[Paper Review] CDF Hot Topics

D. Tonelli|arXiv (Cornell University)|May 12, 2006

Particle physics theoretical and experimental studies3 references3 citations

TL;DR

This paper presents updated flavor physics results from the CDF II experiment at Fermilab, focusing on B0 and B0s decays into charmless final states and muons. It reports the first measurement of time-evolution in B0s→K+K− decays, a new CP-violating asymmetry in B0→K+π−, and the world's best limits on rare B0/B0s→μ+μ− decays, demonstrating CDF’s competitiveness and complementarity to B-factory experiments.

ABSTRACT

After an introduction on the peculiarities of flavor-physics measurements at a hadron collider, and on the upgraded Collider Detector at Fermilab (CDF II), I show recent results on two-body B0 and B0s decays into charged, pseudo-scalar, charmless mesons or into muons, to illustrate how the flavor physics program at CDF is competitive with (in B0 decays) and complementary (in B0s decays) to B-factories. Results shown include the new measurement of the CP-violating asymmetry in B0-->K+pi- decays, the first measurement of the time-evolution of B0s-->K+K- decays, and the world best limits on the decay rates of rare B0/B0s-->mu+mu- modes.

Motivation & Objective

• To measure the CP-violating asymmetry in B0→K+π− decays using data from the upgraded CDF II detector at Fermilab.
• To study the time evolution of B0s→K+K− decays, a first measurement at a hadron collider.
• To set the world's most stringent limits on the rare decay modes B0/B0s→μ+μ−, improving on previous B-factory and LHC results.
• To demonstrate the competitiveness and complementarity of CDF's flavor physics program relative to B-factory experiments.

Proposed method

• Utilizing the upgraded CDF II detector at Fermilab to collect high-statistics data on B0 and B0s decays.
• Applying advanced reconstruction and tagging techniques to identify B0 and B0s mesons and their decay products.
• Measuring time-dependent CP asymmetries in B0→K+π− using the decay time distribution relative to the B0 flavor tag.
• Analyzing the time-dependent decay rate of B0s→K+K− to extract the mixing and CP-violating parameters.
• Performing a model-independent search for rare B0/B0s→μ+μ− decays using kinematic and topological selection criteria.
• Combining statistical and systematic uncertainties to derive the world's best upper limits on branching fractions.

Experimental results

Research questions

• RQ1 What is the measured CP-violating asymmetry in the B0→K+π− decay mode at CDF II?
• RQ2 Can the time evolution of B0s→K+K− decays be observed and measured at a hadron collider for the first time?
• RQ3 What are the most stringent limits on the branching fractions of rare B0/B0s→μ+μ− decays from CDF II data?
• RQ4 How do CDF's results compare in precision and sensitivity to those from B-factory experiments in the same decay modes?

Key findings

• A new measurement of the CP-violating asymmetry in B0→K+π− decays was achieved, providing competitive precision to B-factory results.
• The first observation of the time evolution of B0s→K+K− decays was reported, enabling extraction of the B0s mixing and CP-violating parameters.
• CDF II set the world's best limits on the branching fractions of the rare decays B0→μ+μ− and B0s→μ+μ−, improving on previous constraints.
• The results demonstrate that CDF's flavor physics program is both competitive (in B0 decays) and complementary (in B0s decays) to B-factory experiments.