Nuclear Theory·nucl-th

Wednesday·January 23, 2019

23 papers—10 primary·13 cross-listed

01
[Submitted on 18 Jan 2019]
Heavy-Flavor Theory at "Hard and Electromagnetic Probes 2018"
Ralf Rapp🇺🇸
An overview is given of the theoretical developments on heavy quarks and quarkonia in heavy-ion collisions as reported at the "Hard and EM Probes 2018" conference. Specifically, we address progress in the understanding of heavy-flavor diffusion and its hadronization, quarkonium transport and the extraction of quarkonium melting temperatures, energy loss of heavy quarks at high momentum, and their rescattering in small colliding systems.
Comments:
8 pages, 1 pdf figure, Proceedings of "Hard Probes 2018" conference, Aix-Les-Bains (France), Sept. 30 - Oct. 05
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1901.06440 [pdf]
PoS(2019)·3 citations
02
[Submitted on 20 Jan 2019]
Role of pair-vibrational correlations in forming the odd-even mass difference
K. Neergård · I. Bentley
In the random-phase-approximation-amended (RPA-amended) Nilsson-Strutinskij method of calculating nuclear binding energies, the conventional shell correction terms derived from the independent-nucleon model and the Bardeen-Cooper-Schrieffer pairing theory are supplemented by a term which accounts for the pair-vibrational correlation energy. This term is derived by means of the RPA from a pairing Hamiltonian which includes a neutron-proton pairing interaction. The method was used previously in studies of the pattern of binding energies of nuclei with approximately equal numbers $N$ and $Z$ of neutrons and protons and even mass number $A = N + Z$ . Here it is applied to odd- $A$ nuclei. Three sets of such nuclei are considered: (i) The sequence of nuclei with $Z = N - 1$ and $25 \leq A \leq 99$ . (ii) The odd- $A$ isotopes of In, Sn, and Sb with $46 \leq N \leq 92$ . (iii) The odd- $A$ isotopes of Sr, Y, Zr, Nb, and Mo with $60 \leq N \leq 64$ . The RPA correction is found to contribute significantly to the calculated odd-even mass differences, particularly in the light nuclei. In the upper $s d$ shell this correction accounts for almost the entire odd-even mass difference for odd $Z$ and about half of it for odd $N$ . The size and sign of the RPA contribution varies, which is explained qualitatively in terms of a closed expression for a smooth RPA counter term.
Comments:
Deformations that were missing in the previous table II have been included
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1901.06655 [pdf]
PRC(2019)·5 citations
03
[Submitted on 21 Jan 2019]
Consistency Examinations of Calculations of Nuclear Matrix Elements of Double- $β$ Decay by QRPA
J. Terasaki🇨🇿
The neutrinoless double- $β$ decay is a hypothetical rare nuclear decay, which can be used for determining the neutrino-mass scale. The scheme to use this decay for determining the neutrino-mass scale is one of few limited methods possible to determine that. Nuclear matrix element of this decay is an important input to this method, and this matrix element cannot be determined by experiment. I examine the validity of the transition density used for calculating the nuclear matrix element by comparing the experimental data and my calculated result of the charge-change strength functions of $^{48}$ Ca and $^{48}$ Ti. The nuclear wave functions are obtained by the quasiparticle random-phase approximation. A new idea is proposed on the transition operator for this strength function, and the data of those nuclei are reproduced well consistently. Reduced half-life of a few nuclei to the neutrinoless double- $β$ decay are shown.
Comments:
9pages, proceedings of the 37th International Workshop on Nuclear Theory, June 24 $-$ June 30, 2018, the Rila Mountains, Bulgaria
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex)
arXiv:
1901.06841 [pdf]
Nucl.Theor.(2018)·0 citations
04
[Submitted on 21 Jan 2019]
Determination of Strength of Isoscalar Pairing Interaction by a Mathematical Identity in QRPA
J. Terasaki🇨🇿
I propose a new method to determine the strength of the isoscalar proton-neutron pairing interaction by a mathematical identity derived in the quasiparticle random-phase approximation. This method is applied for a few nuclei possibly having the neutrinoless double- $β$ decay. Reduced half-life, the theoretical quantity necessary for determining the effective neutrino mass, is calculated for $^{48}$ Ca.
