Nuclear Theory·nucl-th

Tuesday·May 7, 2019

13 papers—6 primary·7 cross-listed

01
[Submitted on 3 May 2019]
The Giant Pairing Vibration in Heavy Nuclei: Present Status and Future Studies
M. Assié🇫🇷 · C. H. Dasso🇪🇸 · R. J. Liotta🇸🇪 · A.O. Macchiavelli🇺🇸 · A. Vitturi🇮🇹
The Giant Pairing Vibration, a two-nucleon collective mode originating from the second shell above the Fermi surface, has long been predicted and expected to be strongly populated in two-nucleon transfer reactions with cross sections similar to those of the normal Pairing Vibration. Recent experiments have provided evidence for this mode in $^{14, 15}$ C but, despite sensitive studies, it has not been definitively identified either in Sn or Pb nuclei where pairing correlations are known to play a crucial role near their ground states. In this paper we review the basic theoretical concepts of this "elusive" state and the status of experimental searches in heavy nuclei. We discuss the hindrance effects due to Q-value mismatch and the use of weakly-bound projectiles as a way to overcome the limitations of the (p,t) and (t,p) reactions. We also discuss the role of the continuum and conclude with some possible future developments.
Comments:
Contribution to the special issue of EPJA on the topic "Giant, Pygmy, Pairing Resonances and related topics" dedicated to honor the memory of Pier Francesco Bortignon
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1905.01339 [pdf]
1 citation
02
[Submitted on 6 May 2019]
Production of a 4He_Lambda hypernucleus in the 4He(pi, K) reactions reexamined
Toru Harada🇯🇵 · Yoshiharu Hirabayashi🇯🇵
We investigate theoretically production cross sections of the $J^{π} =$ 0 $^{+}$ ground state of a $_{Λ}^{4}$ He hypernucleus in the $^{4}$ He( $π$ ,~ $K$ ) reaction with a distorted-wave impulse approximation using the optimal Fermi-averaged $π N \to K Λ$ $t$ matrix. We demonstrate the sensitivity of the production cross sections to the $Λ$ wavefunctions obtained from $3 N$ - $Λ$ potentials and to meson distorted waves in eikonal distortions. It is shown that the calculated laboratory cross sections of the 0 $^{+}$ ground state in $_{Λ}^{4}$ He amount to $d σ / d Ω_{lab} ≃$ 11 $μ$ b/sr at $p_{π} =$ 1.05 GeV/ $c$ in the $K$ forward direction because of an advantage of the use of the s-shell target nucleus such as $^{4}$ He. The importance of the recoil effects and the energy dependence of the $π N \to K Λ$ cross sections is also discussed.
Comments:
26 page, 8 figures, 4 Tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1905.01809 [pdf]
PRC(2019)·6 citations
03
[Submitted on 6 May 2019]
Integer and half-integer channel spins for elastic scattering cross sections
A. S. Tkachenko · R. Ya. Kezerashvili · N. A. Burkova · S. B. Dubovichenko
We present the analytical expressions for the differential cross sections and independent partial amplitudes for elastic scattering of nuclear particles for channels with a spin value of 1/2, 1, 3/2, 2 and 5/2. The independent partial amplitudes are presented for arbitrary orbital angular momentum $l$ and taking into account spin-orbit splitting. The analytical expressions allow one to carry out full phase shift analyses using experimental data for differential cross sections for processes with channel spins 1/2, 1, 3/2, 2 and 5/2.
