risultati recenti dell’esperimento kloe alla f -factory da f ne - frascati

A. Passeri Risultati recenti di KLOE 1

Risultati recenti dell’esperimento KLOEalla -factory DANE - Frascati

Antonio PasseriINFN Sezione Roma [email protected]

A nome della collaborazione KLOE

XCI Congresso Nazionale della Società Italiana di FisicaCatania, 26 settembre 2005

mailto:[email protected]


The DANE -factory

• Ebeam 510 MeV

• 2 separate rings for e+ and e- to minimize beam-beam• high current (20 mA per bunch)• up to 120 bunches•Crossing at 12.5 mrad angle

• Ebeam 510 MeV

• 2 separate rings for e+ and e- to minimize beam-beam• high current (20 mA per bunch)• up to 120 bunches•Crossing at 12.5 mrad angle


Luminosity (pb-1)

2001-02 440

2004 680

2005 (up to 15 Sep)

710

Total 1830

KLOE data sample

Excellent running at beginning of september: peak luminosity: 1.4 1032

integrated lum: 90 pb-1 in 15 days

Only 2001-02 sampleAnalyzed so far.

Plan to run up to end 2005 on peak (expect 2 fb-1 for 2004-05 data overall)An off peak run planned in 2006


E/E5.7% / E(GeV)

T 54 ps / E(GeV) 50 ps

• PID capabilities mostly from TOF

L() ~ 1.5 cm (p0 from KL )

B = 0.52 T4m-, 3.75m-length, all-stereop/p = 0.4 % (tracks with > 45°)

xhit 150 m (xy), 2 mm (z)

xvertex ~1 mm

KLOE detector performancesKLOE detector performances


(1020)

a0(980)

f0(980)

'

KK

0-

0- 1-

1-

0+

0+

BR 15%

BR 83%

BR 1.3%

KLOE PhysicsKLOE Physics

Main focus on KAON physics• CP double ratio/interferometry• CPT test with semileptonic Ks , KL charge asymmetries

• Vus , kaon form factors from

semileptonic KS,L ,K decays• Rare KS,L decays ( KS 30, , KL ...)

Non Kaon Physics• radiative decays (scalars, pseudoscalars + photon)• final states• hadronic cross section


KLOE has the unique capability of selecting pure KS and KL beams

Decays

K+K– 49.1%KLKS 34.3% 15.4% 1.3%

Advantages of -factory environment

The presence of one kaon tags the other one on the opposite side

All KS decay near the i.p.

• The final KK state has the samequantum numbers as the i.e. is a pure JPC = 1- - quantum state

• PK=-PK ~110 MeV/c

• (KS) = 6 mmps), KLm ns)

pppp ,,,,2

1SLSL KKKKi


KLOE preliminary380 pb1 ’01 + ’02 data

Fit with PDG values for S, L:

m = (5.34 0.34) × 10 ħ s1

PDG ’04: (5.301 0.016) × 10 ħ s1

Fix m to PDG ’04 value, obtain:

No simultaneous events:same final state/ antisymmetric initial state

Peak position sensitive to m

Coherent KL regeneration on beam pipe

|t1 t2|/S

S,L = 0.0430.0380.035 0.008

S,L = 0.130.160.15

cf. Bertlmann ’99 (CPLEAR):

• Data: 7366 evts– Fit: 2/dof = 15.1/22

I(t) eLt eSt 2(1 S,L) eS Lt2 cos(mt)

KL(S) at t2KS(L) at t1

Kaon interferometry and QM coherence


•Clean KS tag by time of flight identification of KL interactions in the calorimeter (Kcrash)• KL velocity in rest frame = 0.218• crash 30% (mostly geometrical)• provides a good estimate of KS direction in and momentum 1MeV

• KL tag by requiring two oppositecharge tracks from IP• Loose cuts on pKs and MKs

• tag ~ 70% (mainly geometrical)• Good determination of KL direction

(1) and momentum (1MeV)

KS and KL “beams”

KKSS

KKLL 2 2

KKLL “crash”“crash”= 0.22 (TOF)= 0.22 (TOF)

KKSS ee


Charged kaons Tagging

Measurement of absolute BR’s: K beam tagged from K

p*(MeV)

