April 12, 2006FPCP -- Vancouver1 Review –KLOE (Frascati) Absolute Branching Ratios Kaon Lifetime Form-Factors –NA48/2 (CERN) Search Direct CP-Violation in K ± Measurement of  scattering length R K =  (K   e  ) /  (K     –E391a (KEK) K 0 →   –KTeV (Fermilab) Radiative decays Outlook –DANAE –JPARC K 0 L →   –CERN-P-326 (NA48/3) K  →   Review & Outlook, Kaons Augusto Ceccucci/CERN V us

April 12, 2006FPCP -- Vancouver2  NE Frascati e  e -    K  K  (K 0 S K 0 L ) Advantages: –K 0 S and K 0 L tagging Measure of absolute BR –Kaons have definite momentum Study of K 0 S and K 0 L semileptonic decays without ambiguities – Low K momentum K 0 L and K + lifetimes measurements can be done precisely

April 12, 2006FPCP -- Vancouver3 KLOE K 0 L Measurements  BR(K 0 L ) =1   K L )= (50.72  0.14  0.33  ns BR(K L  e ) =  stat  syst BR(K L  ) =  stat  syst BR(K L  3   ) =  stat  syst BR(K L        ) =  stat  syst L/  c (ns) ns cm 0.37 L × 10 2 Events/0.3 ns P K = 110 MeV Quadratic fit: 1   t/m     t/m   2  = (25.5  1.5  1.0)  10  3   = ( 1.4  0.7  0.4)  10  3 Correlation:  ( ,  ) =  0.95 Pole model fit: M V = 870(7) MeV hep-ex/  L =  0.17  0.25 ns PLB626 (2005) 15 KL  KL   PLB608(2005) 199 K 0 L (e3) Vosburgh et al. ’72:  L = ± 0.44 ns

April 12, 2006FPCP -- Vancouver4 |V us |f + (0) Blucher & Marciano PDG 05 f + (0)=0.961+/ Leutwyler & Roos Only KLOE provides BR,  L & f.f. (for I e K )

April 12, 2006FPCP -- Vancouver5 NA48/2 (CERN-SPS) Beam pipe 2003 run: ~ 50 days 2004 run: ~ 60 days Total statistics in 2 years: K      +   : ~4·10 9 K      +   : ~4·10 9 K    0  0   : ~2·10 8 K    0  0   : ~2·10 8 ~ 200 TB of data recorded 400 GeV/c SPS protons 60 GeV/c secondary hadron beams Simultaneous collection of K + and K - decays

April 12, 2006FPCP -- Vancouver6 Direct CP-violation in K        K        |M(u,v)| 2 ~ 1 + gu + hu 2 + kv 2 Centre of mass frame u = 2m K ∙(m K /3-E odd )/m  2 ; v = 2m K ∙(E 1 -E 2 )/m  2. Measured quantity sensitive to direct CP violation: Slope asymmetry: A g = (g + -g - )/(g + +g - )≠0 Lorentz-invariants u = (s 3 -s 0 )/m  2 ; v = (s 2 -s 1 )/m  2 ; s i = (P K -P  i ) 2, i=1,2,3 (3=odd  ); s 0 = (s 1 +s 2 +s 3 )/3. SM estimates vary within an order of magnitude few …8x10 -5 (few …8x10 -5 ). Models beyond SM predict substantial enhancement

April 12, 2006FPCP -- Vancouver7 Selected Statistics 2003 U |V| even pion in beam pipe Data-taking 2003: 1.61x x10 9 events selected K + : 1.03x10 9 events K  : 0.58x10 9 events  odd pion in beam pipe  M =1.7 MeV/c 2 Events

April 12, 2006FPCP -- Vancouver8 Stability and Systematics Systematic uncertainties Effect on Δx10 4 Acceptance and beam geometry 0.3 Spectrometer alignment0.1 Analyzing magnet field0.1 π ±  decay 0.4 U calculation and fitting0.2 Pile-up0.2 Total systematics0.6 Trigger efficiency: L20.5 Trigger efficiency: L10.4 Control of Detector asymmetry Control of Beamline asymmetry Jura Jura(Left) A+ A- Salève(Right) Z XY Achromats: K + Up Achromats: K + Down B+ B-B-B-B-

