Download or read book Longitudinal Spin Transfer to Lambda and Lambda Bar Hyperons in Polarized Proton Proton Collisions at Sqrt S written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The longitudinal spin transfer, D{sub LL}, from high energy polarized protons to [Lambda] and {bar [Lambda]} hypersons has been measured for the first time in proton-proton collisions at √s = 200 GeV with the STAR detector at RHIC. The measurements cover pseudorapidity, [eta], in the range.

Download or read book Longitudinal Spin Transfer in Inclusive Lambda and Lambda Barproduct Ion in Polarized Proton proton Collisions at Sqrt S written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This contribution reports on a proof-of-principle measurement of the longitudinal spin transfer D{sub LL} in inclusive [Lambda] and [Lambda] production in polarized proton-proton collisions at a center of mass energy √s = 200 GeV. The data sample consists of about 3 x 106 minimum bias events collected in the year 2005 by the STAR experiment at RHIC with proton beam polarizations of up to 50%. The [Lambda]({bar [Lambda]}) candidates are reconstructed at mid-rapidity (

Download or read book Longitudinal Spin Transfer to Lambda and Anti lambda Hyperons Produced in Polarized Proton proton Collisions at Center of Mass Energy written by Ramon Cendejas and published by . This book was released on 2012 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies on the spin structure of the proton have been an active area of research; after the EMC experiment and subsequent experiments found that only about 30% of the total proton spin is carried by quark spins. The Relativistic Heavy Ion Collider (RHIC) is the world's first and only polarized proton collider. The Solenoidal Tracker At RHIC (STAR) has full azimuthal acceptance and is ideally suited to advance studies of the proton spin. The longitudinal spin transfer, DLL, of & lambda; and anti- & lambda; hyperons in longitudinally polarized proton-proton collisions is sensitive to quark and anti-quark polarization in the polarized proton; as well as to polarized fragmentation; and has been proposed as a possible probe of (anti- )strange quark polarization. The STAR collaboration has previously reported an initial proof-of-concept measurement of DLL of & lambda; and anti- & lambda; hyperons from a data sample obtained at sqr(s)=200 GeV in 2005. The data correspond to an integrated luminosity of 2 pb- with 50% beam polarization. Considerably larger data samples corresponding to 6.5 pb- and 25 pb- with beam polarizations of 57% at sqr(s)=200 GeV were obtained in 2006 and 2009 using an upgraded instrument. Improvements were made on the analysis procedure to reduce background contribution to the & lambda; + anti- & lambda; measurements. These new measurements of DLL form the main topic of this dissertation. The sample of hyperons residing within a jet that triggered the experiment are classified as near-side hyperons, and are analyzed separately from an away-side sample that has similar precision. In addition to DLL, the double longitudinal spin asymmetry, ALL, for the production of & lambda; and anti- & lambda; hyperons has been extracted. The dependences of DLL on pseudo-rapidity, pT, and the fragmentation ratio, z, are studied. The stated DLL from & lambda; and anti- & lambda; each disfavor one of the published model predictions for DLL for a combined & lambda; and anti- & lambda; sample, and are consistent with other predictions as well as with the preceding data. The disfavored model prediction is based on the assumption that up, down, and strange (anti- )quark spins contribute equally to polarized fragmentation into & lambda; + anti- & lambda; hyperons. Future data with improved statistical precision, including data at sqr(s)=500 GeV, are needed to discriminate between the other models.

Download or read book Measurements of Lamba and Anti Lambda Polarization in Longitudinally Polarized Proton Proton Collisions at SQRT S NN written by and published by . This book was released on 2005 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: Preliminary results for the longitudinal polarization of A and hyperons in longitudinally polarized proton-proton collisions at √s = 200 GeV are presented. The [Lambda]({bar [Lambda]}) candidates are reconstructed at mid-rapidity (

Download or read book Longitudinal Double Spin Asymmetry for Inclusive Jet Production in Polarized Proton proton Collisions at square Root Of S written by Julie Marie Millane and published by . This book was released on 2008 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present the Inclusive Jet Longitudinal Double-Spin Asymmetry for polarized protons at \s = 200 GeV. The data were taken on the STAR experiment at RHIC during the 2005 run period and cover a jet transverse momentum range of 5

