Statusof

Is the CKM matrix the only

source of CP violation?Leo BellantoniFermilab Users' MeetingJune 2002

220

24

tcb xXVRKBr

where

eKBrR

W

042

2

sin2

3901.0

22

21

02.007.040.10

(Buchalla & Buras, Falk et. al., D'Ambrosio and Isidori)

05.051.1 txX

Hadronic effects well understood

K+

K+

+

Compare B- D0 e- :HQET vs data

K+

0.79 0.10

<0.032

(BNL)

From fit by D'Ambrosio and Isidore, PL B530 (2002) 108 using above constraints, |Vub / Vcb|, K, and m(Bd)

K+

The CKM result in the event of no new physics

K+

In SUSY, branching ratio could be up to 210% (conceivably, much more) of the Standard Model value, leading to the above CKM result Buras,Colangelo,Isidori,Romanino,Silvestrini Nucl.Phys B566(2000)3.

K+

In MSSM, branching ratio could be between 65 to 102% the Standard Model value, leading to the above CKM result Buras,Gambino,Gorban,Jager,Silvestrini Nucl.Phys B592(2001)55.

K+

Buras et.al. found an "unlikely" SUSY scenario that gives enhancements of Br(K+

) up to 3x the SM level

Baek,Jang,Ko,Park, Nucl.Phys., B609(2001)442 also show a SUSY scenario where Br(K+

) differs markedlyfrom the SM level

Hattori,Hasuike,Wakaizumi, Nucl.Phys., B592(2001)55 also found large branching ratio enhancements in their 4 generation model

D'Ambrosio and Isidori, Phys.Lett., B530(2002)108 discusses the case wherenew physics has led us to draw the wrongconstraint from Bd mixing

BNL E787 reports 2 clean events

With recent (, values, expect

BNL E949 (upgrade of E787) expects to see 5 - 10 events using stopped K+

Run has started Needs 2 more years worth of data Joint collaboration with CKM (FNAL / BNL / IHEP)

CKM plans to see 100 events using the Main Injector and decay in flight

1075.182.0 1057.1)(

KBr

PRL 88, 041803 (2002)

K+

10

10

103.1

108.0)(

KBr

at 3 level,

Other Physics

•Lepton flavor violationK+ ++e- K+ +-e+

K+ -+e+ K+ -++

K+ -e+e+

•T violation in K+ 0l+

•Search for pseudoscaler in K+ e+

•Direct CP violation in 3,

•Form factors in K+ +l+l-

ppp

pppT

Detection

Fiducial region limited by beam energy,background from K, use of RICH tomeasure + velocity, need for K++ vertex

M2MISS = M2

K(1 - p/pK) + m2(1 - pK/p) – ppK2

100 events @ 17% x 1.6% x (8 x 10100 events @ 17% x 1.6% x (8 x 10-11-11)) Need ~4 x 10Need ~4 x 101414 K K++ ! !

Initial momentum-selectedbeam (+, p, K+) P/P ~ 2%

RF deflection: Asin(t) A ~ 15 MeV/c

Transport L = (integer)c /f t then integer multiple of 2 for +

2nd RF deflection e.g. 180o outof phase: -Asin(t+t)

For +, no net deflection For K+, deflection is 2A sin(n /K) cos(wt+ n /K)

Stop + with beam plug, collect K+

X

X

86.4

m12

.9 m

RF separated K+ beam

Turtle/GEANT simulation: Debunched 22GeV beam (+2%) 33MHz of K+ per 4 x 1012 ppp 71% Kaon purity Total charged particle rate into detector

<50MHz; muon component is 7.4MHz Achieves baseline CKM requirements

Need 5MeV/m P kick for 1sec spill need superconducting cavities to

create the deflection

RF separated K+ beam

RF separated K+ beam

Expressed as BMAX on inner Nb surface:This result: 104mTOur design @ 5MeV/m: 77mTTESLA @25 MeV/m: 110mTTESLA @35 MeV/m: 160mT

RF separated K+ beam

A recent 1-cell test result

Q

P (MeV/m)

Our Design Goal ThermalBreakdown

Have similar results on 2 other small structures, but still need to improve

(And have lots of tricks to try for that)

SURFT

RR0

0 lim

Detection

What We Want:

K++

What We'll Get:

K++

Br = 63.5%Also K++

K++

0(undetected)

Br = 21.2%

K++

X (undetected)

A

Kinematics

+ Veto

Veto

Charged VetoLow Material

Momentum,direction & position

of K+ and +

Detection

Redundant measurements essential

Tracking vs. RICHs

Straw Tubes

•Mechanical stress and leak rate testing2 x 10-7 atm-cc/sec-straw (N2)

