hadronic results from kloe
DESCRIPTION
European Physical Society International Europhysics Conference on High Energy Physics EPS (July 17th-23rd 2003) in Aachen, Germany. Hadronic results from KLOE. E. Santovetti (INFN – Roma II) for the KLOE Collaboration. DA F NE: the Frascati F factory. - PowerPoint PPT PresentationTRANSCRIPT
Hadronic results from KLOEHadronic results from KLOEE. Santovetti (INFN – Roma II)
for the KLOE Collaboration
European Physical SocietyInternational Europhysics Conference
on High Energy PhysicsEPS (July 17th-23rd 2003) in Aachen, Germany
E. Santovetti
DANE: the Frascati factory
HEP2003 Aachen, 17-23 July 2003
electron positron collider at the mass energy (ECM= 1020 MeV)
separate rings to minimize beam-beam interaction
two interaction points (KLOE – DEAR/FINUDA)
Machine parameters Design 2002
Total length (m) 98
Max. bunches 120 51
Bunch spacing (ns) 2.7 5.4
Lifetime (min) 120 40
Bunch current (mA) 40 20
L single bunch (cm-2 s-1) 4.4 1030 1.5 1030
L peak (cm-2 s-1) 5.3 1032 0.75 1032
per year (109) 15 0.9
E. Santovetti HEP2003 Aachen, 17-23 July 2003
KLOE data taking history
Yearpb-1/day
average peak
2000 25 pb-1 0.1 0.4 First published results
2001 170 pb-1 0.7 1.8Luminosity improved but high background
Further analyses published
2002 280 pb-1 2.0 4.5Higher luminosity and background reduced
Analysis in progress
An upgrade of the machine has been done. An increase in luminosity ( > x2 )is expected in the next data taking.
in 2002 31 2 17.8 10peakL cm s
Ldt
E. Santovetti
Kaon physics at DANE
HEP2003 Aachen, 17-23 July 2003
• The kaons are produced in pairs (K+ K- and KS KL ) with opposite momentum.
• The detection of a kaon on one side can be used to tag the other kaon in the opposite side
• Measure of absolute branching ratios
• Interferometry studies on KS KL system
e- e+
KL
KS
p (MeV/c) l (cm)
K+ K- 127 95
KS 110 0.6
KL 110 343
all KS decay close to the IPreasonable acceptance for KL
( ) 3e e b F decay % #/pb-1
K+ K- 49.2 1.5x106
KS KL 33.7 106
15.5 5x105
1.3 4x104
E. Santovetti HEP2003 Aachen, 17-23 July 2003
The KLOE detector
Electromagnetic calorimeter lead/scintillating fibers structure 15 X0 thickness 4880 PMT's
Drift chamber (4m Ø x 3.3m) 90% He – 10% IsoB mixture (X0 ~ 500m) 12582/52140 sense/total wires stereo geometry for z measurement
Quadrupole calorimeter lead/sc. tiles calorimeter surrounding the permanent quadrupoles (32 PMT's)
Superconducting coil (5m Ø) B = 0.52 T
E. Santovetti HEP2003 Aachen, 17-23 July 2003
Detector performancescalorimeter
Drift chamber
/ 5.7% / ( )E E E GeV
54 / ( ) 50t ps E GeV ps
High efficiency for low energy photons
, 150x y m 2z mm
/ 0.4% ( 45 )p p
E. Santovetti HEP2003 Aachen, 17-23 July 2003
KLOE physics program
1999
2000
2 pb–1
20 pb–1
200 pb–1
2 fb–1
2002
KS , KS 3, KS KL 2, KL Vus from K± and KL decays K± branching ratios (e+e– –) to 1%
radiative decays f0 , a0 scalar ’, pseudoscalar KS decays BR(KS –)/BR(KS ) BR(KS e) first published results
500 pb-1 now on tape
Discrete symmetries Re() via double ratio (CP direct) KLKS Semileptonic asymmetry (CPT) KLKS interferometry
E. Santovetti HEP2003 Aachen, 17-23 July 2003
mass and width
line shape has been fitted for the main decays
W(MeV)
- -
2 20
2 2 2 2( )
( - )e e X e e X
ms
s m m
+ corrections (phase space + contributions from )
