Nuclear Theory·nucl-th

Thursday·June 3, 2021

11 papers—3 primary·8 cross-listed

04
Electroproduction of heavy vector mesons using holographic QCD: from near threshold to high energy regimes
Kiminad A. Mamo🇺🇸 · Ismail Zahed🇺🇸
We develop a non-perturbative analysis of the electro-production of heavy vector mesons ( $ϕ$ , $J /Ψ$ ) from threshold to high energy. We use the holographic construction with bulk confinement enforced through a soft wall. Using Witten diagrams, we evaluate the pertinent cross sections for heavy vector mesons ( $ϕ$ , $J /Ψ$ ) production and study their dependence on both the incoming virtual photon polarization as well as the outgoing polarization of the heavy meson. Our results for $J /Ψ$ electro-production compares well with the available HERA data at low and intermediate $Q^{2}$ , and for a wide range of momentum transfer. We also predict the quasi-real electro-production of $J /Ψ$ near threshold.
↳ hep-phhep-exhep-thnucl-ex+1PRD(2021)·25 citations
05
Electromagnetic radii of the nucleon in soft-wall holographic QCD
Kiminad A. Mamo🇺🇸 · Ismail Zahed🇺🇸
We revisit the electromagnetic form factors of the proton and neutron in the original-minimal soft-wall holographic QCD, which has only two parameters, i.e., the mass scale $κ$ and the twist parameter of the nucleon $τ$ . We first fix $τ = 3$ by the hard scattering rule, and extract $κ = 0.402 GeV$ from the world data (including the Mainz A1 data) of the Sachs magnetic form factor of the proton $G_{M}^{p}$ . We then predict among others, the charge radius of the proton to be $r_{p} = 0.831 \pm 0.008 fm$ , in perfect agreement with the recent charge radius of the proton measured by the PRad collaboration at Jefferson Lab, and in agreement with the muonic hydrogen experiments. Our prediction for the proton elastic form factor ratio $μ_{p} G_{E}^{p} / G_{M}^{p}$ is also in very good agreement with the recent high precision Jefferson Lab recoil polarization experiment E08-007 for $Q^{2} = 0.3 - 0.6 GeV^{2}$ , and with the recent high precision Mainz A1 experiment for $Q^{2} < 0.13 GeV^{2}$ .
↳ hep-phhep-exhep-thnucl-ex+1NPB(2023)·18 citations
06
Gibbs entropy from entanglement in electric quenches
Adrien Florio🇺🇸 · Dmitri E. Kharzeev🇺🇸
In quantum electrodynamics with charged fermions, a background electric field is the source of the chiral anomaly which creates a chirally imbalanced state of fermions. This chiral state is realized through the production of entangled pairs of right-moving fermions and left-moving antifermions (or vice versa, depending on the orientation of the electric field). Here we show that the statistical Gibbs entropy associated with these pairs is equal to the entropy of entanglement between the right-moving particles and left-moving antiparticles. We then derive an asymptotic expansion for the entanglement entropy in terms of the cumulants of the multiplicity distribution of produced particles and explain how to re-sum this asymptotic expansion. Finally, we study the time dependence of the entanglement entropy in a specific time-dependent pulsed background electric field, the so-called "Sauter pulse", and illustrate how our resummation method works in this specific case. We also find that short pulses (such as the ones created by high energy collisions) result in an approximately thermal distribution for the produced particles.
↳ hep-thhep-phnucl-thquant-phPRD(2021)·22 citations
07
Effect of the pion field on the distributions of pressure and shear in the proton
Shiryo Owa🇦🇺 · A. W. Thomas🇦🇺 · X.G. Wang🇦🇺
In light of recent experimental progress in determining the pressure and shear distributions in the proton, these quantities are calculated in a model with confined quarks supplemented by the pion field required by chiral symmetry. The incorporation of the pion contributions is shown to account for the long-range distributions, in general agreement with the experimentally extracted quark contributions. The results of the model are also compared with lattice QCD results at unphysically large quark mass.
