Nuclear Theory·nucl-th

Thursday·December 30, 2021

27 papers—13 primary·14 cross-listed

14
Energy dependence of the chiral magnetic effect in expanding holographic plasma
Casey Cartwright🇺🇸 · Matthias Kaminski🇺🇸 · Bjoern Schenke🇺🇸
Based on a holographic far-from-equilibrium calculation of the chiral magnetic effect~(CME) in an expanding quark gluon plasma, we study collisions at various energies. We compute the time evolution of the CME current in the presence of a time-dependent axial charge density and subject to a time-dependent magnetic field. The plasma expansion leads to a dilution of the CME current. We study distinct combinations of how the initial magnetic field and initial axial charge behave with changing initial energy as proposed in previous literature. Most scenarios we consider lead to an increasing time-integrated CME current, when increasing the initial energy. This would make it more likely to observe the CME at higher collision energies.
↳ hep-phhep-thnucl-thPRC(2022)·18 citations
15
An Effective Field Theory of Magneto-Elasticity
Shashin Pavaskar🇺🇸 · Riccardo Penco🇺🇸 · Ira Z. Rothstein🇺🇸
We utilize the coset construction to derive the effective field theory of magnon-phonon interactions in (anti)-ferromagnetic and ferrimagnetic insulating materials. The action is used to calculate the equations of motion which generalize the Landau-Lifshitz and stress equations to allow for magneto-acoustic couplings to all orders in the fields at lowest order in the derivative expansion. We also include the symmetry breaking effects due to Zeeman, and Dzyaloshinsky-Moriya interactions. This effective theory is a toolbox for the study of magneto-elastic phenomena from first principles. As an example we use this theory to calculate the leading order contribution to the magnon decay width due to its the decay into phonons.
↳ hep-thcond-mat.mes-hallgr-qchep-ph+1SciPost Phys.(2022)·19 citations
16
Pion and Kaon box contribution to $a_{μ}^{HLbL}$
Ángel Miramontes🇲🇽 · Adnan Bashir🇲🇽 · Khépani Raya🇪🇸 · Pablo Roig🇲🇽
We present an evaluation of the $π^{\pm}$ and $K^{\pm}$ box contributions to the hadronic light-by-light piece of the muon's anomalous magnetic moment, $a_{μ}$ . The calculation of the corresponding electromagnetic form factors (EFFs) is performed within a Dyson-Schwinger equations (DSE) approach to quantum chromodynamics. These form factors are calculated in the so-called rainbow-ladder (RL) truncation, following two different evaluation methods and, subsequently, in a further improved approximation scheme which incorporates meson cloud effects. The results are mutually consistent, indicating that in the domain of relevance for $a_{μ}$ the obtained EFFs are practically equivalent. Our analysis yields the combined estimates of $a_{μ}^{π^{\pm} - b o x} = - (15.6 \pm 0.2) \times 1 0^{- 11}$ and $a_{μ}^{K^{\pm} - box} = - (0.48 \pm 0.02) \times 1 0^{- 11}$ , in full agreement with results previously obtained within the DSE formalism and other contemporary estimates.
↳ hep-phnucl-thPRD(2022)·50 citations
17
Model studies of V0 production ratios in $pp$ collisions at $s$ = 0.2, 0.9, and 7 TeV
M. Ajaz🇵🇰 · M.U. Ashraf🇵🇰 · M. Waqas🇨🇳 · Z. Yasin🇵🇰 · A.M. Khubrani🇸🇦 · S. Hassan🇵🇰 · A. Haj Ismail🇦🇪 · L.L. Li🇨🇳
A comparative study of $V^{0}$ ratios has been performed between HIJING, Sibyll and QGSJET model-based event generators in this paper. The ratios under study are {\alam}/{\lam}, {\alam}/{\ks} and {\xim}/{\lam} as a function of rapidity $y$ , rapidity loss ( $Δ y$ ) and {\ppt} from $pp$ collisions at \sqrts~= 0.2, 0.9, and 7 TeV and these simulations are then compared with the STAR and LHCb fiducial phase spaces in different {\ppt} regions. Although the models could produce some of the ratios in a limited {\ppt} and/or $y$ region, none of them completely predicts the experimental results. The QGSJET has good predictions with the data in most of the cases but since the model does not include the $Ξ$ particle definition, therefore it does not give any predictions for $Ξ$ /{\lam} ratios. The extrapolation to the highest possible energies can be studied by re-tune some of the basic parameters based on current and previous measurements. These kinds of systematic comparison studies are also useful to apply certain constraints on the pQCD and non-pQCD-based hadronic event generators to significantly improve the predictions of Standard Model physics at the RHIC and LHC experimental data for the understanding of underlying physics mechanisms in high energy collisions.
