117 research outputs found
Quantum trajectory pictures of laser cooling
We have applied the method of single atom trajectories to study the mechanism behind some
cooling schemes in laser cooling. In several cases we recognize the cooling mechanism as being due
to a "Sisyphus" process, where the atoms move in a spatially varying light shift potential and are
optically pumped towards the most light shifted states. In other cases we identify a "Sisyphus"
process in time, where the light shift is constant and the force on the atom alternates between
positive and negative. This process is interrupted by quantum jumps at random instants and in
each case we depict the mechanism leading to a cooling force on the atom. In the special case of
sub-Doppler laser cooling in a strong magnetic field we obtain 12 jump operators and identify the
jump operators responsible for the cooling. The versatility of the single atom trajectory method
allows it to be applied to any cooling process and is therefore a very valuable tool in unraveling the
physical mechanisms behind cooling processes
Vus and lepton universality from kaon decays with the KLOE detector
KLOE has measured most decay branching ratios of Ks, Kl and K+/- mesons. It
has also measured the Kl and the K+- lifetime and determined the shape of the
form factors involved in kaon semileptonic decays. We present in the following
a description of the above measurements and a well organized compendium of all
of our data, with particular attention to correlations. These data provide the
basis for the determination of the CKM parameter Vus and a test of the
unitarity of the quark flavor mixing matrix. We also test lepton universality
and place bounds on new physics using measurements of Vus from Kl2 and Kl3
decays.Comment: 23 pages, 12 figures. Submitted to JHE
ESA's wind Lidar mission ADM-AEOLUS; on-going scientific activities related to calibration, retrieval and instrument operation
The Earth Explorer Atmospheric Dynamics Mission
(ADM-Aeolus) of ESA will be the first-ever satellite to
provide global observations of wind profiles from
space. Its single payload, namely the Atmospheric
Laser Doppler Instrument (ALADIN) is a directdetection
high spectral resolution Doppler Wind Lidar
(DWL), operating at 355 nm, with a fringe-imaging
receiver (analysing aerosol and cloud backscatter) and a
double-edge receiver (analysing molecular backscatter).
In order to meet the stringent mission requirements on
wind retrieval, ESA is conducting various science
support activities for the consolidation of the on-ground
data processing, calibration and sampling strategies.
Results from a recent laboratory experiment to study
Rayleigh-Brillouin scattering and improve the
characterisation of the molecular lidar backscatter
signal detected by the ALADIN double-edge Fabry-
Perot receiver will be presented in this paper. The
experiment produced the most accurate ever-measured
Rayleigh-Brillouin scattering profiles for a range of
temperature, pressure and gases, representative of
Earth’s atmosphere. The measurements were used to
validate the Tenti S6 model, which is implemented in
the ADM-Aeolus ground processor.
First results from the on-going Vertical Aeolus
Measurement Positioning (VAMP) study will be also
reported. This second study aims at the optimisation of
the ADM-Aeolus vertical sampling in order to
maximise the information content of the retrieved
winds, taking into account the atmospheric dynamical
and optical heterogeneity. The impact of the Aeolus
wind profiles on Numerical Weather Prediction (NWP)
and stratospheric circulation modelling for the different
vertical sampling strategies is also being estimated
Measurement of the absolute branching ratios for semileptonic K+/- decays with the KLOE detector
Using a sample of over 600 million phi->K+K- decays collected at the Dafne
e+e- collider, we have measured with the KLOE detector the absolute branching
ratios for the charged kaon semileptonic decays, K+/- -> p0 e nu (gamma) (Ke3)
and K+/- -> p0 mu nu (gamma) (Kmu3). The results, BR(Ke3) = 0.04965 +/-
0.00038_{stat} +/- 0.00037_{syst} and BR(Kmu3) = 0.03233 +/- 0.00029_{stat} +/-
0.00026_{syst}, are inclusive of radiation. Accounting for correlations, we
derive the ratio Kmu3/Ke3 = 0.6511+/-0.0064. Using the semileptonic form
factors measured in the same experiment, we obtain V_{us}f_{+}(0) = 0.2141 +/-
0.0013.Comment: 13 pages, 3 figures, submitted to JHEP. v2: minor revisions required
by JHEP, v3: final version published by JHEP (replacement of 2 incorrect
affiliations)link: http://www.iop.org/EJ/abstract/1029-8479/2008/02/09
Precision measurement of and determination of the contribution to the muon anomaly with the KLOE detector
We have measured the ratio
, with the KLOE detector at DANE for a total integrated
luminosity of 240 pb. From this ratio we obtain the cross section
. From the cross section we determine the
pion form factor and the two-pion contribution to the muon anomaly
for GeV, = . This result confirms the
current discrepancy between the Standard Model calculation and the experimental
measurement of the muon anomaly.Comment: 18 pages, 8 figures, minor text corrections, one table added, version
to appear on Physics Letters
Precise measurements of the eta and the neutral kaon meson masses with the KLOE detector
We present precise measurements of the eta and K0 masses using the processes
phi to eta gamma, eta to gamma gamma and phi to Ks Kl, Ks to pi+ pi-. The K0
mass measurement, M_K=497.583 +/- 0.005 (stat) +/- 0.020 (syst) MeV, is in
acceptable agreement with the previous measurements but is more accurate. We
find m(eta) = 547.874 +/- 0.007 (stat) +/- 0.031 (syst) MeV. Our value is the
most accurate to date and is in agreement with two recent measurements based on
eta decays, but is inconsistent, by about 10 sigma, with a measurement of
comparable precision based on eta production at threshold.Comment: 15 pages, 8 figures Submitted to Physics Letters
Charged Kaon K \to 3 pi CP Violating Asymmetries at NLO in CHPT
We give the first full next-to-leading order analytical results in Chiral
Perturbation Theory for the charged Kaon K \to 3 pi slope g and decay rates
CP-violating asymmetries. We have included the dominant Final State
Interactions at NLO analytically and discussed the importance of the unknown
counterterms. We find that the uncertainty due to them is reasonable just for
\Delta g_C, i.e. the asymmetry in the K^+ \to pi^+ pi^+ pi^- slope g; we get
\Delta g_C = -(2.4 +- 1.2) 10^{-5}. The rest of the asymmetries are very
sensitive to the unknown counterterms. In particular, the decay rate
asymmetries can change even sign. One can use this large sentivity to get
valuable information on those counterterms and on Im(G_8) coupling --very
important for the CP-violating parameter epsilon'_K-- from the eventual
measurement of these asymmetries. We also provide the one-loop O(e^2 p^2)
electroweak octet contributions for the neutral and charged Kaon K \to 3 pi
decays.Comment: 43+2 pages, 2 figures. Version accepted in JHEP. Small changes in the
final numerics of CP asymmetries due to change in input valu
- …