Nuclear Theory·nucl-th

Monday·October 3, 2016

8 papers—4 primary·4 cross-listed

01
[Submitted on 30 Sept 2016]
The effect of neutron skin on inclusive prompt photon production in Pb~+~Pb collisions at the LHC
Somnath De🇮🇳
Recent experiments on lead (\textrm{ $P b_{82}^{208}$ }) nuclei have observed the celebrated phenomenon of neutron skin-thickness of low energy nuclear physics. The skin-thickness provides a measure of extension of spatial distribution of neutrons inside the atomic nucleus than protons. We have studied the effect of neutron skin-thickness on inclusive prompt photon production in Pb~+~Pb collisions at the Large Hadron Collider energies. We have calculated the \textquoteleft central-to-peripheral ratio\textquoteright ( $R_{cp}$ ) of prompt photon production with and without accounting for neutron skin effect. The neutron skin causes a characteristic enhancement in the ratio, in particular at forward rapidity, which is distinguishable in our calculation. However a very precise direct photon measurement up to large transverse momenta would be necessary to constrain the feature in experiment.
Comments:
10 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1609.09608 [pdf]
J.Phys.G(2017)·9 citations
02
[Submitted on 30 Sept 2016]
Structural evolution in $A \approx 100$ nuclei within the mapped interacting boson model based on the Gogny energy density functional
K. Nomura · R. Rodríguez-Guzmán · L. M. Robledo
The structure of even-even neutron-rich Ru, Mo, Zr and Sr nuclei in the $A \approx 100$ mass region is studied within the interacting boson model (IBM) with microscopic input from the self-consistent mean-field approximation based on the Gogny-D1M energy density functional. The deformation energy surface in the quadrupole deformation space $(β, γ)$ , computed within the constrained Hartree-Fock-Bogoliubov framework, is mapped onto the expectation value of the appropriately chosen IBM Hamiltonian with configuration mixing in the boson condensate state. The mapped IBM Hamiltonian is used to study the spectroscopic properties of $^{98 - 114}$ Ru, $^{96 - 112}$ Mo, $^{94 - 110}$ Zr and $^{92 - 108}$ Sr. Several cases of $γ$ -soft behavior are predicted in Ru and Mo nuclei while a pronounced coexistence between strongly-prolate and weakly-oblate deformed shapes is found for Zr and Sr nuclei. The method describes well the evolution of experimental yrast and non-yrast states as well as selected $B$ (E2) transition probabilities.
Comments:
20 pages, 23 figures, 1 table; To be published in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1609.09614 [pdf]
PRC(2016)·101 citations
03
[Submitted on 30 Sept 2016]
How to Measure Squeeze Out
R.S. Longacre🇺🇸
Squeeze out happen when the expanding central fireball flows around a large surface flux tube in a central Au-Au collision at RHIC. We model such an effect in a flux tube model. Two particle correlations with respect to the $v_{2}$ axis formed by the soft fireball particles flowing around this large flux tube is a way of measuring the effect.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1609.09848 [pdf]
3 citations
04
[Submitted on 30 Sept 2016]
Reverse engineering nuclear properties from rare earth abundances in the $r$ process
M. R. Mumpower · G. C. McLaughlin · R. Surman · A. W. Steiner
The bulk of the rare earth elements are believed to be synthesized in the rapid neutron capture process or $r$ process of nucleosynthesis. The solar $r$ -process residuals show a small peak in the rare earths around $A \sim 160$ , which is proposed to be formed dynamically during the end phase of the $r$ process by a pileup of material. This abundance feature is of particular importance as it is sensitive to both the nuclear physics inputs and the astrophysical conditions of the main $r$ process. We explore the formation of the rare earth peak from the perspective of an inverse problem, using Monte Carlo studies of nuclear masses to investigate the unknown nuclear properties required to best match rare earth abundance sector of the solar isotopic residuals. When nuclear masses are changed, we recalculate the relevant $β$ -decay properties and neutron capture rates in the rare earth region. The feedback provided by this observational constraint allows for the reverse engineering of nuclear properties far from stability where no experimental information exists. We investigate a range of astrophysical conditions with this method and show how these lead to different predictions in the nuclear properties influential to the formation of the rare earth peak. We conclude that targeted experimental campaigns in this region will help to resolve the type of conditions responsible for the production of the rare earth nuclei, and will provide new insights into the longstanding problem of the astrophysical site(s) of the $r$ process.
Comments:
34 pages, 14 figures
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
1609.09858 [pdf]
J.Phys.G(2017)·46 citations
05
[Submitted on 29 Sept 2016] (cross-list from hep-ph)
Probing gluon saturation with next-to-leading order photon production at central rapidities in proton-nucleus collisions
Sanjin Benic🇯🇵 · Kenji Fukushima🇯🇵 · Oscar Garcia-Montero🇩🇪 · Raju Venugopalan🇺🇸