↳ hep-phnucl-thEur.Phys.J.Plus(2023)·9 citations
18
Light-quark mass dependence of the nucleon axial charge and pion-nucleon scattering phenomenology
Fernando Alvarado🇪🇸 · Luis Alvarez-Ruso🇪🇸
The light-quark mass dependence of the nucleon axial isovector charge ( $g_{A}$ ) has been studied up to next-to-next-to-leading order, $O (p^{4})$ , in relativistic chiral perturbation theory using extended-on-mass-shell renormalization, without and with explicit $Δ (1232)$ degrees of freedom. We show that in the $Δ$ -less case, at this order, the flat trend of $g_{A} (M_{π})$ exhibited by state-of-the-art lattice QCD (LQCD) results cannot be reproduced using low energy constants (LECs) extracted from pion-nucleon elastic and inelastic scattering. A satisfactory description of these LQCD data is only achieved in the theory with $Δ$ . From this fit we report $g_{A} (M_{π (phys)}) = 1.260 \pm 0.012$ , close to the experimental result, and $d_{16} = - 0.88 \pm 0.88$ GeV $^{- 2}$ , in agreement with its empirical value. The large uncertainties are of theoretical origin, reflecting the difference between $O (p^{3})$ and $O (p^{4})$ that still persists at large $M_{π}$ in presence of the $Δ$ .
↳ hep-phhep-latnucl-thPRD(2022)·15 citations
19
An energy independent scaling of transverse momentum spectra of direct (prompt) photons from two-body processes in high-energy proton-proton collisions
Qiang Zhang🇨🇳 · Ya-Qin Gao🇨🇳 · Fu-Hu Liu🇨🇳 · Khusniddin K. Olimov🇺🇿
Transverse momentum spectra of direct (prompt) photons from two-body processes in high-energy proton-proton (p+p) collisions are analyzed in this paper. We collected the experimental invariant cross-sections at mid-rapidity in p+p collisions measured by the UA6, CCOR, R806, R110, PHENIX, NA24, CMS, ALICE, and ATLAS Collaborations over a center-of-mass energy range from 24.3 GeV to 13 TeV. In fitting the data, we used different kinds of functions which include the revised Tsallis--Pareto-type function (the TP-like function) at the particle level, the convolution of two TP-like functions at the quark level, and the root-sum-of-squares of two revised Tsallis-like functions in which the quark chemical potentials $μ_{i} = μ_{B} /3$ or $μ_{i} = 0$ , where $μ_{B}$ is the baryon chemical potential. We have extracted the values of three main free parameters: the effective temperature $T$ , power index $n_{0}$ (or entropy index $q$ ), and correction index $a_{0}$ . After analyzing the changing trends of the parameters, we found that $T$ , $q$ , and $a_{0}$ increase and $n_{0}$ decreases with the increase of collision energy. Based on the analyses of transverse momentum spectra, an energy independent scaling, i.e. the $x_{T}$ scaling, is obtained.
↳ hep-phhep-exnucl-exnucl-thAnnalen Phys.(2022)·7 citations
20
Dark Matter Effects on the Compact Star Properties
H. C. Das · Ankit Kumar · Bharat Kumar · S. K. Patra
The neutron star properties are generally determined by the equation of state of $β$ -equilibrated dense matter. In this work, we consider the interaction of fermionic dark matter (DM) particles with the nucleons via Higgs exchange and investigate its effect on the neutron star properties with the relativistic mean-field model equation of state coupled with DM. We deduce that DM significantly affects the neutron star properties, such as considerably reduce the maximum mass of the star, which depends on the percentage of the DM considered inside the neutron star. The tidal Love numbers both for electric and magnetic cases and surficial Love numbers are also studied for DM admixed NS. It is observed that the magnitude of tidal and surficial Love numbers increase with more DM percentage. Further, we point out that post-Newtonian tidal corrections to gravitational waves decreased by increasing DM percentage. Also, the DM effect on the GW signal is significant during the late inspiral and merger stages of binary evolution for GW frequencies >500 Hz.