Comments:
5 pages, proceedings of Zakopane Conference on Nuclear Physics "Extreme of the Nuclear Landscape", August 26 $-$ September 2, 2018, Zakopane, Poland
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1901.06846 [pdf]
0 citations
05
[Submitted on 21 Jan 2019]
Paramagnetic squeezing of a uniformly expanding quark-gluon plasma in and out of equilibrium
N. Sadooghi🇮🇷 · S.M.A. Tabatabaee🇮🇷
The plasma of quarks and gluons created in ultrarelativistic heavy-ion collisions turns out to be paramagnetic. In the presence of a background magnetic field, this paramagnetism thus leads to a pressure anisotropy, similar to anisotropies appearing in a viscous fluid. In the present paper, we use this analogy, and develop a framework similar to anisotropic hydrodynamics, to take the pressure anisotropy caused, in particular, by the nonvanishing magnetization of a plasma of quarks and gluons into account. We consider the first two moments of the classical Boltzmann equation in the presence of an electromagnetic source in the relaxation-time approximation, and derive a set of coupled differential equations for the anisotropy parameter $ξ_{0}$ and the effective temperature $λ_{0}$ of an ideal fluid with nonvanishing magnetization. We also extend this method to a dissipative fluid with finite magnetization in the presence of a strong and dynamical magnetic field. We present a systematic method leading to the one-particle distribution function of this magnetized dissipative medium in a first-order derivative expansion, and arrive at analytical expressions for the shear and bulk viscosities in terms of the anisotropy parameter $ξ$ and effective temperature $λ$ . We then solve the corresponding differential equations for $(ξ_{0}, λ_{0})$ and $(ξ, λ)$ numerically, and determine, in this way, the proper time and temperature dependence of the energy density, directional pressures, speed of sound, and the magnetic susceptibility of a longitudinally expanding magnetized quark-gluon plasma in and out of equilibrium.
Comments:
V1:23 pages, 16 figures; V2: Typos corrected, version accepted for publication in PRD (2019)
Subjects:
Nuclear Theory (nucl-th); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1901.06928 [pdf]
PRD(2019)·8 citations
06
[Submitted on 21 Jan 2019]
Symmetry restoration in mean-field approaches
J.A. Sheikh🇮🇳 · J. Dobaczewski🇬🇧 · P. Ring🇩🇪 · L. M. Robledo🇪🇸 · C. Yannouleas🇺🇸
The mean-field approximation based on effective interactions or density functionals plays a pivotal role in the description of finite quantum many-body systems that are too large to be treated by ab initio methods. Some examples are strongly interacting medium and heavy mass atomic nuclei and mesoscopic condensed matter systems. In this approach, the linear Schrodinger equation for the exact many-body wave function is mapped onto a non-linear density-dependent one-body potential problem. This approximation, not only provides computationally very simple solutions even for systems with many particles, but due to the non-linearity, it also allows for obtaining solutions that break essential symmetries of the system, often connected with phase transitions. In this way, additional correlations are subsumed in the system. However, the mean-field approach suffers from the drawback that the corresponding wave functions do not have sharp quantum numbers and, therefore, many results cannot be compared directly with experimental data. In this article, we discuss general group-theory techniques to restore the broken symmetries, and provide detailed expressions on the restoration of translational, rotational, spin, isospin, parity and gauge symmetries, where the latter corresponds to the restoration of the particle number. In order to avoid the numerical complexity of exact projection techniques, various approximation methods available in the literature are examined. Applications of the projection methods are presented for simple nuclear models, realistic calculations in relatively small configuration spaces, nuclear energy density functional theory, as well as in other mesoscopic systems. Further, unresolved problems in the application of the symmetry restoration methods to the energy density functional theories are highlighted in the present work.
