-quark distribution of the kaon.
↳ hep-lathep-phnucl-thPRD(2021)·114 citations
09
Expression of relativistic expectation values of powers of $r$ in terms of Clebsch-Gordan coefficients
Jean-Christophe Pain🇫🇷
It is shown that, in the relativistic hydrogenic approximation, expectation values of the type $⟨ n ℓ j ∣ r^{k} ∣ n ℓ j ⟩$ can be expressed in terms of Clebsch-Gordan coefficients or $3 j m$ symbols. This generalizes the results obtained by Varshalovich and Karpova [Opt. Spectrosc. 118, 1-5 (2015); Opt. Spektrosk. 118, 3-7] in the non-relativistic hydrogenic case.
↳ quant-phnucl-thphysics.atom-phOpt.Spectrosc.(2020)·1 citation

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