HadronHadron spectroscopyspectroscopy inin diffractivediffractive andand centralcentral productionproduction processesprocesses atat COMPASSCOMPASS
Prometeusz Jasinski for the COMPASS collaboration
- Diffraction 2010 - Beyond the qq model
Constituent quark model QCD prediction: meson states beyond
Color neutral qq systems Hybrids: qqg Quantum numbers (IG) JPC Tetraquarks: (qq)(qq) P=(-1)L+1 C=(-1)L+S G=(-1)I+L+1 → “Spin exotics” JPC multiplets: 0, 0, 1, 1, 1, 2, … Forbidden: 0 , 0 , 1 , 2 , 3 , ... Glueballs: gg, ggg
Production mechanisms
Diffractive Scattering Central Production The COMPASS Spectrometer 2008/2009
The COMPASS Spectrometer 2008/2009
Beam properties Beam properties Beam energy 190 GeV/c² Beam energy 190 GeV/c² Beam composition: Beam composition: : : p = 0.97 : 0.024 : 0.008 : : p = 0.97 : 0.024 : 0.008 or or : : p = 0.24 : 0.014 : 0.75 : : p = 0.24 : 0.014 : 0.75 Up to 5 x 10⁶ particles/s Up to 5 x 10⁶ particles/s
beam
The COMPASS Spectrometer 2008/2009
CEDARCEDAR detectors detectors for for beambeam particle particle identification identification
The COMPASS Spectrometer 2008/2009
CEDARCEDAR detectors detectors for for beambeam particle particle identification identification
Cerenkov Differential counter with Achromatic Ring Focus
The COMPASS Spectrometer 2008/2009
RecoilRecoil proton proton detecto detectorr aroundaround 4040 cm cm long long lH2 lH2 target target oror ArrayArray of of solid solid state state discs discs
The COMPASS Spectrometer 2008/2009
The COMPASS Spectrometer 2008/2009 Further important upgrades ECALECAL Laser Laser monitoringmonitoring system, system, radhard glass, Sandwich veto radhard glass, Sandwich veto shashlikshashlik modules modules matchingmatching the the spectrometer spectrometer acceptanceacceptance
RICHRICH upgrade in 2006 SeveralSeveral tracking tracking upgrade in 2006 detectorsdetectors upgraded: upgraded: coldcold Silicon Silicon stations, stations, PixelPixel GEMs, GEMs, Micromegas,Micromegas, ...... And much more not mentioned here. Some results of p → p recoil
- - - - ● Visible well established Isobar a (1260), a (1320) andIsobar (1670) X 1 2 X 2 +/0 0 ● COMPASS observed in 2004 data the exotic (JPC=1) (1600) (see next talk) -/0 0 ● The hadron run will exceed world's statistics p p target by a factortarget of 100 p p recoil recoil
First PWA results of p → p recoil
Reduction factor of ~1/2 as expected by isospin symmetry
Isobar model, 42 waves including background, mass independent fit, comparison of neutral and charged modes with normalization to a 2 Selected results of p → p recoil
- - - - Analysis of diffractivelyIsobar produced X X systems 0 PWA currently being performed More results expected soon 0 p p target target p p recoil recoil
Selected results of p → p recoil
- - ● Isobar Tagging incoming beam Kaons X ● Many states in the system need confirmation ● Outnumbering previous results p by a factor of ~3 target p recoil
Selected results of p → p fast recoil
- - + ● Analysis of 4 pion central production demonstrates the spectrometer's - excellent acceptance and resolution X ● Looking at the region around f (1500) + 0 to study the previously quoted p target - existence of more than one resonance p recoil
Selected results of p → K Kp recoil
●final state analysis - - - - ● PID of charged Kaons by RICH Isobar ● K identified byX decay vertex +/0 s 0 ● separation of centrally and diffractively X produced systems by rapidity gap -/0 0 p ● Analysisp of disputed branching ratios of target resonancestarget such as f (1370) p p 0 recoil recoil
Some results on p → p recoil Selected results for p p → p p recoil p p p p ● Tagging the proton in the h+ beam → Isobar Isobar X ● Hadro-producedX baryon spectroscopy / ● Accessing regions of high masses and+ angular momenta ● Rich baryon spectrum to be - p p target distinguishedtarget p p recoil recoil
Summary and outlook
● After the spectrometer upgrade COMPASS took data with different hadron beams in 2008 and 2009
● both, charged and neutral, final state particles accessible →
● COMPASS has access many interesting channels in Meson and Baryon spectroscopy
● COMPASS statistics exceeds the one by previous experiments by a factor of up to 100
● Analyses using PWA techniques are ongoing
● We are expecting much more interesting results very soon
● interesting results expected very soon, also with nuclear targets
● Collaborators are very welcome!
Thank you
Backup slides
Details of PWA for 3 pi final state
Gottfried-Jackson Frame
Additional plots for Ks Ks
The diffractive process is still clearly visible in the invariant mass of Kpi as resonances.
Additional distributions for pKK