Experimental Investigation for Diquark Degrees of Freedom in a Charmed Baryon at J-PARC

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 ▶ J-PARC High-momentum beam line ▶ E50 spectrometer system ▶ Expected spectrum Summary

2 / 24 Physics motivation

Fundamental building blocks of QCD = quarks and gluons Hadron dynamics : constituent quark ▶ ground state ▶ nuclear force excited states, exotic resonance ▶ 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 ▶ 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 ▶ 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 ▶ ∗− → π− D D s (67.7%) 0 Production cross section ▶ D → K+π− (3.93%) Decay property Decay measurement ⇒ Diquark correlation ▶ 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 -2 10 Normalized to strangeness production σ [ µ b] -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 ▶ × 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− ▶ Unseparated beam 1.0E+07 1.0E+06 − High resolution Counts/sec 1.0E+05 K ▶ ∆p/p ∼0.1% (rms) 1.0E+04 pbar ▶ 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.)

13 / 24 Spectrometer (High-rate detectors)

LH2-target

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 ▶ Momentum: 0.2–20 GeV/c ▶ Anale: < 40◦ ⇒ D∗: 50–60% ▶ Decay particle∼80% Resolution ▶ ∆p/p = 0.2% @ 5 GeV/c ▶ ∗ 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, εtotal = 0.5) Λc (g.s.): 1 nb production cross section ▶ Production ratio for excited states Background: simulated by JAM code. ▶ 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 ▶ π− → 0 ∗− + ▶ − → − 0 + + p Ξc + D + K K + p Ω + Ks + K − − 0∗ + 4 ▶ K + p → Ω + K + K Y baryons: yield = Yc × 10 ▶ π− → 0 0 + p Y + Ks Drell-Yan channels ▶ π− + p → Y 0 + K∗0 ▶ π− + p → n + µ+ + µ− ▶ π− + p → Y − + K∗+ ▶ K− + p → Y 0 + µ+ + µ− ▶ π− + p → Θ+ + K∗− ∗ K beam rate ∼1/100 3 Ξ baryons: yield = Yc × 10 ▶ K− + p → Ξ0 + K∗0 ▶ − → − ∗+ 0 π+ K + p Ξ + K :(Ks + ) ▶ π− → − 0 + + p Ξ + Ks + K ▶ π− + p → Ξ− + K∗0 + K+

18 / 24 Strangeness

Yield: 104–105/day @ 1 µb ▶ 4 g/cm2, 6 × 107/spill (∼ 106/spill for K beam) ▶ 50% acceptance, 50% efﬁciency (DAQ, PID, analysis) Y: qq + Q system @ strangeness sector ▶ π−p → Y ∗ + K∗0 reaction ▶ Production ratio: qq excitation mode ▶ Decay branching ratio: Γ(NK)/Γ(πΣ) Ξ: a + QQ system ▶ K− + p → Ξ∗ + K/K∗ and π− + p → Ξ∗ + K/K∗ + K reactions ▶ Heavier diquark (q − s, s − s) system ? ▶ λ and ρ mode excitation interchange Ω: QQQ system ▶ K− + p → Ω∗ + K/K∗ + K reaction ▶ 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 ▶ Scintillating ﬁber tracker ▶ T0 timing counter ▶ Large RPC for TOF measurement (collaboration with LEPS2) High speed DAQ ▶ Front-end electronics for trigger-less readout ▶ 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 ▶ Essential way to understand hadron structure ▶ Diquark correlation: λ and ρ mode excitation Experiment at the J-PARC high-p beam line ▶ Inclusive measurements by missing mass spectroscopy with multi-purpose spectrometer system ▶ Unique information from the production measurement ▶ Data taking of many reaction channels by high-speed DAQ Systematic study of baryons at J-PARC ▶ Excitation energy, production, decay with strangeness sector: qq + Q, q + QQ, QQQ ▶ pilot studies for the K10 beam line ▶ Systematics to understand hadron structure

22 / 24 J-PARC E50 collaboration

RCNP Tohoku U ▶ S. Ajimura, H. Asano, T. Nakano, ▶ K. Miwa H. Noumi, K. Shirotori, Y. Sugaya, Academia Sinica T.N. Takahashi, T. Yamaga ▶ T. Sawada, C.W. Chang KEK Korea U ▶ K. Aoki, Y. Morino, K. Ozawa ▶ J.K. Ahn RIKEN Osaka U ▶ Y. Ma, F. Sakuma ▶ R. Honda Tohoku ELPH Yamagata U ▶ T. Ishikawa ▶ Y. Miyachi JAEA JLab ▶ K. Tanida, Y. Ichikawa ▶ J.T. Goetz Kyoto U ▶ 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

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