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.