Experimental setup Data taking Vus CPT a had f 0 KLOE - May 20, 20081 The KLOE experiment at the Frascati -factory

KLOE - May 20, 2008 1

Experimental setup Data taking Vus CPT ahad f 0

The KLOE experiment at the Frascati -factory


KLOE - May 20, 2008 2

The KLOE detectorMulti-purpose detector optimized for

Klong physicsKL ~51 ps c|DAFNE ~340 cm

Huge, transparent Drift Chamber in 5.2 kGauss field of a SC coil. Carbon fiber walls, 55000 stereo wires, 2m radius, 4m long, mostly He gas mixture. Momentum resolution:(pT)/pT~0.4%

Lead-Scintillating Fiber Calorimeter with excellent timing performance.24 barrel modules, 4m long + C-shaped End-Caps for covering 98% of the solid angle. Time resolution:T = 54 ps/ E(GeV) 50 ps. Energy resolution: E/E = 5.7% / E(GeV)


KLOE - May 20, 2008 3

•2001-2005 Lint = 2482 pb-1

•2004-2005 Lint = 1990 pb-1

•Best conditions: Sept/Oct/Nov 2005 179/189/194 pb-1

stable luminosity, beam energy and backgrounds

Five years of continuous efforts to increase circulating currents maintaining low bck level at the IR and providing stable running conditions for the experiments

Continuous Beam Re-filling to obtain integrated luminosities > 150 pb-1 per month

KLOE Data Taking


KLOE - May 20, 2008 4

min {(pmiss-Emiss)|, (pmiss-Emiss)|

e

Data

• KL e: KL vertex reconstructed in DC Fit to pmiss - Emiss spectrum

• KL Photon vertex reconstructed by

TOF• Absolute BR: (Nsig/Ntag) 1/siggeo function of L

• Using the constraint BR(KL)=1,BR(K Le) = 0.4007 0.0006stat 0.0014syst

BR(K L ) = 0.2698 0.0006stat 0.0014syst

BR(K L 000) = 0.1997 0.0005stat 0.0019syst

BR(K L +-0) = 0.1263 0.0005stat 0.0011syst

KL = (50.72 0.17stat 0.33syst ) ns

Result from direct KLOE measurement, L= (50.92 0.17stat 0.25syst ) nsAverage: L = 50.84 0.23 ns / ~ 4.510-

3

PLB 632 (2006) 43PLB 626 (2005) 15PLB 636 (2006) 166

Dominant KL’s BR and L


KLOE - May 20, 2008 5

Semileptonic K± BR’sSemileptonic decays tagged by 2-body decays, K0 and K

Four different samples analyzed, tagged by K++0, K--0, K++ , K--

Lepton mass from p and TOF: M2lept

= p2lept [ c2/L2

lept (Tlept- T + L/c)2 – 1 ]

Consistent results, giving

BR(K±e3) = 0.0497 ± 0.0005

BR(K±3) = 0.0323 ± 0.0004

Event counting from the fit of the M2lept distribution with the MC-predicted

spectra for K±e3, K±

3 and background.

The measurements are fully inclusive ofradiative decays, whose acceptance is known from MC simulation [ C. Gatti, Eur. Phys. J., C 45 (2006) 417]

BR \ Tag K+2 K+

2 K-2 K-

2

BR(Ke3) 0.0495(7)

0.0493(10)

0.0497(8)

0.0502(10)

BR(K3) 0.0322(6)

0.0322(9) 0.0323(5)

0.0327(9)

JHEP 0802 (2008) 098


KLOE - May 20, 2008 6

K± Lifetime

Four independent measurements of the K± lifetime, exploiting both, -the accurate vertex reconstruction (tracking) and -the excellent time resolution of the calorimeter (TOF)

All of the decay channels tagged by K± decays have been used for the Kaon vertex reconstruction, while the X0 channels have been selected for the TOF measurement.

(K±) = 12.347 ± 0.030

Efficiencies are evaluated with data control samples.From vertex measurement we obtain (K±) = 12.364 ± 0.031stat ± 0.031syst and from TOF (K±) = 12.337 ± 0.030stat ± 0.020syst Normalized correlation, from common events (systematics are pratically uncorrelated ) is 30.7%. Averaging the results, we obtain:

K-, l

K+, l

K-, t

K+, t

JHEP 0801 (2008) 073


KLOE - May 20, 2008 7

Semileptonic form factorsForm Factor dependence from momentum transfer used in the evaluation of phase space integral

Phys.Lett.B636(2006)166

KLe

t/m2

from KL New parametrization used. Series expansion in terms of one parameter only for both, f+ and f0Combined e and results:

I(K0e3) I(K0

3) I(K±e3) I(K±

3)0.15477(35)

0.10262(47)

0.15913(36)

0.10559(48)

JHEP 0712 (2007) 105

KL


KLOE - May 20, 2008 8

BR(e) = (7.046±0.077±0.049 )10

fractional error: 1.3% = 1.1%stat 0.7%syst

AS = (1.5 ± 9.6 ± 2.9 ) 10

first measurement

Charge asymmetry

Branching ratio

1 + 4 Re(x+) = SL

BR(KS e) L

BR(KL e) S=

6 10 3

103 4 10 3

13 103

Re x = ( 0.5 3.1 1.8) 10

Pure KS beam, tagged by KL interactions in the calorimeter. TOF e/ ID, fit to Emiss- pmiss spectrum

KS events in the same sample for KS counting

PLB 636 (2006) 173

Kse: BR, As, Re x+


KLOE - May 20, 2008 9

(K l)C2K(G2

FM5K/192 ) f2

+(0)|Vus|2 I(t) SEW(1 + EM + SU(2) )

f+(0)|Vus| from Kl3 decays

Electromagnetic and Isospin corrections + phase space integrals to obtainindependent measurements of f+(0)|Vus| The consistency of the measurements validates isospin corrections

< f+(0)|Vus| > = 0.2157 ± 0.0006

< f2+(0)|Vus|2 >|

e < f2+(0)|Vus|2 >|

competitive with that obtained from leptonicdecays g2

e/g2 = 1.000 ± 0.008

is a test of lepton universality


KLOE - May 20, 2008 10

Radiative corrections largely cancel out in the ratiofK /f ratio: better precision from Lattice, scale-

uncertainties reduced Using fK /f =1.189(7) (HPQCD/UKQCD Coll.,

arXiv:0706.1726))and KLOE BR(K+ +) :

|Vus/Vud|2 = 0.0541 0.0007

Tag from K-Subtract lbackground from dataEvent count in the {225, 400} MeV window of the momentum distribution in the K rest frame

BR(K+ = 0.6366 0.0009stat 0.0015syst

PLB 632 (2006) 76

BR(K++())


KLOE - May 20, 2008 11

Unitarity test of the CKM matrix

JHEP 0804(2008)059

From KLOE average < f+(0)|Vus| > and using the recent Lattice result f+(0)=0.9644±0.0049 [ RBC/UKQCD Coll., arXiv:0710.5136],

V2us= 0.05004±0.00058

KLOE has also obtained, in agreement with Lattice results, f+(0)=0.964±0.023 from the measurement of the semileptonic form factor parameters, using Callan-Treiman relation and fk/f = 1.189±0.007

From superallowed nuclear -decay, V2

ud= 0.94903±0.00051

The fit including KLOE V2us/V2

ud determination from K++decays provide the CKM unitarity test:

1 -|Vus|2 - |Vud|2 = 0.0004 ± 0.0007


KLOE - May 20, 2008 12

Bounds on New Physics from K decayInteresting limits in tan-MH± plane have been obtained from K decayH± exchange can compete with the W± exchangefor the helicity-suppressed mode K [G.Isidori and P.Paradisi,Phys.Lett.,B639(2006),499]The observable used is

that is unity in the SM and would be lower by the interference between W± and H± amplitudes

Rl23 = 1 - m2K+ m2

+

m2H+ m2

K+

tan20tan1 -( )