Kinem. ID

180 200 220 240

1000

3000

2000

102 Ev/0.5MeV

Data

— fit:

K++ K––0

–

–

++

• Two-body decays identified as peaks in the momentum spectrum of secondary

tracks in the kaon rest frame: 6•105 tags/pb-1


KS Phys. Lett. B538 21 (2002)KS NEW Update with ’01-’02 data sample

KSePhys. Lett. B535 37 (2002) Updated with ’01-’02 data sample

KS Phys. Lett. B 619 61 (2005)KS +-0 In progressK0 mass KLOE Note 181 (http://www.lnf.infn.it/kloe)KL KL 30 Phys. Lett. B566 61 (2003)

KL, e, +-0, 30 NEW Accepted by Phys. Lett. B

KL lifetime NEW Accepted by Phys. Lett. B Semileptonic form factors NEW Preliminary results available

CP violation & interference NEW Preliminary results available

Vus from K+/- Paper in preparation

Vus from K+/- lNEWPreliminary results available

K+/- lifetime In progress

K+ +00 Phys. Lett. B597 139 (2004)

KLOE results in kaon physics


from 1st row:

Can test if = 0 at few 10-3:from super-allowed 0+ 0+ Fermi transitions, n -decays: 2|Vud|Vud = 0.0010from semileptonic kaon decays (PDG 2002 fit):

|Vud|2 + |Vus|2 + |Vub|2 ~ |Vud|2 + |Vus|2 1 –

• Extract |Vus| from Kl3 decays. EM effects must be included:

(K ℓ) I(t) (1 + I(t,)) (1 + ) SU(2)|Vus f+K0-(0) |2

|Vus| t) f+K0-(0)= 0.5 _ 0.05

|Vus| t) f+K0-(0)

2|Vus|Vus = 0.0011

Relative uncertainty:

• Extract |Vus| from (K())/(()) ratio. Dominated by the theoretical

uncertainity on the fK/f evaluation.

KLOE can measure all experimental inputs: BRs, lifetimes, and form factors !

KLOE is performing a precise measurement of |Vus|

i.e. the most precise test of CKM matrix unitarity

KLOE is performing a precise measurement of |Vus|

i.e. the most precise test of CKM matrix unitarity

Two techniques:


328 pb1 ’01 + ’02 data13 106 KL’s for counting (75%) 25% used to evaluate efficiencies

BR’s to e, , and 0: • KL vertex reconstructed in DC

• PID using decay kinematics• Fit with MC spectra including

radiative processes and optimized EmC response to //KL

BR to 000:• Photon vertex reconstructed by

TOF using EmC ( 3 clusters)• rec = 99%, background < 1%

Lesser of pmiss Emiss in or hyp. (MeV)

e

Data7% of sample

using KL beam tagged by KS

KL branching ratios


L

= (50.72 0.17 0.33) ns

Errors on absolute BR’s dominated by error on L

L needed for geometrical efficiency (FV)

Alternately, set x BR(KL x) = 1 and solve for L

BR(e 0 + 30) from KLOE BR( 00 ) from PDG ’04

= 1.0104 0.0076

FV

L/cBR(K

L e()) 0.4007 0.0006 0.0014 800k evts

BR(KL

()) 0.2698 0.0006 0.0014 500k evts

BR(KL

30) 0.1997 0.0005 0.0019 700k evts

BR(KL

0()) 0.1263 0.0005 0.0011 200k evts

Obtain:

KLOE results for KL BRsKLOE results for KL BRs


Measure using KL 000

• Require 3 ’s• (LK) ~ 99%, uniform in L

• Background ~ 1.3%• L() ~ 2 cm

Use KL 0 to determine:

• EmC time scale• Photon-vertex efficiency

KLOE 400 pb1 ’01 + ’02 data10M KL evts

L = 50.92 0.17 0.25 ns

Average with result from KL BR’s:

L = 50.84 0.23 ns

L/c (ns)

6 – 24.8 ns40 – 165 cm

0.37 L

× 102

cf. Vosburgh, ’72: L = 51.54 ± 0.44 ns

Eve

nts/

0.3

ns

pK = 110 MeVgood lever arm for lifetime measurement

Measurement of KL lifetime


KS semileptonic decay : not only Vus !KS semileptonic decay : not only Vus !

Sensitivity to CPT violating effects through charge asymmetry:

(KS,L -e+) (KS,L +e-)

(KS,L -e+) (KS,L +e-)

_

_AS,L =

AS AL 0 implies CPT

AS = 2(Re K Re K Re b/a Re d*/a)

AL = 2(Re K Re K Re b/a Re d*/a)CPT indecay

CPT inmixing

CP S Q and CPT

(KS l) provides also a test of S = Q rule:

S(l)/L(l) = 1 + 4 Re(x)

Never measured before !


t texp(e) (ns)e

e

t

tex

p(e )

(ns

)Event selection:• KS tagged by KL crash

• Two tracks from IP to EmC• Kinematic cuts to reject

background from KS • Associate tracks to clusters

e/ ID from TOFIdentifies charge of final state

Obtain number of signal events from a constrained likelihood fit of multiple data distributions

Normalize using KS events in same data set

e

e

KSπ e selection


Fit distributions of 5 variables in data with various MC sources

Close kinematics: Emiss(e) pmiss = 0MC includes e and processes

PCA (cm)04 4 880

100

200

300

400

500

Evt

s/0.

2cm

PCA2PCA1

PCA = PCA1 – PCA2 eliminates kinks and badly reconstructed tracks

Data MC fit e bad bad

other

50 5000

100

200

300

400

500

600

700

Emiss(e) pmiss (MeV)100150

Evt

s/M

eVKS e event counting


BR(KLe3)

0.40

0.39

KTeV ’04

KLOE ’05

PDG ’04

KLOE KS assuming S = Q

AS = (2 9 5) 103

Branching ratios:410 pb1 ’01 + ’02 data

cf. BR(e) [KLOE ’02, 17 pb1]: (6.91 0.34 0.15) 104

dominated by statistics: with 2.5 fb1:

AS 3 103 2 Re

Charge asymmetry:

Test of S = Q rule:

(KS) = 89.62 0.05 psAvg. KTeV ’03, NA48 ’02

(KL) = 50.84 0.23 nsKLOE ’05 (avg.)

BR(e) = (3.54 0.06 0.04) 104

BR(e) = (3.55 0.05 0.02) 104

BR(e) = (7.09 0.08 0.05) 104

KS e Results

AL = (3.322 0.058 0.047) 103 [KTeV 2002]

AL = (3.317 0.070 0.072) 103 [NA48 2003]


Cuts on E*() + PCA + vtx

Emiss() pmiss (MeV)

4040 0 2020

• 2002 data MC MC MC

4040 0 2020

Evt

s/M

eV

More difficult: poor charge ID (m m), background from KS ,

3% stat error from fit

Preselection cuts only:Kinematics and TOF

Evt

s/M

eV

Emiss() pmiss (MeV)

First observation of KS First observation of KS


• 1-prong kaon decay vertex in the fiducial volume: VTX in (40,150) cm

• daughter track extrapol. to EMC• Reject two-body decays: p(m) 195 MeV• 0 search: 2 neutral clusters in EmC, with

ToF matching the K decay vertex (t)<3t)

• Spectrum of charged daughter mass, m2

lept, from TOF measurement:

tdecayK = tlept -Llept /(leptc) = t-L/c

K00

K0

K nucl.int.

• Additional kinematical cuts to reject non-semileptonic decays. • The residual background is about 1.5% of the selected Kl3 sample, and has the m

2 signature.

Ev/(14MeV)2

MC

K± semileptonic decaysEvents tagged either by K+2 , K-2, K+2 or K-2 on the opposite side


Tag K+2 K+2 K-2 K-2

NKe3 62 781(321) 24 914(208) 66 657(334) 24 225(204)

NK3 37 461(264) 14 827(170) 39 988(277) 14 608(168)

• Fit m2lept spectrum with a linear combination of Ke3

and K3 shapes, and background contribution.

• Correct MC shapes for Data/MC differences on the calorimeter timing.

• The residual distribution show the same trend for all the tag samples. Possible residual different Data-MC resolution.

