Nuclear Theory·nucl-th

Tuesday·December 19, 2017

24 papers—17 primary·7 cross-listed

01
[Submitted on 15 Dec 2017]
Multi moment cancellation of participant fluctuations
Viktor Begun🇵🇱 · Maja Mackowiak-Pawlowska🇵🇱
We summarize the new method for the correction of participant fluctuations in high energy nucleus-nucleus collisions. It allows to estimate a fluctuation baseline in comparison to a useful signal. In particular cases of a weak signal compared to baseline, it allows to cancel the baseline contribution from participants.
Comments:
Talk at Critical Point and Onset of Deconfinement - CPOD2017
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1712.05805 [pdf]
PoS(2018)·1 citation
02
[Submitted on 15 Dec 2017]
Chiral Light Front Perturbation Theory and the Flavor Dependence of the Light-Quark Nucleon Sea
Mary Alberg🇺🇸 · Gerald A. Miller🇺🇸
The light-quark flavor dependence of the proton sea has been of great interest for many years because of its close connection with non-perturbative effects. One hypothesis is that this dependence arises from the pion cloud of the proton. We apply light cone perturbation theory and experimental constraints to a chiral Lagrangian to compute the relevant Fock-space components of the nucleon wave function with well-defined uncertainties. Existing experimental information regarding the light flavor sea is studied, and predictions for future experimental results are provided. Future experiments have the ability to rule out this hypothesis and have profound implications for understanding the nucleon-nucleon force.
Comments:
10 pages, 8 figures - text expanded, figures and references added, published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1712.05814 [pdf]
PRC(2019)·27 citations
03
[Submitted on 15 Dec 2017]
Relativistic Fluid Dynamics In and Out of Equilibrium -- Ten Years of Progress in Theory and Numerical Simulations of Nuclear Collisions
Paul Romatschke🇺🇸 · Ulrike Romatschke🇺🇸
Ten years ago, relativistic viscous fluid dynamics was formulated from first principles in an effective field theory framework, based entirely on the knowledge of symmetries and long-lived degrees of freedom. In the same year, numerical simulations for the matter created in relativistic heavy-ion collision experiments became first available, providing constraints on the shear viscosity in QCD. The field has come a long way since then. We present the current status of the theory of non-equilibrium fluid dynamics in 2017, including the divergence of the fluid dynamic gradient expansion, resurgence, non-equilibrium attractor solutions, the inclusion of thermal fluctuations as well as their relation to microscopic theories. Furthermore, we review the theory basis for numerical fluid dynamics simulations of relativistic nuclear collisions, and comparison of modern simulations to experimental data for nucleus-nucleus, nucleus-proton and proton-proton collisions.
Comments:
214 pages, 26 figures; uninvited review; v2: typos fixed, references added; v3: more typos fixed, full version available as a book (email for discount)
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Theory (hep-th)
arXiv:
1712.05815 [pdf]
443 citations
04
[Submitted on 15 Dec 2017]
Structure of the exotic $^{9}$ He nucleus from the no-core shell model with continuum
Matteo Vorabbi🇨🇦 · Angelo Calci🇨🇦 · Petr Navratil🇨🇦 · Michael K.G Kruse🇺🇸 · Sofia Quaglioni🇺🇸 · Guillaume Hupin🇫🇷
The exotic $^{9}$ He nucleus, which presents one of the most extreme neutron-to-proton ratios, belongs to the $N = 7$ isotonic chain famous for the phenomenon of ground-state parity inversion with decreasing number of protons. Consequently, it would be expected to have an unnatural (positive) parity ground state similar to $^{11}$ Be and $^{10}$ Li. Despite many experimental and theoretical investigations, its structure remains uncertain. Apart from the fact that it is unbound, other properties including the spin and parity of its ground state and the very existence of additional low-lying resonances are still a matter of debate. In this work we study the properties of $^{9}$ He by analyzing the $n +^{8}$ He continuum in the context of the ab initio no-core shell model with continuum (NCSMC) formalism with chiral interactions as the only input. The NCSMC is a state-of-the-art approach for the ab initio description of light nuclei. With its capability to predict properties of bound states, resonances, and scattering states in a unified framework, the method is particularly well suited for the study of unbound nuclei such as $^{9}$ He. Our analysis produces an unbound $^{9}$ He nucleus. Two resonant states are found at the energies of $\sim 1$ and $\sim 3.5$ MeV, respectively, above the $n +^{8}$ He breakup threshold. The first state has a spin-parity assignment of $J^{π} = 1/2^{-}$ and can be associated with the ground state of $^{9}$ He, while the second, broader state has a spin-parity of $3/2^{-}$ . No resonance is found in the $1/2^{+}$ channel, only a very weak attraction. We find that the $^{9}$ He ground-state resonance has a negative parity and thus breaks the parity-inversion mechanism found in the $^{11}$ Be and $^{10}$ Li nuclei of the same $N = 7$ isotonic chain.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1712.05824 [pdf]