Comments:
33 pages
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1905.01819 [pdf]
NPA(2019)·1 citation
04
[Submitted on 6 May 2019]
Effective lambda-proton and lambda-neutron potentials from subthreshold inverse scattering
Emile Meoto🇿🇦 · Mantile Lekala🇿🇦
Potentials are constructed for the lambda-nucleon interaction in the $^{1} S_{0}$ and $^{3} S_{1}$ channels. These potentials are recovered from scattering phases below the inelastic threshold through Gel'fand-Levitan-Marchenko theory. Experimental data with good statistics is not available for lambda-nucleon scattering. This leaves theoretical scattering phases as the only option through which the rigorous theory of quantum inverse scattering can be used in probing the lambda-nucleon force. Using rational-function interpolations on the theoretical scattering data, the kernels of the Gel'fand-Levitan-Marchenko integral equation become degenerate, resulting in a closed-form solution. The new potentials restored, which are shown to be unique through the Levinson theorem, bear the expected features of short-range repulsion and intermediate-range attraction. Charge symmetry breaking, which is perceptible in the scattering phases, is preserved in the new potentials. The lambda-nucleon force in the $^{1} S_{0}$ channel is observed to be stronger than in the $^{3} S_{1}$ channel, as expected. In addition, the potentials bear certain distinctive features whose effects on hypernuclear systems can be explored through Schrödinger calculations.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1905.01844 [pdf]
J.Phys.Comm.(2019)·5 citations
05
[Submitted on 6 May 2019]
First principles electromagnetic responses in medium-mass nuclei
Johannes Simonis · Sonia Bacca · Gaute Hagen
We review the recent progress made in the computation of electromagnetic response functions in light and medium-mass nuclei using coupled-cluster theory. We show how a many-body formulation of the Lorentz integral transform method allows to calculate the photoabsorption cross sections of $^{16, 22}$ O and $^{40}$ Ca. Then, we discuss electromagnetic sum rules, with particular emphasis on the electric dipole polarizability, $α_{D}$ . By including triples corrections in coupled-cluster theory, we revisit $^{48}$ Ca, for which, beside the electric dipole polarizability, we had previously investigated the neutron and proton radii, as well as the size of the neutron-skin thickness [1]. We show that correlations among these observables still hold, albeit a better agreement with experiment is obtained for $α_{D}$ and the prediction of a small neutron-skin thickness is further corroborated.
Comments:
13 pages, 7 figures, contribution to the special issue of EPJA on the topic "Giant, Pygmy, Pairing Resonances and related topics" dedicated to the memory of Pier Francesco Bortignon
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1905.02055 [pdf]
EPJA(2019)·33 citations
06
[Submitted on 6 May 2019]
Towards baryon-baryon scattering in manifestly Lorentz-invariant formulation of SU(3) baryon chiral perturbation theory
V. Baru🇩🇪 · E. Epelbaum🇩🇪 · J. Gegelia🇩🇪 · X.-L. Ren🇩🇪
We study baryon-baryon scattering by applying time-ordered perturbation theory to the manifestly Lorentz-invariant formulation of SU(3) baryon chiral perturbation theory. We derive the corresponding diagrammatic rules paying special attention to complications caused by momentum-dependent interactions and propagators of particles with non-zero spin. We define the effective potential as a sum of two-baryon irreducible contributions of time-ordered diagrams and derive a system of integral equations for the scattering amplitude, which provides a coupled-channel generalization of the Kadyshevsky equation. The obtained leading-order baryon-baryon potentials are perturbatively renormalizable, and the corresponding integral equations have unique solutions in all partial waves. We discuss the issue of additional finite subtractions required to improve the ultraviolet convergence of (finite) loop integrals on the example of nucleon-nucleon scattering in the $^{3} P_{0}$ partial wave. Assuming that corrections beyond leading order can be treated perturbatively, we obtain a fully renormalizable formalism which can be employed to study baryon-baryon scattering.
