Nuclear Theory·nucl-th

Friday·October 29, 2021

20 papers—6 primary·14 cross-listed

07
[Submitted on 25 Oct 2021] (cross-list from hep-ph)
Disentangling Jet Modification in Jet Simulations and in Z+Jet Data
Jasmine Brewer🇨🇭 · Quinn Brodsky🇺🇸 · Krishna Rajagopal🇺🇸
We study the impact of selection biases on jet structure and substructure observables and separate these effects from effects caused by jet quenching. We use the angular separation $Δ R$ of the hardest splitting in a jet as the primary example observable. We first conduct a simplified Monte Carlo study in which it is possible to identify the same jet after quenching in a heavy ion collision and as it would have been if it had formed in vacuum. We select a sample of jets by placing a cut on their quenched $p_{T}$ and, as is possible only in a Monte Carlo study, compare to the same jets unquenched, and see that the $Δ R$ distribution seems to be unmodified. However, if we select a sample of jets formed in vacuum by placing a cut on their unquenched $p_{T}$ and compare to those same jets after quenching, we see a significant enhancement in the number of jets with large $Δ R$ , primarily due to the soft particles in the jet that originate from the wake in the droplet of quark-gluon plasma excited by the parton shower. We confirm that the jets contributing to this enhancement are those jets which lost the most energy, which were not included in the sample selected after quenching; jets selected after quenching are those which lose a small fraction of their energy. Next, we employ a method that is available to experimentalists: in a sample of jets with a recoiling $Z$ boson, we show that selecting jets based on the jet $p_{T}$ after quenching yields a $Δ R$ distribution that appears unmodified while selecting a sample of jets produced in association with a $Z$ boson whose (unmodified) $p_{T}$ is above some cut yields a significant enhancement in the number of jets with large $Δ R$ . We again confirm that this is due to particles from the wake, and that the jets contributing to this enhancement are those which have lost a significant fraction of their energy.
Comments:
16 pages, 8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2110.13159 [pdf]
JHEP(2022)·50 citations
08
[Submitted on 27 Oct 2021] (cross-list from hep-ph)
Electromagnetic form factors of baryons in nuclear medium
G. Ramalho🇧🇷 · K. Tsushima🇧🇷 · J.P.B.C. de Melo🇧🇷
The electromagnetic structure of the baryons is modified in the nuclear medium. The modifications can be inferred from the comparison between the electromagnetic form factors in medium with the respective form factor in vacuum. Of particular interest is the ratio between the electric and magnetic form factors in medium ( $G_{E}^{*} / G_{M}^{*}$ ) and vacuum ( $G_{E} / G_{M}$ ) of the octet baryon. The deviation of the double ratios ( $G_{E}^{*} / G_{M}^{*}) / (G_{E} / G_{M})$ from unity measures the impact of the medium modification of the electromagnetic structure in a nuclear medium. Measurements of the double ratios $(G_{E}^{*} / G_{M}^{*}) / (G_{E} / G_{M})$ for different nuclear densities may become available in a near future using the polarization-transfer method developed at Jefferson Lab. We present estimates of the double ratios of octet baryons based on a covariant constituent quark model, which takes into account pion cloud excitations of the baryon cores,for different nuclear densities. Our results manifest different features, namely, enhancement or quenching depending on the baryon flavor content.
Comments:
Proceedings of conference PANIC 2021. 5 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2110.14107 [pdf]
PoS(2022)·1 citation
09
[Submitted on 27 Oct 2021] (cross-list from hep-lat)
Regularisation in Nonperturbative Extensions of Effective Field Theory
Curtis D. Abell🇦🇺 · Derek B. Leinweber🇦🇺 · Anthony W. Thomas🇦🇺 · Jia-Jun Wu🇨🇳
The process of renormalisation in nonperturbative Hamiltonian Effective Field Theory (HEFT) is examined in the $Δ$ -resonance scattering channel. As an extension of effective field theory incorporating the Lüscher formalism, HEFT provides a bridge between the infinite-volume scattering data of experiment and the finite-volume spectrum of energy eigenstates in lattice QCD. HEFT also provides phenomenological insight into the basis-state composition of the finite-volume eigenstates via the state eigenvectors. The Hamiltonian matrix is made finite through the introduction of finite-range regularisation. The extent to which the established features of this regularisation scheme survive in HEFT is examined. In a single-channel $π N$ analysis, fits to experimental phase shifts withstand large variations in the regularisation parameter, $Λ$ , providing an opportunity to explore the sensitivity of the finite-volume spectrum and state composition on the regulator. While the Lüscher formalism ensures the eigenvalues are insensitive to $Λ$ variation in the single-channel case, the eigenstate composition varies with $Λ$ ; the admission of short distance interactions diminishes single-particle contributions to the states. In the two-channel $π N$ , $π Δ$ analysis, $Λ$ is restricted to a small range by the experimental data. Here the inelasticity is particularly sensitive to variations in $Λ$ and its associated parameter set. This sensitivity is also manifest in the finite-volume spectrum for states near the opening of the $π Δ$ scattering channel. Finally, HEFT has the unique ability to describe the quark-mass dependence of the finite-volume eigenstates. The robust nature of this capability is presented and used to confront current state-of-the-art lattice QCD calculations.
