Nuclear Theory·nucl-th

Tuesday·November 30, 2021

27 papers—14 primary·13 cross-listed

01
Pairing effects in nuclear pasta phase within the relativistic Thomas-Fermi formalism
U. J. Furtado · S. S. Avancini · J. R. Marinelli
Pairing effects in non-uniform nuclear matter, surrounded by electrons, are studied in the protoneutron star early stage and in other conditions. The so-called nuclear pasta phases at subsaturation densities are solved in a Wigner-Seitz cell, within the Thomas-Fermi approximation. The solution of this problem is important for the understanding of the physics of a newly born neutron star after a supernova explosion. It is shown that the pasta phase is more stable than uniform nuclear matter on some conditions and the pairing force relevance is studied in the determination of these stable phases.
nucl-thJ.Phys.G(2022)·7 citations
02
Hidden charm mesons in nuclear matter and nuclei
J.J. Cobos-Martínez🇲🇽 · K. Tsushima🇧🇷 · G. Krein🇧🇷 · A.W. Thomas🇦🇺
Recent results for the $η_{c}$ - and $J / ψ$ -nucleus bound state energies for various nuclei are presented. The attractive potentials for the $η_{c}$ and $J / ψ$ mesons in the nuclear medium originate, respectively, from the in-medium enhanced $D D^{*}$ and $D D ˉ$ loops in the $η_{c}$ and $J / ψ$ self energies. Our results suggest that the $η_{c}$ and $J / ψ$ mesons should form bound states with all the nuclei considered.
nucl-thhep-exhep-phnucl-exPoS(2022)·2 citations
03
Semi-analytical calculation of the trajectory of relativistic nuclear collisions in the QCD phase diagram
Todd Mendenhall🇺🇸 · Zi-Wei Lin🇺🇸
We extend a semi-analytical model that includes the finite nuclear thickness to calculate the energy density $ϵ (t)$ and conserved-charge densities including the net-baryon density $n_{_{B}} (t)$ produced at mid-spacetime-rapidity in central Au+Au collisions. Assuming the formation of a quark-gluon plasma with an ideal gas equation of state of either quantum or Boltzmann statistics or with a lattice QCD-based equation of state, we extract the temperature $T$ and chemical potentials $μ_{_{B}}$ , $μ_{_{Q}}$ and $μ_{_{S}}$ as functions of time. This then allows us to semi-analytically calculate the $T - μ_{_{B}}$ trajectory of relativistic nuclear collisions in the QCD phase diagram, which should benefit the studies of high density physics including the search for the critical end point. This model is also useful for exploring the trajectories in the more general $T - μ_{_{B}} - μ_{_{Q}} - μ_{_{S}}$ QCD phase space.
nucl-thnucl-exPRC(2023)·6 citations
04
Coupled baryon, electric charge and strangeness fluctuations in heavy-ion collisions
Grégoire Pihan🇫🇷 · Marcus Bluhm🇫🇷 · Marlene Nahrgang🇫🇷
We present for the first time quantitative results for the coupled dynamics of second order fluctuations in the three conserved charges of QCD based on stochastic diffusion equations for a Bjorken-type expanding hadronic medium.
