Nuclear Theory·nucl-th

Monday·January 27, 2020

16 papers—7 primary·9 cross-listed

01
Dynamics of critical fluctuations: Theory -- phenomenology -- heavy-ion collisions
M. Bluhm🇫🇷 · M. Nahrgang🇨🇭 · A. Kalweit🇫🇷 · M. Arslandok🇩🇪 · P. Braun-Munzinger🇩🇪 · S. Floerchinger🇩🇪 · E.S. Fraga🇧🇷 · M. Gazdzicki🇵🇱 · C. Hartnack🇫🇷 · C. Herold🇹🇭 · R. Holzmann🇩🇪 · Iu. Karpenko🇫🇷 and 18 other authors
This report summarizes the presentations and discussions during the Rapid Reaction Task Force "Dynamics of critical fluctuations: Theory -- phenomenology -- heavy-ion collisions", which was organized by the ExtreMe Matter Institute EMMI and held at GSI, Darmstadt, Germany in April 2019. We address the current understanding of the dynamics of critical fluctuations in QCD and their measurement in heavy-ion collision experiments. In addition, we outline what might be learned from studying correlations in other physical systems, such as cold atomic gases.
nucl-thhep-phnucl-exNPA(2020)·126 citations
02
Single $Λ_{c}^{+}$ hypernuclei within quark mean-field model
Linzhuo Wu🇨🇳 · Jinniu Hu🇨🇳 · Hong Shen🇨🇳
The quark mean-field (QMF) model is applied to study the single $Λ_{c}^{+}$ hypernuclei. The charm baryon, $Λ_{c}^{+}$ , is constructed by three constituent quarks, $u, d$ , and $c$ , confined by central harmonic oscillator potentials. The confinement potential strength of charm quark is determined by fitting the experimental masses of charm baryons, $Λ_{c}^{+}, Σ_{c}^{+}$ , and $Ξ_{cc}^{++}$ . The effects of pions and gluons are also considered to describe the baryons at the quark level. The baryons in $Λ_{c}^{+}$ hypernuclei interact with each other through exchanging the $σ, ω$ , and $ρ$ mesons between the quarks confined in different baryons. The $Λ_{c}^{+} N$ potential in the QMF model is strongly dependent on the coupling constant between $ω$ meson and $Λ_{c}^{+}$ , $g_{ω Λ_{c}^{+}}$ . When the conventional quark counting rule is used, i. e., $g_{ω Λ_{c}^{+}} = 2/3 g_{ω N}$ , the massive $Λ_{c}^{+}$ hypernucleus can exist, whose single $Λ_{c}^{+}$ binding energy is smaller with the mass number increasing due to the strong Coulomb repulsion between $Λ_{c}^{+}$ and protons. When $g_{ω Λ_{c}^{+}}$ is fixed by the latest lattice $Λ_{c}^{+} N$ potential, the $Λ_{c}^{+}$ hypernuclei only can exist up to $A \sim 50$ .
nucl-thPRC(2020)·7 citations
03
Resonances in Exotic $^{7}$ He Nucleus within the No-Core Shell Model
I. A. Mazur · A. M. Shirokov · I. J. Shin · A. I. Mazur · Y. Kim · P. Maris · J. P. Vary
We present results of calculations of $n -^{6} He$ elastic scattering phase shifts and resonances in $^{7} He$ . The calculations utilize the SS-HORSE method combined with ab initio no-core shell model calculations of the $^{7} He$ and $^{6} He$ nuclei with Daejeon16 and the JISP16 $N N$ interactions.
nucl-th6 citations
04
Modeling neutrino-nucleus interaction at intermediate energies
R. González-Jiménez🇧🇪 · N. Jachowicz🇧🇪 · A. Nikolakopoulos🇧🇪 · J. Nys🇧🇪 · T. Van Cuyck🇧🇪 · N. Van Dessel🇧🇪 · K. Niewczas🇧🇪 · V. Pandey🇺🇸
We present the current status of the research activities of the Ghent group on neutrino-nucleus interactions. These consist in the modeling of some of the relevant neutrino-nucleus reaction channels at intermediate energies: low-energy nuclear excitations, quasielastic scattering, two-nucleon knockout processes and single-pion production. The low-energy nuclear excitations and the quasielastic peak are described using a Hartree-Fock-CRPA (continuum random phase approximation) model that takes into account nuclear long-range correlations as well as the distortion of the outgoing nucleon wave function. We include two-body current mechanisms through short-range correlations and meson-exchange currents. Their influence on one- and two-nucleon knockout responses is computed. Bound and outgoing nucleons are treated within the same mean-field framework. Finally, for modeling of the neutrino-induced single-pion production, we use a low-energy model that contains resonances and the background contributions required by chiral symmetry. This low-energy model is combined with a Regge approach into a Hybrid model, which allows us to make predictions beyond the resonance region.
