Review

1

Review Outlook, Kaons Augusto Ceccucci/CERN

• Review
• KLOE (Frascati)
• Absolute Branching Ratios
• Kaon Lifetime
• Form-Factors
• NA48/2 (CERN)
• Search Direct CP-Violation in K
• Measurement of pp scattering length
• RKG(K ? e n) /G(K?mn)
• E391a (KEK)
• K0?p0 nn
• KTeV (Fermilab)
• Radiative decays

• Outlook
• DANAE
• JPARC
• K0L?p0 nn
• CERN-P-326 (NA48/3)
• K?p nn

Vus
2
KLOE_at_DAFNE Frascati

• e e- ? f ? K K- (K0S K0L)
• Advantages
• K0S and K0L tagging
• Measure of absolute BR
• Kaons have definite momentum
• Study of K0S and K0L semileptonic decays without
  ambiguities
• Low K momentum
• K0L and K lifetimes measurements can be done
  precisely

3
KLOE K0L Measurements
KL ? p0p0p0
hep-ex/0601038
K0L(e3)
Quadratic fit 1 l? t/mp 1/2 l??
(t/mp)2 l? (25.5 ? 1.5 ? 1.0) ? 10-3 l?? (
1.4 ? 0.7 ? 0.4) ? 10-3 Correlation r(l?,
l??) -0.95 Pole model fit MV 870(7) MeV
PLB626 (2005) 15

• ?BR(K0L) 1 ? ??KL) (50.72 ? 0.14 ? 0.33) ns
• BR(KL? ?e?(?) ) 0.4007 ? 0.0006stat ?
  0.0014syst
• BR(KL? ???(?) ) 0.2698 ? 0.0006stat ?
  0.0014syst
• BR(KL? 3??) 0.1997 ? 0.0005stat ? 0.0019syst
  
• BR(KL? ??????(?) ) 0.1263 ? 0.0005stat ?
  0.0011syst

tL 50.92 ? 0.17 ? 0.25 ns
Vosburgh et al. 72 tL 51.54 0.44 ns
PLB608(2005) 199
4
Vusf(0)
Only KLOE provides BR,tL f.f. (for IeK)
Blucher Marciano PDG 05
f(0)0.961/-0.008 Leutwyler Roos
5
NA48/2 (CERN-SPS)

• 2003 run 50 days
• 2004 run 60 days
• Total statistics in 2 years
• K?? ?? ? ?? 4109
• K?? ?0 ?0 ?? 2108
• 200 TB of data recorded

Beam pipe

• 400 GeV/c SPS protons
• 60 GeV/c secondary hadron beams
• Simultaneous collection
• of K and K- decays

6
Direct CP-violation in K/- ?p/- pp- K/-
?p/- p0p0
M(u,v)2 1 gu hu2 kv2
Lorentz-invariants u (s3-s0)/m?2 v
(s2-s1)/m?2 si (PK-P?i)2, i1,2,3 (3odd
?) s0 (s1s2s3)/3.

• Measured quantity sensitive to direct CP
  violation

Slope asymmetry Ag (g-g-)/(gg-)?0
Centre of mass frame u 2mK(mK/3-Eodd)/m?2 v
2mK(E1-E2)/m?2.
SM estimates vary within an order of magnitude
(few 10-68x10-5). Models beyond SM predict
substantial enhancement
7
Selected Statistics 2003
?M1.7 MeV/c2
Data-taking 2003 1.61x109 events selected
Events
V
even pion in beam pipe
????
K 1.03x109 events
odd pion in beam pipe
????
K? 0.58x109 events
U
8
Stability and Systematics
Systematic uncertainties Effect on ?x104
Acceptance and beam geometry 0.3
Spectrometer alignment 0.1
Analyzing magnet field 0.1
p??? decay 0.4
U calculation and fitting 0.2
Pile-up 0.2
Total systematics 0.6
Trigger efficiency L2 0.5
Trigger efficiency L1 0.4
Control of Detector asymmetry
Control of Beamline asymmetry
9
NA48/2 (2003 data)

• K/- ?p/- pp-
• Slope difference
• ?g (-0.70.9stat.0.6stat.(trig.)0.6syst.)x10-4
  
• (-0.71.0)x10-4
• Charge asymmetry
• Ag (1.72.1stat.1.4stat.(trig.)1.4syst.)x10-4
  
