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HIGHLIGHTS FROM THE COMPASS EXPERIMENT @ CERN F. Bradamante University of Trieste and INFN HIGHLIGHTS FROM THE COMPASS EXPERIMENT @ CERN F. Bradamante University of Trieste and INFN Trieste on behalf of the Collaboration Sixth International Conference on Perspectives in Hadronic Physics Trieste, May 16, 2008

COmmon Muon and Proton Apparatus for Structure and Spectroscopy NA 58 Czech Republic, Finland, COmmon Muon and Proton Apparatus for Structure and Spectroscopy NA 58 Czech Republic, Finland, France, Germany, India, Israel, Italy, Japan, Poland, Portugal, Russia Bielefeld, Bochum, Bonn, Burdwan, Calcutta, CERN, Dubna, Erlangen, Freiburg, Heidelberg, Helsinki, Lisbon, Mainz, Miyazaky, Moscow, Munich, Nagoya, Prague, Protvino, Saclay, Tel Aviv, Torino, Trieste, Warsaw 28 Institutes, ~230 physicists F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

COMPASS § experiment: thought of in April ’ 94 Nov. ‘ 94 Trento workshop COMPASS § experiment: thought of in April ’ 94 Nov. ‘ 94 Trento workshop Trieste workshop @ICTP Lo. I encouraged March ’ 95 June ‘ 95 SPSLC in Cogne Proposal recommended approved by RB March ’ 96 Sept. ’ 96 Feb. ‘ 97 as NA 58 Technical run 2000 Commissioning 2001 § since 2002 taking data with a new spectrometer with outstanding performances § merging of two programmes: F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics HMC (muon beam) CHEOPS (hadron beam)

Physics program of COMPASS • Experiments with muon beam • Experiments with hadron beams Physics program of COMPASS • Experiments with muon beam • Experiments with hadron beams • ΔG/G • Pion and Kaon polarizabilities • g 1 • Diffractive production of exotic states • Transverse spin effects • Flavor decomposition of spin distribution functions • Vector meson production • Spin transfer in Λ-hyperon production F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics • Search for glueballs • Light meson spectroscopy • Production of double charmed baryons

longitudinally polarised muon beam longitudinally or transversely polarised target calorimetry particle identification luminosity: ~5. longitudinally polarised muon beam longitudinally or transversely polarised target calorimetry particle identification luminosity: ~5. 1032 cm-2 s-1 beam intensity: 2. 108 m+/spill (4. 8 s/16. 2 s) beam momentum: 160 Ge. V/c LHC SPS N F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

The Spectrometer for the Muon Programme Trigger-hodoscopes μ Filter ECal & HCal 50 SM The Spectrometer for the Muon Programme Trigger-hodoscopes μ Filter ECal & HCal 50 SM 2 m RICH SM 1 6 Li. D MWPC Straws Target μ V Ge 0 16 Gems Drift chambers Micromegas Sci. Fi Silicon F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics TWO STAGE SPECTROMETER: Polarized beam and target SAT, LAT, PID 0. 003 < x < 0. 5 10 -3 < Q 2 < 10 Ge. V 2

WHERE ARE WE ? • in 2002, 2003, 2004, 2006 and 2007 COMPASS has WHERE ARE WE ? • in 2002, 2003, 2004, 2006 and 2007 COMPASS has taken data in the muon program configuration 160 Ge. V, polarized m beam 2002 -2006 6 Li. D polarized target (~polarized deuterons) 2007 NH 3 polarized target (~polarized protons) 2000 TB ~ 5· 1010 events • pilot run in 2004 for hadron program • 2008: hadron beam at 190 Ge. V for diffractive and central production physics results 1. DG/G 2. DS 3. Transversity 4. Cahn asymmetry 5. Pentaquark 6. Exclusive ρ0 7. Λ physics F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics 1. pion polarizability 2. PWA in diffractive scattering

THE COMPASS MUON PROGRAM TWO CLASSES OF PHENOMENA: • LONGITUDINAL SPIN CASE • TRANSVERSE THE COMPASS MUON PROGRAM TWO CLASSES OF PHENOMENA: • LONGITUDINAL SPIN CASE • TRANSVERSE SPIN CASE F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

LONGITUDINAL SPIN CASE: the beginning EMC 1988 G 1 p = 0. 123 0. LONGITUDINAL SPIN CASE: the beginning EMC 1988 G 1 p = 0. 123 0. 019 DS = 0. 12 0. 17 SPIN CRISIS F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

LONGITUDINAL SPIN CASE from polarised lepton – polarised nucleon DIS with and first moments: LONGITUDINAL SPIN CASE from polarised lepton – polarised nucleon DIS with and first moments: from measurement of EMC in 1988 and using complementary information from neutron and hyperon β–decay one obtained at variance with naïve expectation since necessity for measuring SMC, SLAC, HERMES and in SIDIS F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics in SIDIS SMC, HERMES, COMPASS