Download or read book Proceedings of the 17th International Spin Physics Symposium written by Kenichi Imai and published by American Inst. of Physics. This book was released on 2007-07-02 with total page 1196 pages. Available in PDF, EPUB and Kindle. Book excerpt: Getting down to the bottom line is what this proceedings digest is all about, as any physicist will tell you: spin is the fundamental concept in physics. The applications are pretty universal due to the fact that, using spin-related phenomena, physicists are trying to reveal the fundamental principles of nature – and things don’t come much more bottom-line than that. This volume is the proceedings of the 17th International Spin Physics Symposium which is a forum to discuss spin physics and related topics.

Download or read book Longitudinal Double spin Asymmetry and Cross Section for Inclusivejet Production in Polarized Proton Collisions at Sqrt s written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report a measurement of the longitudinal double-spinasymmetry A_LL and the differential cross section for inclusivemidrapidity jet production in polarized proton collisions at sqrt(s)=200GeV. The cross section data cover transverse momenta 5

Download or read book Measurement of the Longitudinal Double Spin Asymmetry for Dijet Production in Polarized Proton Proton Collisions at Sqrt s written by Daniel L. Olvitt and published by . This book was released on 2017 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding what contributes to the intrinsic angular momentum (spin) of the proton has been a major goal of the nuclear physics community. In the 1980s, it was discovered that quarks contribute 30% to the spin of the proton. This information led to a search to find other contributions to the spin of the proton. At STAR, the double spin asymmetry (ALL) is measured as it is sensitive to the polarized gluon distribution (Dg(x)). The STAR 2009 inclusive jet ALL at sqrt(s) = 200 GeV has been incorporated into two independent global fits. These fits show for the first time a statistically significant non-zero gluon contribution to the spin of the proton in the parton momentum fraction range x > 0.05. Dijet ALL is also measured at STAR. Dijets are advantageous since the parton momentum fraction (x) of the initial partons may be reconstructed to first order from final state measurements. In 2013 STAR collected an estimated 250 pb-1 of data at sqrt(s) = 510 GeV. The higher center of mass energy will allow STAR to probe Dg(x) at x values as low as 0.02. The large statistics will allow a reduction in the uncertainties. Once the data is incorporated into future global fits, it will allow for a more precise determination of Dg(x). The 2013 dijet ALL results will be presented. The results show good agreement with both global fits and previous STAR results dijet measurements.

Download or read book Longitudinal Double spin Asymmetry and Cross Section for Inclusive Neutral Pion Production in Polarized Proton Collisions at the Square Root of Sigma written by Alan Michael Hoffman and published by . This book was released on 2009 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: Twenty years of polarized lepton-nucleon scattering experiments have found that the contribution from quark spins (1/2[delta] [sigma]) to the spin of the proton is only ~ 35%. This has lead researchers to look elsewhere, specifically to gluon spin ([delta sigma]) for a large contribution to proton spin. [delta sigma] has been only loosely constrained in polarized DIS and SIDIS experiments. Polarized proton-proton collisions at RHIC provide sensitivity to [delta sigma] through measurements of the longitudinal double-spin asymmetry, ALL. This work presents a measurement of ALL for inclusive 7ro production in polarized proton-proton collisions using the STAR detector and data from RHIC Run 6. 7r0s are abundantly produced at mid-rapidity in proton-proton collisions, making them natural candidates for studies of [delta] [sigma]. Novel techniques for reconstructing 7ros at STAR are discussed, and a measurement of the unpolarized cross section presented. Finally, the measured ALL is compared to perturbative QCD predictions and from this comparison constraints are placed on [delta] [sigma].