nucl-thPoS(2017)·2 citations
05
Peculiarity of the $^{12}$ C $(0^{+})$ and $^{12}$ C $(2^{+})$ energy spectrum in a 3 $α$ model
E.M. Tursunov · I. Mazumdar
Lowest energy spectrum of the $^{12}$ C nucleus is analyzed in the 3 $α$ cluster model with a deep $α α$ -potential of Buck, Friedrich and Wheatley with Pauli forbidden states in the $S$ and $D$ waves. The direct orthogonalization method is applied for the elimination of the 3 $α$ -Pauli forbidden states. The effects of possible first order quantum phase transition are shown in the lowest $^{12}$ C( $0_{1}^{+})$ and $^{12}$ C( $2_{1}^{+})$ states from weakly bound phase to a deep phase. The ground and lowest $2^{+}$ states of the $^{12}$ C nucleus in the deep phase are created by the critical eigen states of the Pauli projector for the $0^{+}$ and $2^{+}$ three-alpha functional spaces, respectively.
nucl-thnucl-exPhys.Atom.Nucl.(2022)·9 citations
06
Parity- and time-reversal-violating nuclear forces
J. de Vries🇺🇸 · E. Epelbaum🇩🇪 · L. Girlanda🇮🇹 · A. Gnech🇮🇹 · E. Mereghetti🇺🇸 · M. Viviani🇮🇹
Parity-violating and time-reversal conserving (PVTC) and parity-violating and time-reversal-violating (PVTV) forces in nuclei form only a tiny component of the total interaction between nucleons. The study of these tiny forces can nevertheless be of extreme interest because they allow to obtain information on fundamental symmetries using nuclear systems. The PVTC interaction derives from the weak interaction between the quarks inside nucleons and nuclei and the study of PVTC effects opens a window on the quark-quark weak interaction. The PVTV interaction is sensitive to more exotic interactions at the fundamental level, in particular to strong CP violation in the Standard Model Lagrangian, or even to exotic phenomena predicted in various beyond-the-Standard-Model scenarios. The presence of these interactions can be revealed either by studying various asymmetries in polarized scattering of nuclear systems, or by measuring the presence of non-vanishing permanent electric dipole moments of nucleons, nuclei and diamagnetic atoms and molecules. In this contribution, we review the derivation of the nuclear PVTC and PVTV interactions within various frameworks. We focus in particular on the application of chiral effective field theory, which allows for a more strict connection with the fundamental interactions at the quark level. We investigate PVTC and PVTV effects induced by these potential on several few-nucleon observables, such as the longitudinal asymmetry in proton-proton scattering and radiative neutron-proton capture, and the electric dipole momentsof the deuteron and the trinucleon system.
nucl-thhep-phnucl-exFront.in Phys.(2020)·54 citations
07
Hydrodynamic generators in relativistic kinetic theory
Mike McNelis🇺🇸 · Ulrich Heinz🇺🇸
We resum the non-equilibrium gradient corrections to a single-particle distribution function evolved by the Boltzmann equation in the relaxation time approximation (RTA). We first study a system undergoing Bjorken expansion and show that, for a constant relaxation time, the exact solution of the RTA Boltzmann equation at late times (i.e. after the decay of non-hydrodynamic modes) generates the Borel resummed Chapman-Enskog series. Extending this correspondence to systems without Bjorken symmetry, we construct a (3+1)-dimensional hydrodynamic generator for RTA kinetic theory, which is an integral representation of the Chapman-Enskog series in the limit of vanishing non-hydrodynamic modes. Relaxing this limit we find at earlier times a set of non-hydrodynamic modes coupled to the Chapman-Enskog expansion. Including the dynamics of these non-hydrodynamic modes is shown to control the emergence of hydrodynamics as an effective field theory description of non-equilibrium fluids, which works well even for far-off-equilibrium situations where the Knudsen number is initially large.
