Nuclear Theory·nucl-th

Friday·September 25, 2015

10 papers—6 primary·4 cross-listed

01
[Submitted on 23 Sept 2015]
Microscopic optical potential for exotic isotopes from chiral effective field theory
J. W. Holt · N. Kaiser · G. A. Miller
We compute the isospin-asymmetry dependence of microscopic optical model potentials from realistic chiral two- and three-body interactions over a range of resolution scales $Λ ≃ 400 - 500$ \,MeV. We show that at moderate projectile energies, $E_{inv} = 110 - 200$ \,MeV, the real isovector part of the optical potential changes sign, a phenomenon referred to as isospin inversion. We also extract the strength and energy dependence of the imaginary isovector optical potential and find no evidence for an analogous phenomenon over the range of energies, $E \leq 200$ \,MeV, considered in the present work. Finally, we compute for the first time the leading corrections to the Lane parametrization for the isospin-asymmetry dependence of the optical potential and observe an enhanced importance at low scattering energies.
Comments:
8 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.07126 [pdf]
PRC(2016)·48 citations
02
[Submitted on 23 Sept 2015]
Charge, neutron, and weak size of the atomic nucleus
G. Hagen · A. Ekström · C. Forssén · G. R. Jansen · W. Nazarewicz · T. Papenbrock · K. A. Wendt · S. Bacca · N. Barnea · B. Carlsson · C. Drischler · K. Hebeler and 5 other authors
What is the size of the atomic nucleus? This deceivably simple question is difficult to answer. While the electric charge distributions in atomic nuclei were measured accurately already half a century ago, our knowledge of the distribution of neutrons is still deficient. In addition to constraining the size of atomic nuclei, the neutron distribution also impacts the number of nuclei that can exist and the size of neutron stars. We present an ab initio calculation of the neutron distribution of the neutron-rich nucleus $^{48}$ Ca. We show that the neutron skin (difference between radii of neutron and proton distributions) is significantly smaller than previously thought. We also make predictions for the electric dipole polarizability and the weak form factor; both quantities are currently targeted by precision measurements. Based on ab initio results for $^{48}$ Ca, we provide a constraint on the size of a neutron star.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1509.07169 [pdf]
Nat.Phys.(2015)·379 citations
03
[Submitted on 24 Sept 2015]
Double scattering production of two $ρ^{0}$ mesons in UPC
Mariola Kłusek-Gawenda🇵🇱 · Antoni Szczurek🇵🇱
We review our recent results for double-scattering mechanism in the exclusive $AA \to AA ρ^{0} ρ^{0}$ reaction in ultrarelativistic ultraperipheral heavy ion collisions. The cross section for single and double- $ρ^{0}$ production is calculated in the impact parameter space equivalent photon approximation. We compare the results of our calculation with the STAR and ALICE Collaboration results on one $ρ^{0} (770)$ meson and four-charged-pion production.
Comments:
6 pages, 5 figures, presented at the 16th conference on Elastic and Diffractive Scattering, EDS Blois 2015, Borgo, Corsica, France, June/July 2015
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1509.07286 [pdf]
Acta Phys.Polon.Supp.(2015)·0 citations
04
[Submitted on 24 Sept 2015]
Hybrid method to resolve the neutrino mass hierarchy by supernova (anti)neutrino induced reactions
D. Vale🇭🇷 · T. Rauscher🇬🇧 · N. Paar🇭🇷
We introduce a hybrid method to determine the neutrino mass hierarchy by simultaneous measurements of responses of at least two detectors to antineutrino and neutrino fluxes from accretion and cooling phases of core-collapse supernovae. The (anti)neutrino-nucleus cross sections for $^{56}$ Fe and $^{208}$ Pb are calculated in the framework of the relativistic nuclear energy density functional and weak interaction Hamiltonian, while the cross sections for inelastic scattering on free protons $p (ν ˉ_{e}, e^{+}) n$ are obtained using heavy-baryon chiral perturbation theory. The modelling of (anti)neutrino fluxes emitted from a protoneutron star in a core-collapse supernova include collective and Mikheyev-Smirnov-Wolfenstein effects inside the exploding star. The particle emission rates from the elementary decay modes of the daughter nuclei are calculated for normal and inverted neutrino mass hierarchy. It is shown that simultaneous use of (anti)neutrino detectors with different target material allows to determine the neutrino mass hierarchy from the ratios of $ν_{e}$ - and $ν ˉ_{e}$ -induced particle emissions. This hybrid method favors neutrinos from the supernova cooling phase and the implementation of detectors with heavier target nuclei ( $^{208}$ Pb) for the neutrino sector, while for antineutrinos the use of free protons in mineral oil or water is the appropriate choice.
