rare kaon decays: opportunities at cern

Download Rare Kaon Decays:  Opportunities at CERN

Post on 03-Feb-2016

43 views

Category:

Documents

0 download

Embed Size (px)

DESCRIPTION

Rare Kaon Decays: Opportunities at CERN. Augusto Ceccucci/CERN Padova, January 18, 2005. Why study Rare Kaon Decays In the 21 st century?. Search for explicit violation of Standard Model Lepton Flavour Violation Study the strong interactions at low energy - PowerPoint PPT Presentation

TRANSCRIPT

  • Rare Kaon Decays: Opportunities at CERNAugusto Ceccucci/CERN Padova, January 18, 2005

    A. Ceccucci, CERN

  • Why study Rare Kaon DecaysIn the 21st century?Search for explicit violation of Standard Model Lepton Flavour ViolationStudy the strong interactions at low energy Chiral Perturbation Theory, Form FactorsTest fundamental symmetriesCP,CPT Probe the flavour sector of the Standard ModelFCNCUnique probe of the sd quark transitionssdVtdVts*

    A. Ceccucci, CERN

  • Quark mixing and CP-Violation Ng=2 Nphase=0 No CP-Violation

    Ng=3 Nphase=1 CP-Violation PossibleQuark mixing is described by the Cabibbo-Kobayashi-Maskawa (CKM) matrixPredictions of standard theory (after KM ): Direct-CP Violation exists: e/e 0 NA48, KTeV CP violation in the B meson sector: ACP(J/y Ks), BaBar, Belle

    Paradigm shift: having established the abovelook for inconsistencies in SM using observables with small theoretical errors

    Im lt= Im Vts*Vtd 0

    A. Ceccucci, CERN

  • 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. IsidoriIm lt = A2 l5 h Re lt = A2 l5 r

    A. Ceccucci, CERN

  • Further Enticement: New Physics?These rare kaon decays are second order weak interactions mediated by Z penguins that could be sensitive to NPA deviation from the predicted rates of SM would be a clear indication of new physicsComplementary programme to the high energy frontier:When/if new physics will appear at the LHC, the rare decays may help to understand the nature of it

    A. Ceccucci, CERN

  • Kaons@CERN:NA4819962004

    NA48/2: K

    Re e/e = 14.7 2.2 10-4First observation ofK0S p0 e+e- and K0S p0 m+m-Ave: Re e/e = 16.7 2.3 10-4

    + KL Rare DecaysSearch for Direct CP-Violation in charged kaon decaysDirect CP-Violation established!

    A. Ceccucci, CERN

  • NA48 Vacuum Tank

    A. Ceccucci, CERN

  • NA48 Detector 1996Total: 5.3M KL00Magnetic spectrometerLiquid krypton EM calorimeter

    90 m longVacuum tank400 GeV protonsFrom CERN SPS

    A. Ceccucci, CERN

  • Recent but well established Rare Kaon Decay Tradition @CERN:NA48/1

    A. Ceccucci, CERN

  • 0++, 2++Direct CPV Indirect CPVCPC NA48/1: K0sp0e+e- and K0sp0m+m-Principal aim of NA48/1: Measure the IndirectCP-Violating Contributionto K0Lp0e+e- and K0Lp0m+m-

    A. Ceccucci, CERN

  • NA48/1: Backgrounds

    Many other sources investigated and found to be negligible (e,g neutral cascade decays)

    Blind analysis: Control and signal region remained masked until the study of the background was finished

    A. Ceccucci, CERN

  • K0S p0 e+e- and K0S p0 m+m- KS p0 eeKS p0 mmBR(KSp0ee) 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. 0.15BR(KSp0mm) 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. 0.22NA48/1NA48/1M. Patel PhD thesisM. Slater PhD thesis

    A. Ceccucci, CERN

  • Isidori, Unterdorfer,Smith:Fleischer et al*: Ratios of Bd Kp modes could be explained by enhanced electroweak penguins which, in turn, would enhance the KL BRs:A. J. Buras, R. Fleischer, S. Recksiegel, F. Schwab, hep-ph/0402112, NP B697 (2004)K0Lp0ee (mm): Sensitivity to NP

    A. Ceccucci, CERN

  • NA48/1: Semileptonic X0 decaysS+X0 semileptonic decay is the only source of S+ in the neutral beam becauseX0S+ p- is kinematically forbidden

    A. Ceccucci, CERN

  • Preliminary ResultBased on 6238 X0 b-decays:BR(X0 S+ e- n)=(2.51 0.03sta 0.11sys)10-4Compare KTeV: (2.71 0.38) 10-4 Systematics: Trigger Efficiency 2.6 % Acceptance 3.0 % X0 ff (g1 and f2) 1.0 % X0 Polarisation 1.0 % X0 Lifetime 0.5 % Tot systematics 4.2 % Stat Uncertainty 1.2 %

    A. Ceccucci, CERN

  • NA48/2 : K+/K- Simultaneous K+ and K- beams

    A. Ceccucci, CERN

  • NA48/2: Aim Direct CP violation in K , K 0 0 M(u) 1 + gu, u= f( )

    (Ag ) < 210 4 g + - g -Ag = g+ + g -In addition: Study of pp scattering using Ke4 (and pp0p0) events Study of medium-rare charged kaon decays Study of semi-leptonic decays

    A. Ceccucci, CERN

  • K+-e (Ke4) selection (preliminary)Cabibbo-Maksymowicz variables [backgr. in red]2003 data: > 500k (background ~0.6%)

    A. Ceccucci, CERN

  • First Observation of the + - - rescatteringin K 0 0 decaysM2(00), (GeV/c2)229M decaysNA48/2 Preview!

