Transcript KLOE @ FlaviaNet Orsay07

Gruppo I
KLOE
17 Dicembre 2007
The KLOE experiment at DANE
DAFNE @ Frascati Laboratories
• e+e- collider with 2 separate rings:
s = Mf= 1019.4 MeV
• Luminosity up to 1.5×1032 cm-2s1
• 2 interaction regions
1. KLOE
2700 pb-1
2. DEAR (kaonic atoms)
100 pb-1
FINUDA (hypernuclei)
1100 pb-1
KLOE STATUS:
 March 2006: end of KLOE data taking
2500 pb-1 on-peak  8 × 109 f decays
200 pb-1 off-peak (energy scan+1 GeV run)
 Dafne test in progress
KLOE physics program
Kaon physics: CP and CPT violation, CKM unitarity, rare decays, ChPT tests
Hadron physics: lowest mass pseudoscalar, scalar and vector mesons
Hadronic cross-section below 1 GeV: hadronic corrections to g-2
List of the f decays: branching ratios and number of events “on tape”
B.R.
Nev KLOE (2.5 fb-1)
fK+KK0K0 KSKL



’
0.49
0.33
0.15
1.3  10-2
1.2  10-3
6.2  10-5
3.7  109
2.5  109
1.1  109
9.7  107
9.0  106
4.6  105
Initial State Radiation e+e- 
Two body decays: we can tag the event
The KLOE detector
A large drift chamber
A hermetic calorimeter
A solenoidal superconducting coil
Drift Chamber (He-IsoBut.
 ( p )
p
2m × 3m)
 0.4%
E.M. Calorimeter (lead-scintillating fibres)
E
5.4%
55 ps

t 
 130 ps
E
E (GeV )
E (GeV )
Magnetic field (SuperConducting Coil)
= 0.52 T (solenoid)
Kaon decay
Naples:
Ambrosino, Massarotti, Meola, Saracino
Forthcoming papers
waiting for referee comments
1) KLm3 ff: submitted to JHEP
2) KLe3 decay: submitted to PLB

+
3) K lifetime
Naples
paper written, under the review of the collaboration
4) BR(KS  ) *

5) BR(K+e3), BR(K+m3)
paper in writing
6) Vus with KLOE data

precise measurements
Naples
* whole data sample
Preliminary results

1) BR(K+  )
Naples
2) Upper limit on BR(KS  e+e )
3) Measurement of
GK
4) KSKL interferometry

precise measurements
e2
)/GK
*

*
)
m2
*
* whole data sample
Vus from KLOE Kl3 data
% err
KLe3
0.21547(72)
0.34
KLm3
0.21661(93)
0.43
summer conf.
Vus f+(0)
KLOE Avg: 0.21556(59)
c2/ndf = 6.1/4 (19%)
KSe3
0.21522(145)
0.68
World Avg: 0.21664(48)
K±e3
Km3
0.21465(137)
0.21302(155)
0.64
0.73
+0.2% with
final lifetime
f+(0)=0.961(5)
RBC/UKQCD, 07 prel.
 Vus = 0.2243(13)
Vud = 0.97372(26)
PRL96 032002,2006
 1-Vud2-Vus2 = 154(79)10-5
Vus f+(0): what’s missing on the experimental side
world average @EPS07
KL lifetime (and branching ratios)
Lifetime: measurement from a sample of
8.5106 KL events; uniform
reconstruction efficiency over 0.4tL.
KLOE, PLB 626 (2005)
tL = 50.92(30) ns
Absolute BRs: KL decays tagged by KS
KLOE, PLB 632 (2006)
BR(0)Ke3= 0.4049(21)
BR(0)Km3= 0.2726(16)
BR(0)3= 0.2018(24)
BR(0)= 0.1276(15)
at tL(0) = 51.54
ns
13106 tagged, events
present
achievements
Improve to ~ 0.3% with 5 avail. statistics (work in progress)
BR(KS en)
BRs from KLOE tagged KS beam, 1.2108 events
(20% of full data sample)
KLOE
PLB 632 (2006)
BRKS  en/BRKS  = 10.19(13)  10-4
KLOE
EPJC 48 (2006)
BRKS  /BRKS  = 2.2459(54)
Averaged with KLOE ‘02
These two measurements completely determine main KS BRs
BRKS  en= 7.046(91)  104
AS = (1.5  9.6stat  2.9syst) 
103
present
achievements
With 2.2 fb1 we will measure:
BR: stat error will be 0.5%
goal
need to improve on the present syst. (0.7%)  6103
AS: dominated by stat
 4103
Km3 form factor slopes
• Standard method: fit t-spectrum, t = (pK-p)2
• Difficult /m separation at low energy
• Fit En spectrum (loss of sensitivity)
K BR and lifetime measurements
Absolute BR(Ke3 ) and BR(Km3 ), tagging with
K  mnand K  :8 measurements in total, each with 105
KLOE final
ArXiv: 0707.2532
BRKe3= 4.965(52)%
BRKm3= 3.233(39)%
at t(0) = 12 .385 ns, with
dBR/BR = 0.5dt /t
K lifetime using two different methods:
t from the K decay time, using
t from the K decay length,
   decays