PRC(2018)·18 citations
05
[Submitted on 15 Dec 2017]
Revisiting the role of the $(n, γ f)$ process in the low-energy fission of $^{235}$ U and $^{239}$ Pu
J. Eric Lynn🇺🇸 · Patrick Talou🇺🇸 · Olivier Bouland🇫🇷
The $(n, γ f)$ process is reviewed in light of modern nuclear reaction calculations in both slow and fast neutron-induced fission reactions on $^{235}$ U and $^{239}$ Pu. Observed fluctuations of the average prompt fission neutron multiplicity and average total $γ$ -ray energy below 100 eV incident neutron energy are interpreted in this framework. The surprisingly large contribution of the M1 transitions to the pre-fission $γ$ -ray spectrum of $^{239}$ Pu is explained by the dominant fission probabilities of 0 $^{+}$ and $2^{+}$ transition states, which can only be accessed from compound nucleus states formed by the interaction of $s$ -wave neutrons with the target nucleus in its ground state, and decaying through M1 transitions. The impact of an additional low-lying M1 scissors mode in the photon strength function is analyzed. We review experimental evidence for fission fragment mass and kinetic energy fluctuations in the resonance region and their importance in the interpretation of experimental data on prompt neutron data in this region. Finally, calculations are extended to the fast energy range where $(n, γ f)$ corrections can account for up to 3\% of the total fission cross section and about 20\% of the capture cross section.
Comments:
14 pages, 19 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1712.05856 [pdf]
PRC(2018)·9 citations
06
[Submitted on 16 Dec 2017]
The moment of inertia of the neutron star PSR J0348+0432 and its proto neutron star
Xian-Feng Zhao
The difference of the moment of inertia of the neutron star PSR J0348 + 0432 and that of its proto neutron star is studied in the framework of the relativistic mean field theory considering baryon octet. The temperature of the proto neutron star PSR J0348+0432 is chosen as T=5 MeV. The calculations show that the central baryon number density of the proto neutron star PSR J0348+0432 is in the range 0.623 $\sim$ 0.813 fm $^{- 3}$ , decreased by 2 $\sim$ 7\% compared to that of the neutron star PSR J0348+0432. The radius of the proto neutron star PSR J0348+0432 is in the range 13.101 $\sim$ 12.419 km, increased by 1 $\sim$ 2\% compared to that of the neutron star PSR J0348+0432. The moment of inertia of the proto neutron star PSR J0348+0432 is in the range 1.939 $\times$ 10 $^{45}$ $\sim$ 1.638 $\times$ 10 $^{45}$ g.cm $^{2}$ , increased by about 2 $\sim$ 7\% compared to that of the neutron star PSR J0348+0432.
Comments:
5 pages,5 figures, published by Astrophys Space Sci,2017,362(5):95
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1712.05894 [pdf]
Astrophys.Space Sci.(2017)·7 citations
07
[Submitted on 16 Dec 2017]
Bulk viscosity of strongly interacting matter in the relaxation time approximation
Alina Czajka🇨🇦 · Sigtryggur Hauksson🇨🇦 · Chun Shen🇺🇸 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦
This paper presents how thermal mean field effects are incorporated consistently in the hydrodynamical modelling of heavy-ion collisions. The nonequilibrium correction to the distribution function resulting from a temperature-dependent mass is obtained in a procedure which automatically satisfies the Landau matching condition and is thermodynamically consistent. The physics of the bulk viscosity is studied here for Boltzmann and Bose-Einstein gases within the Chapman-Enskog and 14-moment approaches in the relaxation time approximation. Constant and temperature-dependent masses are considered in turn. It is shown that, in the small mass limit, both methods lead to the same value of the ratio of the bulk viscosity over its relaxation time. The inclusion of a temperature-dependent mass leads to the emergence of the $β_{λ}$ -function in that ratio, and it is of the expected parametric form for the Boltzmann gas, while for the Bose-Einstein case it is affected by the infrared cut-off. This suggests that the relaxation time approximation may be too crude to obtain a reliable form of $ζ / τ_{R}$ for gases obeying Bose-Einstein statistics.
Comments:
version published in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1712.05905 [pdf]
PRC(2018)·33 citations
08
[Submitted on 16 Dec 2017]
Nuclear skin and the curvature of the symmetry energy
Ad. R. Raduta (IFIN-HH, Bucharest)🇷🇴 · F. Gulminelli (LPC, Caen)🇫🇷
The effect of correlations between the slope and the curvature of the symmetry energy on ground state nuclear observables is studied within the extended Thomas-Fermi approximation. We consider different isovector probes of the symmetry energy, with a special focus on the skin of $^{208} Pb$ . We use a recently proposed meta-modelling technique to generate a large number of equation of state models, where the empirical parameters are independently varied. The results are compared to a set of calculations using 17 different Skyrme interactions. We show that the curvature parameter plays a non-negligible role on the neutron skin, while the effect is reduced in Skyrme functionals because of the correlation with the slope parameter.
Comments:
10 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1712.05973 [pdf]
PRC(2018)·15 citations
09
[Submitted on 16 Dec 2017]
Status of the Theoretical Calculation of Nuclear Electric Dipole Moment
Nodoka Yamanaka🇫🇷
The electric dipole moment is a very sensitive probe of CP violation beyond the standard model. Light nuclei are particularly interesting since the CP violation may be enhanced by nuclear many-body effects. In this proceeding, we present the current status of the theoretical evaluations of the electric dipole moment of light nuclei in the ab initio approach and in the cluster model. We add the preliminary result of the evaluation of the electric dipole moment of $^{7}$ Li which is treated in a cluster model with a triton.
Comments:
4 pages, 1 figures, proceeding of Ito International Research Center (IIRC) symposium "Perspectives of the physics of nuclear structure", November 1-4, 2017
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1712.06001 [pdf]
JPS Conf.Proc.(2018)·2 citations
10
[Submitted on 17 Dec 2017]
Chiral Symmetry Restoration and Quark Deconfinement beyond Mean Field in a Magnetized PNJL Model
Shijun Mao🇨🇳
We study chiral symmetry restoration and quark deconfinement beyond mean field approximation in a magnetized PNJL model. The feedback from mesons to quarks modifies the quark coupling constant and Polyakov potential. As a result, the separate critical temperatures for the two phase transitions at mean field level coincide and the magnetic catalysis becomes inverse magnetic catalysis, when the meson contribution is included.
Comments:
5 pages,3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1712.06062 [pdf]
PRD(2018)·19 citations
11
[Submitted on 17 Dec 2017]
Proton skins, neutron skins, and proton radii of mirror nuclei
Francesca Sammarruca
We present predictions for proton skins based on isospin-asymmetric equations of state derived microscopically from high-precision chiral few-nucleon interactions. Moreover, we investigate the relation between the neutron skin of a nucleus and the difference between the proton radii of the corresponding mirror nuclei.
Comments:
8 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1712.06167 [pdf]
Front.in Phys.(2018)·10 citations
12
[Submitted on 18 Dec 2017]
Phenomenological QCD equations of state for neutron star mergers, a talk presented at CPOD17
Toru Kojo🇨🇳
We delineate the properties of dense QCD matter through equations of state constrained by the neutron star observations. The two solar mass constraint, the radius constraint of 11-13 km, and the causality constraint on the speed of sound, are used to develop the picture of hadron-quark continuity in which hadronic matter continuously transforms into quark matter. A unified equation of state at zero temperature and beta-equilibrium is constructed by a phenomenological interpolation between nuclear and quark matter equations of state. For applications to supernovae and neutron star mergers, the unified equation of state is perturbed by temperature corrections.
