projektbericht belle vorstandssitzung 8. juni 2006 kek, projektbericht belle rekordluminosität svd...

Projektbericht BELLE Vorstandssitzung 8. Juni 2006

KEK 　高エネルギ ,

Projektbericht BELLE

• Rekordluminosität

• SVD Upgrade bei BELLE

• Neue wichtige Resultate

Collaboration

• HEPHY Physik-Analysen


Lpeak=1.62 × 1034cm-2sec-1

design=1034cm-2sec

KEKB Collider

e-

8GeV

e+

3.5GeV

= 0.425

B-Factory(on the 4s resonance)

B-Factory(on the 4s resonance)

BBthreshold


BELLE-DetectorBELLE-Detector

CDC

KLM

ECL

SVD


Ikado et al hep-ex/0604018

Signal

One B (tag) fully reconstructed

Remaining energyof signal B in ECL

•Pure leptonic decay

2.05+0.65-0.55(stat)

4.0


0.245

10.75


Addresses the same physics issue as Bs- Bs mixing _

signal

qq

K*other B

Mohapatra. Nakao, Nishida et al hep-ex/0506079

CDF

CDF

First Observation of bd


Additional Constraints for Unitary Triangle


Current status

CPV angles only:η=0.321±0.027=0.193±0.57

sides only:η=0.342±0.0

2 =0.216±0.06

Constraints from “Loop” Constraints from tree


HEPHY Physik-Analysen

Christoph Schwanda: B l B l B l Vub

Laurenz Widhalm: Formfaktoren semileptonischer D° Zerfälle

Franz Mandl+G.L+H.D:BRs der inklusive Zerfälle D° KK () X Gerhard Leder + L.W.: BRs der inklusive Zerfälle Ds Gerald Richter: Dekohärenz Modelle verschränkter B-Paare Winfried Mitaroff: Y(5S)Bs

(*)Bs(*)[D0K0

s]


Ktag

D

mass-constrained vertex fits

e+ e-3.5 GeV 8 GeV

K

K

D0

slow

e/µ

D*-

„inverse“ fit

tag side

Method of Reconstruction (Event Topology)

D*

signal side

additional primary mesonsIP

note:• all possible combinations tried in parallel• cuts after complete reconstruction• equal weight for remaining combinations no event loss due to particle exchanges!

•Semileptonic Formfactors


Summary of Signal / Background Decomposition

Results (282 fb-1 of BELLE data) Ke K e

signal events 1318

± 37stat ± 7syst

1249

± 37stat ± 25syst

126

± 12stat ± 3syst

106± 12stat ± 6syst

fake D0 bkg 12.6 ± 2.2 12.2 ± 4.8 12.3 ± 2.2 12.5 ± 4.5

semileptonic bkg* 6.7 ± 2.6 10.0 ± 2.5 11.7 ± 1.2 12.6 ± 1.9

hadronic bkg** 11.9 ± 5.6 62.1 ± 23.9 1.8 ± 0.7 9.7 ± 3.7

fake-D0 bkg

Kl bkg

D0 eD0 e

D0 D0

l bkg

D0 eD0 e

D0 D0 hadronic bkg

m² / GeV²

•*error dominated by MC statistics • ** error dominated by fit errors & bias special bkgsample

MC

data

data

data

data

remaining signal


Absolute Branching Ratios

BRs (%) this analysis PDG(2005)

CLEO-c (hep-ex/0505035)

K-e+ 3.45 ± 0.10stat ± 0.19syst 3.62 ± 0.16 3.44 ± 0.10stat ± 0.10syst

K-+ 3.45 ± 0.10stat ± 0.21syst 3.20 ± 0.17

-e+ 0.279 ± 0.027stat ± 0.016syst 0.311 ± 0.030 0.262 ± 0.025stat ± 0.008syst

-+ 0.231 ± 0.026stat ± 0.019syst 0.24 ± 0.04

• ratio to total number of recoil D0 tags

• efficiency correction • corrected for bias due to differences data/MC

(1.9%±3.9%)


Form Factors – Comparison with Models

ISGW2 modellattice calculation modified pole model

D0 lD0 l

D0 lD0 l

pole mass (GeV)

Kl 1.82 ± 0.04stat ± 0.03syst

l 1.97 ± 0.08stat ± 0.04syst

simple pole

Kl 0.52 ± 0.08stat ± 0.06syst

l 0.10 ± 0.21stat ± 0.10syst

modified pole(poles fixed at theo. values)

fit results

f+(0)

Kl 0.695 ± 0.007stat ± 0.022syst

l 0.624 ± 0.020stat ± 0.030syst

preprint hep-ex/0604049, submitted to PRL


D0(K+K-) XData Generic MC

K0K0

D0 D0

K+K-

X

•D0 - BranchingRatios


Mass window = 255- 141(side-extr)=114

D0(K+K-) X

Mass window D0: 1.84<M(D0)<1.89

Mass window : 1.00<M()<1.04

Mass window D0= 332-80(sideband)=252 Mass window D0=191-25(sideband)=166

Mass window =458-182(sideband-extr) =276

Generic MCData

BG?=4*35

Correct BGshape from MC ?