Ev/(14MeV)2

• Selected signal events in 2001/2002 data set

K± l signal extraction


• The error accounts for the data and Monte Carlo statistics used in the fit, the MC statistics for the efficiency estimation, the Data/MC efficiency corrections, and the systematics on the tag selection. • The systematics due to the signal selection efficiency is under evaluation.• 2/nDof for the 4 measurements:

Ke3: 3.20/3, P(2> 2) 36%

K3: 5.32/3, P(2> 2) 15%

• taking correlations into account we get:

BR(Ke3) 5.047 0.046 Sys %

BR(K3) 3.310 0.040 Sys %

Tag K-2Tag K+2 Tag K-2Tag K+2

Tag K-2Tag K+2 Tag K-2Tag K+2

KLOE preli

min

ary

• The error is dominated by the error on Data/MC efficiency correction.• Fractional accuracy of 0.9% for Ke3, 1.2% for K3.

K± l preliminary results


KL lifetime from KLOE

L = (50.84 ns

Avg. of direct, BR = 1 determinations

Quadratic form-factor parameterizations:

BR’s from KLOE BR(K

Le) = 0.4007 0.0015

BR(KL) = 0.2698 0.0015

With BR = 1 constraintBR(K

Se) = (7.09 0.09) 104

BR(Ke) = (5.047 0.043)%

BR(K) = (3.310 0.048)%

Expect from unitarityVus f+(0) = 0.2181 0.0022

Vud = 0.9739 0.0003Marciano, CKM ‘05Hardy & Towner ‘04 (SFT)

f+(0) = 0.961 0.008Leutwyler & Roos

pre

lim

.

KTeVISTRA+

KLOE measurements of VusKLOE measurements of Vus


Thanks to F. Mescia (see hep-ph/0411097)

New Vud

= 12.384 0.024 ns [PDG ’04]L = 50.84 0.23 ns [KLOE]

KLOE Vus and rest of the world


• Tag from K--; to reduce the tag bias, tag selection requires EMC trigger.• 2002 data set: 1/3 used for signal selection, 2/3 used as efficiency sample• Count events in (225,400) MeV p* window after the subtraction of 0 identified background. • Selection efficiency measured on data.• Radiated acceptance measured on MC.

BR(K+ +()) = 0.6366 0.0009stat. 0.0015syst.

Following Marciano hep-ph/0406324 :• (K())/(()) |Vus|2/|Vud|2fK

2/f2

• From lattice calculations: fK /f =1.210±0.014

(MILC Coll. hep-lat/0407028)• Vud=0.9740±0.0005 (superallowed -decays)

Vus = 0.2223±0.0025 KLOE preliminary

e

P*(MeV)

Particle momentum in

K rest frame

Nev

/MeV

MC

Vus from BR(K++())


Preliminary KLOE results for KL edecays:

• 328 pb1 of ’01 + ’02 data

• KL decays tagged by KS satisfying trigger ( 30%)

• Two tracks in fiducial volume forming vertex

• Kinematic cuts + TOF PID to reduce background

• Separate mmts for each charge state (e, e) to check systematics

Ke3 phase space phase space

+ FF

Form-factor slopes for K l decays needed for extraction of Vus (evaluation of phase-space integrals)

Parameterization:

t = (pK p)2/m2

For Ke3: f(t) = f(0) [1 t] or

f(0) [1 t½ t2]

Ed B

lucher

t

dN/d

t

KLe3 form-factor slopes


KLOE preliminary 328 pb1 ’01 + ’02 data, 2 106 Ke3 decaysLinear fit:

103 2/dof

e 28.7 0.7 156/181e 28.5 0.6 174/181All 28.6 0.5 330/363

= (28.6 0.5 0.8) 103

Quadratic fit: 103 103 2/dof

e 24.6 2.1 1.9 1.0 152/180e 26.4 2.1 1.0 1.0 173/180All 25.5 1.5 1.4 0.7 325/362

= (25.5 1.5 1.9) 103

= (1.4 0.7 0.7) 103

(, ) = 0.95 103

1

03

KTeV

ISTRA+

KLOE NA48

1 contours

KLe3 form-factor slopes


KS 30 is purely CP violating

If CPT conserved, S = L |000|2

BR(KS 30) = 1.9 × 109

Best previous result from direct search:

BR < 1.4 × 105 90% CL [SND ’99]

Signature (presel ~ 14%):

KL crash + 6 ’s, no tracks from IP

Background rejection:

KS 00 + 2split/accidental clusters

Define signal box in 23 vs. 2

2 plane:

3 cluster pairs with best 0 mass estimates

2 best cluster pairs - 0 masses, E(KS), p(KS), angle between 0’s

22

23

• MC 3 (BR 105)• MC 2

Rare decays @KLOE: search for KS 000


Nbkg(MC) = 3.13 0.82 0.37

Nobs = 2

KLOE 450 pb1 ’01+’02 data

BR 1.2 × 107 90% CL

cf. NA48 ’05 (interference)BR 7.4 × 107 90% CL

Prospects for 2 fb1:

• 6.5 increase in statistics(L efficiency)

• 1.5 decrease in background

Potential to reduce limit ~10

2 2

23

2 2

23

MCEff. Stat. =5.3 data

450 pb1

’01+’02 data

KS 000: Results and prospects


Decay mainly CP-conserving (I = 3/2)BR useful to constrain K 3 amplitudes PDG ’04: BR = (3.21.2

1.0) 107

Based on interference measurements [CPLEAR, E621] New NA48 preliminary

Never observed directly

First use of ’04 data: 740 pb1 total!

Preselection criteria ( = 7%)• KL crash + vertex + 2 clusters

Kinematic fit rejects > 99% of bkg• 6 constraints + m(0) + m(KS)

Remaining backgrounds:• KK Cut on momentum of secondaries at ends of

tracks• KS0

D0(D) Associate tracks to clusters, get e/ ID from

TOF• Both types Veto on extraneous prompt clusters

2 from kinematic fit:

MC background

MC signal (L × ~100)

Search for KS 0


Preliminary results with 740 pb1 ’01 + ’02 + ’04 data:

• Signal efficiency: ~ 1.5% (including KL-crash eff)

• Candidates: 6 events

• Background (sidebands): ~ 3.5 events

• Number of events observed consistent with expectation

• Statistical error: ~ 100%

• Evaluation of systematic error in progress

Scaling these values to 2 fb1 we expect:

• Measurement of BR(KS 0) with 60% error

About the same precision as interference-based measurements

• First measurement of BR from a direct search

KS 0: Current status


KLOE results in “non-kaon” physics

• (ee →hadrons) Phys. Lett. B606, 12 (2005) (small angle Large photon angle analysis in progress

Phys. Lett. B561 55 (2003) f0,a0 Phys. Lett. B536 209 (2002), B537 21 (2002)

update with 2001/02 statistics almost final f0π+π- channel studied ( at large angles)

Phys. Lett. B591 49 (2004)

π+π- New limit available

→preliminaryDalitz plot analysis

preliminary result available

´ Phys. Lett. B541 45 (2002) update with 2001/02 data in progress

continuum:

decays:


• e+e- f0(980) ; f0(980) (I=0) 00 +- +- final state 5 final state e+e- a0(980) ; a0(980) (I=1) 0 +-0 +- + 5 final state • not easily interpreted as mesons (3P0 nonet)• other interpretations: states (Jaffe ’77) molecules (Weinstein-Isgur ’90)• Fit the mass spectra or the Dalitz plot to extract the relevant parameters (masses, couplings, ...): two models exploited

1) “No Structure” – S as simple BW 2) Kaon Loop [Isidori-Maiani, private communication] [Achasov-Ivanchenko, NPB315 (1989) 465]

qq qqqq

KK

S

gKK

gSKK

gSP1P2

P1

P2

K+

K-

S

gS

gSP1P2

P1

P2e+

e-

e+

e-

Light scalar mesons


• f0 Already observed in 00 final state• e+e-+- events with the photon at large angle (45<<135)• Main contributions: ISR (radiative return to , pion FF ), FSR• Look for deviations on Mππ spectrum from the expected ISR+FSR behaviour• Data sample: 350 pb-1 at peak , 676000 events selected•Kaon loop model fits better F-B asymmetry

M() (MeV)

Events/1.2 MeV

f0(980) region

M() (MeV)

f0(980)+-

600 800 M() (MeV)

Asy

mm

etry


P and CP violating decayStandard Model prediction BR ~ 10-27 10-24

=16.6%

BR < 1.3 10-5 @90% C.L.

