Mon·Aug 28, 2017Monday·August 28, 2017

1. 01*

   Spectroscopy of pionic atoms in ${}^{122}\text{S}\mathbf{n}(\text{d},{}^3\text{H}\mathbf{e})$ reaction and angular dependence of the formation cross sections

   T. Nishi🇯🇵 · K. Itahashi🇯🇵 · G.P.A. Berg🇺🇸 · H. Fujioka🇯🇵 · N. Fukuda🇯🇵 · N. Fukunishi🇯🇵 · H. Geissel🇩🇪 · R.S. Hayano🇯🇵 · S. Hirenzaki🇯🇵 · K. Ichikawa🇯🇵 · N. Ikeno🇯🇵 · N. Inabe🇯🇵 and 27 other authors

   We observed the atomic $1s$ and $2p$ states of ${\pi }^{-}$ bound to ${}^{121}\mathrm{Sn}$ nuclei as distinct peak structures in the missing mass spectra of the ${}^{122}\mathrm{Sn}(d,{}^3\mathrm{He})$ nuclear reaction. A very intense deuteron beam and a spectrometer with a large angular acceptance let us achieve potential of discovery, which includes capability of determining the angle-dependent cross sections with high statistics. The $2p$ state in a Sn nucleus was observed for the first time. The binding energies and widths of the pionic states are determined and found to be consistent with previous experimental results of other Sn isotopes. The spectrum is measured at finite reaction angles for the first time. The formation cross sections at the reaction angles between 0 and $2^{\circ }$ are determined. The observed reaction-angle dependence of each state is reproduced by theoretical calculations. However, the quantitative comparison with our high-precision data reveals a significant discrepancy between the measured and calculated formation cross sections of the pionic $1s$ state.

   nucl-exPRL(2018)·23 citations
2. 02*

   Halo-induced large enhancement of soft dipole excitation of 11Li observed via proton inelastic scattering

   Junki Tanaka

   Proton inelastic scattering off a neutron halo nucleus, 11Li, has been studied in inverse kinematics at the IRIS facility at TRIUMF. The aim was to establish a soft dipole resonance and to obtain its dipole strength. Using a high quality 66 MeV 11Li beam, a strongly populated excited state in 11Li was observed at Ex=0.80 +/- 0.02 MeV with a width of 1.15 +/- 0.06 MeV. A DWBA (distorted-wave Born approximation) analysis of the measured differential cross section with isoscalar macroscopic form factors leads to conclude that this observed state is excited in an electric dipole (E1) transition. Under the assumption of isoscalar E1 transition, the strength is evaluated to be extremely large amounting to 600 to 2000 Weisskopf units, exhausting 4% to 14% of the isoscalar E1 energy-weighted sum rule (EWSR) value. The large observed strength originates from the halo and is consistent with the simple di-neutron model of 11Li halo.

   nucl-exPLB(2017)·37 citations
3. 03*

   The g2p Experiment: A Measurement of the Proton's Spin Structure Functions

   Ryan Zielinski🇺🇸

   The E08-027 (g2p) experiment measured the spin structure functions of the proton at Jefferson Laboratory in Newport News, Va. Longitudinally polarized electrons were scattered from a transversely and longitudinally polarized solid ammonia target in Hall A, with the polarized NH${}_3$ acting as an effective proton target. Focusing on small scattering angle events at the electron energies available at Jefferson Lab, the experiment covered a kinematic phase space of 0.02 GeV${}^2$ $<Q^2<$ 0.20 GeV${}^2$ in the proton's resonance region. The spin structure functions, $g_1^p(x,Q^2)$ and $g_2^p(x,Q^2)$ , are extracted from an inclusive polarized cross section measurement of the electron-proton interaction. Integrated moments of $g_1(x,Q^2)$ are calculated and compared to theoretical predictions made by Chiral Perturbation Theory. The $g_1(x,Q^2)$ results are in agreement with previous measurements, but include a significant increase in statistical precision. The spin structure function contributions to the hyperfine energy levels in the hydrogen atom are also investigated. The $g_2(x,Q^2)$ measured contribution to the hyperfine splitting is the first ever experimental determination of this quantity. The results of this thesis suggest a disagreement of over 100% with previously published model results.

   nucl-ex4 citations
4. 04*

   Double, triple, and $n$-parton scatterings in high-energy proton and nuclear collisions

   David d'Enterria🇨🇭 · Alexander Snigirev🇷🇺

   The framework to compute the cross sections for the production of particles with high mass and/or large transverse momentum in double- (DPS), triple- (TPS), and in general $n$-parton scatterings, from the corresponding single-parton (${\sigma }_{\mathrm{SPS}}$) values in high-energy proton-proton, proton-nucleus, and nucleus-nucleus is reviewed. The basic parameter of the factorized $n$-parton scattering ansatz is an effective cross section ${\sigma }_{\mathrm{eff}}$ encoding all unknowns about the underlying generalized $n$-parton distribution in the proton (nucleon). In its simplest and most economical form, the ${\sigma }_{\mathrm{eff}}$ parameter can be derived from the transverse parton profile of the colliding protons and/or nucleus, using a Glauber approach. Numerical examples for the cross sections and yields expected for the concurrent DPS or TPS production of heavy-quarks, quarkonia, and/or gauge bosons in proton and nuclear collisions at LHC and Future Circular Collider (FCC) energies are provided. The obtained cross sections are based on perturbative QCD predictions for ${\sigma }_{\mathrm{SPS}}$ at next-to-leading-order (NLO) or next-to-NLO (NNLO) accuracy including, when needed, nuclear modifications of the corresponding parton densities.

   ↳ hep-phastro-ph.HEhep-exnucl-ex+1Adv.Ser.Direct.High Energy Phys.(2018)·54 citations
5. 05*

   Elastic scattering of a quark from a color field: longitudinal momentum exchange

   Jamal Jalilian-Marian🇺🇸

   Perturbative QCD in the small Bjorken $x$ limit can be formulated as an effective theory known as the Color Glass Condensate (CGC) formalism. The CGC formalism takes into account the dynamics of large gluon densities at small $x$ and has been successfully applied to Deep Inelastic Scattering (DIS) and particle production in high energy hadronic and nuclear collisions in the small $x$ kinematic region. The effective degrees of of freedom in CGC are Wilson lines which enter in the effective quark (and gluon) propagators and re-sum multiple soft scatterings from the small $x$ gluon field of the target. It is however known that the CGC effective theory breaks down when one probes the moderately large $x$ (high $p_t$) kinematics where collinear factorization and DGLAP evolution of parton distribution functions should be the right framework. Here we propose a general framework which may allow one to eventually unify the two approaches and to calculate pQCD cross sections in both small and large Bjorken $x$ regions. We take the first step towards this goal by deriving an expression for the quark propagator in a background field which includes scatterings from both small and large $x$ modes of the gluon field of the target. We describe how this quark propagator can be used to calculate QCD structure functions $F_2$ and $F_L$ at all $x$ and thus generalize the dipole model of DIS. We outline this approach can also be used to extend the so-called hybrid approach to particle production in the forward rapidity region of high energy hadronic and nuclear collisions to all $x$ and $p_t$ regions and speculate on how one may apply the same techniques to extend the McLerran-Venugopalan effective action used in high energy heavy ion collisions to include high $p_t$ physics.