from
K
using tagged vertices in DC
t= 12.367(44)(65) ns
KLOE preliminary
ArXiv: 0705.4408
t= 12.391(49)(25) ns
t= 12.384(48) ns
Combined result, = 0.34
Final result: Dt/t = 0.25%
K± lifetime: experimental picture
PDG
average
12.385(25) ns
S = 2.1
Poor consistency
Needs confirmation
Discrepancy between
in-flight and at-rest
measurements
Discrepancy among
different stoppers in
at-rest measurements
Confirmation is needed
tPDG = (12.385± 0.024) ns
Method #2: proper time fit
t= 12.391(49)(25) ns
16-30 ns
~ 1l
>2l
t from the K decay time, using 
from K   decays
KLOE preliminary
ArXiv: 0705.4408
t= 12.367(44)(65) ns
t= 12.384(48) ns
T*(ns)
t from the K decay length,
using tagged vertices in DC
Combined result, = 0.34
Final result: Dt/t = 0.25%
Measurement of the BR(K++0)
PDG fit ‘06 BR(K±±0) = (20,92 ± 0.12)% DBR/BR = 0.6%
CHIANG ’72 BR(K±±0) = (21,18 ± 0.28)% DBR/BR = 1.3%
this decay enters in the normalization of BR(Kl3) by NA48, ISTRA+, E865
• Tag with Kmn decays.
• Determine the momentum of the
charged decay particle in the kaon rest
frame assuming m: p*.
• Selection efficiency measured on data.
• Count K+ events fitting p*
distribution with three contributions: mn
and 0 peaks from data control
samples, 3-body decays from MC.
ev/bin
N(fit) = 818347±1912
Ntag = 12113686
BR(K+  +0() = (20.658 ± 0.065stat± 0.090syst)%
1.3% respect to PDG 06
rel ~ 0.5%
KLOE preliminary
ArXiv: 0707.4631
p*(MeV)
Impact of the new BR(K++0)
Impact of the KLOE preliminary
measurement wrt PDG06 fit value
on the BR(K±l3):
- measurements normalized to K2
decays
- comparison with absolute
BR(K±l3) measurements from KLOE
0.214
0.212
0.21
0.208
0.206
5.2
BR(Ke3)
3.4
5.1
BR(Km3)
3.3
5.0
• using PDG06 BR(K2)
• using KLOE BR(K2)
4.9
KLOE
NA48/2
ISTRA+
• using PDG06 BR(K2)
• using KLOE BR(K2)
3.2
3.1
KLOE
NA48/2
Need to close K BRs
• Not possible to fit only new K data (unlike KL) @ KAON07
• Only Kl3, Kl3/, Kand Km2 measured recently
- Kl3 and  highly correlated in fit
- New measurement of  is crucial KLOE prel.
BR(K  0en)
PDG ’04
PDG ’06
Kaon07
BR(K  mn)
PDG ’04
PDG ’06
Kaon07
BR(K  0mn)
PDG ’04
PDG ’06
Kaon07
Fit rests heavily on
Chiang (no radiative
corrections, 6 BR
constrained by
SBR=1, correlations
not available).
BR( needed to
remove Chiang
BR(K  0)
PDG ’04
PDG ’06
Kaon07
KLOE
in
progress
BR(K)
• PDG fit ‘06: DBR/BR = 0.5%; CHIANG ’72: DBR/BR = 3.6%
• Signal: require two tracks making a vertex along the K path beforeDC
• Look for the signal in the missing mass spectrum (m2).
MC
K  +-+
K  0
K  mn
Ke3
Km3
other
data
MC
Expect stat ~ 0.1%
(work in progress)
Mmiss2 (Mev2)
Lepton universality from Ke2/Km2
SM: no hadronic uncertainties (no fK)  0.410-3
In MSSM, LFV can give up to % deviations
[Masiero, Paradisi, Petronzio]
NP dominated by contribution of ent
RK
ne nmnt
G(Kene)+G(Kent)
G(Kmnm)
with effective coupling:
RK  RKSM[ 1+
mK4
mt2
mH4
me2
|DR31|2 tan6]
1% effect (DR31 ~5x10-4, tan mH~500GeV) not unnatural
Present accuracy on RK @ 6% ; need for precise (<1%) measurements
LFV in Ke2 decay
KLOE preliminary result @ KAON07 (8k evts, 2.7% uncertainty)
RK= 2.55(7)10-5
ArXiv: 0707.4623
ArXiv:
0707.4623
Will push error to ~1%: final result will be compared with P326/NA62
measurement (more than 100k events already acquired)
K→eve00
Considering kaon decays with two 
K X 0 X 
Ee,xe,te
We look for two vertex asking
 clusters on time:
(t - r/c)1 = (t – r/c)2