Comments:
22 pages, 7 figures, 3 tables
Subjects:
Nuclear Theory (nucl-th); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex)
arXiv:
1509.07342 [pdf]
JCAP(2016)·12 citations
05
[Submitted on 24 Sept 2015]
Estimating $η / s$ of QCD matter at high baryon densities
Iu. Karpenko🇺🇦 · M. Bleicher🇩🇪 · P. Huovinen🇩🇪 · H. Petersen🇩🇪
We report on the application of a cascade + viscous hydro + cascade model for heavy ion collisions in the RHIC Beam Energy Scan range, $s_{NN} = 6.3 \dots 200$ GeV. By constraining model parameters to reproduce the data we find that the effective(average) value of the shear viscosity over entropy density ratio $η / s$ decreases from 0.2 to 0.08 when collision energy grows from $s_{NN} \approx 7$ to 39 GeV.
Comments:
4 pages, proceedings of the Strangeness in Quark Matter 2015, Dubna, July 6-11, 2015
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1509.07351 [pdf]
J.Phys.Conf.Ser.(2016)·2 citations
06
[Submitted on 24 Sept 2015]
Fluctuations of harmonic and radial flow in heavy ion collisions with principal components
Aleksas Mazeliauskas🇺🇸 · Derek Teaney🇺🇸
We analyze the spectrum of harmonic flow, $v_{n} (p_{T})$ for $n = 0 - 5$ , in event-by-event hydrodynamic simulations of Pb+Pb collisions at the CERN Large Hadron Collider ( $s_{N N} = 2.76 TeV$ ) with principal component analysis (PCA). The PCA procedure finds two dominant contributions to the two-particle correlation function. The leading component is identified with the event plane $v_{n} (p_{T})$ , while the subleading component is responsible for factorization breaking in hydrodynamics. For $v_{0}$ , $v_{1}$ , and $v_{3}$ the subleading flow is a response to the radial excitation of the corresponding eccentricity. By contrast, for $v_{2}$ the subleading flow in \emph{peripheral collisions} is dominated by the nonlinear mixing between the leading elliptic flow and radial flow fluctuations. In the $v_{2}$ case, the sub-sub-leading mode more closely reflects the response to the radial excitation of $ε_{2}$ . A consequence of this picture is that the elliptic flow fluctuations and factorization breaking change rapidly with centrality, and in central collisions (where the leading $v_{2}$ is small and nonlinear effects can be neglected) the subsub-leading mode becomes important. Radial flow fluctuations and nonlinear mixing also play a significant role in the factorization breaking of $v_{4}$ and $v_{5}$ . We construct good geometric predictors for the orientation and magnitudes of the leading and subleading flows based on a linear response to the geometry, and a quadratic mixing between the leading principal components. Finally, we suggest a set of measurements involving three point correlations which can experimentally corroborate the nonlinear mixing of radial and elliptic flow and its important contribution to factorization breaking as a function of centrality.