April 12, 2006FPCP -- Vancouver9 NA48/2 (2003 data) K        Slope difference: Δg = (-0.7±0.9 stat. ±0.6 stat.(trig.) ±0.6 syst. )x10 -4 = (-0.7±1.0)x10 -4 Charge asymmetry: A g = (1.7±2.1 stat. ±1.4 stat.(trig.) ±1.4 syst. )x10 -4 = (1.7±2.9)x10 -4 K        Slope difference: Δg = (2.3 ± 2.8 stat. ± 1.3 trig.(stat.) ± 1.0 syst. ± 0.3 ext. )x10 -4 = (2.2 ± 3.1)x10 -4 Charge asymmetry: Charge asymmetry: [using g 0 =0.638 ] A 0 g = (1.8 ± 2.2 stat. ± 1.0 trig.(stat.) ± 0.8 syst. ± 0.2 ext. )x10 -4 = (1.8 ± 2.6)x10 -4 hep-ex/ ; PLB 634 (2006) Order of magnitude improvement

April 12, 2006FPCP -- Vancouver10 Observation of  scattering effect in K→3  decays 1 bin = GeV 2 K ±  ±  0  0 4m π M events 4m π + 2 NA48/2 has made the first observation the of the charge exchange process  +    0  0 in the K   0  0   decay. M 2 (  0  0 ) (GeV/c 2 ) 2 NA48/2 PLB 633 (2006) hep-ex/ N. Cabibbo, hep-ph/ PRL (2004) N. Cabibbo and G. Isidori, hep-ph/ JHEP 503 (2005)  ~|M 0 +M 1 | 2

April 12, 2006FPCP -- Vancouver11 Difference between  scattering length in I=0 and I=2 states (a 0 – a 2 )m + = ± 0.010(stat) ± 0.004(syst) ± 0.013(theor) In agreement with theory (a 0 – a 2 )m + = ± (Colangelo 2001) NA48/2 PLB 633 (2006) hep-ex/

April 12, 2006FPCP -- Vancouver12 hep-ph/ NA48/2 EPS05 R K =  (K   e  ) /  (K    

April 12, 2006FPCP -- Vancouver13 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”: V ud V ub *+V cd V cb *+V td V tb *=0 Wolfenstein parameterization: V us ~ V cb ~   V ub ~   i  V td ~   i  Sensitive to |V td | Im t =  2 5  Re t =  2 5  SM: BR(K +  + )  (1.6×10 -5 )|V cb | 4 [  2 +(  c -  ) 2 ]  (8.0 ± 1.1)× (1.6×10 -5 )|V cb | 4 [  2 +(  c -  ) 2 ]  (8.0 ± 1.1)× BR(K L  0 )  (7.6×10 -5 )|V cb | 4  2  ± 0.6  ×10 -11

April 12, 2006FPCP -- Vancouver14 Reminder: K + →  + BR(K + →  + ) = × hep-ex/ PRL93 (2004) Stopped K + ~0.1 % acceptance AGS

April 12, 2006FPCP -- Vancouver15 K 0 L     E391a Upper Limit BR(K 0 L    )<2.86  %CL Preliminary (KAON2005)  6 improvement over KTeV one day special run  2 improvement over published limit (KTeV Dalitz technique) 10% of RUN I Pencil beam Expected background from K 0 L decays: 0.02 Acceptance: 0.73% M  =M   Require missing Pt

April 12, 2006FPCP -- Vancouver16 Kaon Radiative Decays (KTeV, preliminary) K 0 L       –g M1 = / (stat) +/ (syst) –a 1 /a 2 = / (stat) +/ (syst) –g E1 < 0.21 (90% CL) BR(K 0 L       ) < %CL BR(K 0 L   e e  e ,M ee >5 MeV/c 2 ) = / (stat) (syst)+/-0.045(ext.) BR(    e  e ,X>0.95)=6.56+/-0.26(stat) +/- 0.23(syst) K 0 L  e  e   –BR(K 0 L  e  e   ) = /- 0.03(stat) +/- 0.07(syst) +/ (ext) –C  K* = / (fit) +/ (syst) –  DIP = / (fit) +/ (syst) BR(K 0 L         ) = /- 0.03(stat)+/- 0.04(syst)) +/- 0.03(norm) BR(K 0 L        e  e ,E ee >20 MeV/c 2 ) = /- 0.18(stat) 10 -7

