Nuclear Theory·nucl-th

Thursday·June 30, 2022

11 papers—5 primary·6 cross-listed

06
[Submitted on 24 Jun 2022] (cross-list from hep-ph)
Towards Powerful Probes of Neutrino Self-Interactions in Supernovae
Po-Wen Chang🇺🇸 · Ivan Esteban🇺🇸 · John F. Beacom🇺🇸 · Todd A. Thompson🇺🇸 · Christopher M. Hirata🇺🇸
Neutrinos remain mysterious. As an example, enhanced self-interactions ( $ν$ SI), which would have broad implications, are allowed. At the high neutrino densities within core-collapse supernovae, $ν$ SI should be important, but robust observables have been lacking. We show that $ν$ SI make neutrinos form a tightly coupled fluid that expands under relativistic hydrodynamics. The outflow becomes either a burst or a steady-state wind; which occurs here is uncertain. Though the diffusive environment where neutrinos are produced may make a wind more likely, further work is needed to determine when each case is realized. In the burst-outflow case, $ν$ SI increase the duration of the neutrino signal, and even a simple analysis of SN 1987A data has powerful sensitivity. For the wind-outflow case, we outline several promising ideas that may lead to new observables. Combined, these results are important steps towards solving the 35-year-old puzzle of how $ν$ SI affect supernovae.
Comments:
5+19 pages, 4+14 figures. Accepted for publication in Phys.Rev.Lett. Match the version to be published: minor revisions for clarity; moved discussion about supernova neutrino properties to Supplemental Material C; updated references
Subjects:
High Energy Physics — Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2206.12426 [pdf]
PRL(2023)·66 citations
07
[Submitted on 28 Jun 2022] (cross-list from hep-ph)
Effect of thermal gluon absorption and medium fluctuations on heavy flavour nuclear modification factor at RHIC and LHC energies
Ashik Ikbal Sheikh🇺🇸
The presence of thermal gluons reduces the stimulated gluon emission off a heavy quark propagating in the quark-gluon plasma (QGP) while absorption causes reduction of the radiative energy loss. On the other hand, the chromo-electromagnetic field fluctuations present in the QGP lead to collisional energy gain of the heavy quark. The net effect of the thermal gluon absorption and field fluctuations is a reduction of the total energy loss of the heavy quark, prominent at the lower momenta. We consider both kind of the energy gains along with the usual losses, and compute the nuclear modification factor ( $R_{AA}$ ) of heavy mesons, viz., $D$ and $B$ mesons. The calculations have been compared with the experimental measurements in Au-Au collisions at $s_{N N} = 200$ GeV from STAR and PHENIX experiments at the RHIC and Pb-Pb collisions at $s_{N N} = 2.76$ TeV and $5.02$ TeV from CMS and ALICE experiments at the LHC. We find a significant effect of the total energy gain due to thermal gluon absorption and field fluctuations on heavy flavour suppression, especially at the lower transverse momenta.
Comments:
Published in EPJA
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2206.14243 [pdf]
EPJA(2021)·1 citation
08
[Submitted on 29 Jun 2022] (cross-list from hep-ph)
Quantum Chromodynamics Resolution of the ATOMKI Anomaly in $^{4} He$ Nuclear Transitions
Valery Kubarovsky🇺🇸 · Jennifer Rittenhouse West🇺🇸 · Stanley J. Brodsky🇺🇸
Observations of anomalous angular correlations in electron-positron pairs produced from excited states of $^{4}$ He, $^{8}$ Be and $^{12}$ C nuclei have been suggested as due to the creation and subsequent decay of a new light particle of mass $\sim$ 17 MeV. In this work, we investigate the possibility that the source of the observed signals is a set of new excitation channels created by the 12-quark hidden-color Fock state within the $^{4} He$ nuclear wavefunction dubbed the ``hexadiquark.'' We calculate the invariant $e^{+} e^{-}$ mass spectrum for the electromagnetic transition from a new excitation of $^{4}$ He, estimating its differential and total decay width. We find that we can fit the shape of the anomalous signal with the QCD Fock state at excitation energy $E^{*} = 17.9 \pm 1$ MeV and a Gaussian form factor for the electromagnetic decay. We address the physical issues with the fit parameters using properties of the hexadiquark state, in particular the three weakly repulsive $6_{C}$ interactions of $SU (3)_{C}$ between diquark pairs. Experimental tests of our model are described in detail. In light of this work, we emphasize the need for independent experimental confirmation or refutation of the ATOMKI results as well as dedicated experiments to search for the proposed new excitations of $^{4} He$ and other $α$ -cluster nuclei.
Comments:
Published version, Physical Review C 2025
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2206.14441 [pdf]
PRC(2025)·16 citations
09
[Submitted on 29 Jun 2022] (cross-list from hep-ph)
Theoretical study on the contributions of $ω$ meson to the $X (3872) \to J / ψ π^{+} π^{-}$ and $J / ψ π^{+} π^{-} π^{0}$ decays
Hao-Nan Wang🇨🇳 · Qian Wang🇨🇳 · Ju-Jun Xie🇨🇳
