Nuclear Theory·nucl-th

Wednesday·January 3, 2018

14 papers—5 primary·9 cross-listed

01
[Submitted on 30 Dec 2017]
Chiral symmetry breaking in a semi-localized magnetic field
Gaoqing Cao🇨🇳
In this work, I'm going to explore the pattern of chiral symmetry breaking and restoration in a solvable magnetic distribution within Nambu--Jona-Lasinio model. The special semi-localized static magnetic field can roughly simulate the realistic situation in peripheral heavy ion collisions, thus the study is important for the dynamical evolution of quark matter. I find that the magnetic field dependent contribution from discrete spectra usually dominates over that from continuum ones and chiral symmetry breaking is locally catalyzed by both the magnitude and scale of the magnetic field.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1801.00134 [pdf]
PRD(2018)·6 citations
02
[Submitted on 31 Dec 2017]
Hydrodynamic Collectivity in Proton--Proton Collisions at 13 TeV
Wenbin Zhao🇨🇳 · You Zhou🇩🇰 · Hao-jie Xu🇨🇳 · Weitian Deng🇨🇳 · Huichao Song🇨🇳
In this paper, we investigate the hydrodynamic collectivity in proton--proton (pp) collisions at 13 TeV, using iEBE-VISHNU hybrid model with HIJING initial conditions. With properly tuned parameters, our model simulations can remarkably describe all the measured 2-particle correlations, including integrated and differential elliptic flow coefficients for all charged and identified hadrons ( $K_{S}^{0}$ , $Λ$ ). However, our model calculations show positive 4-particle cumulant $c_{2} {4}$ in high multiplicity pp collisions, and can not reproduce the negative $c_{2} {4}$ measured in experiment. Further investigations on the HIJING initial conditions show that the fluctuations of the second order anisotropy coefficient $ε_{2}$ increases with the increase of its mean value, which leads to a similar trend of the flow fluctuations. For a simultaneous description of the 2- and 4- particle cumulants within the hydrodynamic framework, it is required to have significant improvements on initial condition for pp collisions, which is still lacking of knowledge at the moment.
Comments:
7 pages, 6 figures, published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1801.00271 [pdf]
PLB(2018)·96 citations
03
[Submitted on 2 Jan 2018]
Hoyle-analogue state in 13C studied with Antisymmetrized Molecular Dynamics
Y. Chiba · M. Kimura
The cluster states in $^{13} C$ are investigated by antisymmetrized molecular dynamics. By investigating the spectroscopic factors, the cluster configurations of the excited states are discussed. It is found that the $1/ 2_{2}^{+}$ state is dominantly composed of the $^{12} C (0_{2}^{+}) \otimes s_{1/2}$ configuration and can be regarded as a Hoyle analogue state. On the other hand, the p-wave states ( $3/ 2^{-}$ and $1/ 2^{-}$ ) do not have such structure, because of the coupling with other configurations. The isoscalar monopole and dipole transition strengths from the ground to the excited states are also studied. It is shown that the excited $1/ 2^{-}$ states have strong isoscalar monopole transition strengths consistent with the observation. On the other hand, the excited $1/ 2^{+}$ states unexpectedly have weak isoscalar dipole transitions except for the $1/ 2_{1}^{+}$ state. It is discussed that the suppression of the dipole transition is attributed to the property of the dipole operator.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1801.00562 [pdf]
PRC(2020)·22 citations
04
[Submitted on 2 Jan 2018]
Shape coexistence close to $N = 50$ in the neutron-rich isotope $^{80}$ Ge investigated by IBM-2
Dali Zhang · Chengfu Mu
The properties of the low-lying states, especially the relevant shape coexistence in $^{80}$ Ge close to one of most neutron-rich doubly magic nuclei at $N = 50$ and $Z = 28$ have been investigated within the framework of the proton-neutron interacting model (IBM-2). Based on the fact that the relative energy of the $d$ neutron boson is different from proton bosons', the calculated energy levels of low-lying states, $E 2$ transition strengths can reproduce the experimental data very well. Particularly, the first excited state 0 $_{2}^{+}$ is reproduced quite nicely, which is intimately related with the shape coexistence phenomenon. And the $ρ^{2} (E 0, 0_{2}^{+} \to 0_{1}^{+})$ transition strength has been predicted. The experimental data and theoretical results indicate that both collective spherical and $γ$ -soft vibration structures coexist in $^{80}$ Ge. Key words: $^{80}$ Ge, low-lying states, $E 0$ transition strengths, shape coexistence, IBM-2.
