Nuclear Theory·nucl-th

Monday·December 19, 2016

19 papers—13 primary·6 cross-listed

14
[Submitted on 14 Dec 2016] (cross-list from hep-ph)
Muon bundles as a sign of strangelets from the Universe
P. Kankiewicz🇵🇱 · M. Rybczynski🇵🇱 · Z. Wlodarczyk🇵🇱 · G. Wilk🇵🇱
Recently the CERN ALICE experiment, in its dedicated cosmic ray run, observed muon bundles of very high multiplicities, thereby confirming similar findings from the LEP era at CERN (in the CosmoLEP project). Originally it was argued that they apparently stem from the primary cosmic rays with a heavy masses. We propose an alternative possibility arguing that muonic bundles of highest multiplicity are produced by strangelets, hypothetical stable lumps of strange quark matter infiltrating our Universe. We also address the possibility of additionally deducing their directionality which could be of astrophysical interest. Significant evidence for anisotropy of arrival directions of the observed high multiplicity muonic bundles is found. Estimated directionality suggests their possible extragalactic provenance.
Comments:
12 pages, 8 figures. Manuscript accepted by The Astrophysical Journal
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1612.04749 [pdf]
ApJ(2017)·20 citations
15
[Submitted on 16 Dec 2016] (cross-list from hep-ph)
Modeling Charmonium- $η$ Decays of $J^{P C} = 1^{--}$ Higher Charmonia
Muhammad Naeem Anwar🇨🇳 · Yu Lu🇨🇳 · Bing-Song Zou🇨🇳
We propose a new model to create a light meson in the heavy quarkonium transition, which is inspired by the Nambu $-$ Jona-Lasinio (NJL) model. Hadronic transitions of $J^{P C} = 1^{--}$ higher charmonia with the emission of an $η$ meson are studied in the framework of the proposed model. The model shows its potential to reproduce the observed decay widths and make predictions for the unobserved channels. We present our predictions for the decay width of $Ψ \to J / ψ η$ and $Ψ \to h_{c} (1 P) η$ , where $Ψ$ are higher $S$ and $D$ wave vector charmonia, which provide useful references to search for higher charmonia and determine their properties in forthcoming experiments. The predicted branching fraction $B (ψ (4415) \to h_{c} (1 P) η) = 4.62 \times 1 0^{- 4}$ is one order of magnitude smaller than the $J / ψ η$ channel. Estimates of partial decay width $Γ (Y \to J / ψ η)$ are given for $Y (4360)$ , $Y (4390)$ and $Y (4660)$ by assuming them as $c c ˉ$ bound states with quantum numbers $3^{3} D_{1}$ , $3^{3} D_{1}$ and $5^{3} S_{1}$ , respectively. Our results are in favor of these assignments for $Y (4360)$ and $Y (4660)$ . The corresponding experimental data for these $Y$ states has large statistical errors which do not provide any constraint on the mixing angle if we introduce $S - D$ mixing. To identify $Y (4390)$ , precise measurements on its hadronic branching fraction are required which are eagerly awaited from BESIII.
Comments:
version published in Phys. Rev. D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1612.05396 [pdf]
PRD(2017)·30 citations
16
[Submitted on 16 Dec 2016] (cross-list from hep-ph)
$η$ - $η^{'}$ Mixing in Large- $N_{c}$ Chiral Perturbation Theory
P. Bickert🇩🇪 · P. Masjuan🇪🇸 · S. Scherer🇩🇪
We present a calculation of the $η$ - $η^{'}$ mixing in the framework of large- $N_{c}$ chiral perturbation theory. A general expression for the $η$ - $η^{'}$ mixing at next-to-next-to-leading order (NNLO) is derived, including higher-derivative terms up to fourth order in the four momentum, kinetic and mass terms. In addition, the axial-vector decay constants of the $η$ - $η^{'}$ system are determined at NNLO. The numerical analysis of the results is performed successively at LO, NLO, and NNLO. We investigate the influence of one-loop corrections, OZI-rule-violating parameters, and $O (N_{c} p^{6})$ contact terms.
Comments:
39 pages, 8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1612.05473 [pdf]
PRD(2017)·37 citations
17
[Submitted on 16 Dec 2016] (cross-list from hep-ph)
Event-by-event picture for the medium-induced jet evolution
Miguel A. Escobedo🇫🇮 · Edmond Iancu🇫🇷