↳ astro-ph.HEgr-qcnucl-thGalaxies(2022)·46 citations
21
Towards robust constraints on nuclear effective field theory from lattice QCD
Marc Illa (for the NPLQCD Collaboration)🇪🇸
We will discuss several new results from the NPLQCD Collaboration that combine lattice QCD results on (hyper)nuclear systems at unphysical pion masses together with nuclear effective field theories. Two-baryon channels with strangeness $0$ to $- 4$ are analyzed, with findings that point to interesting symmetries observed in hypernuclear forces as predicted in the limit of QCD with a large number of colors. Also, several matrix elements of light nuclei are studied. The tritium axial charge, related to the Gamow-Teller matrix element, and the longitudinal momentum fraction of $^{3}$ He that is carried by the isovector combination of $u$ and $d$ are extracted and extrapolated to the physical point. For this latter case, it can be seen how including lattice results to experimental determinations can have imminent potential to enable more precise determinations and to reveal the QCD origins of the EMC effect.
↳ hep-lathep-phnucl-thPoS(2022)·2 citations
22
Tidal Deformability as a Probe of Dark Matter in Neutron Stars
Davood Rafiei Karkevandi🇮🇷 · Soroush Shakeri🇮🇷 · Violetta Sagun🇵🇹 · Oleksii Ivanytskyi🇵🇱
The concept of boson stars (BSs) was first introduced by Kaup and Ruffini-Bonazzola in the 1960s. Following this idea, we investigate an effect of self-interacting asymmetric bosonic dark matter (DM) according to Colpi et al. model for BSs (1986) on different observable properties of neutron stars (NSs). In this paper, the bosonic DM and baryonic matter (BM) are mixed together and interact only through gravitational force. The presence of DM as a core of a compact star or as an extended halo around it is examined by applying different boson masses and DM fractions for a fixed coupling constant. The impact of DM core/halo formations on a DM admixed NS properties is probed through the maximum mass and tidal deformability of NSs. Thanks to the recent detection of Gravitational-Waves (GWs) and the latest X-ray observations, the DM admixed NS's features are compared to LIGO/Virgo and NICER results.
↳ astro-ph.HEgr-qchep-phnucl-thPublished by the World Scientific, Procee…·24 citations
23
Digital Quantum Simulation of the Schwinger Model and Symmetry Protection with Trapped Ions
Nhung H. Nguyen🇺🇸 · Minh C. Tran🇺🇸 · Yingyue Zhu🇺🇸 · Alaina M. Green🇺🇸 · C. Huerta Alderete🇺🇸 · Zohreh Davoudi🇺🇸 · Norbert M. Linke🇺🇸
Tracking the dynamics of physical systems in real time is a prime application of digital quantum computers. Using a trapped-ion system with up to six qubits, we simulate the real-time dynamics of a lattice gauge theory in 1+1 dimensions, i.e., the lattice Schwinger model, and demonstrate non-perturbative effects such as pair creation for times much longer than previously accessible. We study the gate requirement of two formulations of the model using the Suzuki-Trotter product formula, as well as the trade-off between errors from the ordering of the Hamiltonian terms, the Trotter step size, and experimental imperfections. To mitigate experimental errors, a recent symmetry-protection protocol for suppressing coherent errors and a symmetry-inspired post-selection scheme are applied. This work demonstrates the integrated theoretical, algorithmic, and experimental approach that is essential for efficient simulation of lattice gauge theories and other complex physical systems.
↳ quant-phhep-lathep-phnucl-thPRX Quantum(2022)·181 citations
24
Quantum kinetic theory for spin transport of quarks with background chromo-electromagnetic fields
Di-Lun Yang🇹🇼
We derive the quantum kinetic equations for massive and massless quarks coupled with the background chromo-electromagnetic fields from the Wigner-function approach with the $ℏ$ expansion and effective power-counting scheme. For each case, one obtains coupled color-singlet and color-octet kinetic equations, which also involve the scalar and axial-vector components for the charge and spin transport. These kinetic equations delineate entangled evolution of the corresponding distribution functions decomposed in color space. At weak coupling, we derive the close form of the color-singlet kinetic equations for spin transport, which incorporates the diffusion term and the source term that triggers dynamical spin polarization led by correlation functions of color fields. Also, the non-dynamical source term is found in the axial Wigner function. The induced spin polarization and axial charge currents by these source terms are discussed under physical assumptions for color-field correlators in near-equilibrium quark gluon plasmas. In the constant-field limit, we further obtain non-vanishing axial Ward identities, from which we extract the pseudo-scalar condensate for massive quarks at finite temperature.