Comments:
13 pages, 4 figures, final version published in Phys. Lett. B
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1905.02116 [pdf]
PLB(2019)·29 citations
07
[Submitted on 4 May 2019] (cross-list from nucl-ex)
$^{21}$ Ne level structure in the resonance $^{17}$ O+ $α$ elastic scattering
A. K. Nurmukhanbetova · V. Z. Goldberg · D. K. Nauruzbayev · M. S. Golovkov · A. Volya
The first study of resonances in $^{17}$ O+ $α$ elastic scattering was carried out using the Thick Target Inverse Kinematics (TTIK) method. The data were analyzed in the framework of an $R$ -matrix approach. Many $α$ -cluster states were found in the $^{21}$ Ne excitation region of the 9-13 MeV excitation energy including the first observation of a broad $l$ =0 state in an odd-even nucleus, which is likely the analog of the broad 0 $^{+}$ at 8 MeV in $^{20}$ Ne. The observed structure in $^{21}$ Ne appeared to be strikingly similar to that in $^{20}$ Ne populated in the resonance $^{16}$ O+ $α$ scattering. The results are also useful for refinement of data on an $^{17}$ O( $α$ , $n$ ) reaction important for astrophysics.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1905.01461 [pdf]
PRC(2019)·10 citations
08
[Submitted on 6 May 2019] (cross-list from hep-ph)
Estimating the variation of neutron star observables by symmetric dense nuclear matter properties
Péter Pósfay🇭🇺 · Gergely Gábor Barnaföldi🇭🇺 · Antal Jakovác🇭🇺
Recent multi-channel astrophysics observations and the soon-to-be published new measured electromagnetic and gravitation data provide information on the inner structure of the compact stars. These macroscopic observations can significantly increase our knowledge on the neutron star enteriors, providing constraints on the microscopic physical properties. On the other hand, due to the masquarade problem, there are still uncertainties on the various nuclear-matter models and their parameters as well. Calculating the properties of the dense nuclear matter, effective field theories are the most widely-used tools. However the values of the microscopical parameters need to be set consistently to the nuclear and astrophysical measurements. In this work we investigate how uncertainties are induced by the variation of the microscopical parameters. We use a symmetric nuclear matter in an extended $σ$ - $ω$ model. We calculate the dense matter equation of state and give the mass-radius diagram. We present that the Landau mass and compressibility modulus of the nuclear matter have definite linear relation to the maximum mass of a Schwarzschild neutron star.
Comments:
14 pages, 5 figures 2 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1905.01872 [pdf]
Universe(2019)·7 citations
09
[Submitted on 6 May 2019] (cross-list from hep-ph)
Operator Relations for Gravitational Form Factors
Kazuhiro Tanaka (Juntendo Univ.)🇯🇵
The form factors for the hadron matrix element of the QCD energy-momentum tensor not only describe the coupling of the hadron with a graviton as the ``gravitational form factors'', but also serve as unique quantities for describing the shape inside the hadron reflecting dynamics of quarks and gluons, such as the internal shear forces acting on the quarks/gluons and their pressure distributions. We consider the gravitational form factors for a hadron, in particular, for a (pseudo)scalar hadron and for the nucleon. We derive and clarify the relations satisfied by the gravitational form factors as direct consequences of the symmetries and the equations of motion in QCD, and connections to the generalized parton distributions. Our results reveal that the gravitational form factors are related to the higher-twist quark-gluon correlation effects inside the hadrons and also to QCD trace anomaly.
Comments:
4 pages. To appear in the proceedings of 8th International Conference on Quarks and Nuclear Physics (QNP2018), November 13-17, 2018, Tsukuba, Japan
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1905.01934 [pdf]
JPS Conf.Proc.(2019)·1 citation
10
[Submitted on 6 May 2019] (cross-list from hep-ph)
Unified Analyses of Multiplicity Distributions and Bose-Einstein Correlations at the LHC using Double-Stochastic Distributions
Takuya Mizoguchi🇯🇵 · Minoru Biyajima🇯🇵
We analyze data on multiplicity distributions (MD) at Large Hadron Collider (LHC) energies using a double-negative binomial distribution (D-NBD) and double-generalized Glauber-Lachs formula (D-GGL). Moreover, we investigate the Bose-Einstein correlation (BEC) formulas based on these distributions and analyze the BEC data using the parameters obtained by analysis of MDs. From these analyses it can be inferred that the D-GGL formula performs as effectively as the D-NBD. Moreover, our results show that the parameters estimated in MD are related to those contained in the BEC formula.
