1,744 research outputs found
Fractal dimensions of the Q-state Potts model for the complete and external hulls
Fortuin-Kastelyn clusters in the critical -state Potts model are
conformally invariant fractals. We obtain simulation results for the fractal
dimension of the complete and external (accessible) hulls for Q=1, 2, 3, and 4,
on clusters that wrap around a cylindrical system. We find excellent agreement
between these results and theoretical predictions. We also obtain the
probability distributions of the hull lengths and maximal heights of the
clusters in this geometry and provide a conjecture for their form.Comment: 9 pages 4 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.
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
Role of Charm Factory in Extracting CKM-Phase Information via B --> DK
In this paper we study the impact of data that can be obtained from a Charm
Factory on the determination of the CKM parameter gamma from decays of the form
B -> D0 K where the D0 decays to specific inclusive and exclusive final states.
In particular, for each exclusive final state , the charm factory can
determine the strong phase difference between D0-> f and D0-bar -> f by
exploiting correlations in psi(3770)-> D0 D0-bar. This provides crucial input
to the determination of gamma via the interference of B+- -> K+- D0 -> f with
B+- -> K+- D0-bar -> f. We discuss how the method may be generalized to
inclusive final states and illustrate with a toy model how such methods may
offer one of the best means to determine gamma with 10^8-10^9 B-mesons.Comment: 12 pages, 7 figures, Version 2: Fixed typos; add reference; Version
3: fixed latex glitc
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
Acromegaly, Mr Punch and caricature.
The origin of Mr Punch from the Italian Pulcinella of the Commedia dell'arte is well known but his feature, large hooked nose, protruding chin, kyphosis and sternal protrusion all in an exaggerated form also suggest the caricature of an acromegalic. This paper looks at the physical characteristics of acromegaly, the origin of Mr Punch and the development of caricature linking them together in the acromegalic caricature that now has a life of its own
Triple-Product Correlations in B -> V1 V2$ Decays and New Physics
In this paper we examine T-violating triple-product correlations (TP's) in B
-> V1 V2 decays. TP's are excellent probes of physics beyond the standard model
(SM) for two reasons: (i) within the SM, most TP's are expected to be tiny, and
(ii) unlike direct CP asymmetries, TP's are not suppressed by the small strong
phases which are expected in B decays. TP's are obtained via the angular
analysis of B -> V1 V2. In a general analysis based on factorization, we
demonstrate that the most promising decays for measuring TP's in the SM involve
excited final-state vector mesons, and we provide estimates of such TP's. We
find that there are only a handful of decays in which large TP's are possible,
and the size of these TP's depends strongly on the size of nonfactorizable
effects. We show that TP's which vanish in the SM can be very large in models
with new physics. The measurement of a nonzero TP asymmetry in a decay where
none is expected would specifically point to new physics involving large
couplings to the right-handed b-quark.Comment: 42 pages, LaTeX, no figures. Title changed, several explanatory
paragraphs added, references added, analysis and conclusions unchange
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