Nuclear Theory·nucl-th

Wednesday·November 15, 2017

24 papers—16 primary·8 cross-listed

17
[Submitted on 11 Nov 2017] (cross-list from astro-ph.HE)
Gravitomagnetism and Pulsar Beam Precession near a Kerr Black Hole
Prashant Kocherlakota🇮🇳 · Pankaj S. Joshi🇮🇳 · Sudip Bhattacharyya🇮🇳 · Chandrachur Chakraborty🇮🇳 · Alak Ray🇮🇳 · Sounak Biswas🇮🇳
A rotating black hole causes the spin-axis of a nearby pulsar to precess due to geodetic and gravitomagnetic frame-dragging effects. The aim of our theoretical work here is to explore how this spin-precession can modify the rate at which pulses are received on earth. Towards this end, we obtain the complete evolution of the beam vectors of pulsars moving on equatorial circular orbits in the Kerr spacetime, relative to asymptotic fixed observers. We proceed to establish that such spin-precession effects can significantly modify observed pulse frequencies and, in specific, we find that the observed pulse frequency rises sharply as the orbit shrinks, potentially providing a new way to locate horizons of Kerr black holes, even if observed for a very short time period. We also discuss implications for detections of sub-millisecond pulsars, pulsar nulling, quasi-periodic oscillations, multiply-peaked pulsar Fourier profiles and how Kerr black holes can potentially be distinguished from naked singularities.
Comments:
27 pages, 8 figures, 1 Table; To appear in MNRAS
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1711.04053 [pdf]
MNRAS(2019)·19 citations
18
[Submitted on 12 Nov 2017] (cross-list from hep-ph)
Color superconductivity from the chiral quark-meson model
Armen Sedrakian🇩🇪 · Ralf-Arno Tripolt🇮🇹 · Jochen Wambach🇮🇹
We study the two-flavor color superconductivity of low-temperature quark matter in the vicinity of chiral phase transition in the quark-meson model where the interactions between quarks are generated by pion and sigma exchanges. Starting from the Nambu-Gor'kov propagator in real-time formulation we obtain finite temperature (real axis) Eliashberg-type equations for the quark self-energies (gap functions) in terms of the in-medium spectral function of mesons. Exact numerical solutions of the coupled nonlinear integral equations for the real and imaginary parts of the gap function are obtained in the zero temperature limit using a model input spectral function. We find that these components of the gap display a complicated structure with the real part being strongly suppressed above $2 Δ_{0}$ , where $Δ_{0}$ is its on-shell value. We find $Δ_{0} ≃ 40$ MeV close to the chiral phase transition.
Comments:
v2: minor clarifications, matches published version; v1: 8 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1711.04269 [pdf]
PLB(2018)·8 citations
19
[Submitted on 13 Nov 2017] (cross-list from hep-ph)
Inclusive heavy quark photoproduction in $pp$ , $pP b$ and $P b P b$ collisions at Run 2 LHC energies
V. P. Goncalves🇧🇷 · G. Sampaio dos Santos🇧🇷 · C. R. Sena🇧🇷
In this paper we present a comprehensive analysis of the inclusive heavy quark photoproduction in $pp$ , $pP b$ and $P b P b$ collisions at Run 2 LHC energies using the Color Dipole formalism. The rapidity distributions and total cross sections for the charm and bottom production are estimated considering the more recent phenomenological models for the dipole - proton scattering amplitude, which are based on the Color Glass Condensate formalism and are able to describe the inclusive and exclusive $e p$ HERA data. Moreover, we present, by the first time, the predictions for the transverse momentum distributions of the $D$ and $B$ mesons produced in the photon -- induced interactions.
Comments:
9 pages, 5 figures, 1 table. arXiv admin note: text overlap with arXiv:1710.10070
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1711.04497 [pdf]
NPA(2018)·20 citations
20
[Submitted on 13 Nov 2017] (cross-list from hep-ph)
Heavy quarkonium suppression in a fireball
Nora Brambilla🇩🇪 · Miguel A. Escobedo🇫🇮 · Joan Soto🇪🇸 · Antonio Vairo🇩🇪
We perform a comprehensive study of the time evolution of heavy-quarkonium states in an expanding hot QCD medium by implementing effective field theory techniques in the framework of open quantum systems. The formalism incorporates quarkonium production and its subsequent evolution in the fireball including quarkonium dissociation and recombination. We consider a fireball with a local temperature that is much smaller than the inverse size of the quarkonium and much larger than its binding energy. The calculation is performed at an accuracy that is leading-order in the heavy-quark density expansion and next-to-leading order in the multipole expansion. Within this accuracy, for a smooth variation of the temperature and large times, the evolution equation can be written as a Lindblad equation. We solve the Lindblad equation numerically both for a weakly-coupled quark-gluon plasma and a strongly-coupled medium. As an application, we compute the nuclear modification factor for the $Υ (1 S)$ and $Υ (2 S)$ states. We also consider the case of static quarks, which can be solved analytically. Our study fulfils three essential conditions: it conserves the total number of heavy quarks, it accounts for the non-Abelian nature of QCD and it avoids classical approximations.
Comments:
Figure 8 added and improved bibliography. Journal version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1711.04515 [pdf]