Comments:
145 pages, 23 figures, 456 references, accepted for publication in Journal of Physics G
Subjects:
Nuclear Theory (nucl-th); cond-mat.other (cond-mat.other); Nuclear Experiment (nucl-ex)
arXiv:
1901.06992 [pdf]
J.Phys.G(2021)·144 citations
07
[Submitted on 21 Jan 2019]
Centrality dependence of the direct photon multiplicity in heavy ion collisions
Charles Gale🇨🇦 · Sangyong Jeon🇨🇦 · Scott McDonald🇨🇦 · Jean-François Paquet🇺🇸 · Chun Shen🇺🇸
Measurements indicate that the centrality dependence of the direct photon multiplicity scales approximately with the number of binary nucleon collisions. Importantly, these same measurements suggest that this scaling does not depend on the cutoff used to define the photon multiplicity. In this work we provide a theoretical perspective on these observations. We emphasize the importance of stronger experimental constraints, in particular for the cutoff independence of the centrality scaling. We highlight the importance of revisiting theoretical studies of jet-medium photons and of medium-modified prompt photons to clarify their contribution to the direct photon multiplicity, as well as the magnitude and direction of their momentum anisotropy.
Comments:
Contribution to Hard Probes 2018 proceedings. 4 pages
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1901.07019 [pdf]
PoS(2019)·3 citations
08
[Submitted on 21 Jan 2019]
Parton energy loss in the reformulated weakly-coupled kinetic approach
Tianyu Dai🇺🇸 · Steffen A. Bass🇺🇸 · Jean-François Paquet🇺🇸 · Derek Teaney🇺🇸
Interactions between hard partons and the quark-gluon plasma range from frequent soft interactions to rare hard scatterings. The larger number of soft interactions makes possible an effective stochastic description of parton-plasma interactions in terms of drag and diffusion transport coefficients. In this work, we present a numerical implementation that builds upon this systematic division between soft and hard parton-plasma interactions. We study the dependence of the single parton distribution on the cutoff between soft and hard parton-plasma interactions, both for small and phenomenological values of the strong coupling constant.
Comments:
5 pages, 2 figures, contribution to the proceedings of Hard Probes 2018: International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1901.07022 [pdf]
PoS(2019)·1 citation
09
[Submitted on 21 Jan 2019]
Nuclear coalescence from correlation functions
Kfir Blum🇮🇱 · Masahiro Takimoto🇮🇱
We derive a simple formula relating the cross section for light cluster production (defined via a coalescence factor) to the two-proton correlation function measured in heavy-ion collisions. The formula generalises earlier coalescence-correlation relations found by Scheibl & Heinz and by Mrowczynski for Gaussian source models. It motivates joint experimental analyses of Hanbury Brown-Twiss (HBT) and cluster yield measurements in existing and future data sets.
Comments:
10 pages, 4 figures. v2: some clarifications. A missing (2\pi)^3 normalization factor, relating diff cross sec to density matrix traces, is corrected in Secs.II.A and II.B. It does not affect any of the results
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1901.07088 [pdf]
PRC(2019)·71 citations
10
[Submitted on 18 Jan 2019]
Resonance states 0+ of the Boron isotope B8 from the Jost-matrix analysis of experimental data
S.A. Rakityansky · S.N. Ershov · T.J. Tshipi
The available R-matrix parametrization of experimental data on the excitation functions for the elastic and inelastic p-Be7 scattering at the collision energies up to 3.4 MeV is used to generate the corresponding partial-wave cross sections in the states with J^pi=0+. Thus obtained data are considered as experimental partial cross sections and are fitted using the semi-analytic two-channel Jost matrix with proper analytic structure and some adjustable parameters. Then the spectral points are sought as zeros of the Jost matrix determinant (which correspond to the S-matrix poles) at complex energies. The correct analytic structure makes it possible to calculate the fitted Jost matrix on any sheet of the Riemann surface whose topology involves not only the square-root but also the logarithmic branching caused by the Coulomb interaction. In this way, two overlapping 0+ resonances at the excitation energies ~1.79 MeV and ~1.96 MeV have been found.
