4 th workshop on mass origin and susy march 6-8, 20061 k results: e949 steve kettell, bnl march 7...
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1 4th Workshop on Mass Origin and SUSY March 6-8, 2006
K Results: E949
Steve Kettell , BNL March 7th, 2006
Fourth Workshop on Mass Origin and Supersymmetry Physics
I. Motivation and Overview of K.II. Details of E949.III.Conclusions.
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 2
K Motivation
One of the Golden Modes for study of the CKM matrix and CP violation. The rate can be calculated precisely from fundamental SM parameters (~6%), and any deviation in the measured rate will be a clear signal for new physics.
1. FCNC, hard GIM suppression2. No long distance contribution3. Hadronic Matrix element from Ke3/isospin4. NNLO QCD calculation of c-quark cont.5. B(K) = (0.8±0.1)10-10
hep-ph/0508165
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 3
Motivation
VCKM=
Perhaps the most incisive test of the SM picture of CP violation is to verify K from A(Bd J/ψ Κs
o) & B(KL πονν)/B(K+π+νν)
Four very clean processes
Process Experiments
B(K+π+νν) E787/E949;E326,J-PARC?
B(K0π0νν) E391, KOPIO,J-PARC?
A(BJ/Ks0) BaBar, Belle
DMBs/DMBd LHCb
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 4
Worldwide Overview of K
E787: completed (1988-98); discovered two K events (DAR) E949: 2002 run; approved but not funded for 50 more weeks…(DAR) CKM: FNAL scientific approval; P5 says no (separated DIF) Kplus: FNAL LOI for unseparated DIF (rejected: not enough protons) LOI’s: J-PARC L-04 (DAR) and CERN E326 (unseparated DIF) E391a aims for 0.01-0.1 KL0 events; L-05 for 1000 events KOPIO construction start in 2005, aim for 100 KL0 events
E326
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 5
E787 K events
1998 Event1.75 100.82
B( ) 1.5
Branching Ra
7 1
o
0
ti
K x
PRL 88, 041803 (2002)
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 6
“PN
N1”
“PN
N2”
Outline of K Experimental Method Problem: 3-body decay (2 missing ’s); BR<10-10
Event signature = single K+ in, single + out Basic concepts
• Precise and redundant measurement of kinematics e.g. Energy (E) / Momentum (P) / Range (R)
or Velocity (V) / Momentum (P) / Range (R)
• PID: --e decay chain and/or P/R, P/V, dE/dx…
• Hermetic veto detectors () Major backgrounds
• K++ (Br=63%)• Kinematics (monochromatic)• PID: +/+
• K++0 (Br=21%)• Kinematics (monochromatic)• Photon veto
• Scattered beam particles• Timing• PID: K+/+
Primary signal region
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 7
E949 Experiment
V.V. Anisimovsky1,A.V. Artamonov2, B. Bassalleck3, B. Bhuyan4, E.W. Blackmore5, D.A. Bryman6, S. Chen5, I-H. Chiang4, I.-A. Christidi7,P.S. Cooper8, M.V. Diwan4, J.S. Frank4, T. Fujiwara9, J. Hu5, A.P. Ivashkin1, D.E. Jaffe4, S. Kabe10, S.H. Kettell4, M.M. Khabibullin1, A.N. Khotjantsev1, P. Kitching11, M. Kobayashi10, T.K. Komatsubara10, A. Konaka5, A.P. Kozhevnikov2, Yu.G. Kudenko1, A. Kushnirenko8, L.G. Landsberg2, B. Lewis3, K.K. Li4, L.S. Littenberg4, J.A. Macdonald5, J. Mildenberger5, O.V. Mineev1, M. Miyajima12, K. Mizouchi9, V.A. Mukhin2, N. Muramatsu13,T. Nakano13, M. Nomachi14, T. Nomura9, T. Numao5, V.F. Obraztsov2, K. Omata10, D.I. Patalakha2, S.V. Petrenko2, R. Poutissou5, E.J. Ramberg8, G. Redlinger4, T. Sato10, T. Sekiguchi10, T. Shinkawa15, R.C. Strand4, S. Sugimoto10, Y. Tamagawa12, R. Tschirhart8, T. Tsunemi10, D.V. Vavilov2, B. Viren4, N.V. Yershov1, Y. Yoshimura10 and T. Yoshioka10
1. Institute for Nuclear Research (INR), 2. Institute for High Energy Physics (IHEP),3. University of New Mexico (UNM), 4. Brookhaven National Laboratory (BNL), 5. TRIUMF, 6. University of British Columbia, 7. Stony Brook University, 8. Fermi National Accelerator Laboratory (FNAL),9. Kyoto University, 10. High Energy Accelerator Research Organization (KEK), 11. Centre for Subatomic Research, University of Alberta, 12. Fukui University, 13. Research Center for Nuclear Physics (RCNP), Osaka University,14. Osaka University, 15. National Defense Academy.
