Mon·Aug 9, 2021Monday·August 9, 2021

1. 01*

   Threshold Upsilon-meson Photoproduction at EIC and EicC

   Igor I. Strakovsky (GW)🇺🇸 · William J. Briscoe (GW)🇺🇸 · Lubomir Pentchev (JLab)🇺🇸 · Axel Schmidt (GW)🇺🇸

   High-accuracy ${\rm Y}$-meson photoproduction data from EIC and EicC experiments will allow the measurement of the near-threshold total cross section of the reaction $\gamma p\to {\rm Y}p$, from which the absolute value of the ${\rm Y}p$ scattering length, $|{\alpha }_{{\rm Y}p}|$, can be extracted using a Vector-Meson Dominance model. For this evaluation, we used ${\rm Y}$-meson photoproduction quasi-data from the QCD approach (the production amplitude can be factorized in terms of gluonic generalized parton distributions and the quarkonium distribution amplitude). A comparative analysis of $|{\alpha }_{{\rm Y}p}|$ with the recently determined scattering lengths for $\omega p$, $\varphi p$, and $J/\psi p$ using the A2, CLAS, and GlueX experimental data are performed. The role of the "young" vector-meson effect is evaluated.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2021)·28 citations
2. 02*

   First results from a search for coherent elastic neutrino-nucleus scattering (CE$\nu$NS) at a reactor site

   J. Colaresi🇺🇸 · J.I. Collar🇺🇸 · T.W. Hossbach🇺🇸 · A.R.L. Kavner🇺🇸 · C.M. Lewis🇺🇸 · A.E. Robinson🇨🇦 · K.M. Yocum🇺🇸

   The deployment of a low-noise 3 kg p-type point contact germanium detector at the Dresden-II power reactor, 8 meters from its 2.96 GW${}_{th}$ core, is described. This location provides an unprecedented (anti)neutrino flux of 8.1$\times 10^{13}\overline{{\nu }_e}/$cm${}^2$s. When combined with the 0.2 keV${}_{ee}$ detector threshold achieved, a first measurement of CE$\nu$NS from a reactor source appears to be within reach. We report on the characterization and abatement of backgrounds during initial runs, deriving improved limits on extensions of the Standard Model involving a light vector mediator, from preliminary data.

   ↳ hep-exhep-phnucl-exphysics.app-phPRD(2021)·65 citations
3. 03*

   Application of the constituent quark exchange model to the parton distributions and the EMC ratios of ${}^{12}C$ and ${}^{14}N$ nuclei

   A. Hadian🇮🇷 · M.Modarres🇮🇷

   The quark exchange model (QEM) is reformulated for the $A=12$ and $14$ systems to obtain the constituent quark distributions of ${}^{12}C$ and ${}^{14}N$ nuclei, respectively. Afterwards, the different types of the point-like parton distribution functions (PDFs), i.e., the valence quarks, the sea quarks and the gluons, are extracted from the constituent quark model (CQM), at the hadronic scale $Q_0^2=0.34$ $Ge{V}^2$ to generate the constituent quark exchange model (CQEM = QEM $\oplus$ CQM) PDFs. From the resulted PDFs, the structure functions and the European Muon Collaboration (EMC) ratios of the above-mentioned nuclei at the appropriate hadronic scale are calculated. To make our results more comparable with the available experimental data, we evolve the PDFs, by using the standard DGALP evolution equations, to the higher hard scales. Subsequently, the EMC ratios of ${}^{12}C$ and ${}^{14}N$ nuclei at the some higher energy scales, corresponding to the scales of available data, are calculated, at the leading (LO) and the next-to-leading (NLO) orders of pQCD. By doing so, it is observed that the EMC ratios do not significantly depend on the hard scale $Q^2$, and the outcomes are consistent with the various experimental data such as HERMES, BCDMS, JLab, SLAC, NMC, and EMC. Especially, in the mid-range of Bjorken $x$ values, the results are so desirable. Like our previous works for the ${}^{4}He$ and ${}^{6}Li$ nuclei, we again observe that at a fixed scale $Q^2$, the LO and the NLO EMC ratios with high precision are approximately the same. Therefore, one can conclude that at a given hard scale, the LO approximation is good enough for calculating the EMC ratios of light nuclei.

   ↳ nucl-thhep-exhep-phhep-th+1NPA(2020)·2 citations
4. 04*

   Improved $\Lambda p$ Elastic Scattering Cross Sections Between 0.9 and 2.0 GeV/c and Connections to the Neutron Star Equation of State

   CLAS Collaboration: J. Rowley🇺🇸 · N. Compton🇺🇸 · C. Djalali🇺🇸 · K. Hicks🇺🇸 · J. Price🇺🇸 · N. Zachariou🇬🇧 · K.P. Adhikari🇺🇸 · W.R. Armstrong🇺🇸 · H. Atac🇺🇸 · L. Baashen🇺🇸 · L. Barion🇮🇹 · M. Bashkanov🇬🇧 and 133 other authors

   Strange matter is believed to exist in the cores of neutron stars based on simple kinematics. If this is true, then hyperon-nucleon interactions will play a significant part in the neutron star equation of state (EOS). Yet, compared to other elastic scattering processes, there is very little data on $\Lambda$-$N$ scattering. This experiment utilized the CLAS detector to study the $\Lambda p\to \Lambda p$ elastic scattering cross section in the incident $\Lambda$ momentum range 0.9-2.0 GeV/c. This is the first data on this reaction in several decades. The new cross sections have significantly better accuracy and precision than the existing world data, and the techniques developed here can also be used in future experiments.

   ↳ hep-exnucl-exPRL(2021)·53 citations
5. 05*

   Design of a novel compact neutron collimator

   Roberto Bedogni🇮🇹 · Marco Costa🇮🇹 · Elisabetta Durisi🇮🇹 · Francesco Grazzi🇮🇹 · Alessandro Lega · Ettore Mafucci🇮🇹 · Luca Menzio🇮🇹 · Valeria Monti🇮🇹 · Oriol Sans-Planell🇮🇹 · Lorenzo Visca🇮🇹

   In this work the concept of a novel slow neutron collimator and the way to operate it are presented. The idea is based on the possibility to decouple the device field-of-view from its collimation power. A multi-channel geometry is proposed consisting of a chess-board structure where highly neutron-absorbing channels are alternated to air channels. A borated polymer was purposely developed to produce the attenuating components in the form of square-sectioned long rods. A scalable structure consisting of multiple collimation sectors can be arranged. The geometrical parameter LD, corresponding to the ratio between the length of a channel and its width, defines the collimation power. Several sectors can be arranged one after the other to reach relevant collimation powers. Each sector, 100 mm long, is composed by several channels with D = 2.5 mm corresponding to an L/D coefficient of 40. The target field of view is 50x50 mm2. This novel collimator, developed inside the INFN-ANET collaboration, due to its intrinsic compactness, will be of great importance to enhance the neutron imaging capability of small to medium-size neutron sources.

   ↳ physics.ins-detnucl-exphysics.acc-phJINST(2021)·3 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.