D0

D0

0.37%+/-0.04

1.02%+/-0.141.71% +/- 0.76

0.39%+/-0.012

•PDG

Projektbericht BELLE Vorstandssitzung 8. Juni 2006 drydiff

gen MC m(K+K-) RS-WS comparison with data (*), scalefactor 0.445

green D0 X

pink not from D0

blue D0 K+K-XX

yellow no D0

red no K+(K-)

Projektbericht BELLE Vorstandssitzung 8. Juni 2006 fitdat

DATA FIT m(K+K-) 3 Gaussians + Polyn. 4th order

Projektbericht BELLE Vorstandssitzung 8. Juni 2006 Missing Mass for D0 X

Data

Mass window : 1.00<M()<1.04

Generic MC

K0 K0


Ktag

D

mass-constrained vertex fits

e+ e-3.5 GeV 8 GeV

K+

Ds-

µ

Ds*-

„inverse“ fit

tag side

Method of Reconstruction (Event Topology)

signal side

additional primary pionsIP

...•Ds inclusiveExample Ds XPDG:(18+/-10)%or exclusive:(semi)leptonicDs BaBar(0.65+/-0.08)%Ds(6.4+/-1.5)%Ds l (2.0+/-0.5)%

Ds

Signal


•Ds


New: Ds → and fDs

2

2

222

22

18

)(

s

ss

D

lDlD

csFls m

mmmf

VGlD

sDf

BaBar

sD

c

s

W

Helicity-suppressed leptonic decay:

• directly related to decay constant fDs

• feeds interpretation of B, Bs mixing

Analysis Method: “D reco” in e+e- → cc

Single best measurement of decay constant!

ss DD*

*

0

D

D

D

D

s

D reco side

Signal peak in ss DD

MMM *

310)9.03.08.05.6()( sDMeV)19617279( syststat

ss DDf

BaBar (230fb-1):

Lattice QCD:

MeV)17249( sD

f

(normalize to Ds → )


Best Candidate Selection

• signal yield can be increased by a „best candidate selection“ in case of ambiguities, e.g. by choosing maximal „slow“ gamma momentum• improvement: ~40%• important: no bias on background!• a cut on the Ds fit (not done in the plots) further increases the yield

Ds invariant mass Ds invariant mass

signal / no ambiguitysignal / several associationssignal / lost because wrong candidate selectedbackground

no best candidate selection largest “slow” gamma energy taken


DATA (ca. 3.2% of available statistics)

Ds invariant mass

Fit: 705 events ca. 22000 Ds expected in total

• first look into data (only 3.2% of available data)• simple fit gaussian + linear curve for rough estimate

•hope: reconstruction of muon and neutrino of Ds or Ds will further reduce ambiguity enhancement of signal• cuts are still under development•Ds needs suppression of remaining energy in ECL, similar toB analysis

• Room for improvement• also best candidate selection might be further improved•Cross-check with hadronic channels, i.e Ds


The decay

• βγcτB0

= 196 μm(LAB)

R t expt 2GCORE

CORE

2

expt 2GTAIL

TAIL

2

exp t 2GCOREk

● Δm = 0.489 1012 ћs-1 = 0.754 τ

B0-1

beam axis3.5 GeV e+8 GeV e-

interaction point(IP) =

primary vertex(PV) decay point 2

= secondary vertex

entanglement region

l-

decay point 1 =

secondary vertex

l+

K0s π-

π +

μ+

typical Υ(4S)

resonance decay

z0 , t

0

z1 , t

1

z2 , t

2

t

B0

B0

θ

B0 B0

Gerald Richter


Adapted response function model

R t expt 2GCORE

CORE

2

expt 2GTAIL

TAIL

2

exp t 2GCOREk

sum of 2 gaussians +back to back neg. exponential

“gaussian pagoda”resolution function R(t)

shown for t1 parametergood accordance of fit

function up to +/- 4 mm


applied cuts to get fit working

lower tailcut

● varied the symmetric quantile cuts, to find point, where the ML fit is not disturbed by tails.

● with lower = upper percentage of histogram entries within the ± 40 τ

B0 window removed

● t1: 0, 1, 2, 4 %● dt: 0, 1, 2 %

upper tailcut


• for 2 cases of fixed dt quantile cuts 1%, 2%

• behaviour of the ML fit result for a given

λTRUE

= 0

• with increasing cut percentage, λ

FIT pulled

towards 0

• cutting too much will impair error model correctness

• 2% for both parameters looks like a good choice.

fit results on signal BELLE-MC with varied quantile cuts fit works

BELLE-MC with different in preparation

Projektbericht BELLE Vorstandssitzung 8. Juni 2006 SVD 2.5


Generated number of events (~May 22)k events

18Mevents per 20 days870 days for seed0-2Need your help!

•Generic MC-Production for BELLE-Collaboration

•VIENNA

•Service Jobs

projektbericht belle vorstandssitzung 8. juni 2006 kek, projektbericht belle rekordluminosität svd...

Documents

observation of b d slide

signal slide

fake d

b s b s mixing

pole model d

d0d0 slow e d

tree slide

prl slide