Status of Is the CKM matrix the only source of CP violation? Leo Bellantoni Fermilab Users' Meeting...
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Transcript of Status of Is the CKM matrix the only source of CP violation? Leo Bellantoni Fermilab Users' Meeting...
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%