Comments:
8th International Conference on Quarks and Nuclear Physics, To be appeared in JPS Conf. Proc. (2019)
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1905.02042 [pdf]
JPS Conf.Proc.(2019)·5 citations
11
[Submitted on 6 May 2019] (cross-list from nucl-ex)
First observation of the directed flow of $D^{0}$ and $D^{0}$ in Au+Au collisions at $s_{NN}$ = 200~GeV
STAR Collaboration: J. Adam🇺🇸 · L. Adamczyk🇵🇱 · J. R. Adams🇺🇸 · J. K. Adkins🇺🇸 · G. Agakishiev🇷🇺 · M. M. Aggarwal🇮🇳 · Z. Ahammed🇮🇳 · I. Alekseev🇷🇺 · D. M. Anderson🇺🇸 · R. Aoyama🇯🇵 · A. Aparin🇷🇺 · D. Arkhipkin🇺🇸 and 339 other authors
We report the first measurement of rapidity-odd directed flow ( $v_{1}$ ) for $D^{0}$ and $D^{0}$ mesons at mid-rapidity ( $∣ y ∣ < 0.8$ ) in Au+Au collisions at $s_{NN}$ = 200\,GeV using the STAR detector at the Relativistic Heavy Ion Collider. In 10--80\% Au+Au collisions, the slope of the $v_{1}$ rapidity dependence ( $d v_{1} / d y$ ), averaged over $D^{0}$ and $D^{0}$ mesons, is -0.080 $\pm$ 0.017 (stat.) $\pm$ 0.016 (syst.) for transverse momentum $p_{T}$ above 1.5~GeV/ $c$ . The absolute value of $D^{0}$ -meson $d v_{1} / d y$ is about 25 times larger than that for charged kaons, with 3.4 $σ$ significance. These data give a unique insight into the initial tilt of the produced matter, and offer constraints on the geometric and transport parameters of the hot QCD medium created in relativistic heavy-ion collisions.
Comments:
Submitted to Phys. Rev. Lett
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1905.02052 [pdf]
PRL(2019)·140 citations
12
[Submitted on 6 May 2019] (cross-list from hep-lat)
Magnetized baryons and the QCD phase diagram: NJL model meets the lattice
Gergely Endrődi🇩🇪 · Gergely Markó🇭🇺
We determine the baryon spectrum of 1 + 1 + 1-flavor QCD in the presence of strong background magnetic fields using lattice simulations at physical quark masses for the first time. Our results show a splitting within multiplets according to the electric charge of the baryons and reveal, in particular, a reduction of the nucleon masses for strong magnetic fields. This first-principles input is used to define constituent quark masses and is employed to set the free parameters of the Polyakov loop-extended Nambu-Jona-Lasinio (PNJL) model in a magnetic field-dependent manner. The so constructed model is shown to exhibit inverse magnetic catalysis at high temperatures and a reduction of the transition temperature as the magnetic field grows - in line with non-perturbative lattice results. This is contrary to the naive variant of this model, which gives incorrect results for this fundamental phase diagram. Our findings demonstrate that the magnetic field dependence of the PNJL model can be reconciled with the lattice findings in a systematic way, employing solely zero-temperature first-principles input.
Comments:
14 pages, 7 figures, updatet some figures, included new references and a table of key results
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1905.02103 [pdf]
JHEP(2019)·70 citations
13
[Submitted on 6 May 2019] (cross-list from nucl-ex)
Comment on "Searching for flavor dependence in nuclear quark behavior"
O. Hen🇺🇸 · F. Hauenstein🇺🇸 · D.W. Higinbotham🇺🇸 · G.A. Miller🇺🇸 · E. Piasetzky🇮🇱 · A. Schmidt🇺🇸 · E.P. Segarra🇺🇸 · M. Strikman🇺🇸 · L.B. Weinstein🇺🇸
Weinstein, et. al [1] [PRL 106, 052301 (2011)] and Hen, et. al [2] [PRC 85, 047301 (2012)] observed a correlation between the EMC effect and the amount of short range correlated (SRC) pairs in nuclei which implies that quark distributions are different in SRC pairs as compared with free nucleons. Schmookler, et. al [3] [Nature 566, 354 (2019)] bolstered this by showing that the EMC data can be explained by a universal modification of the structure of nucleons in neutron-proton SRC pairs and presented the first data-driven extraction of this universal modification function (UMF). Arrington and Fomin [4] [arxiv 1903.12535] attempt to gain insight into the correlation between the EMC effect and SRCs by distinguishing between correlated nucleon pairs at high-virtuality (HV) vs. high local-density (LD). However, there is an inconsistency in their derivations of the UMFs, FLD univ and FHV , causing a non-physical difference between them for asymmetric nuclei. In addition, the univ combinatorial scaling they used to extract high-LD np, pp and nn pairs from measured HV np pairs is contradicted by realistic ab-initio Quantum Monte-Carlo (QMC) calculations.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1905.02172 [pdf]
7 citations

Affiliations

first authorsco-authorsvia INSPIRE