↳ hep-phhep-exhep-latnucl-thPLB(2022)·14 citations
08
Bottomonia production in p+p collisions under NRQCD formalism
Vineet Kumar🇮🇳 · Kinkar Saha🇮🇳 · Prashant Shukla🇮🇳 · Abhijit Bhattacharyya🇮🇳
In this work, we present the calculation of the production cross sections of bottomonia states using Non-Relativistic Quantum Chromodynamics (NRQCD) formalism. The direct production cross-section of a resonance can be factorised in terms of short distance Quantum Chromodynamics (QCD) cross sections and long distance matrix elements (LDMEs) under NRQCD. We use a large set of measured $Υ$ (nS) production data at Tevatron and LHC energies in both central and forward rapidity regions to extract the LDMEs with better precision. The feed down contributions from the higher states including the $χ_{b}$ (3P) state are taken into account for the LDME extraction. The formalism provides a good description of the bottomonia data in wide transverse momentum range at different collision energies.
↳ hep-phhep-exhep-latnucl-thNPA(2021)·1 citation
09
The Self-energy of Nucleon for the Photon-proton Elastic Scattering and the Electromagnetic Polarizability
Susumu Kinpara
The effect of the self-energy on the photon-proton elastic scattering is investigated for the backward and the forward directions. The shape of the Thomson scattering at the photon energy $ω \to 0$ is broken by taking into account the self-energy of proton. The electromagnetic polarizabilities $α ˉ \pm β ˉ$ are calculated by the lowest-order perturbative treatment.
↳ hep-phnucl-th1 citation
10
In-medium kinetic theory of $D$ mesons and heavy-flavor transport coefficients
Juan M. Torres-Rincon🇩🇪 · Glòria Montaña🇪🇸 · Àngels Ramos🇪🇸 · Laura Tolos🇪🇸
We extend the kinetic theory of $D$ mesons to accommodate thermal and off-shell effects due to the medium modification of the heavy-meson spectral functions. From the Kadanoff-Baym approach we derive the off-shell Fokker-Planck equation which encodes the heavy-flavor transport coefficients. We analyze the thermal width (damping rate) of $D$ mesons due to their scattering off light mesons, focusing on new in-medium effects: off-shell corrections, inelastic channels, and the contribution of the Landau cut. We obtain that the latter effect (absent for vacuum scattering amplitudes) brings sizable corrections at moderate temperatures. We discuss how the heavy-flavor transport coefficients, like the drag and diffusion coefficients, are modified in matter. We find that the $D$ -meson spatial diffusion coefficient matches smoothly to the latest results of lattice-QCD calculations and Bayesian analyses at higher temperatures.
↳ hep-phnucl-thPRC(2022)·24 citations
11
The bosonic algebraic approach applied to the $[QQ] [Q ˉ Q ˉ]$ tetraquarks
A. J. Majarshin🇨🇳 · Yan-An Luo🇨🇳 · Feng Pan🇨🇳 · Jorge Segovia🇪🇸
The exact eigenenergies of the $T_{4 c} = [cc] [c ˉ c ˉ]$ , $T_{4 b} = [bb] [b ˉ b ˉ]$ , and $T_{2 [b c]} = [b c] [b ˉ c ˉ]$ tetraquarks are calculated within the extended transitional Hamiltonian approach, in which the so-called Bethe \emph{ansatz} within an infinite-dimensional Lie algebra is used. We fit the parameters appearing in the transitional region from phenomenology associated with potential candidates of tetraquarks. The rotation and vibration transitional theory seems to provide a better description of heavy tetraquarks than other attempts within the same formalism. Our results indicate that the pairing strengths are large enough to provide binding; an extended comparison with the current literature is also performed.
↳ hep-phhep-exhep-latnucl-ex+1PRD(2022)·17 citations

Affiliations

first authorsco-authorsvia INSPIRE