Tue·Oct 12, 2021Tuesday·October 12, 2021

1. 01*

   Extension of the J-PARC Hadron Experimental Facility: Third White Paper

   Kazuya Aoki🇯🇵 · Hiroyuki Fujioka🇯🇵 · Toshiyuki Gogami🇯🇵 · Yoshimasa Hidaka🇯🇵 · Emiko Hiyama🇯🇵 · Ryotaro Honda🇯🇵 · Atsushi Hosaka🇯🇵 · Yudai Ichikawa🇯🇵 · Masaharu Ieiri🇯🇵 · Masahiro Isaka🇯🇵 · Noriyoshi Ishii🇯🇵 · Takatsugu Ishikawa🇯🇵 and 31 other authors

   The J-PARC Hadron Experimental Facility was constructed with an aim to explore the origin and evolution of matter in the universe through the experiments with intense particle beams. In the past decade, many results on particle and nuclear physics have been obtained at the present facility. To expand the physics programs to unexplored regions never achieved, the extension project of the Hadron Experimental Facility has been extensively discussed. This white paper presents the physics of the extension of the Hadron Experimental Facility for resolving the issues in the fields of the strangeness nuclear physics, hadron physics, and flavor physics.

   nucl-exhep-exnucl-thphysics.ins-det131 citations
2. 02*

   Observation of a structure in the M${}_{p\eta }$ invariant mass distribution near 1700 MeV/$c^2$ in the $\gamma \mathbf{p}\to \mathbf{p}{\pi }^0\eta$ reaction

   V. Metag🇩🇪 · M. Nanova🇩🇪 · J. Hartmann🇩🇪 · P. Mahlberg🇩🇪 · F. Afzal🇩🇪 · C. Bartels🇩🇪 · D. Bayadilov🇩🇪 · R. Beck🇩🇪 · M. Becker🇩🇪 · E. Blanke🇩🇪 · K.-T. Brinkmann🇩🇪 · S. Ciupka🇩🇪 and 65 other authors

   The reaction $\gamma p\to p{\pi }^0\eta$ has been studied with the CBELSA/TAPS detector at the electron stretcher accelerator ELSA in Bonn for incident photon energies from threshold up to 3.1 GeV. This paper has been motivated by the recently claimed observation of a narrow structure in the M${}_{N\eta }$ invariant mass distribution at a mass of 1678 MeV/$c^2$. The existence of this structure cannot be confirmed in the present work. Instead, for E${}_{\gamma }$ = 1400 - 1500 MeV and the cut M${}_{p{\pi }^0}\le 1190$ MeV/$c^2$ a statistically significant structure in the M${}_{p\eta }$ invariant mass distribution near 1700 MeV/$c^2$ is observed with a width of $\Gamma \approx 35$ MeV/$c^2$ while the mass resolution is ${\sigma }_{res}$ = 5 MeV/$c^2$. Increasing the incident photon energy from 1420 to 1540 MeV this structure shifts in mass from $\approx$ 1700MeV/c${}^2$ to $\approx$ 1725 MeV/$c^2$; the width increases to about 50 MeV/$c^2$ and decreases thereafter. The cross section associated with this structure reaches a maximum of $\approx$ 100 nb around E${}_{\gamma }\approx$ 1490 MeV (W $\approx$ 1920 MeV), which coincides with the $p{a}_0$ threshold. Three scenarios are discussed which might be the origin of this structure in the M${}_{p\eta }$ invariant mass distribution. The most likely interpretation is that it is due to a triangular singularity in the $\gamma p\to p{a}_0\to p{\pi }^0\eta$ reaction

   nucl-exnucl-thEPJA(2021)·12 citations
3. 03*

   Jet substructure measurements in heavy-ion collisions with ALICE

   James Mulligan (for the ALICE Collaboration)🇺🇸

   Jet substructure, defined by observables constructed from the distribution of constituents within a jet, provides the versatility to tailor observables to specific regions of QCD radiation phase space. This flexibility provides exciting new opportunities to study jet quenching in heavy-ion collisions and to ultimately help reveal the nature of the quark-gluon plasma. The ALICE detector is particularly well-suited to jet substructure measurements in heavy-ion collisions due to its high-precision tracking system. In these proceedings, we report several new jet substructure measurements in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with ALICE. These include the first fully corrected measurements of the groomed jet momentum splitting fraction, $z_{\mathrm{g}}$, and the groomed jet radius, ${\theta }_{\mathrm{g}}\equiv R_{\mathrm{g}}/R$, as well as $N$-subjettiness and the fragmentation distribution of reclustered sub-jets. These measurements are compared to theoretical calculations and provide new constraints on the physics underlying jet quenching.

