Status of KLOE and DAFNE

Transcription

1 EtaMesonNet Meeting 14/10/2004 Status of KLOE and DAFNE Cesare Bini (Universita La Sapienza and INFN Roma) For the KLOE collaboration 1. Overview of physics at a φ - factory 2. The collider DAFNE 3. The KLOE experiment 4. Overview of KLOE results Vus from K L decays Hadronic corrections to g-2 5. Conclusions and Outlook

2 1. Overview of Physics at a φ - factory DAFNE: e + e - collider at center of mass energy W=1020 MeV at Laboratori Nazionali di Frascati INFN W=1020 MeV φ meson peak σ(e + e - φ all) ~ 3 µb W scan around the φ peak ( φ K S K L )

3 Why at the φ peak? Because it is a source of interesting physics BRs of φ decay channels (from PDG) 1) Kaon pairs: K + K = 49.1% K 0 K 0 = 34.0% 2) 3 pions π + π π 0 = 15.4% (including ρπ) 3) Radiative decays ηγ = 1.3% π 0 γ = η γ = ππγ = ~10-4 (including f 0 (980) γ) ηπ 0 γ = ~10-4 (including a 0 (980) γ) 4) Conversion decays ηe + e - = π 0 e + e - =

4 Kaon physics: monochromatic ( p = 110 MeV/c ) kaons (charged and neutrals); coherent production mutual tagging Neutral kaons are produced in a pure quantum J PC = 1 state: λ S = 6 mm λ L = 3.5 m i = = N 2 [ K ( p) K ( p) K ( p) K ( p) ] r r r r [ K ( p) K ( p) K ( p) K ( p) ] S r L Pure K S and K L beams K S, K L physics Kaon interferometry High statistics of K ± ; K ± decays and asymmetries 3 pions φ ρπ samples of ρ +, ρ - and ρ 0 CPT and Isospin tests Study of direct φ π + π π 0 coupling r L r S r

5 Radiative decays (1): Since φ = <ss> state (almost pure) φ Mγ is related to the s-content of M Nature of scalar mesons ( f 0 (980), a 0 (980), σ ) Pseudoscalar mixing angle ( comparison of φ ηγ and φ η γ ) Radiative decays (2): Source of monochromatic pseudoscalar mesons; φ ηγ : E=363 MeV photon + η decay σ = 30 nb φ π 0 γ : E=501 MeV photon + π 0 decay σ = 3 nb φ η γ : E= 60 MeV photon + η decay σ = 0.2 nb η and η physics

6 Radiative Return: W=1020 MeV σ(e + e - hadrons) 2M π < Q < W Q dσ ( e e π π γ ) = σ ( e e π π ) H ( Q ) 2 dq H(Q 2 ) is the radiator function fully provided by Montecarlo based on QED (Eva, Phokhara, big effort from theoreticians) σ(e + e - hadrons) [2M π < Q < M φ ] 67% of error on a µ (hadr) Fundamental ingredient for precision test of the Standard Model

7 2. The collider DAΦNE 2 separate beams 2 interaction regions (cannot run simultaneously) 120 bunches / beam Bunch I.R.: ~ 20 µm 2 mm 1 cm Bunch spacing = 2.7 ns Continuous alternate injection (topping up) every mins Project luminosity = cm -2 s m

8 DAΦNE history : Spring 1999 First collisions: KLOE test run 2000 KLOE Run L int = 20 pb KLOE Run L int = 200 pb KLOE Run L int = 250 pb DEAR Run L int = 110 pb FINUDA Run L int = 250 pb KLOE Run L int = 420 pb -1 (up to date) Luminosity progress

9 1 standard day of DAFNE/KLOE operation (4/10/2004) Blue = e - curr. Red = e + curr. Instantaneous Luminosity Integrated Luminosity ( 6 pb -1 /day ) L = cm -2 s -1 ~ 300 φ /s η / day, 1500 η / day

10 3. The KLOE experiment

11 The KLOE detector Pb-SciFi Calorimeter ( barrel + endcap, 15 X 0 depth, 98% solid angle coverage) Iron Yoke SC Coil kg 0.52 Τ magnetic field Large volume Drift Chamber (13K cells, He gas mixt.) Interaction region: Instrument quadrupoles, Al-Be spherical beam pipe

