Tue·Dec 20, 2022Tuesday·December 20, 2022

1. 01*

   J/$\psi$ and $\psi$(2S) Production in Small Systems with PHENIX

   Krista Smith (for the PHENIX Collaboration)🇺🇸

   The suppression of the $\psi$(2S) nuclear modification factor has been seen as a trademark signature of final state effects in large collision systems for decades. In small systems, deviations of the nuclear modification from unity had been attributed to cold nuclear matter effects until the observation of strong differential suppression of the $\psi$(2S) state in $p/d+$A collisions, which suggests the presence of final state effects. In this paper, we present results of J/$\psi$ and $\psi$(2S) measurements in the dimuon decay channel for $p+p$, $p+$Al, and $p+$Au collision systems at $\sqrt{s_{{}_{NN}}}$ = 200 GeV. Key results include the nuclear modification factors $R_{pA}$ as a function of centrality and rapidity. The measurements are compared with shadowing and transport model predictions, as well as to complementary measurements at LHC energies.

   nucl-exActa Phys.Polon.Supp.(2023)·1 citation
2. 02*

   Comment on "Compton Scattering Spectrum for Si and Ge Systems", by Chen-Kai Qiao et al. DOI 10.1088/1361-6471/ab5e35

   Kahane Sylvian

   It is pointed out that theoretical prediction in a paper published in 2020 were experimentally verified some 50 years ago.

   nucl-ex0 citations
3. 03*

   Measurement of medium-induced modification of jet yield and acoplanarity using semi-inclusive ${\gamma }_{\text{dir}}$+jet and ${\pi }^0$+jet distributions in $p$+$p$ and central Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV by STAR

   Derek Anderson (for the STAR Collaboration)🇺🇸

   The STAR collaboration presents measurements of semi-inclusive distributions of charged jets recoiling from high transverse energy ($E_{\text{T}}$) direct photon and ${\pi }^0$ triggers in $p$+$p$ and central Au+Au collisions at $\sqrt{s_{\text{NN}}}=200$ GeV. Jets are reconstructed from charged particles using the anti-$k_{\text{T}}$ algorithm with jet resolution parameters $R=0.2$ and 0.5. The large uncorrelated background in central Au+Au collisions is corrected using a mixed-event technique. This enables a jet measurement extending to low transverse momentum and large $R$ with well-controlled systematic uncertainties. We present measurements of the jet $R$ dependence of suppression, intra-jet broadening, and acoplanarity of ${\pi }^0$+jet and ${\gamma }_{\text{dir}}$+jet for trigger $E_{\text{T}}$ ($E_{\text{T}}^{\text{trig}}$) between $9-20$ GeV.

   nucl-exActa Phys.Polon.Supp.(2023)·6 citations
4. 04*

   Nuclear modification of hard scattering processes in small systems at PHENIX

   Niveditha Ramasubramanian🇺🇸 · Gabor David🇺🇸

   Collisions of small systems at RHIC exhibit a significant suppression of the nuclear modification factor $R_{xA}$ of jets and high momentum neutral pions in events with large event activity. This suppression is accompanied by an enhancement of $R_{xA}$ in events with low event activity. Since event activity is commonly interpreted as a measure of the centrality of the collisions, these results call into question any interpretation of the suppression in central collisions that invokes energy loss in a QGP produced small systems. In this talk, we will compare prompt photon to ${\pi }^0$ production measured by PHENIX in d+Au collision at $\sqrt{s}=200GeV$ to demonstrate that the apparent centrality dependence is not related to a nuclear modification of hard scattering processes, but likely due to deviations from the proportionality of event activity and centrality in the underlying standard Glauber model calculations. Furthermore, we will use prompt photon production in d+Au relative to p+p collisions to empirically determine the effective number of binary collisions $N_{coll}$ of a given event sample. We find that for all event selections, except for those with the highest event activity, $R_{xA}$ of ${\pi }^0$ is consistent with unity. By comparing p+Au and d+Au collisions, we will investigate the significance of the remaining suppression of high $p_T$ ${\pi }^0$ production in events with high event activity.

   nucl-ex0 citations
5. 05*

   Hot Spot model of Nucleon and Double Parton Scattering

   B. Blok (Technion)🇮🇱 · R. Segev (Technion)🇮🇱 · M. Strikman (Penn State University)🇺🇸

   We calculate the rate of double parton scattering (DPS) in proton - proton collisions in the framework of the recently proposed hot spot model of the nucleon structure. The resulting rate, especially for the case of three hot spots, appears to be in tension with the current experimental data on DPS at the LHC.

   ↳ hep-phhep-exnucl-exnucl-thEPJC(2023)·4 citations
6. 06*

   Nucleon resonances and transition form factors

   Volker D. Burkert🇺🇸

   This is a contribution to the review 50 Years of Quantum Chromodynamics edited by F. Gross and E. Klempt, to be published in Journal EPJC. This contribution reviews the nucleon resonance transition form factors determined from meson electro-production experiments at electron accelerator facilities, i.e. this contribution focuses on space-like transition form factors and amplitudes. Comparisons are made when available to LQCD and to approaches with traceable links to strong QCD and to advanced quark model calculations

   ↳ hep-phhep-latnucl-ex9 citations
7. 07*

   A Powerful New Energy Density Functional

   Anthony W Thomas🇦🇺 · Pierre A M Guichon🇫🇷 · Jesper Leong🇦🇺 · K L Martinez-Paglinawan · J R Stone🇬🇧

   We describe the most recent energy density functional derived within the quark meson coupling model. Although fit to the binding energies and charge radii of just seventy magic nuclei, the accuracy with which it reproduces nuclear properties across the entire periodic table is outstanding. As well as outlining a number of those results, we present an argument explaining why having a physically motivated model with a small number of parameters is especially desirable as one seeks to make predictions in new regions of N and Z. As an example we show the predictions for known super-heavy nuclei that were not included in the fit.

