Scalar Mesons in Phi Radiative Decay


Book Description

Existing predictions for the branching ratio for phi -> KK(sub)gamma ma phi -> S(sub)gamma (where S denotes one of the scalar mesons f(sub)0(975) and alpha(sub)0(980)) vary by several orders of magnitude. As a byproduct we find that the branching ratio for phi -> K^0K^0(sub)gamma is










CP Violation


Book Description




Time-Dependent CP Violation Measurements


Book Description

This thesis describes a high-quality, high-precision method for the data analysis of an interesting elementary particle reaction. The data was collected at the Japanese B-meson factory KEKB with the Belle detector, one of the most successful large-scale experiments worldwide. CP violation is a subtle quantum effect that makes the world look different when simultaneously left and right and matter and antimatter are exchanged. This being a prerequisite for our own world to have developed from the big bang, there are only a few experimental indications of such effects, and their detection requires very intricate techniques. The discovery of CP violation in B meson decays garnered Kobayashi and Maskawa, who had predicted these findings as early as 1973, the 2008 Nobel prize in physics. This thesis describes in great detail what are by far the best measurements of branching ratios and CP violation parameters in two special reactions with two charm mesons in the final state. It presents an in-depth but accessible overview of the theory, phenomenology, experimental setup, data collection, Monte Carlo simulations, (blind) statistical data analysis, and systematic uncertainty studies.




Study of CP Violation in Dalitz-Plot Analyses of B-Meson Decays to Three Kaons


Book Description

The Standard Model (SM) explains CP violation in terms of the CKM matrix. The BABAR experiment was designed mainly to test the CKM model in B decays. B decays that proceed through b → s loop diagrams, of which B → KKK decays are an example, are sensitive to new physics effects that could lead to deviations from the CKM predictions for CP violation. We present studies of CP violation in the decays B+ → K+K-K+, B+ → KS0KS0K+, and B0 → K+K-KS0, using a Dalitz plot amplitude analysis. These studies are based on approximately 470 million B$\bar{B}$ decays collected by BABAR at the PEP-II collider at SLAC. We perform measurements of time-dependent CP violation in B0 → K+K-KS0, including B0 → [Phi]KS0. We measure a CP-violating phase [beta]eff ([Phi]KS0) = 0.36 ± 0.11 ± 0.04 rad., in agreement with the SM. This is the world's most precise measurement of this quantity. We also measure direct CP asymmetries in all three decay modes, including the direct CP asymmetry ACP ([Phi]K+) = (12.8 ± 4.4 ± 1.3)%, which is 2.8 sigma away from zero. This measurement is in tension with the SM, which predicts an asymmetry of a few percent. We also study the resonant and nonresonant features in the B → KKK Dalitz plots. We find that the hypothetical scalar fX(1500) resonance, introduced by prior analyses to explain an unknown peak in the mKK spectrum, cannot adequately describe the data. We conclude instead that the fX(1500) can be explained as the sum of the f0(1500), f'2(1525), and f0(1710) resonances, removing the need for the hypothetical fX(1500). We also find that an exponential nonresonant model, used by previous analyses to describe the broad nonresonant feature seen in B → KKK decays, cannot fully model the data. We introduce a new nonresonant model that contains more free parameters, allows for phase motion, and contains both S-wave and P-wave components.