Nuclear Theory·nucl-th

Wednesday·August 25, 2021

11 papers—3 primary·8 cross-listed

04
Electromagnetic Field Produced in High Energy Small Collision System within Charge Density Models of Nucleon
Zong-Wei Zhang🇨🇳 · Xian-Zhuo Cen🇨🇳 · Wei-Tian Deng🇨🇳
Recent experiments show that $Δ γ$ , an observable designed for detecting the chiral magnetic effect (CME), in small collision system $p + A$ is similar with that in heavy ion collision $A + A$ . This brings a challenge to the existence of CME because it is believed that there is no azimuthal correlation between the orientation of the magnetic field ( $Φ_{B}$ ) and the participant plane ( $Φ_{2}$ ) in small collision system. In this work, we introduce three charge density models to describe the inner charge distributions of proton and neutron, and calculate the electric and magnetic fields produced in small $p + A$ collisions at both RHIC and LHC energies. Our results show that the contribution of the single projectile proton to the magnetic field is the main source after average over all participants. The azimuthal correlation between $Φ_{B}$ and $Φ_{2}$ is small but not vanished. And due to the huge fluctuation of fields strength, the magnetic-field contribution to $Δ γ$ could be large.
↳ hep-phnucl-thCPC(2022)·5 citations
05
Coherent energy loss effects in dihadron azimuthal angular correlations in Deep Inelastic Scattering at small $x$
Filip Bergabo🇺🇸 · Jamal Jalilian-Marian🇺🇸
We perform an exploratory study of the role of coherent, medium-induced energy loss in azimuthal angular correlations in dihadron production in Deep Inelastic Scattering (DIS) at small $x$ where the target proton/nucleus is modeled as a Color Glass Condensate. In this approach coherent radiative energy loss is part of the higher order corrections to the leading order dihadron production cross section. We include the effects of both gluon saturation and coherent radiative energy loss and show that radiative cold-matter energy loss has a significant effect on the so-called coincidence probability for the back to back production of dihadrons in DIS. We also define a double ratio of coincidence probabilities for a nucleus and proton targets and show that it is very robust against higher order radiative corrections.
↳ hep-phnucl-thNPA(2022)·16 citations
06
Mass spectra of doubly heavy tetraquarks in an improved chromomagnetic interaction model
Tao Guo🇨🇳 · Jianing Li🇨🇳 · Jiaxing Zhao🇨🇳 · Lianyi He🇨🇳
Doubly heavy tetraquark states are the prime candidates for tightly bound exotic states. We present a systematic study of the mass spectra of the $S$ -wave doubly heavy tetraquark states $QQ q ˉ q ˉ$ ( $q = u, d, s$ and $Q = c, b$ ) with different quantum numbers $J^{P} = 0^{+}$ , $1^{+}$ , and $2^{+}$ in the framework of the improved chromomagnetic interaction (ICMI) model. The parameters in the ICMI model are obtained by fitting the conventional hadron spectra and are used directly to predict the masses of the tetraquark states. For heavy quarks, the uncertainties of the parameters are obtained by comparing the masses of doubly and triply heavy baryons with those given by lattice QCD, QCD sum rules, and potential models. Several compact and stable bound states are found in both the doubly charmed and doubly bottomed tetraquark systems. The predicted mass of the $cc u ˉ d ˉ$ state is consistent with the recent measurement from the LHCb collaboration.
↳ hep-phnucl-thPRD(2022)·61 citations
07
Bosonic fluctuations in the $(1 + 1)$ -dimensional Gross-Neveu(-Yukawa) model at varying $μ$ and $T$ and finite $N$
Jonas Stoll🇩🇪 · Niklas Zorbach🇩🇪 · Adrian Koenigstein🇩🇪 · Martin J. Steil🇩🇪 · Stefan Rechenberger🇩🇪
Using analogies between flow equations from the Functional Renormalization Group and flow equations from (numerical) fluid dynamics we investigate the effects of bosonic fluctuations in a bosonized Gross-Neveu model -- namely the Gross-Neveu-Yukawa model. We study this model for finite numbers of fermions at varying chemical potential and temperature in the local potential approximation. Thereby we numerically demonstrate that for any finite number of fermions and as long as the temperature is non-zero, there is no $Z_{2}$ symmetry breaking for arbitrary chemical potentials.
↳ hep-phcond-mat.str-elnucl-th50 citations
08
Construction of energy density functional for arbitrary spin polarization using functional renormalization group
Takeru Yokota🇯🇵 · Tomoya Naito🇯🇵
We show an application of the functional-renormalization-group aided density functional theory to the homogeneous electron gas with arbitrary spin polarization, which gives the energy density functional in the local spin density approximation. The correlation energy per particle is calculated at arbitrary Wigner-Seitz radius $r_{s}$ and spin polarization $ζ$ . In the high-density region, our result shows good agreement with Monte Carlo (MC) data. The agreement with MC data is better in the case of small spin polarization, while the discrepancy increases as the spin polarization increases. The magnetic properties given by our numerical results are also discussed.
↳ cond-mat.str-elcond-mat.quant-gashep-thnucl-thPRB(2022)·4 citations
09
Transversity GPDs of the proton from lattice QCD
Constantia Alexandrou🇨🇾 · Krzysztof Cichy🇵🇱 · Martha Constantinou🇺🇸 · Kyriakos Hadjiyiannakou🇨🇾 · Karl Jansen🇩🇪 · Aurora Scapellato🇺🇸 · Fernanda Steffens🇩🇪
We present the first calculation of the $x$ -dependence of the isovector transversity generalized parton distributions (GPDs) for the proton within lattice QCD. We compute the matrix elements with non-local operators containing a Wilson line. The calculation implements the Breit symmetric frame. The proton momenta are chosen as $0.83, 1.25, 1.67$ GeV, and the values of the momentum transfer squared are $0.69, 1.02$ GeV $^{2}$ . These combinations include cases with zero and nonzero skewness. The calculation is performed using one ensemble of two degenerate-mass light, a strange and a charm quark of maximally twisted mass fermions with a clover term. The lattice results are renormalized non-perturbatively and finally matched to the light-cone GPDs using one-loop perturbation theory within the framework of large momentum effective theory. The final GPDs are given in the $MS$ scheme at a scale of 2 GeV. In addition to the individual GPDs, we form the combination of the transversity GPDs that is related to the transverse spin structure of the proton. Finally, we extract the lowest two moments of GPDs and draw a number of important qualitative conclusions.
↳ hep-lathep-exhep-phhep-th+1PRD(2022)·82 citations
10
A variational study of two-nucleon systems with lattice QCD
Saman Amarasinghe🇺🇸 · Riyadh Baghdadi🇺🇸 · Zohreh Davoudi🇺🇸 · William Detmold🇺🇸 · Marc Illa🇪🇸 · Assumpta Parreno🇪🇸 · Andrew V. Pochinsky🇺🇸 · Phiala E. Shanahan🇺🇸 · Michael L. Wagman🇺🇸
The low-energy spectrum and scattering of two-nucleon systems are studied with lattice quantum chromodynamics using a variational approach. A wide range of interpolating operators are used: dibaryon operators built from products of plane-wave nucleons, hexaquark operators built from six localized quarks, and quasi-local operators inspired by two-nucleon bound-state wavefunctions in low-energy effective theories. Sparsening techniques are used to compute the timeslice-to-all quark propagators required to form correlation-function matrices using products of these operators. Projection of these matrices onto irreducible representations of the cubic group, including spin-orbit coupling, is detailed. Variational methods are applied to constrain the low-energy spectra of two-nucleon systems in a single finite volume with quark masses corresponding to a pion mass of 806 MeV. Results for S- and D-wave phase shifts in the isospin singlet and triplet channels are obtained under the assumption that partial-wave mixing is negligible. Tests of interpolating-operator dependence are used to investigate the reliability of the energy spectra obtained and highlight both the strengths and weaknesses of variational methods. These studies and comparisons to previous studies using the same gauge-field ensemble demonstrate that interpolating-operator dependence can lead to significant effects on the two-nucleon energy spectra obtained using both variational and non-variational methods, including missing energy levels and other discrepancies. While this study is inconclusive regarding the presence of two-nucleon bound states at this quark mass, it provides robust upper bounds on two-nucleon energy levels that can be improved in future calculations using additional interpolating operators and is therefore a step toward reliable nuclear spectroscopy from the underlying Standard Model of particle physics.
↳ hep-lathep-phnucl-thPRD(2023)·93 citations
11
Sensitivity to the initial conditions of the Time-Dependent Density Functional Theory
Aurel Bulgac🇺🇸 · Ibrahim Abdurrahman🇺🇸 · Gabriel Wlazłowski🇺🇸
Time-Dependent Density Functional Theory is mathematically formulated through non-linear coupled time-dependent 3-dimensional partial differential equations and it is natural to expect a strong sensitivity of its solutions to variations of the initial conditions, akin to the butterfly effect ubiquitous in classical dynamics. Since the Schrödinger equation for an interacting many-body system is however linear and mathematically the exact equations of the Density Functional Theory reproduce the corresponding one-body properties, it would follow that the Lyapunov exponents are also vanishing within a Density Functional Theory framework. Whether for realistic implementations of the Time-Dependent Density Functional Theory the question of absence of the butterfly effect and whether the dynamics provided is indeed a predictable theory was never discussed. At the same time, since the time-dependent density functional theory is a unique tool allowing us the study of non-equilibrium dynamics of strongly interacting many-fermion systems, the question of predictability of this theoretical framework is of paramount importance. Our analysis, for a number of quantum superfluid many-body systems (unitary Fermi gas, nuclear fission, and heavy-ion collisions) with a classical equivalent number of degrees of freedom $O (1 0^{10})$ and larger, suggests that its maximum Lyapunov exponents are negligible for all practical purposes.
↳ cond-mat.stat-mechnucl-thquant-phPRC(2022)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE