fromto

Kaon Decay Experiments at J-PARC
Takeshi K. Komatsubara (KEK-IPNS)
7-8 June 2004 KEK-PS External Review 2004 @KEK

Takeshi K. Komatsubara (KEK-IPNS)

1

Kaon Decay Experiments at J-PARC

Outline [in the next 24 slides, 25 minutes]• past/current program at KEK-PS– history∗ E246/E470: T-violating PT in K+ !  0 +  , .. [J.Imazato]∗ E391a: CP-violating decay K0L !  0  ¯ [T.Inagaki]• future program at J-PARC new 50GeV-PS– Physics Motivation– Letters of Intent for J-PARC kaon experiments∗ beamlines, detectors• future kaon programs in foreign countries• Roads to the J-PARC experiments

Takeshi K. Komatsubara (KEK-IPNS)

2Kaon Decay Experiments at J-PARC

KEK-PSBNL-AGS

1960

FNAL/CERN

Experiments started (32GeV).

1964(the year I was born)

1977

Experiments started (12GeV).

K0L → π + π −E10: K+ → π + ν ν̄E89,104: K+ → µ+ νH
E99,195: PL in K+ → µ+ ν
E137: K0L → µe

←→

1993

K0L → µe

direct CPV: ²0 /²K+ → π + µ+ e−

0 rare decays
KLK+ → π + ν ν̄KS0 decays

Booster
E162: K0L → π + π − e+ e−
E246,470: PT in K+ → π 0 µ+ ν, ..
E391a: K0L → π 0 ν ν̄* 1992∼ US-Japan kaon program (BNL-E787/E949, FNAL-KTeV)

Takeshi K. Komatsubara (KEK-IPNS)

3

Kaon Decay Experiments at J-PARC

KEK-PS experiments by International Collaborations

E246/E470

E391a

Japan +Russia, Canada, USA, Korea

Japan +Russia, USA, Taiwan, Korea

Takeshi K. Komatsubara (KEK-IPNS)

4Kaon Decay Experiments at J-PARC

Japan-US HEP program: kaon experiments

Range (cm)BNL-E949/E787
42FNAL-KTeV,Re(ε /ε)E787/E949

40383634E731 93
NA31 93
NA48 01 (prel)

7.4 ± 5.9
23.0 ± 6.5
15.3 ± 2.6

KTEV 01 (prel)

20.7 ± 2.8320102030(x10-4)

30

New World Ave.

17.2 ± 1.8

2890

100

110

120130140150

Energy (MeV)

USA, Canada, Russia +KEK, RCNP, Osaka, Kyoto,Fukui, NDA
Takeshi K. Komatsubara (KEK-IPNS)

USA, Brazil +Osaka
5Kaon Decay Experiments at J-PARC

What are we aiming at in the next @ J-PARC ?
Standard Model of Particle Physics (Cabibbo-Kobayashi-Maskawa matrix)           !#"$ %'&)(*,+.-0/ 

1 3!#"2$ 4
 $  $ %5& 6(7+.-0/ 8( ) * +,).--/     "!$#%  '&




- CP is violated (η 6= 0)- FCNC decays are really rare.
Then,



• Where is (ρ, η) located ?

Takeshi K. Komatsubara (KEK-IPNS)• Does ηKM explain everything ??

6Kaon Decay Experiments at J-PARC

“Golden” Modes: small theoretical uncertainties
K meson:
K+ → π + ν ν̄, K0L → π 0 ν ν̄

B meson:B 0 (B 0 ) → V KS , ∆Ms /∆Md































|∆B|=2 mixing processes|∆S|=1 rare-decay processes

different contributions from “New Physics” (Quark Flavor Physics)

Takeshi K. Komatsubara (KEK-IPNS)

7

Kaon Decay Experiments at J-PARCB.R.(K → πν ν̄) in the SM
K + : 4.84 × 10−11 • A4 · X(xt )2 · [ (ρ0 − ρ)2 + η 2 ]KL0 : 2.12 × 10−10 • A4 · X(xt )2 · η 2

Takeshi K. Komatsubara (KEK-IPNS)

8Kaon Decay Experiments at J-PARC

(ρ, η) constraints @LP03
1.5
excluded area has < 0.05 CL

1∆md∆ms & ∆md

0.5

αηεK

γ0β

sin 2β(WA)|Vub/Vcb|
-0.5

εK-1

CKM

fitterLP 2003

-1.5-1-0.5

00.5

11.52ρ

SM prediction

Buras et al
hep-ph/0405132

accuracy

theoretical uncertainties

K + → π + ν ν̄

(7.8 ± 1.2) × 10−11±15%±7%0→ π 0 ν ν̄KL(3.0 ± 0.6) × 10−11±20%

1-2%

Takeshi K. Komatsubara (KEK-IPNS)

