Staging History Happé, Peter; Hüsken, Wim
2021, Letnik:
16
eBook
Staging History unites essays by nine specialists in the field of late medieval and early Renaissance drama. Their focus is on English, Dutch and Humanist German drama, as well as on a modern Swiss ...adaptation of Shakespeare's Henry V.
Exclusive measurements of the quasi-free pn→ppπ− and pp→ppπ0 reactions have been performed by means of pd collisions at Tp=1.2 GeV using the WASA detector setup at COSY. Total and differential cross ...sections have been obtained covering the energy region Tp=0.95–1.3 GeV (s=2.3–2.46 GeV), which includes the regions of Δ(1232), N⁎(1440) and d⁎(2380) resonance excitations. From these measurements the isoscalar single-pion production has been extracted, for which data existed so far only below Tp=1 GeV. We observe a substantial increase of this cross section around 1 GeV, which can be related to the Roper resonance N⁎(1440), the strength of which shows up isolated from the Δ resonance in the isoscalar (Nπ)I=0 invariant-mass spectrum. No evidence for a decay of the dibaryon resonance d⁎(2380) into the isoscalar (NNπ)I=0 channel is found. An upper limit of 180 μb (90% C.L.) corresponding to a branching ratio of 9% has been deduced.
New data on both total and differential cross sections of the production of η mesons in proton–deuteron fusion to He3η in the excess energy region 13.6MeV≤Qη≤80.9MeV are presented. These data have ...been obtained with the WASA-at-COSY detector setup located at the Forschungszentrum Jülich, using a proton beam at 15 different beam momenta between pp=1.60GeV/c and pp=1.74GeV/c. While significant structure of the total cross section is observed in the energy region 20MeV≲Qη≲60MeV, a previously reported sharp variation around Qη≈50MeV cannot be confirmed. Angular distributions show the typical forward-peaking that was noted earlier. For the first time, it is possible to study the development of these angular distributions with rising excess energy over a wide interval.
A
bstract
By using 6.32 fb
−
1
of data collected with the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV, we perform an amplitude analysis of the decay
$$ {D}_s^{+}\to ...{K}_S^0{\pi}^{+}{\pi}^0 $$
D
s
+
→
K
S
0
π
+
π
0
and determine the relative fractions and phase differences of different intermediate processes, which include
$$ {K}_S^0\rho $$
K
S
0
ρ
(770)
+
,
$$ {K}_S^0\rho $$
K
S
0
ρ
(1450)
+
,
K
*
(892)
0
π
+
,
K
*
(892)
+
π
0
, and
K
*
(1410)
0
π
+
. With the detection efficiency based on the amplitude analysis results, the absolute branching fraction is measured to be
$$ \mathrm{\mathcal{B}}\left({D}_s^{+}\to {K}_S^0{\pi}^{+}\pi 0\right)=\left(5.43\pm {0.30}_{\mathrm{stat}}\pm {0.15}_{\mathrm{syst}}\right)\times {10}^{-3} $$
ℬ
D
s
+
→
K
S
0
π
+
π
0
=
5.43
±
0.30
stat
±
0.15
syst
×
10
−
3
.
A
bstract
The decays
D
→
K
−
π
+
π
+
π
−
and
D
→
K
−
π
+
π
0
are studied in a sample of quantum-correlated
$$ D\overline{D} $$
D
D
¯
pairs produced through the process
e
+
e
−
→
ψ
(3770) →
$$ ...D\overline{D} $$
D
D
¯
, exploiting a data set collected by the BESIII experiment that corresponds to an integrated luminosity of 2.93 fb
−
1
. Here
D
indicates a quantum superposition of a
D
0
and a
$$ {\overline{D}}^0 $$
D
¯
0
meson. By reconstructing one neutral charm meson in a signal decay, and the other in the same or a different final state, observables are measured that contain information on the coherence factors and average strong-phase differences of each of the signal modes. These parameters are critical inputs in the measurement of the angle
γ
of the Unitarity Triangle in
B
−
→
DK
−
decays at the LHCb and Belle II experiments. The coherence factors are determined to be
R
K
3
π
=
$$ {0.52}_{-0.10}^{+0.12} $$
0.52
−
0.10
+
0.12
and
$$ {R}_{K{\pi \pi}^0} $$
R
K
ππ
0
= 0
.
78 ± 0
.
04, with values for the average strong-phase differences that are
$$ {\delta}_D^{K3\pi }=\left({167}_{-19}^{+31}\right){}^{\circ} $$
δ
D
K
3
π
=
167
−
19
+
31
°
and
$$ {\delta}_D^{K{\pi \pi}^0}=\left({196}_{-15}^{+14}\right){}^{\circ} $$
δ
D
K
ππ
0
=
196
−
15
+
14
°
, where the uncertainties include both statistical and systematic contributions. The analysis is re-performed in four bins of the phase-space of the
D
→
K
−
π
+
π
+
π
−
to yield results that will allow for a more sensitive measurement of
γ
with this mode, to which the BESIII inputs will contribute an uncertainty of around 6°.
We report on the search for the rare decay η→π0e+e− which is of interest to study C violation in the electromagnetic interaction which would indicate contributions from physics beyond the Standard ...Model, since the allowed decay via a two-photon intermediate state is strongly suppressed. The experiment has been performed using the WASA-at-COSY installation, located at the COSY accelerator of the Forschungszentrum Jülich, Germany. In total 3×107 events of the reaction pd→3Heη have been recorded at an excess energy of Q=59.8MeV. Based on this data set the C parity violating decay η→π0γ⁎→π0e+e− via a single-photon intermediate state has been searched for, resulting in new upper limits of Γ(η→π0e+e−)/Γ(η→π+π−π0)<3.28×10−5 and Γ(η→π0e+e−)/Γ(η→all)<7.5×10−6 (CL=90%), respectively.
This letter reports a first quantitative analysis of the contribution of higher partial waves in the charge symmetry breaking reaction dd→4Heπ0 using the WASA-at-COSY detector setup at an excess ...energy of Q=60MeV. The determined differential cross section can be parametrized as dσ/dΩ=a+bcos2θ⁎, where θ⁎ is the production angle of the pion in the center-of-mass coordinate system, and the results for the parameters are a=(1.55±0.46(stat)+0.32−0.8(syst))pb/sr and b=(13.1±2.1(stat)−2.7+1.0(syst))pb/sr. The data are compatible with vanishing p-waves and a sizable d-wave contribution. This finding should strongly constrain the contribution of the Δ isobar to the dd→4Heπ0 reaction and is, therefore, crucial for a quantitative understanding of quark mass effects in nuclear production reactions.
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