Wed·Sep 16, 2020Wednesday·September 16, 2020

1. 01*

   Strangeness production with respect to high momentum hadrons in pp and p-Pb collisions with ALICE at the LHC

   Justin Blair (on behalf of the ALICE Collaboration)🇺🇸

   In order to understand strangeness production mechanisms, one can study the correlations of hadrons with hidden strangeness (e.g. the $\varphi$ meson) and open strangeness (${\mathrm{K}}_{\mathrm{S}}^0$, $\Lambda$ and $\bar{\Lambda }$) in hard (jet) processes and in soft (bulk) processes. Two-particle angular correlations with ${\mathrm{K}}_{\mathrm{S}}^0$ triggers allow for the study of fragmentation in pp collisions as a function of multiplicity. Similarly, correlations with associated $\varphi$ mesons in p-Pb collisions allow both the jet and the underlying event components of strange particle production to be probed. Presented are ${\mathrm{K}}_{\mathrm{S}}^0$-h correlations measured by ALICE in pp collisions at $\sqrt{s}=13$ TeV, and h-$\varphi$ correlations measured in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV.

   nucl-exSpringer Proc.Phys.(2020)·1 citation
2. 02*

   Jet substructure measurements in $\mathrm{p}\mathrm{p}$ and $\text{mbox}Pb-Pb$ collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with ALICE

   James Mulligan (for the ALICE Collaboration)🇺🇸

   We report jet substructure measurements in $\mathrm{p}\mathrm{p}$ and $\text{mbox}Pb-Pb$ collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with the ALICE detector. Charged-particle jets were reconstructed at midrapidity with the ALICE tracking detectors using the anti-$k_{\mathrm{T}}$ algorithm with resolution parameters $R=0.2$ and $R=0.4$. In $\mathrm{p}\mathrm{p}$ collisions, the groomed jet momentum fraction, $z_{\mathrm{g}}$, and the groomed jet radius, ${\theta }_{\mathrm{g}}\equiv R_{\mathrm{g}}/R$, are measured for the first time using the Dynamical Grooming method. Additionally, new systematic measurements of the infrared and collinear (IRC) safe ungroomed jet angularities are presented. In heavy-ion collisions, we measure $z_{\mathrm{g}}$ and ${\theta }_{\mathrm{g}}$ with the Soft Drop grooming algorithm. The large underlying event in heavy-ion collisions poses a challenge for the reconstruction of groomed jet observables, since fluctuations in the background can cause groomed splittings to be misidentified. By using strong grooming conditions to reduce this background, we report these observables fully corrected for detector effects and background fluctuations for the first time, and compare them to several theoretical models.

   nucl-exhep-exPoS(2021)·6 citations
3. 03*

   Measuring the surface thickness of the weak charge density of nuclei

   Brendan Reed🇺🇸 · Z. Jaffe🇺🇸 · C. J. Horowitz🇺🇸 · C. Sfienti🇩🇪

   The present PREX-II and CREX experiments are measuring the rms radius of the weak charge density of ${}^{208}$Pb and ${}^{48}$Ca. We discuss the feasibility of a new parity violating electron scattering experiment to measure the surface thickness of the weak charge density of a heavy nucleus. Once PREX-II and CREX have constrained weak radii, an additional parity violating measurement at a momentum transfer near 0.76 fm${}^{-1}$ for ${}^{208}$Pb or 1.28 fm${}^{-1}$ for ${}^{48}$Ca can determine the surface thickness.

   ↳ nucl-thnucl-exPRC(2020)·16 citations
4. 04*

   An all-digital associated particle imaging system for the 3D determination of isotopic distributions

   Mauricio Ayllon Unzueta · Bernhard Ludewigt🇺🇸 · Brian Mak · Tanay Tak · Arun Persaud🇺🇸

   Associated particle imaging (API) is a non-destructive nuclear technique for the 3D determination of isotopic distributions. By detecting the alpha particle associated with the emitted neutron in the deuterium-tritium fusion reaction with a position- and time-resolving detector, the direction of the 14.1 MeV neutron and its time of emission can be determined. Employing this method, isotope characteristic gamma rays emitted in inelastic neutron scattering events can be correlated with the neutron interaction location. An API system consisting of a sealed-type neutron generator, gamma detectors, and a position-sensitive alpha detector was designed, constructed, and characterized. The system was tested with common soil elements and shown to be sensitive to 12C, 16O, 28Si, 27Al, and 56Fe. New aspects of our approach are the use of a yttrium-aluminum-perovskite (YAP) scintillator, using a sapphire window instead of a fiber-optic faceplate for light transport to the photomultiplier, and the all-digital data acquisition system. We present a description of the system with simulations and experimental results that show a position resolution on the alpha detector of 1 mm, a depth resolution using a LaBr3 detector of 6.2 cm, and an angular resolution of 4.5 degrees. Additionally, we present single-element gamma response measurements for the elements mentioned above together with a comparison to Monte Carlo simulations (MCNP6).

   ↳ physics.ins-detnucl-exRev.Sci.Instrum.(2021)·4 citations
5. 05*

   A primary electron beam facility at CERN -- eSPS Conceptual design report

   M. Aicheler🇨🇭 · T. Akesson🇸🇪 · F. Antoniou🇨🇭 · A. Arnalich🇨🇭 · P. A. Arrutia Sota🇨🇭 · P. Bettencourt Moniz Cabral🇨🇭 · D. Bozzini🇨🇭 · M. Brugger🇨🇭 · O. Brunner🇨🇭 · P. N. Burrows🇬🇧 · R. Calaga🇨🇭 · M. J. Capstick🇨🇭 and 43 other authors

   The design of a primary electron beam facility at CERN is described. The study has been carried out within the framework of the wider Physics Beyond Colliders study. It re-enables the Super Proton Synchrotron (SPS) as an electron accelerator, and leverages the development invested in Compact Linear Collider (CLIC) technology for its injector and as an accelerator research and development infrastructure. The facility would be relevant for several of the key priorities in the 2020 update of the European Strategy for Particle Physics, such as an electron-positron Higgs factory, accelerator R\&D, dark sector physics, and neutrino physics. In addition, it could serve experiments in nuclear physics. The electron beam delivered by this facility would provide access to light dark matter production significantly beyond the targets predicted by a thermal dark matter origin, and for natures of dark matter particles that are not accessible by direct detection experiments. It would also enable electro-nuclear measurements crucial for precise modelling the energy dependence of neutrino-nucleus interactions, which is needed to precisely measure neutrino oscillations as a function of energy. The implementation of the facility is the natural next step in the development of X-band high-gradient acceleration technology, a key technology for compact and cost-effective electron/positron linacs. It would also become the only facility with multi-GeV drive bunches and truly independent electron witness bunches for plasma wakefield acceleration. A second phase capable to deliver positron witness bunches would make it a complete facility for plasma wakefield collider studies. [...]

   ↳ physics.acc-phhep-exnucl-ex9 citations
6. 06*

   Beam Energy dependence of Light Nuclei Production in Au+Au Collisions

   Wenbin Zhao🇨🇳 · Chun Shen🇺🇸 · Che Ming Ko🇺🇸 · Quansheng Liu🇨🇳 · Huichao Song🇨🇳

   We study the collision energy dependence of (anti-)deuteron and (anti-)triton production in the most central Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=$ 7.7, 11.5, 19.6, 27, 39, 62.4 and 200 GeV, using the nucleon coalescence model. The needed phase-space distribution of nucleons at the kinetic freeze-out is generated from a new 3D hybrid dynamical model (\texttt{iEBE-MUSIC}) by using a smooth crossover equation of state (EoS) without a QCD critical point. Our model calculations predict that the coalescence parameters of (anti-)deuteron ($B_2(d)$ and $B_2(\bar{d})$) decrease monotonically as the collision energy increases, and the light nuclei yield ratio $N_t{N}_p/N_d^2$ remains approximately a constant with respect to the collision energy. These calculated observables fail to reproduce the non-monotonic behavior of the corresponding data from the STAR Collaboration. Without including any effects of the critical point in our model, our results serve as the baseline predictions for the yields of light nuclei in the search for the possible QCD critical points from the experimental beam energy scan of heavy ion collisions.

