Nuclear Theory·nucl-th

Monday·July 24, 2017

6 papers—1 primary·5 cross-listed

02
[Submitted on 20 Jul 2017] (cross-list from hep-ph)
A Bayesian analysis of light-front models and the nucleon's charmed sigma term
T. J. Hobbs🇺🇸 · Mary Alberg🇺🇸 · Gerald A. Miller🇺🇸
We present the results of a recent analysis to study the nucleon's charm sigma term, $σ_{c c}$ . We construct a minimal model in terms of light-front variables and constrain the range of possibilities using extant knowledge from deeply inelastic scattering (DIS) and Bayesian parameter estimation, ultimately computing $σ_{c c}$ in an explicitly covariant manner. We find a close correlation between a possible nonperturbative component of the charm structure function, $F_{2, IC}^{c c}$ , and $σ_{c c}$ . Independent of prescription for the covariant relativistic quark-nucleon vertex, we determine $σ_{c c}$ under several different scenarios for the magnitude of intrinsic charm (IC) in DIS, namely $⟨ x ⟩_{c + c} = 0.1%$ , $0.35%$ , and $1%$ , obtaining for these $σ_{c c} = 4 \pm 4$ , $12 \pm 13$ , and $32 \pm 34$ MeV, respectively. These results imply the existence of a reciprocity between the IC parton distribution function (PDF) and $σ_{c c}$ such that new information from either DIS or improved determinations of $σ_{c c}$ could significantly impact constraints to the charm sector of the proton wave function.
Comments:
14 pages, 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1707.06711 [pdf]
PRD(2017)·12 citations
03
[Submitted on 21 Jul 2017] (cross-list from hep-ph)
$K^{*} (892)$ and $ϕ (1020)$ production and their decay into the hadronic medium at the Large Hadron Collider
V. M. Shapoval🇺🇦 · P. Braun-Munzinger🇩🇪 · Yu. M. Sinyukov🇩🇪
The production of the $K^{*} (892)$ strange resonance in Pb+Pb collisions at $s_{N N} = 2.76$ TeV LHC energy is analyzed within the integrated hydrokinetic model (iHKM) at different equations of state of superdense matter. The similar analysis is done also for the RHIC top energy $s_{N N} = 200$ GeV for comparison purposes. A modification of experimental $K^{*} (892)$ -identification is studied for different centralities in view of possible re-scattering of the decay products at the afterburner stage of the fireball evolution. We see quite intensive rescattering of the decay products as well as recombination processes for $K^{*} (892)$ . In addition, the production of the much longer-long-lived $ϕ (1020)$ resonance with hidden strange quark content is investigated.
Comments:
18 pages, 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1707.06753 [pdf]
NPA(2017)·20 citations
04
[Submitted on 21 Jul 2017] (cross-list from physics.comp-ph)
FELIX-2.0: New version of the finite element solver for the time dependent generator coordinate method with the Gaussian overlap approximation
D. Regnier🇫🇷 · N. Dubray🇫🇷 · M. Verrière🇫🇷 · N. Schunck🇺🇸
The time-dependent generator coordinate method (TDGCM) is a powerful method to study the large amplitude collective motion of quantum many-body systems such as atomic nuclei. Under the Gaussian Overlap Approximation (GOA), the TDGCM leads to a local, time-dependent Schrödinger equation in a multi-dimensional collective space. In this paper, we present the version 2.0 of the code FELIX that solves the collective Schrödinger equation in a finite element basis. This new version features: (i) the ability to solve a generalized TDGCM+GOA equation with a metric term in the collective Hamiltonian, (ii) support for new kinds of finite elements and different types of quadrature to compute the discretized Hamiltonian and overlap matrices, (iii) the possibility to leverage the spectral element scheme, (iv) an explicit Krylov approximation of the time propagator for time integration instead of the implicit Crank-Nicolson method implemented in the first version, (v) an entirely redesigned workflow. We benchmark this release on an analytic problem as well as on realistic two-dimensional calculations of the low-energy fission of Pu240 and Fm256. Low to moderate numerical precision calculations are most efficiently performed with simplex elements with a degree 2 polynomial basis. Higher precision calculations should instead use the spectral element method with a degree 4 polynomial basis. We emphasize that in a realistic calculation of fission mass distributions of Pu240, FELIX-2.0 is about 20 times faster than its previous release (within a numerical precision of a few percents).