With the newly measurements of $X (3872) \to J / ψ π^{+} π^{-}$ from LHCb Collaboration, in addition to the dominant contribution from the $ρ^{0}$ meson, we perform a theoretical study on the contribution of $ω$ meson in the $X (3872) \to J / ψ π^{+} π^{-}$ and $X (3872) \to J / ψ π^{+} π^{-} π^{0}$ processes. It is found that the recent experimental measurements on the $π^{+} π^{-}$ invariant mass distributions can be well reproduced, and the ratio of the couplings between $X (3872) \to J / ψ ρ^{0}$ and $X (3872) \to J / ψ ω$ is also evaluated. Within the parameters extracted from the $π^{+} π^{-}$ invariant mass distributions of the $X (3872) \to J / ψ π^{+} π^{-}$ process, the branching fractions of the $X (3872) \to J / ψ ω$ channel relative to that of the $X (3872) \to J / ψ π^{+} π^{-} π^{0}$ channel and the $π^{+} π^{-} π^{0}$ invariant mass distributions of the $X (3872) \to J / ψ π^{+} π^{-} π^{0}$ decay are calculated, which gives a hint for the further high-statistic experiment.
Comments:
8 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2206.14456 [pdf]
PRD(2022)·7 citations
10
[Submitted on 29 Jun 2022] (cross-list from hep-lat)
Spectral and transport properties from lattice QCD
Olaf Kaczmarek🇩🇪 · Hai-Tao Shu🇩🇪
In these lecture notes we will discuss recent progress in extracting spectral and transport properties from lattice QCD. We will focus on results of probes of the thermal QCD medium as well as transport coefficients which are important ingredients for hydrodynamic and transport models that describe the evolution of the produced medium. These include electromagnetic probes, like the rates of emitted photons and dileptons, quarkonium spectral functions as well as transport coefficients like the electrical conductivity or heavy flavor diffusion coefficients of the quark gluon plasma (QGP). All these real time quantities are encoded in the vector meson spectral function. A direct determination of the spectral functions is not possible in Euclidean lattice QCD calculations but they can be analytically continued from imaginary to real time. Therefore it is possible to relate the spectral function to the corresponding Euclidean correlation functions. In the following sections we will discuss the procedure to determine the required correlation functions and the extraction of the spectral functions from lattice QCD correlators. We will illustrate the concepts and methods to obtain spectral functions and related physical observables from continuum extrapolated correlation functions. We will focus here on results obtained from continuum extrapolated lattice correlation functions, which requires large and fine lattices, which so far was only possible in quenched approximation. We will only give a brief introduction to lattice QCD and refer to the textbooks [1,2,3,4] and lecture notes [5] for more detailed introductions to lattice field theory. For the topics addressed in this lecture note we also like to refer to the overview articles on QCD thermodynamics and the QCD phase transition [5,6,7] and quarkonium in extreme conditions [8].
Comments:
Lectures delivered at the 53rd Karpacz Winter School of Theoretical Physics, February 26th - March 4th, 2017, Karpacz, Poland; submitted to Lecture Notes in Physics (LNP, volume 999), ISBN: 978-3-030-95490-1
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2206.14676 [pdf]
Lect.Notes Phys.(2022)·13 citations
11
[Submitted on 29 Jun 2022] (cross-list from cond-mat.other)
The role of electron polarization on nuclear spin diffusion
Alessandro Chessari · Samuel F. Cousin · Sami Jannin · Quentin Stern
Dynamic nuclear polarization (DNP) is capable of boosting signals in nuclear magnetic resonance by orders of magnitude by creating out-of-equilibrium nuclear spin polarization. The diffusion of nuclear spin polarization in the vicinity of paramagnetic dopants is a crucial step for DNP and remains yet not well understood. In this Letter, we show that the polarization of the electron spin controls the rate of proton spin diffusion in a DNP sample at 1.2 K and 7 T; at increasingly high electron polarization, spin diffusion vanishes. We rationalize our results using a 2 nucleus - 1 electron model and Lindblad s Master equation, which generalizes preexisting models in the literature and qualitatively accounts for the experimental observed spin diffusion dynamics.
Comments:
Main text: 6 pages, 3 figures Supplement: 9 pages, 4 figures
Subjects:
cond-mat.other (cond-mat.other); Nuclear Theory (nucl-th)
arXiv:
2206.14771 [pdf]
PRB(2023)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE

Towards Powerful Probes of Neutrino Self-Interactions in Supernovae

Effect of thermal gluon absorption and medium fluctuations on heavy flavour nuclear modification factor at RHIC and LHC energies

Quantum Chromodynamics Resolution of the ATOMKI Anomaly in 4He Nuclear Transitions

Theoretical study on the contributions of ω meson to the X(3872)→J/ψπ+π− and J/ψπ+π−π0 decays

Spectral and transport properties from lattice QCD

The role of electron polarization on nuclear spin diffusion

Affiliations

Quantum Chromodynamics Resolution of the ATOMKI Anomaly in $^{4} He$ Nuclear Transitions

Theoretical study on the contributions of $ω$ meson to the $X (3872) \to J / ψ π^{+} π^{-}$ and $J / ψ π^{+} π^{-} π^{0}$ decays