Fri·Sep 25, 2020Friday·September 25, 2020

1. 01*

   Cross Section Measurements of Deuteron Electro-Disintegration at Very High Recoil Momenta and Large 4-Momentum Transfers ($Q^2$)

   Carlos Yero🇺🇸

   The ${}^2$H$(e,e^{\prime }p)n$ cross sections have been measured at negative 4-momentum transfers of $Q^2=4.5\pm 0.5$ (GeV/c)${}^2$ and $Q^2=3.5\pm 0.5$ (GeV/c)${}^2$ reaching neutron recoil (missing) momenta up to $p_{\mathrm{r}}\sim$1.0 GeV/c. The data have been obtained at fixed neutron recoil angles $5^{\circ }\le {\theta }_{nq}\le 95^{\circ }$ with respect to the 3-momentum transfer $\vec{q}$. The new data agree well with the previous data which reached $p_{\mathrm{r}}\sim 550$ MeV/c. At ${\theta }_{nq}=35^{\circ }$ and $45^{\circ }$, final state interactions (FSI), meson exchange currents (MEC) and isobar configurations (IC) are suppressed and the plane wave impulse approximation (PWIA) provides the dominant cross section contribution. The new data are compared to recent theoretical calculations, and a significant disagreement for recoil momenta $p_{\mathrm{r}}>700$ MeV/c is observed.

   nucl-ex4 citations
2. 02*

   Consistent description of angular correlations in $\beta$ decay for Beyond Standard Model physics searches

   Leendert Hayen🇺🇸 · Albert R. Young🇺🇸

   Measurements of angular correlations between initial and final particles in $\beta$ decay remain one of the most promising ways of probing the Standard Model and looking for new physics. As experiments reach unprecedented precision well into the per-mille regime, proper extraction of results requires one to take into account a great number of nuclear structure and radiative corrections in a procedure which becomes dependent upon the experimental geometry. We provide here a compilation and update of theoretical results which describe all corrections in the same conceptual framework, point out pitfalls and review the influence of the experimental geometry. Finally, we summarize the potential for new physics reach.

   ↳ nucl-thnucl-ex23 citations
3. 03*

   Contact interaction analysis of pion GTMDs

   Jin-Li Zhang🇨🇳 · Zhu-Fang Cui🇨🇳 · Jia-Lun Ping🇨🇳 · Craig D. Roberts🇨🇳

   A contact interaction is used to calculate an array of pion twist-two, -three and -four generalised transverse light-front momentum dependent parton distribution functions (GTMDs). Despite the interaction's simplicity, many of the results are physically relevant, amongst them a statement that GTMD size and shape are largely prescribed by the scale of emergent hadronic mass. Moreover, proceeding from GTMDs to generalised parton distributions (GPDs), it is found that the pion's mass distribution form factor is harder than its electromagnetic form factor, which is harder than the gravitational pressure distribution form factor; the pressure in the neighbourhood of the pion's core is commensurate with that at the centre of a neutron star; the shear pressure is maximal when confinement forces become dominant within the pion; and the spatial distribution of transversely polarised quarks within the pion is asymmetric. Regarding transverse momentum dependent distribution functions (TMDs), their magnitude and domain of support decrease with increasing twist. The simplest Wigner distribution associated with the pion's twist-two dressed-quark GTMD is sharply peaked on the kinematic domain associated with valence-quark dominance; has a domain of negative support; and broadens as the transverse position variable increases in magnitude.

   ↳ hep-phhep-exhep-latnucl-ex+1EPJC(2021)·61 citations
4. 04*

   A Silicon Beam Tracker

   J. H. Han · H. S. Ahn · J. B. Bae · H. J. Hyun · S. W. Jung🇰🇷 · D. H. Kah · C. H. Kim🇺🇸 · H. J. Kim🇰🇷 · K. C. Kim · M. H. Lee🇰🇷 · L. Lutz · A. Malinin🇷🇺 and 8 other authors

   When testing and calibrating particle detectors in a test beam, accurate tracking information independent of the detector being tested is extremely useful during the offline analysis of the data. A general-purpose Silicon Beam Tracker (SBT) was constructed with an active area of 32.0 x 32.0 mm2 to provide this capability for the beam calibration of the Cosmic Ray Energetics And Mass (CREAM) calorimeter. The tracker consists of two modules, each comprised of two orthogonal layers of 380 {\mu}m thick silicon strip sensors. In one module each layer is a 64-channel AC-coupled single-sided silicon strip detector (SSD) with a 0.5 mm pitch. In the other, each layer is a 32-channel DC-coupled single-sided SSD with a 1.0 mm pitch. The signals from the 4 layers are read out using modified CREAM hodoscope front-end electronics with a USB 2.0 interface board to a Linux DAQ PC. In this paper, we present the construction of the SBT, along with its performance in radioactive source tests and in a CERN beam test in October 2006.

   ↳ physics.ins-dethep-exnucl-ex2 citations
5. 05*

   Theoretical Analysis of Antineutron-Nucleus Data needed for Antineutron Mirrors in Neutron-Antineutron Oscillation Experiments

   K.V. Protasov🇫🇷 · V. Gudkov🇺🇸 · E. A. Kupriyanova🇷🇺 · V.V.Nesvizhevsky🇫🇷 · W.M. Snow🇺🇸 · A.Yu. Voronin🇷🇺

   The values of the antineutron-nucleus scattering lengths, and in particular their imaginary parts, are needed to evaluate the feasibility of using neutron mirrors in laboratory experiments to search for neutron-antineutron oscillations. We analyze existing experimental and theoretical constraints on these values with emphasis on low $A$ nuclei and use the results to suggest materials for the neutron/antineutron guide and to evaluate the systematic uncertainties in estimating the neutron-antineutron oscillation time. As an example we discuss a scenario for a future neutron-antineutron oscillation experiment proposed for the European Spallation Source. We also suggest future experiments which can provide a better determination of the values of antineutron-nuclei scattering lengths.

   ↳ hep-phnucl-exnucl-thPRD(2020)·18 citations
6. 06*

   A study on energy resolution of CANDLES detector

   B. T. Khai🇯🇵 · S. Ajimura🇯🇵 · W. M. Chan🇯🇵 · K. Fushimi🇯🇵 · R. Hazama🇯🇵 · H. Hiraoka🇯🇵 · T. Iida🇯🇵 · K. Kanagawa🇯🇵 · H. Kino🇯🇵 · T. Kishimoto🇯🇵 · T. Maeda🇯🇵 · K. Nakajima🇯🇵 and 11 other authors

   In a neutrinoless double-beta decay ($0\nu \beta \beta$) experiment, energy resolution is important to distinguish between $0\nu \beta \beta$ and background events. CAlcium fluoride for studies of Neutrino and Dark matters by Low Energy Spectrometer (CANDLES) discerns the $0\nu \beta \beta$ of ${}^{48}$Ca using a CaF${}_2$ scintillator as the detector and source. Photomultiplier tubes (PMTs) collect scintillation photons. At the Q-value of ${}^{48}$Ca, the current energy resolution (2.6%) exceeds the ideal statistical fluctuation of the number of photoelectrons (1.6%). Because of CaF${}_2$'s long decay constant of 1000 ns, a signal integration within 4000 ns is used to calculate the energy. The baseline fluctuation (${\sigma }_{baseline}$) is accumulated in the signal integration, thus degrading the energy resolution. This paper studies ${\sigma }_{baseline}$ in the CANDLES detector, which severely degrades the resolution by 1% at the Q-value of ${}^{48}$Ca. To avoid ${\sigma }_{\mathrm{baseline}}$, photon counting can be used to obtain the number of photoelectrons in each PMT; however, a significant photoelectron signal overlapping probability in each PMT causes missing photoelectrons in counting and reduces the energy resolution. "Partial photon counting" reduces ${\sigma }_{baseline}$ and minimizes photoelectron loss. We obtain improved energy resolutions of 4.5-4.0% at 1460.8 keV ($\gamma$-ray of ${}^{40}$K), and 3.3-2.9% at 2614.5 keV ($\gamma$-ray of ${}^{208}$Tl). The energy resolution at the Q-value is estimated to be improved from 2.6% to 2.2%, and the detector sensitivity for the $0\nu \beta \beta$ half-life of ${}^{48}$Ca can be improved by 1.09 times.

   ↳ physics.ins-dethep-exnucl-exIEEE Trans.Nucl.Sci.(2021)·1 citation
7. 07*

   Dilepton production in microscopic transport theory with in-medium $\rho$-meson spectral function

   A.B. Larionov🇩🇪 · U. Mosel🇩🇪 · L. von Smekal🇩🇪

   We use the microscopic GiBUU transport model to calculate dilepton ($e^{+}{e}^{-}$) production in heavy-ion collisions at SIS18 energies focusing on the effect of collisional broadening of the $\rho$-meson. The collisional width of the $\rho$-meson at finite temperature and baryon density in nuclear matter is calculated on the basis of the collision integral of the GiBUU model. A systematic comparison with HADES data on dilepton production in heavy-ion collisions is performed. The collisional broadening of the $\rho$ improves the agreement between theory and experiment for the dilepton invariant-mass distributions near the $\rho$ pole mass and for the excess radiation in Au+Au at $1.23A$ GeV. We furthermore show that some remaining underprediction of the experimental dilepton spectra in C+C at $1A$ GeV and Au+Au at $1.23A$ GeV at intermediate invariant masses $0.2-0.4$ GeV can be accounted for by adjusting the $pn$ bremsstrahlung cross section in a way to agree with the inclusive dilepton spectrum from $dp$ collisions at $1.25A$ GeV.

   ↳ nucl-thhep-exhep-phnucl-exPRC(2021)·20 citations
8. 08*

   UPC: a powerful tool for $\mathrm{J}/\psi$ photoproduction analysis in ALICE

   Simone Ragoni (for the ALICE Collaboration)🇬🇧

   Ultra-peripheral collisions (UPC) occur when the interacting nuclei or protons have an impact parameter larger than the sum of their radii. They are mediated by virtual photon exchange. The photoproduction of heavy vector mesons is especially interesting because they couple to the photon. The ALICE Collaboration has analysed both p-Pb and Pb-Pb UPC at the centre-of-mass energy of $\sqrt{s_{\mathrm{NN}}}=5.02$TeV which correspond to $\gamma$p and $\gamma$-Pb interactions, respectively. This poster reports the exclusive photoproduction of $\mathrm{J}/\psi$ off proton and Pb targets, which shed light on the occurrence of saturation and nuclear shadowing, respectively. In more detail, the p-Pb results measure the growth of the cross section for exclusive production over a wide range in Bjorken-$x$ from ~$10^{-2}$ to ~$10^{-5}$, while Pb-Pb results demonstrate the presence of nuclear shadowing at high energies and low scales of the order of the mass of the $\mathrm{J}/\psi$.

   ↳ hep-exnucl-exPoS(2021)·1 citation
9. 09*

   Characterization of Germanium Detectors for the First Underground Laboratory in Mexico

   A. Aguilar-Arevalo🇲🇽 · S. Alvarado-Mijangos🇲🇽 · X. Bertou🇦🇷 · C. Canet🇲🇽 · M. A. Cruz-Pérez🇬🇧 · A. Deisting🇲🇽 · A. Dias · J. C. D'Olivo🇲🇽 · F. Favela-Pérez🇲🇽 · E. A. Garcés · A. González Muñoz🇲🇽 · J. O. Guerra-Pulido🇲🇽 and 12 other authors