• (1.72.9)x10-4
• K/- ?p/- p0p0
• Slope difference
• ?g (2.3 2.8stat. 1.3trig.(stat.) 1.0syst.
  0.3ext.)x10-4
• (2.2 3.1)x10-4
• Charge asymmetry using g00.638
• A0g (1.8 2.2stat. 1.0trig.(stat.)
  0.8syst. 0.2ext.)x10-4
• (1.8 2.6)x10-4

hep-ex/0602014 PLB 634 (2006)
Order of magnitude improvement
10
Observation of p-p scattering effect in K?3p
decays
NA48/2 has made the first observation the of the
charge exchange process ?????0?0 in the
K???0?0?? decay.
1 bin 0.00015 GeV2
30M events

NA48/2 PLB 633 (2006) hep-ex/0511056
4mp2
K???0?0
4mp2
GM0M12
N. Cabibbo, hep-ph/0405001 PRL 93121801 (2004)
N. Cabibbo and G. Isidori, hep-ph/0502130 JHEP
503 (2005)
M2(?0?0) (GeV/c 2)2
11
Difference between p-p scattering length in I0
and I2 states
NA48/2 PLB 633 (2006) hep-ex/0511056
(a0 a2)m 0.268 0.010(stat) 0.004(syst)
0.013(theor)
In agreement with theory (a0 a2)m 0.265
0.004 (Colangelo 2001)
12
RKG(K ? e n) /G(K?mn)
NA48/2 EPS05
hep-ph/0511289
13
CKM Unitarity and Rare Kaon Decays
The unitarity of the CKM matrix can be
expressed by triangles in a complex plane.
There are six triangles but one is more
triangular
VudVubVcdVcbVtdVtb0 Wolfenstein
parameterization Vus l Vcb l2 A
Vub l3 A(r- ih) Vtd
l3 A(1-r- ih)

Sensitive to Vtd
SM BR(K?pnn) ? (1.610-5)Vcb4sh2(rc-r)2
? (8.0 1.1)10-11 BR(KL?p0nn) ?
(7.610-5)Vcb4h2 ? (3.0 0.6)10-11
Im lt A2 l5 h Re lt A2 l5 r
14
Reminder K?p nn
hep-ex/0403036 PRL93 (2004)
AGS
Stopped K 0.1 acceptance
BR(K ? p nn ) 1.471.30-0.89 10-10

15
K0L ? p0nn E391a Upper Limit

MggMp0
Require missing Pt

• 10 of RUN I
• Pencil beam
• Expected background
• from K0L decays 0.02
• Acceptance 0.73

BR(K0L ? p0nn )lt2.86?10-7 90CL Preliminary
(KAON2005) ?6 improvement over KTeV one day
special run ?2 improvement over published limit
(KTeV Dalitz technique)
16
Kaon Radiative Decays (KTeV, preliminary)

• K0L? pp-g
• gM1 1.198 /- 0.035 (stat) /- 0.086 (syst)
• a1/a2 -0.738 /- 0.007 (stat) /- 0.018 (syst)
• gE1 lt 0.21 (90 CL)
• BR(K0L ? p0p0g) lt 2.52 10-7 90CL
• BR(K0L ? penee-,Meegt5 MeV/c2)
• 1.606 /- 0.012(stat)0.026-0.016(syst)/
  -0.045(ext.) 10-5
• BR(p0? ee-,Xgt0.95)6.56/-0.26(stat) /-
  0.23(syst) 10-8
• K0L? ee-g
• BR(K0L? ee-g) 9.25 /- 0.03(stat) /-
  0.07(syst) /- 0.26 (ext) 10-6
• CaK -0.517 /- 0.030 (fit) /- 0.022 (syst)
• aDIP -1.729 /- 0.043(fit) /- 0.028(syst)
• BR(K0L? pp-p0g) 1.70 /- 0.03(stat)/-
  0.04(syst)) /- 0.03(norm) 10-4
• BR(K0L? pp-p0ee-,Eeegt20 MeV/c2) 1.60 /-
  0.18(stat) 10-7

17
OUTLOOK
18
DAFNE Luminosity and plans

• Last KLOE run 2006
• DAFNE runs until 2008 for other experiments
  FINUDA SIDDHARTA
• Plans for Luminosity and Energy upgrades (DANAE)

