1 / 13

Asymmetry of Jet k T in Longitudinal Polarized p+p Collisions in PHENIX at RHIC

R. Hobbs For the PHENIX collaboration University of New Mexico. Asymmetry of Jet k T in Longitudinal Polarized p+p Collisions in PHENIX at RHIC. Outline. Measuring transverse momentum of partons in the proton Looking for a correlation of this measurement with spin direction

aerona
Télécharger la présentation

Asymmetry of Jet k T in Longitudinal Polarized p+p Collisions in PHENIX at RHIC

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. R. Hobbs For the PHENIX collaboration University of New Mexico Asymmetry of Jet kT in Longitudinal Polarized p+p Collisions in PHENIX at RHIC

  2. Outline • Measuring transverse momentum of partons in the proton • Looking for a correlation of this measurement with spin direction • Initial measurements in Run03 • Status of Run05 • Summary Oct. 27, 2005 2

  3. * jet jTN jet fragmentation transverse momentum, jT-scaling. kT2F-2N parton transverse momentum,intrinsic + NLO radiative corrections.  kT, jT from azimuthal correl. fragmentation Oct. 27, 2005 3

  4. Origin of kT An example - J/ production. Breaks collinear factorization pTJ/=1.80.230.16 GeV/c Phys. Rev. Lett. 92, 051802, (2004). Oct. 27, 2005 4

  5. Longitudinal jet jet transverse • acoplanar in PL PT space • acoplanar in PX PY space Hard Scattering kT Longitudinal transverse • acoplanar in PL PT space • collinear in PX PY space Oct. 27, 2005 5

  6. kT from Orbital Motion kT larger kT smaller One can consider the possibility that spin-correlated transverse momentum (orbital angular momentum) may contribute to jet kT. e.g., Meng Ta-chung et al., Phys. Rev. D 40 (1989) Oct. 27, 2005 6

  7. o - h correlation functions d+Au Azimuthal correlation function Not corrected for acceptance Corrected for acceptance F Oct. 27, 2005 7

  8. p2out = p2Ta sin2 2k2Tyz2a 2k2Tyz2tx2hxh= pTa /pTt pTt jT jT pTa Jet kinematics partonic hadronic Oct. 27, 2005 8

  9. Spin Sorted Analysis • Do exactly the same analysis sorted on same and opposite helicity bunch crossings, extract <zkt>RMS and look at the difference. Same Helicity Opposite Helicity C(Δφ) C(Δφ) Δφ Δφ Oct. 27, 2005 9

  10. Run03 Data Like sign Unlike sign trigger π0 1< pTt<3 Gev/c 3<pTt<7 Gev/c Associated h 1< pTa<2.5 Gev/c Oct. 27, 2005 10

  11. Systematic Check RMS = 45 • Helicity assignments are randomized, and then the kT difference calculated for each randomized set. • The width of the distribution for all the randomized sets should be the same as our statistical errors on the previous plot. RMS = 90 Oct. 27, 2005 11

  12. Run03 Data Its too early to make a definite statement about the apparent excess as the systematic uncertainties are being evaluated. However, there is an ongoing analysis of 10x more stat. and 2x better polarization in run05  should yield a definite answer. BS variance Oct. 27, 2005 12

  13. Summary • We have an analysis tool that allows us to measure kT - initial state transverse momentum of partons. • We are studying this effect in longitudinal spin-sorted collisions to see if there is a spin-dependent coherent component of kT. • Is there a connection to parton OAM? Theoretical guidance needed! Outlook • Run05 has ~x10 statistics, so that the uncertainty reduced by factor 2-3. • It has ~x2 in polarization, so the effect grows by ~x4. Oct. 27, 2005 13

More Related