   ↳ nucl-thhep-phnucl-exPRC(2020)·48 citations
7. 07*

   Studies of charm and beauty hadron long-range correlations in pp and pPb collisions at LHC energies

   CMS Collaboration

   Measurements of the second Fourier harmonic coefficient ($v_2$) of the azimuthal distributions of prompt and nonprompt D${}^0$ mesons produced in pp and pPb collisions are presented. Nonprompt D${}^0$ mesons come from beauty hadron decays. The data samples are collected by the CMS experiment at nucleon-nucleon center-of-mass energies of 13 and 8.16 TeV, respectively. In high multiplicity pp collisions, $v_2$ signals for prompt charm hadrons are reported for the first time, and are found to be comparable to those for light-flavor hadron species over a transverse momentum ($p_{\mathrm{T}}$) range of 2-6 GeV. Compared at similar event multiplicities, the prompt D${}^0$ meson $v_2$ values in pp and pPb collisions are similar in magnitude. The $v_2$ values for open beauty hadrons are extracted for the first time via nonprompt D${}^0$ mesons in pPb collisions. For $p_{\mathrm{T}}$ in the range of 2-5 GeV, the results suggest that $v_2$ for nonprompt D${}^0$ mesons are smaller than those for prompt D${}^0$ mesons. These new measurements indicate a positive charm hadron $v_2$ in pp collisions and suggest a mass dependence in $v_2$ between charm and beauty hadrons in the pPb system. These results provide insights into the origin of heavy-flavor quark collectivity in small systems.

   ↳ hep-exnucl-exPLB(2021)·67 citations
8. 08*

   Inclusive Electron Scattering And The GENIE Neutrino Event Generator

   A. Papadopoulou🇺🇸 · A. Ashkenazi🇺🇸 · S. Gardiner🇺🇸 · M. Betancourt🇺🇸 · S. Dytman🇺🇸 · L.B. Weinstein🇺🇸 · E. Piasetzky🇮🇱 · F. Hauenstein🇺🇸 · M. Khachatryan🇺🇸 · S. Dolan🇨🇭 · G. Megias🇯🇵 · O. Hen (The electrons for neutrinos collaboration)🇺🇸

   The extraction of neutrino mixing parameters from accelerator-based neutrino oscillation experiments relies on proper modeling of neutrino-nucleus scattering processes using neutrino-interaction event generators. Experimental tests of these generators are difficult due to the broad range of neutrino energies produced in accelerator-based beams and the low statistics of current experiments. Here we overcome these difficulties by exploiting the similarity of neutrino and electron interactions with nuclei to test neutrino event generators using high-precision inclusive electron scattering data. To this end, we revised the electron-scattering mode of the GENIE event generator ($e$-GENIE) to include electron-nucleus bremsstrahlung radiation effects and to use, when relevant, the exact same physics models and model parameters, as the standard neutrino-scattering version. We also implemented new models for quasielastic (QE) scattering and meson exchange currents (MEC) based on the theory-inspired SuSAv2 approach. Comparing the new $e$-GENIE predictions with inclusive electron scattering data, we find an overall adequate description of the data in the QE- and MEC-dominated lower energy transfer regime, especially when using the SuSAv2 models. Higher energy transfer-interactions, which are dominated by resonance production, are still not well modeled by $e$-GENIE.

   ↳ nucl-thhep-exhep-phnucl-exPRD(2021)·48 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.