Rl23 =Vus(K2) Vud(0+0

+)Vus(Kl3) Vud(2)

From KLOE measurements, lattice calculations and Vud results reported in the previous slides,we obtain

and the limits that in the figure are compared with those from B decay

Rl23 = 1.008 ± 0.008


KLOE - May 20, 2008 13

NEW: Re (159.6 ± 1.3) 10-5 Im (0.4 ± 2.1) 10-5

OLD: Re (164.9 ±2.5) 10-5 Im 2.4 ±5.0) 10-5

- Uncertainty on Im is now dominated by

and

- Semileptonic sector contributes by ~ 10%

Assuming no CPT violation in the decay amplitudes, ( = 0): |M| < 310-19 GeV

1. KLOE: new BR(KL

2. KLOE: A, x, S=Q from KSe

3. KLOE: new limit on KS3

4. No results already constrained byBSR have been used

2-3 improvement

CPT test from Bell-Steinberger relation

From Im and Re get limits on M= (mK0 - mK0) and = (K0 - K0)

JHEP 0612 (2006) 011


KLOE - May 20, 2008 14

tmeeetI ttt LSSL cos12 ;, 2/

interference term modified introducing a decoherence parameter .

038.0035.0018.0

LS KK

520.018.0 1010.000

KK

Systematics x10 better, completely negligibleKSKL

< 0.085 K0K0 < 0.44 10-5 @ 90% C.L.

CPT violation could also change initial state

|| < 2.1 10-3 @ 95% C.L.

PLB 642(2006)315

Decoherence and CPT from neutral Kaon pairs


KLOE - May 20, 2008 15

PLB 606(2005)12

2

The anomalous muon magnetic momenta = (g - 2)/2 = (116592080 ± 60) 10-11 E821Theory : a = a

QED + aweak

+ ahad

ahad from measurements of the ha-

dronic cross section via dispersion relation

Dominant low-energy contribution, M2< 1 GeV2

KLOE measurement from e+e- final state with at low zenithal angleWe obtained a

in the 0.35<s< 0.95 GeV2 region.Two independent data sets have been analyzed with different trigger conditions and different analysis paths, giving

Hadronic cross section

a|0.35<s<0.95 = (3844± 8stat± 35syst± 35theo) 10-11 [140 pb-1 data sample]

a|0.35<s<0.95 = (3892± 6stat± 30syst± 20theo) 10-11 [242 pb-1 data sample]

(preliminary)


KLOE - May 20, 2008 16

Low-energy hadronic contribution to a

Consistent set of avalues from all of

the low-energy hadronic cross section measurements at e+ e- machines

The theoretical SM prediction for aincluding the e+ e- data set differs bymore than 3from the BNL measurement

New KLOE analysis confirms the discrepancyK. Hagiwara, A.D. Martin, Daisuke Nomura, T. Teubner


KLOE - May 20, 2008 17

Search for the f0 signal as a deviation on M from the ISR + FSR shape

f0(980) region

M (MeV)

S

e+e

Two main contributionsto the final state,separated in thebi-dimensional plot Mvs M

Eve

nts/

1.2

MeV

e+e events with the photon at large angle (45<<135)Main contributions: ISR (radiative return to ) and FSR

e+e

The light scalars : f0 (980)


KLOE - May 20, 2008 18

SgKK

gSKK

gS

K

K

SV gVS

gS

e+

e-

Kaon-loop

Predictions of the M distribution from Kaon-loop and direct scalar coupling to vector mesons, have been compared for both final states, , and

PLB 634 (2006) 148

EPJ C49 (2007) 473

Experimental distributions have been fitted taking into account the contributions to the final states summarized in the previous slide

Data can be described by both the models

To fit the spectrum with predictions from Kaon-loop model, a (600) contribution must be included

KK coupling, in the model with direct scalar coupling to vector mesons, results weaker from analysis than in the study.

The f0(980) structure

Documents

Experimental setup Data taking Vus CPT a had f 0 KLOE - May 20, 20081 The KLOE experiment at the Frascati -factory