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Rare Kaon Decays Review and Prospects. Augusto Ceccucci/CERN Physics State of the Art Prospects. s. d. XL th Rencontres de Moriond, EW Interactions and Unified Theories. n. n. Motivations. Search for explicit violation of Standard Model Lepton Flavour Violation (LFV) - PowerPoint PPT Presentation
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Moriond EW, March 10, 2005 A. Ceccucci, CERN 1
Rare Kaon Decays Review and Prospects
Augusto Ceccucci/CERN
•Physics•State of the Art •Prospects s d
XLth Rencontres de Moriond,EW Interactions and Unified Theories
Moriond EW, March 10, 2005 A. Ceccucci, CERN 2
Motivations
• Search for explicit violation of Standard Model – Lepton Flavour Violation (LFV)
• CP-Violation and Quark Mixing– Flavour Changing Neutral Currents (FCNC)– Unique probe of s → d transitions– Small theoretical errors [for some decays!]
• Other tests of fundamental symmetries– CP,CPT (e.g. KS→30 in G. Lanfranchi’s talk, KL→ee)
Moriond EW, March 10, 2005 A. Ceccucci, CERN 3
Lepton Flavour Violation
Moriond EW, March 10, 2005 A. Ceccucci, CERN 4
Puzzling replication of generations
|G|=1
→ e x x
-e conversion
| G| = 1| G| = 0
→ eee
x
x x
x
KL→e
K+→++e-
•Foreseen in many extensions of SM:
–Generation-Changing gauge interactions (Cahn, Harari (1980))
–Left-Right symmetry–Technicolor–Compositeness–Super-symmetry
Moriond EW, March 10, 2005 A. Ceccucci, CERN 5
K+ ++e-AGS – E865
~108 K+ /s~3 109part /pulse PK ~6 GeV/c
New Result based on 1998 data: hep-ph/0502020BR(K+ ++e-)< 2.2 10-11 (90%CL)Combined with previous results:BR(K+ ++e-)< 1.2 10-11 (90%CL)
Backgrounds (examples):K+→→eK+→ →+e+e-K+→→ e+e-Accidentals
8 Candidates consistent withexpected background of 8.2 ±1.9 Nsig <2.4
Moriond EW, March 10, 2005 A. Ceccucci, CERN 6
Lower bounds for generation-changing bosons (gX/gW~1)
Further progress on LFV (charged leptons) expected in muons
• →ePSI• N →e N MECO@AGS, J-PARC
>37 TeV/c2
>80 TeV/c2
>150 TeV/c2 0 12B( ) < 4.7 10LK e
11B( )<1.2 10K e
0 0 10B( ) 3.2 10LK eKTeV
E865
E871
4 4
0 2
( ) 116
( ) sinWX
W XC
MBr K e g
g MBr K
Moriond EW, March 10, 2005 A. Ceccucci, CERN 7
CP-Violation and Quark Mixing
Moriond EW, March 10, 2005 A. Ceccucci, CERN 8
CKM matrix and CP-Violation
'
'
'
ub
cb
td
ud us
cd cs
ts tb
V
V
V V
d d
s s
b b
V
V
V
V V
Ng=2 Nphase=0 No CP-Violation
Ng=3 Nphase=1 CP-Violation Possible
Quark mixing is described by the Cabibbo-Kobayashi-Maskawa (CKM) matrix
KM mechanism appears to be the main source of CP-violation in quarks:•Direct-CP Violation exists: ’/ 0 NA48, KTeV •CP violation in the B meson sector: ACP(J/ Ks), BaBar, Belle
Now look for inconsistencies in SM using independent observables affected by small theoretical uncertainties and different sensitivity to new physics
e.g. Im t= Im Vts*Vtd ≠ 0 CP
KM mechanism:
Moriond EW, March 10, 2005 A. Ceccucci, CERN 9
Kaon Rare Decays and the SM
(holy grail)
Kaons provide quantitative tests of SM independentfrom B mesons…
…and a large windowof opportunity exists!
|Vtd|
G. Isidori
Im t = A2 5 Re t = A2 5
Moriond EW, March 10, 2005 A. Ceccucci, CERN 10
K→ : Theory in Standard Model
2 2
5 5
20 0L L 5
Im Re Re( ) ( ) ( ) ( )
Im( ) ( )
t t ct t c
tt
B K X x X x P X
B K X x
charm
contributiontop
contributions
2 08
2 4
3 ( )
2 sinKW
Br K er
The Hadronic Matrix Element is measured and isospin rotated (~10% correction)
*
*
us
c cs cd
t ts td
VV VV V
Moriond EW, March 10, 2005 A. Ceccucci, CERN 11
Predictions in SM
11(latest CKM workshop)( ) (8.0 1.1) 10 BR K
Error ~ 14% Mainly parametricTheory error due to charm (Buras04):
( ) 0.389 0.033( ) 0.045( ) 0.010( )c c c sP X m Largest contributionfrom scale error. To bereduced by NNLOcalculation
0 0 11(Buras et al. 04)L( ) (3.0 0.6) 10 BR K
The error is almost purely parametric
Refer to Christopher Smith’s talkon long distance contributions
Moriond EW, March 10, 2005 A. Ceccucci, CERN 12
Possibly the Cleanest SM test
• In The phase derives from Z0 diagrams (S=1) whereas in A(J/ KS) originates in the box diagram (B=2)
• Any non-minimal contribution to Z0 diagrams would be signalled by a violation of the relation:
• A deviation from the predicted rates of SM would be a clear indication of new physics
• Complementary programme to the high energy frontier:– When new physics will appear at the Tevatron/LHC, the rare
decays may help to understand the nature of it
K
S/(sin 2 ) (sin 2 )K B J K
0 0d dB B
Moriond EW, March 10, 2005 A. Ceccucci, CERN 13
Some BSM Predictions
SM 8.0 ± 1.1 3.0 ± 0.6
MFVhep-ph/0310208
19.1 9.9
EEWPNP B697 133
7.5 ± 2.1 31 ± 10
EDSQhep-ph/0407021
15 10
MSSMhep-ph/0408142
40 50
0 0 11L( ) 10BR K 11( ) 10BR K
Compiled by S. Kettel
Moriond EW, March 10, 2005 A. Ceccucci, CERN 14
BR(KL ) 5.9 x 10-7 (0ee, 1997 Data) [PRD 61,072006 (2000)]
BR (KL ) 1.6 x 10-6 (0, 1997 1 Day) [PLB 447, 240 (1999)]
K0L State of the Art
DataMC BG Sumn MC MCSignal MC
KTeV 1997 Data Dalitz Analysis
Still far from the model independent limit: BR(K0 → 0) < 4.4 × BR(K++) ~ 1.4 × 10-9 Grossman & Nir, PL B407 (1997)
Moriond EW, March 10, 2005 A. Ceccucci, CERN 15
K+→+ : State of the art
BR(K+ → + ) = 1.47+1.30-0.89 × 10-10
•Compatible with SM within errors
hep-ex/0403036 PRL93 (2004)
Stopped K~0.1 % acceptance
AGS
Moriond EW, March 10, 2005 A. Ceccucci, CERN 16
Setting the bar for the next generation of K+→+ experiments
100 eventsMean=SM
100 eventsMean=E787/949
Current constraint on plane
?
Moriond EW, March 10, 2005 A. Ceccucci, CERN 17
0++, 2++
Direct CPV
Indirect CPV
(Measured by NA48/1 but
experimental error is
still large)
CPC
K0L→0ee and K0
L→0
Similar physics interest asK0
L→0 Complicatedby long distance contibutions and radiative backgrounds
I refer you to the talks by D. Greynat, C. Smith and L. Bellantoni
Moriond EW, March 10, 2005 A. Ceccucci, CERN 18
KTeV: KL→ 0ee
• One candidate in the signal box
• Combining 1997 and 1999:
1999 data
BR(KL → 0 ee ) < 3.5 × 10-10 @90%CL
BR(KL → 0 ee ) < 2.8 × 10-10 @90%CL
Expected Background 0.99 ± 0.35 events
PRL93, 021805 (2004)
Moriond EW, March 10, 2005 A. Ceccucci, CERN 19
KTeV: K0L
BR(K0L ) 3.8 10-10 (90% C.L.) [PRL 86, 5425 (2001)]
2 events in signal region
Background MC
Data
Moriond EW, March 10, 2005 A. Ceccucci, CERN 20
K0S →0 ee and K0
S →0
KS →0 eeKS →0
BR(KS→0ee) 10-9 = 5.8 +2.8
-2.3(stat) ± 0.8(syst)
|as|=1.06+0.26-0.21 (stat) ± 0.07 (syst)
PLB 576 (2003)
7 events, expected back. 0.15
BR(KS→0) 10-9 = 2.9 +1.4
