Mon·Dec 16, 2019Monday·December 16, 2019

1. 01*

   A Low Energy Rare Event Search with the Majorana Demonstrator

   MAJORANA Collaboration: C. Wiseman · I.J. Arnquist · F.T. Avignone III · A.S. Barabash · C.J. Barton · F.E. Bertrand · B. Bos · M. Busch · M. Buuck · T.S. Caldwell · Y-D. Chan · C.D. Christofferson and 49 other authors

   The MAJORANA DEMONSTRATOR is sensitive to rare events near its energy threshold, including bosonic dark matter, solar axions, and lightly ionizing particles. In this analysis, a novel training set of low energy small-angle Compton scatter events is used to determine the efficiency of pulse shape analysis cuts, and we present updated bosonic dark matter and solar axion results from an 11.17 kg-y dataset using a 5 keV analysis threshold.

   nucl-exastro-ph.COJ.Phys.Conf.Ser.(2020)·11 citations
2. 02*

   Thermonuclear Reaction Rate of ${}^{30}$Si(p,$\gamma$)${}^{31}$P

   John Dermigny · Christian Iliadis🇺🇸 · Art Champagne🇺🇸 · Richard Longland🇺🇸

   Silicon synthesis in high-temperature hydrogen burning environments presents one possible avenue for the study of abundance anomalies in globular clusters. This was suggested in a previous study, which found that the large uncertainties associated with the ${}^{30}$Si(p,$\gamma$)${}^{31}$P reaction rate preclude a firm understanding of the stellar conditions that give rise to the Mg-K anti-correlation observed in the globular cluster NGC 2419. In an effort to improve the reaction rate, we present new strength measurements of the $E_r^{lab}=435$ keV and $E_r^{lab}=501$ keV resonances in ${}^{30}$Si(p,$\gamma$)${}^{31}$P. For the former, which was previously unobserved, we obtain a resonance strength of $\omega \gamma =(1.28\pm 0.25$) $\times 10^{-4}$ eV. For the latter, we obtain a value of $\omega \gamma =(1.88\pm 0.14)$ $\times 10^{-1}$ eV, which has a smaller uncertainty compared to previously measured strengths. Based on these results, the thermonuclear reaction rate has been re-evaluated. The impact of the new measurements is to lower the reaction rate by a factor of $\approx$10 at temperatures important to the study of NGC 2419. The rate uncertainty at these temperatures has also been reduced significantly.

   nucl-exPRC(2020)·8 citations
3. 03*

   Access to decoupled information on Generalized Parton Distributions (GPDs) via Double Deeply Virtual Compton Scattering (DDVCS)

   Shengying Zhao🇫🇷

   The Generalized Parton Distributions (GPDs) constitute an appropriate framework for a universal description of the partonic structure of the nucleon. Double Deeply Virtual Compton Scattering (DDVCS) process provides the only experimental way to measure independently the dependences of the GPDs on the average and transferred momentum. This proceeding discusses the feasibility of a DDVCS experiment in the context of JLab 12 GeV, model-predicted pseudo-data, and extraction of the relevant GPDs information based on a fitter algorithm.

   ↳ hep-phnucl-ex1 citation
4. 04*

   Drawing insights from pion parton distributions

   Minghui Ding🇨🇳 · Khépani Raya🇲🇽 · Daniele Binosi🇮🇹 · Lei Chang🇨🇳 · Craig D. Roberts🇨🇳 · Sebastian M. Schmidt🇩🇪

   A symmetry-preserving continuum approach to the two valence-body bound-state problem is used to calculate the valence, glue and sea distributions within the pion; unifying them with, inter alia, electromagnetic pion elastic and transition form factors. The analysis reveals the following momentum fractions at the scale ${\zeta }_2:=2$GeV: $⟨x_{\mathrm{valence}}⟩=0.48(3)$, $⟨x_{\mathrm{glue}}⟩=0.41(2)$, $⟨x_{\mathrm{sea}}⟩=0.11(2)$; and despite hardening induced by the emergent phenomenon of dynamical chiral symmetry breaking, the valence-quark distribution function, $q^{\pi }(x)$, exhibits the $x\simeq 1$ behaviour predicted by quantum chromodynamics (QCD). After evolution to $\zeta =5.2$GeV, the prediction for $q^{\pi }(x)$ matches that obtained using lattice-regularised QCD. This confluence should both stimulate improved analyses of existing data and aid in planning efforts to obtain new data on the pion distribution functions.

   ↳ hep-phhep-exhep-latnucl-ex+1CPC(2020)·55 citations
5. 05*

   Measuring the skewness dependency of Generalized Parton Distributions

   Shengying Zhao🇫🇷 · Eric Voutier🇫🇷

   Generalized Parton Distributions (GPDs) have emerged over the 1990s as a powerful concept and tool to study nucleon structure. They provide nucleon tomography from the correlation between transverse position and longitudinal momentum of partons. The Double Deeply Virtual Compton Scattering (DDVCS) process consists of the Deeply Virtual Compton Scattering (DVCS) process with a virtual photon in the final state eventually generating a lepton pair, which can be either an electron-positron or a muon-antimuon pair. The virtuality of the final time-like photon can be measured and varied, thus providing an extra lever arm and allowing one to measure the GPDs for the initial and transferred momentum dependences independently. This unique feature of DDVCS is of relevance, among others, for the determination of the distribution of nuclear forces which is accessed through the skewness dependency of GPDs. This proceeding discusses the feasibility and merits of a DDVCS experiment in the context of JLab 12 GeV based on model-predicted pseudo-data and the capability of extraction of Compton Form Factors based on a fitter algorithm.

   ↳ hep-phnucl-exJ.Phys.Conf.Ser.(2020)·2 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.