First evidence of
B0s→π+π- decays.
Primary authors: M.J. Morello, G. Punzi, F. Ruffini
This webpage collects the links to the CDF public note and to the
relevant supporting plots for the measurement of the branching
fractions of the B0s →π+π-
and B0 →K+K- decays.
These preliminary results were approved on May 19th,2011
by the CDF collaboration.
Motivations
Most effective models used in predictions of non-leptonic B meson decay amplitudes rely on perturbative expansions in the inverse of the b quark mass.
These provide accurate results for decays dominated by tree-level amplitudes, but suffer from significant uncertainties when penguin amplitudes or other sources
of large strong phases intervene. These uncertainties frequently limit the accuracy and predictivity of tests of CKM dynamics using these decays.
One of the largest sources of uncertainty is the size of penguin-annihilation topologies. These are processes where the two quarks composing the B meson annihilate
yielding a final state made of completely different quarks. Their amplitudes are difficult to calculate and experimental input is crucial to constrain their
magnitude. The B0s→π+π- mode proceeds only through annihilation amplitudes and a measurement of its
branching ratio would gauge the size of annihilation topologies improving the precision of predictions of a vaste class of hadronic B decays.
Its features are similar to the as yet unobserved B0→K+K- mode, but it has
a larger predicted branching fraction; a measurement of both modes would provide an even more accurate determination of
the strength of penguin-annihilation.
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Data and analysis
The data have been collected by the hadronic B trigger designed to select events containing track pairs exiting from a common
displaced vertex and correspond to about 6 fb-1 of integrated luminosity. This is an improvement of the measurement performed
on 1 fb-1 ( public web page
and CDF Public note 8579 ) published
on Phys. Rev. Lett. 103, 031801 (2009) and
Phys. Rev. Lett. 106, 181802 (2011) .
A complete description of the analysis is available here: CDF Public note 10498.
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We report the first evidence of the B0s→π+π- with a significance of 3.7σ,
including statistical and systematic uncertainties. No firm evidence for the B0→K+K- is found but the measured rate excludes zero at the 90% C.L."
We measured:
Using the (PDG 2010) input we obtained:
We set a 90% C.L. interval for the B0→K+K-.
Both modes are annhilation dominated decays.
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- Table: selection pdf
- Table: raw fit results pdf
- Table: systematic uncertainties on relative branching fractions pdf
- Table: systematic uncertainties on raw yields pdf
- Qualitative Mass only fit eps
- Fit projection onto invariant pipi-mass eps log
- Fit projection onto invariant pipi-mass square eps log
- Fit projection onto beta eps
- Fit projection onto p_tot eps
- Fit projection onto k+ eps
- Fit projection onto k- eps
- Fit projection onto k+ + k- eps
- Fit projection onto k+ - k- eps
- Fit projection onto beta (signal mass region [5.17, 5.33] GeV/c2) eps
- Fit projection onto p_tot (signal mass region [5.17, 5.33] GeV/c2) eps
- Fit projection onto k+ (signal mass region [5.17, 5.33] GeV/c2) eps
- Fit projection onto k- (signal mass region [5.17, 5.33] GeV/c2) eps
- Fit projection onto k+ + k- (signal mass region [5.17, 5.33] GeV/c2) eps
- Fit projection onto k+ - k- (signal mass region [5.17, 5.33] GeV/c2) eps
- Relative Likelihood plot for B0->KK eps log
- Relative Likelihood plot for B0s->pipi eps log
- -2 Delta Log(L) plot for B0->KK eps log
- -2 Delta Log(L) plot for B0s->pipi eps log
- Mass template (correct mass assignment) for B0->pipi eps log
- Mass template (correct mass assignment) for B0->Kpi eps log
- Mass template (correct mass assignment) for B0->KK eps log
- Mass template (correct mass assignment) for B0s->pipi eps log
- Mass template (correct mass assignment) for B0s->Kpi eps log
- Mass template (correct mass assignment) for B0s->KK eps log
- Mass template (correct mass assignment) for Lb->ppi eps log
- Mass template (correct mass assignment) for Lb->pK eps log
- pipi-mass square vs beta (Monte Carlo) for B0->hh eps
- pipi-mass square vs beta (Monte Carlo) for B0s->hh eps
- pipi-mass square vs beta (Monte Carlo) for Lb->ph eps
- pipi-mass square vs beta (Monte Carlo) for B0->pipi eps
- pipi-mass square vs beta (Monte Carlo) for B0->Kpi eps
- pipi-mass square vs beta (Monte Carlo) for antiB0->Kpi eps
- pipi-mass square vs beta (Monte Carlo) for B0->KK eps
- pipi-mass square vs beta (Monte Carlo) for B0s->pipi eps
- pipi-mass square vs beta (Monte Carlo) for B0s->Kpi eps
- pipi-mass square vs beta (Monte Carlo) for antiB0s->Kpi eps
- pipi-mass square vs beta (Monte Carlo) for B0s->KK eps
- pipi-mass square vs beta (Monte Carlo) for Lb->ppi eps
- pipi-mass square vs beta (Monte Carlo) for antiLb->ppi eps
- pipi-mass square vs beta (Monte Carlo) for Lb->pK eps
- pipi-mass square vs beta (Monte Carlo) for antiLb->pK eps
- Template of p_tot vs beta (Monte Carlo) for B0->pipi eps lego
- ......
- Universal Curves for positive particles eps
- Universal Curves for negative particles eps
- dE/dx residual in pion hypothesis for postive pions and kaons eps
- dE/dx residual in pion hypothesis for negative pions and kaons eps
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