1. Search for Non-Standard Model Physics
Using the Transverse Muon Polarization
in Stopped K+ Decay
The E06 TREK Experiment
Sébastien Bianchin
TRIUMF / University of British Columbia
on behalf of the TREK-E06 Collaboration
PANIC 2011 (July 24th – 29th, 2001)
Massachusetts Institute of Technology, MA, USA
Thursday, July 28th 2011
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

2. The TREK Program at J-PARC
Outline
 Hadron Facility at J-PARC
 TREK Program TREK = Time Reversal Experiment with Kaons
 Search for Time Reversal Symmetry Violation
 Test of Lepton Universality
 Search for Heavy Neutrinos Lower intensity
 TREK Apparatus -- R & D
 Status & Schedule
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

3. J-PARC Facility
Linac (KEK/JAEA ）
North
3 GeV
Synchrotron
Neutrino Beams
(to Kamioka)
Materials and Life
Experimental
50 G Facility
eV
Syn
chr
otro
n
CY2007 Beams Hadron Exp.
JFY2008 Beams Facility
S. Bianchin
JFY2009 BeamsPANIC 2011 (July 24 th
– 29th 2011)

4. J-PARC Hadron Hall
Beam
Dump
K1.8
KL
K1.8BR
K1.1
S-type
30~50 GeV Production
primary beam K1.1BR
target (T1)
C-type
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

5. K1.1BR = K0.8 Beam Line Installation
 K1.1BR completed in summer 2010 using the supplementary budget of FY09
 Commissioned in Oct. 2010 by the TREK collaboration
- ESS Length of 2.0m to be increased to 2.5m
- Length Q8-FF of 3.3m to be reduced to 1.5m (remove iron shielding wall)
Q1, Q2
D2
T1 D1
Q3, Q4
IFX,
Proton beam IFY SX1 ESS
Q5, Q6
SX2
K1.1-BR SX1 MS D3
HFOC
Q7 Q8
• FF
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

6. Stopped K+ Experiments @ K1.1BR
 E06 (TREK)
“Measurement of T-violating transverse muon
polarization (PT) in K+→ 0   decay”
Stage-1, 270 kW
 P36 (LFU)
“Measurement of RK = Γ(K+ →e+ν ) / Γ(K+ → + ν )
and search for heavy sterile neutrinos”
Stage-1 (PAC11-Jan’11); 30 kW
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

7. The TREK Collaboration
CANADA RUSSIA
University of British Columbia Russian Academy of Sciences (RAS)
University of Manitoba Institute for Nuclear Research (INR)--Moscow
Universite de Montreal
University of Saskatchewan JAPAN
TRIUMF Osaka University
National Defense Academy
USA Tohoku University
Massachusetts Inst. of Technology (MIT) High Energy Accelerator Research Org. (KEK)
University of South Carolina Kyoto University
Iowa State University Tokyo Institute of Technology (TiTech)
Hampton University
Jefferson Laboratory VIETNAM
University of Natural Sciences
New collaborators are welcome!
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

8. Transverse  + Polarization in the K 3 Decay
http://trek.kek.jp
K →  decay
+ 0 +
 PT is T-odd, and spurious effects from final state interaction
are small: PT (FSI) < 10-5
Non-zero PT is a signature of T violation.
 Standard Model (SM) contribution to P : P (SM) < 10-7
- T T
Hence PT in the range 10-3 – 10-5 is a sensitive probe of
CP violation beyond the SM.
 There are theoretical models of new physics which allow
a sizable PT value without conflicting with other
experimental constraints.
The TREK experiment aims for a sensitivity of 10-4
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

9. The TREK Experimental Apparatus
K+→0+ Use an upgraded E246 detector
Active Polarimeter
( Japan )
New Fibre Target
( Canada )
C0,C1 GEM
( USA )
CsI(Tl) readout ( Russia )
PT is measured as the azimuthal asymmetry Ae+ of the + decay positrons
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

10. The Stopped Beam Method K+→ 0  + 
Double ratio experiment
AT = (Afwd - Abwd ) / 2
Ncw - Nccw
Afwd(bwd) =
Ncw + Nccw
PT = AT / {α <cosθT>}
α : analyzing power
<cosθT> : attenuation factor
Imξ = PT / KF : physics parameter
KF : kinematic factor
Current limit from KEK--E246 bwd -  0 (γ ) fwd -  0 (γ )
PT = - 0.0017 ± 0.0023(stat) ± 0.0011(syst)
|PT | < 0.005 : 90% C.L.
Imξ = - 0.0053 ± 0.0071(stat) ± 0.0036(syst)
|Imξ | < 0.016 : 90% C.L
Statistical error dominates
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

11. Expected Sensitivity
We are aiming for a sensitivity of δPT ~ 10-4
 δPTstat ~ 0.05 δPTstat (E246) ~ 10-4 : 1.4 x 107 sec runtime
1) Beam intensity x 30
2) Detector acceptance x 10
3) Larger analyzing power
 δPTsyst ~ 0.1 δPTsyst (E246)
~ 10-4
1) Precise calibration of misalignments
2) Correction of systematic effects
3) Precise fwd-bwd cancellation
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

12. New Physics: Mode Predictions for PT
Model K+ → 0+ K+ → +
■ Standard Model < 10-7 < 10-7
■ Final State Interactions < 10-5 < 10-3
Multi-Higgs ≤ 10-3 ≤ 10-3
PT (K+ → 0+) ≈ + 3 PT (K+ → +)
SUSY with squark mixing ≤ 10-3 ≤ 10-3
PT (K+ → 0+) ≈ − 3 PT (K+ → +)
SUSY with R-parity breaking ≤ 4 x10-4 ≤ 3 x10-4
Leptoquark model ≤ 10-2 ≤ 5 x10-3
■ Left-Right symmetric model 0 < 7x10-3
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

