K K π +- Preliminary Results on γ γ

Transcription

1 Vladimir Savinov, Univerity of Pittburgh Preliminary Reult on γ γ Two-Photon Production of Hadron K K π e + e + γ Global objective: provide data to undertand the phenomenon of confinement by tudying hadronic reonance below 1.7 GeV/c 2 that decay into K K π final tate. e - γ Repreenting CLEO Collaboration vp3@pitt.edu e - Motivation Experimental Tool Selection Criteria Sytematic Preliminary Reult Interpretation PANIC 02 1 October 3, 2002

2 Vladimir Savinov, Univerity of Pittburgh γ γ η(1440) Preliminary Reult on γ γ PANIC 02 2 October 3, 2002 K K π K K π Undertanding Hadron Ma Spectrum Quantatively would be Fundamental Verification of Low-Energy QCD Do we undertand thi pectrum theoretically? ak a theorit... Do we undertand thi pectrum experimentally? NO Check PDG review and try to make ene of all reported low-ma reonance! Thi tudy: hadron with mae below 1.7 GeV/c that decay to final tate K K π Experimental tool: production in two-photon colliion: Two-photon cro ection ~ Γ F (Q, Q ) γ γ Propertie of two-photon event: booted along beam axi, difficult to trigger on, tranvere momentum of the entire event peak at low value, no glueball produced 2

3 Vladimir Savinov, Univerity of Pittburgh Preliminary Reult on γ γ Experimental Statu of η(1440) Ma region between 1200 and 1500 MeV contain everal poorly-undertood hadron. Some of thee are, poibly, due to gluonic degree of freedom. η(1440) i one of thee hadron: wa oberved in hadron colliion and radiative decay of J/ϕ, not oberved in two-photon colliion until recently - glueball? Experiment diagree about the propertie of thi reonance... K K π PANIC 02 3 October 3, 2002

4 Vladimir Savinov, Univerity of Pittburgh L3 Collaboration / Phyic Letter B 501 (2001) 1 11 Recent new on η(1440) Preliminary Reult on γ γ K K π (BR ~ 1 for - meon) Γ γγ too mall for a meon - mixing with a glueball? An independent verification would be very ueful, alo, expecting larger ignal with CLEO PANIC 02 4 October 3, 2002

5 Vladimir Savinov, Univerity of Pittburgh Preliminary Reult on γ γ K K π Helium Reervoir Muon Chamber Superconducting Coil Barrel Shower Detector Drift Chamber SVX Detector Micro-Beta Quadrupole Vertex Detector End Cap Time of Flight Pole Tip Shower Detector Time of Flight Scintillator Magnet Yoke raf Meter PANIC 02 5 October 3, 2002

6 Vladimir Savinov, Univerity of Pittburgh Event Selection Criteria Preliminary Reult on γ γ K K π - Exactly four recontructed charged track in the entire detector (13% efficiency, 20% yt.) - Exactly 1 K candidate (vertex radially diplaced by two or more tandard deviation - Signal candidate propertie: - tranvere momentum below 100 MeV/c Thi election i baed (in part) on the hermeticity of CLEO detector, efficiency i hown for 1475 MeV - amount of energy detected in calorimeter in unmatched cluter below 100 MeV - at leat one large tranvere momentum track reaching barrel calorimeter - make ure event were recorded with reliable trigger and pa beam-ga rejection - 3 tandard deviation PID coniteny for charged K and non-k π uing TOF and dedx Efficiency of thi election for MC ample (independent data i alo ued): Signal MC (η(1440)): 0.84% (total ytematic i 30%) Thi i not unuual for low-ma untagged two-photon event PANIC 02 6 October 3, 2002

7 Vladimir Savinov, Univerity of Pittburgh Preliminary Reult on γ γ K K π Uing Data to Meaure Efficiencie and Etimate Sytematic Excluive two-photon K pair in data Event / 5 MeV/c 2 inv. ma K (GeV/c ) 2 inv. ma K (GeV/c ) 2 Invariant ma of K K candidate 2 (GeV/c ) PANIC 02 7 October 3, 2002

8 Vladimir Savinov, Univerity of Pittburgh Preliminary Reult on γ γ K K π Two-Photon K Pair Below 1.4 GeV/c 2 are utilized Tranvere momentum in calibration data (point) and ignal MC (line) P (GeV/c) 2 (GeV/c ) Invariant ma of K candidate in calibration data at low invariant ma PANIC 02 8 October 3, 2002

9 Vladimir Savinov, Univerity of Pittburgh Preliminary Reult on γ γ Tight Selection Criteria and Two-Photon Background K K π Tranvere momentum v unmatched energy for bckg K * + K * - two-photon MC - thi effect i verified in data! DATA election affect the hape of ptran (GeV/c) P Signal MC P (GeV/c) ame hape before and after election E (GeV) Tranvere momentum for ignal candidate in data (below 2 GeV/c 2 ) and ignal η(1440) MC before and after unmatched energy election PANIC 02 9 October 3, 2002

10 Vladimir Savinov, Univerity of Pittburgh Preliminary Reult on γ γ Some Important Ditribution in Signal Data K K π kev/cm dedx 1/β TOF (W < 2.0 GeV/c 2) P(GeV/c) Thee ditribution are hown for data after applying all election criteria (for right plot we removed PID requirement). Plot prove that there are K K π event in data. PANIC October 3, 2002

11 Vladimir Savinov, Univerity of Pittburgh Preliminary Reult on γ γ Teting the Analyi on η Μeaurement c K K π Tight election Looened election We obtain central value of 6.7 kev in both tet, while we reported Γ γγ (η ) = 7.6 kev 0.8 kev (PRL 85, 3095 (2000)) - good (ame data ued). c PANIC October 3, 2002

12 Vladimir Savinov, Univerity of Pittburgh Preliminary Reult on γ γ K K π Invariant Ma Ditribution for Signal Candidate Can only do upper limit, no obervation. I thi urpriing? Not necearily: L3 integrated luminoity: 3% of CLEO but L3 γγ cro ection: 6 time larger We can do qrt(5) better with bckg 90% CL UL: approx. < 33 event Efficiency (with ytematic): Luminoity: 13.8 invere femtobarn Cro ection per 1 kev γγ width: 36 pb Setting 90% CL UL on the product: Γ (η(1440)) Β (η(1440) > ) γγ K K π < 14 ev (ytematic included, preliminary) (L3 report: ev for thi value) PANIC October 3, 2002

13 Vladimir Savinov, Univerity of Pittburgh Preliminary Reult on γ γ K K π Two More Fit for Other Ma and Width Hypothee PANIC October 3, 2002

14 Vladimir Savinov, Univerity of Pittburgh Concluion Preliminary Reult on γ γ K K π In our analyi we do not oberve any narrow reonance between 1.3 GeV and 1.7 GeV, alo, we do not confirm L3 obervation. For example, auming M = GeV, Γ = 50 MeV Γ (η(1440)) Β (η(1440) > ) γγ We et upper limit on the product of partial two-photon width and branching fraction (K branching fraction included) K K π < 14 ev (thi i 2.9 σ below L3 number of 49 ev 12 ev) Final reult of our analyi will include table of upper limit etimated uing variou value for the mytery reonance ma and width (analyi continue). PANIC October 3, 2002