Analysis of ratio BR( K 0 )/BR(K )
description
Transcript of Analysis of ratio BR( K 0 )/BR(K )
![Page 1: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/1.jpg)
M. Martemianov, ITEP, October 2003
Analysis of ratio
BR(K 0)/BR(K )
M. Martemianov
V. Kulikov
Motivation
Selection and cuts
Trigger efficiency
Signal and Background fit
Selection efficiency
Result and conclusion
![Page 2: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/2.jpg)
M. Martemianov, ITEP, October 2003
Motivation / I
2A
23)A(K
, 2
A32
0A
31 )A(K
,2
A6
10
A3
1-)A(K
0
000
0
ChPT theory for K decays gives total amplitude as mixture of two isospin (I=0 and I=2) amplitudes :
CPM (chiral pole model) predicts amplitude A(K+ + 0) by formula2)/22m-2
K(m)0(cos sin)A(K 0 ffccFGCPM
PDG values : GF = 1.16610-5 GeV (Fermi constant)
sinc = 0.2196 and cos c = 0.9734 (c - Cabibbo angle)
f+(0) = 0.96 and f = 93 MeV
GeV810764.1)A(K 0 CPM
![Page 3: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/3.jpg)
M. Martemianov, ITEP, October 2003
Motivation / II
RFPK
MallK
KBRtot /28exp)A(K
00
Using PDG constants and the most precise experiment :
GeV810)012.0835.1(exp)A(K 0
Difference between prediction and experiment : 3.8 %
Best experiment,
LEAR (CERN), 1992
ν)μBR(K)0ππBR(K
First step :
measurement of
at precision around (less ?) 1 %
Precision 1.5 %
![Page 4: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/4.jpg)
M. Martemianov, ITEP, October 2003
DST - version N 15 for kpm - stream
Run numbers : 23542-27133 (2387 DST - files)
All runs of 2002 year
Total statistics : 283.5 pb-1
Number of pions candidates : 1.649 106
Number of muons candidates : 4.919 106
Statistical estimation of result
Selected - window :
190 - 220 MeV/c
Selected - window :
220 - 260 MeV/c
- hyphotesis for
secondary particles
Statistical error on the level of 0.1 %
![Page 5: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/5.jpg)
M. Martemianov, ITEP, October 2003
cos.
exp,)
KK()
KKR(
00
KvetoKselKfit.Ktrigger
window
Ktrigger - trigger efficiency, extracted from EXP. data
Kfit - efficiency of signals and background rejection,
based on MC data and performed of EXP data,
Ksel - selection efficiency, from MC and EXP. data
Kvetocos - efficiency of cosmic veto rejection, EXP. data
Tag strategy
![Page 6: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/6.jpg)
M. Martemianov, ITEP, October 2003
0
Splitted tracks
“Wrong” orientation of tracks
At least one secondary kaon vertex with
40 cm < Rxy < 150 cm, |Z| < 210 cm
20 MeV/c < P sec < 320 MeV/c
Rejection of “Splitted” tracks
(events with |PK- P_sec| < 40 MeV/c . AND .
DF < 80 . OR . DF > 1720) , where
DF = | - | - acos (PK P sec)||
Secondary track selection
Kaon candidates from ECLO2
Only events with two kaons and Charge1 x Charge2 < 0
Selection by momenta in the first point in DC 40 < PK < 160
MeV/c
![Page 7: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/7.jpg)
M. Martemianov, ITEP, October 2003
Trigger efficiency / I
,
2
1
K
K+
Drift Chamber
K
K+
Auto - triggering for K+, based on EMC trigger
Trigger effciency = 100 %
Pion trigger (from K+ +0) based on the maximal number of clusters = 3, muon trigger (from K+ +) number of clustres = 1
+ - trigger :
Based on DC track information
Two tracks go to ECL
Rejection tracks fired same ENDCAP
![Page 8: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/8.jpg)
M. Martemianov, ITEP, October 2003
Trigger efficiency / II
Linear fit for both trigger (p0)
- auto - triggering : p0 = 0.3348 0.0008(stat.)
- auto - triggering : p0 = 0.3341 0.0007(stat.)
Trigger difference : 0.0007 0.0008 (trigger error = 0.2 % )
- tag, no auto-triggering : p0 = 0.3356 0.0004(stat.)
- auto - triggering : p0 = 0.3341 0.0008(stat.)
