# Presentation: 273322

## Drell Yan Measurements at RHIC II 

-  **Matthias Grosse Perdekamp, U of Illinois and RBRC**
**  **

-   **Strong Interaction Physics at BNL**
-        RHIC  RHIC II  e-RHIC
**  ****RHIC II**
** **
-        Luminosity and Detector Upgrades
-        Overview of the Physics Program
-   **Transverse Spin Physics**
**      ** Collins and
-             Interference Fragmentation
-        Drell Yan

**pp2pp**

## Strong Interaction Physics at

**    ****Temperatures and Densities**
-     ion-ion collisions (Cu-Cu, Au-Au: √sNN=22.5, 62, 130, 200 GeV)
**  ****Proton Spin Structure**
** **
-     polarized proton-proton collisions (p-p: √s=62.4, 200, 500 GeV)
-   **Low-x and high parton densities**
**    **ion-deuteron collisions (d-Au: √sNN=200 GeV)
**    **

*very active field: *
*> 90 PRL letters *
*in the first 6 years  *

- 10 x higher luminosity, detector upgrades

- ∫RHICLdt  2 fb-1, high luminosity transverse spin running?

- high luminosity, forward detector upgrades

- polarized e-p

- e-A scattering

**RHIC II**

**e-RHIC**

**RHIC**

- RHIC II*  *

## 
Electron Cooling in RHIC to increase luminosity for HI by factor 10

Detector Upgrades in PHENIX and STAR

- Electron Cooling in RHIC to increase luminosity for HI by factor 10
- Detector Upgrades in PHENIX and STAR

-  RHIC II – Definition

- RHIC II upgrades will be carefully coordinated
- with the effort to build a electron ion collider
-  RHIC as “QCD Lab”

- target date
-     2012

**Scope and schedule **
**are presently reviewed **
**in context of the long **
**range planning **
**process**

## RHIC II: Luminosity Upgrade with Electron Cooling 

- RHIC II: Luminosity Upgrade with Electron Cooling
-                                                                                                       (from Thomas Roser)

## RHIC II Schedule: Detector Upgrades + Luminosity 

- Luminosity upgrade

- High statistics Au-Au, 500 GeV pp    RHIC II

- RHIC II Schedule: Detector Upgrades + Luminosity

- Tom Ludlam

## 
Factor 2-3 increase in pp luminosity 

Small improvements in polarization

Maximum energy √s = 650 GeV

Polarized 3He2+ beams may be possible

Mini-quads at the IRs might provide additional increase in luminosity.

- Factor 2-3 increase in pp luminosity
- Small improvements in polarization
- Maximum energy √s = 650 GeV
- Polarized 3He2+ beams may be possible
- Mini-quads at the IRs might provide additional increase in luminosity.

-  p-p Expectations for the                    RHIC II Luminosity Upgrade

- In light of the ongoing discussion related to the long range
- plan new ideas for luminosity improvements and possibly
- polarized deuterons are being discussed.

## Luminosity Projection (electron cooling only, no mini-quads)

- Wolfram Fischer

## RHIC II:  Upgrades in STAR and PHENIX

**RHIC II:  Upgrades in STAR and PHENIX**

**FMS ****(Forward Meson Spectrometer)**
**TOF **
**HFT ****(Heavy Flavor Tracker)**
**Forward Tracking Upgrade**
**DAQ 1000**

**HBD ****(Hadron Blind Detector)**
**Silicon (****VTX****, FVTX)**
**Muon Trigger**
**Forward Calorimeter**

**Luminosity expectations (example, PHENIX)**
**∫****Ldt ≈    15 pb-1       RHIC run 2 – run 6 **
**∫****Ldt ≈    85 pb-1       2007 – 2012, ****√s=200 GeV**
**∫****Ldt ≈   300 pb-1      2008 – 2012, √s=500 GeV**
**∫****Ldt ≈ 1300 pb-1      2013 – 2016, √s=500 GeV**
**Upgrades will be available for most of**
**    ****RHIC spin luminosity!**

**  ****Improvement**
**              ****in  luminosity:       *****∫Ldt   ~ x 100***
**              ****in figure of merit:  *****P******4****** ******∫Ldt****  ~ ****x 300***