   ↳ nucl-thhep-phnucl-exJ.Phys.Conf.Ser.(2023)·2 citations
8. 08*

   Bose-Einstein Condensation and Dissipative Dynamics in a Relativistic Pion Gas

   Kshitish Kumar Pradhan🇮🇳 · Dushmanta Sahu🇮🇳 · Captain R. Singh🇮🇳 · Raghunath Sahoo🇮🇳

   Pion condensation in ultra-relativistic collisions presents a compelling theoretical phenomenon with significant implications for the dynamics of hadronic matter. Various theoretical frameworks offer insight into the nature of high-temperature Bose-Einstein condensation (BEC). The present study investigates the dissipative behavior of a relativistic pion gas undergoing Bose-Einstein condensation (BEC) in ultra-relativistic heavy-ion collisions. Further, we obtain viscosity ($\eta$), bulk viscosity ($\zeta$), and speed of sound ($c_s$) by employing the Boltzmann transport equation with the relaxation time approximation. Findings show a substantial drop in $\eta /s$ and $\zeta /s$ with the fractional increase in condensation. This effect is becoming more evident in larger systems approaching the thermodynamic limit. Alongside the reduction in viscosities, the speed of sound also decreases with increasing condensation, indicating a softening of the equation of state. The analysis of finite-size effects reveals that larger systems exhibit more pronounced signatures of BEC. These results suggest that pion condensation can influence the hydrodynamic evolution of the hadronic phase in heavy-ion collisions, with consequential implications for interpreting collective flow observables and the underlying equation of state.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2025)·4 citations
9. 09*

   Study of a possible silicon photomultiplier based readout of the large plastic scintillator neutron detector NeuLAND

   Thomas Hensel🇩🇪 · David Weinberger · Daniel Bemmerer🇩🇪 · Konstanze Boretzky · Igor Gašparić🇭🇷 · Daniel Stach · Andreas Wagner🇩🇪 · Kai Zuber🇩🇪

   The NeuLAND (New Large-Area Neutron Detector) plastic-scintillator-based time-of-flight detector for 0.1-1.6 GeV neutrons is currently under construction at the Facility for Antiproton and Ion Research (FAIR), Darmstadt, Germany. In its final configuration, NeuLAND will consist of 3000 2.7 m $\times$ 5 cm $\times$ 5 cm big plastic scintillator bars that are read out on each end by fast timing photomultipliers. Here, data from a comprehensive study of an alternative light readout scheme using silicon photomultipliers (SiPM) are reported. For this purpose, a NeuLAND bar was instrumented on each end with a SiPM-based prototype of the same geometry as a 1'' photomultiplier tube, including four 6 $\times$ 6 mm${}^2$ SiPMs, amplifiers, high voltage supply, and microcontroller. Tests were carried out using the 35 MeV electron beam from the superconducting Electron Linac for beams with high Brilliance and low Emittance (ELBE) with its picosecond-level time jitter in two different modes of operation, namely parasitic mode with one electron per bunch and single-user mode with 1-60 electrons per bunch. Acqiris fast digitisers were used for data acquisition. In addition, off-beam tests using cosmic rays and the NeuLAND data acquisition scheme have been carried out. Typical time resolutions of ${\sigma }_t\le$ 120 ps were found for $\ge$95% efficiency for minimum ionising particles, improving on previous work at ELBE and exceeding the NeuLAND timing goal of ${\sigma }_t$ < 150 ps. Over a range of 10-300 MeV deposited energy in the NeuLAND bar, the gain was found to deviate by $\le$10% ($\le$20%) from linearity for 35 mm (75 mm) SiPM pitch, respectively, satisfactory for calorimetric use of the full NeuLAND detector. The dark rate of the prototype studied was found to be lower than the expected cosmic-ray induced background in NeuLAND.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2023)·0 citations
10. 10*

    Inspection of the detection cross section dependence of the Gallium Anomaly

    C. Giunti🇮🇹 · Y.F. Li🇨🇳 · C.A. Ternes🇮🇹 · Z. Xin🇨🇳

    We discuss in detail the dependence of the Gallium Anomaly on the detection cross section. We provide updated values of the size of the Gallium Anomaly and find that its significance is larger than about $5\sigma$ for all the detection cross section models. We discuss the dependence of the Gallium Anomaly on the assumed value of the half life of ${}^{71}\text{Ge}$, which determines the cross sections of the transitions from the ground state of ${}^{71}\text{Ga}$ to the ground state of ${}^{71}\text{Ge}$. We show that a value of the ${}^{71}\text{Ge}$ half life which is larger than the standard one can reduce or even solve the Gallium Anomaly. Considering the short-baseline neutrino oscillation interpretation of the Gallium Anomaly, we show that a value of the ${}^{71}\text{Ge}$ half life which is larger than the standard one can reduce the tension with the results of other experiments. Since the standard value of the ${}^{71}\text{Ge}$ half life was measured in 1985, we advocate the importance of new measurements with modern technique and apparatus for a better assessment of the Gallium Anomaly.

    ↳ hep-phhep-exnucl-exnucl-thPLB(2023)·27 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.