348 research outputs found
An Analysis
In lieu of an abstract, below is the essay\u27s first paragraph.
Molière, complying with the demands of Louis XIV of France, presented in 1670 a remarkable parody on Turkish customs and language. Le Bourgeois Gentilhomme has brought the plaudits of critics and audiences alike since that time. The play or piece is composed of three acts of character comedy in the folly on Monsieur Jourdain, and two of exaggeration and parody in the events leading up to and the Turkish ceremony. The action develops through a series of episodes rather than a well knit, unified intrigue. Superimposed on the satire on society is a whole-hearted humor prompted by the ignorance and credulity of the central figure, Jourdain, a tradesman who wishes to become a gentleman. He is not an arbitrary figure or character type, but a real human being with exaggerated idiosyncrasies. Molière had associated with this type character in his father\u27s shop. Some critics say that the author would have liked to write of this subject with a more exalted humor, but hurriedly debased it to farce in an effort to suit the wishes of the king
Measurement of the Reaction in Search for the Recently Observed Resonance Structure in and systems
Exclusive measurements of the quasi-free reaction have
been performed by means of collisions at = 1.2 GeV using the WASA
detector setup at COSY. Total and differential cross sections have been
obtained covering the energy region = (2.35 - 2.46) GeV, which
includes the region of the ABC effect and its associated resonance structure.
No ABC effect, {\it i.e.} low-mass enhancement is found in the
-invariant mass spectrum -- in agreement with the constraint from
Bose statistics that the isovector pion pair can not be in relative s-wave. At
the upper end of the covered energy region -channel processes for Roper,
and excitations provide a reasonable description
of the data, but at low energies the measured cross sections are much larger
than predicted by such processes. Adding a resonance amplitude for the
resonance at =~2.37 GeV with =~70 MeV and observed
recently in and reactions leads to an
agreement with the data also at low energies
Charge Symmetry Breaking in dd->4He{\pi}0 with WASA-at-COSY
Charge symmetry breaking (CSB) observables are a suitable experimental tool
to examine effects induced by quark masses on the nuclear level. Previous high
precision data from TRIUMF and IUCF are currently used to develop a consistent
description of CSB within the framework of chiral perturbation theory. In this
work the experimental studies on the reaction dd->4He{\pi}0 have been extended
towards higher excess energies in order to provide information on the
contribution of p-waves in the final state. For this, an exclusive measurement
has been carried out at a beam momentum of p=1.2 GeV/c using the WASA-at-COSY
facility. The total cross section amounts to sigma(tot) = (118 +- 18(stat) +-
13(sys) +- 8(ext)) pb and first data on the differential cross section are
consistent with s-wave pion production.Comment: 14 pages, 5 figure
Search for the eta-mesic 4He with WASA-at-COSY detector
An exclusive measurement of the excitation function for the dd->3Heppi-
reaction was performed at the Cooler Synchrotron COSY-Juelich with the
WASA-at-COSY detection system. The data were taken during a slow acceleration
of the beam from 2.185 GeV/c to 2.400 GeV/c crossing the kinematic threshold
for the eta meson production in the dd->4He-eta reaction at 2.336 GeV/c. The
corresponding excess energy with respect to the 4He-eta system varied from
-51.4MeV to 22MeV. The integrated luminosity in the experiment was determined
using the dd->3Hen reaction. The shape of the excitation function for the
dd->3Heppi- was examined. No signal of the 4He-eta bound state was observed. An
upper limit for the cross-section for the bound state formation and decay in
the process dd->(4He-eta)bound->3Heppi- was determined on the 90% confidence
level and it varies from 20nb to 27nb for the bound state width ranging from
5MeV to 35MeV, respectively.Comment: 8 pages, 9 figure
Cross section ratio and angular distributions of the reaction p + d -> 3He + eta at 48.8 MeV and 59.8 MeV excess energy
We present new data for angular distributions and on the cross section ratio
of the p + d -> 3He + eta reaction at excess energies of Q = 48.8 MeV and Q =
59.8 MeV. The data have been obtained at the WASA-at-COSY experiment
(Forschungszentrum J\"ulich) using a proton beam and a deuterium pellet target.
While the shape of obtained angular distributions show only a slow variation
with the energy, the new results indicate a distinct and unexpected total cross
section fluctuation between Q = 20 MeV and Q = 60 MeV, which might indicate the
variation of the production mechanism within this energy interval.Comment: 9 pages, 9 figure
Neutron-Proton Scattering in the Context of the (2380) Resonance
New data on quasifree polarized neutron-proton scattering, in the region of
the recently observed resonance structure, have been obtained by
exclusive and kinematically complete high-statistics measurements with WASA at
COSY. This paper details the determination of the beam polarization, checks of
the quasifree character of the scattering process, on all obtained
angular distributions and on the new partial-wave analysis, which includes the
new data producing a resonance pole in the - coupled partial
waves at () MeV -- in accordance with the dibaryon
resonance hypothesis. The effect of the new partial-wave solution on the
description of total and differential cross section data as well as specific
combinations of spin-correlation and spin-transfer observables available from
COSY-ANKE measurements at = 2.27 GeV is discussed
Search for a dark photon in the decay
The presently world largest data sample of pi0 --> gamma e+e- decays
containing nearly 5E5 events was collected using the WASA detector at COSY. A
search for a dark photon U produced in the pi0 --> gamma U --> gamma e+e- decay
from the pp-->pp\pi^0 reaction was carried out. An upper limit on the square of
the U-gamma mixing strength parameter epsilon^2 of 5e-6 at 90% CL was obtained
for the mass range 20 MeV <M_U< 100 MeV. This result together with other recent
experimental limits significantly reduces the M_U vs. \epsilon^2 parameter
space preferred by the measured value of the muon anomalous magnetic moment.Comment: 16 pages, 8 figures; improved analysis extending the exclusion region
to 20 MeV<M_U< 100 MeV; implemented changes requested by referee
Evidence for a New Resonance from Polarized Neutron-Proton Scattering
Exclusive and kinematically complete high-statistics measurements of
quasifree polarized scattering have been performed in the energy
region of the narrow resonance structure with , 2380 MeV/ and 70 MeV observed recently in the
double-pionic fusion channels and .
The experiment was carried out with the WASA detector setup at COSY having a
polarized deuteron beam impinged on the hydrogen pellet target and utilizing
the quasifree process . That way the
analyzing power was measured over a large angular range. The obtained
angular distributions deviate systematically from the current SAID SP07
NN partial-wave solution. Incorporating the new data into the SAID
analysis produces a pole in the waves as expected from the
resonance hypothesis
ABC Effect and Resonance Structure in the Double-Pionic Fusion to He
Exclusive and kinematically complete measurements of the double pionic fusion
to He have been performed in the energy region of the so-called ABC effect,
which denotes a pronounced low-mass enhancement in the -invariant mass
spectrum. The experiments were carried out with the WASA detector setup at
COSY. Similar to the observations in the basic reaction
and in the He reaction, the data reveal a correlation
between the ABC effect and a resonance-like energy dependence in the total
cross section. Differential cross sections are well described by the hypothesis
of resonance formation during the reaction process in addition to the
conventional -channel mechanism. The deduced resonance
width can be understood from collision broadening due to Fermi motion of the
nucleons in initial and final nuclei
- …