Comments:
13 pages, 9 figures, a talk presented at Critical Point and Onset of Deconfinement, 7-11 August, 2017, The Wang Center, Stony Brook University, Stony Brook, NY
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
1712.06255 [pdf]
PoS(2018)·1 citation
13
[Submitted on 18 Dec 2017]
Possible $η^{'} d$ bound state and its $s$ -channel formation in the $γ d \to η d$ reaction
Takayasu Sekihara (JAEA, Ibaraki)🇯🇵 · Hiroyuki Fujioka (Kyoto U.)🇯🇵 · Takatsugu Ishikawa (ELPH, Tohoku Univ.)🇯🇵
We theoretically investigate a possibility of an $η^{'} d$ bound state and its formation in the $γ d \to η d$ reaction. First, in the fixed center approximation to the Faddeev equations we obtain an $η^{'} d$ bound state with a binding energy of 25 MeV and width of 19 MeV, where we take the $η^{'} N$ interaction with a coupling to the $η N$ channel from the linear $σ$ model. Then, in order to investigate the feasibility from an experimental point of view, we calculate the cross section of the $γ d \to η d$ reaction at the photon energy in the laboratory frame around 1.2 GeV. As a result, we find a clear peak structure with the strength $\sim$ 0.2 nb/sr, corresponding to a signal of the $η^{'} d$ bound state in case of backward $η$ emission. This structure will be prominent because a background contribution coming from single-step $η$ emission off a bound nucleon is highly suppressed. In addition, the signal can be seen even in case of forward $η$ emission as a bump or dip, depending on the relative phase between the bound-state formation and the single-step background.
Comments:
9 pages, 13 eps figures, version accepted for publication in PRC, description of the discussion part is improved
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1712.06257 [pdf]
PRC(2018)·5 citations
14
[Submitted on 18 Dec 2017]
Why {\em Explicit} Strangeness Is Not Relevant In Compact Stars
Mannque Rho🇫🇷
Drawing largely from my work with co--workers, I present arguments that strangeness does not play an {\it explicit} role in compact-star matter. They are based on the skyrmion description of dense matter combined with Wilsoninan renormalization group approach to kaon nuclear interactions. The key idea is that quark degrees of freedom, carrying strangeness, can be traded in by topology for hadron degrees of freedom.
Comments:
11 pages, 6 figures. arXiv admin note: text overlap with arXiv:1407.1611
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1712.06284 [pdf]
1 citation
15
[Submitted on 18 Dec 2017]
In-medium thermal conductivity and diffusion coefficients of a hot hadronic gas mixture
Utsab Gangopadhyaya🇮🇳 · Snigdha Ghosh🇮🇳 · Sourav Sarkar🇮🇳
The relativistic kinetic theory approach has been employed to study four well-known transport coefficients that characterize heat flow and diffusion for the case of a hot mixture constituting of nucleons and pions. Medium effects on the cross-section for binary collisions ( $N π$ , $π π$ ) have been taken into consideration by incorporating self-energy corrections to modify the propagator of the exchanged $Δ$ baryon in $N π$ interaction and the $ρ$ and $σ$ meson propagators for the case of $π π$ interaction. The temperature dependence of the four coefficients have been investigated for several values of the baryon chemical potential.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1712.06287 [pdf]
IJMPE(2019)·2 citations
16
[Submitted on 18 Dec 2017]
Antiproton-nucleus quasi-bound states within the 2009 version of the Paris $N ˉ N$ potential
Jaroslava Hrtánková🇨🇿 · Jiří Mareš🇨🇿
We studied the $p ˉ$ interactions with the nuclear medium within the 2009 version of the Paris $N ˉ N$ potential model. We constructed the $p ˉ$ --nucleus optical potential using the Paris $S$ - and $P$ -wave $p ˉ N$ scattering amplitudes and treated their strong energy and density dependence self-consistently. We considered a phenomenological $P$ -wave term as well. We calculated $p ˉ$ binding energies and widths of the $p ˉ$ bound in various nuclei. The $P$ -wave potential has very small effect on the calculated $p ˉ$ binding energies, however, it reduces the corresponding widths noticeably. Moreover, the $S$ -wave potential based on the Paris amplitudes supplemented by a phenomenological $P$ -wave term yields the $p ˉ$ binding energies and widths in very good agreement with those obtained within the RMF model consistent with $p ˉ$ -atom data.