Normalization to ->3

A by product analysis: - upper limit


E (MeV)

Monochromatic recoil photon very powerful for event id !

produced through M1 transition →P

Erecoil() = 363 MeV very clean sample

Erecoil() = 60 MeV recoil misid. for some channels…

and ’ at KLOE


M6 (MeV)

inv.mass of +-+ 6 out of 7

N = 3405 61 28 evts. N = 1.7 106 evts.

• data─ MC

• ; +-; 000

00; +- 0

• ; 000

+- + 7 final state

M6 (MeV)

inv.mass of +-+ 6 out of 7

R= 4.7 0.5 0.3 KLOE [Phys.Lett.B541(2002)]( +-+3 final state, 17pb-1 of 2000 data)

mixing angle By using the PDG value of Br() Br() = (6.16 0.20 0.28) 10-5

)(41.3 2.0

0.6P

3100.20)0.08(4.76ηγBr

γηBrR

syst. dominated by the uncertainties on Br(+-) and Br(00) We will measure them with 2 fb-1

BR()/BR()


Violates C, BR < 5104 @95% CLPDG ’02 (GAMS2000)

4Erecoil = 363 MeV

BR(3.6105 @ 90% CLPhys. Lett. B (591) pp. 49-54 (2004)

background estimate from the sidebands

expected signal shape

Search for


• PT: relevant terms start at O(p6)• Recent measurements of Br(0): (7.21.4)10-4 GAMS (1984) < 8.4 10-4@90% C.L. SND (2001)

(2.70.90.5)10-4 Crystal Ball (2004) • ; 0 5 final state • Large background from: (1) 5 processes: a0, f0; e+e-0 (0)(2) ; 000 with lost or merged photons

• Reject (1) with veto on , , and additional 0

• Reduce (2) by exploiting shower shape variables to identify merged clusters

• Fit to the 4 inv. mass spectrum:

735 evts selected Sign. = 68 Bkg=667

M4 (MeV)BR→ = ( 8.4 ± 2.7stat ± 1.4syst ) × 10

A clean test of chiral PT: 0


Crystal Ball(2004)

GAMS (1984)

KLOE

KLOE 1KLOE 2KLOE 3O(p6) calculations

• Factor ~ 10 less than GAMS • Only marginally compatible with Crystal Ball• Good agreement with O(p6) calculations

[1] [2] [3] [4] [5] [6] [7] [8]

0


Conclusioni

La -factory DANE fornisce un ambiente sperimentaleunico al mondo, dove si possono selezionare grandi campioni di mesoni K con un purezza ed un controllo delle sistematiche eccellenti.

KLOE sta producendo una serie di importanti misurein fisica del K ed in fisica adronica, spesso migliorando di ordine di grandezza la precisione delle misure precedenti.

Attualmente KLOE sta raccogliendo un campione di dati di dimensione almeno 4 volte superiore a quello sinora analizzato: ci aspettiamo notevoli miglioramenti delle misure già effettuate, e sensibilità a canali più rari !

IL PESODELLA

SCIENZA


SPARE SLIDES


BR(KS ())/BR(KS )Interest in KS branching ratios:

• R fixes BR(KS ()), used to normalize BR(KS e )• Opportunity to push systematics for high-precision KLOE measurements• First part of double ratio for Re /• Provides information on EM isospin breaking in K decays• Can extract 0 2 if effective E cutoff known for channel

Previous mmt: KLOE ’02 17 pb-1 ’00 data 2.236 0.003 0.015

Repeat analysis with various improvements:

• New simulation of machine background in MCReproduces effects e.g. on selection efficiency on a run-by-run basis

• Improved KL-crash simulationLeads to optimized choice of KL-crash energy cut: 100 200 MeV

• Higher statistics allow stability of result to be studied


BR(KS ())/BR(KS )

Fractional error on R

sourceerror (%)

event count 0.04stat (efficiencies) 0.12cosmic-ray veto 0.02acceptance 0.2100acceptance 0.19tag ratio (t0) 0.10trigger 0.20tag ratio (TCA) 0.20background subtraction

0.10

Total error 0.44

KLOE ’02 17 pb1 ’00 data 2.236 0.003 0.015KLOE ’05 preliminary 410 pb1 ’01 + ’02 data 2.256 0.003 0.010

R vs. running period

2.256 ± 0.0032/dof = 0.99 (45.9%)

20022.254 0.003

20012.259 0.004


Event counting checksData-MC agreement after the fit is satisfactory

Reliability of the fit result has been checked on variables not used in the fit

PID from spatial distribution of energy deposit in EmC is a valuable tool

Data— MC fitsignalbad

bad

other

50 4500

50

100

150

200

Ln(Le)/Ln(max{L,L})00

Evt

s/2.

5MeV

M (MeV)

1 00

100

300

500

2

Evt

s/0.

1

1 0 500

Data— MC fitsignalbad

bad

other


Analysis outline – efficiency estimateTwo methods for the efficiency estimate:

1. “Single-particle” method:

1. Estimate single-particle efficiencies from various sources, both in data and MC

2. Parametrize as a function of kinematical variables: Pt, Pz, P, cos , zfib

3. Use Data/MC efficiency ratio to correct MC efficiencies

2. “Double-particle” method:

1. Select prompt KL e decays, accompanied by KS

2. Evaluate the efficiency on the control sample, with attention to the trigger condition in each event

Comparison of two methods used to evaluate systematic uncertainty

Total efficiency is 20% given the tag


Systematic uncertaintiesDependence of corrections on charge state is crucial for the charge asymmetry

TOF efficiency responsible for the charge dependence:

= (4.3 ± 0.9stat ± 0.8syst)%

TOF difference arise from different hadronic interaction mechanisms for + and in EmC

Corrections studied as a function of time during data taking: the result is stable

Check fit stability and MC reliability by varying KL crash minimum energy

CorrectionCharg

e

Fractional uncertainty

Statistical

Systematic

Countinge

e

1.31%1.25%

0.5%0.5%

DC preselection

e

e

0.2%0.2%

0.4%0.4%

TCAe

e

0.04%0.04%

0.4%<0.1%

Triggere

e

0.07%0.07%

0.5%<0.1%

TOFe

e

0.3%0.3%

0.1%<0.1%

Tag bias /e

e

e

0.8%0.8%

0.1%0.1%

Efficiency for 0 0.3%

Totale

e

1.58%1.41%

1%0.6%


KS e decays – Results

Use BR(KL e±KTeV 04]:

Re(x) = (3.1 3.0stat 1.8syst) 10

Use BR(KL e±KLOE 05*]:

Re(x) = (.6 3.1stat 1.8syst) 10

Use average of KTeV and NA48 measurements of KS lifetime: S = (89.62 0.05) ps

Use new measurement of the KL lifetime: L = (50.81 0.23) ns [KLOE 05]

Compare (KS e) with (KL e): test of the S Q rule

Re(x) =1/4 [(KS e) / (KL e)1]

KTeV 04

KLOE 05*

PDG04

Most precise measurement of Re(x) (in CPT conserving transitions): compare w CPLEAR99, Re(x) = 6×103

*to be published, see C. Bloise talk in this conference

BR KLe3KLOE KS assuming S=Q

0.38

0.39

0.40

0.41


Charged kaon lifetime - 1• Vus experimental input. • 0.2% fractional accuracy; 0.1% for Vus.• Affects the BR measurement via the geometrical acceptance.

• PDG entries: discrepancies between in-flight and at-rest measurements; discrepancies between different stoppers in at-rest measurements.

• New high statistics measurement almost complete at KLOE, now under the review of the collaboration.

• Two different methods to measure .Measuring K decay lengthMeasuring K decay time

Cross check on the systematic error.