Trigger difference : 0.0014 0.0008 (trigger error = 0.4 % )
![Page 9: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/9.jpg)
M. Martemianov, ITEP, October 2003
0 - selection
Number of clusters > 2
No association to charged track
Ecl > 25 MeV
| t | < 3 ns
Search a minimum :
| (Ecl1 + Ecl2) - M(0) |
50 < M(0) < 210 MeV
space < 30 0, where space -
angle between 0 momenta from ECL
and calculated from DC
| Mfit(0) - M(0) | 0.7 MeV
space
![Page 10: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/10.jpg)
M. Martemianov, ITEP, October 2003
Selection of K decays
All selected events
Events with reconstructed as pions from K 0
Events selected as muons from K
Rejected clusters associated
to the neutral tracks
Minimum | (Ecl1 + Ecl2) -
M(0) | if 0 has common clusters
for both vertex
Procedure needs to get a clear signal for the both peak in windows
Good selection of - decay, small contamination of 0 - events survived
Selection didn’t change the shape of two peak’s shape
MC
![Page 11: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/11.jpg)
M. Martemianov, ITEP, October 2003
Four main modes in geanfi :K K e0K 0K 0 0
Three-body decays
ppexp1
p)(
21
03 xxf
Sum = 15.3 % 0 - selection doesn’t change shape of three - body decays
2 = 1.2
MC data
MC data
MC data + 0 - sel.
![Page 12: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/12.jpg)
M. Martemianov, ITEP, October 2003
Description of - peak
Exp. tails
Step N2 :
Experiment - extracting launch shape of peak for experimental data
Two contributions : and three - body background
Step N1 :
Pure MC - extracting launch shape of peak (3 Gaussians at the same mean value + 2 exponential functions due to effect of multiple scattering)
three-body backg.
- backg.
![Page 13: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/13.jpg)
M. Martemianov, ITEP, October 2003
Description of - peak
Step N1 :
Pure MC - extracting launch shape of peak (4 Gaussians, each 2 Gaussians have the same mean value + 2 exponential functions)
Exp. tails
Step N2 :
Experiment - extracting launch shape of peak for experimental data
One contribution : - background
-backg.
![Page 14: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/14.jpg)
M. Martemianov, ITEP, October 2003
Fit of two peaks
MCthreexfpxfpxfpxF
,)(
3)(
1)(
0)(
Fit gives a full description of all type of kaon decays in DC
f(x)three - extracted from MC
![Page 15: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/15.jpg)
M. Martemianov, ITEP, October 2003
Total statistics
Run Set Signal( -peak)
Signal( -peak)
Bothsignals
23542-24071 201469 600392 80186124072-24626 203407 608802 81220924627-25166 206973 618981 82595425167-25627 208149 620540 82868925628-26065 208810 622589 83139926068-26390 210602 626575 83717726391-26759 207853 618144 82599726761-27133 201755 603302 805057
Total value 1649018 4919325 6568343`
All data diveded on 5 sets
![Page 16: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/16.jpg)
M. Martemianov, ITEP, October 2003
Fit quality
Run Set Correctioncoefficient, %
2( -peak)
2( -peak)
2(both signals)
23542-24071 92.46 0.33 1.30 1.48 1.61
24072-24626 92.69 0.33 1.23 1.50 1.5824627-25166 92.26 0.33 1.32 1.29 1.6125167-25627 92.41 0.33 1.33 1.38 1.5125628-26065 92.55 0.33 1.34 1.48 1.6426068-26390 92.82 0.33 1.24 1.34 1.6026391-26759 92.68 0.33 1.41 1.38 1.6326761-27133 92.53 0.33 1.35 1.46 1.55
`
![Page 17: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/17.jpg)
M. Martemianov, ITEP, October 2003
Correction coefficient on background
Ratio as function of data set
Linear fit gives : 0.3352 0.0003(stat.)
Stat error : 0.09 %
Correction coeff. physical background
Linear fit gives :
Kfit = 0.9255 0.0012(fit.)
Fit error : 0.13 %
![Page 18: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/18.jpg)
M. Martemianov, ITEP, October 2003
Comparison data / MC
Fit can be checked by MC data using the same way :
KMC = 97.10 0.25 %
Kfit = 96.66 0.24 %
Ratio = 0.3174 0.0006
Ratio Kmc = (0.30863 0.00055)MC
Kfit = 0.9255 0.0012
Ratio = 0.3352 0.0003
Ratio Kfit = 0.3102 0.0012
MC : EXP :
On MC fit and real number of ratio coefficient are very close (difference = 0.44 0.35) (contribution to the syst. error)
Total MC correction coefficient : Ksel. = 1.080 0.002
![Page 19: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/19.jpg)
M. Martemianov, ITEP, October 2003
Selection efficiency / I
Ksel = decay vertex window
decay - correction on decay of charged pions vertex - selection of vertex for pions and muons window - correction of signals for all momentum range
decay - can be extracted on MC only using a convenient cut on the track length of secondary particles
vertex, window - estimated on MC and EXP, must be different in MC and EXP. Data due different momentum resolution
![Page 20: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/20.jpg)
M. Martemianov, ITEP, October 2003
Selection efficiency/ II
Distributions on MC and EXP are the same Cut for tracks length on all tracks (> 40 cm) gives
decay = 1.0443 0.0016 (stat.)