    A. Ceccucci, CERN

  • Determination of a0-a2 from K 0 0 decaysN. Cabibbo hep-ph 0405001, PRL93 (2004)

    A. Ceccucci, CERN

  • Ke+e- & K+- selection(preliminary)Z=(M(ee)/MK)2Form-factorK e+e-> 2600ev.M( e+e-), GeV/c2 low background (1-2%)

    expected data sample in 2003-2004 comparable to the World best sampleNA48/2(2003)

    A. Ceccucci, CERN

  • CERN Director General Outlines Seven-point Strategy for European Laboratory 18.6.2004 Official CERN Press Release Geneva 18 June 2004. At the 128th session of CERN Council, held today under the chairmanship of Professor Enzo Iarocci, CERN Director General, Robert Aymar, outlined a seven-point scientific strategy for the Organization. Top of the list was completion of the Large Hadron Collider (LHC) project with start-up on schedule in 2007. This was followed by consolidation of existing infrastructure at CERN to guarantee reliable operation of the LHC, with the third priority being an examination of a possible future experimental programme apart from the LHC. The possible Future Programme was reviewed by the SPSC in Villars (September 22-27, 2004)

    A. Ceccucci, CERN

  • 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

    A. Ceccucci, CERN

  • The Next Step: NA48/3 K+ p+ n n at the CERN-SPS SPSC-2004-029SPSC-I229Cambridge, CERN, Dubna, Ferrara, Firenze, Mainz, UC Merced, Perugia, Pisa, Saclay, Sofia, Torino, + ??

    Work inspired by:High Quality NA48/2 charged Kaon beams and Beam SpectrometersOutstanding Progress by BNL E787/E949 In flight technique with separated beam proposed by FNAL CKM not ratified by HEPAP P5

    A. Ceccucci, CERN

  • K+p+ nn : TheoryPrediction (CKM Workshop): BR(K+ p+nn) = 8.0 1.1 10-11Expect improvements NNLO calculation + reduction parametric uncertainty 4 % error (Buras)

    The hadronic matrix element can be extracted from the well measured K+ p0 e+ n No long distance contributionsQCD NLOBuchalla,Buras 1999

    A. Ceccucci, CERN

  • Main K+ decay modes competing with K+p+ nn BR(K+p+ nn)~10-10 !!

    Decaym+np+p0p+p+p-p+p0p0p0m+np0e+nBR63 % 21 % 6 % 2 % 3 % (called K+m3) 5 % (called K+e3)Suppression:m PID, kinematicsg veto, kinematicsCHV, kinematics veto, kinematics veto, m PID veto, E/P

    A. Ceccucci, CERN

  • K+p+ nn : State of the artBR(K+ p+ nn ) = 1.47+1.30-0.89 10-10 Twice the SM, but only based on 3 events

    hep-ex/0403036 PRL93 (2004)Stopped K~0.1 % acceptanceAGS

    A. Ceccucci, CERN

  • NA48/3 (I229): Decay In FlightCollect 80 K+p+ nn events in about two years of data taking for:4 1012 Kaon decays/SPS yearBR( K+p+ nn )~10-10Acceptance ~ 10%

    Absolute advantage: High energy kaon beam: >35 GeV of EM energy deposited in the vetoes Vey Difficult to miss p0 !!

    Disadvantage: Unseparated Kaon beam

    Region IIRegion IP(K)=75 GeV/c

    A. Ceccucci, CERN

  • NA48/3 Detector Layout800 MHz(p/K/p)Only the upstream detectors see the 800 MHz beam10 MHz Kaon decaysK+p+nnundetected

    A. Ceccucci, CERN

  • Acceptance AcceptanceAcceptanceRegion IRegion II75 GeV/c

    A. Ceccucci, CERN

  • New high-intensity K+ beam for NA48/3 AlreadyAvailable

    Beam:Present K12(NA48/2)New HI K+> 2006Factor wrt 2004SPS protons per pulse on T101 x 10123 x 10123.0Duty cycle (s./s.)4.8 / 16.81.0Solid angle (msterad) 0.40 1640Av. K+momentum (GeV/c)6075Total : 1.35Mom. band RMS: (Dp/p in %) 4 1~0.25Area at Gigatracker (cm2) 7.0 20 2.8Total beam per pulse (x 107)per Effective spill length MHz MHz/cm2 (gigatracker) 5.5182.525080040~45 (~27)~45 (~27)~16 (~10)Eff. running time / yr (pulses) 3* x 1053.1 * 1051.0K+ decays per year1.0x10114.0x1012 40

    A. Ceccucci, CERN

  • GIGATRACKERSpecifications: Momentum resolution to ~ 0.5 % Angular resolution ~ 10 mradTime resolution ~ 100 psMinimal material budgetPerform all of the above in 800 MHz hadron beam, 40 MHz / cm^2Hybrid Detector:SPIBES (Fast Si micro-pixels)Momentum measurement Facilitate pattern recognition in subsequent FTPCTime coincidence with CHOD FTPC (NA48/2 KABES technology with FADC r/o)Track direction

    A. Ceccucci, CERN

  • NA48 WC

    A. Ceccucci, CERN

  • Main Tracker w/o beam pipe??We are considering a full straw tracker operated in vacuum

    A. Ceccucci, CERN

  • COMPASS TRACKERStraw diameter 6 and 10 mm, length up to 3.8 m15 chambers were built in JINRStraw tracker oper

Recommended

View more >