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B s  K + K - lifetime measurement and DG CP / G CP extraction. Mauro Donega DPNC Universite de Geneve Swiss Physical Society annual meeting 13 February 2006. B 0  hh’: Physics motivation. B d,s ->h 1 h 2 = Bd->k  , Bd->  , Bs->KK , Bs->K 

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b s k k lifetime measurement and dg cp g cp extraction
Mauro Donega BsK+K- lifetime measurement and DGCP/GCP extraction

Mauro Donega

DPNC Universite de Geneve

Swiss Physical Society annual meeting

13 February 2006

b 0 hh physics motivation
Mauro Donega B0hh’: Physics motivation
  • Bd,s->h1h2= Bd->k, Bd-> ,Bs->KK , Bs->K
  • Accessible to B factories: Bd->k, Bd-> 
  • Only at TeVatron (until >2007): Bs->KK , Bs-> K
  • Possible measurements:
  • Today:
    • direct CP asymmetry in Bd->k, Bs-> K
    • (counting experiment)
  • Future:
    • CP asymmetry in mixing Bd-> ,Bs->KK
  • (requires time dependent analysis)
  • Short term goal: UsingBd->k,Bd-> BR, constrain the relevant hadronic penguin parameters.
  • Long term goal: combine time-dependent Bd->  and Bs->KK
  • asymmetries (+other external input) to measure g

Tree

Penguin

PHYSICAL REVIEW D 66, 054009 2002

Physics Letters B 4591999.306–320

b 0 hh physics motivation1
Mauro Donega B0hh’: Physics motivation
  • Bs described as a two states system.
  • Evolution through Schroedinger equation:
  • off diagonal terms ->mixing
  • M12, G12, f = arg(- M12/G12)
  • What we measure:
  • Dm = MH –ML ~ 2|M12| DG = GL–GH~ 2| G12 |cos(f)
  • SM: f ~0 -> CP eigenstates ~ mass eigenstates
  • Bs-> is predicted to be 95% CP even => ct(Bs->KK) ~1/ GL
  • Bs->KK lifetime combined with FS (t) can give DG.
  • Measurement of Bs->KK lifetime can be strongly affected by
  • new CP violating physics => sensitivity to New Physics

_

slide4
Mauro Donega CDF

B =1.4 T

TIME OF FLIGHT

TOF: ~100ps resolution, 2sigmaK/ separation for tracks below 1.6 GeV/c

(significant improvement of Bs flavor tag effectiveness)

COT: large radius (1.4 m) Drift C.

  • 96 layers, 200ns drift time
  • Precise PT above 400 MeV/c
  • Precise 3D tracking in ||<1

(1/PT) ~ 0.1%GeV –1; (hit)~150m

  • dE/dx info provides >1.4 sigma K/ separation above 2 GeV
  • SVX-II + ISL: 5 + 1 (2) layers of double-side silicon (3cm < R < 30cm)
  • Standalone 3D tracking up to ||= 2
  • Very good I.P. resolution: ~30m (~20 m with Layer00)

LAYER 00:1 layer of radiation-hard silicon at very small radius

(1.5 cm) - expected 50 fs proper time resolution inBs Dsp

fully hadronic decays @ cdf
Mauro Donega

Secondary

Vertex

B

Decay Length

35m  33m = 47 m

(resolution beam)

Lxy

Primary

Vertex

d = impact parameter

Fully hadronic decays @ CDF

Silicon Vertex Tracker

Proper time distribution

TOY

Pt(trk) >2 GeV/c

Pt >5.5 GeV/c

100 m

|| <1

SVT selection

Detector smearing

Decay

data sample
Mauro Donega Data sample

L = 360 pb-1

Bdk

Bskk

Overlapped

Use PID to disentangle them

Bd 

MC

Bs k

Bs

Bd

signal fraction separation
Mauro Donega

Bdp+p-

mass

BdK-p+

Bd K+p-

mass

mass

BsK+K-

mass

Signal fraction separation

e

K

p

Momentum

(GeV/c)

2 GeV/c

lifetime extraction
Mauro Donega Lifetime extraction

MC based lifetime extraction (tested on B->Dp decays)

Events after trigger+offline cuts

=

Lifetime MC

ev/ev ct error

Background described with a template

On the right sideband (combinatorial only) =

results
Mauro Donega Results

Fractions

Lifetimes

summary
Mauro Donega Summary

We presented the first measurement of the Bd and Bs in two body charmless decays:

ct(Bd) = 452 ± 24(stat) ± 6(syst) mm ct(BsK+K-) = 458 ± 53(stat) ± 6(syst) mm

ct(Bd) = 1.51 ± 0.08(stat) ± 0.02(syst) ps ct(BsK+K-) = 1.53 ± 0.18(stat) ± 0.02(syst) ps

Using the HFAG 05 data ct(FS) = 441 ± 13 mm

DGCP/GCP = -0.08 ± 0.23 (stat) ± 0.03(syst)

other dg cp g cp measurements
Mauro Donega Other DGCP/GCP measurements

Theory prediction = 0.07 ± 0.02

hep-ph 0308029

CDF BsJ/ψΦ = 0.65 ± 0.01

Phys.Rev.Lett.94:101803,2005

This measurement = -0.08 ± 0.23 ± 0.03

HFAG average as of Winter 2005 = 0.31

http://www.slac.stanford.edu/xorg/hfag/results/index.html

+0.25

-0.33

+0.10

- 0.11

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