•Fe55 source used to locate active region, wiresTypically 0.002" from nominal

•Ru106 source to measure drift times

20 straw prototypestesting in Lab 3

Photon Veto System

Small prototypes studied

2 sector (0.3%) prototype being

built now

Tagged e- beam test at Jlab Sept/Oct

20 layersscintillatorper PMT

4 PMTs persector in VVS

~4200 PMTsin entire vetosystem

We plan to explicitly test the factorizationhypothesis in an early special / engineering run

K+ 0+ Veto Test

We use the factorization to estimate the K+ 0+ background; i.e., we multiply overall 0 veto inefficiency of 1.6 x 10-7 by our kinematic rejection factor of 1/30000

BNL E787has testedfactorizationby plottingP(+) linein K+ +0

with (a) no veto cuts, (b)online vetocuts, (c) fullanalysis cuts

Electronics / DAQ

50MHz debunched beam need continuous deadtimeless digitization

TDC every (~30000) channel, QDC on , + vetos (~8000 channels)

Recent history of detector activity is important

Imagine 2 K++0 events 10ns PMT deadtime apart

K+

K+

+

+

(Branching Ratio)2 / (Number of veto channels)2

= 2 x 10-8 >> 8 x 10-11 Br we want to measure

Studying triggerless DAQ (just say yesand trigger at level 3 in software)

And at the end…

M2MISS = M2

K(1 - p/pK) + m2(1 - pK/p) – ppK2

Spares

Br(K+ ) = +{[ I(VtdVts

*) X(Mt/MW) ]2 CPV top loops

+[ R(VtdVts*) X(Mt/MW) CPC top loops

+R(VcdVcs*) P(Mt,s()) ]2}

Charm contribution; P = 0.42 0.06

+ =0.901

K+

32 Br(K+0e+)22 sin4W sin2C

Known to +2.5%

Charm contribution adds ~3% error in Br for any given I (VtdVts

*)

With current VCKM values

Br(K+ ) =(0.810.15)x10-11

(Hocker et.al., 2001)

(Buchalla & Buras)

RF separated K+ beam

Preliminary Specs

3.9 GHz, TM110 mode 15mm iris radius 47mm equator radius 38mm cell length

26 cells per meter 5 MeV/m Pkick; 15 MeV/station

Epeak= 19MV/m Bpeak= 77mT Transverse shunt impedance 702 /m Q x RSURF is 228 Stored energy 0.73 J/m 8.5 W/m dissipated into LHe 1.8 ~ 2.0 K Q: 2.2 x 109 (unloaded)

6.0 x 107 ( loaded )

Measuring the K+

UMS - high rate PWCs 2 stations of 6 planes each Rate 0.90 MHz/cm≲ 2 – compare

HyperCP rates of 0.75 MHz/cm2

K+ RICH - velocity spectrometer 10m long N2 radiator @ 1.1atmospheres

with ~10 detected photons 22GeV beam gives K+ resolution in () to

+0.5%

Measuring the +

20m long Ne RICH @ 1atmosphere:

Straw Tube tracker:

(total 13 layers)

K+, + RICHs

22GeV beam gives K+ resolution in () to +0.5%

K+ RICH is 10m long CF4 (or N2) radiator with ~10 detected photons

+ RICH is 20m long Ne radiator with 3000 PMTs

Challenges include: Need 02 contamination at O(10-6) Low mass mirrors High rate (~1MHz) photomultiplier

tubes Gaussian tails in resolution to 5

orders of magnitude Drawing heavily on the SELEX

experience

SELEX RICH

cm

Photon Veto System

Design assumes the demonstrated performanceof BNL-E787 system (1mm Pb / 5mm Scintillator)for vetoing low energy (20 - 200 MeV) photons

• angle and E() correlated in K++0

50% coverage

• E() > 1GeV in VVS +0 events critical

Online monitoring is crucial ~ Twoseconds of undetected dead time intwo years of data taking blows the

inefficiency budget

Photon Veto System

Small prototypes studied

2 sector (0.3%) prototype being built now

Tagged e- beam test at Jlab Sept/Oct

• Events with an E() > 1GeV in VVS have the enter at ~30 mrad angle

• GEANT simulation says 3 x 10-5 inefficiency can be achieved over 1GeV

• Photoproduction effects (e.g., Pb K0) in > 1GeV region: Total cross section ~4mBarn 4 x 10-5 inefficiency – but most of those final states will be detected

•Engineering problems are formidable!

+ Veto

Need to reject 14-20GeV + from K+2

decays at O (10-5) level

What could make a + fake a + ?• + bremsstrahlung• + e+• DIS

Tested a 26 layer (41mm Fe) / (10mm scintillator) 0.6 x0.6 meter prototype in Nov 2000 at IHEP(Protvino) with ~19GeV momentum analyzed + beam:

• 12 x 2 segmentation• After cuts on shower shape, acceptance (3~4) x10-6, with acceptance 75.3%• Corresponding GEANT numbers are 2 x10-6, 69%