Longitudinal Double Spin Asymmetry Of Forward Neutral Pions From 510 Gev Polarized Proton Proton Collisions At Star
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| Author | : Christopher John Dilks |
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| Release | : 2018 |
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Download Longitudinal Double-spin Asymmetry of Forward Neutral Pions from 510 GeV Polarized Proton-proton Collisions at STAR. Book in PDF, Epub and Kindle
Longitudinally polarized proton-proton scattering experiments provide access to the gluon polarizationcontribution to the overall proton spin via a measurement of the longitudinal double-spin asymmetry,$A_{LL}$. During RHIC data-taking periods in 2012 and 2013, a significant sample of $\pi^0$s scattered inthe forward direction was acquired from proton-proton collisions with a center-of-mass energy of 510 GeVand beam polarizations of $\sim 55\%$. The $\pi^0$ kinematics were measured by the STAR Forward MesonSpectrometer, an electromagnetic calorimeter spanning a forward pseudorapidity range of $2.5
| Author | : William Axel Leight |
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| Total Pages | : 112 |
| Release | : 2012 |
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Download Neutral Pion Double Helicity Asymmetry in Polarized Proton-Proton Collisions at [the Square Root of Sigma] Book in PDF, Epub and Kindle
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].
| Author | : Alan Michael Hoffman |
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| Total Pages | : 126 |
| Release | : 2009 |
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Download Longitudinal Double-spin Asymmetry and Cross Section for Inclusive Neutral Pion Production in Polarized Proton Collisions at [the Square Root of Sigma] Book in PDF, Epub and Kindle
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].
| Author | : Julie Marie Millane |
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| Total Pages | : 204 |
| Release | : 2008 |
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Download Longitudinal Double Spin Asymmetry for Inclusive Jet Production in Polarized Proton-proton Collisions at [square Root Of] S Book in PDF, Epub and Kindle
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
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| Release | : 2015 |
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Download Precision Measurement of the Longitudinal Double-spin Asymmetry for Inclusive Jet Production in Polarized Proton Collisions at {u221A}s Book in PDF, Epub and Kindle
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 .
| Author | : Daniel L. Olvitt |
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| Total Pages | : 147 |
| Release | : 2017 |
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Download Measurement of the Longitudinal Double Spin Asymmetry for Dijet Production in Polarized Proton+Proton Collisions at Sqrt(s) Book in PDF, Epub and Kindle
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.
| Author | : Adam Philip Kocoloski |
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| Total Pages | : 105 |
| Release | : 2010 |
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Download Measurement of Longitudinal Double Spin Asymmetries of [pi]+/- Production in P[over-arrow] + P[over-arrow] Collisions at [sqrt]s Book in PDF, Epub and Kindle
Spin dependent measurements provide incisive tests for modern theories of particle physics. The discovery that the integral of the quark helicity distribution is much too small to account for the spin of the proton is an excellent case in point. It inspired an intense period of theoretical scrutiny and a new generation of experiments to study [Delta]g, the helicity distribution of gluons in the nucleon. In particular, the unique polarized proton collider at RHIC enables a class of asymmetry measurements that are directly sensitive to gluon polarization. The STAR experiment at RHIC measures the double spin asymmetry A[subscript LL] for a variety of final states in collisions of longitudinally polarized protons in order to constrain [Delta]g. Asymmetries for mid-rapidity charged pion production benefit from large cross sections and the excellent tracking and particle identification capabilities of the STAR Time Projection Chamber. This thesis presents the first measurements of charged pion A[subscript LL] at STAR. The measurements are compared to predictions based on perturbative QCD calculations and from this comparison model-dependent constraints are placed on the integral gluon polarization [Delta]G.
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| Total Pages | : 3 |
| Release | : 2005 |
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Download MEASUREMENT OF THE DOUBLE LONGITUDINAL SPIN ASYMMETRY IN INCLUSIVE JET PRODUCTION IN POLARIZED P+P COLLISIONS AT S**ư Book in PDF, Epub and Kindle
We present preliminary results for the first measurements of the double longitudinal spin asymmetry A{sub LL} in inclusive jet production at mid-rapidity in polarized proton-proton collisions at √s = 200 GeV. The data amount to ≈ 0.5 pb−1 collected at RHIC in 2003 and 2004 with beam polarizations up to 45%. The jet transverse energies are in the range of 5
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| Release | : 1938 |
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Download רסיסים מהעבר הקרוב Book in PDF, Epub and Kindle
| Author | : Amani Kraishan |
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| Total Pages | : 117 |
| Release | : 2018 |
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Download MEASUREMENT OF LONGITUDINAL SINGLE-SPIN ASYMMETRY FOR W± BOSON PRODUCTION IN POLARIZED PROTON-PROTON COLLISIONS AT STAR AT FORWARD RAPIDITY Book in PDF, Epub and Kindle
