Nuclear Theory·nucl-th

Monday·February 4, 2019

9 papers—4 primary·5 cross-listed

01
Spectrum of light- and heavy-baryons
Si-Xue Qin🇨🇳 · Craig D. Roberts🇺🇸 · Sebastian M. Schmidt🇩🇪
A symmetry-preserving truncation of the strong-interaction bound-state equations is used to calculate the spectrum of ground-state $J = 1/ 2^{+}$ , $3/ 2^{+}$ $(q q^{'} q^{''})$ -baryons, where $q, q^{'}, q^{''} \in {u, d, s, c, b}$ , their first positive-parity excitations and parity partners. Using two parameters, a description of the known spectrum of 39 such states is obtained, with a mean-absolute-relative-difference between calculation and experiment of 3.6(2.7)%. From this foundation, the framework is subsequently used to predict the masses of 90 states not yet seen empirically.
nucl-thhep-exhep-lathep-ph+1Few Body Syst.(2019)·123 citations
02
Unified description of pairing and quarteting correlations within the particle-hole-boson approach
V.V. Baran · D.S. Delion
We study the description of single-species and isovector pairing correlations in the framework of the projected-BCS (PBCS) and the Quartet Condensation Model (QCM) from a particle-hole perspective and we introduce the representation of the QCM quartet condensate state in terms of particle-hole excitations with respect to the Hartree-Fock state. We also present a new bosonic approximation for both PBCS and QCM. In each case, the starting point is the reformulation of the pair/quartet condensate state in terms of particle-hole excitations with respect to the Hartree-Fock state. The main simplification of our approach is the assumption that the pair operators corresponding to both particle and hole states obey bosonic commutation relations. This simplifies tremendously the computations and allows for an analytic derivation of the averaged Hamiltonian on the condenstate state as a function of the mixing amplitudes. We study both the pure bosonic approach and the renormalized version, and compare the particle-hole bosonic version to the naive prescription of applying the boson approximation directly to the original condensate state. We compare the fermionic and the renormalized particle-hole bosonic approach in the case of a picket fence model of doubly degenerate states and in a realistic shell model space with an effective interaction for the $N = Z$ nuclei above $^{100}$ Sn.
nucl-thPRC(2019)·6 citations
03
Multiple chiral doublet bands with octupole correlations in reflection-asymmetric triaxial particle rotor model
Y. Y. Wang · S. Q. Zhang · P. W. Zhao · J. Meng
A reflection-asymmetric triaxial particle rotor model (RAT-PRM) with a quasi-proton and a quasi-neutron coupled with a reflection-asymmetric triaxial rotor is developed and applied to investigate the multiple chiral doublet (M $χ$ D) bands candidates with octupole correlations in $^{78}$ Br. The calculated excited energies, energy staggering parameters, and $B (M 1) / B (E 2)$ ratios are in a reasonable agreement with the data of the chiral doublet bands with positive- and negative-parity. The influence of the triaxial deformation $γ$ on the calculated $B (E 1)$ is found to be significant. By changing $γ$ from 16 $^{\circ}$ to 21 $^{\circ}$ , the $B (E 1)$ values will be enhanced and better agreement with the $B (E 1) / B (E 2)$ data is achieved. The chiral geometry based on the angular momenta for the rotor, the valence proton and valence neutron is discussed in details.
nucl-thPLB(2019)·46 citations
04
Evidence for Triangular D'(3h) Symmetry in 13C
R. Bijker🇲🇽 · F. Iachello🇺🇸
We derive the rotation-vibration spectrum of a 3alpha+1 neutron (proton) configuration with triangular D(3h) symmetry by exploiting the properties of the double group D'(3h), and show evidence for this symmetry to occur in the rotation-vibration spectra of 13C. Our results, based on purely symmetry considerations, provide benchmarks for microscopic calculations of the cluster structure of light nuclei.
nucl-thnucl-exPRL(2019)·31 citations
05
Lévy imaging of elastic hadron-hadron scattering: Odderon and inner structure of the proton
T. Csörgő🇭🇺 · R. Pasechnik🇸🇪 · A. Ster🇭🇺
A novel model-independent Lévy imaging method is employed for reconstruction of the elastic $pp$ and $p p ˉ$ scattering amplitudes at low and high energies. The four-momentum transfer $t$ dependent elastic slope $B (t)$ , the nuclear phase $ϕ (t)$ as well as the excitation function of the shadow profile $P (b)$ have been extracted from data at ISR, Tevatron and LHC energies. We found qualitative differences in properties of $B (t)$ and $ϕ (t)$ between $pp$ and for $p p ˉ$ collisions, that indicate an Odderon effect. A proton substructure has also been identified and found to have two different sizes, comparable to that of a dressed quark at the ISR and of a dressed diquark at the LHC energies, respectively.
