Using a sample of
1.31
×
10
9
J
/
ψ
events collected with the BESIII detector, we perform a study of
J
/
ψ
→
γ
K
K
¯
η
′
.
X
(2370) is observed in the
K
K
¯
η
′
invariant-mass distribution with a ...statistical significance of
8.3
σ
. Its resonance parameters are measured to be
M
=
2341.6
±
6.5
(stat.)
±
5.7
(syst.)
MeV
/
c
2
and
Γ
=
117
±
10
(stat.)
±
8
(syst.)
MeV
. The product branching fractions for
J
/
ψ
→
γ
X
(
2370
)
,
X
(
2370
)
→
K
+
K
-
η
′
and
J
/
ψ
→
γ
X
(
2370
)
,
X
(
2370
)
→
K
S
0
K
S
0
η
′
are determined to be
(
1.79
±
0.23
(stat.)
±
0.65
(syst.)
)
×
10
-
5
and
(
1.18
±
0.32
(stat.)
±
0.39
(syst.)
)
×
10
-
5
, respectively. No evident signal for
X
(2120) is observed in the
K
K
¯
η
′
invariant-mass distribution. The upper limits for the product branching fractions of
B
(
J
/
ψ
→
γ
X
(
2120
)
→
γ
K
+
K
-
η
′
)
and
B
(
J
/
ψ
→
γ
X
(
2120
)
→
γ
K
S
0
K
S
0
η
′
)
are determined to be
1.49
×
10
-
5
and
6.38
×
10
-
6
at the 90% confidence level, respectively.
Determination of the number of ψ(3686) events at BESIII Ablikim, M.; An, F. F.; Baldini Ferroli, R. ...
Chinese Physics C, High Energy Physics and Nuclear Physics/Chinese physics C,
02/2018, Letnik:
42, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The numbers of psi(3686) events accumulated by the BESIII detector for the data taken during 2009 and 2012 are determined to be (107.0 +/- 0.8)x10(6) and (341.1 +/- 2.1)x10(6), respectively, by ...counting inclusive hadronic events, where the uncertainties are systematic and the statistical uncertainties are negligible. The number of events for the sample taken in 2009 is consistent with that of the previous measurement. The total number of psi(3686) events for the two data taking periods is (448.1 +/- 2.9) x 10(6).
Spin-averaged asymmetries in the azimuthal distributions of positive and negative hadrons produced in deep inelastic scattering were measured using the CERN SPS longitudinally polarised muon beam at ...160 GeV/c and a 6LiD target. The amplitudes of the three azimuthal modulations cosϕh, cos2ϕh and sinϕh were obtained binning the data separately in each of the relevant kinematic variables x, z or pTh and binning in a three-dimensional grid of these three variables. The amplitudes of the cosϕh and cos2ϕh modulations show strong kinematic dependencies both for positive and negative hadrons.
The COMPASS setup for physics with hadron beams Abbon, P.; Adolph, C.; Amoroso, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2015, Letnik:
779
Journal Article
Recenzirano
Odprti dostop
The main characteristics of the COMPASS experimental setup for physics with hadron beams are described. This setup was designed to perform exclusive measurements of processes with several charged ...and/or neutral particles in the final state. Making use of a large part of the apparatus that was previously built for spin structure studies with a muon beam, it also features a new target system as well as new or upgraded detectors. The hadron setup is able to operate at the high incident hadron flux available at CERN. It is characterised by large angular and momentum coverages, large and nearly flat acceptances, and good two and three-particle mass resolutions. In 2008 and 2009 it was successfully used with positive and negative hadron beams and with liquid hydrogen and solid nuclear targets. This paper describes the new and upgraded detectors and auxiliary equipment, outlines the reconstruction procedures used, and summarises the general performance of the setup.
The Collins and Sivers asymmetries for charged hadrons produced in deeply inelastic scattering on transversely polarised protons have been extracted from the data collected in 2007 with the CERN SPS ...muon beam tuned at 160 GeV/c. At large values of the Bjorken x variable non-zero Collins asymmetries are observed both for positive and negative hadrons while the Sivers asymmetry for positive hadrons is slightly positive over almost all the measured x range. These results strongly support the present theoretical interpretation of these asymmetries, in terms of leading-twist quark distribution and fragmentation functions.
Using 2.93 fb−1 of e+e− collision data collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, the first observation of the doubly Cabibbo-suppressed decay D+ → K+π+π−π0 is ...reported. After removing decays that contain narrow intermediate resonances, including D+ → K+η, D+ → K+ω, and D+ → K+ϕ, the branching fraction of the decay D+ → K+π+π−π0 is measured to be ( 1.13 ± 0.0 8stat ± 0.0 3syst) × 10−3. The ratio of branching fractions of D+ → K+π+π−π0 over D+ → K−π+π+π0 is found to be ( 1.81 ± 0.15 )%, which corresponds to ( 6.28 ± 0.52 ) tan4θC, where θC is the Cabibbo mixing angle. This ratio is significantly larger than the corresponding ratios for other doubly Cabibbo-suppressed decays. The asymmetry of the branching fractions of charge-conjugated decays D± → K±π±π∓π0 is also determined, and no evidence for C P violation is found. In addition, the first evidence for the D+ → K+ω decay, with a statistical significance of 3.3σ, is presented and the branching fraction is measured to be B (D+ → K+ω) = ( 5. 7−2.1 stat+2.5 ± 0.2syst ) × 10−5.
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