   ↳ hep-phnucl-exnucl-thPRD(2017)·47 citations
6. 06*

   The Status and Initial Results of the MAJORANA DEMONSTRATOR Experiment

   V.E. Guiseppe🇺🇸 · N. Abgrall🇺🇸 · S.I. Alvis🇺🇸 · I.J. Arnquist🇺🇸 · F.T. Avignone III🇺🇸 · A.S. Barabash🇷🇺 · C.J. Barton🇺🇸 · F.E. Bertrand🇺🇸 · T. Bode🇩🇪 · A.W. Bradley🇺🇸 · V. Brudanin🇷🇺 · M. Busch🇺🇸 and 58 other authors

   Neutrinoless double-beta decay searches play a major role in determining the nature of neutrinos, the existence of a lepton violating process, and the effective Majorana neutrino mass. The MAJORANA Collaboration assembled an array of high purity Ge detectors to search for neutrinoless double-beta decay in Ge-76. The MAJORANA DEMONSTRATOR is comprised of 44.1 kg (29.7 kg enriched in Ge-76) of Ge detectors divided between two modules contained in a low-background shield at the Sanford Underground Research Facility in Lead, South Dakota, USA. The initial goals of the DEMONSTRATOR are to establish the required background and scalability of a Ge-based next-generation ton-scale experiment. Following a commissioning run that started in 2015, the first detector module started low-background data production in early 2016. The second detector module was added in August 2016 to begin operation of the entire array. We discuss results of the initial physics runs, as well as the status and physics reach of the full MAJORANA DEMONSTRATOR experiment.

   ↳ physics.ins-detnucl-exAIP Conf.Proc.(2017)·9 citations
7. 07*

   $\eta$-nucleus interaction from the $d+d$ reaction around the $\eta$ production threshold

   N. Ikeno🇯🇵 · H. Nagahiro🇯🇵 · D. Jido🇯🇵 · S. Hirenzaki🇯🇵

   The $\eta$ mesic nucleus is considered to be one of the interesting exotic many body systems and has been studied since 1980's theoretically and experimentally. Recently, the formation of the $\eta$ mesic nucleus in the fusion reactions of the light nuclei such as $d+d\to (\eta +\alpha )\to X$ has been proposed and the experiments have been performed by WASA-at-COSY. We develop a theoretical model to evaluate the formation rate of the $\eta$ mesic nucleus in the fusion reactions and show the calculated results. We find that the $\eta$ bound states could be observed in the reactions in cases with the strong attractive and small absorptive $\eta$-nucleus interactions. We compare our results with existing data of the $d+d\to \eta +\alpha$ and the $d+d\to {}^3\mathrm{He}+N+\pi$ reactions. We find that the analyses by our theoretical model with the existing data can provide new information on the $\eta$-nucleus interaction.

   ↳ nucl-thhep-phnucl-exEPJA(2017)·23 citations
8. 08*

   Low Energy Analysis Techniques for CUORE

   CUORE Collaboration: C. Alduino🇺🇸 · K. Alfonso🇺🇸 · D. R. Artusa🇺🇸 · F. T. Avignone III🇺🇸 · O. Azzolini🇮🇹 · G. Bari🇮🇹 · J.W. Beeman🇺🇸 · F. Bellini🇮🇹 · G. Benato🇺🇸 · A. Bersani🇮🇹 · M. Biassoni🇮🇹 · A. Branca🇮🇹 and 111 other authors

   CUORE is a tonne-scale cryogenic detector operating at the Laboratori Nazionali del Gran Sasso (LNGS) that uses tellurium dioxide bolometers to search for neutrinoless double-beta decay of ${}^{130}$Te. CUORE is also suitable to search for low energy rare events such as solar axions or WIMP scattering, thanks to its ultra-low background and large target mass. However, to conduct such sensitive searches requires improving the energy threshold to 10 keV. In this paper, we describe the analysis techniques developed for the low energy analysis of CUORE-like detectors, using the data acquired from November 2013 to March 2015 by CUORE-0, a single-tower prototype designed to validate the assembly procedure and new cleaning techniques of CUORE. We explain the energy threshold optimization, continuous monitoring of the trigger efficiency, data and event selection, and energy calibration at low energies in detail. We also present the low energy background spectrum of CUORE-0 below 60keV. Finally, we report the sensitivity of CUORE to WIMP annual modulation using the CUORE-0 energy threshold and background, as well as an estimate of the uncertainty on the nuclear quenching factor from nuclear recoils in CUORE-0.

   ↳ physics.ins-detnucl-exEPJC(2017)·24 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.