↳ hep-phhep-exnucl-thphysics.data-anActa Phys.Polon.Supp.(2019)·14 citations
06
Quark-Hadron Crossover with Vortices
Chandrasekhar Chatterjee🇯🇵 · Muneto Nitta.🇯🇵 · Shigehiro Yasui🇯🇵
The quark-hadron crossover conjecture was proposed as a continuity between hadronic matter and quark matter with no phase transition. It is based on matching of symmetry and excitations in both the phases. It connects hyperon matter and color-flavor locked (CFL) phase of color superconductivity in the limit of light strange quark mass. We study generalization of this conjecture in the presence of topological vortices. We propose a picture where hadronic superfluid vortices in hyperon matter could be connected to non-Abelian vortices (color magnetic flux tubes) in the CFL phase during this crossover. We propose that three hadronic superfluid vortices must join together to three non-Abelian vortices with different color fluxes with the total color magnetic fluxes canceled out, where the junction is called a colorful boojum.
↳ hep-phastro-ph.HEnucl-thJPS Conf.Proc.(2019)·13 citations
07
Nucleon and $Δ$ isobar in a strong magnetic field
Ulugbek Yakhshiev🇰🇷 · Hyun-Chul Kim🇰🇷 · Makoto Oka🇯🇵
We investigate the static properties of the nucleon in the presence of strong magnetic fields and discuss the consequent changes of the nucleon structure, based on the Skyrme model. The results show that at large values of the magnetic field ( $\sim 1 0^{17}$ to $1 0^{18} G$ ), which is supposed to appear in heavy-ion collision experiments at RHIC energies, the soliton starts to deviate from the spherically symmetric form and its size starts to change. At extremely large values of the magnetic field ( $\sim 1 0^{19}$ G), which may be found at the LHC experiments, the soliton becomes more compact than in free space. The results also show that in the presence of the external magnetic field, the mass of the nucleon tends to increase in general and the mass degeneracy of the $Δ$ isobars from isospin symmetry will be lifted. We also discuss the changes in the mass difference between the $Δ$ and the nucleon, $Δ m_{Δ N}$ , due to the influence of the external magnetic field. We find that $Δ m_{Δ N}$ increases as the strength of the magnetic field grows.
↳ hep-phhep-exnucl-exnucl-thPRD(2019)·14 citations
08
Exclusive dilepton production in ultraperipheral $P b P b$ collisions at the LHC
C. Azevedo🇧🇷 · V.P. Goncalves🇧🇷 · B.D. Moreira🇧🇷
In this paper we perform a systematic study of the exclusive dilepton production by $γ γ$ interactions in $P b P b$ collisions at the LHC Run 2 energies considering different levels of precision for the treatment of the absorptive corrections and for the nuclear form factor. The rapidity and invariant mass distributions are estimated taking into account the experimental cutoffs and a comparison with the recent ALICE and ATLAS data for the $e^{+} e^{-}$ and $μ^{+} μ^{-}$ production is presented.
↳ hep-phhep-exnucl-thEPJC(2019)·51 citations
09
$s$ -wave scattering lengths for the $^{7}$ Be+p system from an $R$ -matrix analysis
S. N. Paneru (1)🇺🇸 · C. R. Brune (1) · R. Giri (1) · R. J. Livesay (2) · U. Greife (2) · J. C. Blackmon (3) · D. W. Bardayan (4) · K. A. Chipps (5) · B. Davids (6 and 7) · D. S. Connolly (6) · K. Y. Chae (8) · A. E. Champagne (9) and 14 other authors
The astrophysical $S$ -factor for the radiative proton capture reaction on $^{7}$ Be ( $S_{17}$ ) at low energies is affected by the $s$ -wave scattering lengths. We report the measurement of elastic and inelastic scattering cross sections for the $^{7}$ Be+p system in the center-of-mass energy range 0.474 - 2.740 MeV and center-of-mass angular range of 70 $^{\circ}$ - 150 $^{\circ}$ . A radioactive $^{7}$ Be beam produced at Oak Ridge National Laboratory's (ORNL) Holifield Radioactive Ion Beam Facility was accelerated and bombarded a thin polypropylene (CH $_{2}$ ) $_{n}$ target. Scattered ions were detected in the segmented Silicon Detector Array. Using an $R$ -matrix analysis of ORNL and Louvain-la-Neuve cross section data, the $s$ -wave scattering lengths for channel spins 1 and 2 were determined to be 17.34 $_{- 1.33}^{+ 1.11}$ and -3.18 $_{- 0.50}^{+ 0.55}$ fm, respectively. The uncertainty in the $s$ -wave scattering lengths reported in this work is smaller by a factor of 5-8 compared to the previous measurement, which may reduce the overall uncertainty in $S_{17}$ at zero energy. The level structure of $^{8}$ B is discussed based upon the results from this work. Evidence for the existence of 0 $^{+}$ and 2 $^{+}$ levels in $^{8}$ B at 1.9 and 2.21 MeV, respectively, is observed.
↳ nucl-exastro-ph.SRnucl-thPRC(2019)·12 citations

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