Nuclear Theory·nucl-th

Tuesday·April 4, 2023

16 papers—11 primary·5 cross-listed

12
Flavor hierarchy of parton energy loss in quark-gluon plasma from a Bayesian analysis
Wen-Jing Xing🇨🇳 · Shanshan Cao🇨🇳 · Guang-You Qin🇨🇳
The quenching of light and heavy flavor hadrons in relativistic heavy-ion collisions probes the color and flavor dependences of parton energy loss through a color-deconfined quark-gluon plasma (QGP), and thus reveals the properties of QCD matter at extremely high density and temperature. By combining a next-to-leading order perturbative QCD calculation of parton production, a general ansatz of parton energy loss functions and parton fragmentation functions, we calculate the nuclear modification of various hadron species -- charged hadrons, $D$ mesons and $B$ -decayed $J / ψ$ -- over a wide transverse momentum regime. Comparing our calculations to the experimental data using the Bayesian statistical analysis, we perform a first simultaneous extraction of the energy loss functions of gluons ( $g$ ), light quarks ( $q$ ), charm quarks ( $c$ ) and bottom quarks ( $b$ ) inside the QGP. We find that the average parton energy loss at high energies follows the expected hierarchy of $⟨ Δ E_{g} ⟩ > ⟨ Δ E_{q} ⟩ \sim ⟨ Δ E_{c} ⟩ > ⟨ Δ E_{b} ⟩$ , while the parton energy loss distribution can further test the QCD calculations of parton interaction with the dense nuclear matter. We also find that the reduction of experimental uncertainties can significantly improve the precision of the extracted parton energy loss functions inside the QGP.
↳ hep-phhep-exnucl-exnucl-thPLB(2024)·19 citations
13
Quantum free-streaming: out of equilibrium expansion for the free scalar fields
Leonardo Tinti🇵🇱
The collisionless Boltzmann equation, also called free-streaming, is a convenient approximation. It is rather simple to implement numerically, and and it is effective at reducing the irregularities of rough initial conditions. It can be obtained as a small $ℏ$ limit from a free scalar quantum field. Namely, by neglecting the $ℏ^{2}$ term in the dynamical evolution of the Wigner distribution, the quantum precursor of the distribution function. In this work it is presented the general form for the exact solutions of the Wigner distribution, for a scalar field undergoing a $(1 + 1)$ -dimensional expansion. Namely, with the symmetry constraint of rotation and translation invariance in the transverse plane. It is very different from the (on-shell) free-streaming of classical particles. It is shown how to recognize the classical, $ℏ \to 0$ , limit from the general form. The numerical analysis for a specific example shows very large quantum corrections to the classical free-streaming.
↳ hep-phnucl-thPRD(2023)·7 citations
14
Hadron Structure using Continuum Schwinger Function Methods
Craig D. Roberts🇨🇳
The vast bulk of visible mass emerges from nonperturbative dynamics within quantum chromodynamics (QCD) -- the strong interaction sector of the Standard Model. The past decade has revealed the three pillars that support this emergent hadron mass (EHM); namely, a nonzero gluon mass-scale, a process-independent effective charge, and dressed-quarks with constituent-like masses. Theory is now working to expose their manifold and diverse expressions in hadron observables and highlighting the types of measurements that can be made in order to validate the paradigm. In sketching some of these developments, this discussion stresses the role of EHM in forming nucleon electroweak structure and the wave functions of excited baryons through the generation of dynamical diquark correlations; producing and constraining the dilation of the leading-twist pion distribution amplitude; shaping pion and nucleon parton distribution functions -- valence, glue and sea, including the antisymmetry of antimatter; and moulding pion and proton charge and mass distributions.
↳ hep-phhep-exhep-latnucl-ex+1Few Body Syst.(2023)·10 citations
15
Sterile neutrino searches with reactor antineutrinos using coherent neutrino-nucleus scattering experiments
S. P. Behera · D. K. Mishra · P. K. Netrakanti · R. Sehgal · R. Dey · V. Jha
We present an analysis on the sensitivity to the active-sterile neutrino mixing with Germanium (Ge) and Silicon (Si) detectors in the context of the proposed coherent elastic neutrino-nucleus experiment in India. The study has been carried out with 3 (active) $+$ 1 (sterile) neutrino oscillation model. It is observed that the measurements that can be carried out with the Ge detector exhibit better sensitivity to the active-sterile neutrino mixing as compared to the Si detector. Both detectors are able to exclude most of the anomaly regions observed by the GALLIUM experiment. The Ge detector with mass 10 kg, can observe the active-sterile neutrino oscillation at 95 $%$ confidence level, provided that $sin^{2} 2 θ_{14} \geq 0.09$ at $Δ m_{41}^{2}$ = 1.0 eV $^{2}$ for an exposure of 1-yr. At higher values of $Δ m_{41}^{2}$ , a better sensitivity is obtained at a short baseline. It is also found that the threshold as well as resolution of the detectors play a crucial role on the measurements of active-sterile neutrino mixing parameters.
↳ hep-phhep-exnucl-thPRD(2023)·6 citations
16
One-loop matching of $C P$ -odd four-quark operators to the gradient-flow scheme
Jona Bühler🇨🇭 · Peter Stoffer🇨🇭
The translation of experimental limits on the neutron electric dipole moment into constraints on heavy $C P$ -violating physics beyond the Standard Model requires knowledge about non-perturbative matrix elements of effective operators, which ideally should be computed in lattice QCD. However, this necessitates a matching calculation as an interface to the effective field theory framework, which is based on dimensional regularization and renormalization by minimal subtraction. We calculate the one-loop matching between the gradient-flow and minimal-subtraction schemes for the $C P$ -violating four-quark operators contributing to the neutron electric dipole moment. The gradient flow is a modern regularization-independent scheme amenable to lattice computations that promises, e.g., better control over power divergences than traditional momentum-subtraction schemes. Our results extend previous work on dimension-five operators and provide a necessary ingredient for future lattice-QCD computations of the contribution of four-quark operators to the neutron electric dipole moment.
↳ hep-lathep-exhep-phnucl-thJHEP(2023)·15 citations

Affiliations

first authorsco-authorsvia INSPIRE

Flavor hierarchy of parton energy loss in quark-gluon plasma from a Bayesian analysis

Quantum free-streaming: out of equilibrium expansion for the free scalar fields

Hadron Structure using Continuum Schwinger Function Methods

Sterile neutrino searches with reactor antineutrinos using coherent neutrino-nucleus scattering experiments

One-loop matching of CP-odd four-quark operators to the gradient-flow scheme

Affiliations

One-loop matching of $C P$ -odd four-quark operators to the gradient-flow scheme