355 research outputs found
Calculating Phases Between B => K* pi Amplitudes
A phase between amplitudes for and plays a crucial role in a method for constraining
Cabibbo-Kobayashi-Maskawa (CKM) parameters. We present a general argument for
destructive interference between amplitudes for and forming together a smaller amplitude.
Applying flavor SU(3) and allowing for conservative theoretical uncertainties,
we obtain lower limits on and its charge-conjugate. Values of
these two phases favored by the BaBar Collaboration are in good agreement with
our bounds.Comment: 12 pages, 6 figures; slight revisions and clarification
Explaining violation traces with finite state natural language generation models
An essential element of any verification technique is that of identifying and communicating to the user, system behaviour which leads to a deviation
from the expected behaviour. Such behaviours are typically made available as long
traces of system actions which would benefit from a natural language explanation
of the trace and especially in the context of business logic level specifications. In
this paper we present a natural language generation model which can be used to
explain such traces. A key idea is that the explanation language is a CNL that is,
formally speaking, regular language susceptible transformations that can be expressed with finite state machinery. At the same time it admits various forms of
abstraction and simplification which contribute to the naturalness of explanations
that are communicated to the user.peer-reviewe
Playing nomic using a controlled natural language
Controlled natural languages have been used in a variety of
domains, to enable information extraction and formal reasoning. One major challenge is that although the syntax
is restricted to enable processing, without a similar restricted domain of application, it is typically difficult to extract
useful results. In this paper we look at the development of
a controlled natural language to reason about contractual
clauses. The language is used to enable human players to
play a variant of Nomic — a game of changing contracts,
whose very nature makes it extremely challenging to mechanise. We present the controlled natural language with
its implementation in the Grammatical Framework, and an
underlying deontic logic used to reason about the contracts
proposed by the players.peer-reviewe
Triple product asymmetries in K, D_(s) and B_(s) decays
One distinguishes between "true" CP violating triple product (TP) asymmetries
which require no strong phases and "fake" asymmetries which are due to strong
phases but require no CP violation. So far a single true TP asymmetry has been
measured in . A general discussion is presented for
T-odd TP asymmetries in four-body decays. It is shown that TP asymmetries
vanish for two identical and kinematically indistinguishable particles in the
final state. Two examples are and . A non-zero TP asymmetry can be expected when non-trivial
kinematic correlations exist, as in the decay . Triple
product asymmetries measured in charmed particle decays indicate an interesting
pattern of final-state interactions. We reiterate a discussion of TP
asymmetries in meson decays to two vector mesons each decaying to a
pseudoscalar pair, extending results to decays where one vector meson decays
into a lepton pair. We derive expressions for time-dependent TP asymmetries for
neutral B decays to flavorless states in terms of the neutral mass
difference and the width-difference . Time-integrated
true CP violating asymmetries, measurable for untagged decays, are shown
to be suppressed by neither nor
if transversity amplitudes for CP-even and CP-odd states involve different weak
phases. In contrast, fake asymmetries require flavor tagging and are suppressed
by the former ratio when time-integrated. We apply our results to and data and suggest an application for .Comment: minor corrections, submitted to Phys. Rev.
A controlled language for the specification of contracts
Controlled natural languages have been used to enable the direct translation from natural language specifications into a formal description. In this paper we make a case for such an approach to write contracts, and translating into a temporal deontic logic. Combining both temporal behaviour and deontic behaviour is challenging both from a natural language and a formal logic perspective. We present both a logic and a controlled natural language and outline how the two can be linked.peer-reviewe
Radiative Decay Using Heavy Quark and Chiral Symmetry
The implications of chiral symmetry and heavy quark
symmetry for the radiative decays , ,
and are discussed. Particular attention is paid to
violating contributions of order . Experimental data on these
radiative decays provide constraints on the coupling.Comment: 9 pages plus 3 pages of figures in POSTSCRIPT file appended to TeX
file (uses harvmac.tex and tables.tex), UCSD/PTH 92-31, CALT-68-1816,
EFI-92-45, CERN-TH.6650/9
Meson Decay Constants from Isospin Mass Splittings in the Quark Model
Decay constants of and mesons are estimated within the framework of a
heavy-quark approach using measured isospin mass splittings in the , ,
and states to isolate the electromagnetic hyperfine interaction between
quarks. The values MeV and MeV are
obtained. Only experimental errors are given; possible theoretical ambiguities,
and suggestions for reducing them, are noted.Comment: 7 pages, LaTeX, EFI-92-3
Robustness of Cosmological Simulations I: Large Scale Structure
The gravitationally-driven evolution of cold dark matter dominates the
formation of structure in the Universe over a wide range of length scales.
While the longest scales can be treated by perturbation theory, a fully
quantitative understanding of nonlinear effects requires the application of
large-scale particle simulation methods. Additionally, precision predictions
for next-generation observations, such as weak gravitational lensing, can only
be obtained from numerical simulations. In this paper, we compare results from
several N-body codes using test problems and a diverse set of diagnostics,
focusing on a medium resolution regime appropriate for studying many
observationally relevant aspects of structure formation. Our conclusions are
that -- despite the use of different algorithms and error-control methodologies
-- overall, the codes yield consistent results. The agreement over a wide range
of scales for the cosmological tests is test-dependent. In the best cases, it
is at the 5% level or better, however, for other cases it can be significantly
larger than 10%. These include the halo mass function at low masses and the
mass power spectrum at small scales. While there exist explanations for most of
the discrepancies, our results point to the need for significant improvement in
N-body errors and their understanding to match the precision of near-future
observations. The simulation results, including halo catalogs, and initial
conditions used, are publicly available.Comment: 32 pages, 53 figures, data from the simulations is available at
http://t8web.lanl.gov/people/heitmann/arxiv, accepted for publication in
ApJS, several minor revisions, reference added, main conclusions unchange
Early-Adulthood Cardiovascular Disease Risk Factor Profiles Among Individuals With and Without Diabetes in the Framingham Heart Study
OBJECTIVE Many studies of diabetes have examined risk factors at the time of diabetes diagnosis instead of considering the lifetime burden of adverse risk factor levels. We examined the 30-year cardiovascular disease (CVD) risk factor burden that participants have up to the time of diabetes diagnosis. RESEARCH DESIGN AND METHODS Among participants free of CVD, incident diabetes cases (fasting plasma glucose ≥126 mg/dL or treatment) occurring at examinations 2 through 8 (1979–2008) of the Framingham Heart Study Offspring cohort were age- and sex-matched 1:2 to controls. CVD risk factors (hypertension, high LDL cholesterol, low HDL cholesterol, high triglycerides, obesity) were measured at the time of diabetes diagnosis and at time points 10, 20, and 30 years prior. Conditional logistic regression was used to compare risk factor levels at each time point between diabetes cases and controls. RESULTS We identified 525 participants with new-onset diabetes who were matched to 1,049 controls (mean age, 60 years; 40% women). Compared with those without diabetes, individuals who eventually developed diabetes had higher levels of hypertension (odds ratio [OR], 2.2; P = 0.003), high LDL (OR, 1.5; P = 0.04), low HDL (OR, 2.1; P = 0.0001), high triglycerides (OR, 1.7; P = 0.04), and obesity (OR, 3.3; P < 0.0001) at time points 30 years before diabetes diagnosis. After further adjustment for BMI, the ORs for hypertension (OR, 1.9; P = 0.02) and low HDL (OR, 1.7; P = 0.01) remained statistically significant. CONCLUSIONS CVD risk factors are increased up to 30 years before diagnosis of diabetes. These findings highlight the importance of a life course approach to CVD risk factor identification among individuals at risk for diabetes
Identification of Neutral B Mesons Using Correlated Hadrons
The identification of the flavor of a neutral meson can make use of
hadrons produced nearby in phase space. Examples include the decay of
``'' resonances or the production of hadrons as a result of the
fragmentation process. Some aspects of this method are discussed, including
time-dependent effects in neutral decays to flavor states, to eigenstates
of CP and to other states, and the effects of possible coherence between
and in the initial state. We study the behavior of the leading
hadrons in -quark jets and the expected properties of resonances.
These are extrapolated from the corresponding resonances, of whose
properties we suggest further studies.Comment: To be submitted to Phys. Rev. D. 26 pages, LaTeX, figures not
included (available upon request). Technion-PH-93-32 / EFI 93-4
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