-1.2(stat) ± 0.2(syst)
|as|=1.55+0.38-0.32 (stat) ± 0.05 (syst)
PLB 599 (2004)
6 events, expected back. 0.22
NA48/1 NA48/1
Moriond EW, March 10, 2005 A. Ceccucci, CERN 21
0 12L(K ) 10Br
0 12L( ) 10Br e e
Constructive
now favored by two independent analyses*
(Isidori, Unterdorfer, Smith,
EPJC36 (2004))
0 0L
0 0L
1.1 110.9
0.3 110.3
3.7 10
1.5 10
K e e
K
B
B
Destructive
0 0L
0 0L
0.7 110.6
0.2 110.2
1.7 10
1.0 10
K e e
K
B
B
*G. Buchalla, G. D’Ambrosio, G. Isidori, Nucl.Phys.B672,387 (2003)
*S. Friot, D. Greynat, E. de Rafael,
hep-ph/0404136, PL B 595*
K0L→0ee () in SM
Thank to the KS measurements, the KL BR can now be predicted* Interference between short- and long-distance physics*
Moriond EW, March 10, 2005 A. Ceccucci, CERN 22
Isidori, Unterdorfer, Smith:
Fleischer et al*:
Ratios of Bd → modes could be explained by enhanced electroweak penguins which, in turn, would enhance the KL BR’s:
•A. J. Buras, R. Fleischer, S. Recksiegel,
F. Schwab, hep-ph/0402112, NP B697 (2004)
0 0L
0 0L
1.6 111.6
0.7 110.7
9.0 10
4.3 10
NP
K e e
NP
K
B
B
0 12L(K ) 10Br
0 12L( ) 10Br e e
K0L→0ee (): Sensitivity to NP
~ SES of KTeVsearch
Moriond EW, March 10, 2005 A. Ceccucci, CERN 23
Prospects
• K0L
– Large window of opportunity exists.– Upper limit is 4 order of magnitude from the SM prediction– Expect results from data collected by E391a (proposed SES~3 10-10)– Next experiment KOPIO@ BNL
• K0L ee()
– Long distance contributions under better control– Measurement of KS modes has allowed SM prediction– KS rates to be better measured (KLOE?) – Background limited (study time dep. Interference?)– 100-fold increase in kaon flux to be envisaged
• K+ – The situation is different: 3 clean events are published– Experiment in agreement with SM– Next round of exp. need to collect O(100) events to be useful– Move from stopped to in flight experiments
Moriond EW, March 10, 2005 A. Ceccucci, CERN 24
KL→ E391a@PS-KEK
•First dedicated experiment to search for KL→ •Proposed SES~ 3 10-10
•Based on pencil kaon beam and photon vetoes•Collecting data now: waiting for resultsThis is a Stage I project for further study at J-PARC
Moriond EW, March 10, 2005 A. Ceccucci, CERN 25
KL→ KOPIO@BNL
•Proposed to collect 60 KL→ events with S/B~2 (Im t to 15%)•Measure as much as possible:
–Energy, Position and Angle for each photon•Work in the Kaon Center of Mass
–Micro-bunched AGS beam–Use TOF to measure KL momentum
•Start construction in 2005?
Moriond EW, March 10, 2005 A. Ceccucci, CERN 26
KOPIO@BNL
Status:Approved, Currently under cost reviewData Taking: 2011-?
Moriond EW, March 10, 2005 A. Ceccucci, CERN 27
Prospects on K+→+
• Decays at rest:– Window of opportunity to accumulate more data at BNL
until 2010 (before KOPIO data taking starts)– Ideas to pursue stopped kaon decays in Japan– Established technique…– …but hard to extrapolate to O(100) events
• Decays in flight– Large acceptances, good photon rejection– Separated beam: FNAL CKM (Approved but Not Ratified)
• Limited to about PK<30 GeV/c– Un-separated beam: CERN-NA48/3, FNAL-P940
• Limited by rate in beam trackers
Moriond EW, March 10, 2005 A. Ceccucci, CERN 28
NA48/3: SPSC-I229
• Collect 80 K+→+ events in about two years of data taking for:
– 4 1012 Kaon decays/SPS year– BR( K+→+ ~10-10
– Acceptance ~ 10%
– Absolute advantage:
High energy kaon beam: >35 GeV of EM energy deposited in the vetoes very difficult to miss 0 !!
