Search results for "form factor [N(1535)]"
showing 10 items of 205 documents
Pion Form Factor Measurement and ISR at BESIII
2017
Abstract At BESIII, we measured the cross section of 900 MeV/c2 with a 2.93 fb−1 data set taken at the center-of-mass energy 3.773 GeV. The initial state radiation technique is used, and the total systematic uncertainty is estimated to be 0.9%. The squared form factor | F π | 2 is extracted, and comparisons are made with results from both KLOE and BaBar. The two-pion contribution to the hadronic vacuum polarization contribution to ( g − 2 ) μ is calculated to be a μ π π , LO ( 600 − 900 MeV / c 2 ) = ( 368.2 ± 2.5 s t a t . ± 3.3 s y s t . ) ⋅ 10 − 10 .
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…
Charge Form Factor of the Neutron at Low Momentum Transfer from theH→2(e→,e′n)H1Reaction
2008
We report new measurements of the neutron charge form factor at low momentum transfer using quasielastic electrodisintegration of the deuteron. Longitudinally polarized electrons at an energy of 850 MeV were scattered from an isotopically pure, highly polarized deuterium gas target. The scattered electrons and coincident neutrons were measured by the Bates Large Acceptance Spectrometer Toroid (BLAST) detector. The neutron form factor ratio ${G}_{E}^{n}/{G}_{M}^{n}$ was extracted from the beam-target vector asymmetry ${A}_{\mathrm{ed}}^{V}$ at four-momentum transfers ${Q}^{2}=0.14$, 0.20, 0.29, and $0.42\text{ }\text{ }(\mathrm{GeV}/c{)}^{2}$.
Measuring the Chiralities of Weak b → c(u) Transitions in Exclusive B Meson Decays
1989
I discuss possibilities to measure the chirality of the weak b → c(u) transitions in exclusive bottom meson decays in (i) the exclusive semileptonic decay process B → D* + 1 + ν1 and (ii) in the exclusive nonleptonic decays of bottom mesons to baryon-antibaryon pairs.
Reinterpretation of Classic Proton Charge Form Factor Measurements
2020
In 1963, a proton radius of $0.805(11)~\mathrm{fm}$ was extracted from electron scattering data and this classic value has been used in the standard dipole parameterization of the form factor. In trying to reproduce this classic result, we discovered that there was a sign error in the original analysis and that the authors should have found a value of $0.851(19)~\mathrm{fm}$. We additionally made use of modern computing power to find a robust function for extracting the radius using this 1963 data's spacing and uncertainty. This optimal function, the Pad\'{e} $(0,1)$ approximant, also gives a result which is consistent with the modern high precision proton radius extractions.
Measurement of the Charge-Averaged Elastic Lepton-Proton Scattering Cross Section by the OLYMPUS Experiment
2020
Physical review letters 126(16), 162501 (1-6) (2021). doi:10.1103/PhysRevLett.126.162501
Measurement of proton electromagnetic form factors in the time-like region using initial state radiation at BESIII
2021
Physics letters / B 817, 136328 (2021). doi:10.1016/j.physletb.2021.136328
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.
Measurement of the decay rate and form factor parameter in the decay KL→e+e−γ
1999
Abstract The decay rate of the neutral K meson KL→e+e−γ has been measured with the NA48 detector at the CERN SPS. A total of 6864 events has been observed with an estimated background of 10 events. The branching ratio is Γ(KL→e+e−γ)/Γ(KL→all) = (1.06±0.02stat±0.02sys±0.04calc)×10−5. The parameter α K ∗ describing the relative strength of the two contributing amplitudes to this decay through intermediate pseudoscalar or vector mesons was measured to be α K ∗ =−0.36±0.06stat±0.02sys.
Measurement of the π0, η, η′ Transition Form Factors at BABAR
2013
Abstract Measurements of the transition form factors of the pseudoscalar mesons π 0 , η, η ′ have been carried out by the BABAR collaboration at the SLAC B-factory PEP-II. The form factors F ( Q 2 ) were measured in two-photon processes covering the kinematic range 4 GeV 2 Q 2 40 GeV 2 . For the π 0 form factor, results are significantly higher than predicted by Brodsky and Lepage assuming an asymptotic distribution amplitude. Data also suggest that the asymptotic regime of QCD is reached only at relatively high Q 2 . We also report on measurements of the η and η ′ transition form factors, which happen to feature a significantly different Q 2 behaviour than the one of the neutral pion.