Thu·Jan 25, 2024Thursday·January 25, 2024

1. 01*

   First study of the initial gluonic fluctuations using UPCs with ALICE

   Adam Tomasz Matyja (for the ALICE Collaboration)🇵🇱

   Incoherent and dissociative J/$\psi$ photoproduction is sensitive to fluctuations of the gluonic structure of the target. Thus, the measurement of J/$\psi$ photoproduction of the colliding hadron sheds light on the initial state of QCD and provides important constraints on the initial conditions used in hydrodynamical models of heavy-ion collisions. The first measurement of the transverse momentum dependence of both coherent and incoherent J/$\psi$ photoproduction in ultraperipheral Pb-Pb collisions at midrapidity is presented. These new results provide, for the first time, a clear indication of subnucleonic fluctuations of the lead target. We also present the new measurement of dissociative J/$\psi$ photoproduction cross section as a function of energy, in p-Pb collisions at forward rapidity. Dissociative results do not show any indication of saturation and agree with previous data.

   nucl-exEPJ Web Conf.(2024)·0 citations
2. 02*

   Studying the interaction between charm and light-flavor mesons

   ALICE Collaboration

   The two-particle momentum correlation functions between charm mesons (${\mathrm{D}}^{\ast \pm }$ and ${\mathrm{D}}^{\pm }$) and charged light-flavor mesons (${\pi }^{\pm }$ and K${}^{\pm }$) in all charge-combinations are measured for the first time by the ALICE Collaboration in high-multiplicity proton-proton collisions at a center-of-mass energy of $\sqrt{s}=13$ TeV. For $\mathrm{DK}$ and ${\mathrm{D}}^{\ast }\mathrm{K}$ pairs, the experimental results are in agreement with theoretical predictions of the residual strong interaction based on quantum chromodynamics calculations on the lattice and chiral effective field theory. In the case of $\mathrm{D}\pi$ and ${\mathrm{D}}^{\ast }\pi$ pairs, tension between the calculations including strong interactions and the measurement is observed. For all particle pairs, the data can be adequately described by Coulomb interaction only, indicating a shallow interaction between charm and light-flavor mesons. Finally, the scattering lengths governing the residual strong interaction of the $\mathrm{D}\pi$ and ${\mathrm{D}}^{\ast }\pi$ systems are determined by fitting the experimental correlation functions with a model that employs a Gaussian potential. The extracted values are small and compatible with zero.

   nucl-exhep-exPRD(2024)·58 citations
3. 03*

   Collectivity inside high-multiplicity jets in high-energy proton-proton collisions

   Wenbin Zhao🇺🇸 · Zi-Wei Lin🇨🇳 · Xin-Nian Wang

   We present the first study of collectivity inside jets with high charged multiplicity $N_{\mathrm{ch}}^j$ in proton-proton collisions at the Large Hadron Collider. By incorporating final-state partonic and hadronic interactions through cascade models among jet shower partons and final hadrons, we investigate and compare to the CMS experimental data on multiplicity distribution, pseudorapidity distribution, and elliptic anisotropy coefficient $v_2^j$ of two-particle correlations within the jet. We show that final-state partonic interactions are essential for producing the flow-like long-range correlation, which leads to the enhanced tail in the $N_{\mathrm{ch}}^j$ dependence of $v_2^j$ above the non-flow correlation from jet parton showering at high multiplicities ($N_{\mathrm{ch}}^j\gtrsim 70$) as observed in the CMS experimental data. In addition, we provide predictions for the pseudorapidity-gap dependence of $v_2^j$ that can be tested in future experimental measurements.

   ↳ hep-phnucl-exnucl-th11 citations
4. 04*

   Extracting transition generalized parton distributions from hard exclusive pion-nucleon scattering

   Jian-Wei Qiu🇺🇸 · Zhite Yu🇺🇸

   We study the extraction of transition generalized parton distributions (GPDs) from production of two back-to-back high transverse momentum photons ($\gamma \gamma$) and a massive pair of leptons (${\ell }^{+}{\ell }^{-}$) in hard exclusive pion-nucleon scattering. We argue that the exclusive scattering amplitude of both processes could be factorized into nonperturbative pion distribution amplitude and nucleon transition GPDs that are convoluted with perturbatively calculable short-distance matching coefficients. We demonstrate that the exclusive diphoton production not only is complementary to the Drell-Yan-type dilepton production for extracting the GPDs, but also provides enhanced sensitivities for extracting the parton momentum fraction $x$ dependence of the GPDs. We show that both exclusive observables are physically measurable at the J-PARC and AMBER experiment energies. If the target nucleon can be polarized, corresponding spin asymmetries can offer additional sensitivities for extracting transition GPDs.

   ↳ hep-phhep-exhep-latnucl-ex+1PRD(2024)·22 citations
5. 05*

   Neutron star matter as a dilute solution of protons in neutrons

   J. Keller🇩🇪 · K. Hebeler🇩🇪 · C. J. Pethick🇺🇸 · A. Schwenk🇩🇪

   Neutron stars contain neutron-rich matter with around 5% protons at nuclear saturation density. In this Letter, we consider equilibrium between bulk phases of matter based on asymmetric nuclear matter calculations using chiral effective field theory interactions rather than, as has been done in the past, by interpolation between the properties of symmetric nuclear matter and pure neutron matter. Neutron drip (coexistence of nuclear matter with pure neutrons) is well established, but from earlier work it is unclear whether proton drip (equilibrium between two phases, both of which contain protons and neutrons) is possible. We find that proton drip is a robust prediction of any physically reasonable equation of state, but that it occurs over a limited region of densities and proton fractions. An analytical model based on expanding the energy in powers of the proton density, rather than the neutron excess, is able to account for these features of the phase diagram.

   ↳ nucl-thastro-ph.HEnucl-exPRL(2024)·11 citations
6. 06*

   First (calibration) experiment using proton beam from FRENA at SINP

   C. Basu · K. Banerjee · T. K. Ghosh · G. Mukherjee · C. Bhattacharya · Shraddha S Desai · R. Shil · A. K. Saha · J. K. Meena · T. Bar · D. Basak · L.K. Sahoo and 14 other authors

   This work presents the first calibration experiment of a 3 MV Tandetron accelerator, FRENA, performed in May 2022. The ${}^7$Li(p,n) reaction threshold was measured to calibrate the terminal voltage measuring device. A LiF target of thickness 175 $\mu$g/cm${}^2$ was used in the experiment. The measured threshold was 1872$\pm$2.7 keV, indicating 6$-$10 keV energy shift.

   ↳ physics.ins-detnucl-exphysics.acc-ph1 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.