12 The KLOE Calorimeter Pb-Sci.Fi. Structure Light guides + PMT read-out Energy, Time and impact position measurements. Lead 1.2 mm 1.0 mm 1.35 mm σ ( E ) = E 5.7% E( GeV ) 54 ps σ ( t) = 140 ps E( GeV )

13 The KLOE Drift Chamber Light mechanical structure (carbon fiber) < 0.1 X 0 Gas Mixture = 90% He 10% Isobut. / All stereo wires z Hit position measured with σ( r ) ~ 200 µm and σ( z ) ~ 2 mm p(mev/c) resolution for 510 MeV/c electrons and positrons σ(p)/p ~ % M(MeV/c 2 ) resolution for Ks π + π - σ(m) ~ 1 MeV/c 2 Polar angle M(π + π - ) (MeV/c 2 )

14 Time (2002 d.t.) KLOE Data Taking 1.Continuous data taking: no stop at beam injection; 2.Trigger: 2 energy clusters above threshold ( MeV) OR > NNN hits in the drift chamber Trigger Rate (khz) = 1 (physics) (Cosmic rays) (Bckg) = 2.3 khz 3.On-line calorimeter calibration: (every 200 nb -1 ~ 1 h) Energy (absolute scale from e + e - γγ) Time (absolute scale using DAFNE RF signal (2.715 ns)) Rel. energy Variations (%) Endcaps Barrel

15 4.Drift Chamber t 0 s and space-to-time relations calibration: Iterative procedure based on cosmic ray runs; On-line check of residuals using Bhabha and cosmic rays s-t relations residuals vs drift distance On-line check of residuals with selected Bhabha events

16 5. Data quality control On-line reconstruction evaluation of relevant quantities run by run: These variables are used in the data reconstruction procedure and to provide information to the DAFNE team. W (MeV) p φ (MeV) W= s center of mass energy p φ φ momentum (lab. boost) x V, y V, z V interaction point coordinates x V (cm) z V (cm) Run Number

17 6. Data reconstruction: End of run: if (calibration_ok) start Data reconstruction Calorimeter clusters Tracking in Drift Chamber Background rejection (cosmic rays, machine bkg.) Event classification Big computing effort; ~ 120 CPU used ~ 300 TB tapes (including raw data, DST files and MC events)

18 (1) Kaon physics K S πeν 4. Overview of KLOE results Phys. Lett. B (2002) Preliminary update presented at ICHEP 04 K S π + π (γ) Phys. Lett. B (2002) K S π 0 π 0 Update with data in progress K L γγ/k L 3π 0 Phys. Lett. B (2003) K + π + π 0 π 0 Phys. Lett. B597 2 (2004) K 0 mass Upper limit BR(K S π 0 π 0 π 0 ) KLOE Note 181 ( Paper in preparation K L πµν,πeν,π + π - π 0,3π 0 Preliminary results presented at ICHEP 04 V us from K L and K S Preliminary results presented at ICHEP 04 K L mean life Preliminary results presented at ICHEP 04 CP violation & interference V us from K ± In progress In progress

19 (2) Other results (radiative decays ) φ π 0 π 0 γ φ ηπ 0 γ φ η γ, ηγ (mixing angle) Phys. Lett. B (2002) Updates in progress Upper limit BR(η 3γ) Phys. Lett. B (2004) Hadronic cross section (0.35 < s < 0.95 GeV 2 ) Upper limit BR(η π + π - ) φ leptonic width Phys. Lett. B (2002) Updates in progress Phys. Lett. B (2002) Updates in progress φ ρπ, π + π - π 0 Phys. Lett. B (2003) Paper submitted to Phys. Lett. B Paper in preparation Paper in preparation Dalitz plot η 3π Preliminary results presented at ICHEP 04 BR(η π 0 γγ) Preliminary results presented at ICHEP 04 Search for f 0 (980) π + π Preliminary results presented at ICHEP 04 Hadronic cross section (down to 2M π2 =0.08 GeV 2 ) In progress

