Search results for "Strangeness"
showing 10 items of 118 documents
Prospects for hypernuclear physics at Mainz: From KAOS@MAMI to PANDA@FAIR
2013
Abstract At the Mainz Microtron hypernuclei are produced by ( e , e ′ K ) reactions. A dedicated kaon spectrometer located at 0° with respect to the electron beam is used to detect kaons emitted in forward direction thus tagging events involving strangeness production. By measuring the momenta of pions from two body weak decays using high resolution magnetic spectrometers one gains direct access to the ground state masses of the produced hyperfragments. At FAIR the PANDA Collaboration intends to produce double-hypernuclei by numbers with an antiproton beam and study their high resolution γ -spectroscopy thus providing for the first time precise information on the level structure of these nu…
Nucleon Vector Strangeness Form Factors: Multi-pion Continuum and the OZI Rule
1997
We estimate the 3 \pi continuum contribution to the nucleon strange quark vector current form factors, including the effect of a 3 \pi \rho \pi resonance. We find the magnitude of this OZI-violating contribution to be comparable to that of typical OZI-allowed contributions. We also study the isoscalar electromagnetic form factors, and find that the presence of a \rho \pi resonance in the multi-pion continuum may generate an appreciable contribution.
Pseudorapidity and transverse-momentum distributions of charged particles in proton–proton collisions at s=13 TeV
2016
The pseudorapidity (η) and transverse-momentum (pT) distributions of charged particles produced in proton-proton collisions are measured at the centre-of-mass energy s√ = 13 TeV. The pseudorapidity distribution in |η|< 1.8 is reported for inelastic events and for events with at least one charged particle in | η|< 1. The pseudorapidity density of charged particles produced in the pseudorapidity region |η|< 0.5 is 5.31 ± 0.18 and 6.46 ± 0.19 for the two event classes, respectively. The transverse-momentum distribution of charged particles is measured in the range 0.15 < pT < 20 GeV/c and |η|< 0.8 for events with at least one charged particle in |η|< 1. The correlation between transverse momen…
Chiral dynamics in theγp→π0ηpandγp→π0K0Σ+reactions
2006
Using a chiral unitary approach for meson-baryon scattering in the strangeness zero sector, where the ${N}^{*}(1535){S}_{11}$ resonance is dynamically generated, we study the reactions $\ensuremath{\gamma}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}\ensuremath{\eta}p$ and $\ensuremath{\gamma}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{K}^{0}{\ensuremath{\Sigma}}^{+}$ at photon energies at which the final states are produced close to threshold. Among several reaction mechanisms, we find the most important is the excitation of the ${\ensuremath{\Delta}}^{*}(1700){D}_{33}$ state, which subsequently decays into a pseudoscalar meson and a baryon belonging to the $\ensuremath{\Delta}(1232)…
Primakoff scattering for polarized photons or polarized protons
1993
Abstract We present a way to measure the axial coupling of the proton for the neutral strangeness current in coherent π0 production induced by photon-proton scattering. By means of the γ−Z−π0 triangle anomaly, the parity violating asymmetries for polarized photon or polarized proton Primakoff effect filter the couplings so as to leave the proton axial coupling only. We calculate the relevant observables induced by the electroweak interference and give results for regions of energy and Q2 of possible experimental interest. The polarized proton asymmetry is predicted to be 10−6-10−5 when Q2 ∼ 0.1−0.5 GeV2.
Strange nucleon form-factors
2017
Abstract A broad program measuring parity-violation in electron-nuclear scattering has now provided a large set of precision data on the weak-neutral-current form-factors of the proton. Under comparison with well-measured electromagnetic nucleon form-factors, these measurements reveal the role of the strange quark sea on the low-energy interactions of the proton through the strange-quark-flavor vector form-factors. This review will describe the experimental program and the implications of the global data for the strange-quark vector form-factors. We present here a new fit to the world data.
Status of J-PARC E07: Systematic study of double strangeness nuclei with hybrid emulsion method
2019
J-PARC E07 is the most complex emulsion experiment to date investigating double hypernuclei with a hybrid emulsion method. This experiment aims to detect 104 Ξ− stop events, ten times more events than the past experiments. Thus, an unequivocal identification of several new double hypernuclei is expected. The beam exposure has been completed at the K1.8 beam line of the J-PARC hadron facility in June 2017. The photographic development of all emulsion sheets has also been completed in February 2018. The emulsion sheets are presently being analyzed with dedicated optical microscopes. Current statistics is comparable to that of E373 and so far 10 events of 3-vertices topology have been detected…
Parity-violating electron scattering at MAMI
2003
A measurement of the parity-violating asymmetry in elastic scattering of polarized electrons on protons is currently running within the A4 Collaboration at the MAMI facility in Mainz. The aim is to reveal the contribution of strange quarks to the form factors of the nucleon at a Q 2 = 0.23 GeV2. The expected asymmetry without strangeness is around 5.4 × 10−6. After 600 hours of asymmetry data taking, an accuracy of 1 × 10−6 has been achieved.
Status of the J-PARC E07, Systematic Study of Double Strangeness Nuclei with the Hybrid Emulsion Method
2019
The current status of the J-PARC E07 experiment and two typical events, a _ΛΛBe hypernuclear event named “MINO” and \(_{\Xi }^{15}\text{C}\) hypernuclear event named “IBUKI”, are presented. J-PARC E07 is the most complex emulsion experiment so far to investigate double hypernuclei. The physics run at the K1.8 beam line in the J-PARC hadron facility and photographic development of all emulsion sheets have been completed. The emulsion sheets are presently being analyzed with dedicated optical microscopes. Current statistics are estimated to be about twice that of KEK-PS E373. Quantitative data on ΔB_ΛΛ of double Λ hypernucleus and \(B_{\Xi ^{ - }}\) of Ξ hypernucleus are being accumulated suc…
Final states with strangeness from Crystal Barrel and Asterix
1993
Abstract We discuss φ production in p p annihilation at rest from the Asterix and Crystal Barrel experiments and compare the branching ratios to similar final states without strangeness. The ωπ 0 φπ 0 production ratio is unexpectedly low. In the search for new states, the φπ0 mass spectrum shows no evidence for a resonance in the 1450 MeV/c2 mass range but the K☆K0π0 Dalitz plot shows interesting structure.