Nuclear Theory·nucl-th

Tuesday·November 7, 2017

22 papers—8 primary·14 cross-listed

09
Efficient operators for studying higher partial waves
Jia-jun Wu🇦🇺 · Waseem Kamleh🇦🇺 · Derek B. Leinweber🇦🇺 · Gerrit Schierholz🇩🇪 · Ross D. Young🇦🇺 · James M. Zanotti🇦🇺
An extended multi-hadron operator is developed to extract the spectra of irreducible representations in the finite volume. The irreducible representations of the cubic group are projected using a coordinate-space operator. The correlation function of this operator is computationally efficient to extract lattice spectra. In particular, this new formulation only requires propagator inversions from two distinct locations, at fixed physical separation. We perform a proof-of-principle study on a $2 4^{3} \times 48$ lattice volume with $m_{π} \approx 900$ ~MeV by isolating the spectra of $A_{1}^{+}$ , $E^{+}$ and $T_{2}^{+}$ of the $π π$ system with isospin-2 in the rest frame.
↳ hep-lathep-phnucl-thEPJ Web Conf.(2018)·0 citations
10
Remarks on the hidden color components in multi-quark study
Fan Wang🇨🇳 · Jialun Ping🇨🇳 · Hongxia Huang🇨🇳
Problems related to the application of hidden color components in multi-quark systems are discussed in this report.
↳ hep-phnucl-th6 citations
11
Coupled dynamics of heavy and light flavor flow harmonics from EPOSHQ
P.B. Gossiaux🇫🇷 · J. Aichelin🇫🇷 · M. Nahrgang🇫🇷 · V. Ozvenchuk🇵🇱 · K. Werner🇫🇷
We pursue the study of event by event correlations between low-mass particles and heavy mesons flow harmonics in ultrarelativistic heavy ion collisions and clarify some ambiguities found in one of our previous work.
↳ hep-phnucl-thEPJ Web Conf.(2018)·1 citation
12
Probing electron-argon scattering for liquid-argon based neutrino-oscillation program
V. Pandey🇺🇸 · D. Abrams🇺🇸 · S. Alsalmi🇺🇸 · A. M. Ankowski🇺🇸 · J. Bane🇺🇸 · O. Benhar🇮🇹 · H. Dai🇺🇸 · D. B. Day🇺🇸 · D. W. Higinbotham🇺🇸 · C. Mariani🇺🇸 · M. Murphy🇺🇸 · D. Nguyen🇺🇸
The electron scattering has been a vital tool to study the properties of the target nucleus for over five decades. Though, the particular interest on $^{40}$ Ar nucleus stemmed from the progress in the accelerator-based neutrino-oscillation experiments. The complexity of nuclei comprising the detectors and their weak response turned out to be one of the major hurdles in the quest of achieving unprecedented precision in these experiments. The challenges are further magnified by the use of Liquid Argon Time Projection Chambers (LArTPCs) in the short- (SBN) and long-baseline (DUNE) neutrino program, with almost non-existence electron-argon scattering data and hence with no empirical basis to test and develop nuclear models for $^{40}$ Ar. In light of these challenges, an electron-argon experiment, E12-14-012, was proposed at Jefferson Lab. The experiment has recently successfully completed collecting data for $(e, e^{'} p)$ and $(e, e^{'})$ processes, not just on $^{40}$ Ar but also on $^{48}$ Ti, and $^{12}$ C targets. While the analysis is running with full steam, in this contribution, we present a brief overview of the experiment.
