KLOE @ FlaviaNet Orsay07
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Transcript KLOE @ FlaviaNet Orsay07
Gruppo I
KLOE
17 Dicembre 2007
The KLOE experiment at DANE
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)
fK+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
GK
4) KSKL interferometry
precise measurements
e2
)/GK
*
*
)
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
Km3
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
8.5106 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
13106 tagged, events
present
achievements
Improve to ~ 0.3% with 5 avail. statistics (work in progress)
BR(KS en)
BRs from KLOE tagged KS beam, 1.2108 events
(20% of full data sample)
KLOE
PLB 632 (2006)
BRKS en/BRKS = 10.19(13) 10-4
KLOE
EPJC 48 (2006)
BRKS /BRKS = 2.2459(54)
Averaged with KLOE ‘02
These two measurements completely determine main KS BRs
BRKS en= 7.046(91) 104
AS = (1.5 9.6stat 2.9syst)
103
present
achievements
With 2.2 fb1 we will measure:
BR: stat error will be 0.5%
goal
need to improve on the present syst. (0.7%) 6103
AS: dominated by stat
4103
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(Ke3 ) and BR(Km3 ), tagging with
K mnand K :8 measurements in total, each with 105
KLOE final
ArXiv: 0707.2532
BRKe3= 4.965(52)%
BRKm3= 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(Kl3) by NA48, ISTRA+, E865
• Tag with Kmn 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 K2
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(K2)
• using KLOE BR(K2)
4.9
KLOE
NA48/2
ISTRA+
• using PDG06 BR(K2)
• using KLOE BR(K2)
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/, Kand Km2 measured recently
- Kl3 and highly correlated in fit
- New measurement of is crucial KLOE prel.
BR(K 0en)
PDG ’04
PDG ’06
Kaon07
BR(K mn)
PDG ’04
PDG ’06
Kaon07
BR(K 0mn)
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 (m2).
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) 0.410-3
In MSSM, LFV can give up to % deviations
[Masiero, Paradisi, Petronzio]
NP dominated by contribution of ent
RK
ne nmnt
G(Kene)+G(Kent)
G(Kmnm)
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→eve00
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
K3 hypotesis
4-momentum conservation
0 invariant mass
Ke4 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 000decays
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 (=-0.0310.004);
’ 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 (KL0).
• 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 KL0 and KL nuclear
interaction) allow to extend the fit range
(at least 27 ns instead of 24.8 ns)
• Data
KL30
KL nucl.int.
KLm3
KLe3
KL20
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