– Disadvantage:
~1 GHz particle rate in beam tracker
Region I
P(K)=75 GeV/c
Region II
Moriond EW, March 10, 2005
A. Ceccucci, CERN 29
NA48/3 Detector Layout
800 MHz(/K/p)
Only the upstream detectors see the 800 MHz beam
10 MHz Kaon decays
K+ +
undetected
Moriond EW, March 10, 2005 A. Ceccucci, CERN 30
Acceptance
75 / 40 /
Assume Acceptance (Region I+II) ~ %KP GeV c P GeV c
( / )KP GeV c ( / )KP GeV c
Acceptance
Acceptance
Region I Region II
2 2 20 0.01 ( / )missm GeV c 2 2 20.026 0.068 ( / )missm GeV c
14 ( / ) 40P GeV c 14 ( / )P GeV c
14 ( / ) 30P GeV c
75 GeV/c
Moriond EW, March 10, 2005
A. Ceccucci, CERN 31
NA48/3 simulation
Uncorrelated non gaussian tails
Gaussian MSC (old)
Non-Gaussian MSC
P (Spectrometer 1) GeV/c P (Spectrometer 1) GeV/c
P (Spectrometer 2) GeV/c
P (Spectrometer 2)GeV/c
M(miss)2 (GeV/c2)2
New MSC
REGION I
REGION II
Moriond EW, March 10, 2005 A. Ceccucci, CERN 32
Beam:Present
K12(NA48/2)
New HI K+
> 2006
Factor wrt 2004
SPS protons per pulse on T10
1 x 1012 3 x 1012 3.0
Duty cycle (s./s.) 4.8 / 16.8 1.0
Solid angle (sterad) 0.40 16 40
Av. K+momentum <pK> (GeV/c)
60 75 Total : 1.35
Mom. band RMS: (p/p in %)
4 1 ~0.25
Area at Gigatracker (cm2) 7.0 20 2.8
Total beam per pulse (x 107)per Effective spill length MHz MHz/cm2 (gigatracker)
5.5182.5
25080040
~45 (~27)~45 (~27)~16 (~10)
Eff. running time / yr (pulses)
3x 105 3.1 * 105 1.0
K+ decays per year 1.0x1011 4.0x1012 40
New high-intensity K+ beam for NA48/3 AlreadyAvailable
John DaintonVillars 2004
October 7th 2004CERN seminar
SPSC@VillarsSPSC@Villars
● new rare decay frontier in K physics at CERN
● new experiments planned for Kπνν important
● support R&D now for K+π +νν results ≤ 2010
Moriond EW, March 10, 2005 A. Ceccucci, CERN 34
P940: Redesign of FNAL-CKM to useUnseparated beam
Moriond EW, March 10, 2005 A. Ceccucci, CERN 35
Conclusions
– Rare kaon decays studies are complementary to those performed at the energy frontier
– There are compelling physics cases that can be addressed with existing proton machines (SPS/MI/AGS)
– Technically challenging experiments but feasible
– Unique opportunity for you to join these efforts!
Moriond EW, March 10, 2005 A. Ceccucci, CERN 36
Back-up Slides
Moriond EW, March 10, 2005
A. Ceccucci, CERN 37
KKe3e3 KK22 ++00
S/B (hyp.)S/B (hyp.) 50 50 50
V V (hyp.)(hyp.) 5x108 (0) 5x106 () 5x108 (0)
AcceptanceAcceptance
(Flyo)(Flyo)2% (I)
12% (II)2.7% (I)13% (II)
0 (I)19% (II)
ResultResult ID < 1.5x103 (I)
1.1x103 (II)
V < 9x105
(I and II)
V < 0.2 (II)
Track Momentum: 15 – 35 GeV/c (RICH limited ?)
Signal Acceptance (Flyo estimation): 3.6% (Region I)
16% (Region II)
Legenda: V = Veto inefficiency (0 or )
Acceptance = Background acceptance (Regions I or II)
ID = Particle (electron-pion) separation inefficiency
V = Veto inefficiency of radiative photon
Formula:
or
signal signal
background V background ID V
A BR
A BR
S
B
Preliminary, G. Ruggiero
Moriond EW, March 10, 2005
A. Ceccucci, CERN 38
GIGATRACKER
• Specifications: – Momentum resolution to ~ 0.5 % – Angular resolution ~ 10 rad– Time resolution ~ 100 ps– Minimal material budget– Perform all of the above in
• 800 MHz hadron beam, 40 MHz / cm^2
• Hybrid Detector:– SPIBES (Fast Si micro-pixels)
• Momentum measurement • Facilitate pattern recognition in subsequent FTPC• Time coincidence with CHOD
– FTPC (NA48/2 KABES technology with FADC r/o)• Track direction
Moriond EW, March 10, 2005
A. Ceccucci, CERN 39
Recent lab test with 25 m gap
50 m gap 25 m gap
improvement of occupancy observed with 25m amplification gap
Width ~30 ns Width ~18
ns
KABES 25 micron amplification gap
Moriond EW, March 10, 2005
A. Ceccucci, CERN 40
KABES r/o with 480 MHz FADC
Moriond EW, March 10, 2005
A. Ceccucci, CERN 41
CompetitionNA48/3 P940
Accelerator CERN-SPS FNAL-MI
Energy (GeV) 400 120
Duty cycle (s /s ) 4.8 / 16.8 = 0.29 1.0 / 3.0 = 0.33
1 HEP year (s) 107 107
Eff. Spill. Length (s / s) 3.0 / 4.8 = 0.63 1.0 / 1.0 (?)
Total Rate (GHz) 0.8 0.23
Fraction of Kaons (%) 6 4
Flux of Kaons (MHz) 50 10
Decay fraction (%) 9 (50 m / 100 m) 17 (60 m / 67 m)
Acceptance (%) 10 5
Events/y (BR~10-10) 82 31