3,542 research outputs found
Survival before annihilation in Psi-prime decays
We extend the simple scenario for decays suggested a few years ago.
The pair in the does not annihilate directly into three
gluons but rather survives before annihilating. An interesting prediction is
that a large fraction of all decays could originate from the channel which we urge experimentalists to identify. Our model
solves the problem of the apparent hadronic excess in decays as well as
the puzzle since, in our view, the two-body decays of the are
naturally of electromagnetic origin. Further tests of this picture are
proposed, e.g. .Comment: 6 pages, no figur
Characters of the W3 algebra
Traces of powers of the zero mode in the W3 Algebra have recently been found
to be of interest, for example in relation to Black Hole thermodynamics, and
arise as the terms in an expansion of the full characters of the algebra. We
calculate the first few such powers in two cases. Firstly, we find the traces
in the 3-state Potts model by using null vectors to derive modular differential
equations for the traces. Secondly, we calculate the exact results for Verma
module representations. We compare our two methods with each other and the
result of brute-force diagonalisation for low levels and find complete
agreement.Comment: v2: Numerous small changes, version to appear in JHEP, 22 pages. v3:
Typos corrected, matches published version, 22 page
Hadronic Phases and Isospin Amplitudes in and Decays
Hadronic phase in and channels are calculated a la
Regge. At the D mass one finds and in good agreement with the CLEO data while at the B
mass these angles are predicted to be, respectively, and .
With the hadronic phase taken into account, a quark
diagram decomposition of the isospin invariant amplitudes in
decays fits the data provided the exchange diagram contribution is about 1/3 of
the tree level one.Comment: 10pages,late
Controlling the dynamics of a coupled atom-cavity system by pure dephasing : basics and potential applications in nanophotonics
The influence of pure dephasing on the dynamics of the coupling between a
two-level atom and a cavity mode is systematically addressed. We have derived
an effective atom-cavity coupling rate that is shown to be a key parameter in
the physics of the problem, allowing to generalize the known expression for the
Purcell factor to the case of broad emitters, and to define strategies to
optimize the performances of broad emitters-based single photon sources.
Moreover, pure dephasing is shown to be able to restore lasing in presence of
detuning, a further demonstration that decoherence can be seen as a fundamental
resource in solid-state cavity quantum electrodynamics, offering appealing
perspectives in the context of advanced nano-photonic devices.Comment: 10 pages, 7 figure
Electric field sensing with a scanning fiber-coupled quantum dot
We demonstrate the application of a fiber-coupled quantum-dot-in-a-tip as a
probe for scanning electric field microscopy. We map the out-of-plane component
of the electric field induced by a pair of electrodes by measurement of the
quantum-confined Stark effect induced on a quantum dot spectral line. Our
results are in agreement with finite element simulations of the experiment.
Furthermore, we present results from analytic calculations and simulations
which are relevant to any electric field sensor embedded in a dielectric tip.
In particular, we highlight the impact of the tip geometry on both the
resolution and sensitivity.Comment: 10 pages, 4 figure
Final State Interaction Phases in Decay Amplitudes
A simple Regge pole model for scattering explains the large between isospin amplitudes which is observed at the D meson mass
(). It predicts
at the B mass. Implications for () decays and extensions of the
model to other two-body decay channels are briefly discussed.Comment: 8pages,late
Phases and Amplitudes in Inclusive and Decays
In inclusive decays of the (3097), electromagnetic and gluonic
annihilation amplitudes add incoherently, namely they are 90 out of
phase. We argue that this incoherence must persist in each exclusive decay
channel. For inclusive (3686) decays, we suggest the absence of a
significant direct annihilation amplitude into three gluons and propose a new
amplitude via QCD anomalies and the (3526) off shell. Phenomenological
implications for exclusive decay channels are pointed out.Comment: 10 page
Trace anomalies and the rule
Trace Anomaly Dominance in weak -decays successfully reproduces the
selection rule results, as observed in and .Comment: 10 pages, no figur
Monitoring stimulated emission at the single photon level in one-dimensional atoms
We theoretically investigate signatures of stimulated emission at the single
photon level for a two-level atom interacting with a one-dimensional light
field. We consider the transient regime where the atom is initially excited,
and the steady state regime where the atom is continuously driven with an
external pump. The influence of pure dephasing is studied, clearly showing that
these effects can be evidenced with state of the art solid state devices. We
finally propose a scheme to demonstrate the stimulation of one optical
transition by monitoring another one, in three-level one-dimensional atoms.Comment: 4 pages, 4 figures. Improved introduction; Comments adde
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