Working Group 12A

Angle Alpha and Direct CP Violation

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Theorist Conveners:
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David London (london@lps.umontreal.ca)
Amarjit Soni (soni@penguin.phy.bnl.gov)

Experimentalist Conveners:
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Marcello Giorgi (giorgi@axpia.pi.infn.it)
Hassan Jawahery (jawahery@umdhep.umd.edu)
Francois LeDiberder (diberder@frcpn11.in2p3.fr)

ORGANIZATION OF THE WORKING GROUP (SUB-GROUPS)

Measurement of the Angle Alpha

OUTLINE OF THE PHYSICS BOOK CHAPTER(text)

FIRST DRAFT OF THE PHYSICS BOOK CHAPTER (ps) 12-FEB-98

AGENDA FOR THE CALTECH MEETING (text)

AGENDA FOR THE ORSAY MEETING (text)

AGENDA FOR THE PRINCETON MEETING (text)

BRIEF SUMMARY OF ROME MEETING (postscript)

LIST OF INTERNAL WG12A DOCUMENTS AND MINUTES, ETC

Topics covered by the working group:

Measurement of the CKM unitarity angle Alpha

Measurement of Direct CP violation in charged B Decays

Measurement of CP violation purely in mixing

The goal of the working group is to explore experimental and theoretical issues in each of these three categories. On the experimental side we will perform analyses of simulated data on several benchmark modes. Our goal for the final product of this study which will be reported in the BaBar physics book at the end of the workshop is as follows:

Identify the decay modes which provide best sensitivity to the measurement of the angle alpha, for the study of direct CP in charged decays, and techniques for extracting CP violation in pure mixing.

Determine the dominant background effects and the expected detection efficiency for each mode.

Determine the expected statistical uncertainty in the measurement of the CP asymmetry for integrated luminosities of 10 fb-1, 30 fb-1 and 100 fb-1.

Identify sources of experimental systematic uncertainties and make an estimate of the size of these errors.

Identify sources of theoretical uncertainties and methods for estimating the sizes of these effect. In particular we need to examine various proposed methods for disentangling the penguin effects, such as the so-called isospin analysis.

On all these topics, and in particular item 1 and 4 we will need much input from our theorist colleagues, to help us formulate and answer relevant questions. A first order list of questions is as follows:

What are the range of branching ratios and asymmetries for the benchmark modes?

What are the range of the penguin effects for each mode?

How big the penguin contribution would have to be compared to the tree diagram for the penguin determination methods to give improved accuracy over a naive analysis?

The isospin analysis involving the extraction of the angle alpha from the 2pi, 3pi and 4pi modes:

What are the observables for the isospin analysis?

What are the constraints on the size of the penguin effect, namely the ratio of penguin to the tree diagram and the strong phases?

For the possible range of these parameters, how well can we isolate the penguin effects ? How does the uncertainty in the measurement of angle alpha depends on these parameters? How do we deal with ambiguities inherent in the isospin analysis?

Electroweak penguins: What are the constraints on the electroweak penguins? What measurements/analysis can be performed to isolate these effects?

CP Violation in the charged B modes:

What are the decay modes with measurable asymmetries?

What role can resonances play?

Is it possible to use (direct) CP asymmetries in charged B's to learn about CKM phases?

Can asymmetries in observables other than partial rates (PRA) be used?

Are there interesting multiparticle final states?

What can we learn about penguins from an SU(3) analysis? (overlap with WG3)

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This page is maintained by Hassan Jawahery (jawahery@umdhep.umd.edu)