HADRON SPECTROSCOPY AT COMPASS -- Exotic Hadrons at COMPASS -- Takahiro Iwata Yamagata University New Frontiers in QCD, February 5, 2010 on behalf of the COMPASS Collaboration
Introduction to COMPASS Physics in Hadron Spectroscopy Diffractive dissociation to Diffractive dissociation to Central production of 4-charged-pions channels Kaonic final states: KK , KK, K Conclusion OUTLINE Takahiro Iwata New Frontiers in QCD, February 5, 2010
COMPASS Takahiro Iwata New Frontiers in QCD, February 5, 2010 NA58 experiment at CERN SPS COmmon Muon and Proton Apparatus for Structure and Spectroscopy 20 Institutes/11 counties/~230 physicists Czech Republic, Finland, France, Germany, India, Israel, Italy, Japan, Poland, Portugal and Russia Bielefeld, Bochum, Bonn, Burdwan/Calcutta, CERN, Dubna, Erlangen, Freiburg, Lisbon, Mainz, Moscow, Munich, Prage, Protvino, Saclay, Tel Aviv, Torino, Trieste, Warsaw and Yamagata
Takahiro Iwata New Frontiers in QCD, February 5, /03/2016 BEACH08 26 june N SPS LHC CERN (Suisse) CERN (France) Lake LEMAN COMPASS COMPASS at CERN Airport
PHYSICS PROGRAMS OF COMPASS Takahiro Iwata New Frontiers in QCD, February 5, 2010 Muon program pol- beam: Runs: ,06-07 Nucleon Spin Structure Gluon polarization G/G g 1 spin structure function Flavor decomposition of spin distributions Transverse spin effects Spin transfer in - hyperon production Vector meson production Hadron program hadorn-beams: Runs : 2004, Hadron spectroscopy Diffractive production Search for new exotic states, glueballs or hybrids Light meson spectroscopy Primakov scattering Polarizabilities （ Doubly charmed baryons ）
Takahiro Iwata New Frontiers in QCD, February 5, 2010 SM1 SM2 Pol. beam 160GeV/c Pol. 80% ｆ rom SPS (CERN) MuonWall E/HCAL RICH Polarized Target SciFi Silicon Micromegas GEMs Straws SDC MWPC W45 SETUP FOR MUON PROGRAM two stages spectrometer Large Angle Spectrometer (SM1) Small Angle Spectrometer (SM2) tracking, calorimetry, PID(RICH/muon-filter) High rate capability high energy beam broad kinematical range large angular acceptance An experiment with pol. muon beam and pol. target at CERN < x < < Q 2 < 10 GeV 2 NIM A 577(2007) 455
Takahiro Iwata New Frontiers in QCD, February 5, 2010 SETUP FOR HADRON PROGRAM Beam: 190 GeV positive/negative hadrons Negative: 96% -, 3.5% K -, 0.5% p-bar Positive: 75% p, 25% +, 5% K + Beam intensity: 2·10 7 /s ( 10 8 /spill, spill=4.8s, cycle=16.8s) P-id by beam Cherenkov Counter (CEDAR) Target: liquid H 2, 40 cm long (Pb in 2004 pilot run)
Takahiro Iwata New Frontiers in QCD, February 5, 2010 TARGET PART IN HADRON PROGRAM RPD(Recoil Proton Detector) Installed in 2007
PhysicsinHadronSpectroscopy Takahiro Iwata New Frontiers in QCD, February 5, 2010
Takahiro Iwata New Frontiers in QCD, February 5, 2010 PHYSICS GOALS Objectives mainly in meson spectroscopy QCD allows states which are forbidden in the quark Model Exotic states Glueballs: Hybrids : Tetraquarks : Mixing with ordinary mesons with the same quantum numbers complicated situation Exotic J PC states : non-qq states : important to find them COMPASS contributes in the low mass region