Charged kaon lifetime - 2Common to both methods: • Tag events with K2 decay• Identify a kaon decay vertex in DC fiducial volume

Tag(K2)1st method: • Measure the kaon decay length taking into account the energy loss: K = i Li/(iic)• Tracking efficiency and resolution measured on data by means of neutral vertex identification.• Fit of the K distribution.• 0.2% fractional error.

2nd method: • Use only K2 decays• Use tag information to estimate the T0 i.e. the K+K time.• Identify the clusters belonging to 0. • Measure the kaon decay time:K = (t – R/c –T0)K.• K: average over the kaon path (0.5% fractional error on K)


Aij Smearing matrix (MC)j Reconstruction efficiencyj “Bare” Ke3 decay densityFj

FSR FSR correction

Ni = N0 20

j =1Aij j j(, ) Fj

FSR

Divide data into 20 bins (3 t 7)

t

“bare” (t) MC Ke3

= 0.03 = 0

Obtained from MC generator, effect mainly at low t

e

e

Data divided into 14 periodsGood stability of resultsGood agreement for e, e

Fit to KLe3 form-factor slopes


M 2(GeV2)

KLOE data 2001Lint = 140 pb-1

its impact on a

a 11 659 000 ∙ 10-10

Experiment E821

DEHZ’03 [e+e- based]

DEHZ’03 [based]

Based on CMD-2 andKLOE-Measurements

A. Höcker @ ICHEP04: hep-ph/0410081

Theory:

New

DEHZ’04 [e+e-]

Phys. Lett. B606, 12 (2005)

Non-Kaon physics : the hadronic cross section

Exploit ISR to measure (e+e-+-) as a function of energy

Small angle photon analysis already published


500< <1300

Both pions tracks and photons are required to be in the angular region 50o-130o

The photon has to have E>50 MeV In this region we detect the photon tagged measurement

Background sources:e+e e+e-e+e

The photon tagging is essential in order to reject background

M2 [GeV2]

MC MC

50o<<130o

50o<<130o

signal extraction at large angle


Radiative Bhabhas e+e- e+e- are separated by means of a particle-ID (signature of EmC-Clusters and time of flight of particle tracks)

To reject and background a cut in the plane Mtrk vs. M

2 is applied. Mtrk is a kinematical variable obtained by solving

– MC

– MC

- MC

M2 [GeV2]

Mtr

k [M

eV]

m

m

m

0|pp|M|p|M|p|M 221

22trk

22

2trk

21

Residual are subtracted by fitting trackmass distributions with MC ones with free normalization parameters A kinematic fit rejects residual +-0

0.75 < M2<0.8 GeV2 Data

MC MC

Mtrk [MeV]

Background rejection


dN/dM2 spectrumdN/dM2 spectrum

M2 [GeV2]

KLOE Preliminary

Same KLOE published data

dN/d

M

2

The spectrum extends down to the 2-pions threshold(10 times more statistics are on tape!)

50o<<130o

50o<<130o


e+e- +- forward-backward asymmetry

Asy

mm

etry

Full = data pointstraingles = predictions

ISR+FSRSquares = predictions ISR+FSR+f0(KL)

Adding the contribution of f 0(980) parameterized according to the kaon loop model,the MC reproduces better the shape of data.

1000 900850 950 1000800800600

0

-0.1

-0.2

0.1

0.2

0.3

0.1

0.2

0.3

0.25

0.15

0.05

Asy

mm

etry

M [MeV] M [MeV]

0

0.35


Summarizing:

(1) The Kaon-Loop frame describes our entire data-set. Emerging picture:

f0(980) strongly coupled to kaons g2

fKK ~ 2 ÷ 3 GeV2; R = g2

fKK/g2f ~ 2 ÷ 4.

a0(980) is less strongly coupled to kaons g2

aKK ~ 0.4 GeV2

R = g2aKK/g2

a ~ 0.8f0(600) required in the channel

(2) No Structure analysis is promising:still theoretical effort required BUTfirst results “confirm” the kaon-loop picture:f0 and a0 have large |ss> contents.

The KLOE scalar analysis is not yet completed. However:

risultati recenti dell’esperimento kloe alla f -factory da f ne - frascati

Documents

semileptonic ks

ks p pp0

pure ks

decays ks 3p0

decays rare ks

vantages of f

f rest frame b

n bdecays