Search results for "form factor [N(1535)]"
showing 10 items of 205 documents
Physical observables in the decay Λb→Λc(→Λ+π)+τ−+ν̄τ
2015
We analyze the tauonic semileptonic baryon decays [Formula: see text] with particular emphasis on the lepton helicity flip contributions which vanish for zero lepton masses. We calculate the total rate, differential decay distributions, the longitudinal and transverse polarization components of the [Formula: see text] and the [Formula: see text], and the lepton-side forward-backward asymmetries. We use the covariant confined quark model to provide numerical results on these observables.
Muon capture in11B
1971
In this paper the partial-capture rates of muons in11B going to11Be(g.s.) and11Be (320 keV), as well as the hyperfine effect in the transition to11Be*, are studied. Comparing these results with the beta-decay of11Be and the electromagnetic transition11Be* →11Be, we can derive some conclusions on the nuclear structure of the bound states of11Be. We also discuss some possible experiences which can give information on the pseudoscalar form factor in weak interactions.
Hyperon Semileptonic Decays and CKM Unitarity
2005
We perform a new numerical analysis of hyperon semileptonic decays emphasizing the systematic uncertainties. The poor understanding of SU(3) symmetry breaking effects at second order in the vector form factor translates into a large error of |V(us)|. Using our determination |V(us)| = 0.226 +/- 0.005 together with those coming from other sources we test the unitarity of the CKM matrix.
About entangled networks of worm-like micelles: a rejected hypothesis
1996
We report new results from small-angle neutron scattering on d(1 2)-cyclohexane/lecithin/water micellar solutions performed as a function of the water content (w(o)), temperature (T) and dispersed phase volume fraction (phi). The data from dilute samples are interpretable in terms of the existence of giant cylindrical reverse micelles and are well fit with a core-shell model (that provides the micelle structure and dimensions) with values of 28 and 45 Angstrom for the inner core and the outer shell radii, almost independent on temperature and concentration. Such a result could appear consistent with the current idea that worm-like micelles are living polymers. On the contrary, the appearanc…
Relativistic corrections to the elastic electron scattering fromPb208
1976
In the present work we have calculated the differential cross sections for the elastic electron scattering from $sup 208$Pb using the charge distributions resulting from various corrections. The point proton and neutron mass distributions have been calculated from the spherical wave functions for $sup 208$Pb obtained by Kolb et al. The relativistic correction to the nuclear charge distribution coming from the electromagnetic structure of the nucleon has been accomplished by assuming a linear superposition of Gaussian shapes for the proton and the neutron charge form factor. Results of this calculation are quite similar to an earlier calculation by Bertozzi et al., who have used a different …
The decays K→πl+l− beyond leading order in the chiral expansion
1998
We present a model-independent analysis of K+→π+l+l− and KS→π0l+l− decays, including K→3π unitarity corrections and a general decomposition of the dispersive amplitude. From the existing data on K+→π+e+e− we predict the ratio R = B(K+→π+μ+μ−)/B(K+→π+e+e−) to be larger than 0.23, in slight disagreement with the recent measurement R = 0.167±0.036. Consequences for the K±→π±e+e− charge asymmetries and for the KL→π0e+e− mode are also discussed.
Electromagnetic Processes and Interactions
2011
The electron, the muon, and their neutrinos are important tools in testing the structure of the fundamental electromagnetic and weak interactions. On the other hand, if these interactions are known, they serve as ideal probes for the internal structure of complex hadronic targets such as nucleons and nuclei. Although electroweak interactions should in fact be discussed as a whole and on the same footing, purely electromagnetic interactions play a distinctive role, for obvious experimental reasons: At low and intermediate energies the effective electromagnetic coupling is larger by many orders of magnitude than the weak couplings, so that electromagnetic processes are measurable to much high…
The End Point Tagger physics program at A2@MAMI
2017
The A2-Collaboration uses a beam of real photons from the tagged photon facility at the electron accelerator MAMI in Mainz, Germany, to study photo-produced mesons. A new tagging device allows access to the higher photon beam energy range of 1.4 to 1.6 GeV. A large dataset containing more than 6 million η ′ and roughly 29 million ω decays has been obtained. Analyses are ongoing, including a study of the cusp effect and Dalitz plot in η ′ → ηπ 0 π 0 , giving insight to the π π scattering length and the structure of the ηππ system, as well as the measurement of the electromagnetic transition form factor in η ′ → e + e − γ , a cross section measurement of γ p → 3 π 0 , and branching ratio anal…
TheN-? transition form factor and anomalous?-decays into octet-decuplet baryon-antibaryon Pairs
1987
We develop a Generalized-Vector-Meson Dominance Model (GVDM) for the invariantN-Δ transition form factors which incorporates the correct largeq2 power behaviour of QCD and describes the available lowq2 space-like data. We then use this GVDM transition form factor in the time-like region to calculate theSU (3) singlet and octet contributions to Ψ-decays into octet-decuplet baryon-antibaryon pairs. The results are compared to recent data on Ψ-decays into octet-decuplet baryon-antibaryon pairs.
Space-like transition form factors from BESIII
2018
Abstract The anomalous magnetic momentum of muon, a μ , has been measured in experiment and calculated in theory with a precision up to ∼0.5 ppm. But there is a long standing 3 to 4 standard deviations between these two accurate values. The dominant contribution to the uncertainty in the theoretical calculation comes from the hadroninc contribution, including contributions from the hadronic vacuum polarization and the hadronic light-by-light. The meson transition form factors measured in two photon process at BESIII can be used as input or constrain for the calculation of the hadronic light-by-light contribution to a μ . Recent experimental activities, including the measurements of the tran…