invariant
pK
tm
Kmn tag
mass
 agreement between kaon flight
time and clusters time
Charged vertex in FV
xK
e±
lK
t0 pK
0
0
E,t,x
E,t,x
E,t,x
E,t,x
K00e4 BR: Kinematic fits
K3 hypotesis

4-momentum conservation

0 invariant mass

Ke4 hypotesis

missing 4-momentum
having zero mass

0 invariant mass

clusters on time
clusters on time

f


f
Radiative decay
Naples:
Ambrosino, Capussela, Di Donato, Perfetto

Results on pseudoscalar mesons
waiting for referee comments
Measurement of the  mass
*
paper written, under the review of the collaboration

Dynamics of  000decays
Naples
Dynamics of  + -0decays
Naples
precise measurements
* whole data sample
Precision measurement of the mass
Motivated by the discrepancy
between the two best measurements:
NA48 (2002)
M() = 547.843 ± 0.030 ± 0.041 MeV
GEM (2005)
M() = 547.311 ± 0.028 ± 0.032 MeV
(D >10 , PDG average gives a scale
factor of 5.8 !)
Recently a new measurement has
been published by CLEO:
CLEO (2007)
M() = 547.785 ± 0.017 ± 0.057 MeV
Precision measurement of the mass
KLOE method: analysis of fully
neutral 3 events
f with 
f with 
3 clusters in the calorimeter only.
Kinematic fit with 4 constraints
==> energies by cluster positions
Discrimination between  and 
very easy from Dalitz plot.
Absolute energy scale from the e+ecenter of mass energy s
(kinematic fit input) - calibrated
comparing M(f) obtained by the
energy scan to the PDG value
(dominated by CMD-2)
KLOE final result:
M() = 547.873 ± 0.007 ± 0.031 MeV
Dynamics of the 3 decay
'3 decay  isospin violation in strong interactions
mu  md  ms
A test of low energy effective theories of QCD
KLOE has studied with high statistics the dynamics of both channels:
(a)    Dalitz plot analysis: 1.34 106 events
(b)    ”slope” analysis:
0.65 106 events
Dynamics of the 3 decay
(a)    Dalitz plot:
- large statistics
- negligible background
- use X and Y variables
Fit results of the    Dalitz plot
Including systematic errors
a=-1.090  0.005 +0.008 -0.019
b= 0.124  0.006  0.010
d= 0.057  0.006 +0.007 -0.016
f= 0.14  0.01  0.02
Comments:
0. the odd terms (c and e) in X are compatible with 0 (no asymmetries);
1. the quadratic term in X (d) is unambiguosly different from 0;
2. the cubic term in Y (f) is needed to get an acceptable fit;
3. the b=a2/2 (current algebra rule) is largely violated.
Fit results of the    ”slope”
The slope is evaluated by comparing the z distribution of the
data with a Montecarlo simulation with =0 (pure phase space)