nucl-thhep-phEPJ Web Conf.(2022)·1 citation
05
Momentum dependence of near-threshold photoproduction of $Ξ^{-}$ hyperons off nuclei and their properties in the nuclear medium
E. Ya. Paryev🇷🇺
We study the near-threshold inclusive photoproduction of $Ξ^{-}$ hyperons off $^{12}$ C and $^{184}$ W target nuclei within a first-collision model relying on the nuclear spectral function and including incoherent $Ξ^{-}$ production in direct elementary $γ p \to K^{+} K^{+} Ξ^{-}$ and $γ n \to K^{+} K^{0} Ξ^{-}$ processes. The model takes into account the impact of the nuclear effective scalar $K^{+}$ , $K^{0}$ , $Ξ^{-}$ and their Coulomb potentials on these processes as well as the absorption of final $Ξ^{-}$ hyperons in nuclear matter, the binding of intranuclear nucleons and their Fermi motion. We calculate the absolute differential cross sections and their ratios for the production of $Ξ^{-}$ hyperons off these nuclei at laboratory polar angles $\leq$ 45 $^{\circ}$ by photons with energies of 2.5 and 3.0 GeV, with and without imposing the phase space constraints on the $Ξ^{-}$ emission angle in the respective $γ p$ center-of-mass system. We also calculate the momentum dependence of the transparency ratio for $Ξ^{-}$ hyperons for the $^{184}$ W/ $^{12}$ C combination at these photon energies. We show that the $Ξ^{-}$ momentum distributions (absolute and relative) at the adopted initial photon energies possess, contrary to the transparency ratio for $Ξ^{-}$ hyperons, a definite sensitivity to the considered changes in the scalar $Ξ^{-}$ nuclear mean-field potential at saturation density $ρ_{0}$ in the low-momentum range of 0.1--0.8 GeV/c. Therefore, the precise measurements of these distributions in a dedicated experiment at the CEBAF facility will provide valuable information on the $Ξ^{-}$ in-medium properties, which will be supplementary to that inferred from studying of the ( $K^{-}$ , $K^{+}$ ) reactions at initial momenta of 1.6--1.8 GeV/c.
nucl-thhep-phnucl-exNPA(2022)·2 citations
06
Bayesian Data Fusion of Imperfect Fission Yields for Augmented Evaluations
Z.A. Wang · J.C. Pei · Y.J. Chen · C.Y. Qiao · F.R. Xu · Z.G. Ge · N.C. Shu
We demonstrate that Bayesian machine learning can be used to treat the vast amount of experimental fission data which are noisy, incomplete, discrepant, and correlated. As an example, the two-dimensional cumulative fission yields (CFY) of neutron-induced fission of $^{238}$ U are evaluated with energy dependencies and uncertainty qualifications. For independent fission yields (IFY) with very few experimental data, the heterogeneous data fusion of CFY and IFY is employed to interpolate the energy dependence. This work shows that Bayesian data fusion can facilitate the further utilization of imperfect raw nuclear data.
nucl-thPRC(2022)·16 citations
07
Appearance of peak in symmetry energy at N = 126 for Pb isotopic chain within relativistic energy density functional
Jeet Amrit Pattnaik · T. M. Joshua · Ankit Kumar · M. Bhuyan · S. K. Patra
The newly derived relativistic energy density functional [\textcolor{blue}{ Phys. Rev. C \textbf{103}, 024305 (2021)}], which stems from the effective field theory motivated relativistic mean-field (E-RMF) is employed to establish the appearance of peak/kink in the symmetry energy over the isotopic chain of Pb-nuclei. The coherent density fluctuation model parametrization procedure for finite nuclei is adopted here to obtain the relativistic energy density functional at local density. The relativistic energy density functional from E-RMFT takes precedence over the Brückner energy density functional as it accurately predicts the empirical saturation density and binding energy per nucleon $E / A$ , so-called 'Coester Band Problem'. Interestingly, using the relativistic energy density functional, it is possible to predict the peak at $N = 126$ for recently developed G3 and widely used NL3 parameter sets, which is not observed for Brückener's functional in-spite of using the E-RMF density. From the present analysis, the newly fitted energy density functional is found to be minutely sensitive to the choice of the parameter sets employed.
nucl-thPRC(2022)·14 citations
08
Systematic study of two-proton radioactivity half-lives based on a modified Gamow-like model
Hong-Ming Liu · You-Tian Zou · Xiao Pan · Biao He · Xiao-Hua Li
In the present work, we systematically study the two-proton (2p) radioactivity half-lives of nuclei close to the proton drip line within a modified Gamow-like model. Using this model, the calculated 2p radioactivity half-lives can well reproduce the experimental data. Moreover, we use this model to predict the 2p radioactivity half-lives of 22 candidates whose 2p radioactivity is energetically allowed or observed but not yet quantied in evaluated nuclear properties table NUBASE2016. The predicted results are in good agreement with the ones obtained by using Gamow-like model, effective liquid drop model (ELDM), generalized liquid drop model (GLDM) as well as a four-parameter formula.
nucl-thIJMPE(2021)·14 citations
09
A Pfaffian formulation for matrix elements of three-body operators in multiple quasi-particle configurations
Zi-Rui Chen · Long-Jun Wang
We present a Pfaffian formula to calculate matrix elements of three-body operators in symmetry-restoration beyond-mean-field methods, including the case of multiple quasi-particle configurations. Detailed derivation based on [Mizusaki et al., Phys. Lett. B 715, 219 (2012)] and [Hu et al., Phys. Lett. B 734, 162 (2014)] is provided, and potential applications in generator coordinate method with chiral interactions, as well as in study of nuclear matrix elements in neutrinoless double beta decay are discussed.
nucl-thPRC(2022)·11 citations
10
Perturbative quantum Monte Carlo method for nuclear physics
Bing-Nan Lu🇨🇳 · Ning Li🇨🇳 · Serdar Elhatisari🇹🇷 · Yuan-Zhuo Ma🇨🇳 · Dean Lee🇺🇸 · Ulf-G. Meißner🇩🇪
While first order perturbation theory is routinely used in quantum Monte Carlo (QMC) calculations, higher-order terms present significant numerical challenges. We present a new approach for computing perturbative corrections in projection QMC calculations. We demonstrate the method by computing nuclear ground state energies up to second order for a realistic chiral interaction. We calculate the binding energies of several light nuclei up to $^{16}$ O by expanding the Hamiltonian around the Wigner SU(4) limit and find good agreement with data. In contrast to the natural ordering of the perturbative series, we find remarkably large second order energy corrections. This occurs because the perturbing interactions break the symmetries of the unperturbed Hamiltonian. Our method is free from the sign problem and can be applied to QMC calculations for many-body systems in nuclear physics, condensed matter physics, ultracold atoms, and quantum chemistry.
nucl-thcond-mat.str-elhep-latPRL(2022)·48 citations
11
Description of $^{93}$ Nb stellar electron-capture rates by the Projected Shell Model
Long-Jun Wang · Liang Tan · Zhipan Li · Bingshui Gao · Yang Sun
Capture of electrons by nuclei is an important process in stellar environments where excited nuclear states are thermally populated. However, accurate treatment for excited configurations in electron capture (EC) rates has been an unsolved problem for medium-heavy and heavy nuclei. In this work, we take the $^{93}$ Nb $\to$ $^{93}$ Zr EC rates as the example to introduce the Projected-Shell-Model (PSM) in which excited configurations are explicitly included as multi-quasiparticle states. Applying the prevalent assumption that the parent nucleus always stays in its ground state in stellar conditions, we critically compare the obtained PSM results with the recently-measured Gamow-Teller transition data, and with the previous calculations by the conventional shell model and the quasiparticle random-phase approximation. We discuss important ingredients that are required in theoretical models used for stellar EC calculations, and demonstrate effects of the explicit inclusion of excited nuclear states in EC rate calculations, especially when both electron density and environment temperature are high.
nucl-thPRC(2021)·10 citations
12
Competition between diffusion and rapid expansion and its impact on critical fluctuations in heavy-ion collisions
Grégoire Pihan · Marcus Bluhm · Masakiyo Kitazawa · Marlene Nahrgang
We study the impact of the competition between the expansion of the medium created in heavy-ion collisions and its diffusive properties on the critical fluctuations of the net-baryon density. As the relaxation time of the fluctuations is connected with the diffusive properties, the latter determine the in- or out-of-equilibrium nature of the net-baryon density fluctuations during the fireball evolution. This may result in important consequences for the phenomenological interpretation of heavy-ion collision data. We study three possible situations that can occur as a result of the competition between diffusion and expansion and discuss the impact of this competition on the integrated second and fourth order cumulants of net-baryon density fluctuations at freeze-out in these situations.
nucl-thhep-phPoS(2022)·0 citations
13
Off-equilibrium non-Gaussian fluctuations near the QCD critical point: an effective field theory perspective
Noriyuki Sogabe🇨🇳 · Yi Yin🇨🇳
The non-Gaussian fluctuations of baryon density are sensitive to the presence of the conjectured QCD critical point. Their observational consequences are crucial for the ongoing experimental search for this critical point through the beam energy scan program at Relativistic Heavy Ion Collider (RHIC). In the expanding fireball created in a heavy-ion collision, critical fluctuations would inescapably fall out of equilibrium, and require a systematic description within a dynamical framework. In this paper, we employ newly developed effective field theory (EFT) for fluctuating hydrodynamics to study the real-time critical non-Gaussian fluctuations of a conserved charge density. In particular, we derive the evolution equations for multi-point correlators of density fluctuations and obtain the closed-form solutions with arbitrary initial conditions that can readily be implemented in realistic simulations for heavy-ion collisions. We find that non-linear interactions among noise fields, which are missing in traditional stochastic hydrodynamics, could potentially contribute to the quartic (fourth order) fluctuations in scaling regime even at tree level in off-equilibrium situations.
nucl-thhep-thJHEP(2022)·17 citations
14
Probing nuclear structure with mean transverse momentum in relativistic isobar collisions
Hao-jie Xu🇨🇳 · Wenbin Zhao🇺🇸 · Hanlin Li🇨🇳 · Ying Zhou🇨🇳 · Lie-Wen Chen🇨🇳 · Fuqiang Wang🇨🇳
Transverse momentum ( $p_{T}$ ) generation in relativistic heavy ion collisions is sensitive to the initial geometry and the final-state bulk evolution. We demonstrate with hydrodynamic calculations that the mean $p_{T}$ ratio ( $R_{⟨ p_{T} ⟩}$ ) between the highly similar isobar $_{44}^{96}$ Ru+ $_{44}^{96}$ Ru and $_{40}^{96}$ Zr+ $_{40}^{96}$ Zr collisions is insensitive to the bulk evolution and remains sensitive to the small difference in the initial nuclear structure (neutron skin and deformation) between the Ru and Zr nuclei.We further find that nuclear deformation can produce an anticorrelation between $R_{⟨ p_{T} ⟩}$ and eccentricity (or elliptic flow) in central collisions. These findings suggest that the $R_{⟨ p_{T} ⟩}$ between the isobar systems can be used to measure the neutron skin thickness and deformation parameters, which can in turn constrain the nuclear symmetry energy slope parameter.
nucl-thnucl-exPRC(2023)·80 citations
15
Neutrino flavor mixing with moments
McKenzie Myers🇺🇸 · Theo Cooper🇺🇸 · MacKenzie Warren🇷🇺 · Jim Kneller🇺🇸 · Gail McLaughlin🇺🇸 · Sherwood Richers🇺🇸 · Evan Grohs🇺🇸 · Carla Frohlich🇺🇸
The successful transition from core-collapse supernova simulations using classical neutrino transport to simulations using quantum neutrino transport will require the development of methods for calculating neutrino flavor transformations that mitigate the computational expense. One potential approach is the use of angular moments of the neutrino field, which has the added appeal that there already exist simulation codes which make use of moments for classical neutrino transport. Evolution equations for quantum moments based on the quantum kinetic equations can be straightforwardly generalized from the evolution of classical moments based on the Boltzmann equation. We present an efficient implementation of neutrino transformation using quantum angular moments in the free streaming, spherically symmetric bulb model. We compare the results against analytic solutions and the results from more exact multi-angle neutrino flavor evolution calculations. We find that our moment-based methods employing scalar closures predict, with good accuracy, the onset of collective flavor transformations seen in the multi-angle results. However in some situations they overestimate the coherence of neutrinos traveling along different trajectories. More sophisticated quantum closures may improve the agreement between the inexpensive moment-based methods and the multi-angle approach.
↳ hep-phastro-ph.HEastro-ph.SRnucl-thPRD(2022)·20 citations
16
Splitting rates in QCD plasmas from a non-perturbative determination of the momentum broadening kernel $C (q_{⊥})$
Soeren Schlichting🇩🇪 · Ismail Soudi🇩🇪
We exploit a recent non-perturbative determination of the momentum broadening kernel $C (b_{⊥})$ in impact parameter space \cite{Moore:2021jwe}, to determine the momentum space broadening kernel $C (q_{⊥})$ in high-temperature QCD plasmas. We show how to use the non-pertubatively determined kernel $C (q_{⊥})$ to compute the medium-induced splitting rates in a QCD plasma of finite size. We compare the resulting in-medium splitting rates to the results obtained with leading-order and next-to-leading order perturbative determinations of $C (q_{⊥})$ , as well as with various approximations of the splitting employed in the literature. Generally, we find that the differences in the splitting rates due to the momentum broadening kernel are larger than the errors associated with approximations of the splitting rate.