9Kaon Decay Experiments at J-PARC

∆S = 1 (ρ, η)
3

ΚL−.η

Isidori & Unterdorfer, hep-ph/0311084

π0e+e−
[ΚS π0e+e−]
ΚL

2µ+µ−


[ΚL

γγ, ΚL

γl+l−

ΚL→ e+e−µ+µ−]

1ACP(ψKS)

νπ+ ν+Κ∆MBdVub

0-2Vcb-1

Takeshi K. Komatsubara (KEK-IPNS)

011023−ρ4Kaon Decay Experiments at J-PARCB.R.(K+ → π + ν ν̄) beyond the SM• Minimal Flavor Violation

Buras, hep-ph/0310208
SMMFVK + → π + ν ν̄

(7.8 ± 1.2) × 10−11

19.1 × 10−110KL→ π 0 ν ν̄

(3.0 ± 0.6) × 10−11

9.9 × 10−11• B → ππ, Kπ and New Physics
Buras et al., PRL 92, 101804(2004), hep-ph/0402112
SMNP

K + → π + ν ν̄

(7.8 ± 1.2) × 10−11(7.5 ± 2.1) × 10−110→ π 0 ν ν̄KL(3.0 ± 0.6) × 10−11(3.1 ± 1.0) × 10−10* (sin2Φ1 )B 0 →ΦKS ≈ +0.9 ⇐ −0.96 ± 0.50 by BelleTakeshi K. Komatsubara (KEK-IPNS)

11Kaon Decay Experiments at J-PARC

5 LoI’s (out of 30) for J-PARC kaon experiments• KL neutral beamline– L-05: K0L → π 0 ν ν̄[T.Inagaki(KEK)]⇐= KEK-E391a• K + beamline of low-momentum (0.6 − 0.8 GeV/c): K + decay at rest
– L-04: K+ → π + ν ν̄[T.Komatsubara(KEK)]⇐= BNL-E949/E787– L-19: T-violation in K + decays [J.Imazato(KEK)/Yu.Kudenko(INR)]⇐= KEK-E246– L-16: medium-rare K + decays [C.Rangacharyulu(Saskatchewan)]⇐= KEK-E470– L-20: Ke3 branching ratio[S.Shimizu(Osaka)]⇐= KEK-E470/E246* L-05, L-04, and L-19 were regarded as “highlight” experiments of J-PARC Phase-1
in the assessment of NPFC.
Takeshi K. Komatsubara (KEK-IPNS)

12Kaon Decay Experiments at J-PARC

• T-violating PT
in K+ → π 0 µ+ ν, K+ → µ+ νγPT
• K+ → π 0 e+ ν =⇒ |Vus |K+PDG
E865 [10]KLPDGKTEV
Leutwyler and Roos [9]Bijnens and Talavera [11]Becirevic et al. [12]Jamin et al. [13]more sensitive searchfor New CPV physics

0.21

f+(0)(1-|Vud|2-|Vub|2)1/2

0.215

IVusI f+(0)

0.22

0.225

from KTeV, arXiv:hep-ex/0406001

Takeshi K. Komatsubara (KEK-IPNS)

13

Kaon Decay Experiments at J-PARC

Hadron Hall Layout Plan
Instructions of Project Director: Prof. Nagamiya
to the NP Construction Group (Sep 2003)• ...
• Design the experimental hall so as toaccommodate the three kaon decay experiments (L-05, L-04 and L-19)
in the future.
• Don’t shout the doors on the experiments which received a lower
evaluation. It may be that they would develop to become goodexperimental proposals in course of time.
• ...
Report on the Beamline Layout plan of the Hadron Exp Hall (Feb 2004)
http://www-ps.kek.jp/jhf-np/Layout/Layout.html
Takeshi K. Komatsubara (KEK-IPNS)

14

Kaon Decay Experiments at J-PARC

Hadron Hall Layout Plan

Takeshi K. Komatsubara (KEK-IPNS)

15

Kaon Decay Experiments at J-PARC

KL line at 16deg

Takeshi K. Komatsubara (KEK-IPNS)

and

16

K1.1 line(S-type)

Kaon Decay Experiments at J-PARC

K0.8/K1.1 line(C-type)

Takeshi K. Komatsubara (KEK-IPNS)

and

17

high-memontum line

Kaon Decay Experiments at J-PARC

L-05: K0L → π 0 ν ν̄

L-04: K+ → π + ν ν̄

• solenoidal spectrometeras BNL E949/E787• KEK-PS E391a→ Phase-1 → Phase-2• high-magfield (>2.0-Tesla),compact and segmented detector• > 100 signal events• > 50 signal events

Takeshi K. Komatsubara (KEK-IPNS)

18

Kaon Decay Experiments at J-PARC

L-19/-16: K+ → π 0 µ+ ν,
K+ → µ+ νγ, ..

