Wed·Oct 18, 2017Wednesday·October 18, 2017

1. 01*

   Transverse Momentum and Multiplicity Fluctuations in Ar+Sc Collisions at the CERN SPS from NA61/SHINE

   Evgeny Andronov (for the NA61/SHINE Collaboration)🇷🇺

   The NA61/SHINE experiment aims to discover the critical point of strongly interacting matter and study the properties of the onset of deconfinement. For these goals a scan of the two dimensional phase diagram ($T$-${\mu }_B$) is being performed at the SPS by measurements of hadron production in proton-proton, proton-nucleus and nucleus-nucleus interactions as a function of collision energy and system size. In this contribution preliminary results on transverse momentum and multiplicity fluctuations expressed in terms of strongly intensive quantities from the Ar+Sc energy scan will be presented. These fluctuations are expected to be sensitive to the existence of a critical point. The results are compared with results from the p+p and Be+Be energy scan as well as with NA49 measurements.

   nucl-exActa Phys.Polon.Supp.(2017)·12 citations
2. 02*

   Spectroscopy of ${}^{50}$Sc and ab initio calculations of $B(M3)$ strengths

   A. B. Garnsworthy🇨🇦 · M. Bowry🇨🇦 · B. Olaizola🇨🇦 · J. D. Holt🇨🇦 · S. R. Stroberg🇨🇦 · S. Cruz🇨🇦 · S. Georges🇨🇦 · G. Hackman🇨🇦 · A. D. MacLean🇨🇦 · J. Measures🇨🇦 · H. P. Patel🇨🇦 · C. J. Pearson🇨🇦 · C. E. Svensson🇨🇦

   The GRIFFIN spectrometer at TRIUMF-ISAC has been used to study excited states and transitions in ${}^{50}$Sc following the $\beta$-decay of ${}^{50}$Ca. Branching ratios were determined from the measured $\gamma$-ray intensities, and angular correlations of $\gamma$ rays have been used to firmly assign the spins of excited states. The presence of an isomeric state that decays by an $M3$ transition with a $B(M3)$ strength of 13.6(7)\,W.u. has been confirmed. We compare with the first {\it ab initio} calculations of $B(M3$) strengths in light and medium-mass nuclei from the valence-space in-medium similarity renormalization group approach, using consistently derived effective Hamiltonians and $M3$ operator. The experimental data are well reproduced for isoscalar $M3$ transitions when using bare $g$-factors, but the strength of isovector $M3$ transitions are found to be underestimated by an order of magnitude.

   nucl-exPRC(2017)·10 citations
3. 03*

   Study of the Q.Q Interaction- Single Particle Behavior to Elliott's Rotations

   Arun Kingan · Xiaofei Yu · Larry Zamick🇺🇸

   We perform shell model calculations using a quadrupole-quadrupole interaction (Q.Q).We show results in single j shell spaces and the full S-D shell . We show that one gets useful results with Q.Q in both spaces.. We emphasize the importance of the choice of single particle energies in order to obtain the results of Elliott using a Q.Q interaction without the momentum terms. We show a J(J+1) spectrum for a ground state band but with B(E2)'s different from the rotational model. We also show excited J(J-1), J((J-1) and J(J+3) spectra.We find spectra starting with J=0 which have both even J and odd J members.

   ↳ nucl-thnucl-exquant-phIJMPE(2018)·2 citations
4. 04*

   Thermal dileptons as QCD matter probes at SIS

   Florian Seck🇩🇪 · Tetyana Galatyuk🇩🇪 · Ralf Rapp🇺🇸 · Joachim Stroth🇩🇪

   Electromagnetic radiation is emitted during the whole course of a heavy-ion collision and can escape from the collision zone without further interactions. This makes it an ideal tool to study the properties of hot and dense QCD matter. To model the space-time evolution of the collision at SIS energies a coarse-graining approach is used to convert transport simulations into meaningful temperatures and densities. These parameters serve as input for the determination of the pertinent radiation of thermal dileptons based on an in-medium $\rho$ spectral function that describes available spectra at ultrarelativistic collision energies. The resulting excitation function of the thermal excess radiation provides a baseline for future measurements by the HADES and CBM experiments at GSI/FAIR, and experiments proposed at NICA and J-PARC.

   ↳ nucl-thnucl-exJ.Phys.Conf.Ser.(2018)·4 citations
5. 05*

   Revised neutrino-gallium cross section and prospects of BEST in resolving the Gallium anomaly

   Vladislav Barinov🇷🇺 · Bruce Cleveland🇨🇦 · Vladimir Gavrin🇷🇺 · Dmitry Gorbunov🇷🇺 · Tatiana Ibragimova🇷🇺

   O(1) eV sterile neutrino can be responsible for a number of anomalous results of neutrino oscillation experiments. This hypothesis may be tested at short base-line neutrino oscillation experiments, several of which are either ongoing or under construction. Here we concentrate on the so-called Gallium anomaly, found by SAGE and GALLEX experiments, and its foreseeable future tests with BEST experiment at Baksan Neutrino Observatory. We start with a revision of the neutrino-gallium cross section, that is performed by utilizing the recent measurements of the nuclear final state spectra. We accordingly correct the parameters of Gallium anomaly and refine the BEST prospects in testing it and searching for sterile neutrinos. We further evolve the previously proposed idea to investigate the anomaly with Zn-65 artificial neutrino source as a next option available at BEST, and estimate its sensitivity to the sterile neutrino model parameters following the Bayesian approach. We show that after the two stages of operation BEST will make 5$\sigma$-discovery of the sterile neutrinos, if they are behind the Gallium anomaly.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2018)·41 citations
6. 06*

   Nucleon form factors in dispersively improved Chiral Effective Field Theory II: Electromagnetic form factors

   J. M. Alarcón🇺🇸 · C. Weiss🇺🇸

   We study the nucleon electromagnetic form factors (EM FFs) using a recently developed method combining Chiral Effective Field Theory ($\chi$EFT) and dispersion analysis. The spectral functions on the two-pion cut at $t>4M_{\pi }^2$ are constructed using the elastic unitarity relation and an $N/D$ representation. $\chi$EFT is used to calculate the real functions $J_{\pm }^1(t)=f_{\pm }^1(t)/F_{\pi }(t)$ (ratios of the complex $\pi \pi \to N\bar{N}$ partial-wave amplitudes and the timelike pion FF), which are free of $\pi \pi$ rescattering. Rescattering effects are included through the empirical timelike pion FF $|F_{\pi }(t){|}^2$. The method allows us to compute the isovector EM spectral functions up to $t\sim 1$ GeV${}^2$ with controlled accuracy (LO, NLO, and partial N2LO). With the spectral functions we calculate the isovector nucleon EM FFs and their derivatives at $t=0$ (EM radii, moments) using subtracted dispersion relations. We predict the values of higher FF derivatives with minimal uncertainties and explain their collective behavior. We estimate the individual proton and neutron FFs by adding an empirical parametrization of the isoscalar sector. Excellent agreement with the present low-$Q^2$ FF data is achieved up to $\sim$0.5 GeV${}^2$ for $G_E$, and up to $\sim$0.2 GeV${}^2$ for $G_M$. Our results can be used to guide the analysis of low-$Q^2$ elastic scattering data and the extraction of the proton charge radius.

   ↳ hep-phhep-latnucl-exnucl-thPRC(2018)·37 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.