Takahiro Iwata New Frontiers in QCD, February 5, 2010 GLUEBALLS [Y. Chen et al., Phys. Rev. D 73, (2006)] Quenched L-QCD prediction Lightest glueballs: scalar tensor Experimental candidate: f 0 (1500) (Crystal Barrel, WA102) J PC = 0 ++ << ordinary J PC mixing with ordinary mesons! COMPASS
Takahiro Iwata New Frontiers in QCD, February 5, 2010 HYBRIDS Light meson sector hybrid candidate with exotics J PC =1 -+ : 1 (1400) (VES, E852, Crystal Barrel) 1 (1600) (E852, VES) still controversial... [S.U. Chung et al., PRD 65, (2002)] [A.R. Dzierba et al., PRD 73, (2006)] M(3 ) (GeV/c 2 ) Events / 0.04 GeV/c 2 20 waves 35 waves COMPASS
Takahiro Iwata New Frontiers in QCD, February 5, 2010 PRODUCTION MECHANISMS Central productionDiffractive dissociation Rapidity gap between p slow, h fast, X Beam particle looses ~10% of its energy Particles at large angles from X decays Possible source of glueballs in forward direction separate particles at very small angles Production of Isovectors study hybrid states
Takahiro Iwata New Frontiers in QCD, February 5, 2010 DiffractiveDissociationto - - + final State
Takahiro Iwata New Frontiers in QCD, February 5, 2010 IN 2004 Pilot run in 2004 ( 3 days ) 190 GeV - beam 3mm thick Pb target Diffractive dissociation from - Pomeron exchange final state (4 M events)
Takahiro Iwata New Frontiers in QCD, February 5, 2010 INVARIANT MASS OF 3 system 2004 COMPASS 450 k events 0.1<t’<1.0 GeV 2 /c 2 BNL E852 P =18 GeV/c 250 k events 0.08<t’<1.0 GeV 2 /c 2 COMPASS BNL E852 Acceptance COMPASS acceptance is flat 50-60%, independent from the mass
Takahiro Iwata New Frontiers in QCD, February 5, 2010 PARTIAL WAVE ANALYSIS Illinois/Protovino/Munich Program & BNL/Munich Program (independent cross-check) based on Isobar model Step 1. Mass-Independent PWA 40 MeV/c 2 mass bin Gottfried-Jackson frame ( z//beam ) 42 partial waves: J PC M Y L Y :isobars ( ) S, f 0 (980), (770), f 2 (1270), 3 (1690) Background wave fit in extended maximum likelihood Step 2. Mass-Dependent 2 fit fit the results of step 1 Parameterized by Breit-Wigner 6 waves + coherent background M: absolute value of the spin projection to the z axis
Takahiro Iwata New Frontiers in QCD, February 5, 2010 MAJOR WAVES
Takahiro Iwata J PC =1 - + EXOTIC WAVE Non-resonant B.G. due to Deck-effect Phys. Rev. Lett. 13, 169 (1964). 1 (1600): phase to phase to 1 ++ a 1 (1260): 1 ++ Submitted to Phys.Rev. Lett. 1 (1600): 1 -+ 2 (1670): 2 -+ 1 (1600): 1 -+ No phase motion phase motion
Takahiro Iwata New Frontiers in QCD, February 5, 2010 IN GeV/c negative hadron beam; P-id by beam line Cherenkov Counter 96% -, 3.5% K -, 0.5% p-bar 40 cm liquid hydrogen target Spectrometer upgrade before 2008 run RPD, Silicon, Pixel GEM Exclusive measurements X10 BNL E852 statistics for full 2008 data After all cuts Exclusivity cut [ GeV]
Takahiro Iwata New Frontiers in QCD, February 5, 2010 PWA FOR 2008 PWA has been started Illinois/Protovino/Munich Program. Same wave set (42 waves). No acceptance correction applied yet. Dominant waves 1 ++ total( =+) 2 ++ total( =+) 2 -+ total( =+)
