Slide 1

July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi1 A new proposal to measure O(100) events of K + + at the CERN SPS Riccardo Fantechi INFN - Sezione di Pisa On behalf of the P326 Collaboration CERN, Dubna, Ferrara, Firenze, Frascati, Mainz, Merced, Moscow, Napoli, Perugia, Protvino, Pisa, Roma, Saclay, Sofia, Torino _ Slide 2 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi2 Outline Physics motivations The goals The beam The detector Slide 3 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi3 Physics motivations K + + : process predicted with high accuracy Short distance only No EM penguins Matrix element derived from experiment (K + 0 e There is an intrinsic theoretical error of 5-7% on the amplitude, due to charm quark loops, which can be reduced to few % BR(K + + ) = (8.0 1.1) 10 11 in the SM @ NLO Constrain the CKM triangle only from the Kaon sector, together with future K 0 0 experiments _ _ _ Slide 4 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi4 Possibly the Cleanest SM test In the phase derives from Z 0 diagrams ( S=1) whereas in A(J/ K S ) originates in the box diagram ( B=2) Any non-minimal contribution to Z 0 diagrams would reflect on 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 LHC, the rare decays may help to understand the nature of it Slide 5 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi5 Some BSM Predictions SM8.0 1.1 MFV hep-ph/0310208 19.1 EEWP NP B697 133 7.5 2.1 EDSQ hep-ph/0407021 15 MSSM hep-ph/0408142 40 Slide 6 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi6 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 k, m d,sin(2 ) (All F=2 processes) 3 events from E949 100 events, SM100 events, E949 value _ _ Slide 7 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi7 Prospects on K + + Decays at rest: Window of opportunity to accumulate more data at BNL until 2010 (before KOPIO data taking starts) Letter of intent for an experiment with stopped kaon decays at JPARC (>2009) 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 P KSlide 8 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi8 P326 - The goal Collect 80 K + + events in about two years of data taking for: 4 10 12 Kaon decays/SPS year BR( K + + ~ 10 -10 Acceptance ~ 10% Decay in flight, unseparated beam Higher K momentum Larger yield of K decays Better veto performance Higher acceptance Different systematics Disadvantage: /K ratio ~ 10/1 1 Ghz rate in the beam tracker ahead of the decay volume Keep pions and pion decays inside a beam pipe Region I Region II K K K K K K K _ _ Slide 9 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi9 Background reduction Main background from K 2 and K + + 0 3 handles for background reduction: Missing mass cuts Photon vetoes Particle identification Redundant measurements to control the background Slide 10 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi10 Kinematics Measured quantities Resolution and MS tails for two and three body decays Cut on m 2 miss around mass and on m 2 miss >0 To have a S/N 10/1, need to cut at m 2 ~ 8 10 -3 GeV 2 /c 4 Need a resolution of ~ 10 -3 GeV 2 /c 4 On momentum July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi 13 Beam: Present K12 (NA48/2) New HI K + > 2006 Factor wrt 2004 SPS protons per pulse on T101 x 10 12 3 x 10 12 3.0 Duty cycle (s./s.)4.8 / 16.8 1.0 Solid angle ( sterad) 0.40 16 40 Av. K + momentum (GeV/c)6075 Total : 1.35 Mom. band RMS: ( p/p in %) 4 1 ~0.25 Area at Gigatracker (cm 2 ) 7.0 20 2.8 Total beam per pulse (x 10 7 ) per Effective spill length MHz MHz/cm 2 (gigatracker) 5.5 18 2.5 250 800 40 ~45 (~27) ~16 (~10) Eff. running time / yr (pulses)3* x 10 5 3.1 * 10 5 1.0 K + decays per year1.0x10 11 4.0x10 12 40 New high-intensity K + beam for NA48/3 Already Available Slide 14 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi 14 P326 Detector Layout 800 MHz ( /K/p) Only the upstream detectors Are exposed to the 800 MHz beam 10 MHz Kaon decays K+K+ ++ 1.5 m Slide 15 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi 15 Detectors CEDAR Differential Cherenkov counter for positive kaon identification GIGATRACKER To Track the beam before it enters the decay region ANTI Photon vetoes surrounding the decay tank SPECTROMETER 2 magnets + 6 straw chambers to track the kaon decay products RICH For redundant muon/pion separation CHOD Fast hodoscope to make a tight kaon-pion time coincidence (~100 ps) LKR Forward photon veto and e.m. calorimeter MAMUD Hadron calorimeter, muon veto and sweeping magnet SAC Small angle photon vetoes Challenging detector! Ineff. 10 -4 for E >100 Mev Ineff. 10 -5 for E > 1 Gev Ineff. 