nucl-thPRC(2020)·15 citations
08
Skewness, kurtosis and the 5th and 6th order cumulants of net baryon-number distributions from lattice QCD confront high-statistics STAR data
A. Bazavov🇺🇸 · D. Bollweg🇩🇪 · H.-T. Ding🇨🇳 · P. Enns🇩🇪 · J. Goswami🇩🇪 · P. Hegde🇮🇳 · O. Kaczmarek🇨🇳 · F. Karsch🇩🇪 · R. Larsen🇺🇸 · Swagato Mukherjee🇺🇸 · H. Ohno🇯🇵 · P. Petreczky🇺🇸 and 3 other authors
We present new results on up to $6^{t h}$ order cumulants of net baryon-number fluctuations at small values of the baryon chemical potential, $μ_{B}$ , obtained in lattice QCD calculations with physical values of light and strange quark masses. Representation of the Taylor expansions of higher order cumulants in terms of the ratio of the two lowest order cumulants, $M_{B} / σ_{B}^{2} = χ_{1}^{B} (T, μ_{B}) / χ_{2}^{B} (T, μ_{B})$ , allows for a parameter free comparison with data on net proton-number cumulants obtained by the STAR Collaboration in the Beam Energy Scan at RHIC. We show that recent high statistics data on skewness and kurtosis ratios of net proton-number distributions, obtained at beam energy $s_{_{N N}} = 54.4$ GeV, agree well with lattice QCD results on cumulants of net baryon-number fluctuations close to the pseudo-critical temperature, $T_{p c} (μ_{B})$ , for the chiral transition in QCD. We also present first results from a next-to-leading order expansion of $5^{t h}$ and $6^{t h}$ order cumulants on the line of pseudo-critical temperatures.
↳ hep-lathep-phnucl-exnucl-thPRD(2020)·211 citations
09
Characterizing $r$ -Process Sites through Actinide Production
Erika M. Holmbeck · Rebecca Surman · Anna Frebel · G. C. McLaughlin · Matthew R. Mumpower · Trevor M. Sprouse · Toshihiko Kawano · Nicole Vassh · Timothy C. Beers
Of the variations in the elemental abundance patterns of stars enhanced with $r$ -process elements, the variation in the relative actinide-to-lanthanide ratio is among the most significant. We investigate the source of these actinide differences in order to determine whether these variations are due to natural differences in astrophysical sites, or due to the uncertain nuclear properties that are accessed in $r$ -process sites. We find that variations between relative stellar actinide abundances is most likely astrophysical in nature, owing to how neutron-rich the ejecta from an $r$ -process event may be. Furthermore, if an $r$ -process site is capable of generating variations in the neutron-richness of its ejected material, then only one type of $r$ -process site is needed to explain all levels of observed relative actinide enhancements.
↳ astro-ph.HEnucl-thJ.Phys.Conf.Ser.(2020)·3 citations
10
Comparative analysis of $ω p$ , $ϕp$ , and $J / ψ p$ scattering lengths from A2, CLAS, and GlueX threshold measurements
Igor Strakovsky (GWU)🇺🇸 · Lubomir Pentchev (JLab)🇺🇸 · Alexander Titov (JINR)🇷🇺
The high accuracy $ϕ$ -meson photoproduction data from the CLAS experiment in Hall~B of Jefferson Laboratory allow us to determine the near-threshold total cross section of the $γ p \to ϕp$ reaction and use it for evaluating the $ϕp$ scattering length $α_{ϕp}$ . These data result in an absolute value of $∣ α_{ϕp} ∣ = (0.063 \pm 0.010)$ ~fm, which is smaller than the typical hadron size. A comparative analysis of $α_{ϕp}$ with the previously determined scattering lengths for $ω p$ and $J / ψ p$ from the A2 and GlueX experiments is performed.
↳ hep-phhep-exnucl-exnucl-thPRC(2020)·56 citations
11
Role of interaction on electrical conductivity of QGP in presence of magnetic field
Ankita Mishra🇮🇳 · Souvik Paul🇮🇳 · Jayanta Dey🇮🇳 · Sarthak Satapathy🇮🇳 · Sabyasachi Ghosh🇮🇳
Effect of quantum chromodynamics (QCD) interaction in quark-gluon plasma on electrical conductivity is studied, where lattice quantum chromodynamics (LQCD) results are mapped through quark and gluon degeneracy.
↳ hep-phnucl-thDAE Symp.Nucl.Phys.(2019)·0 citations
12
Causal aspects of effective QCD models
Jayanta Dey🇮🇳 · Sabyasachi Ghosh🇮🇳 · Chowdhury Aminul Islam🇮🇳
Here we studied the possible diffusion speed for relativistic fluid in different effective quantum chromodynamics models: Nambu-Jona-Lasinio (NJL), Polyakov loop extended NJL, entangled PNJL (EPNJL) model.
