94 research outputs found
Sampling considerations when analyzing micrometric-sized particles in a liquid jet using laser induced breakdown spectroscopy
International audiencePollution of water is a matter of concern all over the earth. Particles are known to play an important role in the transportation of pollutants in this medium. In addition, the emergence of new materials such as NOAA (Nano-Objects, their Aggregates and their Agglomerates) emphasizes the need to develop adapted instruments for their detection. Surveillance of pollutants in particulate form in waste waters in industries involved in nanopartide manufacturing and processing is a telling example of possible applications of such instrumental development. The LIBS (laser-induced breakdown spectroscopy) technique coupled with the liquid jet as sampling mode for suspensions was deemed as a potential candidate for on-line and real time monitoring. With the final aim in view to obtain the best detection limits, the interaction of nanosecond laser pulses with the liquid jet was examined. The evolution of the volume sampled by laser pulses was estimated as a function of the laser energy applying conditional analysis when analyzing a suspension of micrometric-sized particles of borosilicate glass. An estimation of the sampled depth was made. Along with the estimation of the sampled volume, the evolution of the SNR (signal to noise ratio) as a function of the laser energy was investigated as well. Eventually, the laser energy and the corresponding fluence optimizing both the sampling volume and the SNR were determined. The obtained results highlight intrinsic limitations of the liquid jet sampling mode when using 532 nm nanosecond laser pulses with suspensions
Improvements to the Method of Dispersion Relations for B Nonleptonic Decays
We bring some clarifications and improvements to the method of dispersion
relations in the external masses variables, that we proposed recently for
investigating the final state interactions in the B nonleptonic decays. We
first present arguments for the existence of an additional term in the
dispersion representation, which arises from an equal-time commutator in the
LSZ formalism and can be approximated by the conventional factorized amplitude.
The reality properties of the spectral function and the Goldberger-Treiman
procedure to perform the hadronic unitarity sum are analyzed in more detail. We
also improve the treatment of the strong interaction part by including the
contributions of both t and u-channel trajectories in the Regge amplitudes.
Applications to the and decays are
presented.Comment: 16 pages, 4 new figures. modifications of the dispersion
representatio
Lepton flavor violation two-body decays of quarkoniums
In this paper we firstly study various model-independent bounds on lepton
flavor violation (LFV) in processes of , and
two-body decays, then calculate their branch ratios % By using the constraints
from other ways, we obtain %the indirect bounds of in models of the leptoquark, violating
MSSM and topcolor assisted technicolor(TC2) models.Comment: 14 pages, 4 figures, submitted to PR
Combining CP Asymmetries in Decays
We prove an approximate relation, to leading order in dominant terms, between
CP-violating rate differences in and
. We show how data from these two processes may be
combined in order to enhance the significance of a nonzero result.Comment: 9 pages, latex, no figures, submitted to Phys. Rev. Letters, revise
Rescattering Information from Decays
Rescattering effects can modify the dependence on the weak phase of the ratio of rates for and . A test for these effects based on the
processes has been suggested. It is pointed out that the
rates for the processes , which are expected to be {\it
dominated} by rescattering and for which considerably better experimental
bounds exist, are likely to provide a more stringent constraint on these
effects.Comment: 22 pages, latex, 7 figures, to be published in Phys. Rev. D. Minor
corrections and addition
Validation of a liquid chromatography-tandem mass spectrometry screening method to monitor 58 antibiotics in milk: a qualitative approach
Taming the Penguin in the B0(t) -> Pi+Pi- CP-asymmetry: Observables and Minimal Theoretical Input
Penguin contributions, being not negligible in general, can hide the
information on the CKM angle alpha coming from the measurement of the
time-dependent B0(t) -> pi+pi- CP-asymmetry. Nevertheless, we show that this
information can be summarized in a set of simple equations, expressing alpha as
a multi-valued function of a single theoretically unknown parameter, which
conveniently can be chosen as a well-defined ratio of penguin to tree
amplitudes. Using these exact analytic expressions, free of any assumption
besides the Standard Model, and some reasonable hypotheses to constrain the
modulus of the penguin amplitude, we derive several new upper bounds on the
penguin-induced shift |2alpha-2alpha_eff|, generalizing the recent result of
Grossman and Quinn. These bounds depend on the averaged branching ratios of
some decays (pi0pi0, K0K0bar, K+-pi-+) particularly sensitive to the penguin.
On the other hand, with further and less conservative approximations, we show
that the knowledge of the B+- -> Kpi+- branching ratio alone gives sufficient
information to extract the free parameter without the need of other
measurements, and without knowing |V_td| or |V_ub|. More generally, knowing the
modulus of the penguin amplitude with an accuracy of ~30% might result in an
extraction of alpha competitive with the experimentally more difficult isospin
analysis. We also show that our framework allows to recover most of the
previous approaches in a transparent and simple way, and in some cases to
improve them. In addition we discuss in detail the problem of the various kinds
of discrete ambiguities.Comment: LaTeX2e, 44 pages, 9 figures (from 18 postscript files) included with
epsf. Minor changes, references updated. New CLEO results from ICHEP'98 are
taken into account. To appear in Phys. Rev.
On Large Final-State Phases in Heavy Meson Decays
An attempt is made to identify circumstances under which the weak decays of
and mesons may display large differences between eigenphases of strong
final-state interactions. There are several cases in which rescattering from
other final states appears to enhance decay rates with respect to estimates
based on the factorization hypothesis.Comment: 24 pages, latex, 4 figures, to be submitted to Phys. Rev.
Final-State Phases in Charmed Meson Two-Body Nonleptonic Decays
Observed decay rates indicate large phase differences among the amplitudes
for the charge states in and but
relatively real amplitudes in the charge states for . This
feature is traced using an SU(3) flavor analysis to a sign flip in the
contribution of one of the amplitudes contributing to the latter processes in
comparison with its contribution to the other two sets. This amplitude may be
regarded as an effect of rescattering and is found to be of magnitude
comparable to others contributing to charmed particle two-body nonleptonic
decays.Comment: 19 pages, latex, 4 figures, to be submitted to Phys. Rev.
Bounding the penguin effects on determinations of from decays
In the absence of the QCD penguin contributions a measurement of the
time-dependent asymmetry in the decay gives directly the
weak angle . Several bounds have been proposed in the literature on the
magnitude of the penguin effects on this determination, the prototype of which
is the isospin bound of Grossman and Quinn. It is pointed out that large strong
final state interactions could cause these bounds to overestimate the real
penguin effect. A new flavor SU(3) bound is proposed, requiring only the
charge-averaged branching ratios for and ,
which exactly takes into account all relevant amplitudes and electroweak
penguin effects. This bound on the penguin-induced error on the determination
of the weak phase holds even without a knowledge of the direct CP
asymmetry in the channel.Comment: 10 pages ReVTeX with 3 included eps figure
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