222 research outputs found
Extracting Weak Phase Information from B -> V_1 V_2 Decays
We describe a new method for extracting weak, CP-violating phase information,
with no hadronic uncertainties, from an angular analysis of B -> V_1 V_2
decays, where V_1 and V_2 are vector mesons. The quantity can be cleanly obtained from the study of decays such as B_d^0(t) ->
D^{*\pm} \rho^\mp, D^{*\pm} a_1^{\mp}, D^{*0} K^{*0}, etc. Similarly, one can
use B_s^0(t) -> D_s^{*\pm} K^{*\mp} to extract . There are no
penguin contributions to these decays. It is possible that will be the second function of CP phases, after , to be
measured at B-factories.Comment: 4 pages, RevTeX, no figure
Heavy Baryon Production and Decay
The branching ratio B(Lambda_c -> p K- pi+) normalizes the production and
decay of charmed and bottom baryons. At present, this crucial branching ratio
is extracted dominantly from B.bar -> baryons analyses. This note questions
several of the underlying assumptions and predicts sizable B.bar -> D(*) N
N'.bar X transitions, which were traditionally neglected. It predicts
B(Lambda_c -> p K- pi+) to be significantly larger (0.07 +/- 0.02) than the
world average. Some consequences are briefly mentioned. Several techniques to
measure B(Lambda_c -> p K- pi+) are outlined with existing or soon available
data samples. By equating two recent CLEO results, an appendix obtains B(D0 ->
K- pi+)= 0.035 +/- 0.002, which is somewhat smaller than the current world
average.Comment: 27 pages, 4 eps figures, revte
Can One Measure the Weak Phase of a Penguin Diagram?
The b -> d penguin amplitude receives contributions from internal u, c and
t-quarks. We show that it is impossible to measure the weak phase of any of
these penguin contributions without theoretical input. However, it is possible
to obtain the weak phase if one makes a single assumption involving the
hadronic parameters. With such an assumption, one can test for the presence of
new physics in the b -> d flavour-changing neutral current by comparing the
weak phase of B_d^0-{\bar B}_d^0 mixing with that of the t-quark contribution
to the b -> d penguin.Comment: 20 pages, no figure
Determining the Quark Mixing Matrix From CP-Violating Asymmetries
If the Standard Model explanation of CP violation is correct, then
measurements of CP-violating asymmetries in meson decays can in principle
determine the entire quark mixing matrix.Comment: 8 pages (plain TeX), 1 figure (postscript file appended), DAPNIA/SPP
94-06, NSF-PT-94-2, UdeM-LPN-TH-94-18
Exploring CP Violation with B_d -> D K_s Decays
We (re)examine CP violation in the decays B_d -> D K_s, where D represents
D^0, D(bar), or one of their excited states. The quantity can be extracted from the time-dependent rates for and , where the decays to
. If one considers a non-CP-eigenstate hadronic final state to
which both D(bar) and D^0 can decay (e.g. ), then one can obtain two
of the angles of the unitarity triangle from measurements of the time-dependent
rates for and .
There are no penguin contributions to these decays, so all measurements are
theoretically clean.Comment: 15 pages, LaTeX, no figure
CP violation and CKM phases from angular distributions for decays into admixtures of CP eigenstates
We investigate the time-evolutions of angular distributions for decays
into final states that are admixtures of CP-even and CP-odd configurations. A
sizable lifetime difference between the mass eigenstates allows a probe
of CP violation in time-dependent untagged angular distributions. Interference
effects between different final state configurations of , determine the Wolfenstein parameter from
untagged data samples, or -- if one uses as an additional
input -- the notoriously difficult to measure CKM angle . Another
determination of is possible by using isospin symmetry of strong
interactions to relate untagged data samples of
and . We note that the untagged angular
distribution for provides interesting information about
electroweak penguins.Comment: 19 pages, LaTeX, no figure
B-Decay CP Asymmetries, Discrete Ambiguities and New Physics
The first measurements of CP violation in the system will likely probe
, and . Assuming that the CP angles
, and are the interior angles of the unitarity
triangle, these measurements determine the angle set
except for a twofold discrete ambiguity. If one allows for the possibility of
new physics, the presence of this discrete ambiguity can make its discovery
difficult: if only one of the two candidate solutions is consistent with
constraints from other measurements in the and systems, one is not sure
whether new physics is present or not. We review the methods used to resolve
the discrete ambiguity and show that, even in the presence of new physics, they
can usually be used to uncover this new physics. There are some exceptions,
which we describe in detail. We systematically scan the parameter space and
present examples of values of and the new-physics
parameters which correspond to all possibilities. Finally, we show that if one
relaxes the assumption that the bag parameters \BBd and \BK are positive,
one can no longer definitively establish the presence of new physics.Comment: 29 pages, LaTeX, 1 figures, presentation substantially reworked,
physics conclusions unchanged. This version will be published in Phys. Rev.
Method for Flavor Tagging in Neutral B Meson Decays
A method is proposed for tagging the flavor of neutral mesons in the
study of CP-violating decay asymmetries. The method makes use of a possible
difference in interactions in or systems with isospins 1/2
and 3/2, and would be particularly clean if the systems can be
detected as ``'' resonances.Comment: Submitted to Phys. Rev. D. 11 pages, LaTeX, Technion-PH-92-40 / PITHA
92/39 / EFI 92-5
In Pursuit of New Physics with B_s Decays
The presence of a sizeable CP-violating phase in B_s^0-B_s^0-bar mixing would
be an unambiguous signal of physics beyond the Standard Model. We analyse
various possibilities to detect such a new phase considering both tagged and
untagged decays. The effects of a sizeable width difference Delta Gamma between
the B_s mass eigenstates, on which the untagged analyses rely, are included in
all formulae. A novel method to find this phase from simple measurements of
lifetimes and branching ratios in untagged decays is proposed. This method does
not involve two-exponential fits, which require much larger statistics. For the
tagged decays, an outstanding role is played by the observables of the
time-dependent angular distribution of the B_s -> J/psi [-> l^+ l^-] \phi [->
K^+K^-] decay products. We list the formulae needed for the angular analysis in
the presence of both a new CP-violating phase and a sizeable Delta Gamma, and
propose methods to remove a remaining discrete ambiguity in the new phase. This
phase can therefore be determined in an unambiguous way.Comment: minor changes, lattice prediction of Delta Gamma updated, appears in
PR
Determination of the angle gamma using B -> D* V modes
We propose a method to determine the angle , using the
() modes. The is considered to decay to .
An interference of the and amplitudes is
achieved by looking at a common final state , in the subsequent decays of
. A detailed analysis of the angular distribution, allows
determination, not only of and , but also all the hadronic
amplitudes and strong phases involved. No prior knowledge of doubly Cabibbo
suppressed branching ratios of are required. Large CP violating asymmetries
( for ) are possible if is doubly
Cabbibo suppressed, while is Cabbibo allowed, for decays of
or .Comment: 12 Pages Revte
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