DiffractiveDissociationto - 0 0 final State Takahiro Iwata New Frontiers in QCD, February 5, 2010
Takahiro Iwata New Frontiers in QCD, February 5, 2010 IN 2008 Isospin partner to - - + Consistency check Different isobars in decay chain
Takahiro Iwata New Frontiers in QCD, February 5, ST ATTEMPT OF PWA FOR PWA : Illinois/Protovino/Munich Program Isobars: No acceptance correction applied yet. Relative intensities of charged and neutral modes are consistent with the isobar decays 1 ++ a 1 (1260) 2 ++ a 2 (1280) 2 -+ f 2 2 (1670) Intensities normalized to a2
Central Production of 4-charged-pions – p – fast + - + - p) Takahiro Iwata New Frontiers in QCD, February 5, 2010
Takahiro Iwata New Frontiers in QCD, February 5, 2010 + - + - IN CP Study glueballs ( f 0 and f 2 families) – p – fast ( + - + – ) p slow -- - fast X p p slow -- -- ++ ++ Central Production( CP)
Takahiro Iwata New Frontiers in QCD, February 5, 2010 ENHANCEMENT OF CP Enhancing CP with Feynman X: WA102 (Phys.Lett.B413: ,1997) WA102 COMPASS f 0 (1450) f 2 (1900) f 1 (1285) PWA is prepared in COMPASS ’ + - + - + - ( 0 ) f + - + - + - ( 0 ) 0 ++
– p – p, – p – p, – p – p Takahiro Iwata New Frontiers in QCD, February 5, 2010
Takahiro Iwata New Frontiers in QCD, February 5, 2010 CHANNEL – p – p ( 2 ) ( 2 ) Constraint 1 with confidence level > 10% event selection Amplitude analysis with 150k events in progress Better statistics expected with calorimeter calibration(2008 data) and LASER and LED monitor (2009 data) -- exotic J pc =1 -+ 1 (1400) 1 (1400) ?
Takahiro Iwata New Frontiers in QCD, February 5, 2010 CHANNEL Hybrid ? - Fit on two mass constraint: confidence level > 10% ( for each combination) event selection 0 background rejected 3 combinations / event – p – p ( 4 ) ( 4 ) Projection
Takahiro Iwata New Frontiers in QCD, February 5, 2010 and IN CHANNEL - Amplitude analysis with 5k events for and in progress Better statistics expected with calorimeter calibration(2008 data) and LASER and LED monitor (2009 data) exotic J pc =1 -+ 1 (1400) glueball candidate f 0 (1500) Structure at 1.5GeV in 1 (1400); exotic J pc state :glueball ?
Kaonic Final States: – p K + K – – p, – p K s 0 K s 0 – p, …. Takahiro Iwata New Frontiers in QCD, February 5, 2010
Takahiro Iwata New Frontiers in QCD, February 5, 2010 KAONIC FINAL STATES Glueball candidates decaying into KK f 0 (1380),f 0 (1500): qq mixing with gg ? Hybrid candidates decaying into KK (1800): usual 3 1 S 0 or Hybrid? Accessible channels: – p K + K – – p, This talk – p K s 0 K s 0 – p, This talk – p – – + p, – p K s 0 K L 0 – p, …. same with positive charged beam
Takahiro Iwata New Frontiers in QCD, February 5, 2010 KK SUBSYSTEM Allowed J pc for different combinations of KK Neutral channels pick out the subsets K + K - identified by RICH: 10 GeV/c < P K < 30 GeV/c Cut in acceptance K + K – Ks0Ks0Ks0Ks0 Two displaced vertexes for Ks 3 charged ( + -- ) tracks One negative track identified as K - by RICH Event selection range for kaon-id. RICH
