Nuclear Theory·nucl-th

Friday·September 28, 2018

11 papers—3 primary·8 cross-listed

01
[Submitted on 26 Sept 2018]
Local chiral interactions and magnetic structure of few-nucleon systems
R. Schiavilla🇺🇸 · A. Baroni🇺🇸 · S. Pastore🇺🇸 · M. Piarulli🇺🇸 · L. Girlanda🇮🇹 · A. Kievsky🇮🇹 · A. Lovato🇮🇹 · L.E. Marcucci🇮🇹 · Steven C. Pieper🇺🇸 · M. Viviani🇮🇹 · R.B. Wiringa🇺🇸
The magnetic form factors of $^{2}$ H, $^{3}$ H, and $^{3}$ He, deuteron photodisintegration cross sections at low energies, and deuteron threshold electrodisintegration cross sections at backward angles in a wide range of momentum transfers, are calculated with the chiral two-nucleon (and three-nucleon) interactions including $Δ$ intermediate states that have recently been constructed in configuration space. The $A$ =3 wave functions are obtained from hyperspherical-harmonics solutions of the Schrödinger equation. The electromagnetic current includes one- and two-body terms, the latter induced by one- and two-pion exchange (OPE and TPE, respectively) mechanisms and contact interactions. The contributions associated with $Δ$ intermediate states are only retained at the OPE level, and are neglected in TPE loop (tree-level) corrections to two-body (three-body) current operators. Expressions for these currents are derived and regularized in configuration space for consistency with the interactions. The low-energy constants that enter the contact few-nucleon systems. The predicted form factors and deuteron electrodisintegration cross section are in excellent agreement with experiment for momentum transfers up to 2--3 fm $^{- 1}$ . However, the experimental values for the deuteron photodisintegration cross section are consistently underestimated by theory, unless use is made of the Siegert form of the electric dipole transition operator. A complete analysis of the results is provided, including the clarification of the origin of the aforementioned discrepancy.
Comments:
24 pages, 13 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1809.10180 [pdf]
PRC(2019)·45 citations
02
[Submitted on 27 Sept 2018]
Electromagnetic-radiation effects on alpha decay
M. Apostol
The effect of the electromagnetic radiation on the spontaneous charge emission from heavy atomic nuclei is estimated in a model which may be relevant for proton emission and alpha-particle decay in laser fields. Arguments are given that the electronic cloud in heavy atoms screens appreciably the electric field acting on the nucleus and the nucleus "sees" rather low fields. In these conditions, it is shown that the electromagnetic radiation brings second-order corrections in the electric field to the disintegration rate, with a slight anisotropy. These corrections give a small enhancement of the disintegration rate. The case of a static electric field is also discussed.
Comments:
15 pages
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1809.10349 [pdf]
J.Math.Theor.Phys.(2018)·0 citations
03
[Submitted on 27 Sept 2018]
Manifestation of important role of nuclear forces in emission of photons in scattering of pions off nuclei
Sergei P. Maydanyuk (1 and 2)🇨🇳 · Peng-Ming Zhang (1)🇨🇳 · Li-Ping Zou (1) ((1) Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China, (2) Institute for Nuclear Research, National Academy of Sciences of Ukraine, Ukraine)🇨🇳
Bremsstrahlung of photons emitted during the scattering of $π^{+}$ -mesons off nuclei is studied for the first time. Role of interactions between $π^{+}$ -mesons and nuclei in the formation of the bremsstrahlung emission is analyzed in details. We discover essential contribution of emitted photons from nuclear part of Johnson-Satchler potential to the full spectrum, in contrast to the optical Woods-Saxon potential. We observe unusual essential influence of the nuclear part of both potentials on the spectrum at high photon energies. This phenomenon opens a new experimental way to study and check non-Coulomb and nuclear interactions between pions and nuclei via measurements of the emitted photons. We provide predictions of the bremsstrahlung spectra for pion scattering off $^{44} Ca$ .
Comments:
14 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1809.10403 [pdf]
PRC(2018)·11 citations
04
[Submitted on 27 Sept 2018] (cross-list from hep-ph)
Three-Body Decay of $Λ_{c}^{*} (2595)$ and $Λ_{c}^{*} (2625)$ with the Inclusion of Direct Two-Pion Coupling
A. J. Arifi🇯🇵 · H. Nagahiro🇯🇵 · A. Hosaka🇯🇵
We investigate the three-body decays of $Λ_{c}^{*} (2595)$ and $Λ_{c}^{*} (2625)$ into $Λ_{c} π π$ by including a direct process going through the two-pion coupling of $Λ_{c}^{*} Λ_{c} π π$ in addition to the sequential processes going through $Σ_{c} (2455)$ and $Σ_{c}^{*} (2520)$ . The strength of the direct coupling is related to that of the Yukawa coupling by the chiral partner structure between $Λ_{c}$ 's and $Σ_{c}$ 's, while the strength of the Yukawa coupling is estimated by the quark model. It is found that the direct process gives a considerable contribution especially in the decay of $Λ_{c}^{*} (2625)$ . A clear indication of the direct process is seen in an asymmetric pattern in the angular correlation between the two pions. We discuss the usefulness of the detailed analysis of the decays for the study of the structure of $Λ_{c}^{*}$ .
Comments:
11 pages, 15 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1809.10290 [pdf]
PRD(2018)·13 citations
05
[Submitted on 27 Sept 2018] (cross-list from hep-th)
The interaction of glueball and heavy-light flavoured meson in holographic QCD
Si-wen Li🇨🇳
We construct the D4/D8 brane configuration in the Witten-Sakai-Sugimoto model by introducing a pair of heavy flavour brane with a heavy-light open string. The multiplets created by the heavy-light string acquire mass due to the finite separation of the heavy and light flavour branes thus they could be identified as the heavy-light meson fields in this model. On the other hand the glueball field is identified as the gravitational fluctuations carried by the close string in the bulk, so this model is able to describe the interaction of glueball and heavy-light meson through the open-close string interaction in gauge-gravity duality. We explicitly derive the effective action for the various glueballs and heavy-light mesons then numerically evaluate the associated coupling constants. Afterwards the decay widths of various glueballs to the lowest heavy-light meson, which is identified as $D^{0}$ meson, are calculated by using our effective action. This work extends the previous investigations of glueball in holographic QCD and it is also a further prediction of glueball-meson interaction.
Comments:
33 pages, 2 figures, 2 tables
Subjects:
High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1809.10379 [pdf]
EPJC(2020)·5 citations
06
[Submitted on 27 Sept 2018] (cross-list from nlin.PS)
Conditional recovery of time-reversal symmetry in many nucleus systems
Yoritaka Iwata · Paul Stevenson
Propagation of non-topological soliton in many-nucleus systems is studied based on time-dependent density functional calculations with focusing on mass and energy dependence. The dispersive property and the nonlinearity of the system, which are inherently included in the nuclear density functional, are essential factors to form a non-topological soliton. On the other hand the soliton propagation is prevented by the charge equilibration dynamics, and the competition possibly appears. In this article, based on the energy-dependence of the two competitive factors, the concept of conditional recovery of time-reversal symmetry is proposed in many nucleus systems. It clarifies a possibility of preserving nuclear medium inside natural or artificial nuclear reactors, under a suitable temperature. From an astrophysical point of view, the existence of the low-temperature solitonic core of compact stars is suggested.
Comments:
Submitted
Subjects:
nlin.PS (nlin.PS); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1809.10461 [pdf]
New J.Phys.(2019)·5 citations
07
[Submitted on 27 Sept 2018] (cross-list from hep-ph)
The fate of quarkonia in heavy-ion collisions at LHC energies: a unified description of the sequential suppression patterns
Pietro Faccioli🇵🇹 · Carlos Lourenco🇨🇭
Measurements made at the LHC have shown that the production of the $J / ψ$ , $ψ$ (2S), $Υ$ (1S) and $Υ$ (2S) quarkonia is suppressed in Pb-Pb collisions, with respect to the extrapolation of the pp production yields. The $ψ$ (2S) and $Υ$ (2S) states are more strongly suppressed than the ground states and the level of the suppression changes with the centrality of the collision. We show that the measured patterns can be reproduced by a simple model, where all quarkonia are treated in a unified way, starting from the recent realisation that, in pp collisions, the probability of quarkonium formation has a universal dependence on the binding-energy of the bound state. The hot-medium suppression effect is parametrized by a penalty factor in the binding energy, identical for all (S- and P-wave) charmonium and bottomonium states, including those that indirectly contribute to the measured results through feed-down decays. This single parameter, computed through a global fit of all available suppression patterns, fully determines the hierarchy of nuclear effects, for all states and centrality bins. The resulting faithful description of the data provides convincing evidence in favour of the conjecture of sequential quarkonium suppression induced by QGP formation.
Comments:
The proton-proton baseline model used as a starting point for the study reported in this paper is described in Eur. Phys. J. C 78 (2018) 118
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1809.10488 [pdf]
EPJC(2018)·9 citations
08
[Submitted on 27 Sept 2018] (cross-list from hep-lat)
Light-Neutrino Exchange and Long-Distance Contributions to $0 ν 2 β$ Decays: An Exploratory Study on $π π \to ee$
Xu Feng🇨🇳 · Lu-Chang Jin🇺🇸 · Xin-Yu Tuo🇨🇳 · Shi-Cheng Xia🇨🇳
We present an exploratory lattice QCD calculation of the neutrinoless double beta decay $π π \to ee$ . Under the mechanism of light-neutrino exchange, the decay amplitude involves significant long-distance contributions. The calculation reported here, with pion masses $m_{π} = 420$ and 140 MeV, demonstrates that the decay amplitude can be computed from first principles using lattice methods. At unphysical and physical pion masses, we obtain that amplitudes are $24%$ and $9%$ smaller than the predication from leading order chiral perturbation theory. Our findings provide the lattice QCD inputs and constraints for effective field theory. A follow-on calculation with fully controlled systematic errors will be possible with adequate computational resources.
Comments:
6 pages, 3 figures. V2: version accepted by PRL; minor changes compared to v1
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1809.10511 [pdf]
PRL(2019)·48 citations
09
[Submitted on 27 Sept 2018] (cross-list from quant-ph)
Identifying resonances with wave-packet dynamics
Alexis Diaz-Torres · Jeffrey A. Tostevin
A new method for the study of resonant behavior - using wave-packet dynamics - is presented, based on the powerful window operator technique. The method is illustrated and quantified by application to the astrophysically-important example of low-energy $^{12}$ C + $^{12}$ C collisions. For this selected, potential model test case, the technique is shown to provide both resonance energies and widths in agreement with alternative methods, such as complex-energy scattering-matrix pole searches and scattering phase-shift analyses. The method has a more general capability to study resonance phenomena across disciplines, that involve particles temporarily trapped by potential pockets.
Subjects:
Quantum Physics (quant-ph); Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
arXiv:
1809.10517 [pdf]
0 citations
10
[Submitted on 26 Sept 2018] (cross-list from physics.ins-det)
A beam-beam monitoring detector for the MPD experiment at NICA
Mauricio Alvarado🇲🇽 · Alejandro Ayala🇲🇽 · Marco Alberto Ayala-Torres🇲🇽 · Wolfgang Bietenholz🇲🇽 · Isabel Dominguez🇲🇽 · Marcos Fontaine🇲🇽 · P. González-Zamora🇲🇽 · Luis Manuel Montaño🇲🇽 · E. Moreno-Barbosa🇲🇽 · Miguel Enrique Patiño Salazar🇲🇽 · L. A. P. Moreno🇲🇽 · P.A. Nieto-Marín🇲🇽 and 6 other authors
The Multi-Purpose Detector (MPD) is to be installed at the Nuclotron Ion Collider fAcility (NICA) of the Joint Institute for Nuclear Research (JINR). Its main goal is to study the phase diagram of the strongly interacting matter produced in heavy-ion collisions. These studies, while providing insight into the physics of heavy-ion collisions, are relevant for improving our understanding of the evolution of the early Universe and the formation of neutron stars. In order to extend the MPD trigger capabilities, we propose to include a high granularity beam-beam monitoring detector (BE-BE) to provide a level-0 trigger signal with an expected time resolution of 30 ps. This new detector will improve the determination of the reaction plane by the MPD experiment, a key measurement for flow studies that provides physics insight into the early stages of the reaction. In this work, we use simulated Au+Au collisions at NICA energies to show the potential of such a detector to determine the event plane resolution, providing further redundancy to the detectors originally considered for this purpose namely, the Fast Forward Detector (FFD) and the Hadron Calorimeter (HCAL). We also show our results for the time resolution studies of two prototype cells carried out at the T10 beam line at the CERN PS complex.
Comments:
16 pages, 12 figures. Updated to published version with added comments and corrections
Subjects:
Instrumentation and Detectors (physics.ins-det); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1809.10553 [pdf]
Nucl.Instrum.Meth.A(2020)·8 citations
11
[Submitted on 27 Sept 2018] (cross-list from quant-ph)
Quantum decay law: Critical times and the Equivalence of approaches
D. F. Ramírez Jiménez🇨🇴 · N. G. Kelkar🇨🇴
Methods based on the use of Green's functions or the Jost functions and the Fock-Krylov method are apparently very different approaches to understand the time evolution of unstable states. We show that the two former methods are equivalent up to some constants and as an outcome find an analytic expression for the energy density of states in the Fock-Krylov amplitude in terms of the coefficients introduced in the Green's functions and the Jost functions methods. This model-independent density is further used to obtain an analytical expression for the survival amplitude and study its behaviour at large times. Using these expressions, we investigate the origin of the oscillatory behaviour of the decay law in the region of the transition from the exponential to the non-exponential at large times. With the objective to understand the failure of nuclear and particle physics experiments in observing the non-exponential decay law predicted by quantum mechanics for large times, we derive analytical formulae for the critical transition time, $t_{c}$ , from the exponential to the inverse power law behaviour at large times. Evaluating $τ_{c} = Γ t_{c}$ for some particle resonances and narrow nuclear states which have been tested experimentally to verify the exponential decay law, we conclude that the large time power law in particle and nuclear decay is hard to find experimentally.
Subjects:
Quantum Physics (quant-ph); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1809.10673 [pdf]
J.Phys.A(2019)·17 citations

Affiliations

first authorsco-authorsvia INSPIRE