L-20: K+ → π 0 e+ ν

MWPC2e+γ
MWPC1K+Degrader
SVD1SVD2γCsI(Tl)(cm)• π 0 detector, µ+ polarimeter• |Vus |: precision of 10−3• sensitivity to PT : ∼ 10−4

• high-magfield (>2.0-Tesla),compact and segmented detector• semileptonic, hadronic
and radiative modes

Takeshi K. Komatsubara (KEK-IPNS)• slowed-down K + decay in flight

19Kaon Decay Experiments at J-PARC

J-PARC 50GeV-PS operation (Slow Ext)    "!$#&%'+++)  %$* + + + +-/.0.123

KEK-PSAGS+++++,- %"*())-546))))

-754

J-PARC

J-PARC

Phase-1

modproton energy

12243030

GeV

protons per pulse

2.5

65

200

100

1012 /spill

cycle

4.0

6.4

3.42

4.42

sec

average current

0.1

1.63

9.5

3.6

µA

beam spill

2.0

4.1

0.7

1.7

sec

duty factor

0.50

0.64

0.20

0.39

instantaneous rate

1.31628659

Takeshi K. Komatsubara (KEK-IPNS)

201012 /sec

Kaon Decay Experiments at J-PARC

K0L → π 0 ν ν̄ in the US: KOPIO experiment @ BNL• RSVP (K0L → π 0 ν ν̄ + µ-e conversion) as
NSF Major Research Equipment program• construction from FY05,first physics run in FY10(expected)• Kyoto team from Japan

Takeshi K. Komatsubara (KEK-IPNS)

21

Kaon Decay Experiments at J-PARC

K+ → π + ν ν̄ in the US: CKM(E921) experiment @ FNAL
• RF-separated K + beam at 22 GeV/c• K+ → π + ν ν̄ decay in-flight for the first timeCKtMuc

CKM ApparatusdKaon
EntranceAngle
Tracker
BeamTimeStamp

VacuumVeto

Forward
Veto

Pion RICH
1 atm Neons bConversion
Veto
Plane
BM109
MagnetHoleVeto

Kaon
RICH.7 atm
CF4Upstream
Magnetic
Spectrometer
50 MHzSeparated
K+ Beam
22 GeV/c

Exit
Time
Plane

Beam
Interaction
VetoBeam
Dump
Downstream
Magnetic
Spectrometer

Muon
Veto

... was stopped by P5 (Oct 2003) due to budgetary limits of US-HEP.
Takeshi K. Komatsubara (KEK-IPNS)

22

Kaon Decay Experiments at J-PARC

• FNAL-CKM(E931) is being redesinged to P940:– un-separated K + beam at ∼45 GeV/c in KTeV hall
– K+ → π + ν ν̄ decay in-flight• CERN-NA48 working group’s EoI for NA48/3:– un-separated K + beam at ∼75 GeV/c– K+ → π + ν ν̄ decay in-flight• medium-rare K decays– DAΦNE-KLOE– Russia IHEP-OKA: RF-separated K ± beam @ U-70
Takeshi K. Komatsubara (KEK-IPNS)

23

Kaon Decay Experiments at J-PARC

Strategy (my personal view)
Perform the best particle-physics experiment in Hadron Hall.
1. KL neutral beamline:• investigate the possibility of first evidence for K0L → π 0 ν ν̄at A-line T1-target with the E391a apparatus [expressway]• long-term:
investigate the best way
for precise measurement of the branching ratio with> 100 signal events
2. low-momentum K + beamline• establish the design of K0.8 beamline• concerning K+ → π + ν ν̄:– watch the future of BNL-E949, FNAL-P940 and CERN-NA48/3– fully optimize the design of the new detector for K + decay at rest

Takeshi K. Komatsubara (KEK-IPNS)

24

Kaon Decay Experiments at J-PARC

Takeshi K. Komatsubara (KEK-IPNS)

25

Kaon Decay Experiments at J-PARC

Summary : fromto• We have had a long and strong history ofkaon-decay experiments at KEK-PS in Japan• The tradition continues at J-PARC 50GeV-PS
with its strong program.
• We would proceed to prepare a full-Proposal of“Kaon Physics at J-PARC”.
– NP04 is a point of departure for it.

Takeshi K. Komatsubara (KEK-IPNS)

26

Kaon Decay Experiments at J-PARC