479 research outputs found

### On a clean determination of $\phi_2$

We point out that time dependent study of four decay modes B^0(t)\to \Dbar
K_S, $B^0(t)\to D K_S$ \Bbar^0(t)\to \Dbar K_S, and \Bbar^0(t)\to D K_S
allows us to measure $\sin(\phi_1-\phi_2)$ - contrary to previously obtained
result that it measures $\sin(2\phi_1+\phi_3)$. The time dependent study of
$B_s^0(t)\to D^\pm_sK^\mp$, and the study of B^-\to K^-(D,\Dbar)\to K^-f
decay where $D\to f$ is a doubly Cabibbo suppressed decay yield information on
$\phi_3$, as previusly expected.Comment: 6 pages 2 figure

### Summary of Weak Decays, CKM and CP Violation Session Penguins

In our subgroup, we focused on penguin physics from various different angles.
Our discussions included: (1) A method to extract one of the angles of the
unitarity triangle $\phi_2$; (2) Methods to extract $\phi_3$ from $B\to K\pi$
decays; (3) Effects of non-minimal SUSY on B and K decays; (4) Understnding
large branching ratios for $B\to \eta'+K(K^*)$ decays; (5) New calculation for
hadronic matrix elements which are needed to compute $\epsilon'/\epsilon$.Comment: To appear in the proceedings for WIN99 Cape Tow

### Comments on CPT tests

What do we know about CPT symmetry? We conclude that the direcrt measurement
of CPT violation leads to a result that CPT violation force is limited to about
30% of CP violating forces. The best test of CPT symmetry is to see if
theoretical prediction for the phase of eta_{+-} and eta_{00} agree with
experiments. We discuss uncertainties associated with this prediction, and how
to improve it. A new test of CPT is also discussed.Comment: Talk presented at KEK-Tanash workshop on K decay

### Is Super-$B$ Sufficiently Superb? -- On the Motivation for a Super-$B$ Factory

Despite the great success of the $\Upsilon (4S)$ $B$ factories at KEK and
SLAC and the guaranteed addition of high sensitivity measurements on beauty
decays to be performed at the Tevatron and LHC, a strong case can be made for
an $e^+e^-$ Super-$B$ factory yielding data samples of order $10^{10}$ $B \bar
B$ pairs as a necessity rather than luxury. It has to be justified through its
ability to not only establish deviations from the Standard Model, but also
diagnose and interpret those in terms of specific features of the New Dynamics.
The role to be played by a Super-$B$ factory is thus analogous {\em and even in
parallel} to that of a linear collider. The latter's goal is to provide more
detailed information on previously discovered New Physics involved in the
electroweak phase transition. Likewise a Super-$B$ factory would provide
precision probes for analyzing whether such New Dynamics has an impact on heavy
flavour dynamics -- a need particularly manifest if the New Physics is housed
under the `big tent' of SUSY. The huge statistics of a Super-$B$ factory and
the comprehensive body of accurate measurements uniquely possible there would
be harnessed in several classes of studies, among them more precise extractions
of $V(ub)/V(cb)$ and $V(td)/V(ts)$, more detailed analyses of $B\to \gamma
X_{s,d}, l^+l^-X$ and novel data on $B\to \tau \nu, \tau \nu D, \nu \bar \nu X$
and maybe even on $\Upsilon (5S) \to B_s \bar B_s$ -- all in addition to a host
of CP asymmetries.Comment: Based on talks given at the 5th Workshop on a Higher Luminosity B
Factory, Sept. 24 - 26, 2003, Izu, Japan; LATEX, 28 pages, no figure

### Searching for T,CP,CPT,and \Delta S = \Delta Q rule violations in the neutral K meson system - a guide

It is known that the existing experimental limit for$CPT$ violation is
rather poor; the 10 \% level at best. The \DSDQ rule is tested only up to 2
\%. In this note, we discuss the possibility of measuring $T, CP, CPT$ and
\DSDQ rule violations in the neutral $K$ meson system. It is shown that not
all the symmetry breaking parameters can be determined at a symmetric $\phi$
factory. Experiments with $K^0$ and $\bar{K}^0$ beams are needed to test
all the symmetries.Comment: RevTex, 43 pages, DPNU 93-0

### A new method of determining $|V_{ub}|$ by the processes $\bar{B} \to \rho l \bar{\nu}$ and \bar{B} \to K^* l \lbar

The differential decay width of the process $\bar{B} \rightarrow \rho l
\bar{\nu}$ is related to that of the process \bar{B} \rightarrow K^* l \lbar
by using $SU(3)$-flavor symmetry and the heavy quark symmetry. The ratio of the
Kobayashi-Maskawa matrix elements is obtained in the zero recoil limit of
$\rho$ and $K^*$, allowing a determination of $|V_{ub}|$.Comment: Latex file 9 pag

### Calculation of Magnetic Penguin Amplitudes in B -> phi K Decays using PQCD Approach

New physics contributions to B decays often arise through chromo-magnetic
penguin operators. To look for new physics effects in B decays, it is useful to
be able to estimate the hadronic matrix elements for the chromo-magnetic
operator. We compute this contribution to B ->phi K decays using PQCD methods.
It is shown that, if the Wilson coefficient of the new physics is same order of
magnitude as that of the Standard Model, this operator gives a non-negligible
contribution compared to that of the Standard Model (about 30%). We also
investigate the value of q^2, which is the momentum transferred by the gluon in
the chromo-magnetic penguin operator. We find that the expectation value
is approximately M^2_B/4, in agreement with a naive guess. This result,
however, is very sensitive to the scale dependence of the Wilson coefficient.
We also show that the matrix element for the chromo-magnetic penguin operator
is independent of the choice of energy scale to a very good approximation.Comment: 15 pages, 3 figures, LaTeX with the PTP style, minor changes of typo

### How well can we predict CP asymmetry in $B\to \pi\pi$, $K\pi$ decays?

Using the perturbative QCD amplitudes for $B\to \pi\pi$ and $B\to K\pi$, we
have performed an extensive study of the parameter space where the theoretical
predictions for the branching ratios are consistent with recent experimental
data. From this allowed range of parameter space, we predict the mixing induced
CP asymmetry for $B \to \pi^+\pi^-$ with about 11% uncertainty and the other CP
asymmetries for $B\to \pi\pi$, $K\pi$ with 40% ~ 47% uncertainty. These errors
are expected to be reduced as we restrict the parameter space by studying other
decay modes and by further improvements in the experimental data.Comment: 15 pages, 4 figures, 2 table

### CP Violation and Nonleptonic B-meson Decays

We discuss the perturbative QCD approach for exclusive non-leptonic two body
B-meson decays. We briefly review its ingredients and some important
theoretical issues related to the factorization approach. PQCD results are
compatible with present experimental data for the charmless B-meson decays. We
predict the possibility of large direct CP violation effects in $B^0 \to
\pi^{+}\pi^{-}$ $(23\pm7 %)$ and $B^0\to K^{+}\pi^{-}$ $(-17\pm5%)$. For
charmed decay $B \to D^{(*)}\pi$, we get large non-factorizable contributions
for Color-suppressed decays and obtain $|a_2/a_1|\sim 0.4-0.5$ and
$Arg(a_2/a_1)\sim -42^{o}$. In the last section we investigate the method to
extract the weak phases $\phi_2$ from $B \to \pi\pi$ decay and $\phi_3$ from
$K\pi$ modes. From BaBar measurement of CP asymmetry for the $\pi^{+}\pi^{-}$
decay, the prefered CKM weak phases are: $\phi_1=(24\pm2)^{o}$, $\phi_2=(78\pm
22)^{o}$ and $\phi_3=(78\pm 22)^{o}$.Comment: Invited talk at the Workshop on the CKM Unitarity Triangle, IPPP
Durham, April 2003 (eConf C0304052). 6 pages LaTeX, 2 eps figures and 3
tables. Correct typos and add references. Final version of the workshop
proceeding

### Getting at the CP Angles

In anticipation for intensive experimental effort on B physics, theorists
have introduced many ingenious ways to measure properties of the unitarity
triangle. We review some of these methods. We will be critical in the hope
that, if there is any defect in them, it can be remedied either theoretically
or experimentally.Comment: Sprocl 15 pages. Talk given (by A.I.S.) at the 7th International
Symposium on Heavy Flavor Physics, Santa Barbara, July 7 - 11, 1997 (to
appear in the proceedings

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