13. The 3-Higgs Doublet Model
γ1
α1
M
ED
sγ
no
B→X τν
tr
b→
eu
•
N
c.f. dn , b→sγ ∝ Im(α1β1*), (α1β1*)
Im(α1β1*) _____ 2/v32 Im(γ1α1*)
= -v2 E246
Higgs field v.e.v.
 B→Xτν and B→τν at Super-Belle TREK goal
corresponds to PT < 3 x 10-4
c.f. TREK goal : PT ≤ 1 x 10-4 v2/v3 = mt / mτ
PT is most stringent constraint for Im(γ 1 α 1 *) !!
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

14. Lepton Flavour Universality
MSSM with charged-Higgs SUSY--LFV
N2 / Ne2 ~ 40,000 / 1
σp ~ 1 MeV/c
σt ~ 100 psec
New Pseudoscalar Interaction --
RK/RK = 0.2%
ΛeP ~ 750 TeV
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

15. e/ Identification – LFU
 Momentum measurement of e+, μ+
 TOF measurement between TOF1 and TOF2
 e+ trigger by aerogel Cherenkov detector.
β(e+ from Ke2) ~1
β(µ+ from K2) ~ 0.92 = 1 / 1.087
Estimated efficiency = 99.2 ± 0.2%
Fresnel mirror ⊗
beam
n=1.05
beam Target
PID performance and detector efficiency will be
measured & controlled using Ke3 and Kμ3 data.
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

16. TREK/E0 Tracking Upgrade
GEM technology --
In collaboration with
Jefferson Lab,
Hampton U. and MIT
70 µm holes
140 µm spacing
 Planar GEMs (C1)
between CsI and C2
 Cylindrical GEM (C0)
as replacement for old C1
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

17. The C0 Cylindrical GEM for TREK
300 mm
160 mm
140 mm
• Vertex tracking near target, δ < 0.1 mm
• Very high rate capability > 1 kHz/mm2
• Radiation-hardness >> 107
particles/mm2
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

18. R&D(1) – APD Readout for CsI(Tl)
• Improve the timing characteristics of
CsI(Tl) by replacing PIN diode with APD
• Pulse shaping and pile-up analysis
One-module energy One-module timing
new requirement too slow
•Both 1 and 9 module tests have been performed using an e+ beam at Tohoku
Univ. to check the energy resolution and high-rate performance of APD readout
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

19. R&D(2) – Active Muon Polarimeter
Top View
e+
μ+
μ+
 Full angular acceptance for positrons – 10x higher than in E-246
 Determination of decay vertex – background-free measurement
 Measurement of e+ angle and approx. energy – higher analyzing power
 Improved field alignment – suppressed systematic error
 Full-size prototype tested at TRIUMF in Nov. 2009
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

20. R&D(3) – Active Scintillating Fiber Target
One element Baseline design c.f. E246 Ring counters
PSI FAST target
Cross section
3 x 3 mm
492 fibres
 Light guide:
75 mm ϕ
Kuraray Y11 WLS fibre
 Readout:
SiPMT (Hamamatsu MPPC)
 Beam test using 130 MeV/c π’s
at TRIUMF – radiation damage
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

21. Upgrade Timeline
 Target:
 Finer segmentation of TGT scintillating fibres
Readout: MPPC (SiPMT) Hamamatsu
 Particle ID:
 Aerogel Cherenkov surrounding target, TOF LFU
 Charged particle tracking: 30 kW
 Add new element C1 between CsI(Tl) and C2 ~2013
 Add cylindrical GEM (C0) (remove aerogel)
TREK
 π 0 (1&2 photon) detection:
270 kW
 New, faster readout of CsI(Tl): APD, MAPD
 Wave form analysis using FADCs >100 kW
~2014
 Muon polarimeter :
 Active polarimeter with increased acceptance
 New muon holding field magnet with a parallel field
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

22. Summary
 TREK at J-PARC is gaining momentum
 “K1.1BR” secondary beamline has been commissioned
 Measurement of the T-violating transverse muon
polarization in Kμ3 decay (~2014)
- Large potential for the discovery of New Physics
- Upgrade of existing experimental setup of KEK E-246
 Measure Ke2/Kμ2 ratio to test lepton universality (~2013)
 Search for heavy neutrinos
- Use E-246 apparatus with
partial upgrades
New collaborators are welcome!
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

23. Thank You
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

24. J-PARC March11 Earthquake Damage
S. Bianchin PANIC 2011 (July 24th – 29th 2011)

25. S. Bianchin PANIC 2011 (July 24th – 29th 2011)

26. Lepton Universality in Kl2 and  l2 Decays
 Highly precise SM values
RKSM = ( 2.477 ± 0.001) x 10−5
RSM = (12.352 ± 0.004) x 10−5
 High sensitivity to LFV beyond SM
e.g. MSSM with charged-Higgs SUSY-LFV
RKLFV~ RKSM(1 ± 0.013)
 Current experimental precision ( NA62, KLOE )
RK = (2.488 ± 0.012) x 10−5, 1.1σ dev., RK/RK = 0.5% 0.4%
Improve precision to ~ 0.2%, presentation to PAC11
S. Bianchin PANIC 2011 (July 24th – 29th 2011)