Mon·Apr 18, 2016Monday·April 18, 2016

1. 01*

   Target and Beam-Target Spin Asymmetries in Exclusive ${\pi }^{+}$ and ${\pi }^{-}$ Electroproduction with 1.6 to 5.7 GeV Electrons

   P.E. Bosted🇺🇸 · A.S. Biselli🇺🇸 · S. Careccia🇺🇸 · G. Dodge🇺🇸 · R. Fersch🇺🇸 · S.E. Kuhn🇺🇸 · J. Pierce🇺🇸 · Y. Prok🇺🇸 · X. Zheng🇺🇸 · K.P. Adhikari🇺🇸 · D. Adikaram🇺🇸 · Z. Akbar🇺🇸 and 150 other authors

   Beam-target double spin asymmetries and target single-spin asymmetries in exclusive ${\pi }^{+}$ and ${\pi }^{-}$ electroproduction were obtained from scattering of 1.6 to 5.7 GeV longitudinally polarized electrons from longitudinally polarized protons (for ${\pi }^{+}$) and deuterons (for ${\pi }^{-}$) using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. The kinematic range covered is $1.1<W<2.6$ GeV and $0.05<Q^2<5$ GeV${}^2$, with good anglular coverage in the forward hemisphere. The asymmetry results were divided into approximately 40,000 kinematic bins for ${\pi }^{+}$ from free protons and 15,000 bins for ${\pi }^{-}$ production from bound nucleons in the deuteron. The present results are found to be in reasonable agreement with fits to previous world data for $W<1.7$ GeV and $Q^2<0.5$ GeV${}^2$, with discrepancies increasing at higher values of $Q^2$, especially for $W>1.5$ GeV. Very large target-spin asymmetries are observed for $W>1.6$ GeV. When combined with cross section measurements, the present results will provide powerful constraints on nucleon resonance amplitudes at moderate and large values of $Q^2$, for resonances with masses as high as 2.3 GeV.

   nucl-exPRC(2016)·9 citations
2. 02*

   Direct determination of the atomic mass difference of Re187 and Os187 for neutrino physics and cosmochronology

   D.A. Nesterenko🇷🇺 · S. Eliseev🇩🇪 · K. Blaum🇩🇪 · M. Block🇩🇪 · S. Chenmarev🇩🇪 · A. Doerr · C. Droese🇩🇪 · P.E. Filianin🇩🇪 · M. Goncharov🇩🇪 · E. Minaya Ramirez🇩🇪 · Yu.N. Novikov🇩🇪 · L. Schweikhard🇩🇪 · V.V. Simon🇩🇪

   For the first time a direct determination of the atomic mass difference of 187Re and 187Os has been performed with the Penning-trap mass spectrometer SHIPTRAP applying the novel phase-imaging ion-cyclotron-resonance technique. The obtained value of 2492(30stat)(15sys) eV is in excellent agreement with the Q values determined indirectly with microcalorimetry and thus resolves a long-standing discrepancy with older proportional counter measurements. This is essential for the determination of the neutrino mass from the beta-decay of 187Re as planned in future microcalorimetric measurements. In addition, an accurate mass difference of 187Re and 187Os is also important for the assessment of 187Re for cosmochronology.

   nucl-exphysics.atom-phphysics.ins-detPRC(2014)·33 citations
3. 03*

   A new study of ${}^{10}$B(p,$\alpha$)${}^7$Be reaction at low energies

   A. Caciolli🇮🇹 · R. Depalo🇮🇹 · C. Broggini🇮🇹 · M. La Cognata🇮🇹 · L. Lamia🇮🇹 · R. Menegazzo🇮🇹 · L. Mou · S. M. R. Puglia🇮🇹 · V. Rigato🇮🇹 · S. Romano🇮🇹 · C. Rossi Alvarez · M. L. Sergi · C. Spitaleri🇮🇹 · A. Tumino🇮🇹

   The ${}^{10}$B(p,$\alpha$)${}^7$Be reaction is of great interest since it has many applications in different fields of research such as nuclear astrophysics, nuclear physics, and models of new reactors for clean energy generation. This reaction has been studied at the AN2000 accelerator of the INFN National Laboratories of Legnaro (LNL). The total cross section has been measured in a wide energy range (250 $-$ 1182 keV) by using the activation method. The decays of the ${}^7$Be nuclei produced by the reaction were measured at the low counting facility of LNL by using two fully shielded high-purity germanium detectors. The present dataset shows a large discrepancy with respect to one of the previous data at the same energies and reduces the total uncertainty to the level of 6\%. An R-matrix calculation has been performed on the present data using the parameters from previous Trojan Horse measurements for the 10 and 500 keV resonances. The present data do not lay on the R-matrix fit in one point suggesting the existence of a ${}^{11}$C level not observed yet. Further nuclear investigations are needed to confirm this hypothesis.

   nucl-exEPJA(2016)·19 citations
4. 04*

   Probing Transverse Momentum Broadening in Heavy Ion Collisions

   A.H. Mueller🇺🇸 · Bin Wu🇫🇷 · Bo-Wen Xiao🇨🇳 · Feng Yuan🇺🇸

   We study the dijet azimuthal de-correlation in relativistic heavy ion collisions as an important probe of the transverse momentum broadening effects of a high energy jet traversing the quark-gluon plasma. We take into account both the soft gluon radiation in vacuum associated with the Sudakov logarithms and the jet P_T-broadening effects in the QCD medium. We find that the Sudakov effects are dominant at the LHC, while the medium effects can play an important role at RHIC energies. This explains why the LHC experiments have not yet observed sizable P_T-broadening effects in the measurement of dijet azimuthal correlations in heavy ion collisions. Future investigations at RHIC will provide a unique opportunity to study the P_T-broadening effects and help to pin down the underlying mechanism for jet energy loss in a hot and dense medium.

   ↳ hep-phnucl-exnucl-thPLB(2016)·75 citations
5. 05*

   $\varphi$-meson production at forward/backward rapidity in high-energy nuclear collisions from a multiphase transport model

   Y. J. Ye🇨🇳 · J. H. Chen🇨🇳 · Y. G. Ma🇨🇳 · S. Zhang🇨🇳 · C. Zhong🇨🇳

   Within the framework of a multiphase transport model (AMPT), the $\varphi$-meson production is studied in d+Au collisions at \srt = {200} GeV in the forward (d-going, $1.2<y<2.2$) and backward (Au-going, $-2.2<y<-1.2$) direction. The AMPT model with string melting version (parton cascade turning-on) describes the experimental data well, while the pure hadronic transport scenario of the AMPT model underestimates the $\varphi$-meson production rate in comparison with the data. Detailed investigations including the rapidity, transverse momentum and collision system size dependencies of $\varphi$-meson nuclear modification factor indicate that a combination of the initial state effect and a follow-up parton cascade is required in the AMPT model to describe the data. Similar calculations are also present in p+Pb collisions at \srt = {5.02} TeV and p+p collisions at \srt = {2.76} TeV. The findings from a comparison of AMPT model study with the data are consistent with that at RHIC energy.

   ↳ nucl-thhep-phnucl-exPRC(2016)·4 citations
6. 06*

   On the possibility of generating a 4-neutron resonance with a {\boldmath $T=3/2$} isospin 3-neutron force

   E. Hiyama🇯🇵 · R. Lazauskas🇫🇷 · J. Carbonell🇫🇷 · M. Kamimura🇯🇵

   We consider the theoretical possibility to generate a narrow resonance in the four neutron system as suggested by a recent experimental result. To that end, a phenomenological $T=3/2$ three neutron force is introduced, in addition to a realistic $NN$ interaction. We inquire what should be the strength of the $3n$ force in order to generate such a resonance. The reliability of the three-neutron force in the $T=3/2$ channel is exmined, by analyzing its consistency with the low-lying $T=1$ states of ${}^4$H, ${}^4$He and ${}^4$Li and the ${}^3\mathrm{H}+n$ scattering. The {\it ab initio} solution of the $4n$ Schrödinger equation is obtained using the complex scaling method with boundary conditions appropiate to the four-body resonances. We find that in order to generate narrow $4n$ resonant states a remarkably attractive $3N$ force in the $T=3/2$ channel is required.

   ↳ nucl-thnucl-exPRC(2016)·86 citations
7. 07*

   Correction methods for finite-acceptance effects in two-particle correlation analyses

   Saehanseul Oh🇺🇸 · Tim Schuster🇺🇸 · Andreas Morsch🇨🇭 · Constantin Loizides🇺🇸

   Two-particle angular correlations have been widely used as a tool to explore particle production mechanisms in heavy-ion collisions. The mixed-event technique is generally used as a standard method to correct for finite-acceptance effects. We demonstrate that event mixing only provides an approximate acceptance correction, and propose new methods for finite-acceptance corrections. Starting from discussions about 2-dimensional correction procedures, new methods are derived for specific assumptions on the properties of the signal, such as uniform signal distribution or $\delta$-function-like trigger particle distribution, and suitable for two-particle correlation analyses from particles at mid-rapidity and jet-hadron or high $p_{\text{T}}$-triggered hadron-hadron correlations. Per-trigger associated particle yields from the mixed-event method and the new methods are compared through Monte Carlo simulations containing well-defined correlation signals. Significant differences are observed at large pseudorapidity differences in general and especially for asymmetric particle distribution like that produced in proton--nucleus collisions. The applicability and validity of the new methods are discussed in detail.

   ↳ nucl-thnucl-exEur.Phys.J.Plus(2016)·5 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.