Takahiro Iwata New Frontiers in QCD, February 5, 2010 K INVARIANT MASS K s 0 - K + - Expected structures for K*(892): 1 3 S 1 K*(1410):2 3 S 1, K 0 *(1430):1 3 P 0, K 2 *(1430): 1 1 D 2 Almost background free the structures are also visible. Acceptance in the low mass region is affected by RICH threshold. contamination in P-id
Takahiro Iwata New Frontiers in QCD, February 5, 2010 KK INVARIANT MASS K + K - Ks0Ks0Ks0Ks0 Known resonances visible in both mass spectra: f 0 (1500): glueball candidate f 2 ‘(1520): 1 3 P 2
Takahiro Iwata New Frontiers in QCD, February 5, 2010 KK INVARIANT MASS K + K - - K s 0 K s 0 - Structures around 1.8 GeV and 2.2GeV
Takahiro Iwata New Frontiers in QCD, February 5, 2010 K v.s. KK in K + K - - X(2.2GeV) K *(890)+ K - / K K - X(1.8GeV) K *(890)+ K -
Takahiro Iwata New Frontiers in QCD, February 5, 2010 K v.s. KK in Ks Ks - X(2.2GeV) K *(890)+ Ks / K Ks X(1.7GeV) K *(890)+ Ks
Takahiro Iwata New Frontiers in QCD, February 5, 2010 KK v.s. KK in K + K - - X(2.2GeV) ( /a /f 0 ) + – K - X(1.8GeV) K -
Takahiro Iwata New Frontiers in QCD, February 5, 2010 m( K s 0 K s 0 )/GeV m( K s 0 K s 0 - ) /GeV Quite different form K + K - - due to allowed J PC =0 ++,2 ++,4 ++ for KsKs KK v.s. KK in K s K s - f 0 (1380) f 0 (1500) a 0 (980)/f 0 (980)
Takahiro Iwata New Frontiers in QCD, February 5, 2010 NEXT STEPS IN KK CHANNELS Mass-independent PWA to be performed Enhancing central production for KK system Ks0Ks0Ks0Ks0 Ks0Ks0Ks0Ks0 FASTEST- Selection
Takahiro Iwata New Frontiers in QCD, February 5, 2010 CONCLUSION COMPASS is a multi-purpose spectrometer Muon program for nucleon spin structure Hadron program mainly for hadron spectroscopy COMPASS has started studies on spectroscopy VERY high statistics ( partly > 200 times previous work) More refined PWA is underway Status: Exotic 1 -+ 1 (1600) has been observed in - - + channel The 3 neutral mode shows consistent signals centrally produced charged 4 analysis is ongoing - - analysis is ongoing Analysis with kaonic channels is ongoing Interesting structures observed in KK channels
Backup Slides Takahiro Iwata New Frontiers in QCD, February 5, 2010
Takahiro Iwata New Frontiers in QCD, February 5, 2010 WAVE SETS IN PWA OF 2004 DATA
Takahiro Iwata New Frontiers in QCD, February 5, : (1800) IN 2004 PWA Constant width BW for (1800) With low mass background
Takahiro Iwata New Frontiers in QCD, February 5, 2010 multi- CHANNELS Selection of - n- (n=2, n=4) events 1 outgoing negative track with E track < 180 GeV n=2 and n=4 good clusters in ECAL1 and ECAL2 Energy balance: 180 < E n <200 GeV assuming the track to be a pion Co-planarity : -0.3 < n – p < 0.3 rad.
Takahiro Iwata New Frontiers in QCD, February 5, 2010 THE RICH DETECTOR 5 m 6 m 3 m C 4 F 10 photon detectors threshold momenta ● p = 2 GeV/c ● p K = 9 GeV/c ● p P =17 GeV/c radiator gas: C 4 F 10 mirror wall: 20 m 2 surface photon-detectors: outer part (75%) MWPC(pad RO) with CsI cathode inner part(25%) 576 MAPMTs with indiv. telescope Installed in 2005, Used in data taking from 2006