Tue·May 16, 2017Tuesday·May 16, 2017

1. 01*

   The Beam-Target Helicity Asymmetry for $\vec{\gamma }\vec{n}\to {\pi }^{-}p$ in the {\bf{$N^{\ast }$} Resonance Region

   D. Ho · P. Peng · C. Bass · P. Collins · A. D'Angelo · A. Deur · J. Fleming · C. Hanretty · T. Kageya · M. Khandaker · F.J. Klein · E. Klempt and 131 other authors

   We report the first beam-target double-polarization asymmetries in the $\gamma +n(p)\to {\pi }^{-}+p(p)$ reaction spanning the nucleon resonance region from invariant mass $W$= $1500$ to $2300$ MeV. Circularly polarized photons and longitudinally polarized deuterons in $HD$ have been used with the CLAS detector at Jefferson Lab. The exclusive final state has been extracted using three very different analyses that show excellent agreement, and these have been used to deduce the {\it{E}} polarization observable for an effective neutron target. These results have been incorporated into new partial wave analyses, and have led to significant revisions for several $\gamma n{N}^{\ast }$ resonance photo-couplings.

   nucl-exPRL(2017)·36 citations
2. 02*

   A precision measurement of the e+p/e-p elastic scattering cross section ratio at the OLYMPUS experiment

   Brian S. Henderson🇺🇸

   Measurements of the ratio of the proton elastic form factors (${\mu }_p{G}_E/G_M$) using Rosenbluth separation and those using polarization-based techniques show a strong discrepancy, which has persisted both in modern experimental results and in re-analyses of previous data. The most widely accepted hypothesis to explain this discrepancy is the treatment of the contributions from hard two-photon exchange (TPE) to elastic electron-proton scattering in the radiative corrections applied to the Rosenbluth separation measurements. Calculations of the hard TPE contribution are highly model dependent, but the effect may be measured experimentally with a precise determination of the ratio of the positron-proton and electron-proton elastic scattering cross sections. The OLYMPUS experiment collected approximately 4 fb${}^{-1}$ of \pp and \ep scattering data at the DORIS storage ring at DESY in 2012, with the goal of measuring the elastic \ratio ratio over the kinematic range $(0.4\le ϵ\le 0.9)$, $(0.6\le Q^2\le 2.2)$ GeV${}^2/c^2$ at a fixed lepton beam energy of 2.01 GeV. The detector for the OLYMPUS experiment consisted of refurbished elements of the Bates Large Acceptance Spectrometer Toroid (BLAST) surrounding an internal gaseous hydrogen target, with the addition of multiple systems for the monitoring of the luminosity collected by the experiment. A detailed simulation of the experiment was developed to account for both radiative corrections and various systematic effects. This work presents preliminary results from the OLYMPUS data, demonstrating that the elastic \ratio ratio rises to several percent at $ϵ\approx 0.4$ and indicating a significant contribution from TPE to \pmp scattering. Additionally, the value of \ratio has been measured to unprecedented precision at $ϵ=0.98$, which provides a valuable normalization point for other experimental data.

   nucl-exphysics.ins-det5 citations
3. 03*

   Measuring K${}_{\mathrm{S}}^0$K${}^{\pm }$ interactions using Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV

   ALICE Collaboration

   We present the first ever measurements of femtoscopic correlations between the K${}_{\mathrm{S}}^0$ and K${}^{\pm }$ particles. The analysis was performed on the data from Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV measured by the ALICE experiment. The observed femtoscopic correlations are consistent with final-state interactions proceeding via the $a_0(980)$ resonance. The extracted kaon source radius and correlation strength parameters for K${}_{\mathrm{S}}^0$K${}^{-}$ are found to be equal within the experimental uncertainties to those for K${}_{\mathrm{S}}^0$K${}^{+}$. Comparing the results of the present study with those from published identical-kaon femtoscopic studies by ALICE, mass and coupling parameters for the $a_0$ resonance are constrained. Our results are also compatible with the interpretation of the $a_0$ having a tetraquark structure over that of a diquark.

   nucl-exhep-exPLB(2017)·46 citations
4. 04*

   Observation of Narrow $N^{+}(1685)$ and $N^0(1685)$ Resonances in $\gamma N\to \eta \pi N$ Reactions

   V. Kuznetsov · F. Mammoliti · F. Tortorici · V. Bellini · V. Brio · A. Gridnev · N. Kozlenko · G. Russo · A.Spatafora · M.L.Sperduto · V.Sumachev · C.Sutera

   Observation of a narrow structure at $W\sim 1.68$ GeV in the excitation functions of some photon- and pion-induced reactions may signal a new narrow isospin-1/2 $N(1685)$ resonance. New data on the $\gamma N\to \pi \eta N$ reactions from GRAAL seems to reveal the signals of both $N^{+}(1685)$ and $N^0(1685)$ resonances.

   nucl-exhep-exhep-phnucl-thJETP Lett.(2017)·14 citations
5. 05*

   Measurement of the B+/- meson nuclear modification factor in PbPb collisions at sqrt(s[NN]) = 5.02 TeV

   CMS Collaboration

   The differential production cross sections of B+/- mesons are measured via the exclusive decay channels B+/- to J/psi K+/- to mu+ mu- K+/- as a function of transverse momentum in pp and PbPb collisions at a center-of-mass energy sqrt(s[NN]) = 5.02 TeV per nucleon pair with the CMS detector at the LHC. The pp (PbPb) dataset used for this analysis corresponds to an integrated luminosity of 28.0 inverse picobarns (351 inverse microbarns). The measurement is performed in the B+/- meson transverse momentum range of 7 to 50 GeV/c, in the rapidity interval abs(y) < 2.4. In this kinematic range, a strong suppression of the production cross section by about a factor of two is observed in the PbPb system in comparison to the expectation from pp reference data. These results are found to be roughly compatible with theoretical calculations incorporating beauty quark diffusion and energy loss in a quark-gluon plasma.

   ↳ hep-exnucl-exPRL(2017)·161 citations
6. 06*

   Characterization of a Deuterium-Deuterium Plasma Fusion Neutron Generator

   R.F. Lang🇺🇸 · J. Pienaar🇺🇸 · E. Hogenbirk🇳🇱 · D. Masson🇺🇸 · R. Nolte🇩🇪 · A Zimbal🇩🇪 · S. Röttger🇩🇪 · M. L. Benabderrahmane🇦🇪 · G Bruno🇮🇹

   We characterize the neutron output of a deuterium-deuterium plasma fusion neutron generator, model 35-DD-W-S, manufactured by NSD/Gradel-Fusion. The measured energy spectrum is found to be dominated by neutron peaks at 2.2 MeV and 2.7 MeV. A detailed GEANT4 simulation accurately reproduces the measured energy spectrum and confirms our understanding of the fusion process in this generator. Additionally, a contribution of 14.1 MeV neutrons from deuterium-tritium fusion is found at a level of~$3.5\%$, from tritium produced in previous deuterium-deuterium reactions. We have measured both the absolute neutron flux as well as its relative variation on the operational parameters of the generator. We find the flux to be proportional to voltage $V^{3.32\pm 0.14}$ and current $I^{0.97\pm 0.01}$. Further, we have measured the angular dependence of the neutron emission with respect to the polar angle. We conclude that it is well described by isotropic production of neutrons within the cathode field cage.

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2018)·27 citations
7. 07*

   Interference Effect Between Neutron Direct and Resonance Capture Reactions For Neutron-Rich Nuclei

   Futoshi Minato🇯🇵 · Tokuro Fukui🇯🇵

   Interference effect of neutron capture cross section between the compound and direct processes is investigated. The compound process is calculated by resonance parameters and the direct process by the potential mode. The interference effect is tested for neutron-rich ${}^{82}$Ge and ${}^{134}$Sn nuclei relevant to $r$-process and light nucleus ${}^{13}$C which is neutron poison in the $s$-process and produces long-lived radioactive nucleus ${}^{14}$C ($T_{1/2}=5700$ y). The interference effects in those nuclei are significant around resonances, and low energy region if $s$-wave neutron direct capture is possible. Maxwellian averaged cross sections at $kT=30$ and $300$ keV are also calculated, and the interference effect changes the Maxwellian averaged capture cross section largely depending on resonance position.