LONGITUDINAL SPIN CASE physics results ΔG/G F. Bradamante, 6 th International Confrence on Perspectives LONGITUDINAL SPIN CASE physics results ΔG/G F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

MEASUREMENTS OF THE GLUON POLARIZATION FOUR LINES OF ATTACK: 1. Double spin asymmetry of MEASUREMENTS OF THE GLUON POLARIZATION FOUR LINES OF ATTACK: 1. Double spin asymmetry of the OPEN CHARM cross-section in high energy µD scattering 2. Double spin asymmetry of the HIGH-pt HADRON PAIRS in high energy µD DIS (Q 2 > 1 Ge. V 2) 3. Double spin asymmetry of the high-pt hadron pairs in high energy µD scattering (Q 2 < 1 Ge. V 2) 4. Measurement of g 1 of the deuteron and QCD fit of all the world data F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

DG/G at COMPASS Photon Gluon Fusion q = c cross section difference in charmed DG/G at COMPASS Photon Gluon Fusion q = c cross section difference in charmed meson production → theory well understood → experiment challenging N F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics q = u, d, s cross section difference in 2+1 jet production in COMPASS: events with 2 hadrons with high-pt → experiment easy → theory more difficult

ΔG/G from Open Charm F. Bradamante, 6 th International Confrence on Perspectives in Hadronic ΔG/G from Open Charm F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

D mass spectra D 0 → K π n. D* = 8675 n. D D mass spectra D 0 → K π n. D* = 8675 n. D 0 = 37398 D 0 → K π π 0 APS, 13 April 2008 G. K. Mallot F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics 15

DG/G from open charm 2002 – 2006 data D 0 + D* ΔG/G = DG/G from open charm 2002 – 2006 data D 0 + D* ΔG/G = -0. 49 ± 0. 27 (stat) ± 0. 11 (syst) @ ~ 0. 11, < 2> ~ 13 (Ge. V/c)2 preliminary F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics 16

ΔG/G from High-pt hadron pairs F. Bradamante, 6 th International Confrence on Perspectives in ΔG/G from High-pt hadron pairs F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

ΔG/G from High-pt hadrons, Q 2 > 1 (Ge. V/c)2 PGF and background PGF ΔG/G from High-pt hadrons, Q 2 > 1 (Ge. V/c)2 PGF and background PGF LO DIS F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics QCDCompton

ΔG/G from High-pt hadrons, Q 2 > 1 (Ge. V/c)2 2002 – 2004 data: ΔG/G from High-pt hadrons, Q 2 > 1 (Ge. V/c)2 2002 – 2004 data: High p. T, Q 2 > 1 Ge. V/c 2 ΔG/G = 0. 08 ± 0. 10 (stat) ± 0. 05(syst) @ = 0. 082 (range: 0. 055 – 0. 123), 2 ~ 3 (Ge. V/c)2 preliminary F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

ΔG/G from High-pt hadrons PGF low Q 2 resolved photon all Q 2 LO ΔG/G from High-pt hadrons PGF low Q 2 resolved photon all Q 2 LO DIS QCDCompton F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

ΔG/G from High-pt hadrons, Q 2 < 1 (Ge. V/c)2 2002 – 2004 data: ΔG/G from High-pt hadrons, Q 2 < 1 (Ge. V/c)2 2002 – 2004 data: High p. T, Q 2 < 1 Ge. V/c 2 ΔG/G = 0. 016 ± 0. 058 (stat) ± 0. 055 (syst) @ = 0. 085, 2 = 3 Ge. V 2 preliminary F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Gluon Polarization COMPASS preliminary results high-p. T pairs, Q 2>1 Ge. V 2 : Gluon Polarization COMPASS preliminary results high-p. T pairs, Q 2>1 Ge. V 2 : 2002– 2004 ΔG/G = 0. 08 ± 0. 10 (stat) ± 0. 05(syst) @ = 0. 082 (range: 0. 055 – 0. 123), 2 ~ 3 (Ge. V/c)2 high-pt pairs, Q 2< 1 Ge. V 2 : 2002– 2004 ΔG/G = 0. 016 ± 0. 058 (stat) ± 0. 055 (syst) @ = 0. 085, 2 = 3 Ge. V 2 open charm: 2002– 2006 ΔG/G = -0. 49 ± 0. 27 (stat) ± 0. 11 (syst) @ ~ 0. 11, < 2> ~ 13 (Ge. V/c)2 F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Summary of results new highp. T point new charm point G. K. Mallot F. Summary of results new highp. T point new charm point G. K. Mallot F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

g 1 d F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics g 1 d F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

g 1 of the deuteron (2002 -2003) Phys Lett B 612 (2005) 154 • g 1 of the deuteron (2002 -2003) Phys Lett B 612 (2005) 154 • most precise measurement for 0. 004 < x < 0. 03 • new NLO QCD fit, precision of a 0 improves factor 2 (Q 2 = 4 Ge. V 2) F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