Comments:
7 pages, 4 figures, proceedings of the EXA2017 conference, Vienna, Austria, September 11 - 15, 2017
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1712.06416 [pdf]
EPJ Web Conf.(2018)·1 citation
17
[Submitted on 18 Dec 2017]
Application of Coulomb energy density functional for atomic nuclei: Case studies of local density approximation and generalized gradient approximation
Tomoya Naito · Ryosuke Akashi · Haozhao Liang
We test the Coulomb exchange and correlation energy density functionals of electron systems for atomic nuclei in the local density approximation (LDA) and the generalized gradient approximation (GGA). For the exchange Coulomb energies, it is found that the deviation between the LDA and GGA ranges from around $11 %$ in $^{4} He$ to around $2.2 %$ in $^{208} Pb$ , by taking the Perdew-Burke-Ernzerhof (PBE) functional as an example of the GGA\@. For the correlation Coulomb energies, it is shown that those functionals of electron systems are not suitable for atomic nuclei.
Comments:
22 pages, 9 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th); cond-mat.other (cond-mat.other); Nuclear Experiment (nucl-ex)
arXiv:
1712.06490 [pdf]
PRC(2018)·12 citations
18
[Submitted on 16 Dec 2017] (cross-list from cond-mat.quant-gas)
An exact solution to the Bertsch problem and the non-universality of the Unitary Fermi Gas
E. Ruiz Arriola🇪🇸 · S. Szpigel🇧🇷 · V. S. Timoteo🇧🇷
We analyze the universality of the Unitary Fermi Gas in its ground state from a Wilsonian renormalization point of view and compute the effective range dependence of the Bertsch parameter $ξ$ exactly. To this end we construct an effective block-diagonal two-body separable interaction with the Fermi momentum as a cut-off which reduces the calculation to the mean field level. The interaction is separable in momentum space and is determined by Tabakin's inverse scattering formula. For a vanishing effective range we get $ξ = \frac{176}{9 π} - \frac{17}{3} = 0.56$ . By using phase-equivalent similarity transformations we can show that there is a class of exact solutions with any value in the range $0.56 \geq ξ \geq - 1/3$ .
Comments:
5 pages, 2 figures
Subjects:
Quantum Gases (cond-mat.quant-gas); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1712.05931 [pdf]
2 citations
19
[Submitted on 17 Dec 2017] (cross-list from astro-ph.SR)
The Impact of Nuclear Reaction Rate Uncertainties On The Evolution of Core-Collapse Supernova Progenitors
C. E. Fields · F. X. Timmes · R. Farmer · I. Petermann · William M. Wolf · S. M. Couch
We explore properties of core-collapse supernova progenitors with respect to the composite uncertainties in the thermonuclear reaction rates by coupling the reaction rate probability density functions provided by the STARLIB reaction rate library with $MESA$ stellar models. We evolve 1000 15 $M_{⊙}$ models from the pre main-sequence to core O-depletion at solar and subsolar metallicities for a total of 2000 Monte Carlo stellar models. For each stellar model, we independently and simultaneously sample 665 thermonuclear reaction rates and use them in a $MESA$ in situ reaction network that follows 127 isotopes from $^{1}$ H to $^{64}$ Zn. With this framework we survey the core mass, burning lifetime, composition, and structural properties at five different evolutionary epochs. At each epoch we measure the probability distribution function of the variations of each property and calculate Spearman Rank-Order Correlation coefficients for each sampled reaction rate to identify which reaction rate has the largest impact on the variations on each property. We find that uncertainties in $^{14}$ N $(p, γ)^{15}$ O, triple- $α$ , $^{12}$ C $(α, γ)^{16}$ O, $^{12}$ C( $^{12}$ C, $p$ ) $^{23}$ Na, $^{12}$ C( $^{16}$ O, $p$ ) $^{27}$ Al, $^{16}$ O( $^{16}$ O, $n$ ) $^{31}$ S, $^{16}$ O( $^{16}$ O, $p$ ) $^{31}$ P, and $^{16}$ O( $^{16}$ O, $α$ ) $^{28}$ Si reaction rates dominate the variations of the properties surveyed. We find that variations induced by uncertainties in nuclear reaction rates grow with each passing phase of evolution, and at core H-, He-depletion are of comparable magnitude to the variations induced by choices of mass resolution and network resolution. However, at core C-, Ne-, and O-depletion, the reaction rate uncertainties can dominate the variation causing uncertainty in various properties of the stellar model in the evolution towards iron core-collapse.