20 KLOE contributions to 2 frontier problems in high energy physics: (1) Unitarity of the CKM matrix through V us precision measurement (2) Hadronic corrections to the muon anomaly a µ (1) Unitarity Test: V us At present the most precise test of unitarity of CKM matrix comes from 1 st row: V ud 2 + V us 2 + V ub 2 ~ V ud 2 + V us 2 1 = ± ( PDG02 ) V ud is extracted from nuclear β decay (Czarnecki-Marciano-Sirlin hep-ph/ ) V us is extracted from partial widths of kaon semileptonic decays Γ(K πlν(γ)); Γ(K πlν(γ)) V us f + Kπ (0) 2 S ew I i (λ +,λ 0,0)) (1 + δ i em + I i /2) f Kπ + (0) form factor at 0 momentum transfer: pure theory calculation (χpt, lattice) I(λ +, λ 0,0) phase space integral, S ew short distance corrections (1.0232) λ +,λ 0 δ ι em+ I i /2 slopes (momentum dependence of the vector and scalar form factors) long distance radiative corrections for form factor and phase space

21 KLOE measures all kaon semileptonics decays with tagged kaon beams K S π ± eν, π ± µν K L π ± eν, π ± µν K ± π 0 eν, π 0 µν K L semileptonic decays (preliminary results ICHEP 04) N 0 tagged K L λ L = 3.4 m δn i i=1,4 (4 main K L decays in δt) ε i = efficiency to detect channel i Prob(δT,τ) = prob. to decay in δt BR i = δn i / ( N 0 ε i Prob(δT,τ) ) (1) τ from fit of time distribution (2) Impose Σ i BR i = 1 - ε further equation determination of τ and single BR i

22 Results: BR(K L πeν) = ± ± BR(K L πµν) = ± ± BR(K L 3π 0 ) = ± ± BR(K L π + π π 0 ) = ± ± τ = (51.15 ± 0.20 ± 0.40) ns (meth.(1)) τ= (51.35 ± 0.05 ± 0.26) ns (meth.(2)) Consistency check of the method K L πeν sample K L πµν sample P miss E miss in πe or eπ hyp. (MeV) P miss E miss in πµ or µπ hyp. (MeV)

23 1. K 0 l3 partial decay widths measured by KLOE Γ(e3,µ3)= BR(e3,µ3) / τ 2. f + Kπ (0) from Leutwyler-Roos 0.961(8) confirmed by Becirevic et al. (lattice+chpt) 0.961(9) 3. quadratic parametrization of form factors (+ slopes from ktev measurements) V us = ± (exp.) ± (the.) preliminary Comparison with Unitarity: V us f +K (0) New results indicate no deviations from CKM unitarity

24 (2) Hadronic corrections to g-2 Precision test of the Standard Model: a µ exp vs. a µ th = a µ QED + a µ weak + a µ had a µ QED = ( ± 0.28) a µ weak = ( 15.4 ± 0.2 ) A µ had = ( 693 ± 7 ) a µ had,lo = Im[ ] hadrons 2 a had, lo µ 1 4π = 3 2 π 4m σ e + e hadr ( s) K( s) ds K(s) ~ 1/s (kernel function) The e + e - π + π - channel accounts for ~72% of the contribution both to a had µ and to σ 2 (a had µ )

25 Radiative Return Method: select π + π γ events with θ γ < 15 o Enhancement of ISR vs. FSR Effective threshold in S π events / 141 pb -1 number of events (x10 3 ) H(Q 2 ) s π (GeV 2 ) Our cuts select events with s π >550 MeV Integral a µ had

26 KLOE (375.6 ± 0.8 stat ± 4.8 syst+theo ) CMD-2 (378.6 ± 2.7 stat ± 2.3 syst+theo ) % Error 0.9% Error KLOE (hep-ex/ ) Submitted to Phys. Lett. B EJ95 (e + e - ) 186.8±15.7 DH98 (e + e - +τ+qcd) 176.8±7.2 DEHZ02 (e + e - based) 169.3±7.8 HMNT02 (e + e - based) 166.9±7.4 DEHZ03 (e + e - based) 180.9±8.0 DEHZ03 (τ based) 195.6±6.8 BNL-E µ + 203±8 BNL-E µ - 214±8.5 BNL-E ave. 208±6 BNL-E a µ (10-10 ) KLOE confirms a deviation of 2.7σ (according to an updated analysis of DHEZ) btw. theory and experiment for (g-2) µ!

27 KLOE data are relevant because they confirm e + e - - τ data discrepancy g µ -2: e + e - Data vs τ Data KLOE agrees with CMD-2: τ data disagrees with e + e -

28 5. Conclusions and outlook KLOE 4 th period of data taking. Several results reached: among the latest V us determination hadronic corrections to g-2 DAFNE program: KLOE run until L(int) = 2 fb -1 with present luminosity it means ~ 10 months data taking (realistic estimate) φ decays η decays η decays