## RHIC II Science Workshops: Spin Physics 

**Transverse spin physics:****  S. Menzel (Bochum), L. Gamberg (Penn State), J. Soffer (Marseille),**
**                                          ****M. Burkardt (New Mexico), F. Yuan (RBRC), M. Radici (Pavia)**
**                                        **
**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)**
- Talks at _[http://rhicii-science.bnl.gov/spin/](http://rhicii-science.bnl.gov/spin/)_  Organizers: Ernst Sichterman, Marco Stratmann, MGP
**                              **
**              **

**BNL, October 7-8, 2005**

- RHIC II white paper
- http://www.bnl.gov/physics/rhicIIscience/docs/rhic2_wp_draft_dec30.pdf
- Spin working group report
- http://rhicii-science.bnl.gov/spin/rhicii-spin-20060127.pdf
- Drell Yan white paper (input to the long range planning effort)
- _http://thy.phy.bnl.gov/~vogelsan/drellyan1/dy_final.ps_

## 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.
-                          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
-                          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

- (RHIC II Spin Working Group.)

## Physics Channels for RHIC II

**Transverse Spin Physics**
-                 o Extract transversity quark distributions from precision
-                    measurements of asymmetries in Collins- and interference
-                    fragmentation.
-                 o Measure Sivers- and transversity-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

- (RHIC II Spin Working Group.)

##  Transverse Spin Physics at RHIC with Large ∫Ldt 

** **
**Sivers           :    correlation between transverse proton                                            ****	****             spin and quark transverse momentum**
**Boer/Mulders:    correlation  between transverse quark spin                          ****	****             and quark transverse momentum**

-  **Transverse Spin Physics at RHIC with Large ****∫Ldt**

**Collins and**
**Interference FF**
**∫****Ldt > 30 pb****-1**
**Drell Yan**
**∫****Ldt > 1000 pb****-1**

**A****T ****in Drell Yan**
**∫****Ldt ~ 250 pb****-1**

**A(****φ****0****)**** Drell Yan**
**?, not studied**

## Transversity, Sivers and Boer Muldersin the Proton Wavefunction

** **
**Sivers           :    correlation between transverse proton                                            ****	****             spin and quark transverse momentum**
**Boer/Mulders:    correlation  between transverse quark                         ****	****             spin and quark transverse momentum**

- Transversity, Sivers and Boer Muldersin the Proton Wavefunction

**S****p****– S****q ****– coupling ?**

**S****p****- L****q****– coupling ?? **

**S****q****- L****q****– coupling ?? **

## 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, Ws         ---
- (AN,AT(CFF, IFF))

**RHIC by 2009 at 200 GeV**
- ∫Ldt ~275pb-1 delivered
- ∫Ldt ~100pb-1 accepted
- (eg. PHENIX: vertex cut,
- trigger efficiencies, duty
- factor)
-  **∫****Ldt ~25 pb****-1**** transverse**** **

**RHIC II**

-      **Physics channel         Luminosity?**

-  Dedicated Drell Yan
-      experiment for transverse
-      spin physics at RHIC ?

## Transversity from spin dependent fragmentation

     AT  in p-p and in SIDIS
     Collins and IFF asymmetries from e+e-
     Global QCD analysis

     (for a discussion of the Collins effect see Feng Yuan’s
      talk from yesterday)

-      AT  in p-p and in SIDIS
-      Collins and IFF asymmetries from e+e-
-      Global QCD analysis
-      (for a discussion of the Collins effect see Feng Yuan’s
-       talk from yesterday)

## Transversity + Tensor Charge froma Global Analysis of e-p, p-p and e+e-

- Transversity + Tensor Charge froma Global Analysis of e-p, p-p and e+e-

- Transversity
- Tensor Charge

-  Lattice QCD: Tensor Charge

- Factorization
-          +
-  Universality ?!

**Belle**

**RHIC / GSI**

- Theory

## Transversity from Inter-                  ference Fragmentation in pp

- Transversity from Inter-                  ference Fragmentation in pp

- (Efremov, Collins, Heppelman, Ladinsky,
- Atru, Jaffe, Jin, Tan, Radici, Jacob, Bacchetta)

**QCD analysis of Belle IFF and RHIC**
**A****T ****in IFF to extract transversity**

## Projected Errors at for ∫Ldt=125 pb-1 at RHIC II

- Projected statistical errors in one invariant
- mass bin 800 MeV < m < 950 MeV

- Projected Errors at for ∫Ldt=125 pb-1 at RHIC II

- 1%

**2%**

**IFF from Belle**
**A****T**** from STAR+PHENIX**

## Sivers in SIDIS vs Drell Yan

- Important test at RHIC of the _fundamental QCD prediction_ of the_ _non-universality of the Sivers effect!
- requires very high luminosity (~ 250pb-1)