Comments:
Accepted for publication in ApJS, 33 pages, 21 figures
Subjects:
Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1712.06057 [pdf]
Astrophys.J.Suppl.(2018)·34 citations
20
[Submitted on 17 Dec 2017] (cross-list from hep-ph)
Relativistic corrections to exclusive $χ_{c J} + γ$ production from $e^{+} e^{-}$ annihilation
Nora Brambilla🇩🇪 · Wen Chen🇨🇳 · Yu Jia🇨🇳 · Vladyslav Shtabovenko🇩🇪 · Antonio Vairo🇩🇪
We calculate in the non-relativistic QCD (NRQCD) factorization framework all leading relativistic corrections to the exclusive production of $χ_{c J} + γ$ in $e^{+} e^{-}$ annihilation. In particular, we compute for the first time contributions induced by octet operators with a chromoelectric field. The matching coefficients multiplying production long distance matrix elements (LDMEs) are determined through perturbative matching between QCD and NRQCD at the amplitude level. Technical challenges encountered in the non-relativistic expansion of the QCD amplitudes are discussed in detail. The main source of uncertainty comes from the not so well known LDMEs. Accounting for it, we provide the following estimates for the production cross sections at $s = 10.6 GeV$ : $σ (e^{+} e^{-} \to χ_{c 0} + γ) = (1.3 \pm 0.4) fb$ , $σ (e^{+} e^{-} \to χ_{c 1} + γ) = (15.4 \pm 6.7) fb$ , and $σ (e^{+} e^{-} \to χ_{c 2} + γ) = (4.7 \pm 2.6) fb$ .
Comments:
Journal version. 43 pages, 7 figures; V4: Eqs. (12), (46k), (49) and (55-57) corrected. This also affects some of the following formulas and the numerical results. Changes are detailed in the Erratum to Phys. Rev. D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1712.06165 [pdf]
PRD(2018)·22 citations
21
[Submitted on 17 Dec 2017] (cross-list from hep-th)
Hydrodynamic Excitations from Chiral Kinetic Theory and the Hydrodynamic Frames
Navid Abbasi🇮🇷 · Kiarash Naderi🇮🇷 · Farid Taghinavaz🇮🇷
In the framework of chiral kinetic theory (CKT), we consider a system of right- and left-handed Weyl fermions out of thermal equilibrium in a homogeneous weak magnetic field. We show that the Lorentz invariance implies a modification in the definition of the momentum current in the phase space, compared to the case in which the system is in global equilibrium. Using this modified momentum current, we derive the linearized conservation equations from the kinetic equation up to second order in the derivative expansion. It turns out that the eigenmodes of these equations, namely the hydrodynamic modes, differ from those obtained from the hydrodynamic in the Landau-Lifshitz (LL) frame at the same order. We show that the modes of the former case may be transformed to the corresponding modes in the latter case by a global boost. The velocity of the boost is proportional to the magnetic field as well as the difference between the right- and left-handed charges susceptibility. We then compute the chiral transport coefficients in a system of non-Abelian chiral fermions in the no-drag frame and by making the above boost, obtain the well-known transport coeffiecients of the system in the LL frame. Finally by using the idea of boost, we reproduce the AdS/CFT result for the chiral drag force exerted on a quark at rest in the rest frame of the fluid, without performing any holographic computations.
Comments:
35 pages
Subjects:
High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1712.06175 [pdf]
JHEP(2018)·10 citations
22
[Submitted on 18 Dec 2017] (cross-list from hep-ph)
Two Gluon Emission from MHV: Two Particle Correlations and the Deviation from Poisson
A. N. Rasoanaivo🇿🇦 · W. A. Horowitz🇿🇦
We derive the momentum distribution for two soft and collinear gluons emitted from an off-shell quark, modeled by a $q γ \to q g g$ scattering process and computed using the maximal helicity violating (MHV) technique. We find the explicit non-Abelian corrections to the independent emission Poisson distribution in QED and demonstrate the efficiency of the MHV technique in perturbative QCD calculations. The gluonic two particle correlation function is highly suggestive of that measured in high-multiplicity $pp$ and $p A$ collisions, with a tight correlation in angle but broad correlation in rapidity. Further, the autocorrelation generated by the non-Abelian correlation can provide a significant non-hydrodynamical source of $v_{2}$ in these high multiplicity $pp$ and $p A$ collisions. Finally, these two gluon correlations can be used to calibrate Monte Carlo shower codes for a more accurate description of QCD processes in $pp$ collisions.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1712.06292 [pdf]
2 citations
23
[Submitted on 18 Dec 2017] (cross-list from hep-th)
Holographic three flavor baryon in the Witten-Sakai-Sugimoto model with the D0-D4 background
Wenhe Cai🇨🇳 · Si-wen Li🇨🇳
With the construction of the Witten-Sakai-Sugimoto model in the D0-D4 background, we systematically investigate the holographic baryon spectrum in the case of three flavors. The background geometry in this model is holographically dual to $U (N_{c})$ Yang-Mills theory in large $N_{c}$ limit involving an excited state with a nonzero $θ$ angle or glue condensate $⟨ Tr F \land F ⟩ = 8 π^{2} N_{c} κ ~$ , which is proportional to the charge density of the smeared D0-branes through a parameter $b$ or $κ ~$ . The classical solution of baryon in this model can be modified by embedding the Belavin-Polyakov-Schwarz-Tyupkin (BPST) instanton and we carry out the quantization of the collective modes with this solution. Then we extend the analysis to include the heavy flavor and find that the heavy meson is always bound in the form of the zero mode of the flavor instanton in strong coupling limit. The mass spectrum of heavy-light baryons in the situation with single- and double-heavy baryon is derived by solving the eigen equation of the quantized collective Hamiltonian. Afterwards we obtain that the constraint of stable baryon states has to be $1 < b < 3$ and the difference in the baryon spectrum becomes smaller as the D0 charge increases. It indicates that quarks or mesons can not form stable baryons if the $θ$ angle or glue condensate is sufficiently large. Our work is an extension of the previous study of this model and also agrees with those conclusions.
Comments:
35 pages, 2 figures, 1 table, this version includes the acknowledgement and some revisions
Subjects:
High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1712.06304 [pdf]
EPJC(2018)·5 citations
24
[Submitted on 18 Dec 2017] (cross-list from hep-ph)
Accessing Quark Helicity through Dihadron Studies
Hrayr H. Matevosyan🇦🇺 · Aram Kotzinian🇦🇲 · Anthony W. Thomas🇦🇺
We present a new proposal to study the helicity-dependent dihadron fragmentation functions (DiFF), which describe the correlations of the longitudinal polarization of a fragmenting quark with the transverse momenta of the produced hadron pair. Recent experimental searches for this DiFF via azimuthal asymmetries in back-to-back hadron pair production in $e^{+} e^{-}$ annihilation by the $BELLE$ Collaboration did not yield a signal. Here we propose a new way to access this DiFF in $e^{+} e^{-}$ annihilation, motivated by the recently recalculated cross section of this reaction, which explains why there was in fact no signal for the $BELLE$ Collaboration to see. In this new approach the azimuthal asymmetry is weighted by the virtual photon's transverse momentum square multiplying sine and cosine functions of difference of azimuthal angles of relative and total momentum for each pair. The integration over the virtual photon's transverse momentum has the effect of separating the convolution between the helicity-dependent DiFFs in the quark and antiquark jets and results in a nonzero collinear expression containing Fourier moments of helicity-dependent DiFFs. A second new measurement is also proposed for two-hadron production in semi-inclusive deep inelastic scattering, where the asymmetry is weighted in a similar way for a single pair. This results in a collinear factorized form of the asymmetry, which includes the quark helicity parton distribution function and the same helicity-dependent DiFF as in $e^{+} e^{-}$ production and will allow us to check the universality of this DiFF.
Comments:
5 pages, 1 figure. V3: Updated to version published in PRL with minor revisions of the text and an added reference
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1712.06384 [pdf]
PRL(2018)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE