Experimental investigation for diquark degrees of freedom in a charmed baryon at J-PARC T. N. Takahashi for the J-PARC E50 collaboration Research Center for Nuclear Physics (RCNP) Osaka University MENU2016 at Kyoto 1 / 24 Contents Physics motivation Diquark correlation Experiment I J-PARC High-momentum beam line I E50 spectrometer system I Expected spectrum Summary 2 / 24 Physics motivation Fundamental building blocks of QCD = quarks and gluons Hadron dynamics : constituent quark I ground state I nuclear force excited states, exotic resonance I not well described by constituent quark model diquark as effective degrees of freedom 3 / 24 Quark correlation q q ρ qq λ Q q color-spin interaction between quarks / 1/mi mj 3 light diquark pairs ) difficult to distinguish Heavy Q ) separate to Q and q − q We will investigate the diquark correlation by measurement of charmed baryon’s properties Level structure Production rate Decay branching ratio 4 / 24 Schematic level structure of heavy baryons λ/ρ modes Heavy quark spin doublet (~sHQ ~jrest) for jrest>0 I Heavy quark symmetry ) smaller mass splitting (or degeneracy) of doublet spin-spin isotope shift interaction q q ρmode ρ q-q Q q λmode q-q λ Q G.S. 5 / 24 Production ＊ π− D − D＊ q:momentum transfer p + Yc t-channel dominant λ mode excitation at forward angles one-step reaction 6 / 24 Production (2) L=0 L=1 L=2 − − + + Simulation 1/2 3/2 5/2 3/2 (?) (2625) (2595) (2880) c c c @ 1 nb Λ Λ Λ c Λ (2940) c Λ (2800) c (2520) Σ c (2455) Σ c Σ 1:2 3:2 The production rates are determined by the overlap of the wave function of initial and final states. momentum transfer ) orbital excitation Heavy quark doublet I spin/parity ) relative ratio 7 / 24 ∗ Yc Decay pattern Two decay patterns for two-body decay ∗ ! π Yc + Yc ∗ ! Yc D + N ρ mode λ mode Σc π D N qqQ qq Qq qqq ΓπΣc > ΓND ΓπΣc < ΓND − ++ p + D0 π + Σc π+ 0 + Σc 8 / 24 J-PARC E50 experiment Missing mass measurement K+ & π− :2–16 GeV/c 0 + Slow πs−: 0.5–1.7 GeV/c − ＊− D K π D − π Decay measurement − ± πs π &p: 0.2–4.0 GeV/c π+ p ＊+ p Λc OR 0 0 Σc D − ∗+ ∗− π + p ! Yc + D reaction Systematic measurement @ 20 GeV/c Excited states search Missing mass spectroscopy Excitation energy 0 I ∗− ! π− D D s (67.7%) 0 Production cross section I D ! K+π− (3.93%) Decay property Decay measurement ) Diquark correlation I π; ∗ p from Yc 9 / 24 Estimation of production cross section − *0 *- + π p -> ( K Λ &D Λc ) 2 10 [Regge] 0 High energy 2-body reaction based on 10 K*0Λ the Regge theory b] µ -2 [ 10 Normalized to strangeness production σ -4 *- + ) Charm production: ∼10−4 10 D Λc -6 10 1 2 4 8 s/sth No old data @ 10–20 GeV/c Assumed production cross section: σ ∼ 1 nb c.f. σ < 7 nb (BNL data) Small production cross section (expected) ) We need high-rate beam & multi-porpose spectrometer system. 10 / 24 J-PARC hadron hall High-p 11 / 24 High momentum beam line for secondary beam Sanford-Wang High intensity acceptance: 2 msr%, 132 m I × 7 π > 1.0 10 Hz (< 20 GeV/c) Prod. Angle = 0 deg. (Neg.) • 6×107 π−/spill on E50 1.0E+09 experimental target 1.0E+08 π− I Unseparated beam 1.0E+07 1.0E+06 − High resolution Counts/sec 1.0E+05 K I ∆p/p ∼0.1% (rms) 1.0E+04 pbar I Momentum dispersive optics 1.0E+03 0 5 10 15 20 method [GeV/c] Exp. Target (FF) Collimator 15kW Loss Target Dispersive Focal Point (DFP) (SM) 12 / 24 Spectrometer (Realistic design is ongoing.) 2m 13 / 24 Spectrometer (High-rate detectors) LH2-target T0 Fiber tracker Beam π- 2m 14 / 24 Spectrometer (Charmed baryon prod. and decay) PID counter K+ Fiber wall Internal TOF π- - Pole face πs detector π+ Ring Image LH2-target Cherenkov - Counter T0 π TOF wall DC - Fiber tracker Beam π Internal DC 2m 15 / 24 Spectrometer performance + 0 + Decay angle: Λc (2940) ! Σc (2455) +π Acceptance 100% acceptance I Momentum: 0.2–20 GeV/c I Anale: < 40◦ ) D∗: 50–60% I Decay particle∼80% Resolution I ∆p/p = 0:2% @ 5 GeV/c I ∗ 2 ∆MΛc = 10 MeV @ 2.8 GeV/c 16 / 24 Expected spectra Simulation (2625) (2595) (2880) c c c @ 1 nb Λ Λ Λ c Λ (2940) c Λ (2800) c (2520) Σ c (2455) Σ c Σ 13 ∼2,000 counts @ Npot = 8.64×10 (100 days, "total = 0:5) Λc (g.s.): 1 nb production cross section I Production ratio for excited states Background: simulated by JAM code. I D∗ tagging reduces B.G. by a factor of 2×106. Achievable sensitivity of 0.1 – 0.2 nb (3σ level, Γ < 100 MeV) 17 / 24 Many physics channels Main channel: Charmed baryons (Q + qq) − + ∗− π + p ! Yc + D Data rate: < 0.1 kHz Byproducts 2 Ξc baryons Ω baryons : yield = Yc × 10 I π− ! 0 ∗− + I − ! − 0 + + p Ξc + D + K K + p Ω + Ks + K − − 0∗ + 4 I K + p ! Ω + K + K Y baryons: yield = Yc × 10 I π− ! 0 0 + p Y + Ks Drell-Yan channels I π− + p ! Y 0 + K∗0 I π− + p ! n + µ+ + µ− I π− + p ! Y − + K∗+ I K− + p ! Y 0 + µ+ + µ− I π− + p ! Θ+ + K∗− ∗ K beam rate ∼1/100 3 Ξ baryons: yield = Yc × 10 I K− + p ! Ξ0 + K∗0 I − ! − ∗+ 0 π+ K + p Ξ + K :(Ks + ) I π− ! − 0 + + p Ξ + Ks + K I π− + p ! Ξ− + K∗0 + K+ 18 / 24 Strangeness Yield: 104–105/day @ 1 µb I 4 g/cm2, 6 × 107/spill (∼ 106/spill for K beam) I 50% acceptance, 50% efficiency (DAQ, PID, analysis) Y: qq + Q system @ strangeness sector I π−p ! Y ∗ + K∗0 reaction I Production ratio: qq excitation mode I Decay branching ratio: Γ(NK)/Γ(πΣ) Ξ: a + QQ system I K− + p ! Ξ∗ + K/K∗ and π− + p ! Ξ∗ + K/K∗ + K reactions I Heavier diquark (q − s, s − s) system ? I λ and ρ mode excitation interchange Ω: QQQ system I K− + p ! Ω∗ + K/K∗ + K reaction I Much simpler system: Diquark less system ? 19 / 24 Data acquisition system : free-streaming DAQ Detector Buffer, FrontEnd Electronics Load balancer local storage TOF PC Filter KEKCC PC PC RCNP ・・・ Fiber PC ・・・ spill-by-spill switch RICH PC PC DC PC 10G/40G Ethernet Monitor InfiniBand Xilinx MGT 1G/2.5G/5G/10G Ethernet PC Frontend modules Buffer PCs Filter PCs Storage Self or periodic Data accumulation Event (<0.5 GB/spill) ∼ ∼ trigger 50 GB/spill ( 250 reconstruction Local storage ∼ Gbps, 2 sec.) using CPUs and/or 30,000 ch Transferred to ! GPUs Derandomized KEKCC/RCNP ∼10GB/sec 20 / 24 Ongoing R&D works High speed and/or high performance detectors I Scintillating fiber tracker I T0 timing counter I Large RPC for TOF measurement (collaboration with LEPS2) High speed DAQ I Front-end electronics for trigger-less readout I Test bench for free-streaming DAQ • Load-balancing of CPU/GPU (collaboration with ALICE O2 project) • Fast on-line track reconstruction J-PARC High-p collaboration J-PARC E16 (talk by Y. Komatsu, 26-MNI-2-2) J-PARC E50 future Heavy Ion project at J-PARC 21 / 24 Summary Charmed baryon spectroscopy I Essential way to understand hadron structure I Diquark correlation: λ and ρ mode excitation Experiment at the J-PARC high-p beam line I Inclusive measurements by missing mass spectroscopy with multi-purpose spectrometer system I Unique information from the production measurement I Data taking of many reaction channels by high-speed DAQ Systematic study of baryons at J-PARC I Excitation energy, production, decay with strangeness sector: qq + Q, q + QQ, QQQ I pilot studies for the K10 beam line I Systematics to understand hadron structure 22 / 24 J-PARC E50 collaboration RCNP Tohoku U I S. Ajimura, H. Asano, T. Nakano, I K. Miwa H. Noumi, K. Shirotori, Y. Sugaya, Academia Sinica T.N. Takahashi, T. Yamaga I T. Sawada, C.W. Chang KEK Korea U I K. Aoki, Y. Morino, K. Ozawa I J.K. Ahn RIKEN Osaka U I Y. Ma, F. Sakuma I R. Honda Tohoku ELPH Yamagata U I T. Ishikawa I Y. Miyachi JAEA JLab I K. Tanida, Y. Ichikawa I J.T. Goetz Kyoto U I M. Naruki 23 / 24 Spectrometer (Drell-Yan) PID counter Muon detector μ+ Fiber wall Internal TOF μ- Pole face detector Ring Image LH2-target Cherenkov Counter T0 TOF wall DC - Fiber tracker Beam π Internal DC 2m 24 / 24.