↳ nucl-exhep-exnucl-thphysics.ins-det3 citations
13
Hidden charm pentaquark and $Λ (1405)$ in the $Λ_{b}^{0} \to η_{c} K^{-} p (π Σ)$ reaction
Ju-Jun Xie🇨🇳 · Wei-Hong Liang🇨🇳 · Eulogio Oset🇪🇸
We have performed a study of the $Λ_{b}^{0} \to η_{c} K^{-} p$ and $Λ_{b}^{0} \to η_{c} π Σ$ reactions based on the dominant Cabibbo favored weak decay mechanism. We show that the $K^{-} p$ produced only couples to $Λ^{*}$ states, not $Σ^{*}$ and that the $π Σ$ state is only generated from final state interaction of $K ˉ N$ and $η Λ$ channels which are produced in a primary stage. This guarantees that the $π Σ$ state is generated in isospin $I = 0$ and we see that the invariant mass produces a clean signal for the $Λ (1405)$ of higher mass at $1420$ MeV. We also study the $η_{c} p$ final state interaction, which is driven by the excitation of a hidden charm resonance predicted before. We relate the strength of the different invariant mass distributions and find similar strengths that should be clearly visible in an ongoing LHCb experiment. In particular we predict that a clean peak should be seen for a hidden charm resonance that couples to the $η_{c} p$ channel in the invariant $η_{c} p$ mass distribution.
↳ hep-phhep-exnucl-exnucl-thPLB(2018)·15 citations
14
Semiclassical theory of strong localization for quantum thermalization
Christine Khripkov · Amichay Vardi · Doron Cohen
We introduce a semiclassical theory for strong localization that may arise in the context of many-body thermalization. As a minimal model for thermalization we consider a few-site Bose-Hubbard model consisting of two weakly interacting subsystems that can exchange particles. The occupation of a subsystem ( $x$ ) satisfies in the classical treatment a Fokker-Planck equation with a diffusion coefficient $D (x)$ . We demonstrate that it is possible to deduce from the classical description a quantum breaktime $t^{*}$ , and hence the manifestations of a strong localization effect. For this purpose it is essential to take the geometry of the energy shell into account, and to make a distinction between different notions of phasespace exploration.
↳ quant-phcond-mat.quant-gasnucl-thPRE(2018)·6 citations
15
Far-from-equilibrium attractors and nonlinear dynamical systems approach to the Gubser flow
Alireza Behtash🇺🇸 · C. N. Cruz-Camacho🇨🇴 · M. Martinez🇺🇸
The non-equilibrium attractors of systems undergoing Gubser flow within relativistic kinetic theory are studied. In doing so we employ well-established methods of nonlinear dynamical systems which rely on finding the fixed points, investigating the structure of the flow diagrams of the evolution equations, and characterizing the basin of attraction using a Lyapunov function near the stable fixed points. We obtain the attractors of anisotropic hydrodynamics, Israel-Stewart (IS) and transient fluid (DNMR) theories and show that they are indeed non-planar and the basin of attraction is essentially three dimensional. The attractors of each hydrodynamical model are compared with the one obtained from the exact Gubser solution of the Boltzmann equation within the relaxation time approximation. We observe that the anisotropic hydrodynamics is able to match up to high numerical accuracy the attractor of the exact solution while the second order hydrodynamical theories fail to describe it. We show that the IS and DNMR asymptotic series expansion diverge and use resurgence techniques to perform the resummation of these divergences. We also comment on a possible link between the manifold of steepest descent paths in path integrals and basin of attraction for the attractors via Lyapunov functions that opens a new horizon toward effective field theory description of hydrodynamics. Our findings indicate that anisotropic hydrodynamics is an effective theory for far-from-equilibrium fluid dynamics which resums the Knudsen and inverse Reynolds numbers to all orders.
↳ hep-thcond-mat.stat-mechnlin.CDnucl-thPRD(2018)·110 citations
16
Coherent and incoherent $J/ ψ$ photonuclear production in an energy-dependent hot-spot model
Jan Cepila🇨🇿 · Jesus Guillermo Contreras🇨🇿 · Michal Krelina🇨🇱
In a previous publication, we have presented a model for the photoproduction of $J/ ψ$ vector mesons off protons, where the proton structure in the impact-parameter plane is described by an energy-dependent hot-spot profile. Here we extend this model to study the photonuclear production of $J/ ψ$ vector mesons in coherent and incoherent interactions of heavy nuclei. We study two methods to extend the model to the nuclear case: using the standard Glauber-Gribov formalism and using geometric scaling to obtain the nuclear saturation scale. We find that the incoherent cross section changes sizably with the inclusion of subnucleonic hot spots, and that this change is energy dependent. We propose to search for this behavior by measuring the ratio of the incoherent to coherent cross section at different energies. We compare the results of our model to results from RHIC and from the Run 1 at the LHC finding a satisfactory agreement. We also present predictions for the LHC at the new energies reached in Run 2. The predictions include $J/ ψ$ production in ultra-peripheral collisions, as well as the recently observed photonuclear production in peripheral collisions.
↳ hep-phnucl-thPRC(2018)·133 citations
17
Observation of deconfinement in a cold dense quark medium
V. G. Bornyakov🇷🇺 · V. V. Braguta🇷🇺 · E.-M. Ilgenfritz🇷🇺 · A. Yu. Kotov🇷🇺 · A. V. Molochkov🇷🇺 · A. A. Nikolaev🇷🇺
In this paper we study the confinement/deconfinement transition in lattice $S U (2)$ QCD at finite quark density and zero temperature. The simulations are performed on an $3 2^{4}$ lattice with rooted staggered fermions at a lattice spacing $a = 0.044 fm$ . This small lattice spacing allowed us to reach very large baryon density (up to quark chemical potential $μ_{q} > 2000 MeV$ ) avoiding strong lattice artifacts. In the region $μ_{q} \sim 1000 MeV$ we observe for the first time the confinement/deconfinement transition which manifests itself in rising of the Polyakov loop and vanishing of the string tension $σ$ . After the deconfinement is achieved at $μ_{q} > 1000 MeV$ , we observe a monotonous decrease of the spatial string tension $σ_{s}$ which ends up with $σ_{s}$ vanishing at $μ_{q} > 2000 MeV$ . From this observation we draw the conclusion that the confinement/deconfinement transition at finite density and zero temperature is quite different from that at finite temperature and zero density. Our results indicate that in very dense matter the quark-gluon plasma is in essence a weakly interacting gas of quarks and gluons without a magnetic screening mass in the system, sharply different from a quark-gluon plasma at large temperature.
↳ hep-lathep-phhep-thnucl-thJHEP(2018)·41 citations
18
Comprehending Isospin breaking effects of $X (3872)$ in a Friedrichs-model-like scheme
Zhi-Yong Zhou🇨🇳 · Zhiguang Xiao🇨🇳
Recently, we have shown that the $X (3872)$ state can be naturally generated as a bound state by incorporating the hadron interactions into the Godfrey-Isgur quark model using the Friedrichs-like model combined with the QPC model, in which the wave function for the $X (3872)$ as a combination of the bare $c c ˉ$ state and the continuum states can also be obtained. Under this scheme, we now investigate the isospin breaking effect of $X (3872)$ in its decays to $J / ψ π^{+} π^{-}$ and $J / ψ π^{+} π^{-} π^{0}$ . By Considering its dominant continuum parts coupling to $J / ψ ρ$ and $J / ψ ω$ through the quark rearrangement process, one could obtain the reasonable ratio of $B (X (3872) \to J / ψ π^{+} π^{-} π^{0}) / B (X (3872) \to J / ψ π^{+} π^{-}) ≃ (0.58 \sim 0.92)$ . It is also shown that the $D ˉ D^{*}$ invariant mass distributions in the $B \to D ˉ D^{*} K$ decays could be understood qualitatively at the same time. This scheme may provide more insight to understand the enigmatic nature of the $X (3872)$ state.
