measurement of k l decay g.y.lim ipns,kek. why k l → ? flavor changing neutral current br(k...
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Measurement of KL decay
G.Y.LimIPNS,KEK
Why KL→? Flavor Changing Neutral Current
Br(KL o ) = 6 1 ・ Im(VtdVts)2X
2(xt)
= 1.94 ・ 10-102A4X2
Strong Interaction : Factorized by Ke3 Decay
Very Small Theoretical Uncertainty
Negligible Charm contribution
In JHF era
Unitarity Triangle vertices Beyond Standard Models
K+
KL
ACP(BJ/KS)MBd/MBs
G. Buchalla hep-ph/0110313 L.Littenberg HEPAP(2001)
E391a
Search for the decay KL
e+e-
Phys. Lett. B447(1999)
Phys. Rev. D61 (2000)
SM Prediction
L. Littenberg
E731E799
KTeV
BR
(KL
o )
Year
Decay Mode
Branching Ratio
Additional Particles
oo
+o
e
+ee
e+e
e+e ー
21.13 % 12.55 % 27.18 % 38.78 % 5.86 ・ 10-
4
<2.4 ・ 10-
7
1.68 ・ 10-
6
5.18 ・ 10-
5
3.62 ・ 10-
3
5.7 ・ 10-
4 4.61 ・ 10-
5
<5.6 ・ 10-
6
3.25 ・ 10-
7
10.0 ・ 10-
7
6.9 ・ 10-7
4 2Ch 2Ch 2Ch
1 2 2Ch 2Ch 2Ch 2Ch 3 2Ch 2Ch 2Ch
Decay Mode
Branching Ratio
Additional Particles
e+e
ee
ee
ee
eeee
ee
e
eee
<7.1 ・ 10-
7
2.06 ・ 10-
3
9.27 ・ 10-
4
7.15 ・ 10-
9
9 ・ 10-
12
3.5 ・ 10-
7
2.9 ・ 10-
9
4.1 ・ 10-
8
<5.1 ・ 10-
9
<4.3 ・ 10-
9
<5.9 ・ 10-
7
<4.7 ・ 10-
12
<6.1 ・ 10-
9
<6.2 ・ 10-
9
1 2Ch 2Ch 2 2Ch 2Ch 4Ch 4Ch 4Ch 2Ch 2Ch
2Ch 4Ch 2Ch
KL Decay Modes
Inefficiency of detection Inefficiency for charged particles
Detector Inefficiency
NIM A359 p478 (1995)
B.G. from KL-e+ Decay
Separating charged veto
High Energy Accelerator Research Organization, KEK
Faculty of Science and Engineering, Saga University
Department of Physics, Yamagata University
Department of Physics, Osaka University
Research Center for Nuclear Physics, Osaka University
National Defense Academy of Japan
Department of Physics, Ibaraki University
Joint Institute for Nuclear Research (Dubna) Russia
Department of Physics, University of Chicago
Fermi National Accelerator Laboratory
Department of Physics, Pusan National University
http://psux1.kek.jp/~e391/index.html
E391a Collaboration
KEK-PS E391a First dedicated experiment Pilot experiment for next step (JHF)
Figure out sources of background Developing method of rejection/estimation Realizing detector setup in high vacuum system
Compact detector system High acceptance Pencil beam Double decay chamber Highly evacuated decay region High PT selection
How far we have to go ?
Ke3, K3, K3
KTeV
E391a
JHF KOPIO(BNL)
S. M. Prediction
BR
(KL
o
)
Current Exp. Limit
New Physics (?)
Limit from K+ +PRL 84, 3768 (2000))
hep-ph/9908399hep-ph/9804412hep-ph/9808487
E391a Detector Setup
KL Nothing
pure CsI calorimeter 4 veto
system
Pencil Beam
Beam Profile
Layout of Beam survey
Moving Rail
Hodoscopes (15x15)
Profile detectors
Cerberus
Thermal Neutron Detectors (LiI, Li glass)
CsI
n/ detector (SLSD)
Lead glass
KL monitor
Liquid Scin.
BGO
Copper
KL monitoring using regeneration
H. Watanabe (2002)
: Revised B.G. estimation
Schedule Schedule
2001 2002 2003 2004
Data TakingAssembling Detector setup
Vacuum &
Cosmic TestAssembling
Front barrel Construction
Main barrelConstruction
Cosmic Run
Beam survey Engineering Run
Beam Test
Data Taking
Jan. Apr. Jul. Oct. Jan. Apr. Jul. Oct. Jan. Apr. Jul. Oct. Jan. Apr. Jul. Oct.
CsI
High flux of KL
Large acceptance Suppression of the Background
Standard model event B.G. linear to beam intensity Same S/N ratio (~3)
New physics Newly designed detectors system Physical motivation Following talk
Search Measurement
Large Number of KL Decay
Three orders larger KL flux Beam will be given from 2007 Two stages of construction
Limited beam lines Many experimental programs
KL Measurement Experiment at the first stage of
JHF Flexible approach
JHF
E391a at JHF
Experience at KEK-PS
Same veto system Low cost, earlier starting
New calorimeter resolution, clustering, efficiency
Fast DAQ High counting rates
Optimization of beam line KL/n/ ratio, production
T.Inagaki CP Violation in K Dec. (1998)
In future ・・・
E391aSM Expectation
KOPIO
JHF
Year
BR
(KL
o )
Summary
Golden channel to access CP violation (KL 0) KEK-PS E391a
Pilot experiment for JHF The first high sensitivity experiment Plan for data taking on 2003
JHF Real measurement of branching ratio Most clean measurement of CPV parameter Unitary triangle in K-system Potential to access the New Physics
LOI within 2002 !
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