2,148 research outputs found
Phase Diagrams for Sonoluminescing Bubbles
Sound driven gas bubbles in water can emit light pulses. This phenomenon is
called sonoluminescence (SL). Two different phases of single bubble SL have
been proposed: diffusively stable and diffusively unstable SL. We present phase
diagrams in the gas concentration vs forcing pressure state space and also in
the ambient radius vs gas concentration and vs forcing pressure state spaces.
These phase diagrams are based on the thresholds for energy focusing in the
bubble and two kinds of instabilities, namely (i) shape instabilities and (ii)
diffusive instabilities. Stable SL only occurs in a tiny parameter window of
large forcing pressure amplitude atm and low gas
concentration of less than of the saturation. The upper concentration
threshold becomes smaller with increasing forcing. Our results quantitatively
agree with experimental results of Putterman's UCLA group on argon, but not on
air. However, air bubbles and other gas mixtures can also successfully be
treated in this approach if in addition (iii) chemical instabilities are
considered. -- All statements are based on the Rayleigh-Plesset ODE
approximation of the bubble dynamics, extended in an adiabatic approximation to
include mass diffusion effects. This approximation is the only way to explore
considerable portions of parameter space, as solving the full PDEs is
numerically too expensive. Therefore, we checked the adiabatic approximation by
comparison with the full numerical solution of the advection diffusion PDE and
find good agreement.Comment: Phys. Fluids, in press; latex; 46 pages, 16 eps-figures, small
figures tarred and gzipped and uuencoded; large ones replaced by dummies;
full version can by obtained from: http://staff-www.uni-marburg.de/~lohse
Bubble Shape Oscillations and the Onset of Sonoluminescence
An air bubble trapped in water by an oscillating acoustic field undergoes
either radial or nonspherical pulsations depending on the strength of the
forcing pressure. Two different instability mechanisms (the Rayleigh--Taylor
instability and parametric instability) cause deviations from sphericity.
Distinguishing these mechanisms allows explanation of many features of recent
experiments on sonoluminescence, and suggests methods for finding
sonoluminescence in different parameter regimes.Comment: Phys. Rev. Lett., in pres
Statement from the American Linear Collider Committee to the P5 subpanel
This statement from the American Linear Collider Committee to the P5 subpanel
has three purposes. It presents a brief summary of the case for an
Higgs factory that has emerged from Snowmass 2021. It highlights the special
virtues of the ILC that are shared with other linear colliders but not with
circular colliders. Finally, it calls attention to the resources available in
the ILC White Paper for Snowmass (arXiv:2203.07622). The ALCC urges P5 to move
the Higgs factory forward as a global project by assigning the idea of an
Higgs factory high priority, initiating a global discussion of the
technology choice and cost sharing, and offering the option of siting the Higgs
factory in the U.S.Comment: 6 page
Measurement of the Branching Fraction of the Decay in Fully Reconstructed Events at Belle
We present an analysis of the exclusive
decay, where represents an
electron or a muon, with the assumption of charge-conjugation symmetry and
lepton universality. The analysis uses the full data sample
collected by the Belle detector, corresponding to 711 fb of integrated
luminosity. We select the events by fully reconstructing one meson in
hadronic decay modes, subsequently determining the properties of the other
meson. We extract the signal yields using a binned maximum-likelihood fit to
the missing-mass squared distribution in bins of the invariant mass of the two
pions or the momentum transfer squared. We measure a total branching fraction
of , where the
uncertainties are statistical and systematic, respectively. This result is the
first reported measurement of this decay.Comment: 23 pages, 19 figure
Measurement of branching fraction and direct asymmetry in charmless decays at Belle
We report a study of the charmless hadronic decay of the charged meson to
the three-body final state . The results are based on a data
sample that contains pairs collected at the
resonance with the Belle detector at the KEKB asymmetric-energy
collider. The measured inclusive branching fraction and the direct
asymmetry are and
, respectively, where the first uncertainties are
statistical and the second are systematic. The invariant mass
distribution of the signal candidates shows an excess in the region below
GeV/, which is consistent with the previous studies from BaBar and LHCb.
In addition, strong evidence of a large direct asymmetry is found in the
low-invariant-mass region.Comment: 7 pages, 3 figure
Measurement of the lepton polarization and in the decay
We report the first measurement of the lepton polarization
in the decay as
well as a new measurement of the ratio of the branching fractions , where
denotes an electron or a muon, and the is reconstructed in the modes
and .
We use the full data sample of pairs recorded
with the Belle detector at the KEKB electron-positron collider. Our results,
and
, are
consistent with the theoretical predictions of the Standard Model.Comment: 7 pages, 2 figures, submitted to Physical Review Letters; one figure
was removed from the first versio
Study of Excited States Decaying into and Baryons
Using a data sample of 980 of annihilation data
taken with the Belle detector operating at the KEKB asymmetric-energy
collider, we report the results of a study of excited states that
decay, via the emission of photons and/or charged pions, into or
ground state charmed-strange baryons. We present new measurements of
the masses of all members of the , ,
, , and isodoublets, measurements of
the intrinsic widths of those that decay strongly, and evidence of previously
unknown transitions.Comment: Submitted to PR
Observation of and search for violation in radiative charm decays
We report the first observation of the radiative charm decay and the first search for violation in decays , , and , using a data sample of
943 fb collected with the Belle detector at the KEKB asymmetric-energy
collider. The branching fraction is measured to be , where the first
uncertainty is statistical and the second is systematic. The obtained
asymmetries, , , and
, are consistent with no violation. We also present an improved
measurement of the branching fractions and
Search for decays with semileptonic tagging at Belle
We present the results of a search for the rare decays , where stands for and . The results are
obtained with pairs collected with the Belle
detector at the KEKB collider. We reconstruct one meson in a
semileptonic decay and require a single meson but nothing else on the
signal side. We observe no significant signal and set upper limits on the
branching fractions. The limits set on the , , , ,
, and channels
are the world's most stringent.Comment: Submitted to PR
Invariant-mass and fractional-energy dependence of inclusive production of di-hadrons in annihilation at 10.58 GeV
The inclusive cross sections for di-hadrons of charged pions and kaons
() in electron-positron annihilation are reported. They
are obtained as a function of the total fractional energy and invariant mass
for any di-hadron combination in the same hemisphere as defined by the thrust
event-shape variable and its axis. Since same-hemisphere di-hadrons can be
assumed to originate predominantly from the same initial parton, di-hadron
fragmentation functions are probed. These di-hadron fragmentation functions are
needed as an unpolarized baseline in order to quantitatively understand related
spin-dependent measurements in other processes and to apply them to the
extraction of quark transversity distribution functions in the nucleon. The
di-hadron cross sections are obtained from a data sample
collected at or near the resonance with the Belle detector at
the KEKB asymmetric-energy collider.Comment: 21 pages, 18 figures plus 25 figures in supplemental material,
submitted to PR
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