1 / 15

Measurement of Invariant Mass Spectra of Vector Meson Decaying in Nuclear Matter

Measurement of Invariant Mass Spectra of Vector Meson Decaying in Nuclear Matter. Kyoto Univ. a , KEK b , RIKEN c , CNS Univ. of Tokyo d , ICEPP Univ. of Tokyo e ,Tohoku Univ. f Megumi NARUKI a , J. Chiba b , H. En’yo c , H. Funahashi a , H. Hamagaki d , M. Ieiri b , M. Ishino e ,

maik
Télécharger la présentation

Measurement of Invariant Mass Spectra of Vector Meson Decaying in Nuclear Matter

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Measurement of Invariant Mass Spectraof Vector MesonDecaying in Nuclear Matter Kyoto Univ.a , KEKb, RIKENc, CNS Univ. of Tokyod, ICEPP Univ. of Tokyoe,Tohoku Univ.f Megumi NARUKIa, J. Chibab, H. En’yoc, H. Funahashia, H. Hamagakid, M. Ieirib, M. Ishinoe, H. Kandaf, M. Kitaguchia, S. Miharae, T. Miyashitaa, T. Murakamia, R. Mutoa, M. Nomachib, K. Ozawad, F. Sakumaa, O. Sasakib, H.D. Satoa, M. Sekimotob, T. Tabaruc, K.H. Tanakab, S. Yadamaa, S. Yokkaichic, Y. Yoshimuraa (KEK-PS E325 Collaboration) • Introduction • E325 Setup • Prelimirary Result of 2002 data analysis • Summary

  2. @ @ m m 5 MeV u d @ m 150 MeV s Physics The Origin of Quark Mass... In QCD vacuum In HOT/DENSE Matter Chiral Symmetry restoration How to detect the quark mass modificatoin? Vector Mesons

  3. Vector Meson Mass of Vector Mesons, ρ, ω and φ MV ≃ 2 x Mq + small Interaction term ρ/ω Mass Modification will be relatively large ～ 150MeV φ MassModification20～40MeV Narrow Width ～ 4.4MeV →Sensitive to the Mass Shape Modification Small Q value ( QKK=32MeV ) →Branching ratio Γφ→K +K-/ Γφ→e +e- will be another good probe

  4. KEK-PS E325 -Expected Signals- We measure Vector Meson Decay Inside a Nucleus, in 12GeV p+A → ρ,ω,φ + X. Expected Signals of φ→e+e- Invariant Mass Spectrum (Simulation using Hatsuda’s prediction)

  5. History

  6. ω ρ φ Invariant Mass Spectrum of (’98 data) P.R..L.. vol.86 (2001) p5019 fit result background Light Target (CH2/C） Heavy Target (Cu)

  7. Set up Hodoscope Aerogel Cherenkov Forward TOF Forward LG Calorimeter Rear LG Calorimeter Side LG Calorimeter Barrel Drift Chamber Cylindrical DC 12GeV proton beam Rear Gas Cherenkov Vertex DC Front Gas Cherenkov

  8. New Detectors 950mm Forward EM Calorimeter -electron ID efficiency 425mm • Vertex Drift Chamber • momentum resolution • vertex resolution

  9. Target 90mm 23mm C Cu

  10. Invariant Mass Spectrum of e+e- (’02 Data) Counts/20MeV/c2 Counts/20MeV/c2 Fit Result ω ρ φ Back Ground Light Target (Carbon) GeV/c2 Heavy Target (Copper) GeV/c2

  11. BackGround SubtractedInvariant Mass Spectrum of e+e- (’02 Data) Counts/20MeV/c2 Counts/20MeV/c2 Fit Result ω ρ φ Light Target (Carbon) GeV/c2 Heavy Target (Copper) GeV/c2

  12. Summary • KEK PS-E325 detects 12GeV p+A→ρ,ω,φ+X reactions in both K+K- and e+e- channel. We measure the shape of the invariant mass and the branching ratio. • In the 2002 e+e- data, we have observed excesses over the known hadronic sources below the ω peak. Obtained ρ/ω ratio support that this excess is mainly due to the modifications of ρ meson. • Some hint on φ meson modifications is seen. • In near future, statistics will be about 2 times larger. We plan to obtain the dependence of the momentum of vector mesons.

  13. Electron ID

  14. Electron ID Performance

  15. K0→π+π- Λ→pπ- Mass Resolution MK= 494.8MeV/c2 (PDG497.7MeV/c2) dMk = 6.1MeV/c2 (Sim 6.3MeV ) ML= 1115.4-5MeV/c2 (PDG1115.7MeV/c2) dML = 1.8-2.4MeV/c2 (Sim 1.9MeV) φ→KK 2．4MeVφ→ee 12MeV

More Related