Comments:
21 pages, 22 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2110.14113 [pdf]
PRD(2022)·21 citations
10
[Submitted on 27 Oct 2021] (cross-list from hep-ph)
Incomplete electromagnetic response of hot QCD matter
Zeyan Wang🇨🇳 · Jiaxing Zhao🇨🇳 · Carsten Greiner🇩🇪 · Zhe Xu🇨🇳 · Pengfei Zhuang🇨🇳
The electromagnetic response of hot QCD matter to decaying external magnetic fields is investigated. We examine the validity of Ohm's law and find that the induced electric current increases from zero and relaxes towards the value from Ohm's law. The relaxation time is larger than the lifetime of the external magnetic field for the QCD matter in relativistic heavy-ion collisions. The lower than expected electric current significantly suppresses the induced magnetic field and makes the electromagnetic response incomplete. We demonstrate the incomplete electromagnetic response of hot QCD matter by calculations employing the parton transport model combined with the solution of Maxwell's equations. Our results show a strong suppression by two orders of magnitude in the magnetic field, relatively to calculations assuming the validity of Ohm's law. This may undermine experimental efforts to measure magnetic-field-related effects in heavy-ion collisions.
Comments:
6 pages, 4 figures; text modified, references updated, results unchanged; published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2110.14302 [pdf]
PRC(2022)·57 citations
11
[Submitted on 27 Oct 2021] (cross-list from hep-ph)
The importance of multiple scatterings in medium-induced gluon radiation
Carlota Andres🇫🇷 · Fabio Dominguez🇪🇸 · Marcos Gonzalez Martinez🇪🇸
In this work we disentangle the underlying physical picture of the in-medium gluon radiation process across its different energy regimes by comparing the recently obtained fully-resummed -- without any further approximations -- BDMPS-Z in-medium emission spectrum with the extensively used analytical approaches. We observe that in the high-energy regime the radiation process is dominated by a single hard scattering, while in the intermediate-energy region coherence effects among multiple scatterings are crucial. Finally, we prove that in the low-energy regime the dynamics is again controlled by a single scattering but where one must include a suppression factor accounting for the probability of not having any further scatterings.
Comments:
Proceedings of ISMD2021
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2110.14384 [pdf]
SciPost Phys.Proc.(2022)·0 citations
12
[Submitted on 27 Oct 2021] (cross-list from hep-lat)
Gluon Parton Distribution of the Pion and Nucleon from Lattice QCD
Zhouyou Fan🇺🇸 · Huey-Wen Lin🇺🇸
We present the $x$ -dependent nucleon and pion gluon distribution from lattice QCD using the pseudo-PDF approach, on lattice ensembles with $2 + 1 + 1$ flavors of highly improved staggered quarks (HISQ), generated by MILC Collaboration. We use clover fermions for the valence action and momentum smearing to achieve pion boost momentum up to 2.56~GeV on three lattice spacings $a \approx 0.9, 0.12$ and 0.15~fm and three pion masses $M_{π} \approx 220$ , 310 and 690~MeV. We compare our pion and preliminary nucleon gluon results with the determination by global fits.
Comments:
9 pages, 7 figures, The 38th Annual International Symposium on Lattice Field Theory - LATTICE2021
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2110.14471 [pdf]
PoS(2022)·5 citations
13
[Submitted on 27 Oct 2021] (cross-list from nucl-ex)
Improved Nuclear Physics Near $A = 61$ Refines Urca Neutrino Luminosities in Accreted Neutron Star Crusts
Zach Meisel🇺🇸 · Alec Hamaker🇺🇸 · G. Bollen🇺🇸 · B.A. Brown🇺🇸 · M. Eibach🇩🇪 · K. Gulyuz🇺🇸 · C. Izzo🇺🇸 · C. Langer🇩🇪 · F. Montes🇺🇸 · W.-J Ong🇺🇸 · D. Puentes🇺🇸 · M. Redshaw🇺🇸 and 7 other authors
We performed a Penning trap mass measurement of $^{61} Zn$ at the National Superconducting Cyclotron Laboratory and NuShellX calculations of the $^{61} Zn$ and $^{62} Ga$ structure using the GXPF1A Hamiltonian to obtain improved estimates of the $^{61} Zn (p, γ)^{62} Ga$ and $^{60} Cu (p, γ)^{61} Zn$ reaction rates. Surveying astrophysical conditions for type-I X-ray bursts with the code MESA, implementing our improved reaction rates, and taking into account updated nuclear masses for $^{61} V$ and $^{61} Cr$ from the recent literature, we refine the neutrino luminosity from the important mass number $A = 61$ urca cooling source in accreted neutron star crusts. This improves our understanding of the thermal barrier between deep heating in the crust and the shallow depths where extra heat is needed to explain X-ray superbursts, as well as the expected signature of crust urca neutrino emission in light curves of cooling transients.
Comments:
Submitted
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2110.14558 [pdf]
PRC(2022)·6 citations
14
[Submitted on 27 Oct 2021] (cross-list from hep-ex)
Implementation of the CRPA model in the GENIE event generator and analysis of nuclear effects in low-energy transfer neutrino-nucleus interactions
S. Dolan🇨🇭 · A. Nikolakopoulos🇧🇪 · O. Page🇬🇧 · S. Gardiner🇺🇸 · N. Jachowicz🇧🇪 · V. Pandey🇺🇸
We present the implementation and validation of the Hartree-Fock continuum random phase approximation (HF-CRPA) model in the GENIE neutrino-nucleus interaction event generator and a comparison of the subsequent predictions to experimental measurements of lepton kinematics from interactions with no mesons in the final state. These predictions are also compared to those of other models available in GENIE. It is shown that, with respect to these models, HF-CRPA predicts a significantly different evolution of the cross section when moving between different interaction targets, when considering incoming anti-neutrinos compared to neutrinos and when changing neutrino energies. These differences are most apparent for interactions with low energy and momentum transfer. It is also clear that the impact of nucleon correlations within the HF-CRPA framework is very different than in GENIE's standard implementation of RPA corrections. Since many neutrino oscillation experiments rely on their input model to extrapolate between targets, flavours, and neutrino energies, the newly implemented HF-CRPA model provides a useful means to verify that such differences between models are appropriately covered in oscillation analysis systematic error budgets.
Comments:
14 pages, 12 figures. Version concurrent with published paper. Metadata updated
Subjects:
High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2110.14601 [pdf]
PRD(2022)·26 citations
15
[Submitted on 27 Oct 2021] (cross-list from hep-ph)
Heavy quarks in the early stage of high energy nuclear collisions at RHIC and LHC: Brownian motion versus diffusion in the evolving Glasma
Pooja🇮🇳 · Santosh K. Das🇮🇳 · Lucia Oliva🇮🇹 · Marco Ruggieri🇨🇳
We study the transverse momentum, $p_{T}$ , broadening of charm and beauty quarks in the early stage of high energy nuclear collisions. We aim to compare the diffusion in the evolving Glasma fields with that of a standard, Markovian-Brownian motion in a thermalized medium with the same energy density of the Glasma fields. The Brownian motion is studied via Langevin equations with diffusion coefficients computed within perturbative Quantum Chromodynamics. We find that for small values of the saturation scale, $Q_{s}$ , the average $p_{T}$ broadening in the two motions is comparable, that suggests that the diffusion coefficient in the evolving Glasma fields is in agreement with the perturbative calculations. On the other hand, for large $Q_{s}$ the $p_{T}$ broadening in the Langevin motion is smaller than that in the Glasma fields. This difference can be related to the fact that heavy quarks in the latter system experience diffusion in strong, coherent gluon fields that leads to a faster momentum broadening due to memory, or equivalently to a strong correlation in the transverse plane.
Comments:
11 pages, 10+1 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2110.14610 [pdf]
Eur.Phys.J.Plus(2022)·42 citations
16
[Submitted on 27 Oct 2021] (cross-list from hep-ph)
Jet Broadening in the Opacity and Twist Expansions
Hannah Clayton🇿🇦 · Matthew D. Sievert🇺🇸 · W. A. Horowitz🇿🇦
We compute the in-medium jet broadening $⟨ p_{⊥}^{2} ⟩$ to leading order in energy in the opacity expansion. At leading order in $α_{s}$ the elastic energy loss gives a jet broadening that grows with $ln E$ . The next-to-leading order in $α_{s}$ result is a jet narrowing, due to destructive LPM interference effects, that grows with $ln^{2} E$ . We find that in the opacity expansion the jet broadening asymptotics are -- unlike for the mean energy loss -- extremely sensitive to the correct treatment of the finite kinematics of the problem; integrating over all emitted gluon transverse momenta leads to a prediction of jet broadening rather than narrowing. We compare the asymptotics from the opacity expansion to a recent twist-4 derivation of $⟨ p_{⊥}^{2} ⟩$ and find a qualitative disagreement: the twist-4 derivation predicts a jet broadening rather than a narrowing. Comparison with current jet measurements cannot distinguish between the broadening or narrowing predictions. We comment on the origin of the difference between the opacity expansion and twist-4 results.
