Physics With Polarized Protons at RHIC II

E. Sichtermann, LBL M. Stratmann, Regensburg M. G. Perdekamp, UIUC/RBRC

o Proton Structure and RHIC Spin: A new experimental method to explore the spin structure of the

fundamental bound state of QCD

o New Opportunities at high luminosities (+ upgrades)

How is a transversely polarized proton different from a longitudinal polarized proton? What can we learn from the difference?

What is the role of strange quarks in the proton?

Precision measurement of the nucleon (p+3He?) helicity structure.

Precision cross section measurements and their QCD analysis.

Physics with Polarized Protons at RHIC II 2 November 11th

The Big Picture: Structure of Basic Building Blocks of Matter

⇔ Fundamental Forces in Nature

fundamental

bound stateof matter

interaction between

the constituents of

the bound state

measurementswith new tools+ betterprecision

theory predictionsincreasingly quantitative

Physics with Polarized Protons at RHIC II 3 November 11th

Structure of the Basic Building Blocks of Matter vs Fundamental Forces in Nature

hydrogenatom

QuantumElectro Dynamics

Doppler freesaturationspectroscopy

Lamb shift

Example: Doppler free saturation spectroscopy Lamb shift

Tomonaga,Feynman, Schwinger

Lamb

Physics with Polarized Protons at RHIC II November 11th

AGSLINACBOOSTER

Polarized Source

Spin RotatorsPartial Snake

Siberian Snakes

200 MeV Polarimeter

AGS Internal Polarimeter

Rf Dipole

RHIC pC Polarimeters Absolute Polarimeter (H jet)

PHENIX

BRAHMS & PP2PP

STAR

Siberian Snakes

AGS pC Polarimeter

Helical Partial SnakeStrong Snake

Spin Flipper

A novel experimental methodA novel experimental method: Probing Proton Spin Structure in High Energy Polarized Proton Collisions at RHIC

RIKEN & BNL

Physics with Polarized Protons at RHIC II 5 November 11th

The Proton as QCD Laboratory

2000

2010

1995

2007

ongoing

ongoing

2015 ?

2015

q(x) -- G(x) -- ∆q(x) – DVCS -- δq(x) -- Sivers -- ∆G(x) -- ∆q(x) -- ∆s(x)

SLAC DIS, polarized-DIS

CERN DIS, polarized-DIS

FNAL DIS, pp

DESY collider-DIS, polarized-DIS

JLAB DIS, polarized-DIS

RHIC I+II polarized-pp

e-RHIC polarized collider DIS

GSI-PAX polarized anti-protons

Physics with Polarized Protons at RHIC II 6 November 11th

Physics Channels for RHIC II

Transverse Spin Physics

o Measure transversity-, Sivers- and Boer-Mulders distributions in Drell Yan o AN in direct photon production

direct measurements with good statistical resolution explore origin of transverse spin phenomena in QCD study transverse proton spin structure unique test of factorization & universality for kT-dependent distribution functions possible connection to orbital angular momentum

Polarization of the strange sea

o Access ∆s(x) through inclusive anti-Lambda production and charm associated W-production (very luminosity hungry)

study polarization of the strange sea verify ∆s from DIS (spin crisis!), neutrinos

Physics with Polarized Protons at RHIC II 7 November 11th

Physics Channels for RHIC II

Precision measurement of the proton helicity structure

o ∆G(x) and ∆q(x), ∆q(x) with high luminosity in multiple channels with available detector upgrades. Extend measurements to 3He neutron. (can this be done with high polarization + intensity??) minimize errors and increase x-coverage of ∆G(x) for precision measurement of the first moment of the spin-dependent gluon distribution ∆G=ʃ ∆G(x)dx:

minimize errors in

observe scale evolution of the first moment.

global QCD analysis for best knowledge of polarized nucleon structure + pdfs

Precision cross section measurements + QCD analysis

o Measure cross sections in direct photon production, inclusive jet + hadron production as input to QCD analysis to improve knowledge of

G(x) at large x Gluon fragmentation function

GLz 2

1

2

1

Physics with Polarized Protons at RHIC II 8 November 11th

Present knowledge of the Gluon Distribution Function G(x,Q2)

J. Pumplin et.al JEHP 0207:012 (2002)

3.16GeVQ at u

3.16GeVQ at d

10-410-3 10-2 10-1 0.5 x

gluon

down

up-quarks

anti-down

Quark and Gluon Distributions

error on G(x,Q2)

error for u(x,Q2)

+/- 10%

+/- 5% +/- 5%

error for d(x,Q2)

10-410-3 10-2 10-1 0.5 x

CTEQ6: use DGLAP Q2-evolution of

quark and gluon distributions to extract q(x,Q2)and G(x,Q2) from global fit to data sets at different scales Q2.

H1 + Zeus F2

CDF + D0 Jets

CTEQ5M1

CTEQ6M

!