PRD(2018)·183 citations
21
[Submitted on 13 Nov 2017] (cross-list from hep-ph)
Structure of hadron resonances with a nearby zero of the amplitude
Yuki Kamiya🇯🇵 · Tetsuo Hyodo🇯🇵
We discuss the relation between the analytic structure of the scattering amplitude and the origin of an eigenstate represented by a pole of the amplitude.If the eigenstate is not dynamically generated by the interaction in the channel of interest, the residue of the pole vanishes in the zero coupling limit. Based on the topological nature of the phase of the scattering amplitude, we show that the pole must encounter with the Castillejo-Dalitz-Dyson (CDD) zero in this limit. It is concluded that the dynamical component of the eigenstate is small if a CDD zero exists near the eigenstate pole. We show that the line shape of the resonance is distorted from the Breit-Wigner form as an observable consequence of the nearby CDD zero. Finally, studying the positions of poles and CDD zeros of the KbarN-piSigma amplitude, we discuss the origin of the eigenstates in the Lambda(1405) region.
Comments:
7 pages, 3 figures, v2: published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1711.04558 [pdf]
PRD(2018)·11 citations
22
[Submitted on 13 Nov 2017] (cross-list from hep-ph)
Polarization Transfer in Weak Pion Production off the Nucleon
Krzysztof M. Graczyk🇵🇱 · Beata E. Kowal🇵🇱
Polarization transfer (PT) observables in the single pion production induced by the charged current interaction of the neutrino with the nucleon are examined. The polarization components of the final nucleon and the charged lepton are calculated within two models for the pion production. The predictions are made for neutrino energy of the order of 1~GeV as well as for the T2K energy distribution. It is demonstrated that the PT observables, the degree of polarization and the polarization components of outgoing fermions, are sensitive on assumptions about the nonresonant background model. In particular it is shown that the normal components of the polarization of the outgoing nucleon and the lepton are determined by the interference between the resonant (RES) and nonresonant (NB) amplitudes. Moreover the sign of the normal component of the polarization of the charged lepton is fixed by the relative sign between the RES and the NB amplitudes.
Comments:
20 pages, 15 figures: 4 new figures, one new reference and two corrections in references
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1711.04868 [pdf]
PRD(2018)·15 citations
23
[Submitted on 14 Nov 2017] (cross-list from nucl-ex)
The dominance of the $ν (0 d_{5/2})^{2}$ configuration in the $N = 8$ shell in $^{12}$ Be from the breakup reaction on a proton target at intermediate energy
Le Xuan Chung🇻🇳 · Carlos A. Bertulani🇺🇸 · Peter Egelhof🇩🇪 · Stoyanka Ilieva🇩🇪 · Dao T. Khoa🇻🇳 · Oleg A. Kiselev🇩🇪
The momentum distribution of $^{11}$ Be fragments produced by the breakup of $^{12}$ Be interacting with a proton target at 700.5 MeV/ $u$ energy has been measured at GSI Darmstadt. To obtain the structure information on the anomaly of the $N = 8$ neutron shell, the momentum distribution of $^{11}$ Be fragments from the one-neutron knockout $^{12}$ Be(p,pn) reaction, measured in inverse kinematics, has been analysed in the distorted wave impulse approximation (DWIA) based on a quasi-free scattering scenario. The DWIA analysis shows a surprisingly strong contribution of the neutron $0 d_{5/2}$ orbital in $^{12}$ Be to the transverse momentum distribution of the $^{11}$ Be fragments. The single-neutron $0 d_{5/2}$ spectroscopic factor deduced from the present knock-out data is 1.39(10), which is significantly larger than that deduced recently from data of $^{12}$ Be breakup on a carbon target. This result provides a strong experimental evidence for the dominance of the neutron $ν (0 d_{5/2})^{2}$ configuration in the ground state of $^{12}$ Be.
Comments:
Accepted for publication in Physics Letters B
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1711.04926 [pdf]
PLB(2017)·9 citations
24
[Submitted on 14 Nov 2017] (cross-list from hep-ph)
Covariant Extension of the GPD overlap representation at low Fock states
N. Chouika🇫🇷 · C. Mezrag🇺🇸 · H. Moutarde🇫🇷 · J. Rodríguez-Quintero🇪🇸
We present a novel approach to compute Generalized Parton Distributions within the Lightfront Wave Function overlap framework. We show how to systematically extend Generalized Parton Distributions computed within the DGLAP region to the ERBL one, fulfilling at the same time both the polynomiality and positivity conditions. We exemplify our method using pion Lightfront Wave Functions inspired by recent results of non-perturbative continuum techniques and algebraic nucleon Lightfront Wave Functions. We also test the robustness of our algorithm on reggeized phenomenological parameterizations. This approach paves the way to a better understanding of the nucleon structure from non-perturbative techniques and to a unification of Generalized Parton Distributions and Transverse Momentum Dependent Parton Distribution Functions phenomenology through Lightfront Wave Functions.
Comments:
36 pages, 11 figures, matches published version in EPJC
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
arXiv:
1711.05108 [pdf]
EPJC(2017)·53 citations

Affiliations

first authorsco-authorsvia INSPIRE