April 12, 2006FPCP -- Vancouver17 OUTLOOK

April 12, 2006FPCP -- Vancouver18 DA  NE Luminosity and plans Last KLOE run: 2006 DA  NE runs until 2008 for other experiments: FINUDA +SIDDHARTA Plans for Luminosity and Energy upgrades (DANAE) CM Energy (GeV) Peak Luminosity (cm -2 s -1 ) DANAE Motivation: Kaon interferometry Nuclear Physics N N form factor Synchrotron rad. R&D

April 12, 2006FPCP -- Vancouver19 Outlook: K 0 L    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

April 12, 2006FPCP -- Vancouver20 E391a Expected sensitivity 1-day 1-week Run-I Run-II Run-III Single Event Sensitivity G-N Limit KTeV Limit (Current Exp. Limit) From: T. Inagaki

April 12, 2006FPCP -- Vancouver21 From Taku Yamanaka Outlook: K 0 L →  0 From Taku Yamanaka

April 12, 2006FPCP -- Vancouver22 Proposal to Measure the Rare Decay K     at the CERN SPS CERN, Dubna, Ferrara, Florence, Frascati, Mainz, Merced, Moscow, Naples, Perugia, Protvino, Pisa, Rome, Saclay, San Luis Potosi, Sofia, Turin CERN-SPSC SPSC-P-326

April 12, 2006FPCP -- Vancouver23 Setting the bar for the next generation of K + →  + experiments 100 events Mean=SM 100 events Mean=E787/949 Current constraint on  plane ? E787/E949: BR(K + →  + ) = ×

April 12, 2006FPCP -- Vancouver24 P-326 Detector Layout 75 GeV/c 800 MHz beam  /K/p K+K+ ++ ~11 MHz Gigatracker (KABES) K    

April 12, 2006 FPCP -- Vancouver 25 Background rejection 1) Kinematical Rejection 2) Photon vetoes and PID (  ) Basic idea to reject K +  +  0 : P(K  ) = 75 GeV/c Require P(   ) < 35 GeV/c P(   ) > 40  GeV/c It can be hardly missed in the calorimeters Region I: 0 < m 2 miss < 0.01 GeV 2 /c Region II: < m 2 miss < GeV 2 /c 4

April 12, 2006FPCP -- Vancouver26 Gigatracker 26 X/X 0 << 1% Pixel size ~ 300 x 300  m  (p)/p ~ 0.4% excellent time resolution to select the right kaon track Provide very good time resolution Minimise mass (multiple scattering and beam interactions) Sustain high, non-uniform rate ( 800 MHz total) PP PKPK   Two Silicon micro-pixel detectors (SPIBES) Timing Pattern Recognition Improved KABES (micromegas TPC) To minimise scattering in the last station SPIBES: Dependence of the signal to background (from K +      ) ratio as a function of the gigatracker time resolution

April 12, 2006FPCP -- Vancouver27 LKr inefficiency measured with data Cluster not reconstructed E  = 22 GeV Pion P=42 GeV/c Photon E=11 GeV Expected position K +      collected by NA48 in 2004   track and lower energy  are use to predict the position of the other  +00+00 LKr ineff. per photon (E  > 10 GeV):   = (2.8 ± 1.1 stat ± 2.3 syst ) × (prel.)

April 12, 2006 FPCP -- Vancouver 28 Signal & backgrounds from K decays / year* TotalRegion IRegion II Signal (SM) K++0K++0 2.7±0.21.7±0.21.0±0.1 K2K2 1.2±0.31.1±0.3<0.1 K e4 2±2negligible2±2 K   +  +   and other 3-tracks bckg. 1±1negligible1±1 22 1.3±0.4negligible1.3±0.4 K2K2 0.4±0.10.2±0.1 K e3, K  3,othersnegligible  Total bkg9±33.0±0.26±3 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 * Before taxes. Proposal quotes

April 12, 2006FPCP -- Vancouver29 Status of P-326 (a.k.a. NA48/3) Presented at the CERN SPSC in September 2005 R&D 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

April 12, 2006FPCP -- Vancouver30 Action is needed to keep KAONS at the heart of Flavour Physics & CP-Violation Conclusions The last two years have been MIXED for kaon physics. On the one side there have been excellent results: –V us Renaissence –Precise bounds on Direct CP-Violation in charged kaon decays –Progress on K 0 L    –Some surprises BUT on the other side: –All US-based future programmes have been stopped !!

April 12, 2006FPCP -- Vancouver31 SPARE SLIDES

April 12, 2006FPCP -- Vancouver32 Gigatracker (Hybrid Pixel) 200  m Silicon sensor (> e/h mip) –Following Alice SPD –Bump-bonding Read-out chip –Pixel 300  m x 300  m –Thinned down to ~100  m (Alice SPD 150  m) Beam surface ~ 14 cm 2 –Adapted to the size of the SPIBES r-o chips ~125  m Cfibre for cooling & support y x 2mm/bin Station 1(pixels) 2(pixels) 3(FTPC) G. Anelli, M. Scarpa, S. Tiuraniemi Front End and R/O considerations based on the experience of the CERN-PH/MIC and PH/ED Groups with the ALICE SPD MeV

April 12, 2006FPCP -- Vancouver33 Example: “hadronic” cluster of a photon Expected  position Maximum energy ~300 MeV Expected energy: ~29 GeV Deposited energy: ~9 GeV Measured LKr inefficiency per photon (E g > 10 GeV):  = (2.8 ± 1.1 stat ± 2.3 syst ) × (preliminary)

April 12, 2006FPCP -- Vancouver34 Acceptance equalisation for K + and K - Detector Left-Right asymmetry cancellation in the 4 K + /K ­ ratios: ♦♦♦♦♦♦♦♦ R(u) = R US (u)  R UJ (u)  R DS (u)  R DJ (u) = (1 + 4 Δg u) 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 Quadruple ratio: 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) Jura Jura(Left) A+ A- Salève(Right) Z XY Achromats: K + Up Achromats: K + Down B+ B-B-B-B-

April 12, 2006FPCP -- Vancouver35 RICH Layout

April 12, 2006 FPCP -- Vancouver 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) (  +  ) Low X/X 0 Operate in high vacuum X/X 0 ~ 0.1% per view Good space resolution 130  m / hit  (P)/P = 0.23%  0.005%P  (  ) ~ 50  20  rad Redundant momentum measurement 2 magnets: 270 and 360 MeV P t kick 8.8 m 7.2 m 5.4 m Veto for charged negative particles up to 60 GeV/c 5 cm radius beam holes displaced in the bending plane according to the 75 GeV/c beam path z x y 2.3 m

April 12, 2006FPCP -- Vancouver37 P-326 Detector Layout 75 GeV/c 800 MHz beam  /K/p K+K+ ++   ~11 MHz Gigatracker (KABES) KK

April 12, 2006FPCP -- Vancouver38 NA48 LKr as Photon Veto Energy of photons from K       hitting LKr: > 1 GeV GeV Consolidation of the safety/control system and read-out under way

April 12, 2006 FPCP -- Vancouver 39 Backgrounds not kinematically constrained Decay BR K +  0 e + (K e3 ) K3K3K3K K2K2K2K2 5.5×10 -3 +0K++0+0K++0 1.5×10 -3 K e4 4×10 -5 K4K4K4K4 1× % of K + decays They span accross the signal regions Must rely on Particle ID and veto

April 12, 2006FPCP -- Vancouver40 Beam: Present K12 (NA48/2) New HI K + > 2006 Factor wrt 2004 SPS protons per pulse on T101 x x Duty cycle (s./s.)4.8 / Solid angle (  sterad)  0.40  Av. K + momentum (GeV/c)6075 K + ~ 1.5 Mom. band RMS: (  p/p in %)  4  1 ~0.25 Area at Gigatracker (cm 2 )  7.0  14  2.0 Total beam per pulse (x 10 7 ) per Effective spill length MHz MHz/cm 2 (gigatracker) ~45 (~27) ~24(~15) Eff. running time / yr (pulses)3 x K + decays per year1.0x x10 12  48 New high-intensity K + beam for P-326 Already Available