   nucl-exhep-exPoS(2022)·2 citations
4. 04*

   Probing gluon helicity with heavy flavor at the EIC

   Daniele Paolo Anderle🇨🇳 · Xin Dong🇺🇸 · Felix Hekhorn🇮🇹 · Matthew Kelsey🇺🇸 · Sooraj Radhakrishnan🇺🇸 · Ernst Sichtermann🇺🇸 · Lei Xia🇨🇳 · Hongxi Xing🇨🇳 · Feng Yuan🇺🇸 · Yuxiang Zhao🇨🇳

   We propose a new measurement of the heavy flavor hadron double spin asymmetry in deep-inelastic scattering at a future Electron-Ion Collider (EIC) to constrain the polarized gluon distribution function inside the proton. Statistical projection on $D^0$ meson double spin asymmetry is calculated with an EIC central detector using an all-silicon tracker and vertexing subsystem. A first impact study was done by interpreting pseudo-data at next-to-leading order in QCD. The sensitivity of the experimental observable in constraining gluon helicity distribution in a wide range of parton momentum fraction $x$ has been investigated considering different beam energy configurations. This measurement complements the inclusive spin-dependent structure function measurement and provides an opportunity to constrain the gluon helicity distribution in the moderate $x$ region.

   ↳ hep-exhep-phnucl-exnucl-thPRD(2021)·11 citations
5. 05*

   System evolution of forward-backward multiplicity correlations in a multi-phase transport model

   Yi-An Li🇨🇳 · Dong-Fang Wang🇨🇳 · Song Zhang🇨🇳 · Yu-Gang Ma🇨🇳

   The initial geometry effect on forward-backward multiplicity correlations $C(N_f,N_b)$ is studied in relativistic collisions between light nuclei by using a multiphase transport model (AMPT). It is found that tetrahedron ${}^{16}$O + ${}^{16}$O gives a more uniform and symmetrical fireball which produces a more isotropic distribution of final particles after the expansion and evolution, and leads to a small $C(N_f,N_b)$. Forward-backward multiplicity correlation could be taken as a useful probe to distinguish the pattern of $\alpha$-clustered ${}^{16}$O in experiments by comparing the neighboring colliding nuclear systems like ${}^{14}$N + ${}^{14}$N and ${}^{19}$F + ${}^{19}$F.

   ↳ hep-phnucl-exnucl-thPRC(2021)·17 citations
6. 06*

   Measurements of neutron fields in a wide energy range using multi-foil activation analysis

   D. Chiesa🇮🇹 · C. Cazzaniga · M. Nastasi🇮🇹 · M. Rebai · C. D. Frost · G. Gorini · S. Lilley · S. Pozzi🇮🇹 · E. Previtali🇮🇹

   An accurate characterization of the neutron fields at spallation sources is crucial for many applications based on neutron irradiations, such as radiation damage tests that need a precise dose estimate. In this work we present the neutron flux measurements performed with the multi-foil activation technique in the ROTAX and ChipIr beamlines of the ISIS spallation source, characterized by moderated and unmoderated spectra, respectively. We selected many different activation reactions to cover a wide energy range, from thermal to very fast neutrons up to about 100 MeV. By applying a Bayesian unfolding algorithm, we demonstrate the effectiveness of this technique in measuring the neutron flux intensity and energy spectrum with precision and accuracy.

