Nuclear Theory·nucl-th

Thursday·July 20, 2023

13 papers—5 primary·8 cross-listed

06
[Submitted on 17 Jul 2023] (cross-list from hep-ph)
Repercussions of the Peccei-Quinn axion on QCD
Gerrit Schierholz🇩🇪
The axion, originally postulated by Peccei and Quinn to solve the strong CP problem, has become of great interest in particle and astroparticle phenomenology. Yet it has a problem. It is widely assumed that the axion leaves the nonperturbative features of QCD unscathed. This is, however, not the case. On the contrary, the axion extension is found to be in conflict with seminal results on the low-energy properties of QCD. The key is that the anomalous coupling of the axion to the gauge bosons can be integrated out, leaving behind a path integral over topologically trivial gauge potentials.
Comments:
11 pages, expanded by new findings, including two figures; matches published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2307.08310 [pdf]
Mod.Phys.Lett.A(2025)·3 citations
07
[Submitted on 18 Jul 2023] (cross-list from hep-ph)
Orbital Angular Momentum at Small $x$
Brandon Manley🇺🇸
We revisit the problem of the small Bjorken- $x$ asymptotics of the quark and gluon orbital angular momentum (OAM) distributions in the proton utilizing the revised formalism for small- $x$ helicity evolution derived recently in a paper by Cougoulic, Kovchegov, Tarasov, and Tawabutr. We relate the quark and gluon OAM distributions at small $x$ to the polarized dipole amplitudes and their (first) impact-parameter moments. To obtain the $x$ -dependence of the OAM distributions, we derive novel small- $x$ evolution equations for the impact-parameter moments of the polarized dipole amplitudes in the double-logarithmic approximation (summing powers of $α_{s} ln^{2} (1/ x)$ with $α_{s}$ the strong coupling constant). We solve these evolution equations numerically and extract the large- $N_{c}$ , small- $x$ asymptotics of the quark and gluon OAM distributions, which we determine to be \[ L_{q+\bar{q}}(x, Q^2) \sim L_{G}(x,Q^2) \sim \Delta \Sigma(x, Q^2) \sim \Delta G(x,Q^2) \sim \left(\frac{1}{x}\right)^{3.66 \, \sqrt{\frac{\alpha_s N_c}{2\pi}}},\] in agreement with an earlier work by Boussarie, Hatta, and Yuan within the precision of our numerical evaluation (here $N_{c}$ is the number of quark colors). We also investigate the ratios of the quark and gluon OAM distributions to their helicity distribution counterparts in the small- $x$ region.
Comments:
Presented at DIS2023: XXX International Workshop on Deep-Inelastic Scattering and Related Subjects, Michigan State University, USA, 27-31 March 2023
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2307.09544 [pdf]
1 citation
08
[Submitted on 13 Jul 2023] (cross-list from math.AP)
Local well-posedness and singularity formation in non-Newtonian compressible fluids
Ariel Lerman · Marcelo M. Disconzi · Jorge Noronha
We investigate the initial value problem of a very general class of $3 + 1$ non-Newtonian compressible fluids in which the viscous stress tensor with shear and bulk viscosity relaxes to its Navier-Stokes values. These fluids correspond to the non-relativistic limit of well-known Israel-Stewart-like theories used in the relativistic fluid dynamic simulations of high-energy nuclear and astrophysical systems. After establishing the local well-posedness of the Cauchy problem, we show for the first time in the literature that there exists a large class of initial data for which the corresponding evolution breaks down in finite time due to the formation of singularities. This implies that a large class of non-Newtonian fluids do not have finite solutions defined at all times.
Comments:
15 pages, revised version accepted for publication
Subjects:
math.AP (math.AP); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th); Fluid Dynamics (physics.flu-dyn)
arXiv:
2307.09611 [pdf]
J.Phys.A(2024)·3 citations
09
[Submitted on 18 Jul 2023] (cross-list from hep-ph)
Multiscale evolution of heavy flavor in the QGP
G. Vujanovic · A. Angerami · R. Arora · S. A. Bass · S. Cao · Y. Chen · T. Dai · L. Du · R. Ehlers · H. Elfner · W. Fan · R. J. Fries and 43 other authors
Shower development dynamics for a jet traveling through the quark-gluon plasma (QGP) is a multiscale process, where the heavy flavor mass is an important scale. During the high virtuality portion of the jet evolution in the QGP, emission of gluons from a heavy flavor is modified owing to heavy quark mass. Medium-induced radiation of heavy flavor is sensitive to microscopic processes (e.g. diffusion), whose virtuality dependence is phenomenologically explored in this study. In the lower virtuality part of shower evolution, i.e. when the mass is comparable to the virtuality of the parton, scattering and radiation processes of heavy quarks differ from light quarks. The effects of these mechanisms on shower development in heavy flavor tagged showers in the QGP is explored here. Furthermore, this multiscale study examines dynamical pair production of heavy flavor (via virtual gluon splittings) and their subsequent evolution in the QGP, which is not possible otherwise. A realistic event-by-event simulation is performed using the JETSCAPE framework. Energy-momentum exchange with the medium proceeds using a weak coupling recoil approach. Using leading hadron and open heavy flavor observables, differences in heavy versus light quark energy-loss mechanisms are explored, while the importance of heavy flavor pair production is highlighted along with future directions to study.
Comments:
6 pages, 3 figures, contribution to the Hard Probes 2023 proceedings
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2307.09640 [pdf]
PoS(2024)·0 citations
10
[Submitted on 18 Jul 2023] (cross-list from hep-ph)
A new metric improving Bayesian calibration of a multistage approach studying hadron and inclusive jet suppression
W. Fan🇺🇸 · G. Vujanovic🇺🇸 · S. A. Bass🇺🇸 · A. Angerami🇺🇸 · R. Arora🇺🇸 · S. Cao🇨🇳 · Y. Chen🇺🇸 · T. Dai🇺🇸 · L. Du🇨🇦 · R. Ehlers🇺🇸 · H. Elfner🇩🇪 · R. J. Fries🇺🇸 and 43 other authors
We study parton energy-momentum exchange with the quark gluon plasma (QGP) within a multistage approach composed of in-medium DGLAP evolution at high virtuality, and (linearized) Boltzmann Transport formalism at lower virtuality. This multistage simulation is then calibrated in comparison with high $p_{T}$ charged hadrons, D-mesons, and the inclusive jet nuclear modification factors, using Bayesian model-to-data comparison, to extract the virtuality-dependent transverse momentum broadening transport coefficient $q^$ . To facilitate this undertaking, we develop a quantitative metric for validating the Bayesian workflow, which is used to analyze the sensitivity of various model parameters to individual observables. The usefulness of this new metric in improving Bayesian model emulation is shown to be highly beneficial for future such analyses.
Comments:
24 pages, 16 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2307.09641 [pdf]
PRC(2024)·17 citations
11
[Submitted on 19 Jul 2023] (cross-list from hep-ph)
Spatial imaging of proton via leading-twist non-skewed GPDs with basis light-front quantization
Satvir Kaur🇨🇳 · Siqi Xu🇨🇳 · Chandan Mondal🇨🇳 · Xingbo Zhao🇨🇳 · James P. Vary🇺🇸
The internal image of the proton is unveiled by examining the generalized parton distributions (GPDs) at zero skewness, within the basis light-front quantized environment. Several distributions emerge when a quark is sampled with different currents depending upon the helicity arrangements of the active quark and the proton target. We investigate six of the eight leading-twist proton GPDs of the valence quarks, the helicity conserving distributions $(H, E, H ~)$ and the helicity non-conserving $(H_{T}, E_{T}, H ~_{T})$ distributions at skewness set to zero ( $ζ = 0$ ). We consider purely transverse momentum transfer and, hence, obtain results describe only the proton's two-dimensional structure in the transverse plane. We present the Mellin moments of these distribution functions, where the first moment produces a form factor and the second Mellin moments help extract the information on partonic contributions to the hadronic angular momentum. We compare our results for the Mellin moments with those from lattice QCD and other approaches where available. We also present the GPDs in transverse position space.
Comments:
29 pages, 11 figures, 3 tables, addition of Fig. 9, minor modifications in text
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2307.09869 [pdf]
PRD(2024)·37 citations
12
[Submitted on 19 Jul 2023] (cross-list from hep-ph)
Inverse problem in femtoscopic correlation functions: The $T_{cc} (3875)^{+}$ state
M. Albaladejo🇪🇸 · A. Feijoo🇪🇸 · I. Vidaña🇮🇹 · J. Nieves🇪🇸 · E. Oset🇪🇸
We study here the inverse problem of starting from the femtoscopic correlation functions of related channels and analyze them with an efficient tool to extract the maximum information possible on the interaction of the components of these channels, and the existence of possible bound states tied to this interaction. The method is flexible enough to accommodate non-molecular components and the effect of missing channels relevant for the interaction. We apply the method to realistic correlation functions for the $D^{*+} D^{0}$ and $D^{* 0} D^{+}$ channels derived consistently from the properties of the $T_{cc} (3875)^{+}$ and find that we can extract the existence of a bound state, its nature as a molecular state of the $D^{*+} D^{0}$ and $D^{* 0} D^{+}$ channels, the probabilities of each channel, as well as scattering lengths and effective ranges for the channels, together with the size of the source function, all of them with a relatively good precision.
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2307.09873 [pdf]
EPJA(2025)·31 citations
13
[Submitted on 19 Jul 2023] (cross-list from hep-ph)
Gauge invariant spectral analysis of quark hadronization dynamics
Alberto Accardi🇺🇸 · Caroline S. R. Costa🇺🇸 · Andrea Signori🇮🇹
We study the Dirac decomposition of the gauge invariant quark propagator, whose imaginary part describes the hadronization of a quark as this interacts with the vacuum, and relate each of its coefficients to a specific sum rule for the chiral-odd and chiral-even quark spectral functions. Working at first in light-like axial gauge, we obtain a new sum rule for the spectral function associated to the gauge fixing vector, and show that its second moment is in fact equal to zero. Then, we demonstrate that the first moment of the chiral-odd quark spectral function is equal in any gauge to the so-called inclusive jet mass, which is related to the mass of the particles produced in the hadronization of a quark. Finally, we present a gauge-dependent formula that connects the second moment of the chiral-even quark spectral function to invariant mass generation and final state rescattering in the hadronization of a quark.
Comments:
16 pages
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2307.10152 [pdf]
PRD(2023)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE