Thu·Jul 11, 2024Thursday·July 11, 2024

1. 01*

   The Proton Electromagnetic Generalized Polarizabilities

   Nikos Sparveris🇺🇸

   The electromagnetic polarizabilities are fundamental properties of the proton that characterize its response to an external EM field. The generalization of the EM polarizabilities to non-zero four-momentum transfer opens up a powerful path to study the internal structure of the proton. They map out the spatial distribution of the polarization densities in the proton, provide access to key dynamical mechanisms that contribute to the electric and the magnetic polarizability effects, and allow to determine fundamental characteristics of the system, such as the electric and the magnetic polarizability radii. This article reviews the knowledge of the proton EM generalized polarizabilities. An introduction is given to the basic concepts and to the theoretical framework, that is then followed by a discussion that emphasizes the recent developments and findings of the Virtual Compton scattering experiments and future perspectives on the topic.

   nucl-exnucl-thFront.Phys.(2024)·2 citations
2. 02*

   Flattenicity as "centrality" estimator in p-Pb collisions simulated with PYTHIA 8.312 Angantyr

   Antonio Ortiz🇲🇽 · Gyula Bencedi🇭🇺 · Feng Fan🇨🇳

   In this paper, a "centrality" estimator based on flattenicity ($\rho$) is studied in proton-led (p-Pb) collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV using PYTHIA 8 Angantyr. Although Angantyr is still under development, the existing implementation is enough to study the particle production in systems where medium effects are absent. Firstly, ALICE data on pseudorapidity distributions as a function of the forward multiplicity (V0M), as well as transverse momentum distributions of identified particles in non-single diffractive p-Pb collisions, are compared with Angantyr. Secondly, the average number of binary nucleon-nucleon ($N_{\mathrm{coll}}$) collisions for different "centrality" estimators are compared. The studies include the following "centrality" estimators: V0M, $\rho$ and midrapidity multiplicity (CL1). On one hand, the "centrality" dependence of $⟨N_{\mathrm{coll}}⟩$ for the $\rho$ selection shows the smallest deviations ($<8$ %) with respect to that obtained using impact parameter $b$; on the other hand, the V0M and CL1 yield huge deviations (up to a factor 2) with respect to the results using $b$. The particle ratios and nuclear modification factors ($Q_{\mathrm{pPb}}$) as a function of $p_{\mathrm{T}}$ are also studied. The proton-to-pion ratio exhibits a flow-like peak at intermediate $p_{\mathrm{T}}$ (2-8 GeV/$c$) with little or no "centrality" dependence for V0M, $\rho$ and $b$ selections. The kaon-to-pion ratio as a function of $p_{\mathrm{T}}$ is "centrality" independent for the same selections. On the contrary, for the CL1 class the ratios exhibit the typical behaviour associated with hard physics. Regarding $Q_{\mathrm{pPb}}$, a peak at intermediate $p_{\mathrm{T}}$ ($2-8$ GeV/$c$) for different particle species is observed when the "centrality" is obtained with $b$ or $\rho$. The observed features diminish for the selections based on V0M and CL1.

   nucl-exhep-phJ.Phys.G(2024)·5 citations
3. 03*

   Deep(er) Reconstruction of Imaging Cherenkov Detectors with Swin Transformers and Normalizing Flow Models

   Cristiano Fanelli🇺🇸 · James Giroux🇺🇸 · Justin Stevens🇺🇸

   Imaging Cherenkov detectors are crucial for particle identification (PID) in nuclear and particle physics experiments. Fast reconstruction algorithms are essential for near real-time alignment, calibration, data quality control, and efficient analysis. At the future Electron-Ion Collider (EIC), the ePIC detector will feature a dual Ring Imaging Cherenkov (dual-RICH) detector in the hadron direction, a Detector of Internally Reflected Cherenkov (DIRC) in the barrel, and a proximity focus RICH in the electron direction. This paper focuses on the DIRC detector, which presents complex hit patterns and is also used for PID of pions and kaons in the GlueX experiment at JLab. We present Deep(er)RICH, an extension of the seminal DeepRICH work, offering improved and faster PID compared to traditional methods and, for the first time, fast and accurate simulation. This advancement addresses a major bottleneck in Cherenkov detector simulations involving photon tracking through complex optical elements. Our results leverage advancements in Vision Transformers, specifically hierarchical Swin Transformer and normalizing flows. These methods enable direct learning from real data and the reconstruction of complex topologies. We conclude by discussing the implications and future extensions of this work, which can offer capabilities for PID for multiple cutting-edge experiments like the future EIC.

   ↳ physics.ins-detcs.LGhep-exnucl-ex+1Mach.Learn.Sci.Tech.(2025)·6 citations
4. 04*

   A Decade of Collectivity in Small Systems

   Jan Fiete Grosse-Oetringhaus🇨🇭 · Urs Achim Wiedemann🇨🇭

   Signatures of collectivity, including azimuthally anisotropic and radial flow as well as characteristic hadrochemical dependencies, have been observed since long in (ultra)relativistic nucleus-nucleus collisions. They underpin the interpretation of these collision systems in terms of QGP formation and close-to-perfect fluidity. Remarkably, however, essentially all these signatures of collectivity have been identified within the last decade in collision systems as small as pp and p-Pb, where collective phenomena had been assumed to be absent traditionally. Precursor phenomena may have been found even in ep and $e^{+}{e}^{-}$ collisions. This article provides a complete review of all data on small system collectivity. It reviews model simulations of these data where available. However, in the absence of a phenomenologically fully satisfactory description of collectivity across all system sizes, we focus in particular on the theoretical basis of all dynamical frameworks of collectivity invoked in heavy ion collisions, and their expected scaling with system size. Our discussion clarifies to what extent all dynamical explanations are challenged by the available data.

   ↳ hep-exhep-phnucl-ex85 citations
5. 05*

   Bayesian Inference of Fine-Features of Nuclear Equation of State from Future Neutron Star Radius Measurements to 0.1km Accuracy

   Bao-An Li🇺🇸 · Xavier Grundler🇺🇸 · Wen-Jie Xie🇨🇳 · Nai-Bo Zhang🇨🇳

   To more precisely constrain the Equation of State (EOS) of supradense neutron-rich nuclear matter, future high-precision X-ray and gravitational wave observatories are proposed to measure the radii of neutron stars (NSs) with an accuracy better than about 0.1 km. However, it remains unclear what particular aspects (other than the stiffness generally spoken of in the literature) of the EOS and to what precision they will be better constrained. In this work, within a Bayesian framework using a meta-model EOS for NSs, we infer the posterior probability distribution functions (PDFs) of incompressibility $K_0$ and skewness $J_0$ of symmetric nuclear matter (SNM) as well as the slope $L$, curvature $K_{\mathrm{sym}}$, and skewness $J_{\mathrm{sym}}$ characterizing the density dependence of nuclear symmetry energy $E_{\mathrm{sym}}(\rho )$, respectively, from mean values of NS radii consistent with existing observations and an expected accuracy $\Delta R$ ranging from about 1.0 km to 0.1 km. We found that (1) the $\Delta R$ has little effect on inferring the stiffness of SNM at suprasaturation densities, (2) smaller $\Delta R$ reveals more accurately not only the PDFs but also pairwise correlations among parameters characterizing high-density $E_{\mathrm{sym}}(\rho )$, (3) a double-peak feature of the PDF($K_{\mathrm{sym}}$) corresponding to the strong $K_{\mathrm{sym}}-J_{\mathrm{sym}}$ and $K_{\mathrm{sym}}-L$ anti-correlations is revealed when $\Delta R$ is less than about 0.2 km, and the locations of the two peaks are sensitive to the maximum value of $J_{\mathrm{sym}}$ reflecting the stiffness of $E_{\mathrm{sym}}(\rho )$ above about 3 times the saturation density ${\rho }_0$ of SNM, (4) the high-precision radius measurement for canonical NSs is more useful than that for massive ones for constraining the EOS of nucleonic matter around $(2-3){\rho }_0$.

   ↳ astro-ph.HEastro-ph.GAastro-ph.SRnucl-ex+1PRD(2024)·28 citations
6. 06*

   Probe and Prejudice: Classification of compact objects and model comparison using EOS knowledge

   Hauke Koehn🇩🇪 · Thibeau Wouters🇳🇱 · Henrik Rose🇩🇪 · Peter T. H. Pang🇳🇱 · Rahul Somasundaram🇺🇸 · Ingo Tews🇺🇸 · Tim Dietrich🇩🇪

   Nuclear theory and experiments, alongside astrophysical observations, constrain the equation of state (EOS) of supranuclear-dense matter. Conversely, knowledge of the EOS allows an improved interpretation of nuclear or astrophysical data. In this article, we use several established constraints on the EOS and the new NICER measurement of PSR J0437-4715 to comment on the nature of the primary companion in GW230529 and the companion of PSR J0514-4002E. We find that, with a probability of $\gtrsim 84\%$ and $\gtrsim 68\%$, respectively, both objects are black holes. These likelihoods increase to above $95\%$ when one uses GW170817's remnant as an upper limit on the TOV mass. We also demonstrate that the current knowledge of the EOS substantially disfavors high masses and radii for PSR J0030+0451, inferred recently when combining NICER with XMM-Newton background data and using particular hot-spot models. Finally, we also use our obtained EOS knowledge to comment on measurements of the nuclear symmetry energy, finding that the large value predicted by the PREX-II measurement displays some mild tension with other constraints on the EOS.

   ↳ astro-ph.HEgr-qcnucl-exnucl-thPRD(2024)·16 citations
7. 07*

   Towards an Interpretation of the First Measurements of Energy Correlators in the Quark-Gluon Plasma

   Carlota Andres🇫🇷 · Fabio Dominguez🇪🇸 · Jack Holguin🇬🇧 · Cyrille Marquet🇫🇷 · Ian Moult🇺🇸

   Energy correlators have recently been proposed as a class of jet substructure observables that directly link experimental measurements of the asymptotic energy flux with the field theoretic description of the underlying microscopic dynamics. This link holds particular promise in heavy-ion physics, where both experimental measurements and theoretical interpretations are inherently complex. With recent measurements of energy correlators in proton-proton collisions, the first measurement of these observables on inclusive jets in heavy-ion collisions underscores the importance of a theoretical understanding of their behavior in this complex environment. In this manuscript, we extend our previous calculations to account for several effects necessary for a qualitative understanding of the behavior of energy correlators on inclusive jets in heavy-ion collisions. Through a semi-analytic approach implemented in a hydrodynamically expanding quark-gluon plasma (QGP), we account for medium-induced radiation with leading broadening effects, selection biases arising from energy loss, and a description of the confinement transition. Our results represent a crucial first step towards interpreting the measurements of energy correlators on inclusive jets in heavy-ion collisions, which marks a significant milestone in connecting heavy-ion experiment and fundamental quantum field theory, in the quest to disentangle the microscopic dynamics of the QGP.

   ↳ hep-phhep-exhep-thnucl-ex+1JHEP(2025)·46 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.