Oct. 12, 2007 Imran Younus k T Asymmetry in Longitudinally Polarized p +p Collisions at PHENIX

10/12/2007Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"2 Origin of Jet k T Another Possibility: Spin-Correlated transverse momentum – partonic orbital angular momentum Assume other contributions have no spin dependence… We can perhaps measure using jet k T spin asymmetry. Possible Effect in double longitudinal spin – Idea proposed for the Drell-Yan process by M.Ta-chung et. al. (Phys. Rev. D40 p.769, 1989) – Same idea for jets suggested by Douglas Fields. jet p T kTkT

Accessing Orbital Angular Momentum Integrate over b, left with residual  k T 2  Central Collisions  Smaller  k T 2  Peripheral Collisions  Smaller  k T 2  Un-like Helicity Central Collisions  Smaller  k T 2  Peripheral Collisions  Larger  k T 2  Like Helicity 10/12/20073Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"

10/12/2007Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"4 PHENIX Detector Central Arms: |  |<0.35,  =2  90 0 Charged particle ID and tracking; photon ID. EM Calorimetry. Muon Arm: 1.2<|  |<2.4 Muon ID and tracking. Global Detectors Collision trigger Collision vertex characterization Relative luminosity Local Polarimetry Philosophy: – High resolution at the cost of acceptance – High rate capable DAQ – Excellent trigger capability for rare events

10/12/2007Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"5 How does PHENIX measure jet k T  j T  - Jet fragmentation transverse momentum.  k T  - Partonic transverse momentum.  o - h  azimuthal correlation jTjT jTjT p Tt p Ta  Trigger  0 far near

10/12/2007Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"6 Zero k T How does PHENIX measure jet k T Non-Zero k T  kT  kT Intra-jet pairs angular width :  near   j T  Inter-jet pairs angular width :  far   j T 

10/12/2007Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"7 For details, see hep-ex/ Jet Kinematics 

10/12/2007Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"8 Min photon energy > 0.2 GeV (for both PbSc and PbGl). Two photon energy asymmetry < 0.8. π° Identificaton

10/12/2007Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"9 Correlation Function Red – real (raw Δφ) Blue – background (mixed events) charged track p T :

10/12/2007Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"10 Fit Function Black – real (raw Δφ) Blue – Fit from above equation

10/12/2007Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"11 k T results for unpolarized case  j T  = 585 ± 6(stat) ± 15(syst) MeV  k T  = 2.68 ± 0.07(stat) ± 0.34 (syst) GeV Phys. Rev. D 74, (2006)

10/12/2007Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"12 Fit Results Red – Like helicity (++ & --) Blue – Unlike helicity (+- & -+)

10/12/2007Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"13 Need z t and x h Go from p out → Simple parameterizations of z t and x h taken from Phys. Rev. D 74, (2006) Our results are not sensitive to this parameterization – only needed to set the scale Use these parameterizations to estimate

6/18/2007 Douglas Fields, 2007 RHIC & AGS Annual Users' Meeting: "Probing the nucleon's spin structure with longitudinally polarized beams" 14 Preliminary Results Take the difference Like – Unlike helicities Normalized by beam polarizations j T asymmetry small (32 ± 24MeV/c out of ~580MeV/c for unpolarized) k T asymmetry not small (672 ± 387MeV/c out of ~3GeV for unpolarized)

10/12/2007Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"15 Summary We have an analysis tool that allows us to measure k T – di-hadron azimuthal correlation. We are studying this effect in longitudinal spin- sorted collisions to see if there is a spin-dependent coherent component of k T. Is there a connection to parton OAM? Theoretical guidance needed! Look forward to Run6 data analysis (~ x3 in F.O.M.) soon!

10/12/2007Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"16 Integrating over Impact Parameter Drell-Yan pair production in polarized p+p collisions. (Meng Ta-Chung et al. Phys. Rev. D 1989) k TR k PR k TR k PR Like Helicity Un-like Helicity Averaging over D(b): Integrating over impact parameter b:

10/12/2007Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"17 Pythia Studies Input k T Expected & Extracted k T

10/12/2007Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"18 Bunch Shuffling (p out ) p out / δp out Mean consistent with zero and width consistent with 1.

10/12/2007Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"19 Bunch Shuffling Summary

10/12/2007Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"20 Bunch Shuffling ( σ near ) σ near / δσ near Mean consistent with zero and width consistent with 1.

10/12/2007Imran Younus DNP 2007: "Mini-Symposium on Studying the Orbital Structure of the Proton with Di-Jets at RHIC"21 RHIC as Polarized Proton Collider L max = 2  s -1 cm -2 70% Polarization50   s  500 GeV