 High sensitivity to the M() value (Dalitz plot contour)
MC with M()=547.3
MC with M()=547.822
New (preliminary) result:  = -0.027  0.004 +0.004 -0.006
 in agreement with Crystal Ball (=-0.0310.004);
’ gluonic content
KLOE analysis uses the constraints:
J.L.Rosner, Phys.Rev. D27 (1983) 1101,
A.Bramon et al., Phys.Lett. B503(2001) 271
E.Kou, Phys.Rev.D63(2001) 54027
Y1: G’/G
Y2: G’/G
Y3: R
Y4: G’/G
A >3 effect is found:
Z2’ = 0.14  0.04
fP
= (39.7  0.7)o
R.Escribano, J.Nadal (JHEP 0705,006,2007) reanalyze all V P and P V decays
updating wavefunction overlaps parameters and neglecting the Y1 constraint
 no evidence of gluonium content
Conclusions
Kaon and hadronic physics allows
for precision SM tests
(and beyond)
Spares
KL lifetime: update with 2 fb-1
• Same technique used for the
measurement on 2001/2002
data (KL0).
• Factor ×5 in statistics: at
least a factor 2 better wrt the
published stat. error (0.17 ns)
• Syst. error dominant (0.25
ns). Aim to at least a factor 2
better.
• Bkg less than 1%, in FV.
1) Improve quality of the neutral vertex
algorithm (better agreement wrt MC).
2) Improve clustering algorithm
3) Study of background at the edge of
FV (mainly KL0 and KL nuclear
interaction) allow to extend the fit range
(at least 27 ns instead of 24.8 ns)
• Data
KL30
KL nucl.int.
KLm3
KLe3
KL20
KL regen.
KL
Proper time (ns)
Searching for Ke2 @ KLOE (I)
BR(Ke2)≈2x10-5, expect 4x104 events in KLOE data sample (2.3 fb-1)
perfom direct search for Ke2 without tag  gain ×4 of statistic
search for a vertex inside the Fiducial Volume (40<xy<150) cm
cuts on track quality for K± and secondary tracks, cuts on vtx quality
B/S(-3000.<M2lep<3000.) ≈ 10.
kaon momentum is measured with 1% resolution
close kinematics we get Mlep
M2lep(MeV)2
Searching for Ke2 @ KLOE (II)
PID exploits the granularity of KLOE EmC shower profile along the particle path
variables used: E2RMS = Si=1..N(E(i)-<E>)2/N, E/P, cluster shape
B/S(-3000.<M2lep<3000.) ≈ 2.
signal efficiency 0.647(6)
background rejection ~ 300
Ke2 signal event counting
Ke2 event counts: likelihood fit of Mlep vs ERMS
input: MC shapes for Ke2() and background
fit parameters: # of Ke2 and background, get 8090±160 observed evts
ERMS (MeV)
Data
● Data
° MC Fit
- MC bkg
1200
800
400
ERMS (MeV)
0
40
80
120
800
Fit region
400
M2lep (MeV2)
0
M2lep (MeV2)
-4000
-2000
0
2000
correct for ratio of Ke2 and Km2 trigger and vtx efficiencies, and for PID Ke2 efficiency
4000