Mostly KLOE. LNF, 15 April 2002

Transcription

1 Mostly KLOE Paolo Franzini Università di Roma, La Sapienza LNF, 15 April 2002

2 OUTLINE 1. KLOE s Mission 2. Why a φ factory (a) φ K 0 K 0 K S K L (b) A pure K S beam 3. KLOE 4. Mesons 5. K S Decays 6. Hadronic cross section LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 2

3 KLOE Mission Study of CP-violation: measurement of R(ɛ /ɛ) to an accuracy of K L π 0 π 0 decays are required to reach δr(ɛ /ɛ) stat =10 4 We guessed that this would require some 11 fb 1 Dated 1 April It takes more... LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 3

4 Feb 2000, second NA48 (CERN) result, KLOE has 300 K L π 0 π 0 events 5 NA Feb 2000 ' Woods E731a NA31 88/89 E731 '99 KTeV '99 NA48 '00 NA48 KTeV '01 KLOE ' pb LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 4

5 ' KLOE vs NA48 and KTeV 500 pb = KLOE, scaled from NA48 ' =0.51 / NK ( L 0 0 ) KTeV NA pb = pb = ,000 pb = LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 5

6 e + e φ e p q 4 3 b k 2 1 e p q W (MeV) σ σ 0 =4µb ( e + e φ, s =(1.02) 2 GeV 2) 3 µb K-pair peak is displaced LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 6

7 φ decays Mode BR, % K + K 49.2 K 0 K π + π π ηγ 1.3 π 0 γ 0.1 other <0.1 Maybe... LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 7

8 φ K 0 K 0 i = K0, p K 0, p K 0, p K 0, p 2 K S p K 0 + q K 0 K L p K 0 q K 0 p 2 + q 2 =1 p 2 + q 2 =1 i = K S, p K L, p K L, p K S, p 2(qp + q p) CPT invariance requires p = p and q = q LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 8

9 1. Pure, K L, K S, K 0, K 0 beams 2. Kaon interferometry From unitarity and σ(γγ K 0 K 0,J P =0 + ) e + e K S K S or K L K L e + e φ K S K L few Unique opportunity to study: K S BR s to high accuracy K S Rare decays: K S semileptonic... K S π 0 π 0 π 0, K S π 0 ν ν in addition to CP and CPT, the original mission of KLOE. LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 9

10 DAΦNE Parameter Design 2001 Bunches Current (A) L (µb 1 s 1 ) Background Small Large 1y Ldt (pb 1 ) (?) Crossing angle= mrad LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 10

11 DAΦNE October 10: L pk =40 µb 1 s 1 L=2.1 pb 1 /d Improved τ beam and background Still much too high! LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 11

12 DAΦNE November 25: L pk =51 µb 1 s 1 L=2.2 pb 1 /d Worse τ beam and background Always much too high! Record Nov 26: 2.7 pb 1 /d Best day Dec 7: 3pb 1 /d LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 12

13 KLOE γβcτ L =3.4 m Drives detector size γβcτ S =5.6 mm Drives IP surroundings LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 13

14 KLOE YOKE S.C. COIL Cryostat Barrel EMC DRIFT CHAMBER End Cap EMC Pole Piece 7m 6m LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 14

15 52,000 wires - Al + W. All C-fiber construction. Spherical end-plates tensioned while stringing. He + 10% iso-c 4 H 10 + water 0.5%. Wire tension measured electrostatically. LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 15

16 KLOE Calorimeter Pb-scintillating fibers L 4.5 m Both ends read out 4880 pm tubes σ(e)/e=5.7% at 1 GeV σ(t)=70 ps at 1 GeV σ(x, y)=1.2 cm σ(z)=1.2cmat1gev Provides trigger signals Drift chamber 4 m dia., 3.5 m long 12,000 cells, 2 2, 3 3 cm 2 All stereo, variable σ(d) 120 µm B=6 kg σ(p )/p =0.4 %, θ>45 de/dx, 12-wire groups Provides trigger signals LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 16

17 KLOE Trigger Single energy release in EMC Dual thresholds Combinatorial logic Saturated hit counts in DC layers, fast and slow Slow count can abort trigger Bhabha trigger Cosmic ray veto Luminosity measurements Calibration EMC E: Cosmic rays : γγ EMC t: Cosmic rays : γγ DC s t: Cosmic rays : Bhabha Momentum scale: M K Calibration from data, requires 1 h (100 nb 1 ) LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 17