K+K– 49.2%KLKS 33.7% 15.5% 1.3%
parameters:mass, total width, peak cross sections
K+K–
KSKL
In the case of a fit with several points has been used to find the correct line shape form (interference between direct, and )
With a combined fit, we measure the width: 4.19±0.04 MeV (preliminary)
(Mass is calibrated with the CMD-2 value)
E. Santovetti HEP2003 Aachen, 17-23 July 2003
Neutral kaon mass KLOE can study masses of particles with high accuracy thanks to excellent drift chamber momentum resolution
Neutral kaon mass can be measured using KS
22 2
2
4
0.05
K K
K K K K
K K K K
WM P
M P P P
M M P P
W (MeV)
(e
+e
-
KSK
L) (
b)
KSKL
KS
Energy scale from CMD-2 mass value
MKs=497.583±0.005stat±0.020syst MeV*PDG: 497.648±0.022 MeV
*KLOE Note 181 (http://www.lnf.infn.it/kloe/)
2001Energy scan
KS is tagged by identification of KL in the calorimeter (KL crash): a neutral cluster in a fixed time window
• efficiency ~ 30% ( largely geometrical)• angular resolution on tagged KS ~ 1°• momentum resolution ~ 2 MeV
E. Santovetti HEP2003 Aachen, 17-23 July 2003
KS/KL tagging
KL is tagged by identification of the KS - decay: a vertex near the interaction point with the kaon inv. mass
• efficiency ~ 70%• angular resolution on tagged KL ~ 1°• momentum resolution ~ 2 MeV
(KS)/(KS)• Can be used to extract phase shifts and K amplitudes
• Provides information on isospin symmetry breaking from EM terms Chiral pert.
theory
• First part of the double ratio
0 2
0 2
2
0 2
00 0 2
0 2
2 1
3 3
1 2
3 3
3
4
i i
i i
i
A A e A e
A A e A e
A A e
From the K decays (KS, K+), in the exact isospin symmetry hypothesis, we have:
E. Santovetti
considering the EM correction:
( )i ii ii i i
EMi i i i
Ae A A e
K decays measure
To extract , we need a theoreticalinput EM.Important to know the effective E cutoff in decay
(KS)/(KS)
E. Santovetti HEP2003 Aachen, 17-23 July 2003
KS
at least 3 neutral clusters in time Ecl> 20 MeV, |cos| < 0.9 to reduce machine Bkg Efficiency ~ 90%
KS
2 tracks from IP extrapolated to the EmC (120 MeV <pTRK < 300 MeV) Efficiency ~ 60%
The measurement is fully inclusive in the radiated photon energy (no cut in the invariant mass)Efficiency is corrected for the radiated photon in the final state by folding the MC distribution (linear interpolation) with the photon spectrum theoretically predicted 0.3% effect
MC
MC
(KS)/(KS)
E. Santovetti HEP2003 Aachen, 17-23 July 2003
KLOE ‘02
KLOE '02 2.236 0.003 0.015
17 pb-1 2000 data
PDG ’02 2.197 0.026 World average
KLOE (KS)/(KS) 47.8±2.8
47.7±1.5**PDG '02
(KS)/(KS)56.7±8.0
*
Physics Letters B538 (2002)
*Cirigliano et al. (2000)
**G. Colangelo et al. (2001)
( )SK MC ( )SK ev MCCut on time of flight:
, 1 2( ) ( )
( ) ( )
, ,
t ab t a t b
t i i i
d m m
m t L m c
a b e
The mass hypothesis m=me and m=m on both tracks allows to discriminate a large part of background
E. Santovetti HEP2003 Aachen, 17-23 July 2003
KSe+, e-
Together with the KLe can be used to strictly test CPT and the S=Q
Provides information about Vus
• Difficoult to isolate Kse respect to the more abundant (x1000) Ks best measurement CMD-2: BR(Kse) = (7.2 ± 1.4) x 10-4 (75 events)
E. Santovetti HEP2003 Aachen, 17-23 July 2003
KSe+, e-Use of variable Emiss-cpmiss
For e decays this is the neutrino mass, while for the decays a value larger than zero is expected.
