COMPASS PLANS Stephane Platchkov Institut de Recherche sur les lois Fondamentales de l’Univers CEA/IRFU, Saclay, France (for the COMPASS Collaboration) EIC workshop Stony Brook, June 24-27, 2014

COMPASS – a fixed target experiment A very versatile setup Several beams available: µ+, µ-, h+, h-, e- => Several physics goals Energy: 100 – 200 GeV Intensity: up to 109 /spill Large acceptance, PID detectors Several particles in the final state Large (1.2 m) polarized target 50 m “Minor” changes to the setup – switch between various physics programs S. Platchkov EIC 2014

COMPASS – a fixed target experiment A very versatile setup Several beams available: µ+, µ-, h+, h-, e- => Several physics goals Measurements with muon beams Gluon polarization Spin-flavor decomposition Transversity Transv. Mom. Distributions Measurements with hadron beams Pion polarizability Light meson spectroscopy Baryon spectroscopy Search for hybrids COMPASS - I (2002 – 2011) COMPASS - II (2012, 2015 – 2017/2018) DVCS and HEMP Unpolarized SIDIS and TMDs Drell-Yan studies Pion and Kaon polarizabilities S. Platchkov EIC 2014

Nucleon structure studies – physics goals from Bacchetta from Bacchetta PDF (x) TMD (x,kT) GPD (x,bT) Drell-Yan S. Platchkov EIC 2014

DVCS and HEMP studies S. Platchkov EIC 2014

DVCS characteristics in COMPASS Beams 100 – 200 GeV Beam polarization: ~80% Both m+ and m- beams x domain: ≈ 0.01 – 0.1 Q2 domain: 1 to 10 (GeV/c)2 Luminosity: 1032 cm-2s-1 (with a 2.5 m long LH2 target) + EIC Detect both outgoing photon and recoiling proton S. Platchkov EIC 2014

DVCS and BH cross section for µ+ and µ- Cross section for µp -> µpγ : COMPASS beams: opposite charge/spin Charge-and-Spin Sum: Charge-and-Spin Difference small for COMPASS DVCS BH Access both Re(H) and Im(H) by measuring the Sum and the Difference S. Platchkov EIC 2014

DVCS – SUM of m+ and m- cross sections Expected statistics in 2 x 140 days of data taking Goal: transverse size of the nucleon as a function of xB - Nucleon “tomography” - S. Platchkov EIC 2014

Beam Charge and Spin Difference Expected statistics in 2 x 140 days of data taking Kroll, Moutarde, Sabatié, EPJC 73(2013)2278 S. Platchkov EIC 2014

DVCS – the COMPASS xB regions – SIMULATION 0.005 < xB <0.01 0.01 < xB < 0.03 xB > 0.03 DVCS BH DVCS BH Large relative amplitude variation as a function of x EIC 2014 S. Platchkov

DVCS – the COMPASS xB regions – REAL DATA Test run – 4 days with a 40 cm long H2 target 2009 data 278 134 54 DVCS BH dominance Interference DVCS dominance Successful feasibility measurement S. Platchkov EIC 2014

DVCS run – main new equipment ECAL0 ECAL1 ECAL2 50 m 4.0 m longTime-Of-Flight detector: 24 inner and 24 outer slabs 2x2 m2 electromagnetic calorimeter, ECAL0 2.5 m long LH target S. Platchkov EIC 2014

2012 DVCS setup – 4 weeks data taking ECAL2 Partially ready ECAL0 ECAL1 Full scale recoil proton detector Liquid H2 target S. Platchkov EIC 2014

Transverse size of the nucleon Test data taking in 2012 – 4 weeks 2012 data: expected uncertainty Data analysis is underway S. Platchkov EIC 2014

Semi-inclusive unpolarized DIS Features Pure hydrogen target, 2.4 m long High-performance particle identification for p+,p-,p0,K+,K-,K0 etc… Measurements of: Multiplicities Input to global FF analysis Strange quark pPDF down to x=0.004 Phys. Rev. D 89 (2014) 097101 1 week of beam will s(x) continue to raise? S. Platchkov EIC 2014

Beyond GPD H Hard Exclusive Meson production Vector mesons: sensitive to H, E allows for flavour separation Present studies at COMPASS : Transversely polarized target No recoil proton detection (From transversity data: 2007/2010) First example: exclusive r production S. Platchkov EIC 2014

Exclusive r0 production Measurement: μ + p  μ’ + 0 + p  +- COMPASS: PLB 731 (2014) 19 NPB 865 (2012) 1 First possible indication for a non-vanishing HT Access to different E and H combinations Analysis of w ongoing S. Platchkov EIC 2014

Distant future (beyond 2018) DVCS and HEMP on a transversely polarized target 2 years of data, NH3 target, 160 GeV, global efficiency ~10% Main challenge: development of dedicated superconducting magnet Planned proposal/addendum S. Platchkov EIC 2014

Overview of past/planned GPD experiments S. Platchkov EIC 2014

Drell-Yan studies S. Platchkov EIC 2014

Polarized Drell-Yan measurements Drell and Yan, PRL 25 (1970), 316, 902. . COMPASS setup advantages Beam energy: 100 – 200 GeV Hadron (pion) beam Transversely polarized NH3 target Large muon angular acceptance With a negative pion beam: u/u annihilation COMPASS acceptance (MC simulation) Dominated by valence quarks (x ≥ 0.1) COMPASS is an ideal place for DY studies S. Platchkov EIC 2014