Comments:
13 pages, 1 figure, accepted by Chinese Physics C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1801.00579 [pdf]
CPC(2018)·6 citations
05
[Submitted on 2 Jan 2018]
Radiative heavy quark energy loss in an expanding viscous QCD plasma
Sreemoyee Sarkar🇮🇳 · Chandrodoy Chattopadhyay🇮🇳 · Subrata Pal🇮🇳
We study viscous effects on heavy quark radiative energy loss in a dynamically screened medium with boost-invariant longitudinal expansion. We calculate, to first order in opacity, the energy loss by incorporating viscous corrections in the single-particle phase-space distribution function within relativistic dissipative hydrodynamics. We consider the Grad's 14-moment and the Chapman-Enskog-like methods for the nonequilibrium distribution functions. Our numerical results for the charm quark radiative energy loss show that, as compared to static fluid, an expanding ideal (nonviscous) fluid causes a much smaller energy loss. Viscosity in the evolution lead to somewhat enhanced energy loss which is insensitive to the underlying viscous hydrodynamic models used. Further inclusion of viscous correction induces larger energy loss, the magnitude and pattern of this enhancement crucially depend on the form of viscous corrections used.
Comments:
10 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1801.00637 [pdf]
PRC(2018)·18 citations
06
[Submitted on 28 Dec 2017] (cross-list from astro-ph.HE)
Low-luminosity gamma-ray bursts as the sources of ultrahigh-energy cosmic ray nuclei
B. Theodore Zhang🇨🇳 · Kohta Murase🇺🇸 · Shigeo S. Kimura🇺🇸 · Shunsaku Horiuchi🇺🇸 · Peter Mészáros🇺🇸
Recent results from the Pierre Auger Collaboration have shown that the composition of ultrahigh-energy cosmic rays (UHECRs) becomes gradually heavier with increasing energy. Although gamma-ray bursts (GRBs) have been promising sources of UHECRs, it is still unclear whether they can account for the Auger results because of their unknown nuclear composition of ejected UHECRs. In this work, we revisit the possibility that low-luminosity GRBs (LL GRBs) act as the sources of UHECR nuclei, and give new predictions based on the intrajet nuclear composition models considering progenitor dependencies. We find that the nuclear component in the jet can be divided into two groups according to the mass fraction of silicon nuclei, Si-free and Si-rich. Motivated by the connection between LL GRBs and transrelativistic supernovae, we also consider the hypernova ejecta composition. Then, we discuss the survivability of UHECR nuclei in the jet base and internal shocks of the jets, and show that it is easier for nuclei to survive for typical LL GRBs. Finally, we numerically propagate UHECR nuclei ejected from LL GRBs with different composition models and compare the resulting spectra and composition to Auger data. Our results show that both the Si-rich progenitor and hypernova ejecta models match the Auger data well, while the Si-free progenitor models have more difficulty in fitting the spectrum. We argue that our model is consistent with the newly reported cross correlation between the UHECRs and starburst galaxies, since both LL GRBs and hypernovae are expected to be tracers of the star-formation activity. LL GRBs have also been suggested as the dominant origin of IceCube neutrinos in the PeV range, and the LL GRB origin of UHECRs can be critically tested by near-future multimessenger observations.
Comments:
17 pages, 16 figures, minor corrections, added the discussion about the possible correlation with starburst galaxies, version accepted by PRD
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1712.09984 [pdf]
PRD(2018)·113 citations
07
[Submitted on 29 Dec 2017] (cross-list from hep-th)
A quantum hydrodynamical description for scrambling and many-body chaos
Mike Blake🇺🇸 · Hyunseok Lee🇺🇸 · Hong Liu🇺🇸
Recent studies of out-of-time ordered thermal correlation functions (OTOC) in holographic systems and in solvable models such as the Sachdev-Ye-Kitaev (SYK) model have yielded new insights into manifestations of many-body chaos. So far the chaotic behavior has been obtained through explicit calculations in specific models. In this paper we propose a unified description of the exponential growth and ballistic butterfly spreading of OTOCs across different systems using a newly formulated "quantum hydrodynamics," which is valid at finite $ℏ$ and to all orders in derivatives. The scrambling of a generic few-body operator in a chaotic system is described as building up a "hydrodynamic cloud," and the exponential growth of the cloud arises from a shift symmetry of the hydrodynamic action. The shift symmetry also shields correlation functions of the energy density and flux, and time ordered correlation functions of generic operators from exponential growth, while leads to chaotic behavior in OTOCs. The theory also predicts an interesting phenomenon of the skipping of a pole at special values of complex frequency and momentum in two-point functions of energy density and flux. This pole-skipping phenomenon may be considered as a "smoking gun" for the hydrodynamic origin of the chaotic mode. We also discuss the possibility that such a hydrodynamic description could be a hallmark of maximally chaotic systems.