A fit of the data to the sum of the signal and background spectra simulated by MonteCarlo allows to extract the number of events.
KLOE preliminary (170 pb-1 '01 data)
BR(e+) 3.46 ± 0.09stat ± 0.06syst
BR(e-) 3.33 ± 0.08stat ± 0.05syst
BR(e) 6.81 ± 0.12stat ± 0.10syst
6 7 8 ×10-4
CMD-2 ’99
PDG eval. from KL
KLOE ’02* (17 pb-1 2000 data)
KLOE ’03 preliminary
*Physics Letters B535 (2002)
E. Santovetti HEP2003 Aachen, 17-23 July 2003
K0e, CPT and S=Q0
0 * *
0
0 * *
| |
| |
| |
| |
W
W
W
W
e H K a b
e H K a b
e H K c d
e H K c d
KLOE preliminaryAS = (19 ± 17stat ± 6syst) x 10-3
First measurment of AS !
,
( ) ( )
( ) ( )S L
e eA
e e
AS = AL if CPT conserved
AL
PDG '02 (3.33 ± 0.14) x 10-3
KTeV '02(3.322 ± 0.058 ± 0.047) x
10-3
Re(x) (x 10-3)
KLOE preliminary
3.3 ± 5.2 ± 3.5
CPLEAR '98-1.8 ± 4.1 ±
4.5
CPT: b = d = 0
SQ transitions are forbidden at lowest order in the SM
1Re
2
e eS Le e
S L
x
0*
0
( )
( )
A K lx c a
A K l
S=Q: c = d = Re(x) = 0
Re( / )S LA A b a
E. Santovetti HEP2003 Aachen, 17-23 July 2003
(KL)/(KL)• Provide information about the absortive contribution (Aabs) to the KL decay
(long-distance term) – Prediction on Ks• Very sensitive to the calorimeter performance in reconstructing the neutral vertex
• very clean signals: low background (KL)KL
• inclusive measure: at least four neutral clusters in time with E > 20 MeV• Efficiency > 99%
• Background ~ 0.4% (KL)
KL• Close kynematics: cuts on - E*
tot, Collinearity, Invariant mass
• Efficiency ~ 80%• Background negligible(KL)/(KL) (x10-3)
KLOE '03* 2.793 ± 0.022stat ± 0.024syst
NA48 '02 2.81 ± 0.01stat ± 0.02syst
PDG '02 2.82 ± 0.08 *Physics Letters B? (2003)
invariant mass plot after the cut on collinearity and total energy
362 pb-1 of data analysed('01+'02 data)
Preliminary1/10 of 362 pb-1
L (ns)
51.7 ± 0.4PDG '02
51.5 ± 0.4KLOE
KL
E. Santovetti HEP2003 Aachen, 17-23 July 2003
KL charged (very preliminary)
Very preliminary78 pb-1 ’02 data
*Errors are statistical only!(including MC statistics)
Systematic errors also ~1-2% but not yet fully evaluated
Pmiss - Emiss in or hyp. (MeV)
e
KLOE* PDG ‘02
KL 0.1320.002 0.12570.0019
KL 0.2710.002 0.27170.0025
KLe 0.3840.002 0.38780.0027
KL (2.020.19)·10-3
(2.0810.026)·10-
3
E. Santovetti HEP2003 Aachen, 17-23 July 2003
K± (') • Direct CP violation in the charge asimmetry (from theory 10-6 ÷ 10-
4)
• Dalitz plot parameters (CP)
• Extract isospin amplitudes and phase shifts for K decay (PT)(') best value (PDG '02) has ~2% error and concerns only K+
0 0
– K–
K++ 0
Selection/0 – tagging and self-triggering 2-tracks vtx in DC volume p* < 135 MeV/c 4 clusters ontime @ vtx (t<4) Etot < 450 MeVBackground: main K± decays, Ke4’
Efficiencies evaluated from data by using control samples(ex. cl from K±)
E. Santovetti HEP2003 Aachen, 17-23 July 2003