Physics with Polarized Protons at RHIC II 9 November 11th

Work in Progress: general working group meeting October 7 +8 at BNL

Transverse spin physics: S. Menzel (Bochum), L. Gamberg (Penn State), J. Soffer (Marseille), M. Burkardt (New Mexico), F. Yuan (RBRC), M. Radici (Pavia) (there was also a very well attend RBRC workshop organized by Vogelsang and Yuan in June)

Hyperons : Z. Liang (Shandong), Q. Xu (Shandong+LBL), K. Sudoh (KEK)

W-physics: P. Nadolsky (Argonne), K. Sudoh (KEK), J. Soffer (Marseille)

Beyond the SM: J. Soffer (Marseille), D. Maitre (Zurich)

+ usual RHIC spin crowd

Work in progress; eg. projections for access toStrange polarization in lambda production.Final document will be based on writtencontributions from working group participants December

Physics with Polarized Protons at RHIC II 10

November 11th

Transverse spin program at RHIC is luminosity limited

AN yes, very good

AN(back-to-back) good

AT (Collins FF) fair

AT (Interference FF) limited

ATT (Jets) not studied experimentally

AT (Drell Yan) ---

ATT( Drell Yan) ---

Direct photons --- (AN,AT(CFF, IFF))

RHIC by 2009 at 200 GeV

∫Ldt ~275pb-1 delivered

∫Ldt ~100pb-1 accepted(eg. PHENIX: vertex cut,trigger efficiencies, dutyfactor)

∫Ldt ~25 pb-1 transverse

RH

IC II

Physics channel Luminosity?

Dedicated Drell Yan experiment for transverse spin physics at PHOBOS IR?

Physics with Polarized Protons at RHIC II 11

November 11th

Transversity : correlation between transverse proton spin and quark spin

Sivers : correlation between transverse proton spin and quark transverse momentum

Boer/Mulders: correlation between transverse quark spin and quark transverse momentum

Transversity vs Sivers vs Boer-Mulders in Drell Yan

)()( 21 xqxqATT

M

SkPkxfxqA PTq

TT

)ˆ(

),()( 2211

M

SkPkxh

M

SkPkxhN qqqq

)ˆ(),(

)ˆ(),()( 2

212

11

Physics with Polarized Protons at RHIC II 12

November 11th

Sivers-Asymmetries, AT in Drell Yan (S. Menzel)

Sensitivity to anti-quark Sivers distribution (not probed at GSI)

Sign with respect to DIS! Brodsky, Hwang, Schmidt Collins Boer, Mulders, Pijlman Belitsky, Ji, Yuan

Physics with Polarized Protons at RHIC II 13

November 11th

Sivers-Asymmetries, AT in Drell Yan (S. Menzel)

Sensitivity to anti-quark Sivers distribution (not probed at GSI)

Physics with Polarized Protons at RHIC II 14

November 11th

Sivers-Asymmetries, AT in Drell Yan (S. Menzel)

STAR for 125pb-1

Dedicated DY Experiment1250 pb-1

(fraction of transverseRunning + mini quads)

“entrance door”for DIS colleaguesInteressted in e-RHIC

Physics with Polarized Protons at RHIC II 15

November 11th

Projections for pp at 200 GeV and 1250 pb-1

ATT for Drell Yan with dedicated DY detector

projections for 1250pb-1 of running,5-10% higher polarization, with RHIC II luminosities and large acceptance

Drell Yan1.25fb-1, large acceptance detector for Drell Yan

This measurement appears to bealso possible at 500 GeV

Physics with Polarized Protons at RHIC II 16

November 11th

Physics with Polarized Protons at RHIC II 17

November 11th

K. Sudoh

Physics with Polarized Protons at RHIC II 18

November 11th

K. Sudoh

AL(W+)

AL(W+)

sensitivity to ∆s seemsdifficult, workin progress!

Physics with Polarized Protons at RHIC II 19

November 11th

Summary of RHIC II Physics Channels for Polarized Protons

o Active studies underway to evaluate the benefit of RHIC II luminosities and upgrades to the spin physics program (complete in December)

o Physics case under study:

How is a transversely polarized proton different from a longitudinal polarized proton? What can we learn from the difference?

What is the role of strange quarks in the proton?

Precision measurement of the nucleon (p+3He?) helicity structure.

Precision cross section measurements and their QCD analysis.

Physics with Polarized Protons at RHIC II 20

November 11th

The Structure of Matter: The Atomic Hypothesis

If, in some cataclysm, all of scientific knowledge were to bedestroyed, and only one sentence passed on to the next generationof creatures, what statement would contain the most informationin the fewest words? I believe it is the atomic hypothesis, that all things are made of atoms -- little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another. In that one sentence, you will see, there is an enormous amount of information about the world, if just a little imagination and thinking are applied. Richard Feynman

Physics with Polarized Protons at RHIC II 21

November 11th

Leukipp and Demokrit (~ 450-400 bc) formulated the

atomic hypothesis:

There are small particles, atoms, of which

all matter is made and which cannot be divided

in smaller parts

An Old (and fundamental!) Question: What is the structure of matter in the Universe?

Physics with Polarized Protons at RHIC II 22

November 11th

Summary

Structure and origin of matter have been subject ofcentury long investigation first in philosophy and overthe last two centuries also in the natural sciences.

We well may be the generation who will see thesolution of a 2500 year old puzzle. This are excitingtimes!

RHIC Spin (I+II) provides a powerful newexperimental method to study the structure of the nucleon