CONCLUSION from ΔG MEASUREMENTS: ΔG SMALL more precise measurements will come soon COMPASS 2006 CONCLUSION from ΔG MEASUREMENTS: ΔG SMALL more precise measurements will come soon COMPASS 2006 RHIC RUN 6 …. interest in orbital angular momentum GPD’s Ji’s SUM RULE F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

more on LONGITUDINAL SPIN CASE MEASUREMENT OF VALENCE QUARK POLARISATION F. Bradamante, 6 th more on LONGITUDINAL SPIN CASE MEASUREMENT OF VALENCE QUARK POLARISATION F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

valence quark polarisation hadron asymmetries F. Bradamante, 6 th International Confrence on Perspectives in valence quark polarisation hadron asymmetries F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

valence quark polarisation comparison with other experiments F. Bradamante, 6 th International Confrence on valence quark polarisation comparison with other experiments F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

The Transverse Spin Case F. Bradamante, 6 th International Confrence on Perspectives in Hadronic The Transverse Spin Case F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Transverse Spin case Large effects observed in hadronic interactions F. Bradamante, 6 th International Transverse Spin case Large effects observed in hadronic interactions F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Transverse Spin case Large effects observed in hadronic interactions Theoretical developments: at leading order Transverse Spin case Large effects observed in hadronic interactions Theoretical developments: at leading order a third PDF is necessary for a complete description of the structure of the nucleon q(x) DTq(x) • DTq(x) being chiral-odd, it can be measured only in conjunction Collins function with another chiral-odd partner: DY SIDIS measurable in e+e- hadrons • relevance of transverse momentum dependent (TMD) PDF and FF Sivers function Many Workshops in recent years on Transverse Momentum, spin, and position distributions of partons in hadrons F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Transversity – single hadron -1 Collins and Sivers angles C = h - S’ Transversity – single hadron -1 Collins and Sivers angles C = h - S’ S = h - S S ’ azimuthal angle of spin vector of fragmenting quark ( S’’ = p - S) h azimuthal angle of hadron momentum F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Transversity – single hadron - 2 first measurements of transverse spin asymmetries in DIS Transversity – single hadron - 2 first measurements of transverse spin asymmetries in DIS of high energy muons on a transversely polarized deuteron target published single hadron asymmetries from 2002 -2004 runs • Collins: related to transverse quark distributions Phys Rev Lett 94 (2005) 202002 • Sivers: related to intrinsic k. T Nucl Phys B 765 (2007) 31 F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Collins asymmetry for pions and kaons preliminary 2002 -2004 data proton (virtual photon asymm) Collins asymmetry for pions and kaons preliminary 2002 -2004 data proton (virtual photon asymm) (lepton beam 2002 -05 DIS 07) final CERN-PH-EP/2008 -002 hep-ex/0802. 2160 (PRL) 2003 -2004 data deuteron (virtual photon asymm) COMPASS sign convention F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Independent Measurement of the Collins FF measurable in e+e– annihilation • first attempts to Independent Measurement of the Collins FF measurable in e+e– annihilation • first attempts to measured it from the correlation between the azimuthal angles of p‘s from e+e– annihilation using LEP data last years: great news from BELLE the Collins FF is being measured in e+e– annihilation, and it is different from zero! measurement of the correlation between the azimuthal angles of ‘s in the near jet and in the far jet from e+e– annihilation • 547 fb-1 charm corrected data sample, • UL and UC double ratios F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Collins asymmetries: SUMMARY The facts: • HERMES has measured on a proton target non-zero Collins asymmetries: SUMMARY The facts: • HERMES has measured on a proton target non-zero Collins asymmetries for π+ and π • COMPASS has measured on a deuteron target Collins asymmetries compatible with zero • BELLE has produced the first results on Collins FF Conclusion: • Collins mechanism is a real phenomenon • universality of Collins FF • transversity can be measured in SIDIS Present picture • Collins: DTu ~ - DTd DT 0 D(fav. ) ~ - DT 0 D(unfav) To extract TMD DF and FF GLOBAL ANALISYS are necessary F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

