Nuclear Theory·nucl-th

Tuesday·September 18, 2018

15 papers—11 primary·4 cross-listed

12
[Submitted on 14 Sept 2018] (cross-list from hep-ph)
Intriguing feature of multiplicity distributions
M. Rybczyński🇵🇱 · G. Wilk🇵🇱 · Z. Włodarczyk🇵🇱
Multiplicity distributions, P(N), provide valuable information on the mechanism of the production process. We argue that the observed P(N) contain more information (located in the small N region) than expected and used so far. We demonstrate that it can be retrieved by analysing specific combinations of the experimentally measured values of P(N) which we call {it modified combinants, Cj, and which show distinct oscillatory behavior, not observed in the usual phenomenological forms of the P(N) used to fit data. We discuss the possible sources of these oscillations and their impact on our understanding of the multiparticle production mechanism.
Comments:
Invited talk presented at XLVIII International Symposium on Multiparticle Dynamics (ISMD2018), 3 to 7 September 2018, Singapore; 10 pages, 6 figures. To be published in EPJ Web of Conferences
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1809.05362 [pdf]
EPJ Web Conf.(2019)·3 citations
13
[Submitted on 16 Sept 2018] (cross-list from nucl-ex)
Shape Coexistence and Mixing of Low-Lying $0^{+}$ States in $^{96}$ Sr
S. Cruz🇨🇦 · P.C. Bender🇨🇦 · R. Krücken🇨🇦 · K. Wimmer🇯🇵 · F. Ames🇨🇦 · C. Andreoiu🇨🇦 · R.A.E. Austin🇨🇦 · C.S. Bancroft🇺🇸 · R. Braid🇺🇸 · T. Bruhn🇨🇦 · W.N. Catford🇬🇧 · A. Cheeseman🇨🇦 and 23 other authors
The low energy excited $0_{2, 3}^{+}$ states in $^{96}$ Sr are amongst the most prominent examples of shape coexistence across the nuclear landscape. In this work, the neutron $[2 s_{1/2}]^{2}$ content of the $0_{1, 2, 3}^{+}$ states in $^{96}$ Sr was determined by means of the d( $^{95}$ Sr,p) transfer reaction at the TRIUMF-ISAC2 facility using the SHARC and TIGRESS arrays. Spectroscopic factors of 0.19(3) and 0.22(3) were extracted for the $^{96}$ Sr ground and 1229~keV $0^{+}$ states, respectively, by fitting the experimental angular distributions to DWBA reaction model calculations. A detailed analysis of the $γ$ -decay of the isomeric $0_{3}^{+}$ state was used to determine a spectroscopic factor of 0.33(13). The experimental results are compared to shell model calculations, which predict negligible spectroscopic strength for the excited $0^{+}$ states in $^{96}$ Sr. The strengths of the excited $0_{2, 3}^{+}$ states were also analyzed within a two-level mixing model and are consistent with a mixing strength of $a^{2}$ =0.40(14) and a difference in intrinsic deformations of $∣Δ β ∣ = 0.31 (3)$ . These results suggest coexistence of three different configurations in $^{96}$ Sr and strong shape mixing of the two excited $0^{+}$ states.
Comments:
Phys Lett B accepted
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1809.05899 [pdf]
PLB(2018)·23 citations
14
[Submitted on 17 Sept 2018] (cross-list from hep-ph)
Hidden-Bottom Pentaquarks
Gang Yang🇨🇳 · Jialun Ping🇨🇳 · Jorge Segovia🇪🇸
The LHCb Collaboration has recently reported strong evidences of the existence of pentaquark states in the hidden-charm baryon sector, the so-called $P_{c} (4380)^{+}$ and $P_{c} (4450)^{+}$ signals. Five-quark bound states in the hidden-charm sector were explored by us using, for the quark-quark interaction, a chiral quark model which successfully explains meson and baryon phenomenology, from the light to the heavy quark sector. We extend herein such study but to the hidden-bottom pentaquark sector, analyzing possible bound-states with spin-parity quantum numbers $J^{P} = \frac{1}{2}^{\pm}$ , $\frac{3}{2}^{\pm}$ and $\frac{5}{2}^{\pm}$ , and in the $\frac{1}{2}$ and $\frac{3}{2}$ isospin sectors. We do not find positive parity hidden-bottom pentaquark states; however, several candidates with negative parity are found with dominant baryon-meson structures $Σ_{b}^{(*)} B ˉ^{(*)}$ . The calculated distances among any pair of quarks within the bound-state reflect that molecular-type bound-states are favored when only color-singlet configurations are considered in the coupled-channels calculation whereas compact pentaquarks, which are also deeply bound, can be found when hidden-color configurations are added. Finally, our findings resemble the ones found in the hidden-charm sector but, as expected, we find in the hidden-bottom sector larger binding energies and bigger contributions of the hidden-color configurations.
Comments:
11 pages, 9 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1809.06193 [pdf]
PRD(2019)·50 citations
15
[Submitted on 17 Sept 2018] (cross-list from hep-ph)
Anisotropic escape mechanism and elliptic flow of bottomonia
Partha Pratim Bhaduri🇮🇳 · Nicolas Borghini🇩🇪 · Amaresh Jaiswal🇮🇳 · Michael Strickland🇺🇸
We study the role of anisotropic escape in generating the elliptic flow of bottomonia produced in ultrarelativistic heavy-ion collisions. We implement temperature-dependent decay widths for the various bottomonium states, to calculate their survival probability when traversing through the anisotropic hot medium formed in non-central collisions. We employ the recently developed 3+1d quasiparticle anisotropic hydrodynamic simulation to model the space-time evolution of the quark-gluon plasma. We provide a quantitative prediction for transverse momentum dependence of bottomonium elliptic flow and nuclear modification factor for Pb $+$ Pb collisions in $s_{NN} = 2.76$ TeV at the Large Hadron Collider.
Comments:
7 pages, 5 figures; extensively revised text, significant new results
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1809.06235 [pdf]
PRC(2019)·41 citations

Affiliations

first authorsco-authorsvia INSPIRE

Intriguing feature of multiplicity distributions

Shape Coexistence and Mixing of Low-Lying 0+ States in 96Sr

Hidden-Bottom Pentaquarks

Anisotropic escape mechanism and elliptic flow of bottomonia

Affiliations

Shape Coexistence and Mixing of Low-Lying $0^{+}$ States in $^{96}$ Sr