Nuclear Theory·nucl-th

Tuesday·September 26, 2017

15 papers—5 primary·10 cross-listed

01
[Submitted on 22 Sept 2017]
Isospin Effect in Three-Body Kaonic Clusters
I. Filikhin · B. Vlahovic
The kaonic clusters $K^{-} K^{-} p$ and $pp K^{-}$ are described based on the configuration space Faddeev equations for $AA B$ system. The $A B$ interaction is given by isospin-dependent potentials. For this isospin model, we show that the relation $∣ E_{3} (V_{AA} = 0) ∣ < 2 ∣ E_{2} ∣$ is satisfied when $E_{2}$ is the binding energy of the $A B$ subsystem and $E_{3} (V_{AA} = 0)$ is the three-body binding energy when interaction between identical particles is omitted, $V_{AA} = 0$ . For the $N N K ˉ$ system, taking into account weak attraction of $N N$ interaction the relation leads to the evaluation $∣ E_{3} ∣ \leq 2∣ E_{2} ∣$ . The "isospinless model" for the kaonic clusters based on the isospin averaged $N K ˉ$ potential demonstrates the opposite relation $∣ E_{3} (V_{AA} = 0) ∣ > 2 ∣ E_{2} ∣$ . The isospin "given charge formalism" is presented for $N N K ˉ$ cluster. This formalism is related to isospin model by unitary transformation of the isospin basis. An interpretation of the "particle representation" for $N N K ˉ$ system is proposed.
Comments:
19 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1709.07967 [pdf]
AIP Conf.Proc.(2019)·1 citation
02
[Submitted on 23 Sept 2017]
Quest for consistent modelling of statistical decay of the compound nucleus
Tathagata Banerjee · S. Nath · Santanu Pal
A statistical model description of heavy ion induced fusion-fission reactions is presented where shell effects, collective enhancement of level density, tilting away effect of compound nuclear spin and dissipation are included. It is shown that the inclusion of all these effects provides a consistent picture of fission where fission hindrance is required to explain the experimental values of both pre-scission neutron multiplicities and evaporation residue cross-sections in contrast to some of the earlier works where a fission hindrance is required for pre-scission neutrons but a fission enhancement for evaporation residue cross-sections.
Comments:
14 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1709.08029 [pdf]
PLB(2018)·20 citations
03
[Submitted on 25 Sept 2017]
Effective description of hot QCD medium in strong magnetic field and longitudinal conductivity
Manu Kurian🇮🇳 · Vinod Chandra🇮🇳
Hot QCD medium effects have been studied in the effective quasi-particle description of quark-gluon plasma. This model encodes the collective excitation of gluons and quarks/anti-quarks in the thermal medium in terms of effective quarks and gluons having non-trivial energy dispersion relation. The present investigation involves the extension of the effective quasi-particle model in strong magnetic field limit. Realizing, hot QCD medium in the strong magnetic field as an effective grand canonical system in terms of the modified quark, anti-quark and gluonic degrees of freedom, the thermodynamics has been studied. Further, the Debye mass in hot QCD medium has to be sensitive to the magnetic field, and subsequently the same has been observed for the effective hot QCD coupling. As an implication, electrical conductivity (longitudinal) has been studied within an effective kinetic theory description of hot QCD in the presence of the strong magnetic field. The hot QCD equation of state (EoS), dependence entering through the effective coupling and quasi-parton distribution function, found to have a significant impact on the longitudinal electrical conductivity in strong magnetic field background.
Comments:
12 pages, 8 figures, two column
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1709.08320 [pdf]
PRD(2017)·73 citations
04
[Submitted on 21 Sept 2017]
What makes the peak structure of the $Λ p$ invariant-mass spectrum in the $K^{-}^{3} He \to Λ p n$ reaction?
Takayasu Sekihara (JAEA, Ibaraki)🇯🇵 · Eulogio Oset (Valencia U. & Valencia U., IFIC)🇪🇸 · Angels Ramos (Barcelona U., ECM & ICC, Barcelona U.)🇪🇸
Recently a peak structure was observed near the $K^{-} pp$ threshold in the in-flight $^{3} He (K^{-}, Λ p) n$ reaction of the E15 experiment at J-PARC, which could be a signal of a $K ˉ N N$ bound state. In order to investigate what is the origin of this peak, we calculate the cross section of this reaction, in particular based on the scenario that the $K ˉ N N$ bound state is indeed generated and decays into $Λ p$ . We find that the numerical result of the $Λ p$ invariant-mass spectrum in the $K ˉ N N$ bound scenario is consistent with the J-PARC E15 data.
Comments:
6 pages, 6 EPS figures, talk given at the 2nd Jagiellonian Symposium on Fundamental and Applied Subatomic Physics, Krakow, Poland, 4-9 June, 2017
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1709.08487 [pdf]
Acta Phys.Polon.B(2017)·2 citations
05
[Submitted on 25 Sept 2017]
Thouless-Valatin Rotational Moment of Inertia from the Linear Response Theory
K. Petrík · M. Kortelainen
Spontaneous breaking of continuous symmetries of a nuclear many-body system results in appearance of zero-energy restoration modes. Such modes introduce a non-physical contributions to the physical excitations called spurious Nambu-Goldstone modes. Since they represent a special case of collective motion, they are sources of important information about the Thouless-Valatin inertia. The main purpose of this work is to study the Thouless-Valatin rotational moment of inertia as extracted from the Nambu-Goldstone restoration mode that results from the zero-frequency response to the total angular momentum operator. We examine the role and effects of the pairing correlations on the rotational characteristics of heavy deformed nuclei in order to extend our understanding of superfluidity in general. We use the finite amplitude method of the quasiparticle random phase approximation on top of the Skyrme energy density functional framework with the Hartree-Fock-Bogoliubov theory. We have successfully extended this formalism and established a practical method for extracting the Thouless-Valatin rotational moment of inertia from the strength function calculated in the symmetry restoration regime. Our results reveal the relation between the pairing correlations and the moment of inertia of axially deformed nuclei of rare-earth and actinide regions of the nuclear chart. We have also demonstrated the feasibility of the method for obtaining the moment of inertia for collective Hamiltonian models. We conclude that from the numerical and theoretical perspective, the finite amplitude method can be widely used to effectively study rotational properties of deformed nuclei within modern density functional approaches.
Comments:
10 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1709.08534 [pdf]
PRC(2018)·14 citations
06
[Submitted on 22 Sept 2017] (cross-list from astro-ph.HE)
Evidence for a maximum mass cut-off in the neutron star mass distribution and constraints on the equation of state
Justin Alsing🇺🇸 · Hector O. Silva🇺🇸 · Emanuele Berti🇺🇸
We infer the mass distribution of neutron stars in binary systems using a flexible Gaussian mixture model and use Bayesian model selection to explore evidence for multi-modality and a sharp cut-off in the mass distribution. We find overwhelming evidence for a bimodal distribution, in agreement with previous literature, and report for the first time positive evidence for a sharp cut-off at a maximum neutron star mass. We measure the maximum mass to be $2.0 M_{⊙} < m_{max} < 2.2 M_{⊙}$ (68\%), $2.0 M_{⊙} < m_{max} < 2.6 M_{⊙}$ (90\%), and evidence for a cut-off is robust against the choice of model for the mass distribution and to removing the most extreme (highest mass) neutron stars from the dataset. If this sharp cut-off is interpreted as the maximum stable neutron star mass allowed by the equation of state of dense matter, our measurement puts constraints on the equation of state. For a set of realistic equations of state that support $> 2 M_{⊙}$ neutron stars, our inference of $m_{max}$ is able to distinguish between models at odds ratios of up to $12 : 1$ , whilst under a flexible piecewise polytropic equation of state model our maximum mass measurement improves constraints on the pressure at $3 - 7 \times$ the nuclear saturation density by $\sim 30 - 50%$ compared to simply requiring $m_{max} > 2 M_{⊙}$ . We obtain a lower bound on the maximum sound speed attained inside the neutron star of $c_{s}^{max} > 0.63 c$ (99.8\%), ruling out $c_{s}^{max} < c / 3$ at high significance. Our constraints on the maximum neutron star mass strengthen the case for neutron star-neutron star mergers as the primary source of short gamma-ray bursts.