↳ hep-phnucl-thPRD(2022)·36 citations
17
Hypermassive quark cores
Luiz L. Lopes🇧🇷 · Carline Biesdorf🇧🇷 · Débora P. Menezes🇧🇷
Using a quantum hadrodynamics (QHD) and MIT based models we construct hybrid stars within the Maxwell criteria of hadron-quark phase transition. We are able to produce a hybrid star with maximum mass of 2.15 $M_{⊙}$ . Furthermore, a 2.03 $M_{⊙}$ star with a quark core corresponding to more than $80%$ of both, its total mass and radius, is also possible.
↳ hep-phastro-ph.HEnucl-thMNRAS(2022)·29 citations
18
Space-time symmetric qubit regularization of the asymptotically free two-dimensional O(4) model
Junzhe Zhou🇺🇸 · Hersh Singh🇺🇸 · Tanmoy Bhattacharya🇺🇸 · Shailesh Chandrasekharan🇺🇸 · Rajan Gupta🇺🇸
We explore if space-time symmetric lattice field theory models with a finite Hilbert space per lattice site can reproduce asymptotic freedom in the two-dimensional $O (4)$ model. We focus on a simple class of such models with a five dimensional local Hilbert space. We demonstrate how even the simplest model reproduces asymptotic freedom within the D-theory formalism but at the cost of increasing the size of the Hilbert space through coupling several layers of a two-dimensional lattice. We then argue that qubit regularization can be viewed as an effective field theory (EFT) even if the continuum limit cannot be reached, as long as we can tune the model close enough to the continuum limit where perturbation theory, or other analytical techniques, become viable. We construct a simple lattice model on a single layer with a four dimensional local Hilbert space that acts like an excellent EFT of the original theory.
↳ hep-latcond-mat.str-elhep-thnucl-th+1PRD(2022)·14 citations
19
Far from equilibrium Chiral Magnetic Effect in Strong Magnetic Fields from Holography
Sebastian Grieninger🇪🇸 · Sergio Morales-Tejera🇪🇸
We study the real time evolution of the chiral magnetic effect out-of-equilibrium in strongly coupled anomalous field theories. We match the parameters of our model to QCD parameters and draw lessons of possible relevance for the realization of the chiral magnetic effect in heavy ion collisions. In particular, we find an equilibration time of about $\sim 0.35$ fm/c in presence of the chiral anomaly for plasma temperatures of order $T \sim 300 - 400$ MeV.
↳ hep-phhep-thnucl-exnucl-thEPJ Web Conf.(2022)·3 citations
20
Two-photon transitions of charmonia on the light front
Yang Li🇨🇳 · Meijian Li🇫🇮 · James P. Vary🇺🇸
We investigate the two-photon transitions $H_{c c ˉ} \to γ^{*} γ$ of the charmonium system in light-front dynamics. The light-front wave functions were obtained from solving the effective Hamiltonian based on light-front holography and one-gluon exchange interaction within the basis light-front quantization approach. We compute the two-photon transition form factors as well as the two-photon decay widths for S- and P-wave charmonia, $η_{c}$ and $χ_{c J}$ and their excitations. Without introducing any free parameters, our predictions are in good agreement with the recent experimental measurements by BaBar and Belle, shedding light on the relativistic nature of charmonium.
↳ hep-phnucl-thPRD(2022)·27 citations
21
Precise measurement of differential cross sections of the {\Sigma}-p --> {\Lambda} n reaction in momentum range 470-650 MeV/c
J-PARC E40 Collaboration: K. Miwa🇯🇵 · J. K. Ahn🇰🇷 · Y. Akazawa🇯🇵 · T. Aramaki🇯🇵 · S. Ashikaga🇯🇵 · S. Callier🇫🇷 · N. Chiga🇯🇵 · S. W. Choi🇯🇵 · H. Ekawa🇯🇵 · P. Evtoukhovitch🇷🇺 · N. Fujioka🇯🇵 · M. Fujita🇯🇵 and 59 other authors
The differential cross sections of the {\Sigma}-p --> {\Lambda} n reaction were measured accurately for the {\Sigma}- momentum (p_{{\Sigma}}) ranging from 470 to 650 MeV/c at the J-PARC Hadron Experimental Facility. Precise angular information about the {\Sigma}-p --> {\Lambda} n reaction was obtained for the first time by detecting approximately 100 reaction events at each angular step of {\Delta}cos{\theta} = 0.1. The obtained differential cross sections show slightly forward-peaking structure in the measured momentum regions.The cross sections integrated for -0.7 < cos{\theta} < 1.0 were obtained as 22.5 +- 0.68 (stat.) +- 0.65 (syst.) mb and 15.8 +-0.83(stat.) +- 0.52 (syst.) mb for 470<p_{{\Sigma}}(MeV/c)<550 and 550<p_{{\Sigma}}(MeV/c)<650, respectively. These results show a drastic improvement compared to past measurements of the hyperon-proton scattering experiments. They will play essential roles in updating the theoretical models of the baryon-baryon interactions.
↳ nucl-exnucl-thPRL(2022)·53 citations
22
Narrow resonances in the continuum of the unbound nucleus $^{15}$ F
V. Girard-Alcindor (1 and 2) · A. Mercenne (3) · I. Stefan (2) · F. de Oliveira Santos (1) · N. Michel (4) · M. Płoszajczak (1) · M. Assié (2) · A. Lemasson (1) · E. Clément (1) · F. Flavigny (5) · A. Matta (5) · D. Ramos (1) and 91 other authors
The structure of the unbound $^{15}$ F nucleus is investigated using the inverse kinematics resonant scattering of a radioactive $^{14}$ O beam impinging on a CH $_{2}$ target. The analysis of $^{1}$ H( $^{14}$ O,p) $^{14}$ O and $^{1}$ H( $^{14}$ O,2p) $^{13}$ N reactions allowed the confirmation of the previously observed narrow $1/ 2^{-}$ resonance, near the two-proton decay threshold, and the identification of two new narrow 5/2 $^{-}$ and 3/2 $^{-}$ resonances. The newly observed levels decay by 1p emission to the ground of $^{14}$ O, and by sequential 2p emission to the ground state (g.s.) of $^{13}$ N via the $1^{-}$ resonance of $^{14}$ O. Gamow shell model (GSM) analysis of the experimental data suggests that the wave functions of the 5/2 $^{-}$ and 3/2 $^{-}$ resonances may be collectivized by the continuum coupling to nearby 2p- and 1p- decay channels. The observed excitation function $^{1}$ H( $^{14}$ O,p) $^{14}$ O and resonance spectrum in $^{15}$ F are well reproduced in the unified framework of the GSM.
↳ nucl-exnucl-thPRC(2022)·19 citations
23
On the $QQ q ˉ q ˉ$ -Quark Potential in String Models
Oleg Andreev🇷🇺
We propose a string theory construction for the system of two heavy quarks and two light antiquarks. The potential of the system is a function of separation between the quarks. We define a critical separation distance below which the system can be thought of mainly as a compact tetraquark. The results show the universality of the string tension and factorization at small separations expected from heavy quark-diquark symmetry. Our estimate of the screening length is in the range of lattice QCD. We also make a comparison with the potential of the $QQq$ system. The potentials look very similar at small quark separations but at larger separations they differ. The reason for this is that the flattening of the potentials happens at two well-separated scales as follows from the two different mechanisms: string breaking by light quarks for $QQq$ and string junction annihilation for $QQ q ˉ q ˉ$ . Moreover, a similar construction can also be applied to the $Q ˉ Q ˉ q q$ system.
↳ hep-phhep-lathep-thnucl-thPRD(2022)·27 citations
24
Efimovian states of three charged particles
Yusuke Nishida
When three particles in three dimensions interact with a short-range potential fine-tuned to an infinite scattering length, they form an infinite sequence of loosely bound states obeying discrete scale invariance known as Efimov states. Here we show that analogous states are formed by three charged particles carrying two equal charges and one opposite charge in one, two, and three dimensions without any fine-tuning. Our finding is based on the Born-Oppenheimer approximation, where an effective inverse-square attraction is induced as a consequence of the dipole-charge interaction between a hydrogenlike heavy-light atom and a far-separated heavy particle. Because the resulting Efimovian states emerge toward the second or higher dissociation threshold, they are to be realized as quasibound states and may be observed by exciting hydrogen molecular ions and trions in excitonic systems. We also consider the same system but with a logarithmic Coulomb potential relevant to quantum vortices in two-dimensional superfluids, where the Efimovian states are shown to emerge as genuine bound states toward the first dissociation threshold.
↳ physics.atom-phcond-mat.mes-hallnucl-thphysics.chem-phPRA(2022)·2 citations
25
Progress in the determination of Mellin moments of the pion LCDA using the HOPE method
William Detmold🇺🇸 · Anthony V. Grebe🇺🇸 · Issaku Kanamori🇯🇵 · C.-J. David Lin🇹🇼 · Santanu Mondal🇺🇸 · Robert J. Perry🇹🇼 · Yong Zhao🇺🇸
The pion light-cone distribution amplitude (LCDA) is a central non-perturbative object of interest for the calculation of high-energy exclusive processes in quantum chromodynamics. In this article, we discuss the calculation of the second and fourth Mellin moment of the pion LCDA using a heavy-quark operator product expansion. The resulting value for the second Mellin moment is $⟨ ξ^{2} ⟩ (μ = 2 GeV) = 0.210 \pm 0.013 (stat.) \pm 0.034 (sys.)$ . This result is compatible with those from previous determinations of this quantity.
↳ hep-lathep-phnucl-thPoS(2022)·4 citations
26
The information content of jet quenching and machine learning assisted observable design
Yue Shi Lai🇺🇸 · James Mulligan🇺🇸 · Mateusz Płoskoń🇺🇸 · Felix Ringer🇺🇸
Jets produced in high-energy heavy-ion collisions are modified compared to those in proton-proton collisions due to their interaction with the deconfined, strongly-coupled quark-gluon plasma (QGP). In this work, we employ machine learning techniques to identify important features that distinguish jets produced in heavy-ion collisions from jets produced in proton-proton collisions. We formulate the problem using binary classification and focus on leveraging machine learning in ways that inform theoretical calculations of jet modification: (i) we quantify the information content in terms of Infrared Collinear (IRC)-safety and in terms of hard vs. soft emissions, (ii) we identify optimally discriminating observables that are in principle calculable in perturbative QCD, and (iii) we assess the information loss due to the heavy-ion underlying event and background subtraction algorithms. We illustrate our methodology using Monte Carlo event generators, where we find that important information about jet quenching is contained not only in hard splittings but also in soft emissions and IRC-unsafe physics inside the jet. This information appears to be significantly reduced by the presence of the underlying event. We discuss the implications of this for the prospect of using jet quenching to extract properties of the QGP. Since the training labels are exactly known, this methodology can be used directly on experimental data without reliance on modeling. We outline a proposal for how such an experimental analysis can be carried out, and how it can guide future measurements.
↳ hep-phhep-exnucl-exnucl-thJHEP(2022)·29 citations
27
Dynamically groomed jet radius in heavy-ion collisions
Paul Caucal🇺🇸 · Alba Soto-Ontoso🇫🇷 · Adam Takacs🇳🇴
We explore the ability of a recently proposed jet substructure technique, Dynamical Grooming, to pin down the properties of the Quark-Gluon Plasma formed in ultra-relativistic heavy-ion collisions. In particular, we compute, both analytically and via Monte-Carlo simulations, the opening angle $θ_{g}$ of the hardest splitting in the jet as defined by Dynamical Grooming. Our calculation, grounded in perturbative QCD, accounts for the factorization in time between vacuum-like and medium-induced processes in the double logarithmic approximation. We observe that the dominating scale in the $θ_{g}$ -distribution is the decoherence angle $θ_{c}$ which characterises the resolution power of the medium to propagating color probes. This feature also persists in strong coupling models for jet quenching. We further propose for potential experimental measurements a suitable combination of the Dynamical Grooming condition and the jet radius that leads to a pQCD dominated observable with a very small sensitivity ( $\leq 10%$ ) to medium response.
↳ hep-phnucl-thPRD(2022)·61 citations

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first authorsco-authorsvia INSPIRE