Nuclear Theory·nucl-th

Wednesday·November 10, 2021

9 papers—3 primary·6 cross-listed

04
Perturbative structure of two- and four-point functions of color charge in a non-Gaussian small- $x$ action
Andre V. Giannini🇧🇷 · Yasushi Nara🇯🇵
We compute the perturbative expansion of the two- and four-point functions of color charges in the Color Glass Condensate framework considering the quartic correction to the McLerran-Venugopalan (MV) model of Gaussian color charge fluctuations. Expressions for these correlators in the perturbative expansion for small and large non-Gaussian color charge fluctuations are derived for arbitrary orders in perturbation theory. We explicitly show that the perturbative series does not converge at higher orders as expected. We apply the Borel-Padé resummation method to our problem to construct a convergent series. It is shown that the fully non-perturbative solution can be described by the Borel-Padé approximants constructed from the first few terms of the perturbative series for small non-Gaussian fluctuations.
↳ hep-phnucl-thEPJC(2022)·3 citations
05
High-precision $Q$ -value measurement and nuclear matrix elements for the double- $β$ decay of $^{98}$ Mo
D.A. Nesterenko🇫🇮 · L. Jokiniemi🇪🇸 · J. Kotila🇫🇮 · A. Kankainen🇫🇮 · Z. Ge🇫🇮 · T. Eronen🇫🇮 · S. Rinta-Antila🇫🇮 · J. Suhonen🇫🇮
Neutrinoless double-beta ( $0 ν β β$ ) decay and the standard two-neutrino double-beta ( $2 ν β β$ ) decay of $^{98}$ Mo have been studied. The double-beta decay $Q$ -value has been determined as $Q_{β β} = 113.668 (68)$ keV using the JYFLTRAP Penning trap mass spectrometer. It is in agreement with the literature value, $Q_{β β} = 109 (6)$ keV, but almost 90 times more precise. Based on the measured $Q$ -value, precise phase-space factors for $2 ν β β$ decay and $0 ν β β$ decay, needed in the half-life predictions, have been calculated. Furthermore, the involved nuclear matrix elements have been computed in the proton-neutron quasiparticle random-phase approximation (pnQRPA) and the microscopic interacting boson model (IBM-2) frameworks. Finally, predictions for the $2 ν β β$ decay are given, suggesting a much longer half-life than for the currently observed cases.
↳ nucl-exnucl-thEPJA(2022)·7 citations
06
$X$ structures in $B^{+} \to J / ψ ϕ K^{+}$ as one-loop and double-triangle threshold cusps
Satoshi X. Nakamura (Univ. of Science and Technology of China)🇨🇳
The LHCb data on $B^{+} \to J / ψ ϕ K^{+}$ show four peaks and three dips in the $J / ψ ϕ$ invariant mass distribution, and the peaks are interpreted as $X (4140)$ , $X (4274)$ , $X (4500)$ and $X (4685) / X (4700)$ resonance contributions. Interestingly, all the peaks and dips are located at (or close to) $D_{s}^{*} D ˉ_{s}^{(*)}$ , $D_{s 0}^{*} (2317) D ˉ_{s}^{(*)}$ , $D_{s 1} (2536) D ˉ_{s}^{(*)}$ , and $ψ^{'} ϕ$ thresholds. These coincidences suggest a close connection between the structures and the thresholds, which however has not been seriously considered in previous theoretical studies on the $X$ structures. In fact, if we utilize this connection and interpret the $X$ structures as common $s$ -wave threshold cusps, we face a difficulty: $X (4274)$ and $X (4500)$ have spin-parity that conflict with the experimentally determined ones. In this work, we introduce double triangle mechanisms that cause threshold cusps significantly sharper than the ordinary one-loop ones of the same spin-parity. We demonstrate that all the $X$ and dip structures are well described by a combination of one-loop and double-triangle threshold cusps, thereby proposing a novel interpretation of the $X$ and dip structures.
↳ hep-phhep-exnucl-thPLB(2022)·12 citations
07
Production rate and ellipticity of lepton pairs from a rotating hot and dense QCD medium
Minghua Wei🇨🇳 · Chowdhury Aminul Islam🇨🇳 · Mei Huang🇨🇳
Using a current-current correlation function (CF), the photon polarization tensor is calculated for a rotating hot and dense QCD medium. The spectral function (SF) and the dilepton rate (DR) are estimated therefrom. Numerical results show that both SF and DR are enhanced in a rotating medium, especially in a low invariant mass region. SF and DR are also explored in the consequences of the interplay among the angular velocity, temperature and chemical potential. We also estimated the electromagnetic screening by calculating the Debye mass and it shows a suppression for a rotating QCD medium. The most interesting observation is the azimuthal anisotropy of the dilepton production, i.e, the elliptic flow $v_{2}$ of the lepton pair induced by the rotation as an external field. The competition between the centrifugal effect and the spin polarization effect due to rotation results in a convex down behaviour of the elliptic flow as a function of the transverse momentum in a relatively large magnitude of angular velocity. It is noticed that quark spin polarization induces a negative $v_{2}$ in the case of large angular velocity.
↳ hep-phnucl-thPRD(2022)·15 citations
08
Exploring the effect of hadron cascade-time on particle production in Xe+Xe collisions at $s_{NN}$ = 5.44 TeV through a multi-phase transport model
Girija Sankar Pradhan🇮🇳 · Rutuparna Rath🇮🇳 · Ronald Scaria🇮🇳 · Raghunath Sahoo🇮🇳
Heavy-ion collisions at ultra-relativistic energies provide extreme conditions of energy density and temperature to produce a deconfined state of quarks and gluons. Xenon (Xe) being a deformed nucleus further gives access to the effect of initial geometry on final state particle production. This study focuses on the effect of nuclear deformation and hadron cascade-time on the particle production and elliptic flow using A Multi-Phase Transport (AMPT) model in Xe+Xe collisions at $s_{NN}$ = 5.44 TeV. We explore the effect of hadronic cascade-time on identified particle production through the study of $p_{T}$ -differential particle ratios. The effect of hadronic cascade-time on the generation of elliptic flow is studied by varying the cascade-time between 5 and 25 fm/ $c$ . This study shows the final state interactions among particles generate additional anisotropic flow with increasing hadron cascade-time, especially at very low and high- $p_{T}$ .
↳ hep-phhep-exnucl-exnucl-thPRC(2022)·9 citations
09
First saturation correction in high energy proton-nucleus collisions: Part III. Ensemble averaging
Ming Li🇺🇸 · Vladimir V. Skokov🇺🇸
In high energy proton-nucleus collisions, the gluon saturation effects from the nucleus are fully incorporated into the light-like Wilson lines. The gluon saturation effects from the proton, which are anticipated to be important either in the extreme high energy limit or towards the dense-dense (nucleus-nucleus) collision regimes, have been studied perturbatively within the Color Glass Condensate effective theory in previous papers of this series. A configuration-by-configuration expression for the single inclusive semi-hard gluon production including the first saturation correction was obtained. In this paper, we perform ensemble averaging in the McLerran-Venugopalan model and the Dipole Approximation. We find that, in the saturation correction, the effects of the initial state interactions are negligible while the final state interactions play most important role and give a positive-valued contribution to the semi-hard gluon spectrum. Furthermore, we show that the single gluon spectrum scales approximately $1/ k_{⊥}^{4}$ at small $k_{⊥}$ , suggesting that a resummation of higher order saturation corrections is required to regulate the infrared region of the gluon spectrum.
↳ hep-phnucl-thJHEP(2022)·10 citations

Affiliations

first authorsco-authorsvia INSPIRE

Perturbative structure of two- and four-point functions of color charge in a non-Gaussian small-x action

High-precision Q-value measurement and nuclear matrix elements for the double-β decay of 98Mo

X structures in B+→J/ψϕK+ as one-loop and double-triangle threshold cusps

Production rate and ellipticity of lepton pairs from a rotating hot and dense QCD medium

Exploring the effect of hadron cascade-time on particle production in Xe+Xe collisions at sNN​​ = 5.44 TeV through a multi-phase transport model

First saturation correction in high energy proton-nucleus collisions: Part III. Ensemble averaging

Affiliations

Perturbative structure of two- and four-point functions of color charge in a non-Gaussian small- $x$ action

High-precision $Q$ -value measurement and nuclear matrix elements for the double- $β$ decay of $^{98}$ Mo

$X$ structures in $B^{+} \to J / ψ ϕ K^{+}$ as one-loop and double-triangle threshold cusps

Exploring the effect of hadron cascade-time on particle production in Xe+Xe collisions at $s_{NN}$ = 5.44 TeV through a multi-phase transport model