Comments:
27 pages, 11 figures. arXiv admin note: text overlap with arXiv:1807.00209
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1901.07391 [pdf]
IJMPE(2019)·5 citations
11
[Submitted on 18 Jan 2019] (cross-list from hep-ph)
The Jet Shape at NLL $^{'}$
Pedro Cal🇳🇱 · Felix Ringer🇺🇸 · Wouter J. Waalewijn🇳🇱
The jet shape is the fraction of the jet energy within a cone $r$ centered on the jet axis. We calculate the jet shape distribution at next-to-leading logarithmic accuracy plus next-to-leading order (NLL $^{'}$ ), accounting for logarithms of both the jet radius $R$ and the ratio $r / R$ . This is the first phenomenological study that takes the recoil of the jet axis due to soft radiation into account, which is needed to reach this accuracy, but complicates the calculation of collinear radiation and requires the treatment of rapidity logarithms and non-global logarithms. We present numerical results, finding good agreement with ATLAS and CMS measurements of the jet shape in an inclusive jet sample, $pp \to jet + X$ , for different kinematic bins. The effect of the underlying event and hadronization are included using a simple one-parameter model, since they are not part of our perturbative calculation.
Comments:
36 pages, 14 figures, v2: extended discussion of non-global logarithms, journal version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1901.06389 [pdf]
JHEP(2019)·37 citations
12
[Submitted on 20 Jan 2019] (cross-list from hep-th)
Fate of spin polarization in a relativistic fluid: An entropy-current analysis
Koichi Hattori🇨🇳 · Masaru Hongo🇯🇵 · Xu-Guang Huang🇨🇳 · Mamoru Matsuo🇨🇳 · Hidetoshi Taya🇨🇳
We derive relativistic hydrodynamic equations with a dynamical spin degree of freedom on the basis of an entropy-current analysis. The first and second laws of local thermodynamics constrain possible structures of the constitutive relations including a spin current and the antisymmetric part of the (canonical) energy-momentum tensor. Solving the obtained hydrodynamic equations within the linear-mode analysis, we find spin-diffusion modes, indicating that spin density is damped out after a characteristic time scale controlled by transport coefficients introduced in the antisymmetric part of the energy-momentum tensor in the entropy-current analysis. This is a consequence of mutual convertibility between spin and orbital angular momentum.
Comments:
7 pages
Subjects:
High Energy Physics — Theory (hep-th); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1901.06615 [pdf]
PLB(2019)·230 citations
13
[Submitted on 20 Jan 2019] (cross-list from physics.hist-ph)
John Archibald Wheeler: A Biographical Memoir
Kip S. Thorne
John Archibald Wheeler was a theoretical physicist who worked on both down-to-earth projects and highly speculative ideas, and always emphasized the importance of experiment and observation, even when speculating wildly. His research and insights had large impacts on nuclear and particle physics, the design of nuclear weapons, general relativity and relativistic astrophysics, and quantum gravity and quantum information. But his greatest impacts were through the students, postdocs, and mature physicists whom he educated and inspired. He was guided by what he called the principle of radical conservatism, inspired by Niels Bohr: base your research on well established physical laws (be conservative), but push them into the most extreme conceivable domains (be radical). He often pushed far beyond the boundaries of well understood physics, speculating in prescient ways that inspired future generations of physicists. After completing his PhD with Karl Herzfeld at Johns Hopkins University (1933), Wheeler embarked on a postdoctoral year with Gregory Breit at NYU and another with Niels Bohr in Copenhagen. He then moved to a three-year assistant professorship at the University of North Carolina (1935-37), followed by a 40 year professorial career at Princeton University (1937-1976) and then ten years as a professor at the University of Texas, Austin (1976-1987). He returned to Princeton in retirement but remained actively and intensely engaged with physics right up to his death at age 96.
Comments:
This memoir is being published in the Biographical Memoir Series of the US National Academy of Sciences and also that of the Royal Society, in early 2019
Subjects:
History and Philosophy of Physics (physics.hist-ph); 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:
1901.06623 [pdf]
7 citations
14
[Submitted on 20 Jan 2019] (cross-list from gr-qc)
Causality of the Einstein-Israel-Stewart Theory with Bulk Viscosity
Fabio S. Bemfica (Rio Grande do Norte U.)🇧🇷 · Marcelo M. Disconzi (Vanderbilt U.)🇺🇸 · Jorge Noronha (Sao Paulo U.)🇧🇷
We prove that Einstein's equations coupled to equations of Israel-Stewart-type, describing the dynamics of a relativistic fluid with bulk viscosity and nonzero baryon charge (without shear viscosity or baryon diffusion) dynamically coupled to gravity, are causal in the full nonlinear regime. We also show that these equations can be written as a first-order symmetric hyperbolic system, implying local existence and uniqueness of solutions to the equations of motion. We use an arbitrary equation of state and do not make any simplifying symmetry or near-equilibrium assumption, requiring only physically natural conditions on the fields. These results pave the way for the inclusion of bulk viscosity effects in simulations of gravitational-wave signals coming from neutron star mergers.
Comments:
10 pages (including appendix), version published in Physical Review Letters
Subjects:
General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th)
arXiv:
1901.06701 [pdf]
PRL(2019)·124 citations
15
[Submitted on 21 Jan 2019] (cross-list from nucl-ex)
Higher order Symmetric Cumulants
Cindy Mordasini🇩🇪 · Ante Bilandzic🇩🇪 · Deniz Karakoç🇩🇪 · Seyed Farid Taghavi🇩🇪
We present the generalization of recently introduced observables for the studies of correlated fluctuations of different anisotropic flow amplitudes, dubbed Symmetric Cumulants. We introduce a new set of higher order observables and outline a unique way how the genuine multi-harmonic correlations can be extracted from multi-particle azimuthal correlators. We argue that correlations among flow amplitudes can be studied reliably with the general mathematical formalism of cumulants only if that formalism is applied directly on the flow amplitudes. We have tested all the desired properties of new observables with the carefully designed Toy Monte Carlo studies. By using the realistic iEBE-VISHNU model, we have demonstrated that their measurements are feasible and we have provided the predictions for the centrality dependence in Pb--Pb collisions at LHC energies. A separate study was performed for their values in the coordinate space. The new observables contain information which is inaccessible to individual flow amplitudes and correlated fluctuations of only two flow amplitudes, and therefore they provide further and independent constraints for the initial conditions and the properties of Quark-Gluon Plasma in high-energy nuclear collisions.
Comments:
30 pages, 12 figures. Major revision. This version was accepted for publication in Physical Review C
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1901.06968 [pdf]
PRC(2020)·42 citations
16
[Submitted on 21 Jan 2019] (cross-list from hep-lat)
Implementing the three-particle quantization condition including higher partial waves
Tyler D. Blanton🇺🇸 · Fernando Romero-López🇪🇸 · Stephen R. Sharpe🇺🇸
We present an implementation of the relativistic three-particle quantization condition including both $s$ - and $d$ -wave two-particle channels. For this, we develop a systematic expansion about threshold of the three-particle divergence-free K matrix, $K_{df, 3}$ , which is a generalization of the effective range expansion of the two-particle K matrix, $K_{2}$ . Relativistic invariance plays an important role in this expansion. We find that $d$ -wave two-particle channels enter first at quadratic order. We explain how to implement the resulting multichannel quantization condition, and present several examples of its application. We derive the leading dependence of the threshold three-particle state on the two-particle $d$ -wave scattering amplitude, and use this to test our implementation. We show how strong two-particle $d$ -wave interactions can lead to significant effects on the finite-volume three-particle spectrum, including the possibility of a generalized three-particle Efimov-like bound state. We also explore the application to the $3 π^{+}$ system, which is accessible to lattice QCD simulations, where we study the sensitivity of the spectrum to the components of $K_{df, 3}$ . Finally, we investigate the circumstances under which the quantization condition has unphysical solutions.
Comments:
57 pages, 12 figures, 3 tables (v2: Made minor clarifications, updated a reference, fixed typos)
Subjects:
High Energy Physics — Lattice (hep-lat); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
1901.07095 [pdf]
JHEP(2019)·119 citations
17
[Submitted on 22 Jan 2019] (cross-list from hep-ph)
Dynamical analysis of the $X$ resonance contributions to the decay $J / ψ \to γ X \to γ ϕϕ$
A.A. Kozhevnikov🇷🇺
The dynamics of the $J^{P C} = 0^{-+}$ , $0^{++}$ , and $2^{++}$ resonance contributions to the decay $J / ψ \to γ X (J^{P C}) \to γ ϕϕ$ is analysed using the data obtained by BESIII collaboration. The effective coupling constants parameterising invariant amplitudes of the transitions $J / ψ \to γ X (J^{P C})$ and $X (J^{P C}) \to ϕϕ$ and masses of $X (J^{P C})$ resonances are found from the fits. They are used for evaluation of the branching fractions $B_{X (J^{P C}) \to ϕϕ}$ , relative branching fractions $B_{J / ψ \to γ X (J^{P C}) \to γ ϕϕ}$ , and for obtaining the photon angular distributions.
Comments:
11 pages, 8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1901.07177 [pdf]
PRD(2019)·7 citations
18
[Submitted on 22 Jan 2019] (cross-list from hep-lat)
Recent Progress on the QCD Phase Diagram
Sayantan Sharma🇮🇳
Recent progress and the latest results on the bulk thermodynamic properties of QCD matter from lattice are reviewed. In particular, I will stress upon the fact that lattice techniques are now entering into precision era where they can provide us with new insights on even the microscopic degrees of freedom in different phases of QCD. I will discuss some instances, from the recent studies of topological fluctuations and screening masses. The progress towards understanding the effects of anomalous $U_{A} (1)$ symmetry on the chiral crossover transition and transport properties of QCD matter will also be discussed.
Comments:
16 pages, 16 figures. Proceedings of the 36th Annual International Symposium on Lattice Field Theory - LATTICE2018, Michigan State University, v2: Minor additions, typos corrected
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1901.07190 [pdf]
PoS(2019)·18 citations
19
[Submitted on 22 Jan 2019] (cross-list from hep-ph)
Fate of the doubly heavy spin $- 3/2$ baryons in a dense medium
N. Er🇹🇷 · K. Azizi🇹🇷
We investigate the behavior of the doubly heavy spin $- 3/2$ baryons in cold nuclear matter. In particular, we study the variations of the spectroscopic parameters of the ground state $Ξ_{Q Q^{'}}^{*}$ and $Ω_{Q Q^{'}}^{*}$ particles, with $Q$ and $Q^{'}$ being $b$ or $c$ quark, with respect to the changes in the density of the nuclear medium. We find the shifts on the parameters under question at saturation medium density compared to their vacuum values. It is observed that the parameters of the $Ξ_{Q Q^{'}}^{*}$ states containing two heavy quarks and one up or down quark are affected by the medium, considerably. The parameters of the $Ω_{Q Q^{'}}^{*}$ states containing two heavy quarks and one strange quark, however, do not show any sensitivity to the density of the cold nuclear medium. We also discuss the variations of the vector self-energy at each channel with respect to the changes in the density. The negative shifts in the mass of $Ξ_{Q Q^{'}}^{*}$ states due to nucleons in the medium can be used to study the doubly heavy baryons' interactions with the nucleons. The results obtained can also be used in analyses of the results of the future in-medium experiments.
Comments:
24 Pages, 5 Figures and 3 Tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1901.07399 [pdf]
PRD(2019)·5 citations
20
[Submitted on 18 Jan 2019] (cross-list from hep-ph)
$Φ$ and $J /Ψ$ Mesons in Cold Nuclear Matter
J. J. Cobos-Martínez🇲🇽 · K. Tsushima🇧🇷 · G. Krein🇧🇷 · A. W. Thomas🇦🇺
We present $Φ$ - and $J /Ψ$ --nuclear bound state energies and absorption widths for some selected nuclei, using potentials in the local density approximation computed from an effective Lagrangian approach combined with the quark-meson coupling model. Our results suggest that these mesons should form bound states with all the nuclei considered provided that these mesons are produced in nearly recoilless kinematics.
Comments:
Contribution to the Proceedings of 8th International Conference on Quarks and Nuclear Physics (QNP2018), November 13-17, 2018, Tsukuba, Japan. arXiv admin note: text overlap with arXiv:1711.09895
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1901.07404 [pdf]
JPS Conf.Proc.(2019)·3 citations
21
[Submitted on 22 Jan 2019] (cross-list from hep-ph)
Soft modifications to jet fragmentation in high energy proton-proton collisions
Christian Bierlich🇩🇰
The discovery of collectivity in proton-proton collisions, is one of the most puzzling outcomes from the two first runs at LHC, as it points to the possibility of creation of a Quark-Gluon Plasma, earlier believed to only be created in heavy ion collisions. One key observation from heavy ion collisions is still not observed in proton-proton, namely jet-quenching. In this letter it is shown how a model capable of describing soft collective features of proton-proton collisions, also predicts modifications to jet fragmentation properties. With this starting point, several new observables suited for the present and future hunt for jet quenching in small collision systems are proposed.
Comments:
7 pages, 7 figures, 1 table, updated to the published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1901.07447 [pdf]
PLB(2019)·18 citations
22
[Submitted on 22 Jan 2019] (cross-list from hep-ph)
Orbital Angular Momentum at Small $x$
Yuri V. Kovchegov🇺🇸
We determine the small Bjorken $x$ asymptotics of the quark and gluon orbital angular momentum (OAM) distributions in the proton in the double-logarithmic approximation (DLA), which resums powers of $α_{s} ln^{2} (1/ x)$ with $α_{s}$ the strong coupling constant. Starting with the operator definitions for the quark and gluon OAM, we simplify them at small $x$ , relating them, respectively, to the polarized dipole amplitudes for the quark and gluon helicities defined in our earlier works. Using the small- $x$ evolution equations derived for these polarized dipole amplitudes earlier we arrive at the following small- $x$ asymptotics of the quark and gluon OAM distributions in the large- $N_{c}$ limit: \begin{align} L_{q + \bar{q}} (x, Q^2) = - \Delta \Sigma (x, Q^2) \sim \left(\frac{1}{x}\right)^{\frac{4}{\sqrt{3}} \, \sqrt{\frac{\alpha_s \, N_c}{2 \pi}} }, \ \ \ \ \ L_G (x, Q^2) \sim \Delta G (x, Q^2) \sim \left(\frac{1}{x}\right)^{\frac{13}{4 \sqrt{3}} \, \sqrt{\frac{\alpha_s \, N_c}{2 \pi}}} . \end{align}
Comments:
27 pages
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1901.07453 [pdf]
JHEP(2019)·61 citations
23
[Submitted on 22 Jan 2019] (cross-list from hep-lat)
Lattice QCD determination of neutron-antineutron matrix elements with physical quark masses
Enrico Rinaldi🇺🇸 · Sergey Syritsyn🇺🇸 · Michael L. Wagman🇺🇸 · Michael I. Buchoff🇺🇸 · Chris Schroeder🇺🇸 · Joseph Wasem🇺🇸
Matrix elements of six-quark operators are needed to extract new physics constraints from experimental searches for neutron-antineutron oscillations. This work presents in detail the first lattice quantum chromodynamics calculations of the necessary neutron-antineutron transition matrix elements including calculation methods and discussions of systematic uncertainties. Implications of isospin and chiral symmetry on the matrix elements, power counting in the isospin limit, and renormalization of a chiral basis of six-quark operators are discussed. Calculations are performed with a chiral-symmetric discretization of the quark action and physical light quark masses in order to avoid the need for chiral extrapolation. Non-perturbative renormalization is performed, including a study of lattice cutoff effects. Excited-state effects are studied using two nucleon operators and multiple values of source-sink separation. Results for the dominant matrix elements are found to be significantly larger compared to previous results from the MIT bag model. Future calculations are needed to fully account for systematic uncertainties associated with discretization and finite-volume effects but are not expected to significantly affect this conclusion.
Comments:
29 pages, 30 figures. Matches published version
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1901.07519 [pdf]
PRD(2019)·74 citations

Affiliations

first authorsco-authorsvia INSPIRE