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Setting Limits on Supersymmetry Using Simplified Models
Published on: November 16, 2013
Evidence for B(0) --> rho(0)rho(0) decays and implications for the Cabibbo-Kobayashi-Maskawa angle alpha
1Laboratoire de Physique des Particules, IN2P3/CNRS et Université de Savoie, F-74941 Annecy-Le-Vieux, France.
Physical Review Letters
|May 16, 2007
Summary
Researchers found evidence for the B0 --> rho(0)rho(0) decay, measuring its branching fraction and polarization. This research helps constrain the Cabibbo-Kobayashi-Maskawa angle alpha.
Area of Science:
- Particle Physics
- High-Energy Physics
- Quantum Chromodynamics
Background:
- Understanding B meson decays is crucial for testing the Standard Model of particle physics.
- The Cabibbo-Kobayashi-Maskawa (CKM) matrix describes quark mixing and CP violation.
- Penguin contributions to B decays can affect measurements of CKM parameters.
Purpose of the Study:
- To search for specific B0 meson decays: B0 --> rho(0)rho(0), B0 --> rho(0)f(0)(980), and B0 --> f(0)(980)f(0)(980).
- To measure the branching fraction and longitudinal polarization fraction for the B0 --> rho(0)rho(0) decay.
- To constrain the CKM unitarity angle alpha using measurements of B --> rho rho decays.
Main Methods:
- Analysis of approximately 384 million Upsilon(4S) --> BBbar decays collected by the BABAR detector.
- Utilizing data from the PEP-II asymmetric-energy e+e- collider.
- Statistical analysis to determine significance, branching fractions, and polarization, including systematic uncertainty evaluation.
Main Results:
- Evidence for the B0 --> rho(0)rho(0) decay with a 3.5 sigma significance.
- Measured branching fraction for B0 --> rho(0)rho(0) is (1.07 +/- 0.33 +/- 0.19) x 10^-6.
- Measured longitudinal polarization fraction f(L) for B0 --> rho(0)rho(0) is 0.87 +/- 0.13 +/- 0.04.
- Constrained the uncertainty on CKM angle alpha to 18 degrees at the 1 sigma level due to penguin contributions.
- Set upper limits on the branching fractions for B0 --> rho(0)f(0)(980) and B0 --> f(0)(980)f(0)(980) decays.
Conclusions:
- The observation of B0 --> rho(0)rho(0) provides valuable data for flavor physics.
- The measurements contribute to a more precise determination of the CKM angle alpha.
- Further studies can refine these measurements and explore other related B meson decays.
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