↳ hep-phnucl-thDAE Symp.Nucl.Phys.(2019)·0 citations
13
Deuteron-induced reactions on manganese at low energies
M. Avrigeanu · E. Simeckova · U. Fischer · J. Mrazek · J. Novak · M. Stefanik · C. Costache · V. Avrigeanu
The scarce data systematics and complexity of deuteron interactions demand the update of both the experimental database and theoretical frame of deuteron activation cross sections. Various reactions induced by neutrons and protons following the deuteron breakup (BU) should be also taken into account. On the other hand, deuteron reaction cross sections recommended recently for high-priority elements are still based on data fit without predictive power. Purpose: Accurate new measurements of low-energy deuteron-induced reaction cross sections for monoisotopic (55Mn) natural manganese target enhance the related database as well as the opportunity of an unitary and consistent account of the related reaction mechanisms. Method: Activation cross sections of 54,56Mn, and 51Cr nuclei by deuterons on $^{55}$ Mn were measured at energies <20 MeV by the stacked-foil technique and high resolution gamma spectrometry at the U-120M cyclotron of CANAM, NPI CAS. Then all available data for deuterons on 55Mn up to 50 MeV are analyzed paying particular attention to BU and direct reaction (DR) mechanisms. Results: Newly measured activation cross sections strengthen the deuteron database at low energies, at once with a consistent account for the first time of all available data. Conclusions: Due account of deuteron-induced reactions on 55Mn, including particularly the new experimental data at low energies, is provided by a suitable BU and DR assessment.
↳ nucl-exnucl-thPRC(2020)·6 citations
14
\nu \bar{\nu} -Pair Synchrotron Emission in Neutron-Star Matter based on a Relativistic Quantum Approach
Tomoyuki Maruyama A. Baha Balantekin · Myung-Ki Cheoun · Toshitaka Kajino · Grant J. Mathews
We study the neutrino anti-neutrino pair synchrotron emission from electrons and protons in a relativistic quantum approach. This process occurs only under a strong magnetic field, and it is considered to be one of effective processes for neutron star cooling. In this work we calculate the luminosity of the neutrino anti-neutrino pairs emitted from neutron-star-matter with a magnetic field of about 10^{15} G. We find that the energy loss is much larger than that of the modified Urca process. The neutrino anti-neutrino pair emission processes in strong magnetic fields is expected to contribute significantly to the cooling of the magnetars.
↳ hep-phnucl-thPLB(2020)·6 citations
15
Shape coexistence in the neutron-deficient $^{188}$ Hg investigated via lifetime measurements
M. Siciliano🇮🇹 · I. Zanon🇮🇹 · A. Goasduff🇮🇹 · P.R. John🇮🇹 · T.R. Rodríguez🇪🇸 · S. Péru🇫🇷 · I. Deloncle🇫🇷 · J. Libert🇫🇷 · M. Zielińska🇫🇷 · D. Ashad🇮🇹 · D. Bazzacco🇮🇹 · G. Benzoni🇮🇹 and 32 other authors
Shape coexistence in the $Z \approx 82$ region has been established in mercury, lead and polonium isotopes. Even-even mercury isotopes with $100 \leq N \leq 106$ present multiple fingerprints of this phenomenon, which seems to be no longer present for $N \geq 110$ . According to a number of theoretical calculations, shape coexistence is predicted in the $^{188}$ Hg isotope. The $^{188}$ Hg nucleus was populated using two different fusion-evaporation reactions with two targets, $^{158}$ Gd and $^{160}$ Gd, and a beam of $^{34}$ S, provided by the Tandem-ALPI accelerators complex at the Laboratori Nazionali di Legnaro. The channels of interest were selected using the information from the Neutron Wall array, while the $γ$ rays were detected using the GALILEO $γ$ -ray array. The lifetimes of the excited states were determined using the Recoil Distance Doppler-Shift method, employing the dedicated GALILEO plunger device. Using the two-bands mixing and rotational models, the deformation of the pure configurations was obtained from the experimental results. The extracted transition strengths were compared with those calculated with the state-of-the-art symmetry-conserving configuration-mixing (SCCM) and five-dimentional collective Hamiltonian (5DCH) approaches in order to shed light on the nature of the observed structures in the $^{188}$ Hg nucleus. An oblate, a normal- and a super-deformed prolate bands were predicted and their underlying shell structure was also discussed.
↳ nucl-exnucl-thPRC(2020)·19 citations
16
Nuclear effects on jet substructure observables at the LHC
Paul Caucal🇫🇷 · Edmond Iancu🇫🇷 · Gregory Soyez🇫🇷
Using a pQCD picture for jet evolution in a dense QCD medium, in which medium-induced parton branchings are factorized from vacuum-like emissions, we study two jet substructure observables: the $z_{g}$ and the Soft Drop multiplicity distributions. We compute the respective nuclear modification factors using a Monte-Carlo implementation of the parton showers. Our results are in qualitative agreement with LHC data for Pb+Pb collisions. We identify the physical mechanisms explaining our results: incoherent jet energy loss, semi-hard medium-induced emissions and the bias introduced by the steeply falling jet spectrum.
↳ hep-phnucl-thNPA(2021)·1 citation

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