Comments:
23 pages, 17 figures. v2 is consistent with the published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2110.14737 [pdf]
EPJC(2022)·11 citations
17
[Submitted on 27 Oct 2021] (cross-list from hep-lat)
QCD thermodynamics at non-zero isospin asymmetry
Bastian B. Brandt🇩🇪 · Francesca Cuteri🇩🇪 · Gergely Endrodi🇩🇪
We study the thermodynamic properties of QCD at nonzero isospin chemical potential using improved staggered quarks at physical quark masses. In particular, we discuss the determination of the equation of state at zero and nonzero temperatures and show results. Using the results for the isospin density $n_{I}$ , we also determine the phase diagram in the $(n_{I}, T)$ -plane.
Comments:
9 pages, 9 figures, contribution to the 38th International Symposium on Lattice Field Theory (LATTICE21); v2: corrected references, added ancillary data files and plotting scripts
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2110.14750 [pdf]
PoS(2022)·12 citations
18
[Submitted on 27 Oct 2021] (cross-list from hep-ph)
Momentum-Current Gravitational Multipoles of Hadrons
Xiangdong Ji🇺🇸 · Yizhuang Liu🇵🇱
We study multipole expansion of the momentum currents in hadrons, with three series $S^{(J)}$ , $T ~^{(J)}$ , and $T^{(J)}$ , in connection with the gravitational fields generated nearby. The momentum currents are related to their energy-momentum form factors, which in principle can be probed through processes like deeply-virtual Compton scattering currently studied at JLab 12 GeV facility and future Electron Ion Collider. We define the leading momentum-current multipoles, tensor monopole $τ$ ( $T 0$ ) and scalar quadrupole $σ^^{ij}$ ( $S 2$ ) moments, relating the former to the so-called $D$ -term in the literature. We calculate the momentum current distribution in hydrogen atom and its monopole moment in the basic unit of $τ_{0} = ℏ^{2} /4 M$ , showing that the sign of $D$ -term has little to do with mechanical stability. The momentum current distribution also strongly modifies the static gravitational field inside hadrons.
Comments:
12 pages, 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2110.14781 [pdf]
PRD(2022)·49 citations
19
[Submitted on 28 Oct 2021] (cross-list from cond-mat.quant-gas)
Nonlinear Klein-Gordon equation and the Bose-Einstein condensation
E. Megias🇪🇸 · M.J. Teixeira🇧🇷 · V.S. Timóteo🇧🇷 · A. Deppman🇧🇷
The interest in the Klein-Gordon equation with different potentials has increased in recent years due to its possible applications in Cosmology, Hadron Physics and High-Energy Physics. In this work we investigate the solutions of the Klein-Gordon equation for bosons under the influence of an external potential by using the Feshbach-Villars method. We present detailed results for two cases: the Coulombic potential and the harmonic potential. For the latter case, we studied the effects of self-interacting particles by adopting a mean-field approach. We show that our results converge smoothly to the solution of the Schrödinger equation for the same systems as the relativistic effects diminish.
Comments:
8 pages, 3 figures; v2 typos corrected, added references, extended discussion. It matches the version published in The European Physical Journal Plus
Subjects:
Quantum Gases (cond-mat.quant-gas); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2110.14939 [pdf]
Eur.Phys.J.Plus(2022)·1 citation
20
[Submitted on 28 Oct 2021] (cross-list from hep-ph)
A novel event generator for the automated simulation of neutrino scattering
Joshua Isaacson🇺🇸 · Stefan Höche🇺🇸 · Diego Lopez Gutierrez🇺🇸 · Noemi Rocco🇺🇸
An event generation framework is presented that enables the automatic simulation of events for next-generation neutrino experiments in the Standard Model or extensions thereof. The new generator combines the calculation of the leptonic current based on an automated matrix element generator, and the computation of the hadronic current based on a state-of-the-art nuclear physics model. The approach is validated in Standard-Model simulations for electron scattering and neutrino scattering. Furthermore, the first fully-differential neutrino trident production results are shown in the quasielastic region.
Comments:
13 pages, 8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2110.15319 [pdf]
PRD(2022)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE