Fri·Aug 4, 2017Friday·August 4, 2017

1. 01*

   Partonic Structure of Light Nuclei

   Whitney Armstrong (1)🇺🇸 · John Arrington (1)🇺🇸 · Ian Cloet (1)🇺🇸 · Kawtar Hafidi (1)🇺🇸 · Mohammad Hattawy (1)🇺🇸 · David Potteveld (1)🇺🇸 · Paul Reimer (1)🇺🇸 · Seamus Riordan (1)🇺🇸 · Z. Yi (1)🇺🇸 · Jacques Ball (2)🇫🇷 · Maxime Defurne (2)🇫🇷 · Michel Garcon (2)🇫🇷 and 36 other authors

   We propose to study the partonic structure of ${}^4$He by measuring the Beam Spin Asymmetry (BSA) in coherent Deeply Virtual Compton Scattering (DVCS) and the differential cross-section of the Deeply Virtual Meson Production (DVMP) of the $\varphi$. Despite its simple structure, a light nucleus such as ${}^4$He has a density and a binding energy comparable to that of heavier nuclei. Therefore, by studying ${}^4$He nucleus, one can learn typical features of the partonic structure of atomic nuclei. The combination of CLAS12 and the ALERT detector provides a unique opportunity to study both the quark and gluon structure of a dense light nucleus. Coherent exclusive DVCS off ${}^4$He will probe the transverse spatial distribution of quarks in the nucleus as a function of the quarks' longitudinal momentum fraction, $x$. In parallel, the average spatial transverse gluon density of the ${}^4$He nucleus will be extracted within a GPD framework using the measured longitudinal cross-section for coherent $\varphi$ production in a similar range of $x$. Additionally, threshold effects of $\varphi$ production can be explored by exploiting the ALERT detector's large acceptance for low $|t|$ events.

   nucl-ex32 citations
2. 02*

   Tagged EMC Measurements on Light Nuclei

   Whitney Armstrong (1) · John Arrington (1) · Ian Cloet (1) · Kawtar Hafidi (1) · Mohammad Hattawy (1) · David Potteveld (1) · Paul Reimer (1) · Seamus Riordan (1) · Z. Yi (1) · Jacques Ball (2) · Maxime Defurne (2) · Michel Garcon (2) and 41 other authors

   We propose to measure tagged deep inelastic scattering from light nuclei (deuterium and ${}^4$He) by detecting the low energy nuclear spectator recoil (p, ${}^3$H and ${}^3$He) in addition to the scattered electron. The proposed experiment will provide stringent tests leading to clear differentiation between the many models describing the EMC effect, by accessing the bound nucleon virtuality through its initial momentum at the point of interaction. Indeed, conventional nuclear physics explanations of the EMC effect mainly based on Fermi motion and binding effects yield very different predictions than more exotic scenarios, where bound nucleons basically loose their identity when embedded in the nuclear medium. By distinguishing events where the interacting nucleon was slow, as described by a mean field scenario, or fast, very likely belonging to a correlated pair, will clearly indicate which phenomenon is relevant to explain the EMC effect. An important challenge for such measurements using nuclear spectators is the control of the theoretical framework and, in particular, final state interactions. This experiment will directly provide the necessary data needed to test our understanding of spectator tagging and final state interactions in ${}^2$H and ${}^4$He and their impact on the semi-inclusive measurements of the EMC effect described above.

   nucl-ex12 citations
3. 03*

   Solar Neutrinos as Background to Neutrinoless Double-beta Decay Experiments

   S.R. Elliott🇺🇸 · H. Ejiri🇯🇵

   Solar neutrinos interact within double-beta decay (\BB) detectors and contribute to backgrounds for \BB\ experiments. Background contributions due to charge-current solar neutrino interactions with \BB\ nuclei of ${}^{76}$Ge, ${}^{82}$Se, ${}^{100}$Mo, ${}^{130}$Te, ${}^{136}$Xe, and ${}^{150}$Nd are evaluated. They are shown to be significant for future high-sensitivity \BB\ experiments that may search for Majorana neutrino masses in the inverted-hierarchy mass region. The impact of solar neutrino backgrounds and their reduction are discussed for future \BB\ experiments.

   nucl-exphysics.ins-detAIP Conf.Proc.(2017)·8 citations
4. 04*

   Coarse graining the Bethe-Goldstone equation: nucleon-nucleon high momentum components