Comments:
48 pages, 9 figures. v2: references added, various clarifications made including an expanded discussion of predictions in the introduction and an expanded discussion of four-point functions, v3: journal version
Subjects:
High Energy Physics — Theory (hep-th); Strongly Correlated Electrons (cond-mat.str-el); nlin.CD (nlin.CD); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
1801.00010 [pdf]
JHEP(2018)·204 citations
08
[Submitted on 29 Dec 2017] (cross-list from astro-ph.HE)
On Cooling of Neutron Stars With Stiff Equation of State Including Hyperons
Hovik Grigorian · Evgeni E. Kolomeitsev · Konstantin A. Maslov · Dmitry N. Voskresensky
The existence of high mass ( $\sim 2 M_{⊙}$ ) pulsars PSR J1614-2230 and PSR J0348-0432 requires the compact star matter to be described by a stiff equation of state (EoS). Presence of hyperons in neutron stars leads to a softening of the EoS that results in a decrease of the maximum neutron-star mass below the measured values of masses for PSR J1614-2230 and PSR J0348-0432 pulsars if one exploits ordinary relativistic mean-field (RMF) models (hyperon puzzle). However, within an RMF EoS with a sigma-scaled hadron effective masses and coupling constants, the maximum neutron-star mass remains above $2 M_{⊙}$ even when hyperons are included. Also, other important constraints on the equation of state, e.g. the flow constraint from heavy-ion collisions are to be fulfilled. We demonstrate how a satisfactory explanation of all existing observational data for the temperature-age relation is reached within the "nuclear medium cooling" scenario with a relativistic-mean-field EoS with a sigma-scaled hadron effective masses and coupling constants including hyperons.
Comments:
5 pages, 4 figures, submitted to Universe journal by MDPI
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1801.00040 [pdf]
Universe(2018)·11 citations
09
[Submitted on 31 Dec 2017] (cross-list from hep-ph)
Comprehending Particle Production in Proton+Proton and Heavy-ion collisions at the Large Hadron Collider
Raghunath Sahoo🇮🇳
Particle production mechanisms in proton+proton and heavy-ion collisions at the LHC energies are discussed. An attempt is made to connect p+p to heavy-ion collisions in understanding the final state observables. New emerging phenomena like Multipartonic Interactions (MPI) and Color Reconnection (CR) mechanism are important in understanding heavy-ion like behaviors in high-multiplicity p+p events. Particle spectra, Multipartonic Interactions, Strangeness enhancement, Nuclear modification factor etc. are few of the aspects, which are discussed in this presentation.
Comments:
Invited Plenary Talk in DAE-Nuclear Physics Symposium-2017, Thapar University, Patiala, India
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1801.00252 [pdf]
DAE Symp.Nucl.Phys.(2017)·0 citations
10
[Submitted on 31 Dec 2017] (cross-list from hep-ph)
Goldstonic pseudoscalar mesons in Bethe-Salpeter-inspired setting
Wolfgang Lucha🇦🇹 · Franz F. Schoberl🇦🇹
For a two-particle bound-state equation closer to its Bethe-Salpeter origins than Salpeter's equation, with effective-interaction kernel deliberately forged such as to ensure, in the limit of zero mass of the bound-state constituents, the vanishing of the arising bound-state mass, we scrutinize the emerging features of the lightest pseudoscalar mesons for their agreement with the behaviour predicted by a generalization of the Gell-Mann-Oakes-Renner relation.
Comments:
12 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1801.00264 [pdf]
Int.J.Mod.Phys.A(2018)·2 citations
11
[Submitted on 31 Dec 2017] (cross-list from hep-ph)
Goldstone Modes and Clebsch-Gordan Coefficients
Xian-Zheng Bai🇨🇳 · Deshan Yang🇨🇳 · Da-Xin Zhang🇨🇳
We solve explicitly the Goldstone modes in spontaneously symmetry breaking models with supersymmetry. We find that, when more than one fields or representations contribute to the symmetry breaking, there exist identities among the Clebsch-Gordan coefficients which can be used as consistent checks on the calculations.
