Mauro Donega’ - CDF collaboration meeting February 3, 2006

Bd,s->h1h2: BR, CP asymmetries,and lifetimes

S. Budroni, S. Donati, M. Donega’, S. Giagu,M. Morello, G. Punzi, D. Tonelli

CDF Collaboration Meeting February 3, 2006

Notes: 6175, 6356, 6357, 6453, 7066, 7978, 8057 (+linked notes on dE/dx calibrations and isolation studies)

Mauro Donega’ - CDF collaboration meeting February 3, 2006

Physics motivationsBd,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: Using Bd->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

Tree

Penguin

PHYSICAL REVIEW D 66, 054009 2002

Physics Letters B 4591999.306–320

Mauro Donega’ - CDF collaboration meeting February 3, 2006

Physics motivation (cont’d)

• Bs described as a two states system. • Evolution through Schroedinger equation:

off diagonal terms ->mixing M12, 12, = arg(- M12/12)

•What we measure: m = MH –ML ~ 2|M12| = L–H~ 2| 12 |cos()

•SM: ~0 -> CP eigenstates ~ mass eigenstates

•Bs-> is predicted to be 95% CP even => c(Bs->KK) ~1/ L

•Bs->KK lifetime combined with FS () can give .

•Measurement of Bs->KK lifetime can be strongly affected by new CP violating physics => sensitivity to New Physics

_

Mauro Donega’ - CDF collaboration meeting February 3, 2006

DATA

Fitter Kinematics+PID

Raw fractions

Fitter Kinematics+PID+Lifetimes

Acceptance corrections

LifetimesBR and ACP

Signal extraction

Optimized sample

Two groups:BR, ACP and Lifetimesworked on the same data sample:Ideal x-check of the

common results !

Mauro Donega’ - CDF collaboration meeting February 3, 2006

Data and MC samplesDataset: xbpp0d ~355 pb^-1 (BPAK good run list applied)Triggers:

B_PIPIB_PIPI_HIGH_PT (~7% of the total)

MonteCarlo: BMC framework 5.3.4Simulated the four signal modes:

Bd->K, Bd->, Bs->KK, Bs->K

Reconstruction:CharmMods – 5.3.4Track refit with L00Primary vtx from beamline

Mauro Donega’ - CDF collaboration meeting February 3, 2006

Signal extractionOptimization performed independently by the two groupsLead to similar set of cuts:

BR, ACP Lifetimes

Isolation > 0.525 > 0.5

Pt(trk1)+Pt(trk2) - > 5.95 (GeV/c)

D0(B) < 70 (um)

< 51 (um)

Min(|d0(trk1)|,|d0(trk2)|) - > 180 um

Lxy > 300 um

-

Prob(2 vtx 3D) - > 0.01

2 vtx 3D < 15 -

S/B~ 2

Mauro Donega’ - CDF collaboration meeting February 3, 2006

Background mass description

combinatorial

Bd/s/K

Include Bd/s/K in themass description (little bias to the lifetimes,included as systematic uncertainty)

Fit combinatorial bkg • Shape• fraction

Lifetimes

B->hh signalsto be disentangled

BR ACP

Mauro Donega’ - CDF collaboration meeting February 3, 2006

Disentangling the signal fractions

events

jbck

channels

i

ji FbFfibL )()1(

BPAK calibrations

),,,(),(),( 212121, ppzzIDppPmKINF bkgi

Bd+-

Bd K-+ Bd K+-

Bs K+K-

mass

mass

mass

mass

e

K

p

Momentum (GeV/c)

2

Mauro Donega’ - CDF collaboration meeting February 3, 2006

Extract the lifetimesMC based lifetime extraction (tested on B->Ddecays CDF7386)

=

Background described with a templateOn the right sideband (combinatorial only) =

Events after trigger+offline cuts

Lifetime MC ev/ev ct error

Mauro Donega’ - CDF collaboration meeting February 3, 2006

Raw fractions results

F(Bd K) 62.8

± 1.7 62.7

± 1.7

F( Bd+- ) 13.7

± 1.5 15.3

± 1.4

F(Bs KK) 22.2

± 1.7 22.3

± 1.6

F(Bs K) 1.3 ± 1.4 -0.3 ± 1.0

LifetimesBR, ACP

Compatible results !

Mauro Donega’ - CDF collaboration meeting February 3, 2006

BR ACP

=XXX ± 0.039 (stat) ± 0.013(syst)

Mauro Donega’ - CDF collaboration meeting February 3, 2006

ct (cm)

Lifetimes results

c(Bd)452 ± 24 460 ± 4

c(Bs KK) 463 ± 56 458 ± 53

CP/CP -0.08 ± 0.23

c(Bd)floating c(Bd) PDG constrained

z2

p1+p2

mass z1

In agreement with world average 460 ± 4 um

Mauro Donega’ - CDF collaboration meeting February 3, 2006

Systematic uncertainties

5.6 um

Lifetimes

0.013

BR ACP

Mauro Donega’ - CDF collaboration meeting February 3, 2006

Status (360 pb-1) and Plans (1 fb-1)

Status:• BR and ACP pre-blessed on January 26th, 2006• Lifetime measurement blessed on January 26th, 2006

Plans: • Bless BR and ACP 360 pb-1 and move to 1 fb-1

• Lifetimes move to 1 fb-1:Data skimming + MC production (in progress)dE/dx calibrations (~done)

Mauro Donega’ - CDF collaboration meeting February 3, 2006

Summary

The charmless two body B decay sample isExtremely Rich !

And leads to world class B physics measurements.

We are upgrading the BR and ACP measurements andfor the first time we measured the lifetimes on 360 pb-1:

c (Bd) = 452 ± 24 ± 6 umc (BsK+K-) = 458 ± 53 ± 6 um

(CP) / (CP) = -0.08 ± 0.23 ± 0.03