Calculation of decay
Main part of this value (1.036) can be calculated from PDG pion decay length, its mass and averaged laboratory momentum (205 MeV/c).
The rest can be attributed to pion decay at larger than 40 cm length with spoiled reconstraction of the pion track due to the presence of pion decay product.
![Page 21: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/21.jpg)
M. Martemianov, ITEP, October 2003
Selection efficiency/ IV
Exp. data
Correction for pions : 96.3 %
Correction for muons : 99.5 %
Correction coefficient for
windows by fit :
1.030 0.002(stat.) (0.2 %)
MC. data Correction for pions : 97.2 %
Correction for muons : 99.2 %
Correction coefficient for
windows by fit : 1.019 0.003
MC real coefficient :
1.020 0.003
Calculation of window
Based on fit parameters
Calculates the percentage muons and pions inside window
Different for MC and EXP data
![Page 22: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/22.jpg)
M. Martemianov, ITEP, October 2003
Selection efficiency/ V
Calculation of vertex
K
K+
+KK+
EMC - cluster
Two EMC clusters only for charged tracks, + - seleclted by momenta
Investigated vertex
vertex = vertex cuts
Investigated vertex
Two EMC clusters only for charged tracks, + - seleclted by momenta, two clusters from gammas
21
![Page 23: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/23.jpg)
M. Martemianov, ITEP, October 2003
Selection efficiency/ VI
Mean value of efficiency (sum by all kaons momenta gives vertex efficiency :
Pions : 86.79 0.18 %, Muons : 86.65 0.08 %
Difference : 0.14 0.20 % (contribution of stat error for vertex efficiency)
Selected muons
Selected pions
Efficiency of vertex efficiency for muons and pions as function of kaons momenta
![Page 24: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/24.jpg)
M. Martemianov, ITEP, October 2003
Selection efficiency/ VI
Calculation of cuts Calculated by MC and corrected by EXP
Includes cuts to reject splitted tracks and cuts on momenta of secondary tracks
MC : cuts = 1.0137 0.0016(stat)
Difference between MC and EXP based only on momenta cuts on high region (main contribution based on muons) and differnece equal to 0.5 %
EXP : cuts = 1.0086 0.0020(stat)
MC distribution of the secondary particles in the laboratory system for muons and pions
from K
from K 0
![Page 25: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/25.jpg)
M. Martemianov, ITEP, October 2003
Summary of selection efficiency
Type Correction coefficient(MC/ EXP)
Syst. error,%
Selection and pions decays 1.0443 0.16
Vertex selection 1.0137 1.0086 0.16 0.26
Kinematical window 1.020 1.0302 0.3 0.2
Total value 1.080 1.085 0.38 0.36
`
![Page 26: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/26.jpg)
M. Martemianov, ITEP, October 2003
Cosmic veto
S = N(vetocos=0) + N(vetocos=1,t3flag=0)+N(t3flag=1)
Kvetocos = 1+64N(t3flag=1) / S
Check cosmic veto for runs 26111-27133
Type of events vetocos = 0 vetocos =1 t3flag = 1 Kvetocos
+, 4.789106 4466 5564 1.00073 0.00010
+0, 0 0.621106 111 5 64 1.00051 0.00020
No difference between rejection of different type of event by cosmic veto on the level 210 4
![Page 27: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/27.jpg)
M. Martemianov, ITEP, October 2003
Corrections and erros
Type Correctioncoefficient
Syst. error,%
Source
Trigger 1.0 0.2 EXP
Background / fit 0.9255 0.46 EXP
Selection and pions decays 1.085 0.36 MC/EXP
Cosmic veto 1.0 0.2 EXP
K decay 0.994 Nucl. Phys.,B115, 55*
Total value MC/EXP 0.9981 0.65
`
*) Taken from previous experiments, we plan to recalculate the coefficient, but now use the same value to compare with pevious experiments.
![Page 28: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/28.jpg)
M. Martemianov, ITEP, October 2003
Comparison with world data
0.00220.00030.3346ν)μBR(K
)ππBR(K (syst.)(stat.)0
2(syst.)(stat.) 10)65.00.09(133.46
![Page 29: Analysis of ratio BR( K 0 )/BR(K )](https://reader036.fdocuments.us/reader036/viewer/2022062322/56814caf550346895db9b625/html5/thumbnails/29.jpg)
M. Martemianov, ITEP, October 2003
Conclusion
ν)μBR(K)ππBR(K 0
was measured
Result has a good agreement with world data
Statistical error is negligible due to the huge sample of kaon decays (more than 6.5 M).
Systematic error ( 0.65 %) dominates. It improves accuracy for the ratio by a factor of 2.7
In principal, result can be updated by further investigation of MC / EXP uncertanties and true calculation of K decay