18 Feedback to DAΦNE, in real time Luminosity Machine energy Beam x-ing position X-ing angle Beam size, except vertical Background counts LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 18

19 The first events, April 99 K L K L K S K S π + π, K L π + π K S π 0 π 0, K L interacts in ECal LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 19

20 φ K S K L K S π + π or K S π 0 π 0 γ Par Val Unit E K 510 MeV p K 110 MeV β K 0.2 γ K 1.04 E γ MeV p π MeV LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 20

21 Kinematics 1 E 2 K = m2 K + p2 K δe K = βδp K 2 E K = m K γ δe K = E K βγ 2 δβ K 3 m 2 K = E2 K ( p π + + p π ) 2 δm K = 2βδpK 1. With one event p(k S π + π ) δw DAΦNE 0.4 MeV 2. With one event β(k L ) δw DAΦNE 0.8 MeV 3. With one event m(k S π + π ) KLOE scale to 0.4% LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 21

22 W MeV From K, K L From K, K L From pk, K S S S S Run No LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 22

23 For events with both K S π + π and K L -crash two independent measurements of W : W S and W L. Take: = W S W L and Σ = W S + W L. The intrinsic machine energy spread cancels in. rms fluctuation of due to KLOE resolution σ E rms(σ)= σe 2 + σ2 W, where σ W is the DAΦNE intrinsic energy spread, 2 σ B with σ B the energy spread of the beams. From rms( ) rms(σ) computed run by run we find σ W. LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 23

24 1.0 rms( W) MeV Intrinsic DA NE energy spread W=1019 MeV, W 0.65 Mev E=510, E 0.4 MeV Run nr LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 24

25 KLOE performance From p K : δe K =(p K /E K )δp K = β K δp K 0.5 Mev δw DAΦNE 0.1% from one K S π + π decay! From M K : Let k 1+ɛ be the momentum scale factor δɛ 0.25% from one K S π + π decay! LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 25

26 KLOE performance A Calorimeter 300 = e K S I K L e D = or t =700 ps Measure K L path by t(i A) and K S direction Tag K S from K L -crash ( K L ) W(DA NE)=1 MeV gives =0.004 LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 26

27 Efficiencies 1. γ efficiency vs E,θ 2. Track efficiency 3. Vertex efficiency 4. Trigger efficiency From K L π + π π 0 π + π γγ find direction and momentum of other γ.compare with cluster finding result. Adjust algorithm efficiency E, MeV All done from data. MC cross checks/adjustments. LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 27

28 Absolute scale calibration 3 b SCAN 300,000 K S events M = MeV 2 δm =10keV Calibrates scale by comparing with g 2 1 measu- depolarization rements W (MeV) Rad corr, β LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 28

29 PHYSICS Because of low L we cannot study CP or very rare processes. We try: 1. Semi rare processes: BR 10 4, 5 2. Precise measurements of poorly known quantities 3. Energy scan without machine energy change Major obstacle is large background, changing across sample. Measurements change by 1-2% through a fill. And there are cancellations. Could use only 2/3 of 2000 data. We hope to be ready to use 01 data and to get cleaner data soon. LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 29

30 On Background Background contaminates events resulting in loss of good signal and inclusion of wrong signal. We must correct for that. Background also increases trigger rate and data volume. Ionly remark on the first point, f s below are frequencies. From: f bad = f evnt T f bckgnd f bad /f evnt f bckgnd. Or, to put it another way, a constant L/B ratio means that the fraction of contaminated events grows with L. L/B should decrease at least as 1/L. The increased L might not be in the end usable. Of course we try our best. LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 30

31 q q spectroscopy Level diagram s s contents Gluon contents Chiral expansion S * * S S S * * * PJ aff,,' 1500 MeV a, f?? 950 MeV J PC 0 1 (0, 1, 2) LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 31

32 Pseudoscalars: η and η ev/bin events M MeV Singlet-octect mixing η = η 8 cos θ η 1 sin θ η = η 8 sin θ + η 1 cos θ Gluon mixing φ ηγ; η π + π π 0 φ π + π 3γ φ η γ; η ηπ + π ; η 2γ φ π + π 3γ Same final state Γ(φ η γ)/γ(φ ηγ)= (5.3 ± 0.5 ± 0.4) 10 3 LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 32