Comments:
13 pages
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1801.00300 [pdf]
NPB(2018)·0 citations
12
[Submitted on 31 Dec 2017] (cross-list from hep-ph)
Chiral phase transition at finite chemical potential in 2+1-flavor soft-wall AdS/QCD
Sean P. Bartz🇺🇸 · Theodore Jacobson🇺🇸
The phase transition from hadronic matter to chirally-symmetric quark-gluon plasma is expected to be a rapid crossover at zero quark chemical potential ( $μ$ ), becoming first order at some finite value of $μ$ , indicating the presence of a critical point. Using a three-flavor soft-wall model of AdS/QCD, we investigate the effect of varying the light and strange quark masses on the order of the chiral phase transition. At zero quark chemical potential, we reproduce the Columbia Plot, which summarizes the results of lattice QCD and other holographic models. We then extend this holographic model to examine the effects of finite quark chemical potential. We find that the the chemical potential does not affect the critical line that separates first-order from rapid crossover transitions. This excludes the possibility of a critical point in this model, suggesting that a different setup is necessary to reproduce all the features of the QCD phase diagram.
Comments:
14 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1801.00358 [pdf]
PRC(2018)·23 citations
13
[Submitted on 1 Jan 2018] (cross-list from hep-ph)
Tomography and gravitational radii for hadrons by three-dimensional structure functions
S. Kumano🇯🇵 · Qin-Tao Song🇯🇵 · O. V. Teryaev🇷🇺
Three-dimensional tomography of hadrons can be investigated by generalized parton distributions (GPDs), transverse-momentum-dependent parton distributions (TMDs), and generalized distribution amplitudes (GDAs). The GDA studies had been only theoretical for a long time because there was no experimental measurement until recently, whereas the GPDs and TMDs have been investigated extensively by deeply virtual Compton scattering and semi-inclusive deep inelastic scattering. Here, we report our studies to determine pion GDAs from recent KEKB measurements on the differential cross section of $γ^{*} γ \to π^{0} π^{0}$ . Since an exotic-hadron pair can be produced in the final state, the GDAs can be used also for probing internal structure of exotic hadron candidates in future. The other important feature of the GDAs is that the GDAs contain information on form factors of the energy-momentum tensor for quarks and gluons, so that gravitational form factors and radii can be calculated from the determined GDAs. We show the mass (energy) and the mechanical (pressure, shear force) form factors and radii for the pion. Our analysis should be the first attempt for obtaining gravitational form factors and radii of hadrons by analysis of actual experimental measurements. We believe that a new field of gravitational physics is created from the microscopic level in terms of elementary quarks and gluons.
Comments:
10 pages, LaTeX, 2 style files, 10 figure files, Proceedings of the International Conference on Exotic Atoms and Related Topics (EXA2017), September 10-15, 2017, Vienna, Austria
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1801.00526 [pdf]
EPJ Web Conf.(2018)·3 citations
14
[Submitted on 2 Jan 2018] (cross-list from hep-ph)
QCD Parameters Correlations from Heavy Quarkonia
Stephan Narison (LUPM-CNRS Montpellier-FR)🇫🇷
Correlations between the QCD coupling \alpha_s, the gluon condensate < \alpha_s G^2 >, and the c,b-quark running masses m_c,b in the MS-scheme are explicitly studied (for the first time) from the (axial-)vector and (pseudo)scalar charmonium and bottomium ratios of Laplace sum rules (LSR) evaluated at the \mu-subtraction stability point where PT @N2LO, N3LO and < \alpha_s G^2> @NLO corrections are included. Our results clarify the (apparent) discrepancies between different estimates of < \alpha_s G^2> from J/\psi sum rule but also shows the sensitivity of the sum rules on the choice of the \mu-subtraction scale which does not permit a high-precision estimate of m_c,b. We obtain from the (axial-)vector [resp. (pseudo)scalar] channels <\alpha_s G^2>=(8.5+- 3.0)> [resp. (6.34+-.39)] 10^-2 GeV^4, m_c(m_c)= 1256(30) [resp. 1266(16)] MeV and m_b(m_b)=4192(15) MeV. Combined with our recent determinations from vector channel, one obtains the average: m_c(m_c)= 1263(14) MeV and m_b(m_b) 4184(11) MeV. Adding our value of the gluon condensate with different previous estimates, we obtain the new sum rule average: <\alpha_s G^2>=(6.35+- 0.35) 10^-2 GeV^4. The mass-splittings M_\chi_0c(0b)-M_\eta_c(b) give @N2LO: \alpha_s(M_Z)=0.1183(19)(3) in good agreement with the world average (see more detailed discussions in the section: addendum). .
Comments:
22 pages, 1 Table, 16 Figures. Extended version of talks presented at QCD 17 (Montpellier-FR) and HEPMAD 16/17 (Antananarivo-MG). New Addendum where more detailed discussions on the extraction of alpha_s from the M_\chi_0c(0b)-M_\eta_c(b) mass-splittings are given
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1801.00592 [pdf]
Int.J.Mod.Phys.A(2018)·92 citations

Affiliations

first authorsco-authorsvia INSPIRE