## DY vs SIDIS, what do we learn?

**DY vs SIDIS, what do we learn?**

**The Sivers effect arises from soft gluon interactions in the**
**final state (SIDIS) or initial state (Drell Yan).**
**Need to modify naïve concepts of factorization which**
**reduce hard scattering to partonic processes and neglect soft**
**gluon interactions in the initial or final state: hard scattering**
**matrix elements are modified with gauge link integrals that**
**account for initial and final state soft gluon exchange.**
**A modified concept of universality has been obtained which shows**
**how the presence of initial or final state interactions can impact**
**transverse momentum dependent distribution; eg. the Sivers**
**function changes sign between SIDS and Drell Yan! **
**There may be exciting applications elsewhere, eg. other transverse**
**momentum dependent effects or the understanding nuclear effects **
**in hard scattering. **

## Non-universality of Sivers Asymmetries:

**Simple QED**
**example:**

**DIS: attractive**

**Drell-Yan: repulsive**

**Same in**** ****Q****C****D****:**

**As a result:**

_**Non-universality**_** of Sivers Asymmetries:**
**Unique Prediction of Gauge Theory !**

*from Werner*
*Voglesang*

## Drell Yan at RHIC

- _http://thy.phy.bnl.gov/~vogelsan/drellyan1/dy_final.ps_

- Large x  forward rapidity (Les Bland)

-  Heavy flavor background (Ming Liu)

- Υ-states

- J/Ψ

- Drell Yan

- Ψ’

- charm

- bottom

- 4 GeV < Q < 10 GeV
- b-background: use FVTX

##   Experiment SIDIS vs Drell Yan:  Sivers|DIS= − Sivers|DY

-   ***0.1        0.2        0.3   x***

-   ***Sivers Amplitude***

**0**

-   **Experiment SIDIS vs Drell Yan:  ****Sivers|****DIS****= − Sivers|****DY**
** ******* Test**** ****QCD Prediction of Non-Universality *****

- HERMES Sivers Results

- Markus Diefenthaler
- DIS Workshop
- Műnchen, April 2007

**0**

- RHIC II  Drell Yan Projections

- Feng Yuan
- Werner Vogelsang

## RHIC II: Dedicated Drell Yan Experiment ? 

**BRAHMS IP**
**100 % trans-**
**verse spin**

**RHIC II: Dedicated Drell Yan Experiment ? **

_**Large acceptance Drell Yan experiment:**_
**  ****(1) 100 % Transverse Spin                        ****x 4**
**  ****(2) Large acceptance -3<****η****<+3                  ****x 8**
**  ****(3) Electron cooling                                    ****x 2.5**
**  ****(4) Mini-quads                                            ****x 4**
**                                                                  ****~300**
**Physics: Sivers-, Transversity-, **
**              ****Boer-Mulder-distributions**
**              ****in Drell Yan lepton pair **
**              ****production at RHIC.**

**Relative gain in ****∫Ldt**
**Compared to PHENIX**

## Sivers-Asymmetries, AT in Drell Yan (J. Collins et al.)

**Large Acceptance**
**DY experiment**
**With ****∫Ldt=****1250 pb****-1**

**A****T**

***Q=4GeV***

***Q=20GeV***

***Q=4GeV***

***Q=20GeV***

**A****T**

**Precision measurement of Sivers distributions ?**

## Transversity?

- ATT for Drell Yan with dedicated DY detector

- coarse estimate for 1250pb-1 of running
- for large acceptance DY-E, “RHIC II ∫Ldt”
- and 5-10% higher polarization. The estimate
- was based on Martin, Schaefer, Stratmann,
- Vogelsang, Phys.Rev.D57:3084-3090,1998.

- Drell Yan  large acceptance
- detector for Drell Yan

## Summary

- Future running of polarized protons at RHIC will lead to data samples
- a factor 100 larger then the present sample. Assuming a polarization of
- P=0.7 this will make it possible to increase the figure of merit by more
- Than two orders of magnitude for longitudinal and transverse spin
- measurements.
- In combination with detector upgrades in STAR and PHENIX this
- enables a rigorous transverse spin program
- Precision measurements of asymmetries in Collins- and
-       Interference-Fragmentation to map out quark transversity distributions.
- Access to direct photons
- Measurement of the Sivers function in Drell Yan