Comments:
updated references and small corrections, 15 pages 13 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.07492 [pdf]
PRC(2016)·65 citations
07
[Submitted on 24 Sept 2015] (cross-list from hep-ph)
Towards the understanding of jet shapes and cross sections in heavy ion collisions using soft-collinear effective theory
Yang-Ting Chien🇺🇸 · Ivan Vitev🇺🇸
We calculate the jet shape and the jet cross section in heavy ion collisions using soft-collinear effective theory (SCET) and its extension with Glauber gluon interactions in the medium (SCET $_{G}$ ). We use the previously developed framework to systematically resum the jet shape at next-to-leading logarithmic accuracy, and we consistently include the medium modification by incorporating the leading order medium-induced splitting functions. The calculation provides, for the first time, a quantitative understanding of the jet shape modification measurement in lead-lead collisions at $s_{NN} = 2.76$ TeV at the LHC. The inclusive jet suppression is also calculated within the same framework beyond the traditional concept of parton energy loss, and the dependence on the centrality, the jet radius and the jet kinematics is examined. In the end we present predictions for the anticipated jet shape and cross section measurements in lead-lead collisions at $s_{NN} \approx 5.1$ TeV at the LHC.
Comments:
26 pages, 12 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1509.07257 [pdf]
JHEP(2016)·150 citations
08
[Submitted on 24 Sept 2015] (cross-list from hep-ph)
Violations of discrete space-time symmetries in chiral effective field theory
J. de Vries🇩🇪 · Ulf-G. Meißner🇩🇪
We review recent progress in the theoretical description of the violation of discrete space-time symmetries in hadronic and nuclear systems. We focus on parity-violating and time-reversal-conserving interactions which are induced by the Standard Model weak interaction, and on parity- and time-reversal-violating interactions which can be caused by a nonzero QCD theta term or by beyond-the-Standard Model physics. We discuss the origins of such interactions and review the development of the chiral effective field theory extension that includes discrete symmetry violations. We discuss the construction of symmetry-violating chiral Lagrangians and nucleon-nucleon potentials and their applications in few-body systems.
Comments:
Review article commissioned for a special issue of the International Journal of Modern Physics E. v2: Published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1509.07331 [pdf]
IJMPE(2016)·52 citations
09
[Submitted on 24 Sept 2015] (cross-list from hep-ph)
Quarkonium at finite temperature: Towards realistic phenomenology from first principles
Yannis Burnier🇨🇭 · Olaf Kaczmarek🇩🇪 · Alexander Rothkopf🇩🇪
We present the finite temperature spectra of both bottomonium and charmonium, obtained from a consistent lattice QCD based potential picture. Starting point is the complex in-medium potential extracted on full QCD lattices with dynamical u,d and s quarks, generated by the HotQCD collaboration. Using the generalized Gauss law approach, vetted in a previous study on quenched QCD, we fit $Re [V]$ with a single temperature dependent parameter $m_{D}$ , the Debye screening mass, and confirm the up to now tentative values of $Im [V]$ . The obtained analytic expression for the complex potential allows us to compute quarkonium spectral functions by solving an appropriate Schrödinger equation. These spectra exhibit thermal widths, which are free from the resolution artifacts that plague direct reconstructions from Euclidean correlators using Bayesian methods. In the present adiabatic setting, we find clear evidence for sequential melting and derive melting temperatures for the different bound states. Quarkonium is gradually weakened by both screening ( $Re [V]$ ) and scattering ( $Im [V]$ ) effects that in combination lead to a shift of their in-medium spectral features to smaller frequencies, contrary to the mass gain of elementary particles at finite temperature.
Comments:
36 pages, 11 figures (added figures and supplementary discussion, submitted to JHEP)
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1509.07366 [pdf]
JHEP(2015)·137 citations
10
[Submitted on 24 Sept 2015] (cross-list from hep-ph)
Radiative energy loss and radiative p_T-broadening of high-energy partons in QCD matter
Bin Wu🇫🇷
I give a self-contained review on radiative p_T-broadening and radiative energy loss of high-energy partons in QCD matter. The typical p_T^2 of high-energy partons receives a double logarithmic correction due to the recoiling effect of medium-induced gluon radiation. Such a double logarithmic term, averaged over the path length of the partons, can be taken as the radiative correction to the jet quenching parameter qhat and hence contributes to radiative energy loss. This has also been confirmed by detailed calculations of energy loss by radiating two gluons.
Comments:
4 pages, 1 figure, a brief review as a slight extension of talk at Hard Probes 2015
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1509.07483 [pdf]
Nucl.Part.Phys.Proc.(2016)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE