Tue·Aug 16, 2016Tuesday·August 16, 2016

1. 01*

   Test of Lorentz invariance in $\beta$ decay of polarized ${}^{20}\text{Na}$

   A. Sytema🇳🇱 · J.E. van den Berg🇳🇱 · O. Böll🇳🇱 · D. Chernowitz · E.A. Dijck🇳🇱 · J.O. Grasdijk · S. Hoekstra🇳🇱 · K. Jungmann🇳🇱 · S.C. Mathavan · C. Meinema🇳🇱 · A. Mohanty🇮🇳 · S.E. Müller🇩🇪 and 8 other authors

   We search for a dependence of the lifetime of ${}^{20}\text{Na}$ nuclei on the nuclear spin direction. Such a directional dependence would be evidence for Lorentz-invariance violation in weak interactions. A difference in lifetime between nuclei that are polarized in the east and west direction is searched for. This difference is maximally sensitive to the rotation of the Earth, while the sidereal dependence is free from most systematic errors. The experiment sets a limit of $2\times 10^{-4}$ at 90 % C.L. on the amplitude of the sidereal variation of the relative lifetime differences, an improvement by a factor 15 compared to an earlier result.

   nucl-exPRC(2016)·7 citations
2. 02*

   Charge-dependent directed flow in Cu+Au collisions at $\sqrt{s_{{}_{NN}}}$ = 200 GeV

   STAR Collaboration: L. Adamczyk · J. K. Adkins · G. Agakishiev · M. M. Aggarwal · Z. Ahammed · I. Alekseev · D. M. Anderson · R. Aoyama · A. Aparin · D. Arkhipkin · E. C. Aschenauer · M. U. Ashraf and 335 other authors

   We present the first measurement of charge-dependent directed flow in Cu+Au collisions at $\sqrt{s_{{}_{NN}}}$ = 200 GeV. The results are presented as a function of the particle transverse momentum and pseudorapidity for different centralities. A finite difference between the directed flow of positive and negative charged particles is observed that qualitatively agrees with the expectations from the effects of the initial strong electric field between two colliding ions with different nuclear charges. The measured difference in directed flow is much smaller than that obtained from the parton-hadron-string-dynamics (PHSD) model, which suggests that most of the electric charges, i.e. quarks and antiquarks, have not yet been created during the lifetime of the strong electric field, which is of the order of, or less than, 1fm/$c$.

   nucl-exPRL(2017)·42 citations
3. 03*

   Coherent pion production in proton-deuteron collisions

   S. Dymov🇷🇺 · V. Shmakova🇷🇺 · D. Mchedlishvili🇬🇪 · T. Azaryan🇷🇺 · S. Barsov🇷🇺 · A. Dzyuba🇷🇺 · R. Engels🇩🇪 · R. Gebel🇩🇪 · P. Goslawski🇩🇪 · B. Gou🇨🇳 · K. Grigoryev🇷🇺 · M. Hartmann🇩🇪 and 27 other authors

   Values of the proton analysing power in the $pd\to {}^3\text{He}{\pi }^0{/}^3\text{H}{\pi }^{+}$ reactions at 350-360~MeV per nucleon were obtained by using a polarised proton beam incident on a deuterium cluster-jet target and with a polarised deuteron beam incident on a target cell filled with polarised hydrogen. These results have a much larger angular coverage than existing data. First measurements are also presented of the deuteron vector analysing power and the deuteron-proton spin correlations. Data were also obtained on the deuteron-proton spin correlation and proton analysing power at small angles at 600~MeV per nucleon, though the angular coverage at this energy was much more restricted even when using a deuteron beam. By combining the extrapolated values of the spin correlations to the forward or backward directions with published measurements of the deuteron tensor analysing powers, the relative phases between the two non-vanishing amplitudes were evaluated.

   nucl-exPLB(2016)·4 citations
4. 04*

   Results of the ASY-EOS experiment at GSI: The symmetry energy at suprasaturation density

   P. Russotto🇮🇹 · S. Gannon🇬🇧 · S. Kupny🇵🇱 · P. Lasko🇵🇱 · L. Acosta🇮🇹 · M. Adamczyk🇵🇱 · A. Al-Ajlan🇸🇦 · M. Al-Garawi🇸🇦 · S. Al-Homaidhi🇸🇦 · F. Amorini🇮🇹 · L. Auditore🇮🇹 · T. Aumann🇩🇪 and 80 other authors

   Directed and elliptic flows of neutrons and light charged particles were measured for the reaction 197Au+197Au at 400 MeV/nucleon incident energy within the ASY-EOS experimental campaign at the GSI laboratory. The detection system consisted of the Large Area Neutron Detector LAND, combined with parts of the CHIMERA multidetector, of the ALADIN Time-of-flight Wall, and of the Washington-University Microball detector. The latter three arrays were used for the event characterization and reaction-plane reconstruction. In addition, an array of triple telescopes, KRATTA, was used for complementary measurements of the isotopic composition and flows of light charged particles. From the comparison of the elliptic flow ratio of neutrons with respect to charged particles with UrQMD predictions, a value \gamma = 0.72 \pm 0.19 is obtained for the power-law coefficient describing the density dependence of the potential part in the parametrization of the symmetry energy. It represents a new and more stringent constraint for the regime of supra-saturation density and confirms, with a considerably smaller uncertainty, the moderately soft to linear density dependence deduced from the earlier FOPI-LAND data. The densities probed are shown to reach beyond twice saturation.

   nucl-exPRC(2016)·267 citations
5. 05*

   Impacts of B-factory measurements on determination of fragmentation functions from electron-positron annihilation data

   M. Hirai🇯🇵 · H. Kawamura🇯🇵 · S. Kumano🇯🇵 · K. Saito🇯🇵

   Fragmentation functions are determined for the pion and kaon by global analyses of charged-hadron production data in electron-positron annihilation. Accurate measurements were reported by the Belle and BaBar collaborations for the fragmentation functions at the center-of-mass energies of 10.52 GeV and 10.54 GeV, respectively, at the KEK and SLAC B factories, whereas other available $e^{+}{e}^{-}$ measurements were mostly done at higher energies, mainly at the $Z$ mass of 91.2 GeV. There is a possibility that gluon fragmentation functions, as well as quark fragmentation functions, are accurately determined by scaling violation. We report our global analysis of the fragmentation functions especially to show impacts of the B-factory measurements on the fragmentation function determination. Our results indicate that the fragmentation functions are determined more accurately not only by the scaling violation but also by high-statistical nature of the Belle and BaBar data. However, there are some tensions between the Belle and BaBar data in comparison with previous measurements. We also explain how the flavor dependence of quark fragmentation functions and the gluon function are separated by using measurements at different $Q^2$ values. In particular, the electric and weak changes are different depending on the quark type, so that a light-quark flavor separation also became possible in principle due to the precise data at both $\sqrt{s}\simeq 10.5$ GeV and 91.2 GeV.

   ↳ hep-phhep-exnucl-exnucl-thPTEP(2016)·23 citations
6. 06*

   Precise Determination of the U-235 Reactor Antineutrino Cross Section per Fission

   Carlo Giunti🇮🇹

   We investigate which among the reactor antineutrino fluxes from the decays of the fission products of ${}^{235}\text{U}$, ${}^{238}\text{U}$, ${}^{239}\text{Pu}$, and ${}^{241}\text{Pu}$ may be responsible for the reactor antineutrino anomaly if the anomaly is due to a miscalculation of the antineutrino fluxes. We find that it is very likely that at least the calculation of the ${}^{235}\text{U}$ flux must be revised. From the fit of the data we obtain the precise determination ${\sigma }_{f,235}=(6.33\pm 0.08)\times 10^{-43}{\text{cm}}^2/\text{fission}$ of the ${}^{235}\text{U}$ cross section per fission, which is more precise than the calculated value and differs from it by $2.2\sigma$. The cross sections per fission of the other fluxes have large uncertainties and in practice their values are undetermined by the fit.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2017)·41 citations
7. 07*

   Probing nuclear effects using single-transverse kinematic imbalance with MINERvA

   X.-G. Lu🇬🇧 · M. Betancourt (for the MINERvA Collaboration)🇺🇸

   Kinematic imbalance of the final-state particles in the plane transverse to the neutrino direction provides a sensitive probe of nuclear effects. In this contribution, we report the MINERvA measurement of the single-transverse kinematic imbalance in neutrino charged-current quasielastic-like events on CH targets. To improve the momentum measurements of the final-state particles, we develop a method to select elastically scattering contained (ESC) protons and a general procedure to correct the transverse momentum scales.

   ↳ hep-exnucl-exJ.Phys.Conf.Ser.(2017)·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.