Spin Physics with STAR at RHIC

STAR collected data in proton-proton collisions at sqrt(s)=200 GeV with transverse and longitudinal beam polarizations during the initial running periods in 2002--2004 at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. Results on the single transverse spin asymmetries in the production of high energy forward neutral pions and of forward charged hadrons will be presented. Data have been obtained for double longitudinal asymmetries in inclusive jet production in 2003 and 2004. These data provide sensitivity to the polarization of gluons in the proton. In the future, we aim to determine the gluon polarization over a wide kinematic range using coincidences of direct photons and jets. Furthermore, we aim to determine the polarizations of the u, bar(u), d and bar(d) quarks in the proton by measuring single longitudinal spin asymmetries in the production of weak bosons at sqrt(s) = 500$ GeV.Comment: Prepared for the 32nd International Conference on High Energy Physics (ICHEP'04), 6 pages, 4 figure

Local Polarimetry for Proton Beams with the STAR Beam Beam Counters

STAR collected data in proton-proton collisions at sqrt(s)=200 GeV with transverse and longitudinal beam polarizations during the 2003 running period at RHIC. We present preliminary results on single transverse spin asymmetries A_N in the production of forward charged hadrons detected with the Beam-Beam Counters (BBC). The asymmetries A_N measured at pseudorapidities 3.9 < |eta| < 5.0 are found to be of the order of 0.01 while asymmetries measured at smaller pseudorapidities 3.4 < |eta| < 3.9 are found to be consistent with zero. The BBC and its associated scaler system for fast data recording provides the first local polarimeter at STAR. The setup has been sucessfully used to tune the spin rotator magnets and to verify longitudinal polarization at STAR.Comment: 5 pages, 4 figures; contribution to the Proceedings of the 16th International Spin Physics Symposium, October 11-16, 2004, ICTP, Trieste, Ital

First search for extraterrestrial neutrino-induced cascades with IceCube

We report on the first search for extra-terrestrial neutrino-induced cascades in IceCube. The analyzed data were collected in the year 2007 when 22 detector strings were installed and operated. We will discuss the analysis methods used to reconstruct cascades and to suppress backgrounds. Simulated neutrino signal events with a E-2 energy spectrum, which pass the background rejection criteria, are reconstructed with a resolution dlogE ~ 0.27 in the energy range from ~20 TeV to a few PeV. We present the range of the diffuse flux of extra-terrestrial neutrinos in the cascade channel in IceCube within which we expect to be able to put a limit.Comment: 4 pages, 3 figures. To appear in the 31st International Cosmic Ray Conference (ICRC 2009) proceedings, Lodz, Poland, 7-15 200

Spin physics with STAR

The STAR collaboration aims to study polarized proton-proton collisions at RHIC. The emphasis of the spin run this year is on transverse single spin asymmetries. Beyond 2001, we aim to determine directly and precisely the gluon polarization, as well as the polarizations of the u, $\bar{u}$, d and $\bar{d}$ quarks in the proton by measuring in addition longitudinal and double spin asymmetries. Furthermore, we aim to measure for the first time the quark transversity distributions. These measurements will improve substantially the knowledge and understanding of the spin structure of the nucleon.Comment: 9 pages, 3 figures. Talk presented at The 3rd Circum-Pan-Pacific Symposium on "High Energy Spin Physics" October 8-13 2001, Beijing, Chin

Spin dependent structure function g1g_1 at small xx and small Q2Q^2

Theoretical expectations concerning the low $x$ and low $Q^2$ behaviour of $g_1$ are summarized and compared with the recent SMC data.Comment: 4 pages, plain LATEX, 1 eps figure; contribution to 3rd UK Phenomenology Workshop on HERA Physics, St. John's College, Durham, UK, September 199

Longitudinal spin transfer of Lambda and anti-Lambda in polarized pp collisions at \sqrt s=200 GeV at STAR

We report our measurement on longitudinal spin transfer, D_LL, from high energy polarized protons to $\Lambda$ and $\bar{\Lambda}$ hyperons in proton-proton collisions at $\sqrt{s} = 200 GeV$ with the STAR detector at RHIC. The current measurements cover $\Lambda$, $\bar\Lambda$ pseudorapidity $|\eta| < 1.2$ and transverse momenta $p_T$ up to $4GeV/c$ using the data taken in 2005. The longitudinal spin transfer is found to be D_LL= -0.03\pm 0.13 (stat) \pm 0.04(syst)$for inclusive$\Lambda$and$D_{LL} = -0.12 \pm 0.08(stat) \pm 0.03(syst)$for inclusive$\bar{\Lambda}$hyperons with$ = 0.5$and$ = 3.7 GeV/c$. The prospects with 2009 data and the future measurements are also given.Comment: 6 pages, 3 figures, presentation at the SPIN2010 International Symposium, Juelich (Germany), Sep. 27-Oct. 2, 201

Spin dependent structure function g_1 at low x and low Q^2

Theoretical description of the spin dependent structure function g_1(x,Q^2) in the region of low values of x and Q^2 is presented. It contains the Vector Meson Dominance contribution and the QCD improved parton model suitably extended to the low Q^2 domain. Theoretical predictions are compared with the recent experimental data in the low x, low Q^2 region