   ↳ physics.ins-detnucl-exIEEE Trans.Nucl.Sci.(2022)·4 citations
7. 07*

   Probing the Gluon Plasma with Charm Balance Functions

   Sumit Basu🇸🇪 · Peter Christiansen🇸🇪 · Alice Ohlson🇸🇪 · David Silvermyr🇸🇪

   Recent theoretical explanations for how hydrodynamic-like flow can build up quickly in small collision systems (hydrodynamization) has led to a microscopic picture of flow building up in a gluon-dominated phase before chemical equilibrium between quarks and gluons has been attained. The goal of this contribution to Offshell-2021 is to explore consequence of assuming a long-lived gluon-dominated phase, which we shall denote a gluon plasma (GP). As these consequences are naturally enhanced in a large systems, we assume and explore the extreme scenario in which a GP would be created in AA collisions and exist for significant time before the formation of a chemically-equilibrated quark-gluon plasma (QGP). The GP and its formation would be impossible to probe with light-quark hadrons, which are first produced later in this scenario. As charm quarks are produced early in the collision, they can circumvent the limitations of light quarks and we propose charm balance functions as an effective tool to test this idea and constrain the dynamics of the GP.

   ↳ hep-phhep-exnucl-exEPJC(2021)·4 citations
8. 08*

   Measurements of inclusive photons at forward rapidities in p-Pb collisions at $\sqrt{s{}_{\mathrm{NN}}}$ = 5.02 TeV with ALICE

   Abhi Modak (for the ALICE Collaboration)🇮🇳

   We present multiplicity and pseudorapidity distributions of inclusive photons at forward rapidity in proton-lead (p-Pb) collisions at $\sqrt{s{}_{\mathrm{NN}}}$ = 5.02 TeV using the data obtained from Photon Multiplicity Detector (PMD) of ALICE. The centrality dependence of pseudorapidity distributions of inclusive photons is also studied. Results are compared with the previous ALICE measurements of charged-particle production and with theoretical predictions from Monte Carlo models, DPMJET and HIJING.

   ↳ hep-exnucl-exPoS(2021)·2 citations
9. 09*

   Nonperturbative two-pion exchange contributions to the nucleon-nucleon interaction in covariant baryon chiral perturbation theory

   Chun-Xuan Wang🇨🇳 · Jun-Xu Lu🇨🇳 · Yang Xiao🇨🇳 · Li-Sheng Geng🇨🇳

   We calculate the nonperturbative two-pion exchange (TPE) contributions to the $NN$ interaction in covariant baryon chiral perturbation theory. We study how the nonperturbative resummation affects the $NN$ phase shifts for partial waves with $J\ge 3$ and $L\le 6$. No significant differences are observed between the nonperturbative phase shifts and perturbative ones for most partial waves except for ${}^3{D}_3$, for which the nonperturbative resummation greatly improves the description of the phase shifts. However, a significant cutoff dependence is found for this partial wave and a reasonable description of the phase shifts can only be obtained with a particular cutoff. Furthermore, we compare the so-obtained nonperturbative phase shifts with those obtained in the heavy baryon chiral perturbation theory. We show that the contributions from relativistic nonperturbative TPE are more moderate than those from the nonrelativistic TPE obtained in the dimensional regularization scheme. A proper convergence pattern is observed for most of the partial waves studied except for ${}^3{F}_3$, ${}^3{F}_4$, and ${}^3{H}_6$, for which the subleading TPE contributions are a bit strong. We find that for $H$ and $I$ partial waves, the OPE alone can already describe the phase shifts reasonably well.

   ↳ nucl-thhep-exhep-lathep-ph+1PRC(2022)·14 citations
10. 10*

    Reconstructing the Kinematics of Deep Inelastic Scattering with Deep Learning

    Miguel Arratia🇺🇸 · Daniel Britzger🇩🇪 · Owen Long🇺🇸 · Benjamin Nachman🇺🇸

    We introduce a method to reconstruct the kinematics of neutral-current deep inelastic scattering (DIS) using a deep neural network (DNN). Unlike traditional methods, it exploits the full kinematic information of both the scattered electron and the hadronic-final state, and it accounts for QED radiation by identifying events with radiated photons and event-level momentum imbalance. The method is studied with simulated events at HERA and the future Electron-Ion Collider (EIC). We show that the DNN method outperforms all the traditional methods over the full phase space, improving resolution and reducing bias. Our method has the potential to extend the kinematic reach of future experiments at the EIC, and thus their discovery potential in polarized and nuclear DIS.

    ↳ hep-exhep-phnucl-exNucl.Instrum.Meth.A(2022)·30 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.