Nuclear Theory·nucl-th

Tuesday·October 30, 2018

14 papers—8 primary·6 cross-listed

09
S-Matrix approach to Compton scattering at the tree level in a strong magnetic field
Jitendra Pal🇮🇳 · Binoy Krishna Patra🇮🇳
We have studied the Compton scattering ( $γ e^{-} ⟶ γ e^{-}$ ) at the tree level in a homogeneous background of strong magnetic field ( $∣ e B ∣ ≫ m^{2}, m is the mass of electron$ ) through the S-matrix approach. For that purpose, using the Schwinger propagator for the electron, we have first calculated the square of the S-matrix element in the Landau gauge by summing over the final states of electron and photon and averaging over the initial states of the same. In the strong magnetic field, only the lowest Landau level for electron is considered. Finally we have computed the crosssection for Compton scattering as a function of initial photon energy for the different strengths of strong magnetic fields, where we have found that the crosssection in vacuum gets decreased due to the presence of strong magnetic field. However, for a fixed initial photon energy, the crosssection increases linearly with the magnetic field.
↳ hep-phhep-thnucl-th2 citations
10
Mass Measurements of Neutron-Rich Gallium Isotopes Refine Production of Nuclei of the First r-Process Abundance Peak in Neutron Star Merger Calculations
M.P. Reiter · S. Ayet San Andrés · S. Nikas · J. Lippuner · C. Andreoiu · C. Babcock · B.R. Barquest · J. Bollig · T. Brunner · T. Dickel · J. Dilling · I. Dillmann and 24 other authors
We report mass measurements of neutron-rich Ga isotopes $^{80 - 85}$ Ga with TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN). The measurements determine the masses of $^{80 - 83}$ Ga in good agreement with previous measurements. The masses of $^{84}$ Ga and $^{85}$ Ga were measured for the first time. Uncertainties between $25 - 48$ keV were reached. The new mass values reduce the nuclear uncertainties associated with the production of A $\approx$ 84 isotopes by the \emph{r}-process for astrophysical conditions that might be consistent with a binary neutron star (BNS) merger producing a blue kilonova. Our nucleosynthesis simulations confirm that BNS merger may contribute to the first abundance peak under moderate neutron-rich conditions with electron fractions $Y_{e} = 0.35 - 0.38$ .
↳ nucl-exastro-ph.HEnucl-thPRC(2020)·27 citations
11
Features of $ω$ photoproduction off proton target at backward angles : Role of nucleon Reggeon in $u$ -channel with parton contributions
Byung-Geel Yu🇰🇷 · Kook-Jin Kong🇰🇷
Backward photoproduction of $ω$ off a proton target is investigated in a Reggeized model where the $u$ -channel nucleon Reggeon is constructed from the nucleon Born terms in a gauge invariant way. The $t$ -channel meson exchanges are considered as a background. While the $N_{α}$ trajectory of the nucleon Reggeon reproduces the overall shape of NINA data measured at the Daresbury Laboratory in the range of $u$ -channel momentum transfer squared $- 1.7 < u < 0.02$ GeV $^{2}$ and energies at $E_{γ} = 2.8$ , 3.5 and 4.7 GeV, a possibility of parton contributions is searched for through the nucleon isoscalar form factor which is parameterized in terms of parton distributions at the $ω N N$ vertex. Detailed analysis is presented for NINA data to understand the reaction mechanism that could fill up the deep dip from the nucleon Reggeon at momentum squared $u = - 0.15$ GeV $^{2}$ . The angle dependence of differential cross sections at the NINA energies above are reproduced in the overall range of $u$ including the CLAS data at forward angles in addition. The energy dependence of the differential cross section is investigated based on the NINA data and the recent LEPS data. A feature of the present approach that implicates parton contributions via nucleon form factor is illustrated in the total and differential cross sections provided by GRAAL and CB-ELSA Collaborations.
↳ hep-phnucl-thPRD(2019)·7 citations
12
General analysis of polarization effects in coherent pseudoscalar mesons photo-- and electroproduction on deuteron
G. I. Gakh🇺🇦 · A. G. Gakh🇺🇦 · E. Tomasi-Gustafsson🇫🇷
General expressions for the unpolarized differential cross section and for various polarization observables in the coherent pseudoscalar meson photo- and electroproduction on the deuteron target have been obtained in one-photon-exchange approximation. The spin structure of the matrix element is explicitly derived in terms of structure functions. The correspondence with the helicity amplitudes is given. The polarization effects have been investigated for the case of a longitudinally polarized electron beam and vector or tensor polarized deuteron target. The polarization (vector or tensor) of the scattered deuteron for the case of unpolarized or a longitudinally polarized electron beam is also considered. In the case of the photoproduction reaction, we consider linearly, circularly or elliptically polarized photon beam. Numerical estimations have been done for the unpolarized differential cross section and for some polarization observables.
↳ hep-phnucl-thPRC(2019)·2 citations
13
The exact discontinuity of a partial wave along the left-hand cut and the exact $N / D$ method in non-relativistic scattering
J. A. Oller🇪🇸 · D. R. Entem🇪🇸
We first deduce the analytical continuation in the complex planes of the initial and final three-momenta of the Lippmann-Schwinger equation in coupled or uncoupled partial-wave amplitudes. This result allows us to deduce a master equation whose solution is the exact discontinuity of the on-shell partial-wave amplitudes along the left-hand cut. This equation is always a linear non-singular integral equation whose solution is fixed exclusively by the knowledge of the potential, applicable to either regular or singular potentials. The capability of calculating exactly this discontinuity allows one to settle the exact $N / D$ method in two-body non-relativistic scattering for coupled and uncoupled waves. We exemplify this new advance in scattering theory by explicitly checking the agreement between the Lippmann-Schwinger equation with the corresponding solutions of the exact $N / D$ method for some examples that involve regular and singular potentials, either attractive or repulsive.
↳ hep-phcond-mat.quant-gashep-thnucl-th+1Annals Phys.(2019)·32 citations
14
Etaprime and Eta Mesons with Connection to Anomalous Glue
Steven D. Bass🇦🇹 · Pawel Moskal🇵🇱
We review the present understanding of etaprime and eta meson physics and these mesons as a probe of gluon dynamics in low-energy QCD. Recent highlights include the production mechanism of eta and etaprime mesons in proton-nucleon collisions from threshold to high-energy, the etaprime effective mass shift in the nuclear medium, searches for possible eta and etaprime bound states in nuclei as well as precision measurements of eta decays as a probe of light-quark masses. We discuss recent experimental data, theoretical interpretation of the different measurements and the open questions and challenges for future investigation.
↳ hep-phhep-exnucl-exnucl-thRMP(2019)·100 citations

Affiliations

first authorsco-authorsvia INSPIRE

S-Matrix approach to Compton scattering at the tree level in a strong magnetic field

Mass Measurements of Neutron-Rich Gallium Isotopes Refine Production of Nuclei of the First r-Process Abundance Peak in Neutron Star Merger Calculations

Features of ω photoproduction off proton target at backward angles : Role of nucleon Reggeon in u-channel with parton contributions

General analysis of polarization effects in coherent pseudoscalar mesons photo-- and electroproduction on deuteron

The exact discontinuity of a partial wave along the left-hand cut and the exact N/D method in non-relativistic scattering

Etaprime and Eta Mesons with Connection to Anomalous Glue

Affiliations

Features of $ω$ photoproduction off proton target at backward angles : Role of nucleon Reggeon in $u$ -channel with parton contributions

The exact discontinuity of a partial wave along the left-hand cut and the exact $N / D$ method in non-relativistic scattering