Nuclear Theory·nucl-th

Tuesday·October 1, 2019

19 papers—11 primary·8 cross-listed

12
Radiative quark $p_{⊥}$ -broadening in a quark-gluon plasma at RHIC and LHC energies
B.G. Zakharov🇷🇺
We study the radiative correction to $p_{⊥}$ -broadening of a fast quark in a quark-gluon plasma beyond the soft gluon approximation. We find that the radiative contribution to quark $⟨ p_{⊥}^{2} ⟩$ for RHIC and LHC conditions is negative.
↳ hep-phnucl-th0 citations
13
A new description of transverse momentum spectra of identified particles produced in proton-proton collisions at high energies
Pei-Pin Yang🇨🇳 · Fu-Hu Liu🇨🇳 · Raghunath Sahoo🇮🇳
The transverse momentum spectra of identified particles produced in high energy proton-proton ( $p + p$ ) collisions are empirically described by a new method with the framework of participant quark model or the multisource model at the quark level, in which the source itself is exactly the participant quark. Each participant (constituent) quark contributes to the transverse momentum spectrum, which is described by the TP-like function, a revised Tsallis--Pareto-type function. The transverse momentum spectrum of the hadron is the convolution of two or more TP-like functions. For a lepton, the transverse momentum spectrum is the convolution of two TP-like functions due to two participant quarks, e.g. projectile and target quarks, taking part in the collisions. A discussed theoretical approach seems to describe the $p + p$ collisions data at center-of-mass energy $s = 200$ GeV, 2.76 TeV, and 13 TeV very well.
↳ hep-phhep-exnucl-exnucl-thAdv.High Energy Phys.(2020)·12 citations
14
Glauber model for small system using anisotropic and inhomogeneous density profile of proton
Suman Deb🇮🇳 · Golam Sarwar🇮🇳 · Dhananjaya Thakur🇮🇳 · Pavish S.🇮🇳 · Raghunath Sahoo🇮🇳 · Jan-e Alam🇮🇳
Recent studies reveal that at high energies, collisions of small system like $p + p$ gives signatures similar to that widely observed in heavy ion collisions hinting towards a possibility of forming a medium with collective behaviour. With this motivation, we have used the Glauber model, which is traditionally applied to heavy ion collisions, in small system using anisotropic and inhomogeneous density profile of proton and found that the proposed model reproduces the charged particle multiplicity distribution of $p + p$ collisions at LHC energies very well. Collision geometric properties like mean impact parameter, mean number of binary collisions ( $⟨ N_{co l l} ⟩$ ) and mean number of participants ( $⟨ N_{p a r t} ⟩$ ) at different multiplicities are determined. Having estimated $⟨ N_{co l l} ⟩$ , we have calculated nuclear modification-like factor ( $R_{H L}$ ) in $p + p$ collisions. We also estimated eccentricity and elliptic flow as a function of charged particle multiplicity using the linear response to initial geometry.
↳ hep-phnucl-exnucl-thPRD(2020)·10 citations
15
Long-distance Contributions to Neutrinoless Double Beta Decay $π^{-} \to π^{+} ee$
Xin-Yu Tuo🇨🇳 · Xu Feng🇨🇳 · Lu-Chang Jin🇺🇸
Neutrinoless double beta decay, if detected, would prove that neutrinos are Majorana fermions and provide the direct evidence for lepton number violation. If such decay would exist in nature, then $π^{-} π^{-} \to ee$ and $π^{-} \to π^{+} ee$ (or equivalently $π^{-} e^{+} \to π^{+} e^{-}$ ) are the two simplest processes accessible via first-principle lattice QCD calculations. In this work, we calculate the long-distance contributions to the $π^{-} \to π^{+} ee$ transition amplitude using four ensembles at the physical pion mass with various volumes and lattice spacings. We adopt the infinite-volume reconstruction method to control the finite-volume effects arising from the (almost) massless neutrino. Providing the lattice QCD inputs for chiral perturbation theory, we obtain the low energy constant $g_{ν}^{π π} (m_{ρ}) = - 10.89 (28)_{stat} (74)_{sys}$ , which is close to $g_{ν}^{π π} (m_{ρ}) = - 11.96 (31)_{stat}$ determined from the crossed-channel $π^{-} π^{-} \to ee$ decay.
↳ hep-lathep-phnucl-exnucl-thPRD(2019)·56 citations
16
The proton structure via double parton scattering
Matteo Rinaldi🇮🇹
In this talk we present the results of the investigation on the so called double parton distribution functions (dPDFs), accessible quantities in high energy proton-proton and proton nucleus collisions, in double parton scattering processes (DPS). These new and almost unknown distributions encode information on how partons inside a proton are correlated among each other and represent a new tool to explore the three dimensional partonic structure of hadrons. In the present contribution, results of the calculations of dPFDs are presented also including phenomenological investigations on the impact of double correlations in experimental observables, showing how the latter could be observed in the next LHC run. In addition we discuss how present information on experimental observables could be related to the transverse proton structure.
↳ hep-phnucl-thJ.Phys.Conf.Ser.(2020)·1 citation
17
Process-independent effective coupling and the pion structure function
José Rodríguez-Quintero🇪🇸 · Lei Chang🇨🇳 · Khépani Raya🇨🇳 · Craig D. Roberts🇨🇳
We sketch the calculation of the pion structure functions within the DSE framework, following two alternative albeit consistent approaches, and discuss then their QCD evolution, the running driven by an effective charge, from a hadronic scale up to any larger one accessible to experiment.
↳ hep-phnucl-exnucl-thJ.Phys.Conf.Ser.(2020)·9 citations
18
Unified Description of Polarized and Unpolarized Quark Distributions in the Proton
Tianbo Liu🇺🇸 · Raza Sabbir Sufian🇺🇸 · Guy F. de Téramond🇨🇷 · Hans Günter Dosch🇩🇪 · Stanley J. Brodsky🇺🇸 · Alexandre Deur🇺🇸
We propose a unified new approach to describe polarized and unpolarized quark distributions in the proton based on the gauge-gravity correspondence, light-front holography, and the generalized Veneziano model. We find that the spin-dependent quark distributions are uniquely determined in terms of the unpolarized distributions by chirality separation without the introduction of additional free parameters. The predictions are consistent with existing experimental data and agree with perturbative QCD constraints at large longitudinal momentum $x$ . In particular, we predict the sign reversal of the polarized down-quark distribution in the proton at $x = 0.8 \pm 0.03$ , a key property of nucleon substructure which will be tested very soon in upcoming experiments.
↳ hep-phhep-exnucl-exnucl-thPRL(2020)·43 citations
19
Quark model calculations of transition form factors at high photon virtualities
G. Ramalho🇧🇷
We present calculations of $γ^{*} N \to N^{*}$ transition form factors, where $N$ is the nucleon and $N^{*}$ is a nucleon resonance, based on a covariant quark model. Our main focus is at high photon virtualities (large $Q^{2}$ ) where the valence quark degrees of freedom dominate the contributions to the transition form factors and helicity amplitudes. In that regime, the quark model estimates can be compared with the available data, particularly with the Jefferson Lab data at intermediate and large momentum transfer ( $Q^{2} > 2$ GeV $^{2}$ ). The main focus is on the $Δ (1232) 3/ 2^{+}$ , $N (1440) 1/ 2^{+}$ , $N (1535) 1/ 2^{-}$ and $N (1520) 3/ 2^{-}$ resonances, but estimates for other higher mass resonances are also discussed.
↳ hep-phhep-exhep-latnucl-thEPJ Web Conf.(2020)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE