Tue·Apr 30, 2024Tuesday·April 30, 2024

1. 01*

   "Rosenbluth" separation of the $J/\psi$ near-threshold photoproduction -- an access to the gluon Gravitational Form Factors at high $t$

   Lubomir Pentchev🇺🇸 · Eugene Chudakov🇺🇸

   We perform analysis of the near-threshold $J/\psi$ photoproduction data off the proton based on two theoretical approaches, GPD [1] and holographic [2], that represent the differential cross sections as powers of the skewness parameter with coefficients that depend only on the momentum transfer $t$. This allows to separate kinematically the corresponding coefficient functions, in much the same way as this is done for the electric and magnetic form factors using the Rosenbluth separation. We examine the independence of the extracted functions with the photon beam energy. These functions, under additional assumptions, are related to the proton's gluon Gravitational Form Factors (gGFFs). We compare the extracted functions with lattice calculations of the gGFFs in the region of $0.5<|t|<2$~GeV${}^2$, where they overlap. Such analysis demonstrates the possibility of extracting some combinations of the gGFFs from the data at high $t$, complementary to the lattice calculations available in the low $t$ region. However, higher statistics are needed to more accurately check the predicted scaling behavior of the data and compare with the lattice results, thus testing and comparing the theoretical assumptions used in the GPD and holographic models.

   nucl-exhep-phPRD(2025)·11 citations
2. 02*

   Contribution to differential ${\pi }^0$ and ${\gamma }_{\mathrm{dir}}$ modification in small systems from color fluctuation effects

   Dennis V. Perepelitsa🇺🇸

   A major complication in the search for jet quenching in proton- or deuteron-nucleus collision systems is the presence of physical effects which influence the experimental determination of collision centrality in the presence of a hard process. For example, in the proton color fluctuation picture, protons with a large Bjorken-$x$ ($x\gtrsim 0.1$) parton interact more weakly with the nucleons in the nucleus, leading to a smaller (larger) than expected yield in large (small) activity events. A recent measurement by PHENIX compared the yield of neutral pion and direct photon production in $d$+Au collisions, under the argument that the photon yields correct for such biases, and the difference between the two species is thus attributable to final-state effects (i.e., jet quenching). The main finding suggests a significant degree of jet quenching for hard processes in small systems. In this paper, I argue that the particular photon and pion events selected by PHENIX arise from proton configurations with significantly different Bjorken-$x$ distributions, and thus are subject to different magnitudes of modification in the color fluctuation model. Using the results of a previous global analysis of RHIC and LHC data, I show that potentially all of the pion-to-photon difference in PHENIX data can be described by a proton color fluctuation picture at a quantitative level before any additional physics from final-state effects is required. This finding reconciles the interpretation of the PHENIX measurement with others at RHIC and LHC, which have found no observable evidence for jet quenching in small systems.

   ↳ nucl-thhep-phnucl-exPRC(2024)·18 citations
3. 03*

   Exploring system size dependence of jet modification in heavy-ion collisions

   Yang He🇨🇳 · Mengxue Zhang🇨🇳 · Maowu Nie🇨🇳 · Shanshan Cao🇨🇳 · Li Yi🇨🇳

   In relativistic heavy-ion collisions, jet quenching in quark-gluon plasma (QGP) has been extensively studied, revealing important insights into the properties of the color deconfined nuclear matter. Over the past decade, there has been a surge of interest in the exploration of QGP droplets in small collision systems like $p$+$p$ or $p$+A collisions driven by the observation of collective flow phenomena. However, the absence of jet quenching, a key QGP signature, in these systems poses a puzzle. Understanding how jet quenching evolves with system size is crucial for uncovering the underlying physics. In this study, we employ the linear Boltzmann transport (LBT) model to investigate jet modification in ${}^{96}$Ru+${}^{96}$Ru, ${}^{96}$Zr+${}^{96}$Zr, and ${}^{197}$Au+${}^{197}$Au collisions at $\sqrt{s_{NN}}=200$ GeV. Our findings highlight the system size sensitivity exhibited by jet nuclear modification factor ($R_{\mathrm{AA}}$) and jet shape ($\rho$), contrasting to the relatively weak responses of jet mass ($M$), girth ($g$) and momentum dispersion ($p_{\mathrm{T}}D$) to system size variations. These results offer invaluable insights into the system size dependence of the QGP properties and await experimental validation at the Relativistic Heavy-Ion Collider.

   ↳ nucl-thhep-phnucl-exPRC(2024)·2 citations
4. 04*

   Detailed derivation of the ${}^3{\mathbf{P}}_0$ strong decay model applied to baryons

   T. Aguilar🇪🇨 · A. Capelo-Astudillo🇪🇨 · M. Conde-Correa🇪🇨 · A. Duenas-Vidal🇪🇨 · P. G. Ortega🇪🇸 · J. Segovia🇪🇸

   We provide an in-detail derivation through the ${}^3{P}_0$ pair creation model of the transition matrix for a baryon decaying into a meson-baryon system. The meson's analysis was conducted in Ref. [1] and we extend the same formalism to the baryon sector, focusing on the $\Delta (1232)\to \pi N$ strong decay width because all hadrons involved in the reaction are very well established, the two hadrons in the final state are stable, avoiding further analysis, all quarks are light and so equivalent, and the decay width of the process is relatively well measured. Taking advantage of a Gaussian expansion method for the hadron's radial wave functions, the expression of the invariant matrix element can be related with the mean-square radii of hadrons involved in the decay. We use their experimental measures in such a way that only the strength of the quark-antiquark pair creation from the vacuum is a free parameter. This is then taken from our previous study of strong decay widths in the meson sector, obtaining a quite compatible result with experiment for the calculated $\Delta (1232)\to \pi N$ decay width.

   ↳ hep-phhep-exhep-latnucl-ex+1CPC(2025)·1 citation
5. 05*

   Implication of odd-even staggering in the charge radii of calcium isotopes

   Rong An🇨🇳 · Xiang Jiang🇺🇸 · Na Tang · Li-Gang Cao · Feng-Shou Zhang🇨🇳

   Inspired by the profoundly observed odd-even staggering and the inverted parabolic-like shape in charge radii along calcium isotopic chain, the ground state properties of calcium isotopes are investigated by constraining the root-mean-square (rms) charge radii under the covariant energy density functionals with effective forces NL3 and PK1. In this work, the pairing correlations are tackled by solving the state-dependent Bardeen-Cooper-Schrieffer equations. The calculated results suggest that the binding energies obtained by the radius constraint method have been slightly changed by about $0.2\%$. But for charge radii, the corresponding results deriving from NL3 and PK1 forces have been increased by about $1.0\%$ and $2.0\%$, respectively. This means that charge radius is a more sensitive quantity in the calibrated protocol. Meanwhile, it is found that the reproduced charge radii of calcium isotopes are attributed to the rather strong isospin dependence of effective potential. The odd-even oscillation behavior can also be presented in the proton Fermi energies along calcium isotopic family, but keep opposite trends with respect to the corresponding binding energies and charge radii. As encountered in charge radii, the weakened odd-even oscillation behavior is still emerged from the proton Fermi energies at the neutron numbers $N=20$ and $28$ as well, but not in binding energies.

   ↳ nucl-thnucl-exCommun.Theor.Phys.(2025)·0 citations
6. 06*

   Femtoscopy can tell whether $Z_c(3900)$ and $Z_{cs}(3985)$ are resonances or virtual states

   Zhi-Wei Liu🇨🇳 · Jun-Xu Lu🇨🇳 · Ming-Zhu Liu🇨🇳 · Li-Sheng Geng🇨🇳

   There have been extended and heated discussions on the nature of the two exotic states, $Z_c(3900)$ and $Z_{cs}(3985)$, particularly whether they are near-threshold resonances, virtual states, or bound states. In this work, we demonstrate for the first time that the femtoscopic technique can be employed to distinguish between these three scenarios. More concretely, based on the Koonin-Pratt formula with a Gaussian source, we show that the low-momentum $D^0{D}^{\ast -}$/$D^0{D}_s^{\ast -}$ correlation functions significantly differ in the three scenarios. The high-momentum results exhibit distinct characteristics in the resonant and virtual state scenarios, especially in small collision systems of 1 fm, as produced in $pp$ collisions at the LHC. We hope that these discoveries will stimulate further experimental studies and help clarify the nature of the many exotic states that have been discovered.