We discuss the evolution of an energetic jet which propagates through a dense quark-gluon plasma and radiates gluons due to its interactions with the medium. Within perturbative QCD, this evolution can be described as a stochastic branching process, that we have managed to solve exactly. We present exact, analytic, results for the gluon spectrum (the average gluon distribution) and for the higher n-point functions, which describe correlations and fluctuations. Using these results, we construct the event-by-event picture of the gluon distribution produced via medium-induced gluon branching. In contrast to what happens in a usual QCD cascade in vacuum, the medium-induced branchings are quasi-democratic, with offspring gluons carrying sizable fractions of the energy of their parent parton. We find large fluctuations in the energy loss and in the multiplicity of soft gluons. The multiplicity distribution is predicted to exhibit KNO (Koba-Nielsen-Olesen) scaling. These predictions can be tested in Pb+Pb collisions at the LHC, via event-by-event measurements of the di-jet asymmetry. Based on JHEP 1605 (2016) 008 and arXiv:1609.06104
Comments:
4 pages, no figures, Hard Probes 2016 proceedings. Based on JHEP 1605 (2016) 008 and arXiv:1609.06104
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1612.05485 [pdf]
EPJ Web Conf.(2017)·0 citations
18
[Submitted on 16 Dec 2016] (cross-list from hep-ph)
Triple parton scatterings in high-energy proton-proton collisions
David d'Enterria🇨🇭 · Alexander M. Snigirev🇷🇺
A generic expression to compute triple parton scattering (TPS) cross sections in high-energy proton-proton (pp) collisions is presented as a function of the corresponding single-parton cross sections and the transverse parton distribution in the proton encoded in an effective parameter $σ_{eff, TPS}$ . The value of $σ_{eff, TPS}$ is closely related to the similar effective cross section that characterizes double-parton scatterings, and amounts to $σ_{eff, TPS} = 12.5 \pm 4.5$ mb. Estimates for triple charm ( $c c$ ) and bottom ( $b b$ ) production in pp collisions at LHC and FCC energies are presented based on next-to-next-to-leading order perturbative calculations for single $c c, b b$ cross sections. At $s \approx$ 100 TeV, about 15% of the pp collisions produce three $c c$ pairs from three different parton-parton scatterings.
Comments:
4 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1612.05582 [pdf]
PRL(2017)·78 citations
19
[Submitted on 16 Dec 2016] (cross-list from nucl-ex)
Studies of three-particle correlations and reaction-plane correlators from STAR
Prithwish Tribedy (for the STAR Collaboration)🇺🇸
We present STAR measurements of various harmonics of three-particle correlations in $s_{N N} = 200$ GeV Au+Au collisions at RHIC. The quantity $⟨ cos (m ϕ_{1} + n ϕ_{2} - (m + n) ϕ_{3})⟩$ is measured for inclusive charged particles for different harmonics $m$ and $n$ as a function of collision centrality, transverse momentum $p_{T}$ and relative pseudorapidity $Δ η$ . These observables provide detailed information on global event properties like correlations between event planes of different harmonics and are particularly sensitive to the expansion dynamics of the matter produced in the collisions. We compare our measurements to different viscous hydrodynamic models. We argue that these measurements probe the three-dimensional structure of the initial state and provide unique ways to constrain the transport parameters involved in hydrodynamic modeling of heavy-ion collisions.
Comments:
6 pages, 3 figures, proceedings of the ISMD 2016 conference, August 29 - September 2, 2016, Jeju island, South Korea, submitted to EPJ Web of Conferences
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1612.05593 [pdf]
EPJ Web Conf.(2017)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Muon bundles as a sign of strangelets from the Universe

Modeling Charmonium-η Decays of JPC=1−− Higher Charmonia

η-η′ Mixing in Large-Nc​ Chiral Perturbation Theory

Event-by-event picture for the medium-induced jet evolution

Triple parton scatterings in high-energy proton-proton collisions

Studies of three-particle correlations and reaction-plane correlators from STAR

Affiliations

Modeling Charmonium- $η$ Decays of $J^{P C} = 1^{--}$ Higher Charmonia

$η$ - $η^{'}$ Mixing in Large- $N_{c}$ Chiral Perturbation Theory