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Workshop on Hadron Structure at J-PARC, November 30 - December 2, 2005

This workshop focused on the possibility of direct extraction of transversity from polarized Drell-Yan measurements in the COMPASS experiment. The workshop highlighted the requirements to the apparatus and the potential of Drell-Yan for accessing transversity.

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Workshop on Hadron Structure at J-PARC, November 30 - December 2, 2005

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  1. Workshop on Hadron Structure at J-PARC, November 30 - December 2, 2005             KEK, Tsukuba, Ibaraki, Japan Possibility of direct extraction of the transversitiy from polarized Drell-Yan measurement in COMPASS T.Iwata ( Yamagata University) on behalf of COMPASS collaboration Transversity Drell-Yan for transverstiy transverse momentum dependent PDFs polarized Drell-Yan idea of the Drell-Yan measurement in COMPASS requirements to the apparatus summary

  2. Transversity ・Nucleon quark structure completely described by 3 distribution functions ( at twist 2 level) longitudinal • momentum distribution • helicity distribution • transversity distribution transverse • transversity hasnever • been determined • in experiments • accessible in SI-DIS with transversely polarized targets • data available from HERMES, COMPASS, J-Lab • need polarized fragmentation functions ( not well known) • study ongoing in Belle T.Iwata @ Workshop on Hadron Structure at J-PARC, Nov. 30 – Dec. 2, 2005, KEK

  3. Drell-Yan for Transversity Drell-Yan is alternative way to access transversity Advantage: no need of any fragmention functions • double polarized Drell-Yan allows direct extraction of transverstiy Possible GSI: But, a big challenge experimentally T.Iwata @ Workshop on Hadron Structure at J-PARC, Nov. 30 – Dec. 2, 2005, KEK

  4. Single polarized Drell-Yan • single polarized Drell-Yan less difficut experimentally COMPASS setup COMMON Apparatus for muon & hadron programs • Unique environment of COMPASS • polarized target • hadron beam • high rate trackers • muon identification Polarized target long. & trans. pol • Two stages • RICH • High rate trackers • Ecal, Hcal • Muon filters Beam: muon & hadrons(p/p) Transversity accompanied with T-odd PDF ( one of the transvese momentum dependent PDFs) A.Sissakian et al., Phys. Rev. D72, 054027 (2005) T.Iwata @ Workshop on Hadron Structure at J-PARC, Nov. 30 – Dec. 2, 2005, KEK

  5. Transverse momentum dependent PDFs Nucleon unpol. long. pol. trans. pol. number density Sivers unpol. Nucleon T-odd Parton helicity long. pol. Quark transversity Boer-Mulders survive after integration over kT trans. pol. T-odd T.Iwata @ Workshop on Hadron Structure at J-PARC, Nov. 30 – Dec. 2, 2005, KEK

  6. Unpolarized-Drell-Yan How to extract transversity in DY measurement? The ider is based on A.Sissakian et al., Phys. Rev. D72, 054027 (2005) unpolarized Drell-Yan case qT weighted angular distribution (qT :transvese momentumof virtual photon) lepton pair CM frame V.Barone et al., Phys. Rep. 359 (2002)1-168 T.Iwata @ Workshop on Hadron Structure at J-PARC, Nov. 30 – Dec. 2, 2005, KEK

  7. Coefficient of COS2f term Boer-Mulder PDF(T-odd) for anti-q in p Boer-Mulder PDF(T-odd) for q in proton 1st moment of the PDFs: number densities (well known) T.Iwata @ Workshop on Hadron Structure at J-PARC, Nov. 30 – Dec. 2, 2005, KEK

  8. Single Spin Asymmetry single polarized Drell-Yan case qT weighted single spin asymmetryfor : azimuthal angle of the target spin vector : target spin vector Boer-Mulder PDF(T-odd) for anti-q in p transversity T.Iwata @ Workshop on Hadron Structure at J-PARC, Nov. 30 – Dec. 2, 2005, KEK

  9. Simplidied equations 3 3 2 1 1 1 neglects-quark, sea quark in proton, and d-quark contributions (d-quark originally suppressed due to its charge) expressions with only u-quark PDFs given from Boer-Mulder PDF(T-odd) for anti-u in p transversity known transversity known to be extracted T.Iwata @ Workshop on Hadron Structure at J-PARC, Nov. 30 – Dec. 2, 2005, KEK

  10. Extraction in single exp. I Additonal assumption based on Boer’s model Phys.Rev. D60, 014012 (1999) E615 @ Fermilab Phys. Rev. D39 (1989) 92 anomalously large cos2f dependence observed Naive Drell-Yan thery predicts pQCD (LO,NLO) not explained it Boer’s Model explained it with transverse momentum dependent PDF (at LO) T.Iwata @ Workshop on Hadron Structure at J-PARC, Nov. 30 – Dec. 2, 2005, KEK

  11. Extraction in single exp. II 2 2 1 1 With the assumption, the observables are rewritten only with the PDFs for proton unknown PDFs Boer-Mulder PDF (T-odd) for proton at the point transversity T.Iwata @ Workshop on Hadron Structure at J-PARC, Nov. 30 – Dec. 2, 2005, KEK

  12. Counting rate in COMPASS • Beam: 100 GeV p- • Target: 60 g/cm2 NH3 • Luminosity: • Cross section value: • Acceptance : • Expected rate for DY: • Thus 0.08 events/spill (4000 spills/day)  320 events/day • Total statistics: (SPS eff=80%) 120 days  30k events/year Very preliminary! T.Iwata @ Workshop on Hadron Structure at J-PARC, Nov. 30 – Dec. 2, 2005, KEK

  13. Comparison of running conditions current condition withm beam Drell-Yan with p beam T.Iwata @ Workshop on Hadron Structure at J-PARC, Nov. 30 – Dec. 2, 2005, KEK

  14. Requirements to the apparatus • Spectrometer: • high rate capability required ( for trackers near the target) • upgrading SciFi, GEM, Micromegas • no need of complete particle ID(only muon ID with muon filters) • Polarized target: •  heat load increase by x ~ 10 ( 0.5mW, ~ 2mW/spill) • runing in frozen spinmode( for transverse polarization) • better cooling efficiency needed to maintain its polarization T.Iwata @ Workshop on Hadron Structure at J-PARC, Nov. 30 – Dec. 2, 2005, KEK

  15. Improvements of PT The dilution refrigerator can manage the heat load (sufficient cooling power) small beads or thin sheet larger surface area frozen spin mode Maximum beam intensity vs. bead diameter DNP mode N.Doshita et al., NIM A 526 (2004) 138-143 Problem: removing heat from the material NH3 in SMC, (2006 COMPASS) heat from target bead  bottle neck: Kapitza resistance Relaxation time(NH3) : T1=400 hours @ 60mK, 0.4T, T.Iwata @ Workshop on Hadron Structure at J-PARC, Nov. 30 – Dec. 2, 2005, KEK

  16. Summary • Drell-Yan process is a powerful tool to study the • transverstiy and the accompanying T-odd kt dependent • PDFs. • COMPASS offers unique environment for the single plarized • Drell-Yan measurement. • The design of the measurment is underway in COMPASS • collaboration. • Requirements to the apparatus were shown in this talk. T.Iwata @ Workshop on Hadron Structure at J-PARC, Nov. 30 – Dec. 2, 2005, KEK

  17. Backup slides

  18. Boer’s Model Phys.Rev. D60, 014012 (1999)

  19. given from

  20. Accessible kinematicsin COMPASS

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