   ↳ nucl-thnucl-exEPJ Web Conf.(2017)·1 citation
8. 08*

   Solitonic excitations in collisions of superfluid nuclei: a qualitatively new phenomenon distinct from the Josephson effect

   Kazuyuki Sekizawa🇯🇵 · Gabriel Wlazłowski🇵🇱 · Piotr Magierski🇵🇱

   Recently, we have reported a novel role of pairing in low-energy heavy ion reactions at energies above the Coulomb barrier, which may have a detectable impact on reaction outcomes, such as the kinetic energy of fragments and the fusion cross section [arXiv:1611.10261, arXiv:1702.00069]. The phenomenon mimics the one studied experimentally with ultracold atomic gases, where two clouds of fermionic superfluids with different phases of the pairing fields are forced to merge, inducing various excitation modes of the pairing field. Although it originates from the phase difference of the pairing fields, the physics behind it is markedly different from the so-called Josephson effect. In this short contribution, we will briefly outline the results discussed in our recent papers and explain relations with the field of ultracold atomic gases.

   ↳ nucl-thcond-mat.quant-gascond-mat.supr-connucl-exEPJ Web Conf.(2017)·11 citations
9. 09*

   Configuration mixing in low-lying spectra of carbon hypernuclei

   H. Xia🇨🇳 · H. Mei🇺🇸 · J. M. Yao🇺🇸

   We perform a coupled-channels study of the low-lying states in ${}_{\Lambda }^{13,15,17,19}$C with a covariant energy density functional based microscopic particle-core coupling model. The energy differences of $1/2^{-}$ and $3/2^{-}$ states in ${}_{\Lambda }^{13}$C and ${}_{\Lambda }^{15}$C are predicted to be 0.25 MeV and 0.34 MeV, respectively. We find that configuration mixings in the $1/2^{-}$ and $3/2^{-}$ states of ${}_{\Lambda }^{15}$C are the weakest among those of ${}_{\Lambda }^{13,15,17,19}$C. It indicates that ${}_{\Lambda }^{15}$C provides the best candidate among the carbon hypernuclei to study the spin-orbit splitting of $p_{\Lambda }$ hyperon state.

   ↳ nucl-thnucl-exSCPMA(2017)·10 citations
10. 10*

    Empirical information on nuclear matter fourth-order symmetry energy from an extended nuclear mass formula

    Rui Wang🇨🇳 · Lie-Wen Chen🇨🇳

    We establish a relation between the equation of state (EOS) of nuclear matter and the fourth-order symmetry energy $a_{\mathrm{sym},4}(A)$ of finite nuclei in a semi-empirical nuclear mass formula by self-consistently considering the bulk, surface and Coulomb contributions to the nuclear mass. Such a relation allows us to extract information on nuclear matter fourth-order symmetry energy $E_{\mathrm{sym},4}({\rho }_0)$ at normal nuclear density ${\rho }_0$ from analyzing nuclear mass data. Based on the recent precise extraction of $a_{\mathrm{sym},4}(A)$ via the double difference of the "experimental" symmetry energy extracted from nuclear masses, for the first time, we estimate a value of $E_{\mathrm{sym},4}({\rho }_0)=20.0\pm 4.6$ MeV. Such a value of $E_{\mathrm{sym},4}({\rho }_0)$ is significantly larger than the predictions from mean-field models and thus suggests the importance of considering the effects of beyond the mean-field approximation in nuclear matter calculations.

    ↳ nucl-thastro-ph.SRnucl-exPLB(2017)·20 citations
11. 11*

    The Energy Distribution of Subjets and the Jet Shape

    Zhong-Bo Kang🇺🇸 · Felix Ringer🇺🇸 · Wouter J. Waalewijn🇳🇱

    We present a framework that describes the energy distribution of subjets of radius $r$ within a jet of radius $R$. We consider both an inclusive sample of subjets as well as subjets centered around a predetermined axis, from which the jet shape can be obtained. For $r\ll R$ we factorize the physics at angular scales $r$ and $R$ to resum the logarithms of $r/R$. For central subjets, we consider both the standard jet axis and the winner-take-all axis, which involve double and single logarithms of $r/R$, respectively. All relevant one-loop matching coefficients are given, and an inconsistency in some previous results for cone jets is resolved. Our results for the standard jet shape differ from previous calculations at next-to-leading logarithmic order, because we account for the recoil of the standard jet axis due to soft radiation. Numerical results are presented for an inclusive subjet sample for $pp\to \mathrm{jet}+X$ at next-to-leading order plus leading logarithmic order.

    ↳ hep-phhep-exnucl-exnucl-thJHEP(2017)·74 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.