Radiative and electroweak penguin processes in exclusive B decays Dmytro Kovalskyi University of California, Santa Barbara BaBar Collaboration Dmytro Kovalskyi ICHEP 2006

Topics covered in this talk FCNC – a well known method to look for new physics bd and bd ll - new testing ground for Standard Model B B RUN1-5 – 316 fb-1 BK(*)l+l B l+l RUN1-4 – 209 fb-1 Dmytro Kovalskyi ICHEP 2006

Extraction of |Vtd/Vts| with B() decays Use SU(3) to relate B() to BK* Get |Vtd/Vts| with B() Form factor ratio 1/ = 1.17±0.09 hep-ph/0603232 Annihilation amplitude corrections R = 0.1±0.1 SU(3) breaking corrections: A.Ali, A.Parhomenko hep-ph/0105302 pre-ICHEP2006 results 2005 Belle observation of B() - first “direct” measurement of |Vtd/Vts| Dmytro Kovalskyi ICHEP 2006

Extracting signal in B() Reconstructed decays: B+, ++0 B0, 0 B, 0 Background Signal Major challenge – enormous background from Signal-background separation: 0 and  photon veto and photon isolation particle identification event shape event content kinematical constraints Maximum likelihood fit (E, mES, Neural Net, helicity) BD used to validate signal NN PDF BK* control sample and background ee - photon systematics Dmytro Kovalskyi ICHEP 2006

We do see B B++ B00 Dmytro Kovalskyi ICHEP 2006

BaBar estimate of |Vtd/Vts| Combined fit result: BR(B→(ρ/ω)γ)/BR(B→K*γ) Belle 2005 CDF measurement (mS) B-Factories average BaBar ICHEP 2006 CKM fitter code w/o Δms Global CKM fit excluding ms and B() Dmytro Kovalskyi ICHEP 2006

B l+l - Terra Incognita Standard Model prediction: Last measurement by Mark II (1990): Big Bang Expected improvement is ~ 104 – 105 |Vtd/Vts|2 suppressed with respect to BKll, which has been seen already Electroweak penguin and box amplitudes are not well constrained, so surprises are possible. Today Mark II Dmytro Kovalskyi ICHEP 2006

B l+l - no signal found with Standard Model just around the corner Dmytro Kovalskyi ICHEP 2006

Different ways to probe new physics in BK(*)l+l Electroweak penguins with substantial signal yield well established signal large number of observables to test SM branching fractions decay rate asymmetries angular distributions CP violation BK*ll (57 events) BKll (46 events) Dmytro Kovalskyi ICHEP 2006

Forward-backward asymmetry and K* polarization AFB – forward-backward asymmetry of the helicity angle of l+l- system FL – longitudinal component of polarization Theoretical curves Experimental results Dmytro Kovalskyi ICHEP 2006

Branching ratios, CP asymmetries Dmytro Kovalskyi ICHEP 2006

Conclusion BaBar confirms Belle observation of B(), finds first evidence for B++ and provides the most precise measurement of the decay rate: Based on this information we estimate: New search for B l+l improves the previous upper limit measured by Mark II by about 4 orders of magnitude: Significant signal yield in BK(*)l+l decays allows to measure the forward-backward asymmetry of l+l- system, which provide a way to probe for new physics contribution in radiative and electroweak penguin decays Dmytro Kovalskyi ICHEP 2006

BACK UP SLIDES Dmytro Kovalskyi ICHEP 2006

The CKM matrix Dmytro Kovalskyi ICHEP 2006

BaBar Detector e+ (3.1 GeV) e- (9 GeV) Electromagnetic Calorimeter Cerenkov Detector (DIRC) 1.5 T solenoid Electromagnetic Calorimeter Drift Chamber Instrumented Flux Return Silicon Vertex Tracker e+ (3.1 GeV) e- (9 GeV) Dmytro Kovalskyi ICHEP 2006

Improvements in background suppression  and  veto: mass resolution vs energy dependence and photon conversion (~10% less background) New Neural Net: B flight significance, B flavor tagging, correlations etc (~30% less background) Dmytro Kovalskyi ICHEP 2006

B/K l+l details Dmytro Kovalskyi ICHEP 2006