HERMES, COMPASS, BELLE F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics HERMES, COMPASS, BELLE F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Sivers asymmetry for pions and kaons preliminary 2002 -2005 data proton (DIS 07) CERN-PH-EP/2008 Sivers asymmetry for pions and kaons preliminary 2002 -2005 data proton (DIS 07) CERN-PH-EP/2008 -002 hep-ex/0802. 2160 (PRL) 2003 -2004 data deuteron F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Sivers asymmetry the measured asymmetry on deuteron compatible with zero has been interpreted as Sivers asymmetry the measured asymmetry on deuteron compatible with zero has been interpreted as Evidence for the Absence of Gluon Orbital Angular Momentum in the Nucleon S. J. Brodsky and S. Gardner, PLB 643 (2006) 22 F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

SUMMARY AND OUTLOOK • a technically challenging new experiment is IN OPERATION SINCE 2002 SUMMARY AND OUTLOOK • a technically challenging new experiment is IN OPERATION SINCE 2002 “LHC” technologies detectors read-out data handling • a privileged situation at CERN • MANY PHYSICS RESULTS have been produced MANY MORE IN THE PIPE-LINE • COMPASS is foreseen to run up to the end of the present mid-term plan of CERN (2010) BIG DISCOVERY POTENTIAL • with some upgrade COMPASS might be an interesting option even in the second decade of this century F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

• SPARE SLIDES F. Bradamante, 6 th International Confrence on Perspectives in Hadronic • SPARE SLIDES F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Transversity: two hadrons F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics Transversity: two hadrons F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics -1

Transversity: two hadrons -2 all +/- combinations • precise measurement of few % • Transversity: two hadrons -2 all +/- combinations • precise measurement of few % • systematics seems well under control • also compatible with zero • interesting to see proton in 2006 F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Exclusive ρ0 production F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics Exclusive ρ0 production F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Exclusive ρ0 production (2002 data) F. Bradamante, 6 th International Confrence on Perspectives in Exclusive ρ0 production (2002 data) F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics -1

Exclusive ρ0 production - 2 ANGULAR DISTRIBUTIONS 2 0. 01 2. 0 < 0. Exclusive ρ0 production - 2 ANGULAR DISTRIBUTIONS 2 0. 01 2. 0 < 0. 01<

Exclusive ρ0 production measurement 0. 01 < Q² < 0. 05 < Q² < Exclusive ρ0 production measurement 0. 01 < Q² < 0. 05 < Q² < -3 0. 3 < Q² < 0. 6 < Q² < 2. 0 of r 04 00 distribution : Spin density matrix element: Tλρ λγ are helicity amplitudes meson photon F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics 2002 < Q² < 10 Ge. V 2

Exclusive ρ0 production measurement 0. 01 < Q² < 0. 05 < Q² < Exclusive ρ0 production measurement 0. 01 < Q² < 0. 05 < Q² < 04 of r 1 -1 and Im r 3 1 -1 distribution : beam polarisation Spin density matrix element: if SCHC holds weak violation F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics - 4 0. 3 < Q² < 0. 6 < Q² < 2. 0 < Q² < 10 Ge. V 2

Pentaquark search F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics Pentaquark search F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Φ(1860) Pentaquark search -1 motivated by NA 49 report of pentaquark candidate • COMPASS Φ(1860) Pentaquark search -1 motivated by NA 49 report of pentaquark candidate • COMPASS has large sample of the double-strange Ξ – + baryon (18000 Ξ , 11000 Ξ ) from 2002 -2003 data – – • search for Ξ π resonance Φ(1860) –– – – – → Ξ π → Λπ π → p π π π F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics – –

Φ(1860) Pentaquark search -2 Eur Phys J C 41 (2005) 469 Ξ(1530)0 compare to Φ(1860) Pentaquark search -2 Eur Phys J C 41 (2005) 469 Ξ(1530)0 compare to yields – + • opposite-sign pairs: Ξ(1530)0 → Ξ π , 1700 and 920 evts • like-sign pairs: evts <79 and <89 at 99% CL (expected ~400) F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Transversity: Λ polarization 2002 -2003 data F. Bradamante, 6 th International Confrence on Perspectives Transversity: Λ polarization 2002 -2003 data F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Longitudinal polarization of Λ and antiΛ in DIS F. Bradamante, 6 th International Confrence Longitudinal polarization of Λ and antiΛ in DIS F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Λ POLARIZATION (2002 data) -1 ’+ V 1 Event selection + p V 2 Λ POLARIZATION (2002 data) -1 ’+ V 1 Event selection + p V 2 q N( ) 750 650 8087 649 HERMES 1996 -2000 10568 1687 COMPASS 2002 7919 5062 COMPASS 2003 34789 20651 E 665 NOMAD F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Λ POLARIZATION 2002 data F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Λ POLARIZATION 2002 data F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics

Λ POLARIZATION 2002 data F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Λ POLARIZATION 2002 data F. Bradamante, 6 th International Confrence on Perspectives in Hadronic Physics