[Brahms-l] Fw: Release of PHENIX paper on A_LL for pi0's

FYI

----------------------------------------------------------------
Flemming Videbaek
Physics Department
Brookhaven National Laboratory

e-mail: videbaek@bnl.gov
phone: 631-344-4106
----- Original Message ----- 
From: "William A. Zajc" <zajc@nevis.columbia.edu>
To: "Thomas Kirk" <tkirk@bnl.gov>; "Mark Baker (Mark D. Baker)"
<Mark.Baker@bnl.gov>; "'Hallman, Timothy J'" <hallman@bnl.gov>; "'Videbaek,
Flemming'" <videbaek@bnl.gov>
Sent: Thursday, April 08, 2004 12:04 PM
Subject: Release of PHENIX paper on A_LL for pi0's


> Dear Tom, Mark, Tim and Flemming:
>
> The PHENIX Collaboration intends to submit a manuscript to Physical Review
Letters in one week describing our measurement of A_LL
> for pi0's in p+p collisions. The results are essentially identical to
those that have been shown at various spin conferences as
> preliminary data. The title and abstract are included below.
>
> Best regards,
>
> Bill
>
>
============================================================================
==================
>
> Title: The double helicity asymmetry in inclusive mid-rapidity $\pi^{0}$
production in polarized $p-p$ collisions at $\sqrt{s}=200$
> GeV
>
> Abstract: We present the measurement of the double longitudinal spin
asymmetry in inclusive$\pi^{0}$ production in polarized
> proton-proton collisions at $\sqrt{s}=200$ GeV.  The data were taken at
the Relativistic Heavy Ion Collider in its 2003 run, with
> average beam polarizations of 26%.  The measurements are the first of a
program to study the longitudinal spin structure of the
> proton, using strongly interacting probes, at collider energies.  The
asymmetry is presented for transverse momenta 1-5 GeV/c at
> mid-rapidity, where perturbative QCD calculations at next-to-leading order
(NLO pQCD) describe the unpolarized cross section well.
> The observed asymmetry is small and is compared with a NLO pQCD
calculation with a range of polarized gluon distributions.
>


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