   I. Ruiz Simo🇪🇸 · R. Navarro Perez🇺🇸 · J.E. Amaro🇪🇸 · E. Ruiz Arriola🇪🇸

   The delta-shell representation of the nuclear force allows a simplified treatment of nuclear correlations. We show how this applies to the Bethe-Goldstone equation as an integral equation in coordinate space with a few mesh points, which is solved by inversion of a 5-dimensional square matrix in the single channel cases and a $10\times 10$ matrix for the tensor-coupled channels. This allows us to readily obtain the high momentum distribution, for all partial waves, of a back-to-back correlated nucleon pair in nuclear matter. We find that the probability of finding a high-momentum correlated neutron-proton pair is about 18 times that of a proton-proton one, as a result of the strong tensor force, thus confirming in an independent way previous results and measurements.

   ↳ nucl-thnucl-exPRC(2017)·7 citations
5. 05*

   Neutron matter within QCD sum rules

   Bao-Jun Cai🇨🇳 · Lie-Wen Chen🇨🇳

   Equation of state (EOS) of pure neutron matter (PNM) is studied in QCD sum rules (QCDSR). It is found that the QCDSR results on EOS of PNM are in good agreement with predictions by current advanced microscopic many-body theories. Moreover, the higher-order density terms in quark condensates are shown to be important to describe the empirical EOS of PNM in the density region around and above nuclear saturation density although they play minor role at subsaturation densities. The chiral condensates in PNM are also studied, and our results indicate that the higher-order density terms in quark condensates, which are introduced to reasonably describe the empirical EOS of PNM at suprasaturation densities, tend to hinder the appearance of chiral symmetry restoration in PNM at high densities.

   ↳ nucl-thhep-phnucl-exPRC(2018)·5 citations
6. 06*

   Hard photoproduction of a diphoton with a large invariant mass

   A. Pedrak🇵🇱 · B. Pire🇫🇷 · L. Szymanowski🇵🇱 · J. Wagner🇵🇱

   The electromagnetic probe has proven to be a very efficient way to access the $3-$dimensional structure of the nucleon, particularly thanks to the exclusive Compton processes. We explore the hard photoproduction of a large invariant mass diphoton in the kinematical regime where the diphoton is nearly forward and its invariant mass is the hard scale enabling to factorize the scattering amplitude in terms of generalized parton distributions. This amplitude has a very peculiar and interesting analytic structure. We calculate unpolarized cross sections and the angular asymmetry triggered by a linearly polarized photon beam.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2017)·62 citations
7. 07*

   Reactor Fuel Fraction Information on the Antineutrino Anomaly

   C. Giunti🇮🇹 · X.P. Ji🇨🇳 · M. Laveder🇮🇹 · Y.F. Li🇨🇳 · B.R. Littlejohn🇺🇸

   We analyzed the evolution data of the Daya Bay reactor neutrino experiment in terms of short-baseline active-sterile neutrino oscillations taking into account the theoretical uncertainties of the reactor antineutrino fluxes. We found that oscillations are disfavored at $2.6\sigma$ with respect to a suppression of the ${}^{235}\text{U}$ reactor antineutrino flux and at $2.5\sigma$ with respect to variations of the ${}^{235}\text{U}$ and ${}^{239}\text{Pu}$ fluxes. On the other hand, the analysis of the rates of the short-baseline reactor neutrino experiments favor active-sterile neutrino oscillations and disfavor the suppression of the ${}^{235}\text{U}$ flux at $3.1\sigma$ and variations of the ${}^{235}\text{U}$ and ${}^{239}\text{Pu}$ fluxes at $2.8\sigma$. We also found that both the Daya Bay evolution data and the global rate data are well-fitted with composite hypotheses including variations of the ${}^{235}\text{U}$ or ${}^{239}\text{Pu}$ fluxes in addition to active-sterile neutrino oscillations. A combined analysis of the Daya Bay evolution data and the global rate data shows a slight preference for oscillations with respect to variations of the ${}^{235}\text{U}$ and ${}^{239}\text{Pu}$ fluxes. However, the best fits of the combined data are given by the composite models, with a preference for the model with an enhancement of the ${}^{239}\text{Pu}$ flux and relatively large oscillations.

   ↳ hep-phhep-exnucl-exnucl-thJHEP(2017)·58 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.