BNL/FNAL/SBU/UNM, U.S.AIHEP/INR, Russia Fukui/KEK/Kyoto/NDA/Osaka, Japan TRIUMF/UA/UBC, Canada
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 8
E949 Detector (1): Overview More protons from the AGS (High duty factor, high stopping fraction at low |p|)
Improved photon veto (Especially important for pnn2)
Improved tracking and energy resolution
Higher rate capability from FEE/trigger/DAQ upgrades (reduced deadtime)
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 9
K
Side view (cutaway) End view (top half)
E949 Detector (2): Details
• 700 MeV/c K+ beam (80%)• Active target (scintillation fibers) to stop K+
• Wait at least 2ns for K+ decay• Drift chamber to measure + momentum
• 19 layers of scintillator, Range Stack (RS) to measure E and R• Stop + in RS, waveform digitizer to record +-+-e+ decay chain• Veto photons, charged tracks over 4 (BV/BVL/Endcap/…)
New!
Renew inner 5 layers!Equip gain monitor!
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 10
Data Taking Conditions E787 collected NK=5.91012 in 81 weeks over 5 years. E949 proposed NK=181012 in 60 weeks over 3 years. E949 collected NK=1.81012 in 12 weeks in 2002. Beam conditions were less than optimal:
• broken separator – more + less K+
• spare M.G. – lower p+ mom., worse duty factor Detector worked very well Smooth data taking
E787 E949 Prop.
E949
AGS mom. GeV/c
25.5 25.5 21.9
Beam intensity Tp 15-35 65 70
Duty factor %
41-55 63 41
K+/p+ 3.7-4.2 4.0 3.0
NK 1012 5.9 18 1.8
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 11
Analysis StrategySignal region “the BOX”
Background sources
Analysis Strategy
(PNN1)region ππK Above 0
background Beam
),...)((K backgroundMuon
ππK 0
Blind Analysis Measure Background level with real data To avoid bias, 1/3 of data cut development 2/3 of data background measurement Characterize backgrounds using background functions Likelihood Analysis
Identify a priori. Identify at least 2 independent cuts to target each background K+
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 12
Calculation of backgrounds
Tag with
Tag kinematicsoutside box – in K peak
kinematics
Pho
ton
veto
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 13
Final Sensitivity and Background
E787 E949
NK (1012) 5.9 1.8 x 0.305
Acceptance (%) 0.20 0.02 0.22 0.02
x 1.1
Sensitivity (10-10) 0.83 2.6 x 0.336
Sensitivity
Background• 30% larger acceptance,
by enlarging the signalbox to lower edge ofE/P/R phase space,resulting in largerK2 backgrounds
All the cuts fixed and BG level estimated….
Source E787 E949
K2 0.032 0.216 0.023
K20.064
0.044 0.005
K, … 0.024 0.010
Beam 0.050 0.014 0.003
Total 0.14 0.05
0.298 0.026
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 14
Open the Box
Range vs. Energy after all other cuts are applied
Box shows signal region Single candidate in the box
Details
Momentum (MeV/c) 227.3
Range (cm) 39.2
Energy (MeV) 128.9
K++ decay time (ns) 4.3
++ decay time (ns) 6.2
+e+ decay time (ns) 1370
The 3rd K candidate
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 15
Branching ratio
CL) (68% 1096.0)( 1009.447.0
KBr
1030.189.0 1047.1)(
KBr
(68% CL)
E949(02) = combined E787&E949.E949 projection with full running period.
