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Investigation of the nuclear medium property using f meson as a probe

Investigation of the nuclear medium property using f meson as a probe. Hiroaki Ohnishi Advanced meson science Laboratory RIKEN. KEK-PS J-PARC. SPS, RHIC, LHC. QGP. neutron star. T. Hatsuda, H. Shiomi and H. Kuwabara Prog. Theor. Phys. 95(1996)1009. W.Weise NPA553, 59 (1993).

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Investigation of the nuclear medium property using f meson as a probe

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  1. Investigation of the nuclear medium property using f meson as a probe Hiroaki Ohnishi Advanced meson science Laboratory RIKEN

  2. KEK-PS J-PARC SPS, RHIC, LHC QGP neutron star T. Hatsuda, H. Shiomi and H. Kuwabara Prog. Theor. Phys. 95(1996)1009 W.Weise NPA553, 59 (1993). Introduction • Origin of hadron mass→Spontaneous breaking of chiral symmetry！　 • Under the extreme condition such as high temperature and/or density, restoration of its broken chiral symmetry has been expected Prediction from theory tells us, Mass of vector meson in medium will be decreasing when density increasing

  3. SPS, RHIC, LHC KEK-PS QGP neutron star W.Weise NPA553, 59 (1993). Introduction Vector meson production in p-A or γ-A → vector mesons are creating dynamically High energy heavy ion collisons →creating high temperature/density medium and vector meson dynamically • Experiments have been done to study property of the vector meson in medium, so far Mass shift of Φ/ω mesons innormal nuclear mater Width boarding of ρmeson? CERES KEK-PS E325 PRL98(2007)042501 NA60 CBELSA-TAPS PRL94(2005)192303

  4. f-Nucleus interaction？ • What we learn from KEK-PS E325 results　（PRL98(2007)042501） Reduction of the f meson mass observed ! (about 3%), when we selected slowly moving f mesons ここで、山縣さんに理論計算を紹介してもらいます f meson in nucleus can be modeled as More advanced measurement will be performedat J-PARC as E16 experiment. f meson is in the energy pocket created by nuclear potential i.e. Mass reduced due to binding energy of the system Formation of the f-mesic nucleus?? Is it possible to create f mesic nucleus withsuch a small potential depth? 3% mass reduction on f meson, expected depth of the potential must be about 30 MeV

  5. f meson bound state exist？ • There are many hints inΛhypernucleus production • Potential depth of Λ-Nucleus ～３０ＭｅＶ • Mass ofΛ＝１１１６ ＭｅＶ/c2 Those conditions are very similar with the case for f meson • In the case of Λ hypernucleus production via (p,K) reaction,momentum transfer for the reaction is about 400 MeV/c.This is far away from recoilless condition. Analogy from L hyper nucleus production, f meson bound state will be produced even if we selecting elementary process which has large momentum transfer

  6. f production via p(p-,n)f reaction Missing mass spectroscopy can bedone with forward going neutron. f production via p(p,f)f reaction Missing mass spectroscopy can bedone with forward going f meson. How to produce f with low momentum efficiently? • Cross section ~ 4 ub • Cross section ~ 20 ub • Momentum transfer ~ 400 MeV/c • Momentum transfer ~ 200 MeV/c

  7. f production via p(p-,n)f reaction Background = Huge!!!Quesi-free hyperon production etc. f production via p(p,f)f reaction Background = Huge!But, once one can identify third strangeness in the event, thenevent sample will be almost background free How to produce f with low momentum efficiently? f meson production with anti-proton will be primary candidate of the elementary process for the f mesoic-nucleus production.

  8. s s Φ K+ s u u s u u p Λ d d How to identify f meson bound state • Let’s focusing on decay mode • Mass of the f meson will be decreasing about 30 MeV. • i.e. 1019 MeV – 30 MeV = 989 MeV ~ 2 x MKaonMain decay mode for Φmeson, Φ→K+K-, will be suppress. • However, Φ meson is in nucleus. There are many nucleon surrounding them. 1019 MeV – 30 MeV + 938 MeV(proton)　　　　　　　　　　　　　　　　　＝ 1927 MeV > MKaon+MΛi.e.Φp→K+Λ will be a dominant decay mode,if f meson is in nucleus. (This mode is not suppressed by OZI role ) i.e. K+L in final state will be a good signal to ensure f meson in medium

  9. Concept for the experiment Nuclear target Outgoingf meson f meson bound state Reaction Anti-proton Missing mass Spectroscopy Decay L K+ Strangeness tag!!