Subjects:
Computational Physics (physics.comp-ph); Nuclear Theory (nucl-th)
arXiv:
1707.06831 [pdf]
Comput.Phys.Commun.(2018)·41 citations
05
[Submitted on 21 Jul 2017] (cross-list from hep-ph)
New insights into hadron production mechanism from $p_{T}$ spectra in $pp$ collisions at $s = 7$ TeV
Xing-rui Gou🇨🇳 · Feng-lan Shao🇨🇳 · Rui-qin Wang🇨🇳 · Hai-hong Li🇨🇳 · Jun Song🇨🇳
We show that the experimental data of mid-rapidity $p_{T}$ spectra for proton, $Λ$ , $Ξ$ , $Ω^{-}$ , $K(892)^{* 0}$ and $Ξ (1530)^{* 0}$ in minimum-bias $pp$ collisions at $s = 7$ TeV can be systemically explained by the quark combination mechanism of hadronization. The averaged transverse momentum $⟨ p_{T} ⟩$ and spectra ratios such as $Ξ/Λ$ and $Ω/ ϕ$ calculated from quark combination reproduce the data much better than those from traditional string and/or cluster fragmentation. The available data of hadronic $p_{T}$ spectra released by ALICE collaboration in the first three high-multiplicity classes of $pp$ collisions at $s = 7$ TeV are also well explained. We make predictions for other hadrons, and propose two scaling behaviors among decuplet baryons and vector mesons as the effective probe of hadron production mechanism at such high collision energy.
Comments:
11 pages, 10 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1707.06906 [pdf]
PRD(2017)·22 citations
06
[Submitted on 21 Jul 2017] (cross-list from hep-ph)
Fermionic bound states in Minkowski-space: Light-cone singularities and structure
W. de Paula🇧🇷 · T. Frederico🇧🇷 · G. Salmè🇮🇹 · M. Viviani🇮🇹 · R. Pimentel🇧🇷
The Bethe-Salpeter equation for two-body bound system with spin $1/2$ constituent is addressed directly in the Minkowski space. In order to accomplish this aim we use the Nakanishi integral representation of the Bethe-Salpeter amplitude and exploit the formal tool represented by the exact projection onto the null-plane. This formal step allows one i) to deal with end-point singularities one meets and ii) to find stable results, up to strongly relativistic regimes, that settles in strongly bound systems. We apply this technique to obtain the numerical dependence of the binding energies upon the coupling constants and the light-front amplitudes for a fermion-fermion $0^{+}$ state with interaction kernels, in ladder approximation, corresponding to scalar-, pseudoscalar- and vector boson exchanges, respectively. After completing the numerical survey of the previous cases, we extend our approach to a quark-antiquark system in $0^{-}$ state, taking both constituent-fermion and exchanged boson masses, from lattice calculations. Interestingly, the calculated light-front amplitudes for such a mock pion show peculiar signatures of the spin degrees of freedom.
Comments:
22 pages, 7 figures, bst file included
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1707.06946 [pdf]
EPJC(2017)·32 citations

Affiliations

first authorsco-authorsvia INSPIRE

A Bayesian analysis of light-front models and the nucleon's charmed sigma term

K∗(892) and ϕ(1020) production and their decay into the hadronic medium at the Large Hadron Collider

FELIX-2.0: New version of the finite element solver for the time dependent generator coordinate method with the Gaussian overlap approximation

New insights into hadron production mechanism from pT​ spectra in pp collisions at s​=7 TeV

Fermionic bound states in Minkowski-space: Light-cone singularities and structure

Affiliations

$K^{*} (892)$ and $ϕ (1020)$ production and their decay into the hadronic medium at the Large Hadron Collider

New insights into hadron production mechanism from $p_{T}$ spectra in $pp$ collisions at $s = 7$ TeV