10 -6 for E > 6 Gev Ineff. 1 Gev 10 -3 electron inefficiency Get rid of the tails form MS Inefficiency: 10 -2 Inefficiency: 10 -5 Slide 16 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi 16 Gigatracker Challenging beam tracker ahead of the decay region 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, 60 MHz / cm 2 Hybrid Detector: SPIBES (Fast Si micro-pixels bonded to r/o ICs) Momentum measurement Facilitate pattern recognition in subsequent FTPC Time coincidence with CHOD FTPC (NA48/2 KABES micromegas technology with FADC r/o) Track direction Slide 17 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi 17 Time Schedule 2004 Parasitic tests in NA48/2 beam done Startup of working groups Submission of a Letter of Intent for the Villars meeting 2005 Gigatracker R&D started Preparation of the proposal Proposal submitted to SPSC Evaluation process for the proposal started 2006-2008 Costruction, Installation and beam-tests 2009-2010 Data Taking From the Villars report to the SPSC Slide 18 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi18 Conclusions An experiment to measure the decay in flight K + + is being proposed at CERN The goal is to collect O(100) events in 2 years The experiment will use some of the existing facilities of NA48 It is not definitely a continuation of NA48 There are new detectors with challenging aspects The Collaboration is being formed _ Slide 19 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi19 Spares Slide 20 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi20 Physics Introduction: CKM matrix and CP-Violation N g =2 N phase =0 No CP-Violation N g =3 N phase =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: A CP (J/ K s ), 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 V ts *V td 0 CP KM mechanism: Slide 21 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi21 Kaon Rare Decays and the SM (holy grail) Kaons provide quantitative tests of SM independent from B mesons and a large window of opportunity exists! |V td | G. Isidori Im t = A 2 5 Re t = A 2 5 Slide 22 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi22 K : Theory in Standard Model charm contribution top contributions The Hadronic Matrix Element is measured and isospin rotated (~10% correction) Slide 23 PI NU NU" By G. Isidori, C.Smith, F.Mescia. e-Print Archive: hep-ph/0503107"> July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi23 Predictions in SM Error ~ 14% Mainly parametric Theory error due to charm (Buras04): Largest contribution from scale error. To be reduced by NNLO calculation The error is almost purely parametric For long distance contribution see:"LIGHT-QUARK LOOPS IN K->PI NU NU" By G. Isidori, C.Smith, F.Mescia. e-Print Archive: hep-ph/0503107 Slide 24 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi24 BR(K L ) 5.9 x 10 -7 ( 0 ee , 1997 Data) [PRD 61,072006 (2000)] BR (K L ) 1.6 x 10 -6 ( 0 , 1997 1 Day) [PLB 447, 240 (1999)] K 0 L State of the Art Data MC BG Sum n MC MC Signal MC KTeV 1997 Data Dalitz Analysis Still far from the model independent limit: BR(K 0 0 ) < 4.4 BR(K + + ) ~ 1.4 10 -9 Grossman & Nir, PL B407 (1997) Slide 25 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi25 Prospects K 0 L 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 K 0 L ee( ) Long distance contributions under better control Measurement of K S modes by NA48/1 bound the K L measurement K S 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 Slide 26 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi 26 Message from the CERN Director General to the staff (Jan 05) The top priority is to maintain the goal of starting up the Large Hadron Collider (LHC) in 2007 Meanwhile, the natural break we have in the fixed-target programme in 2005 is already allowing the community to develop a well- focused programme for the future The possible Non-LHC Future Programme was reviewed by the SPSC in Villars (September 22-27, 2004) Slide 27 John Dainton Villars 2004 October 7th 2004 CERN seminar SPSC@Villars new rare decay frontier in K physics at CERN new experiments planned for K important support R&D now for K + + results 2010 Slide 28 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi 28 From the Villars Report CERN-SPSC-2005-010 SPSC-M-730 February 28, 2005 Slide 29 July 23rd, 2005HEPP - EPS 2005 Riccardo Fantechi29 Riduzione del background Taglio sulla m 2 miss intorno alla massa del 0 Inefficienza sui veti di 10 -8 Inefficienza sui di 5 10 -6 Rapporto S/N 10/1 con accettanza >1 Il taglio intorno alla massa del m 2 ~ 8 10 -3 GeV 2 /c 4 Risoluzione necessaria ~ 10 -3 GeV 2 /c 4 Risoluzione impulso K: 0.3% Risoluzione impulso