  10. Experimental setup • Good tracking chamber and PID detector around target • Cylindrical Drift Chamber ＋ Kaon ID detector • f meson emitted to forward direction must be detect efficiently.

  11. Experimental setup(2) • Conventional • LEPS like setup • But large dipole magnetbehind solenoid magnetto maintain large forward angle acceptance • Challenging setup • Everything inside large solenoid magnet(~3m long, 1m diameter )

  12. Event rate estimation (2) • Comparison parameters in hypernuclear formation at KEK-SKS and new experiment for f meson bound state ～　240 Events are expected for one month of data taking period

  13. Summary • Based on the results reported by KEK-PS E325 (mass shift of f meson) together with a similarity between L hyper nucleus production via (p,K) reaction strongly suggested that the production of f mesic nucleus can be possible. • The most promising elementary process for the f mesic nucleus production will be pp→ff channel.(Background free experiment can be achieved, in principle) • Naïve event rate estimation tells us that 240 events candidate for f mesic nucleus will be produce per month,with beam intensity, 2x106/spill, for 1.3 GeV/c anti-proton.

  14. おまけ。。。。。。。

  15. Invariant mass spectra of f in nuclear medium via lepton pairs • Final state interaction の影響が少ないレプトン対測定は、核物質の性質をさぐる有力なツールとなる。 • ＫＥＫ－ＰＳ　Ｅ３２５実験の成功。（f->ee） • J-PARC でさらに詳細の研究が行なわれる 　 J-PARC E1６ 実験 • ミュオン対測定　：　可能である？がそもそも、出てくるミュオン運動量が低い。。。 • ee 測定とは相補的。それだけ？　

  16. そもそも、なぜ　f->mm measurement???? • ＣＥＲＮ－ＮＡ４５実験（高エネルギー重イオン衝突における電子‐陽電子対測定実験）が終わりレプトン対測定つながりでＮＡ６０に参戦してきたＨ．Ｓｐｅｃｈｔ教授（当時ハイデルベルグ大）がＮＡ６０最初の実験データ収集時に言っていた一言。。。　 • 私がＣＥＲＮ－ＮＡ６０で 実験をしていたとき、（高エネルギー重イオン衝突におけるミュオン対測定実験）　 • ＣＥＲＥＳで１年かかってとったデータ量を４分でとっている。。。 • 違いは、ＣＥＲＥＳには電子‐陽電子対トリガーが無い。ＮＡ６０にはミューオン対トリガーがある。 • ミューオン対測定なので標的が厚い！！！（インジウム標的、1g/cm2を５枚～5g/cm2を使用。）　 • ただし、ＣＥＲＮではビーム運動量は　核子あたり158 GeV/c、相手にしてるミュオン運動量は数十ＧｅＶ！だから勝負になった。 • Ｊ－ＰＡＲＣで、測定したい　low momentum fから崩壊するミュオン対測定って可能？　まず狙ってる運動量は？

  17. f->mm measurement　の可能性 • 素過程として　p(p-,n)f　を選択 • Beam momentum = 2 GeV/c とすると　生成断面積は　20 mb • 生成されるf meson の運動量分布　0.4< bg < 1.6 KEK-E325 のbg分布 • いま、検出器として標的を囲むようなＣＤＣ型のものを考える。カバーする範囲をビーム軸に対し　　0.5<q< p-0.5　とする。 • ミュオン対がアクセプタンスに入る場合の fの運動量分布 　 しかし、ミュオンの運動量分布は こんな低運動量ミュオントリガーは可能？