DY (polarized) cross section expansion Tung-Mow Yan (SLAC, 1998): “The process (1970) has been so well understood that it has become a powerful tool for precision measurements and new physics” Full formalism for two spin ½ hadrons COMPASS: access 4 TMDs: Boer-Mulders, Sivers, Pretzelosity, Transversity Access 4 TMDs – asymmetry modulations: Arnold, Metz and Schlegel, Phys. Rev. D79 (2009) 034005. Boer-Mulders Sivers Pretzelosity Transversity Worm-Gear All four TMDs are also measured in SIDIS S. Platchkov EIC 2014

TMDs in Drell-Yan and SIDIS SIDIS vs TMD SIDIS: TMD and FF Drell-Yan: two TMDs Factorization TMDs (unlike PDFs) can be process dependent (“non-universality”) Opposite sign in SIDIS and DY processes: Collins, Soper, Sterman, Adv. Ser. High En Phys. 5, 1988. Crucial test of the QCD factorization approach S. Platchkov EIC 2014

Sivers asymmetry (SIDIS) Compass data on a proton target pions kaons COMPASS data: PLB 692 (2010) 240 PLB 717 (2012) 383 + preliminary Hermes data: PRL 103 (2009) 152002 S. Platchkov EIC 2014

Drell-Yan acceptances (COMPASS vs E615) 0.04 E615 (1989) 0.4 COMPASS (2014) An order of magnitude improvement S. Platchkov EIC 2014

SIDIS vs Drell-Yan (x - Q2) regions Kinematical overlap between SIDIS and Drell-Yan S. Platchkov EIC 2014

COMPASS Drell-Yan setup Upgrade of the spectrometer Beam telescope (Sci-Fi) Thick hadron absorber/beam dump Vertex detector Polarized target moved 2.2 m upstream S. Platchkov EIC 2014

COMPASS Drell-Yan setup Small cross sections – high intensity h beam (~109/spill of 10 sec) Possible use of thin nuclear targets (inside the absorber) pion beam 190 GeV Polarized Target Hadron absorber: Tungsten, Alumina and Stainless steel Nominal COMPASS setup (minor modifications) Dimuon trigger system S. Platchkov EIC 2014

Drell-Yan – test data taking Test setup (3 days in 2009) 190 GeV negative pion beam, I ≤ 1.5x107/s (instead of 108/s) “poor-man” hadron absorber ( concrete and steel) two polyethylene target cells preliminary DY trigger Results Count rate confirmed Mass resolution as expected Good vertex resolution Low background at high masses S. Platchkov EIC 2014

Expected statistical accuracy Assumptions: Ibeam = 108p/s, L = 2.3x1033, P=90%, f = 0.22, t = 140 days, spill length = 10 s, every 34 s ~ 2000 DY events/day in the mass region 4 < Mµµ < 9 GeV/c2 J/Ψ cross section: about 50 times larger Boer-Mulders Sivers Pretzelosity Transversity S. Platchkov EIC 2014

Polarized Drell-Yan – expected results Sivers Boer-Mulders 140 days of data 6.108 pions/spill 2 x 55 cm NH3 target 4 < Mmm< 9 GeV Pretzelosity Transversity S. Platchkov EIC 2014

Further Drell-Yan studies Dutta et al., PRC83:042201,2011 DY on nuclear targets flavour-dependent EMC effect First glimpse from the 2015 data S. Platchkov EIC 2014

Drell-Yan: further possibilities Medium term DY on nuclear targets Flavour dependent EMC, Violation of the Lam-Tung relation Polarized deuteron ( 6LiD) target Flavour separated TMDs Long term RF separated K- and p beams Recall: at 190 GeV: p-/K-/p = 96.5%/2.5%/1% Aim at 1 to 2 orders of magnitude improvement for K- and p S. Platchkov EIC 2014

COMPASS OUTLOOK 2014 2015 End 2015, beg. 2016 2016/2017 Preparation for DY run Refurbished PT magnet, PT installation, hadron absorber 2 months of data taking (October-December) 2015 Drell - Yan data taking (1 “year” ≈ 140 days) End 2015, beg. 2016 Removal of PT, Installation of LH target, CAMERA, ECAL0 2016/2017 DVCS data taking (2 “years” ≈ 2x140 days) 2018 and beyond Long Shutdown 2 Extensions of DY and DVCS programs (definition underway) S. Platchkov EIC 2014

The End S. Platchkov EIC 2014

Exclusive r0 production Measurement: μ + p  μ’ + 0 + p  +- 5 single-spin (UT) asymmetries 3 double-spin (LT) asymmetries Curves: Goloskokov and Kroll, EPJ C74(2014)2725 Data: Compass, PLB, 731(2014)19. S. Platchkov EIC 2014

Boer-Mulders asymmetry (SIDIS) Compass data on deuteron (6LiD) Significantly different from zero Larger for negative hadrons Dependence on all three variables: x, z, pT COMPASS preprint, hep-ex:1401.6284 also HERMES: PRD 87 (2013)012010. S. Platchkov EIC 2014