(~60 weeks)
E949 result alone:
Combine E787 and E949 results
E787 E949
NK (1012) 5.9 1.8
Candidate E787A E787C E949A
Si / bi 50 7 0.9
Wi=Si/(Si+bi) 0.98 0.88 0.48
BG Prob. 0.006 0.02 0.07
PRL 93, 031801 (2004)
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 16
Impact on Unitary Triangle Contour in - plane courtesy of J. Ocariz
Central value off the “SM” Need more data!!
K++
K++
K++
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 17
Further analysis: pnn2Further analysis: pnn2
More phase space than pnn1 Less loss from +N interactions Probe K spectrum
• Main background is K0 with
scatter in target – loss of R and P with photons aimed at weak part of detector
“PN
N1”
“PN
N2”
18
pnn2 analysis (2)pnn2 analysis (2)• Goal: sensitivity equal to pnn1, s/b = 1
2 acceptance and 5 rejection
• Improved PV: new detectors at small angles• Improved algorithms to identify π+ scatters in target
25
E787 Result:1996: PL B537, 211 (2002) 1997: PR D70, 037102 (2004)140<pp<195 MeV/c1 candidate event w/ expected background of 1.22 +/- 0.24 eventsBR(K++ ) < 22 x 10-10
Background limited, with S/N<0.2
E949 Data:E949 data is being worked on now – improved photon veto rejection will improve the limit and may allow observation of K signal.
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 19
0 rejection from real data (from pnn1 analysis.)
0 rejection from 1gammainefficiency tables.
Other PhysicsK (and K ) 0
(see talk by K. Mizouchi)
..and from E787:1. K+2. K+
PR D72, 091102(R) (2005)
PL B623, 192 (2005)
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 20
K Striking difference near the endpoint
between K w/UC vs. w/oUC Endpoint is interesting in K00 for
the CP-conserving contribution to K00l+l-
E787 observed 26 events with 100<P<180 MeV/c; good fit to c=1.80.6 w/UC and c=1.60.6 w/oUC.
B(K:100<P<180MeV/c)=(6.01.50.7)10-7
First run of E949 should see events near endpoint w/UC
Same analysis strategy and techniques as E787/E949 K
Bkg = 0.190.07
Acc = (3.720.14) 10-4 UC
Acc = (1.100.04) 10-4 w/oUC
No unitarity corrections
with unitarity corrections (UC)
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 21
K No events are observed. B(K:P>213MeV/c)<8.310-9 (UC)
B(K:P>213MeV/c)<2.310-8
Limit in this region is 8 better than E787
Need the rest of the scheduled E949 data for a definitive test of UC.
Same data is used to search for K (forbidden by angular momentum and gauge invariance), allowed in noncommutative theories
B(K) < 2.310-9
Limit is 150 better than E787All limits are (90% CL)
PL B623, 192 (2005)
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 22
Summary & Outlook (1)
E949 has observed a 3rd K event.
B(K++)=1.47 10-10
PRL 93 (2004) 031801
(SM: 0.8 10-10) BR remains higher than
expected…more data is needed! Lower Phase space region
accessible - results in 1-2 years with similar sensitivity (double E949 sensitivity).
Plans are underway to move the E949 detector to Japan
1.300.89
4th Workshop on Mass Origin and SUSY March 6-8, 2006 Steve Kettell, BNL 23
Summary & Outlook (2) K++ : while E949 remains un-
funded and CKM and Kplus were cancelled, E326 at CERN or a stopped J-PARC experiment look promising
KL0: while KOPIO has been cancelled, E391a has data and a future J-PARC experiment looks promising
It is clear that K remains an incisive test of the flavor structure of our physical world, whether described by the SM or new physics, and some combination of experiments should go forward!
Together K++ and KL0 provide a unique opportunity for discovery of new physics.
nextexpt.