  18. How to measure low momentum f ( sqrt(s) < 2GeV ) • One of the example • SND detector • ee collider 実験 f->mm branching ratio を測定した（する）実験 この検出器ではミュオン４００ＭｅＶ以上　５３０ＭｅＶ以下を９０％以上の効率でＩＤ

  19. How to measure low momentum f -(2) • 500 MeV/c まではmuon ID 出来そう。では、500 MeV/c 以上　1200 MeV/c 以下のミュオンは？ ~3GeV/c までなら捕まえる検出器が作れる！ Belle KLM detector

  20. Muon detector Muon detector EMCal EMCal CDC CDC z z f meson physics at J-PARC • K中間子原子核探索実験　　　　 Ｊ－ＰＡＲＣ　Ｅ１５ (on going!)anti-Ｋ N の相互作用の明確な答えを出す • 原子核中で生成された　f->ee 測定 Ｊ－ＰＡＲＣ　Ｅ１６（on going!） • f中間子原子核生成　探索実験　　　　　Ｊ－ＰＡＲＣ　ＬｏＩ • 原子核中で生成された　f->mm測定　　 アイディアのみ（出来たらいいな）　 • 必要なものは？　どうやって？　今後の課題？　　 • さて、　f中間子原子核探索実験と　f->mm測定同時に出来ない？ Muon absorber ~40cm ~3m なんか、中野さんの言ってた検出器みたい 1.2m 標的周りを Muon absorber

  21. まとめ • Ｊ－ＰＡＲＣをfを用いた物質質量の起源探索の最終試験場にする！ • その第一弾がすでにＥ１５，Ｅ１６として準備中 • 第二弾実施のためには、 • 大強度反陽子ビームライン！ • 標的周りを囲む検出器システム！ • 大立体核前方スペクトロメーター 　　の建設が必要。 • なにはともあれ、(小沢さん的に言うと) 　　　　　　　　　　　　　　　　　　　　　　　　　夢を共有していただけるＣｏｌｌａｂｏｒａｔｏｒ　が必要（切実。。。）　 現在　７名。。。。 実験の具体化はこれから

  22. f->mmを測ると何がすばらしいのか？ • 標的原子核中での　

  23. f production via p(p-,n)f reaction Background = Huge!!!Quesi-free hyperon production etc. f production via p(p,f)f reaction Cross section ~ 4 ub How to produce f with low momentum efficiently? • Momentum of f generated • Momentum of f generated

  24. Today’s topics • Is there any way to embedded f meson in nuclear matter? • Analogy of pionic, kaonic nucleus • Study of invariant mass spectra of low momentum f meson in nuclear medium • study of f→e+e- : has been proposed as J-PARC E16 • study of f→m+m- : idea of the measurement will be presented in this talk!

  25. Event rate estimation • Event rate for f meson bound state formation are estimated based on the hypernuclear formation rate obtained at KEK-SKS • Event rate seen in hypernuclear formation via (p+,K+) reaction at KEK-PS/K6 with SKS spectrometer • 1x109p induced on 1g/cm2 Carbon target,about 20 grand state 12LC produced • Basic numbers used for the estimation • Beam intensity Ip = 2.0 x 106 / spill • Beam momentum used for the experiment = 1.3 GeV/c • Momentum transfer = 200 MeV/c • p-p →ΦΦcross section = 4/4π(mb/sr)=0.32(mb/sr) • Target thickness 2g/cm2 • Acceptance for forward spectrometer (120 msr) • K+Λ trigger efficiency (ΩCDC x BR(Φp→K+Λ)xBR(Λ→pπ)) = 1.7 sr • Relative capture rate　（sticking probability） • Rcapture = exp(-q2/qF2) , q: momentum transfer, qF: fermi momentum

  26. Muon detector EMCal CDC z Experimental setup(2) • Conventional • LEPS like setup • But large dipole magnetbehind solenoid magnetto maintain large forward angle acceptance Aerogel+Hodoscope

  27. Experimental setup(2) • Conventional • LEPS like setup • But large dipole magnetbehind solenoid magnetto maintain large forward angle acceptance If we designed acceptance coverage for the forward spectrometer ~ 120 mSr

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