   This article reports the characterization of two High Purity Germanium detectors performed by extracting and comparing their efficiencies using experimental data and Monte Carlo simulations. The efficiencies were calculated for pointlike $\gamma$-ray sources as well as for extended calibration sources. Characteristics of the detectors such as energy linearity, energy resolution, and full energy peak efficiencies are reported from measurements performed on surface laboratories. The detectors will be deployed in a $\gamma$-ray assay facility that will be located in the first underground laboratory in Mexico, Laboratorio Subterráneo de Mineral del Chico (LABChico), in the Comarca Minera UNESCO Global Geopark

   ↳ physics.ins-dethep-exnucl-exJINST(2020)·4 citations
10. 10*

    Two-nucleon S-wave interactions at the $SU(3)$ flavor-symmetric point with $m_{ud}\simeq m_s^{\mathrm{phys}}$: a first lattice QCD calculation with the stochastic Laplacian Heaviside method

    Ben Hörz🇺🇸 · Dean Howarth🇺🇸 · Enrico Rinaldi🇯🇵 · Andrew Hanlon🇩🇪 · Chia Cheng Chang🇯🇵 · Christopher Körber🇺🇸 · Evan Berkowitz🇺🇸 · John Bulava🇩🇰 · M.A. Clark🇺🇸 · Wayne Tai Lee🇺🇸 · Colin Morningstar🇺🇸 · Amy Nicholson🇺🇸 · Pavlos Vranas🇺🇸 · André Walker-Loud🇺🇸

    We report on the first application of the stochastic Laplacian Heaviside method for computing multi-particle interactions with lattice QCD to the two-nucleon system. Like the Laplacian Heaviside method, this method allows for the construction of interpolating operators which can be used to construct a positive definite set of two-nucleon correlation functions, unlike nearly all other applications of lattice QCD to two nucleons in the literature. It also allows for a variational analysis in which optimal linear combinations of the interpolating operators are formed that couple predominantly to the eigenstates of the system. Utilizing such methods has become of paramount importance in order to help resolve the discrepancy in the literature on whether two nucleons in either isospin channel form a bound state at pion masses heavier than physical, with the discrepancy persisting even in the $SU(3)$-flavor symmetric point with all quark masses near the physical strange quark mass. This is the first in a series of papers aimed at resolving this discrepancy. In the present work, we employ the stochastic Laplacian Heaviside method without a hexaquark operator in the basis at a lattice spacing of $a\sim 0.086$~fm, lattice volume of $L=48a\simeq 4.1$~fm and pion mass $m_{\pi }\simeq 714$ MeV. With this setup, the observed spectrum of two-nucleon energy levels strongly disfavors the presence of a bound state in either the deuteron or dineutron channel.

    ↳ hep-lathep-phnucl-exnucl-thPRC(2021)·94 citations
11. 11*

    Joint thrust and TMD resummation in electron-positron and electron-proton collisions

    Yiannis Makris🇮🇹 · Felix Ringer🇺🇸 · Wouter J. Waalewijn🇳🇱

    We present the framework for obtaining precise predictions for the transverse momentum of hadrons with respect to the thrust axis in $e^{+}{e}^{-}$ collisions. This will enable a precise extraction of transverse momentum dependent (TMD) fragmentation functions from a recent measurement by the Belle Collaboration. Our analysis takes into account, for the first time, the nontrivial interplay between the hadron transverse momentum and the cut on the thrust event shape. To this end, we identify three different kinematic regions, derive the corresponding factorization theorems within Soft Collinear Effective Theory, and present all ingredients needed for the joint resummation of the transverse momentum and thrust spectrum at NNLL accuracy. One kinematic region can give rise to non-global logarithms (NGLs), and we describe how to include the leading NGLs. We also discuss alternative measurements in $e^{+}{e}^{-}$ collisions that can be used to access the TMD fragmentation function. Finally, by using crossing symmetry, we obtain a new way to constrain TMD parton distributions, by measuring the displacement of the thrust axis in $ep$ collisions.

    ↳ hep-phhep-exnucl-exnucl-thJHEP(2021)·26 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.