53 research outputs found
Search for the pentaquark via the reaction at 1.92 GeV/
The pentaquark baryon was searched for via the
reaction in a missing-mass resolution of 1.4 MeV/(FWHM) at J-PARC.
meson beams were incident on the liquid hydrogen target with the beam momentum
of 1.92 GeV/. No peak structure corresponding to the mass was
observed. The upper limit of the production cross section averaged over the
scattering angle of 2 to 15 in the laboratory frame was
obtained to be 0.26 b/sr in the mass region of 1.511.55 GeV/.The
upper limit of the decay width using the effective Lagrangian
approach was obtained to be 0.72 MeV/ and 3.1 MeV/ for
and , respectively.Comment: 5 pages, 3 figures, 1 tabl
Search for H hypernucleus by the Li reaction at = 1.2 GeV/
We have carried out an experiment to search for a neutron-rich hypernucleus,
H, by the Li() reaction at =1.2
GeV/. The obtained missing mass spectrum with an estimated energy resolution
of 3.2 MeV (FWHM) showed no peak structure corresponding to the H
hypernucleus neither below nor above the H particle decay
threshold. An upper limit of the production cross section for the bound
H hypernucleus was estimated to be 1.2 nb/sr at 90% confidence
level.Comment: 6 pages, 5 figures, published versio
Search for the pentaquark at J-PARC
We have been searching for the Θ^+ pentaquark via the π^−p→K^−X reaction at the J-PARC hadron facility. No peak structure was observed in the missing mass spectrum obtained at 1.92 GeV/c beam momentum. The upper limit for the production cross section averaged over the scattering angle from 2° to 15° in the laboratory frame was derived to be 0.26 μb/sr. In order to make a more stringent constraint we have also performed a measurement at 2.0 GeV/c. Present analysis status of this new data is reported
High-resolution search for the pentaquark via a pion-induced reaction at J-PARC
The pentaquark has been searched for via the
reaction with beam momenta of 1.92 and 2.01 GeV/ at J-PARC. A missing mass
resolution of 2 MeV (FWHM) was achieved but no sharp peak structure was
observed. The upper limits on the production cross section averaged over the
scattering angle from 2 to 15 in the laboratory frame were
found to be less than 0.28 b/sr at the 90\% confidence level for both the
1.92- and 2.01-GeV/ data. The systematic uncertainty of the upper limits was
controlled within 10\%. Constraints on the decay width were also
evaluated with a theoretical calculation using effective Lagrangian. The
present result implies that the width should be less than 0.36 and 1.9 MeV for
the spin-parity of and , respectively.Comment: 12 pages, 9 figures; published versio
Beam and SKS spectrometers at the K1.8 beam line
High-resolution spectrometers for both incident beams and scattered particles have been constructed at the K1.8 beam line of the Hadron Experimental Facility at J-PARC. A point-to-point optics is realized between the entrance and exit of QQDQQ magnets for the beam spectrometer. Fine-pitch wire chamber trackers and hodoscope counters are installed in the beam spectrometer to accept a high rate beam up to 107 Hz. The superconducting kaon spectrometer for scattered particles was transferred from KEK with modifications to the cryogenic system and detectors. A missing-mass resolution of 1.9 ± 0.1 MeV/c2 (FWHM) was achieved for the ∑ peaks of (π±, K+) reactions on a proton target in the first physics run of E19 in 2010
Study on Λ6H hypernucleus by the (π−, K+) reaction at J-PARC
We carried out an experiment to produce the neutron-rich hypernucleus 6H via the (¼ − , K + ) reaction on 6 Li target at the pion beam momentum of 1.2 GeV/c (J-PARC E10). In order to calibrate the scale of the missing-mass or of thebinding energy of the hypernucleus, we also measured the 12 C(¼ + , K + ) 12 ¤ C, p(¼ − , K + )§ − and p(¼ + , K + )§ + reactions. The experiment was performed at the J-PARC Hadron Hall K1.8 beam line in December 2012 and January 2013. The overall collected data sample corresponds to an integrated beam intensity of 1.65× 10 12 pions
Hadron physics programs at J-PARC
The J-PARC Hadron Facility is designed as a multipurpose experimental facility for a wide range of particle and nuclear physics programs, aiming to provide the world highest intensity secondary beams. Currently three secondary beam lines; K1.8, K1.8BR and KL together with the test beam line named K1.1BR come into operation. Various experimental programs are proposed at each beam line and some of them have been performed so far. As the first experiment at the J-PARC Hadron Facility, the Θ+ pentaquark was searched for via the pion-induced hadronic reaction in the autumn of 2010. Also experimental programs to search for new hadronic states such as K−pp have started to perform a physics run. The current status and near future programs are introduced
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