8,940 research outputs found
B decays dominated by omega-phi mixing
Recently Belle has established the 90% confidence level (CL) upper limit \b
< 9.4 \times 10^{-7} for the branching ratio for , a
process expected to be suppressed by the Okubo-Zweig-Iizuka (OZI) rule
disfavoring disconnected quark diagrams. We use information on --
mixing to establish likely lower bounds on this and related processes. We find
that the Belle result is about a factor of five above our limit, while other
decays such as and , for which
upper limits have been obtained by BaBar, could be observable with similar
improvements in data. We argue that a significant enhancement of our predicted
decay rates by rescattering is unlikely.Comment: paragraph added, submitted to Physics Letters
A radiative transfer scheme for cosmological reionization based on a local Eddington tensor
A radiative transfer scheme is presented, based on a moment description of
the equation of radiative transfer and the so-called ``M1 closure model'' for
the Eddington tensor. This model features a strictly hyperbolic transport step
for radiation: it has been implemented using standard Godunov--like techniques
in a new code called ATON. Coupled to simple models of ionization chemistry and
photo-heating, ATON is able to reproduce the results of other schemes on a
various set of standard tests such as the expansion of a HII region, the
shielding of the radiation by dense clumps and cosmological ionization by
multiple sources. Being simple yet robust, such a scheme is intended to be
naturally and easily included in grid--based cosmological fluid solvers.Comment: 14 pages, 13 figures, submitted to MNRA
Lacunarity of Fractal Superlattices: a Remote Estimation using Wavelets
The lacunarity provides a useful parameter for describing the distribution of gap sizes in discrete self-similar (fractal) superlattices and is used in addition to the similarity dimension to describe fractals. We show here that lacunarity, as well as the similarity dimension, can be remotely estimated from the wavelet analysis of superlattices impulse response. As a matter of fact, the skeletonâthe set of wavelet-transform modulus-maximaâof the reflected signal overlaps two hierarchical structures in the time-scale domain: such that one allows the direct remote extraction of the similarity dimension, while the other may provide an accurate estimation of the lacunarity of the interrogated superlattice. Criteria for the choice of the mother wavelet are established for impulse response corrupted by additive Gaussian white noise
Alien Registration- Aubert, Leandre L. (Monmouth, Kennebec County)
https://digitalmaine.com/alien_docs/16281/thumbnail.jp
An Improved Standard Model Prediction Of BR(B -> tau nu) And Its Implications For New Physics
The recently measured B -> tau nu branching ratio allows to test the Standard
Model by probing virtual effects of new heavy particles, such as a charged
Higgs boson. The accuracy of the test is currently limited by the experimental
error on BR(B -> tau nu) and by the uncertainty on the parameters fB and |Vub|.
The redundancy of the Unitarity Triangle fit allows to reduce the error on
these parameters and thus to perform a more precise test of the Standard Model.
Using the current experimental inputs, we obtain BR(B -> tau nu)_SM = (0.84 +-
0.11)x10^{-4}, to be compared with BR(B -> tau nu)_exp = (1.73 +-
0.34)x10^{-4}. The Standard Model prediction can be modified by New Physics
effects in the decay amplitude as well as in the Unitarity Triangle fit. We
discuss how to disentangle the two possible contributions in the case of
minimal flavour violation at large tan beta and generic loop-mediated New
Physics. We also consider two specific models with minimal flavour violation:
the Type-II Two Higgs Doublet Model and the Minimal Supersymmetric Standard
Model.Comment: 7 pages, 13 figures, 1 table. v2: added references and discussion of
B -> D tau nu in the 2HDM. v3: added Bs->mumu in the 2HDM. Final version to
appear in PL
CLEO Dalitz plot results
Present and future contributions of the CLEO experiment to the study of
Dalitz plots are presented. Such Dalitz plots can be of help in determining
weak phases from decays.Comment: 4 pages, 6 figures, presented at Beauty 2005, Assisi, Italy, June
20-24, 2005, on behalf of CLEO Collaboration, one reference adde
Time Reversal Violation from the entangled B0-antiB0 system
We discuss the concepts and methodology to implement an experiment probing
directly Time Reversal (T) non-invariance, without any experimental connection
to CP violation, by the exchange of "in" and "out" states. The idea relies on
the B0-antiB0 entanglement and decay time information available at B factories.
The flavor or CP tag of the state of the still living neutral meson by the
first decay of its orthogonal partner overcomes the problem of irreversibility
for unstable systems, which prevents direct tests of T with incoherent particle
states. T violation in the time evolution between the two decays means
experimentally a difference between the intensities for the time-ordered (l^+
X, J/psi K_S) and (J/psi K_L, l^- X) decays, and three other independent
asymmetries. The proposed strategy has been applied to simulated data samples
of similar size and features to those currently available, from which we
estimate the significance of the expected discovery to reach many standard
deviations.Comment: 17 pages, 2 figures, 6 table
Exciton spin dynamics and photoluminescence polarization of CdSe/CdS dot-in-rod nanocrystals in high magnetic fields
The exciton spin dynamics and polarization properties of the related emission
are investigated in colloidal CdSe/CdS dot-in-rod (DiR) and spherical
core/shell nanocrystal (NC) ensembles by magneto-optical photoluminescence (PL)
spectroscopy in magnetic fields up to 15 T. It is shown that the degree of
circular polarization (DCP) of the exciton emission induced by the magnetic
field is affected by the NC geometry as well as the exciton fine structure and
can provide information on nanorod orientation. A theory to describe the
circular and linear polarization properties of the NC emission in magnetic
field is developed. It takes into account phonon mediated coupling between the
exciton fine structure states as well as the dielectric enhancement effect
resulting from the anisotropic shell of DiR NCs. This theoretical approach is
used to model the experimental results and allows us to explain most of the
measured features. The spin dynamics of the dark excitons is investigated in
magnetic fields by time-resolved photoluminescence. The results highlight the
importance of confined acoustic phonons in the spin relaxation of dark
excitons. The bare core surface as well as the core/shell interface give rise
to an efficient spin relaxation channel, while the surface of core/shell NCs
seems to play only a minor role.Comment: 18 pages, 15 figure
Final state interactions in B+- to K+ K- K+- decays
Charged B decays to three charged kaons are analysed in the framework of the
QCD factorization approach. The strong final state K+K-interactions are
described using the kaon scalar and vector form factors. The scalar non-strange
and strange form factors at low K+K- effective masses are constrained by chiral
perturbation theory and satisfy the two-body unitarity conditions. The latter
stem from the properties of the meson-meson amplitudes which describe all
possible S-wave transitions between three coupled channels consisting of two
kaons, two pions and four pions. The vector form factors are fitted to the data
on the electromagnetic kaon interactions. The model results are compared with
the Belle and BaBar data. Away from phi(1020) resonance, in the S-wave
dominated K+K- mass spectra, a possibility for a large CP asymmetry is
identified.Comment: 7 pages, 4 figures, modified version published in Physics Letters
The UTfit Collaboration Average of D meson mixing data: Spring 2012
We derive constraints on the parameters , and
that describe meson mixing using all available data, allowing
for CP violation. We also provide posterior distributions and predictions for
observable parameters appearing in physics.Comment: 5 pages, 3 figure
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