K± (')
BR(K±±00) (%)
KLOE '03* 1.781±0.013stat±0.016syst
PDG '02 1.73±0.04
187 pb-1 event counting (~80000 ev.)250 pb-1 efficiency estimate
si=( PK–Pi )2
s0=isi/3 ;
X=(s1–s2)/m2
Y=(s3–s0)/m2
KLOE* (6.3 pb-1) PDG '02
g 0.586±0.010 ±0.012 0.652±0.031
h 0.030±0.010 ±0.013 0.057±0.018
k0.0055±0.0026
±0.00180.0197±0.005
4
*KLOE Note 187
Preliminary Dalitz plot analysis:F(X,Y) = 1+gY+hY2+kX2
Charge asimmetry analysis in progress
E. Santovetti HEP2003 Aachen, 17-23 July 2003
Vus determination
For Ke3 modes:
0
0
20
1
2
1
BR
BR
2
1
f
f
V
V
us
us
exp th
|Vus| = 0.2196 ± 0.0019exp ± 0.0018th
Introduced in 1963, known to 1.5%
Experimental inputs to Vus from PDG 02
Mode BR(%) 103 103
K+e3 4.87 ± 0.06
28.5 ± 2.1
K0e3
38.79 ± 0.27
29.1 ± 1.8
K+3 3.27 ± 0.06 3.3 ± 1.0 4 ± 9
K03
27.18 ± 0.25
3.3 ± 0.5 27 ± 6
L = (5.17 ± 0.04) · 10-8 sS = (8.9598 ± 0.0007) · 10-11 s + = (1.2384 ± 0.0024) · 10-8 s
KLOE preliminary BR’s confirm previous values for K0
e3, K03
KLOE will have BR(Ke3) soon
KLOE will measure all BR’s to < 1% and can also significantly improve , , L
preliminary
E865
E. Santovetti HEP2003 Aachen, 17-23 July 2003
Dane produces 5·105 0 events/pb-1 ,allowing a detailed study of the decay dominated by the intermediate state: mass measurement (CPT)
Selection 2 charged tracks with vtx at I.P. |Mmiss– M° | < 20 MeV (0 mass) 2 photons (cos * < –0.98) (collinearity) 2 = (Etot- M )2/E
2 + (M-M°)2/M2 < 8
Efficiency ~ 30% - Negligible background
A : 3 terms : M+, M–, M0 and (Gounaris Sakurai shape)A : standard Breit WignerAdir: constant ad ei
d : |ad|2 = |Adir|2 / |A|2
Fit of the Dalitz plot considering a direct decay together with (dominant) and intermediate staes:
0
0
22 2
( , )
dir
p pA X Y A
A A A A
aaaaaaaaaaaaaaaaaaaaaaaaaaaa
E. Santovetti HEP2003 Aachen, 17-23 July 2003
2×106 events analyzed (16 pb–1 – 2000 data)
X=(E+– E–)/3Y=(E°– M°)
KLOE* (6.3 pb-1) PDG '02
M (MeV) 775.8 0.5 0.3 771.1 0.9
(MeV) 143.9 1.3 1.1 149.2 0.7
m0-m± (MeV) 0.4 0.7 0.6 0.4 ±0.8
m+-m- (MeV) 1.5 0.8 0.7
ad 0.78 0.09 0.13
a(7.1 0.6 0.8)×10–3
Relative decay intensities from integration of |A|2 over Dalitz plot
I = 0.937
Idir = 0.0085
I = 0.0002 I + Idir + I 1 (+6%)
Interference between and direct decays
*Physics Letters B561 (2003)
Very different valuesdepending on the used techniques:e+e-, decay, hadronproduction
E. Santovetti HEP2003 Aachen, 17-23 July 2003
Conclusions and outlook
DANE luminosity has been continuously improving. KLOE expects to collect at least 1 fb-1 in 2003/2004
Analysis of 2000-2001 data brought to several published results on neutral kaons and decays
Work in progress with 2001/2002 data:
- K , KL semileptonic decays (Vus)
– Rare kaons decays: KS , KS 3, KS e+e, KS
– decays (about 2×107 produced in 500 pb-1)