• DANAE Motivation
• Kaon interferometry
• Nuclear Physics
• N N form factor
• Synchrotron rad.
• RD

CM Energy (GeV) 1.02 2.4
Peak Luminosity (cm-2s-1) 1033 1032
19
Outlook K0L ? p0nn

• KOPIO _at_ BNL stopped
• In Japan a step by step approach is followed
• KEK
• E391a has completed data taking (three runs)
• They aim to reach the Grossman-Nir bound from the
  accumulated data
• J-PARC
• A proposal is being prepared for the new J-PARC
  hadron facility
• Step I move the E391a detector at J-PARC
• Step II build a new detector and a dedicated
  beamline to be able reach 100 SM events

20
E391a Expected sensitivity
KTeV Limit (Current Exp. Limit)
Single Event Sensitivity
From T. Inagaki
G-N Limit
1-day 1-week Run-I Run-II
Run-III
21
Outlook K0L?p0nn
From Taku Yamanaka
From Taku Yamanaka
22
Proposal to Measure the Rare Decay K?p n n at
the CERN SPS
CERN-SPSC-2005-013 SPSC-P-326

• CERN, Dubna, Ferrara,
• Florence, Frascati, Mainz,
• Merced, Moscow, Naples,
• Perugia, Protvino, Pisa,
• Rome, Saclay, San Luis Potosi,
• Sofia, Turin

23
Setting the bar for the next generation of
K?pnn experiments
E787/E949 BR(K ? p nn ) 1.471.30-0.89
10-10
Current constraint on r,h plane
?
100 events MeanSM
100 events MeanE787/949
24
P-326 Detector Layout
K?p n n
Gigatracker
p
K
11 MHz
n
75 GeV/c 800 MHz beam p/K/p
n
(KABES)
25
Background rejection

• 1) Kinematical Rejection
• 2) Photon vetoes and PID (p-m)
• Basic idea to reject K? pp0
• P(K) 75 GeV/c
• Require P(p) lt 35 GeV/c
• P(p0) gt 40 GeV/c It can be
• hardly missed in the calorimeters

Region I 0 lt m2miss lt 0.01 GeV2/c Region II
0.026 lt m2miss lt 0.068 GeV2/c4
26
Gigatracker

• Provide very good time resolution
• Minimise mass (multiple scattering and beam
  interactions)
• Sustain high, non-uniform rate ( 800 MHz total)

• Two Silicon micro-pixel detectors (SPIBES)
• Timing
• Pattern Recognition
• Improved KABES (micromegas TPC)
• To minimise scattering in the last station

SPIBES

• X/X0 ltlt 1
• Pixel size 300 x 300 mm
• s(p)/p 0.4
• excellent time resolution
• to select the right kaon track

Dependence of the signal to background (from K
?pp0 ) ratio as a function of the gigatracker
time resolution
26
27
LKr inefficiency measured with data
K ? p p0 collected by NA48 in 2004

p track and lower energy g are use to predict
the position of the other g
LKr ineff. per photon (Eg gt 10 GeV) h (2.8
1.1stat 2.3syst) 10-5 (prel.)
K?pp0p0
28
Signal backgrounds from K decays / year
Total Region I Region II
Signal (SM) 65 16 49
K?pp0 2.70.2 1.70.2 1.00.1
Km2 1.20.3 1.10.3 lt0.1
Ke4 22 negligible 22
K?ppp- and other 3-tracks bckg. 11 negligible 11
Kp2g 1.30.4 negligible 1.30.4
Km2g 0.40.1 0.20.1 0.20.1
Ke3, Km3 ,others negligible - -
Total bkg 93 3.00.2 63
Before taxes. Proposal quotes 40 evt/year
_at_BR10-10

• SPS used as LHC injector (so it will run in the
  future)
• No flagrant time overlap with CNGS
• P-326 fully compatible with the rest of CERN
  fixed target
• because P-326 needs only 1/20 of the SPS
  protons
• Beam time estimates based on decennial NA48
  experience at SPS

29
Status of P-326 (a.k.a. NA48/3)

• Presented at the CERN SPSC in September 2005
• RD endorsed by CERN Research Board on December
  2005
• Beam Test foreseen in August 2006
• Seeking more groups to join
• Aims to receive full approval by end of 2006.
• to be able to start data taking some time in
  2009-2010

30
Conclusions

• The last two years have been MIXED for kaon
  physics. On the one side there have been
  excellent results
• Vus Renaissence
• Precise bounds on Direct CP-Violation in charged
  kaon decays
• Progress on K0L ? p0nn
• Some surprises
• BUT on the other side
• All US-based future programmes have been stopped
  !!

Action is needed to keep KAONS at the heart of
Flavour Physics CP-Violation
31
SPARE SLIDES
32
Gigatracker (Hybrid Pixel)
G. Anelli, M. Scarpa, S. Tiuraniemi

• 200 mm Silicon sensor (gt11 000 e/h mip)
• Following Alice SPD
• Bump-bonding
• Read-out chip
• Pixel 300 mm x 300 mm
• Thinned down to 100 mm (Alice SPD 150 mm)
• Beam surface 14 cm2
• Adapted to the size of the SPIBES
• r-o chips
• 125 mm Cfibre for cooling support

Front End and R/O considerations based on the
experience of the CERN-PH/MIC and PH/ED Groups
with the ALICE SPD
MeV
33
Example hadronic cluster of a photon
Expected energy 29 GeV Deposited energy 9 GeV
Maximum energy 300 MeV
Expected g position

• Measured LKr inefficiency per photon (Eg gt 10
  GeV)
• h (2.8 1.1stat 2.3syst) 10-5
  (preliminary)

34
Acceptance equalisation for K and K-
Detector Left-Right asymmetry cancellation in
the 4 K/K ratios
? ? ? ?
Quadruple ratio
R(u) RUS(u)?RUJ(u)?RDS(u)?RDJ(u) (1 4 ?g u)
Cancellation of systematic biases - Detector
L-R asymmetries ( K ? Salève / K- ? Salève and
K ? Jura / K- ? Jura ) - Beam line biases (
K beam Up / K- beam Up and K beam Down / K-
beam Down) - Global time-variable biases
(K and K- simultaneously recorded)
Fit of R(u) is sensitive only to the time
variation of asymmetries in experimental
conditions with characteristic time smaller than
corresponding field alternation periods (beam?
week, detector? day) ? 2003 data taken in 4
SUPER-SAMPLES of 2 weeks each
35
RICH Layout
36
Downstream straw tracker

• 6 chambers with 4 double layers of straw tubes
  each (? 9.6 mm)
• Rate 45 KHz per tube (max 0.5 MHz) (mp)

2.3 m
Operate in high vacuum
Low X/X0
z
y
7.2 m
X/X0 0.1 per view
x
130 mm / hit s(P)/P 0.23 ? 0.005P s(q) 50
? 20 mrad
Good space resolution
7.2 m
Redundant momentum measurement
2 magnets 270 and 360 MeV Ptkick
5.4 m
8.8 m
5 cm radius beam holes displaced in the bending
plane according to the 75 GeV/c beam path
Veto for charged negative particles up to 60 GeV/c
37
P-326 Detector Layout
K?pp0
Gigatracker
p
g
K
11 MHz
g
75 GeV/c 800 MHz beam p/K/p
(KABES)
38
NA48 LKr as Photon Veto
Consolidation of the safety/control system and
read-out under way
39
Backgrounds not kinematically constrained
Decay BR
K?p0en (Ke3) 0.049
Km3 0.033
Km2g 5.510-3
K?pp0g 1.510-3
Ke4 410-5
Km4 110-5
They span accross the signal regions Must rely on
Particle ID and veto
8 of K decays
40
New high-intensity K beam for P-326
Already Available
Beam Present K12 (NA48/2) New HI K gt 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 (msterad) ? 0.40 ? 16 40
Av. Kmomentum ltpKgt (GeV/c) 60 75 K 1.5
Mom. band RMS (Dp/p in ) ? 4 ? 1 0.25
Area at Gigatracker (cm2) ? 7.0 ? 14 ? 2.0
Total beam per pulse (x 107) per Effective spill length MHz MHz/cm2 (gigatracker) 5.5 18 2.5 250 800 60 45 (27) 45 (27) 24(15)
Eff. running time / yr (pulses) 3 x 105 3 x 105 1.0
K decays per year 1.0x1011 4.8x1012 ? 48