Download or read book Inclusive Jet and Dijet Production in Polarized Proton proton Collisions at the Square Root of Sigma written by Tai Sakuma and published by . This book was released on 2010 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: The inclusive jet cross section, the dijet cross section, and the dijet longitudinal double spin asymmetry ALL in polarized proton-proton collisions at [square root of sigma] = 200 GeV are measured with a data sample of 5.4 pbm collected with the STAR detector during RHIC Run-6. The inclusive cross section is measured as a function of jet transverse momentum PT in the range of 10

Download or read book Dijet Production in Polarized Proton proton Collisions at the Square Root of Sigma written by Matthew Hsing Hung Walker and published by . This book was released on 2011 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polarized deep inelastic scattering (DIS) experiments indicate that quarks only carry approximately 30% of the proton spin, which led to interest in measuring the contributions of other components. Through polarized proton-proton collisions at the Relativistic Heavy Ion Collider (RHIC), the world's only polarized proton collider, it is possible to make an extraction of the polarized gluon distribution function [delta]g(x). This function describes the contribution of the gluon polarization to the proton spin. This thesis presents a measurement of the p + p ---> Jet + Jet + X (dijet) cross section from the 2005 RHIC running period and a measurement of the longitudinal double spin asymmetry ALL from the 2009 RHIC running period, both made using the Solenoidal Tracker at RHIC (STAR). The cross section is measured over the invariant mass range 20

Download or read book Longitudinal Spin Transfer to the Lambda Hyperon in Semi inclusive Deep inelastic Scattering written by HERMES Collaboration and published by . This book was released on 2006 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Anti Hyperon Polarization in High Energy Pp Collisions Withpolarized Beams written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We study the longitudinal polarization of the {bar {Sigma}}−, {bar {Sigma}}, {bar {Xi}}° and {bar {Xi}} anti-hyperons in polarized high energy pp collisions at large transverse momenta, extending a recent study for the {bar {Lambda}} antihyperon. We make predictions by using different parameterizations of the polarized parton densities and models for the polarized fragmentation functions. Similar to the {bar {Lambda}} polarization, the {bar {Xi}}° and {bar {Xi}}+ polarizations are found to be sensitive to the polarized anti-strange sea, [Delta]{bar s}(x), in the nucleon. The {bar {Sigma}}− and {bar {Sigma}}+ polarizations show sensitivity to the light sea quark polarizations, [Delta]{bar u}(x) and [Delta]{bar d}(x), and their asymmetry.

Download or read book Measurement of Longitudinal Spin Transfer to Lambda Hyperons in Deep inelastic Lepton Scattering written by and published by . This book was released on 2001 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Neutral Pion Double Helicity Asymmetry in Polarized Proton Proton Collisions at the Square Root of Sigma written by William Axel Leight and published by . This book was released on 2012 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the primary goals of the spin physics program at the STAR experiment is to constrain the polarized gluon distribution function, [delta]g(X,Q2), by measuring the double longitudinal spin asymmetry, ALL, of various final-state channels. Neutral pions provide a potentially powerful final state because they are copiously produced in p+p collisions and have few backgrounds. In 2009, STAR took 14 pb-1 of integrated luminosity of 200 GeV p+p collisions, with average beam longitudinal polarization of 59%. Neutral pions produced in these collisions can be identified using STAR's large-acceptance electromagnetic calorimeter, with help from tracking from the STAR Time Projection Chamber. This work presents a measurement of the inclusive neutral pion ALL from this data, based on a new [pi]0 reconstruction algorithm. A comparison to theoretical predictions and other experimental results suggests that the current best-fit value of AG, the gluon contribution to the proton spin, is too small and that [delta]G is actually comparable in magnitude to the quark contribution to the proton spin [delta][sigma].

Download or read book Measurement of Longitudinal Spin Transfer to L63 Lambda Hyperons in Deep inelastic Lepton Scattering written by and published by . This book was released on 1999 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Precision Measurement of the Longitudinal Double spin Asymmetry for Inclusive Jet Production in Polarized Proton Collisions at u221A s written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report a new measurement of the midrapidity inclusive jet longitudinal double-spin asymmetry, ALL, in polarized pp collisions at center-of-mass energy √s = 200 GeV. The STAR data place stringent constraints on polarized parton distribution functions extracted at next-to-leading order from global analyses of inclusive deep-inelastic scattering (DIS), semi-inclusive DIS, and RHIC pp data. Lastly, the measured asymmetries provide evidence at the 3? level for positive gluon polarization in the Bjorken-x region x > 0.05 .