Fri·Apr 3, 2015Friday·April 3, 2015

1. 01*

   A pair spectrometer for measuring multipolarities of energetic nuclear transitions

   J. Gulyás🇭🇺 · T.J. Ketel🇳🇱 · A.J. Krasznahorkay🇭🇺 · M. Csatlós🇭🇺 · L. Csige🇭🇺 · Z. Gácsi🇭🇺 · M. Hunyadi🇭🇺 · A. Krasznahorkay🇨🇭 · A. Vitéz🇭🇺 · T.G. Tornyi🇭🇺

   A multi-detector array has been designed and constructed for the simultaneous measurement of energy- and angular correlations of electron-positron pairs. Experimental results are obtained over a wide angular range for high-energy transitions in 16O, 12C and 8Be. A comparison with GEANT simulations demonstrates that angular correlations between 50 and 180 degrees of the electron-positron pairs in the energy range between 6 and 18 MeV can be determined with sufficient resolution and efficiency.

   nucl-exNucl.Instrum.Meth.A(2016)·56 citations
2. 02*

   Effective distributions of quasi-particles for thermal photons

   Akihiko Monnai🇺🇸

   It has been found in recent heavy-ion experiments that the second and the third flow harmonics of direct photons are larger than most theoretical predictions. In this study, I construct effective parton phase-space distributions with in-medium interaction using quasi-particle models so that they are consistent with a lattice QCD equation of state. Then I investigate their effects on thermal photons using a hydrodynamic model. Numerical results indicate that elliptic flow and transverse momentum spectra are modified by the corrections to Fermi-Dirac and Bose-Einstein distributions.

   ↳ nucl-thhep-phnucl-exPRC(2015)·7 citations
3. 03*

   Observation of Transverse Spin-Dependent Azimuthal Correlations of Charged Pion Pairs in $p^{\uparrow }+p$ at $\sqrt{s}=200$ GeV

   STAR Collaboration: L. Adamczyk🇵🇱 · J. K. Adkins🇺🇸 · G. Agakishiev🇷🇺 · M. M. Aggarwal🇮🇳 · Z. Ahammed🇮🇳 · I. Alekseev🇷🇺 · J. Alford🇺🇸 · A. Aparin🇷🇺 · D. Arkhipkin🇺🇸 · E. C. Aschenauer🇺🇸 · G. S. Averichev🇷🇺 · A. Banerjee🇮🇳 and 320 other authors

   We report the observation of transverse polarization-dependent azimuthal correlations in charged pion pair production with the STAR experiment in $p^{\uparrow }+p$ collisions at RHIC. These correlations directly probe quark transversity distributions. We measure signals in excess of five standard deviations at high transverse momenta, at high pseudorapidities eta>0.5, and for pair masses around the mass of the rho-meson. This is the first direct transversity measurement in p+p collisions. Comparing the results to data from lepton-nucleon scattering will test the universality of these spin-dependent quantities.

   ↳ hep-exnucl-exPRL(2015)·57 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.