33 The pseudoscalar sector: the η η mixing angle θ P in the flavor basis has been extracted from the ratio of the two BR s. The KLOE measurement is the most accurate to date: θ P =( The absolute value of BR(φ η γ): 1.5 ) KLOE Collaboration, hep-ex/ BR(φ η γ)=(6.8 ± 0.6 stat ± 0.5 syst ) 10 5 KLOE Collaboration, hep-ex/ together with the value of the mixing angle definitively rules out models with large gluonium content of the η meson. LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 33

34 Scalars: f 0 and a 0 events The scalars puzzle Wrong mass What are they q q, gg q qq q, K K... Combination of the above I =0, f 0 π 0 π 0 φ f 0 γ, f 0 4γ φ 5γ e e LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 34

35 Scalars: a 0 ev/25 MeV a a bckgnd tot I =1, a 0 / π 0 π 0 φ a 0 γ, a 0 ηπ 0 φ 5γ M MeV LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 35

36 Signal shape d / dm f 0 f 0 BW 0.2 M GeV dγ/dm ππ BW k 3 Overlap LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 36

37 Fit to the M ππ spectrum M ππ spectrum fitted with a theoretical dn/dm shape (qqqq) foldedwith analysis efficiencies, experimental resolutions and reconstruction effects. No φ ρ o π o π o π o γ contribution considered / KLOE 2000 DATA Resulting f 0 shape M ππ (MeV) M ππ (MeV) Resulting shape used for MC f o simulation KGM, Dic BR Measurement of φ π o π o γ S. Giovannella LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 37

38 φ Scalars. Results BR(φ f 0 γ π 0 π 0 γ)=(1.49 ± 0.07) 10 4, BR(φ σγ π 0 π 0 γ)=(0.28 ± 0.04) 10 4, BR(φ f 0 γ)=(4.47 ± 0.21) 10 4, BR(φ a 0 γ,a 0 ηπ 0 )=(7.4 ± 0.7) 10 4, BR(φ f 0 γ)/br(φ a 0 γ)=6.1±0.6, Iso-spin mixing: θ =30 ± 3 and Ff 2(r)/F a 2 (r) =0.27 Information so far unavailable about the structure of the scalars. LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 38

39 φ π + π π 0 BR(φ ggg π + π π 0 )=15.5% (Origin of OZI-rule) Dominated by ρπ s s 3 s Large sample of ρ +, ρ, ρ 0 ``1'' Precise and consistent measurement of M ±,0,Γ ±,0 Relevant to δa µ, hadr Background limits M accuracy. LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 39

40 φ π + π - π 0 21 φ π + π - π 0 direct 3 contributions to the Dalitz plot E m GeV e + e - ωπ 0 (E + - E )/ 3 GeV CPT test to 5x10-4 preliminary φ ρ ±,0 π 0, ± Mρ + (MeV/c 2 ) Mρ 0 (MeV/c 2 ) M + (MeV/c 2 ) Γ(MeV/c 2 ) A(dir.)/A(ρπ) φ(dir.)-φ(ρπ) Fit free parameters: M ρ, Mρ, Γ ρ & decay amplitude Efficiency from Monte Carlo KLOE Fit (preliminary ) ± ± ± ±1.0 (8.5 ±0.5)% (88 ±9) o PDG ± ±0.8 (-15 11)% - Paolo Valente INFN LNF Hadron 2001 LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 40

41 I =1/2 Chiral expansion parameters Calculation of R(ɛ /ɛ) BR s for K S decays (and K L ) K S -decays R =Γ(K S π + π )/Γ(K S π 0 π 0 ), not well known, few% (L + /L 00)/(S + /S 00) known to 0.1% Would like to reach 0.1% on former. Corrections are background sensitive. LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 41

42 Γ(K S π + π )/Γ(K S π 0 π 0 ) K S decays 1 RF bucket ( K L ) K L interacting in the calorimeter gives an ideal K S tag, almost independent of K S decay mode LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 42