   ↳ hep-phhep-exnucl-exnucl-thSci.Bull.(2025)·36 citations
7. 07*

   Disentangling the development of collective flow in high energy proton proton collisions with a multiphase transport model

   Liang Zheng🇨🇳 · Lian Liu🇨🇳 · Zi-Wei Lin🇺🇸 · Qi-Ye Shou🇨🇳 · Zhong-Bao Yin🇨🇳

   In this work, we investigate the collective flow development in high energy proton proton (pp) collisions with a multiphase transport model (AMPT) based on PYTHIA8 initial conditions with a sub-nucleon structure. It is found that the PYTHIA8 based AMPT model can reasonably describe both the charged hadron productions and elliptic flow experimental data measured in pp collisions at $\sqrt{s}=13$ TeV. By turning on the parton and hadron rescatterings in AMPT separately, we find that the observed collective flow in pp collisions is largely developed during the parton evolution, while no significant flow effect can be generated with the pure hadronic rescatterings. It is also shown that the parton escape mechanism is important for describing both the magnitude of the two-particle cumulant and the sign of the four-particle cumulants. We emphasize that the strong mass ordering of the elliptic flow results from the coalescence process in the transport model and can thus be regarded as unique evidence related to the creation of deconfined parton matter in high energy pp collisions.

   ↳ nucl-thhep-phnucl-exEPJC(2024)·11 citations
8. 08*

   Alpha radioactivity deep-underground as a probe of axion dark matter

   Carlo Broggini🇮🇹 · Giuseppe Di Carlo🇮🇹 · Luca Di Luzio🇮🇹 · Claudio Toni🇮🇹

   We propose to investigate the time modulation of radioisotope decays deep underground as a method to explore axion dark matter. In this work, we focus on the $\alpha$-decay of heavy isotopes and develop a theoretical description for the $\theta$-dependence of $\alpha$-decay half-lives, which enables us to predict the time variation of $\alpha$-radioactivity in response to an oscillating axion dark matter background. To probe this scenario, we have recently constructed and installed a setup deep underground at the Gran Sasso Laboratory, based on the $\alpha$-decay of Americium-241. This prototype experiment, named RadioAxion-$\alpha$, will allow us to explore a broad range of oscillation's periods, from a micro-second up to one year, thus providing competitive limits on the axion decay constant across 13 orders of magnitude in the axion mass, ranging from $10^{-9}$ eV to $10^{-20}$ eV after one month of data collection, and down to $10^{-22}$ eV after three years.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2024)·9 citations
9. 09*

   Evidence for polyimide redeposition and possible correlation with sparks in Gas Electron Multipliers working in CF${}_4$ mixtures

   Thiago B. Saramela · Tiago F. Silva · Marco Bregant🇧🇷 · Marcelo G. Munhoz🇧🇷 · Tien T. Quach · Richard Hague · Ian S. Gilmore · Clive J. Roberts · Gustavo F. Trindade

   Research on aging processes of Gas Electron Multipliers (GEMs) is important to obtain insights on how to increase the detector's longevity, stability, and performance, as highlighted in the latest developments roadmap by the European Council of Future Accelerators (ECFA). One key aspect of the aging process is the deposit formation on the electrodes surfaces. In this work, through the analysis of the molecular content on the surface of a used GEM, we provide evidence for polyimide redeposition as a source of organic material contributing to the formation of insulating layers on the electrodes, which eventually lead to sparks and detector failure. Furthermore, we show that chromium, used to promote adhesion between copper and polyimide, in the device undergoes a diffusion process, effectively blurring the layered structure. We demonstrate the significance of surface-sensitive chemical analysis to investigate the surface deposits on electrodes of gaseous detectors and our results reveal the necessity of standardization and more stringent study protocols.

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2024)·1 citation

* 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.