↳ hep-phhep-thnucl-thJHEP(2022)·31 citations
25
Kaon and Nucleon States with Hidden Charm
Brenda B. Malabarba🇧🇷 · A. Martínez Torres🇧🇷 · K.P. Khemchandani🇧🇷 · Xiu-Lei Ren🇩🇪 · Li-Sheng Geng🇨🇳
In this talk we discuss the formation of exotic hadrons with hidden charm arising from three-body interactions. To be more specific, in the strangeness sector, we predict the existence of a mesonic state, $K^{*} (4307)$ , which is dynamically generated from the three-body interactions of the $K D D ˉ^{*}$ system, has mass around $4307$ MeV and quantum numbers $I (J^{P}) = 1/2 (1^{-})$ . In the baryonic sector, we predict the existence of $N^{*}$ states, which are generated from the three-body interactions of the $N D D ˉ^{*}$ system, with masses around $4400 \sim 4600$ MeV, widths of $2 \sim 20$ MeV and positive parity.
↳ hep-phnucl-thRev.Mex.Fis.Suppl.(2022)·0 citations
26
S-wave pion-pion scattering lengths from nucleon-meson fluctuations
Jürgen Eser🇫🇷 · Jean-Paul Blaizot🇫🇷
We present calculations of the $S$ -wave isospin-zero and isospin-two pion-pion scattering lengths within a nucleon-meson model with parity doubling. Both scattering lengths are computed in various approximations, ranging from a mean-field (MF) calculation towards the inclusion of loop corrections by means of the functional renormalization group (FRG). The bosonic part of the investigated nucleon-meson model is formulated in terms of stereographic projections as a "natural" set of coordinates on the respective vacuum manifold. We thereby elucidate subtleties concerning the truncation of the effective action w.r.t. higher-derivative pion interactions and the "successful" computation of the scattering lengths. As the main result, we find simultaneous agreement for the isospin-zero and isospin-two scattering lengths with experimental data within the $LPA^{'}$ -truncation of the FRG, together with chiral symmetry breaking (roughly) occurring at the characteristic scale of $4 π f_{π}$ . The isoscalar $σ$ -mass is dynamically generated by the FRG integration of momentum modes, and is a prediction of the model. It ends being of the order of $500 MeV$ , i.e., much lower than the value ( $> 1 GeV$ ) found in MF or one-loop treatment of this or related models. Finally, the convergence of the corresponding low-energy expansion of the quantum effective action in terms of pion momenta is discussed.
↳ hep-phnucl-thPRD(2022)·8 citations
27
Topological tensor invariants and the current algebra approach: Analysis of 196 nonleptonic two-body decays of single and double charm baryons -- a review
Stefan Groote🇪🇪 · Jürgen G. Körner🇩🇪
We shed new light on the standard current algebra approach to the nonleptonic two-body decays of single and double heavy charm baryons. By making use of the completeness relation for the flavor wave functions of the ground state baryon {\bf 20'} representation we are able to rewrite the results of the current algebra approach in terms of the seven topological tensor invariants describing the decays. The representation of the current algebra results in terms of topological tensor invariants depends only on the initial and final state of the process. The summation over intermediate states inherent to the current algebra result is automatically taken care of in the tensor representation. In this way one arrives at a new, quick and very compact assessment of the results of the current algebra/pole model calculation. For example, one can quickly identify the decays in which the p.v.\ $S$ -wave amplitude is predicted to vanish implying zero polarization asymmetries in these decays. We provide tables of the values of the seven topological tensor invariants for all Cabibbo favored and singly and doubly Cabibbo suppressed nonleptonic single and double charm baryon decays. In total we treat 196 charm baryon decays. We also discuss the charm preserving $Δ C = 0$ decays of single charm baryons and the usual hyperon decays.
↳ hep-phhep-exnucl-thEPJC(2022)·27 citations

Affiliations

first authorsco-authorsvia INSPIRE