43 Trigger eff >96.5% Overall accept. 57% ALL FROM DATA Systematic errors Source Error, % Tracking 0.2 Cluster count 0.5 Trigger 0.06 Cosmic-r. veto 0.35 Tagging 0.4 Total 0.76 '76 '74* '73 '72 '72 '72 '71* '70 '69 K K S PDG: KLOE: S R = 2.239±0.003(stat.)±0.015(syst.) 2000 data KLOE includes all K S π + π γ, others inc. unknown fraction. LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 43

44 K S semileptonic: K S πeν Γ(K L ) Γ(K S ) CPT Begin with K-crash as a K S -tag Events/1 MeV Data 17 pb DMC fit Use only non spiralling tracks TOF for electron ID Compare E miss with p miss Almost complete rejection of π + π background 630 events E p MeV M M Events CMD-2 DE, MeV LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 44

45 K S πeν We ask for two tracks reaching calorimeter, low eff! Overall efficiency: 21.8% 627 ± 30 signal events KLOE : Γ S,l3 =Γ L,l3 : BR(K S πeν) =(6.79 ± 0.33 ± 0.20) 10 4 BR(K S πeν) =(6.7 ± 0.07) 10 4 Pure sample An order of magnitude increase in no. of events wrt Novosibirsk Could reach present K L accuracy with 200 pb 1 Background sensitive LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 45

46 K S πeν Most interesting are the leptonic asymmetries A l S,L : A l N + N N + + N =2R(ɛ + x + δ + y + x ) ɛ C\P\ in mixing x S = Q δ C\P\T\ in mixing y direct C\P\T\, S = Q x direct C\P\T\, S = Q Some terms cancel in A l S Al L : measure δ Signs are symbolic, some change under K S K L. LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 46

47 Charged Kaons Together with K L -decays measure sin θ C to a fraction of 1%. Many of the other channels remain poorly known. Also remeasure all BRs for φ all channels Measure σ(e + e φ) Then comes C and CP! LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 47

48 e + e hadrons Why... a µ, theory a µ, exp =(260 ± 160) 10 11, (discrepancy was 430 but... found a mistake) with 160 = 140 Ex 67 Th Should we get excited? δa µ, EW = preposterous... in view of LEP, M(top), b sγ, R(ɛ /ɛ), sin 2β But think, if it were true... LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 48

49 u, d, s... g δa µ, had , is not computed: s p-qcd Measure σ(e + e hadrons) and use dispersion relations: Low mass π + π (ρ, ω) contributes δa µ =5000±60, from e + e ρ, ω π + π at Novosibirsk and from τ hadronic decays. (Requires I-spin breaking, M(ρ ± )-M(ρ 0 ), I=0 cntrib... corrections) LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 49

50 and 60 < 140. But 60 > 50, final BNL error... Important to check it. Radiative return 1. Scan: change collider energy: 2m π <W <W max or 2. At fix energy W, select e + e γπ + π,2m π <M ππ <W e e hard Problems with ISR and FSR, complicated calculations, radiative corrections need understanding, good normalization. At low mass, dimuon production exceeds dipion. ISR and vacuum polarization cancel LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 50

51 1000 Contribution 11 to ( x10 ) a , nb F,au W (MeV) LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 51

52 A direct measurement of R(had) R = σ(e+ e hadrons) σ(e + e µ + µ ) = σ(e+ e hadronsγ) σ(e + e µ + µ γ) 1. Possible if σ(µ + µ )>σ(π + π ). No need for independent L measurements (Bhabha). 2. Initial state radiation and vacuum polarization corrections cancel. 3. OK for M(ππ) < 600 MeV, δa µ LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 52

53 1.4 b Amendolia et al s, GeV LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 53

54 KLOE, preliminary Ldt = 22.6 pb 1 d (e e )/dm (nb/gev) Black = MC Red = data M (GeV) LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 54

55 KLOE, preliminary d (e e )/dm (nb/gev) Ldt = 22.6 pb 1 M (GeV) LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 55

56 200 pb 1 should allow measuring the contribution to a µ to ± out of It is important to get a good measurement using an independent method. LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 56

57 Conclusions DAΦNE is beginning to show promise. KLOE has begun its program. Major DAΦNE upgrades in LNF, 15 April 2002 Paolo Franzini - Mostly KLOE 57