Comments:
16 pages, 10 figures, updated to MNRAS accepted version (24 Apr 2018)
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
1709.07889 [pdf]
MNRAS(2018)·278 citations
07
[Submitted on 23 Sept 2017] (cross-list from hep-ph)
Thermal vorticity production in relativistic dissipative fluids
Yang-guang Yang🇨🇳 · Shi Pu🇯🇵
We have computed the circulation integrations of thermal vorticity with and without charged currents in dissipative fluids. We find that the relativistic Kelvin circulation theorem will be modified by the dissipative effects, therefore, the circulation integrations of thermal vorticity may not be conserved during the fluid evolution.
Comments:
Presented by S. Pu at Critical Point and Onset of Deconfinement (CPOD), Wroclaw, Poland, May 30 - June 4, 2016
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1709.08002 [pdf]
Acta Phys.Polon.Supp.(2017)·2 citations
08
[Submitted on 24 Sept 2017] (cross-list from hep-ph)
Regge phenomenology of photoproduction of $π^{-} Δ^{++}$ and scaling with saturation of trajectory
Byung-Geel Yu🇰🇷 · Kook-Jin Kong🇰🇷
In this work we investigate the reaction $γ p \to π^{-} Δ^{++}$ in the Reggeized model for $π (138) + ρ (775) + a_{2} (1320)$ exchanges in the $t$ -channel. For a convergence of the reaction cross section at high energies the minimal forms of proton and $Δ^{++}$ exchanges are introduced in the direct and crossed channels for gauge invariance of $π$ Regge-pole exchange. The role of spin-2 tensor meson $a_{2}$ is found to be crucial to agree with existing data at high energies. Electromagnetic multipoles of $Δ^{++}$ baryon are analyzed in the $Δ$ resonance region. Based on the constituents counting rule the scaled differential cross section at $E_{γ} = 4$ GeV is reproduced with the Regge trajectory saturated at large momentum transfer $- t$ .
Comments:
5 pages 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1709.08175 [pdf]
Phys.Part.Nucl.Lett.(2018)·2 citations
09
[Submitted on 24 Sept 2017] (cross-list from hep-th)
Characteristics of Chiral Anomaly in View of Various Applications
Kazuo Fujikawa🇯🇵
In view of the recent applications of chiral anomaly to various fields beyond particle physics, we discuss some basic aspects of chiral anomaly which may help deepen our understanding of chiral anomaly in particle physics also. It is first shown that Berry's phase (and its generalization) for the Weyl model $H = v_{F} σ \cdot p (t)$ assumes a monopole form at the exact adiabatic limit but deviates from it off the adiabatic limit and vanishes in the high frequency limit of the Fourier transform of $p (t)$ for bounded $∣ p (t) ∣$ . An effective action, which is consistent with the non-adiabatic limit of Berry's phase, combined with the Bjorken-Johnson-Low prescription gives normal equal-time space-time commutators and no chiral anomaly. In contrast, an effective action with a monopole at the origin of the momentum space, which describes Berry's phase in the precise adiabatic limit but fails off the adiabatic limit, gives anomalous space-time commutators and a covariant anomaly to the gauge current. We regard this anomaly as an artifact of the postulated monopole and not a consequence of Berry's phase. As for the recent application of the chiral anomaly to the description of effective Weyl fermions in condensed matter and nuclear physics, which is closely related to the formulation of lattice chiral fermions, we point out that the chiral anomaly for each species doubler separately vanishes for a finite lattice spacing, contrary to the common assumption. Instead a general form of pair creation associated with the spectral flow for the Dirac sea with finite depth takes place. This view is supported by the Ginsparg-Wilson fermion, which defines a single Weyl fermion without doublers on the lattice and gives a well-defined index (anomaly) even for a finite lattice spacing.
Comments:
14 pages. Some explanations are added. This version is to be published in PRD
Subjects:
High Energy Physics — Theory (hep-th); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Nuclear Theory (nucl-th)
arXiv:
1709.08181 [pdf]
PRD(2018)·12 citations
10
[Submitted on 24 Sept 2017] (cross-list from hep-lat)
Three-body Unitarity in the Finite Volume
M. Mai🇺🇸 · M. Döring🇺🇸
The physical interpretation of lattice QCD simulations, performed in a small volume, requires an extrapolation to the infinite volume. A method is proposed to perform such an extrapolation for three interacting particles at energies above threshold. For this, a recently formulated relativistic $3 \to 3$ amplitude based on the isobar formulation is adapted to the finite volume. The guiding principle is two- and three-body unitarity that imposes the imaginary parts of the amplitude in the infinite volume. In turn, these imaginary parts dictate the leading power-law finite-volume effects. It is demonstrated that finite-volume poles arising from the singular interaction, from the external two-body sub-amplitudes, and from the disconnected topology cancel exactly leaving only the genuine three-body eigenvalues. The corresponding quantization condition is derived for the case of three identical scalar-isoscalar particles and its numerical implementation is demonstrated.
Comments:
9 pages, 3 figures
Subjects:
High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1709.08222 [pdf]
EPJA(2017)·231 citations
11
[Submitted on 24 Sept 2017] (cross-list from quant-ph)
Ground States via Spectral Combing on a Quantum Computer
David B. Kaplan🇺🇸 · Natalie Klco🇺🇸 · Alessandro Roggero🇺🇸
A new method is proposed for determining the ground state wave function of a quantum many-body system on a quantum computer, without requiring an initial trial wave function that has good overlap with the true ground state. The technique of Spectral Combing involves entangling an arbitrary initial wave function with a set of auxiliary qubits governed by a time dependent Hamiltonian, resonantly transferring energy out of the initial state through a plethora of avoided level crossings into the auxiliary system. The number of avoided level crossings grows exponentially with the number of qubits required to represent the Hamiltonian, so that the efficiency of the algorithm does not rely on any particular energy gap being large. We give an explicit construction of the quantum gates required for the realization of this procedure and explore the results of classical simulations of the algorithm on a small quantum computer with up to 8 qubits. We show that for certain systems and comparable results, Spectral Combing requires fewer quantum gates to realize than the Quantum Adiabatic Algorithm.
Subjects:
Quantum Physics (quant-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1709.08250 [pdf]
47 citations
12
[Submitted on 25 Sept 2017] (cross-list from hep-ph)
General structure of fermion two-point function and its spectral representation in a hot magnetised medium
Aritra Das🇮🇳 · Aritra Bandyopadhyay🇮🇳 · Pradip K. Roy🇮🇳 · Munshi G. Mustafa🇮🇳
We have systematically constructed the general structure of the fermion self-energy and the effective quark propagator in presence of a nontrivial background like hot magnetised medium. This is applicable to both QED and QCD. The hard thermal loop approximation has been used for the heat bath. We have also examined transformation properties of the effective fermion propagator under some of the discrete symmetries of the system. Using the effective fermion propagator we have analysed the fermion dispersion spectra in a hot magnetised medium along with the spinor for each fermion mode obtained by solving the modified Dirac equation. The fermion spectra is found to reflect the discrete symmetries of the two-point functions. We note that for a chirally symmetric theory the degenerate left and right handed chiral modes in vacuum or in a heat bath get separated and become asymmetric in presence of magnetic field without disturbing the chiral invariance. The obtained general structure of the two-point functions is verified by computing the three-point function, which agrees with the existing results in one-loop order. Finally, we have computed explicitly the spectral representation of the two-point functions which would be very important to study the spectral properties of the hot magnetised medium corresponding to QED and QCD with background magnetic field.
Comments:
31 pages, 7 figures; Version accepted in Phys. Rev. D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1709.08365 [pdf]
PRD(2018)·31 citations
13
[Submitted on 25 Sept 2017] (cross-list from hep-th)
Quenching the CME via the gravitational anomaly and holography
Karl Landsteiner🇪🇸 · Esperanza Lopez🇪🇸 · Guillermo Milans del Bosch🇪🇸
In the presence of a gravitational contribution to the chiral anomaly, the chiral magnetic effect induces an energy current proportional to the square of the temperature in equilibrium. In holography the thermal state corresponds to a black hole. We numerically study holographic quenches in which a planar shell of scalar matter falls into a black hole and rises its temperature. During the process the momentum density (energy current) is conserved. The energy current has two components, a non-dissipative one induced by the anomaly and a dissipative flow component. The dissipative component can be measured via the drag it asserts on an additional auxiliary color charge. Our results indicate strong suppression very far from equilibrium.
Comments:
5 pages, 6 figures
Subjects:
High Energy Physics — Theory (hep-th); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1709.08384 [pdf]
PRL(2018)·18 citations
14
[Submitted on 25 Sept 2017] (cross-list from hep-ph)
Standard convolution description of deuteron tensor spin structure
W. Cosyn🇧🇪 · Yu-Bing Dong🇨🇳 · S. Kumano🇯🇵 · M. Sargsian🇺🇸
Spin-1 hadrons have additional structure functions not present for spin 1/2 hadrons. These could probe novel aspects of hadron structure and QCD dynamics. For the deuteron, the tensor structure function $b_{1}$ inherently mixes quark and nuclear degrees of freedom. These proceedings discuss two standard convolution models applied to calculations of the deuteron $b_{1}$ structure functions. We find large differences with the existing HERMES data and other convolution model calculations. This leaves room for non-standard contributions to $b_{1}$ in the deuteron. We also discuss the influence of higher twist nuclear effects in the model calculations and data extraction at kinematics covered in HERMES and Jefferson Lab.
Comments:
Proceedings of 25th International Workshop on Deep Inelastic Scattering and Related Topics, 3-7 April 2017 University of Birmingham
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1709.08400 [pdf]
PoS(2018)·0 citations
15
[Submitted on 25 Sept 2017] (cross-list from hep-ph)
Dynamical vs geometric anisotropy in relativistic heavy-ion collisions: which one prevails?
L.V. Bravina🇷🇺 · I.P. Lokhtin🇷🇺 · L.V. Malinina🇷🇺 · S.V. Petrushanko🇷🇺 · A.M. Snigirev🇷🇺 · E.E. Zabrodin🇷🇺
We study the influence of geometric and dynamical anisotropies on the development of flow harmonics and, simultaneously, on the second- and third-order oscillations of femtoscopy radii. The analysis is done within the Monte Carlo event generator HYDJET++, which was extended to dynamical triangular deformations. It is shown that the merely geometric anisotropy provides the results which anticorrelate with the experimental observations of either $v_{2}$ (or $v_{3}$ ) or second-order (or third-order) oscillations of the femtoscopy radii. Decays of resonances significantly increase the emitting areas but do not change the phases of the radii oscillations. In contrast to the spatial deformations, the dynamical anisotropy alone provides the correct qualitative description of the flow and the femtoscopy observables simultaneously. However, one needs both types of the anisotropy to match quantitatively the experimental data.
Comments:
minor corrections, published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1709.08602 [pdf]
EPJA(2017)·14 citations

Affiliations

first authorsco-authorsvia INSPIRE