↳ hep-phhep-exnucl-thPRD(2018)·31 citations
19
Baryon interactions from lattice QCD with physical quark masses -- Nuclear forces and $ΞΞ$ forces --
Takumi Doi🇯🇵 · Takumi Iritani🇯🇵 · Sinya Aoki🇯🇵 · Shinya Gongyo🇯🇵 · Tetsuo Hatsuda🇯🇵 · Yoichi Ikeda🇯🇵 · Takashi Inoue🇯🇵 · Noriyoshi Ishii🇯🇵 · Takaya Miyamoto🇯🇵 · Hidekatsu Nemura🇯🇵 · Kenji Sasaki🇯🇵
We present the latest lattice QCD results for baryon interactions obtained at nearly physical quark masses. $N_{f} = 2 + 1$ nonperturbatively $O (a)$ -improved Wilson quark action with stout smearing and Iwasaki gauge action are employed on the lattice of $(96 a)^{4} ≃ (8.1 \mbox f m)^{4}$ with $a^{- 1} ≃ 2.3$ GeV, where $m_{π} ≃ 146$ MeV and $m_{K} ≃ 525$ MeV. In this report, we study the two-nucleon systems and two- $Ξ$ systems in $^{1} S_{0}$ channel and $^{3} S_{1}$ - $^{3} D_{1}$ coupled channel, and extract central and tensor interactions by the HAL QCD method. We also present the results for the $N Ω$ interaction in $^{5} S_{2}$ channel which is relevant to the $N Ω$ pair-momentum correlation in heavy-ion collision experiments.
↳ hep-lathep-phnucl-exnucl-thEPJ Web Conf.(2018)·39 citations
20
Spin Dependence of Small-Angle Proton-Nucleus Scattering
Michal Krelina🇨🇱 · Boris Z. Kopeliovich🇨🇱
We study the single-spin asymmetry, $A_{N} (t)$ , arising from Coulomb-nuclear interference (CNI) at small 4-momentum transfer squared, $- t = q^{2}$ , aiming at explanation of the recent data from the PHENIX experiment at RHIC on polarized proton-nucleus scattering, exposing a nontrivial $t$ -dependence of $A_{N}$ . We found that the failure of previous theoretical attempts to explain these data, was due to lack of absorptive corrections in the Coulomb amplitude of $p A$ elastic scattering. Our prominent observation is that the main contribution to $A_{N} (t)$ comes from interference of the amplitudes of ultra-peripheral and central collisions.
↳ hep-phnucl-th1 citation
21
Measurements of spin alignment of vector mesons and global polarization of hyperons with ALICE at the LHC
Bedangadas Mohanty (for the ALICE Collaboration)🇮🇳
We present the measurements related to global polarization of $Λ$ hyperons and spin alignment of $K^{* 0}$ vector mesons at mid-rapidity for Pb-Pb collisions at $s_{NN}$ = 2.76 TeV using the ALICE detector at the LHC. The global polarization measurements are carried out with respect to the first order event plane while the spin alignment measurements are carried out with respect to the production plane. No global polarization signal for $Λ$ is observed for 5-15\% and 15-50\% central Pb-Pb collisions. The spin density matrix element $ρ_{00}$ is found to have values slightly below 1/3 at low transverse momentum ( $p_{T}$ ) for $K^{* 0}$ mesons, while it is consistent with 1/3 (no spin alignment) at higher $p_{T}$ . No spin alignment is observed for $K^{* 0}$ in pp collisions at $s$ = 13 TeV and for the spin zero hadron $K_{S}^{0}$ in 20-40\% Pb-Pb collisions at $s_{NN}$ = 2.76 TeV.
↳ nucl-exhep-exhep-phnucl-thEPJ Web Conf.(2018)·19 citations
22
Lattice QCD input for nuclear structure and reactions
Zohreh Davoudi🇺🇸
Explorations of the properties of light nuclear systems beyond their lowest-lying spectra have begun with Lattice Quantum Chromodynamics. While progress has been made in the past year in pursuing calculations with physical quark masses, studies of the simplest nuclear matrix elements and nuclear reactions at heavier quark masses have been conducted, and several interesting results have been obtained. A community effort has been devoted to investigate the impact of such Quantum Chromodynamics input on the nuclear many-body calculations. Systems involving hyperons and their interactions have been the focus of intense investigations in the field, with new results and deeper insights emerging. While the validity of some of the previous multi-nucleon studies has been questioned during the past year, controversy remains as whether such concerns are relevant to a given result. In an effort to summarize the newest developments in the field, this talk will touch on most of these topics.
↳ hep-latnucl-thEPJ Web Conf.(2018)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE