Search results for "Functional analysis"

New evidence for a narrow state of mass 2.02 GeV/c2

1993

Abstract We report evidence for the existence of a narrow p p state with a mass of 2.02 GeV/c2 and a width of about 0.02 GeV/c2, produced centrally in π+p(π−p) interactions at 20(12) GeV/c in several final states, proceeding via baryon exchange mechanism, and that could be interpreted as a baryonium candidate. The data come from the analysis of WA56 experiment made at the CERN Ω spectrometer.

New states as observed by the Crystal Barrel experiment

1993

Abstract The Crystal Barrel Detector has been in operation since October 1989. Results on the analysis of the annihilation of protonium at rest into three pseudoscalars is presented. The π 0 π 0 π 0 final state confirms the existence of ƒ 2 (1520)→π 0 π 0 . In the ηη system of the π 0 ηη final state an isoscalar J PC = 0 ++ resonance with a mass of 1560 MeV/c 2 and a width of 245 MeV/c 2 is observed. The identification with ƒ 0 (1590) is doubtful since the ηη' decay is not observed with the corresponding strength. Our analysis yields an upper limit for the relative branching ratio BR(ƒ 0 (1560)→ηη') BR(ƒ 0 (1560)→ηη) .

Pion photoproduction on3He including final-state interaction

1991

Coherent π0 and π+ photoproduction and elastic and charge-exchange pion scattering on3He has ben calculated in a consistent model. Realistic three-body Faddeev wave functions have been used and full nonlocal DWIA results for pion photoproduction are obtained. Furthermore, two-step processes such as3He(γ, π0)3He(π0, π+)3H are included giving rise to unexpected large results. The comparison with experimental data is very good over a wide range of photon energies and nuclear momentum transfers. A long-time discrepancy between previous impulse-approximation calculations and experimental data has been removed.

Decay of a 19− isomeric state in Lu156

2018

A multiparticle spin-trap isomeric state having a half-life of 179(4) ns and lying 2601 keV above the yrast 10(+) state in Lu-156 has been discovered. The Lu-156 nuclei were produced by bombarding ...

Final State Three-Body Coulomb Effects in thePb208(B8,Be7p)Pb208Coulomb Breakup Reaction

2003

We present results of the first calculation of the double differential cross section for the 208Pb(8B,(7)Bep)208Pb Coulomb breakup reaction which treats the postdecay acceleration of the ejectiles within a genuine three-body approach. From this we conclude that, in order to minimize postdecay Coulomb acceleration effects, experiments should be performed at as small as possible scattering angles, not too low 7Be-p relative energies, and high incident energy.

Measurement of the e+e− → π+π− cross section between 600 and 900 MeV using initial state radiation

2020

Three-Body Analysis of Incoherent Photoproduction of η Mesons on the Deuteron near Threshold

2003

The importance of three-body dynamics in the ηnp system in elastic and inelastic η-deuteron scattering as well as coherent and incoherent η photo-production on the deuteron in the energy region from threshold up to 30 MeV above has been investigated. It is shown that a restriction to first order rescattering with respect to the NN- and ηN-final state interactions, i.e., restriction to rescattering in the two-body subsystems, does not give a sufficiently accurate approximation to the s-wave reaction amplitude and that higher order terms, as described by the three-body dynamics give very substantial contributions.

Measurement of σ(e+e−→π+π−) from threshold to 0.85 GeV2 using initial state radiation with the KLOE detector

2011

Measurement of σ(e+e−→π+π−) from threshold to 0.85 GeV2 using initial state radiation with the KLOE detector

Invisible width of the Z-boson and “secret” ν-ν interactions

1993

Abstract The width of the decay Z→ν ν ν ν in the presence of a possible nonstandard four-fermion ν-ν interaction is calculated. From the invisible width of the Z-boson measured at LEP the upper bound on the strength F of such an effective interaction has been obtained: F≲4×102GF. This bound is about three orders of magnitude lower than earlier existing particle physics bounds and it is comparable with an estimate that can be obtained from supernova neutrino data. The expression for the spectrum of leptons in the decays W→lν l ν ν is also presented.

T- and P-asymmetries in the (γ, π−) reaction on 13C and 15N

1995

Abstract A simultaneous theoretical analysis of the polarization observables for negative pion photoproduction off the 13 C and 15 N nuclei is performed. A sensitivity of the target and recoil asymmetries to different ingredients of the theory (the Fermi motion, the final state interaction and the nuclear model input) is investigated. The importance of the high (2 hω ) configurations in the nuclea ground states is shown.