We compute the cross section for photons emitted from sea quarks in proton-nucleus collisions at collider energies. The computation is performed within the dilute-dense kinematics of the Color Glass Condensate (CGC) effective field theory. Albeit the result obtained is formally at next-to-leading order in the CGC power counting, it provides the dominant contribution for central rapidities. We observe that the inclusive photon cross section is proportional to all-twist Wilson line correlators in the nucleus. These correlators also appear in quark-pair production; unlike the latter, photon production is insensitive to hadronization uncertainties and therefore more sensitive to multi-parton correlations in the gluon saturation regime of QCD. We demonstrate that $k_{⊥}$ and collinear factorized expressions for inclusive photon production are obtained as leading twist approximations to our result. In particular, the collinearly factorized expression is directly sensitive to the nuclear gluon distribution at small $x$ . Other results of interest include the realization of the Low-Burnett-Kroll soft photon theorem in the CGC framework and a comparative study of how the photon amplitude is obtained in Lorenz and light-cone gauges.
Comments:
28 pages, 7 figures, a few points clarified, typos corrected, matches the version accepted for publication
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1609.09424 [pdf]
JHEP(2017)·71 citations
06
[Submitted on 29 Sept 2016] (cross-list from quant-ph)
Two-body wave functions and compositeness from scattering amplitudes. I. General properties with schematic models
Takayasu Sekihara (JAEA, Ibaraki)🇯🇵
For a general two-body bound state in quantum mechanics, both in the stable and decaying cases, we establish a way to extract its two-body wave function in momentum space from the scattering amplitude of the constituent two particles. For this purpose, we first show that the two-body wave function of the bound state corresponds to the residue of the off-shell scattering amplitude at the bound state pole. Then, we examine our scheme to extract the two-body wave function from the scattering amplitude in several schematic models. As a result, the two-body wave functions from the Lippmann--Schwinger equation coincides with that from the Schrödinger equation for an energy-independent interaction. Of special interest is that the two-body wave function from the scattering amplitude is automatically scaled; the norm of the two-body wave function, to which we refer as the compositeness, is unity for an energy-independent interaction, while the compositeness deviates from unity for an energy-dependent interaction, which can be interpreted to implement missing channel contributions. We also discuss general properties of the two-body wave function and compositeness for bound states in the schematic models.
Comments:
18 pages, 14 eps files; version accepted for publication in PRC; Section IID is added to discuss the model dependence of the compositeness
Subjects:
Quantum Physics (quant-ph); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1609.09496 [pdf]
PRC(2017)·43 citations
07
[Submitted on 30 Sept 2016] (cross-list from nucl-ex)
Reactions with a 10Be beam to study the one-neutron halo nucleus 11Be
K.L. Jones
Halo nuclei are excellent examples of few-body systems consisting of a core and weakly-bound halo nucleons. Where there is only one nucleon in the halo, as in 11Be, the many-body problem can be reduced to a two-body problem. The contribution of the 1s1/2 orbital to the ground state configuration in 11Be, characterized by the spectroscopic factor, S, has been extracted from direct reaction data by many groups over the past five decades with discrepant results. An experiment was performed at the Holifield Radioactive Ion Beam Facility using a 10Be primary beam at four different energies with the goal of resolving the discrepancy through a consistent analysis of elastic, inelastic, and transfer channels. Faddeev-type calculations, released after the publication of the experimental results, show that dynamic core excitation in the transfer process can lead to reduced differential cross sections at higher beam energies. This reduction would lead to the extraction of decreasing values of S with increasing beam energy. A 10Be(d,p) measurement at Ed greater than 25 MeV is necessary to investigate the effects of core excitation in the reaction.
Comments:
5 pages, 2 figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1609.09751 [pdf]
EPJ Web Conf.(2016)·0 citations
08
[Submitted on 30 Sept 2016] (cross-list from hep-lat)
Progress on the three-particle quantization condition
Raul A. Briceno🇺🇸 · Maxwell T. Hansen🇩🇪 · Stephen R. Sharpe🇺🇸
We report progress on extending the relativistic model-independent quantization condition for three particles, derived previously by two of us, to a broader class of theories, as well as progress on checking the formalism. In particular, we discuss the extension to include the possibility of 2->3 and 3->2 transitions and the calculation of the finite-volume energy shift of an Efimov-like three-particle bound state. The latter agrees with the results obtained previously using non-relativistic quantum mechanics.
Comments:
7 pages, no figures. Proceedings from the 34th annual International Symposium on Lattice Field Theory, 24-30 July 2016, University of Southampton, UK
Subjects:
High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1609.09805 [pdf]
PoS(2016)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE