Model discrimination in pseudoscalar-meson photoproduction

Abstract

To learn about a physical system of interest, experimental results must be able to discriminate among models. We introduce a geometrical measure to quantify the distance between models for pseudoscalar-meson photoproduction in amplitude space. Experimental observables, with finite accuracy, map to probability distributions in amplitude space, and the characteristic width scale of such distributions needs to be smaller than the distance between models if the observable data are going to be useful. We therefore also introduce a method for evaluating probability distributions in amplitude space that arise as a result of one or more measurements, and show how one can use this to determine what further measurements are going to be necessary to be able to discriminate among models

Structure of pion photoproduction amplitudes

“…At this stage, we cannot conclude if the observed differences in the sum rules between the various models are coming from the model dependence, or rather by the data uncertainties in the low energy region. The amplitudes of the available models are not fully constrained, since a complete set of observables is not yet available [55][56][57][58]. On can expect that if double polarization measurements were included the low-energy models could change as shown for example in Ref.…”

The impact of $K^{+}\Lambda$ K + Λ photoproduction on the resonance spectrum

“…See also Ref. [25] in this context in which the question is addressed of how precise data have to be to discriminate between models.…”

Beam-target helicity asymmetry E in K0Λ and K0Σ0Ho1, Schumacher2, D’Angelo3 et al. 2018Phys. Rev. C12040View full textAdd to dashboardCite

“…Polarization observables related to the spins of the beam photons, target, and recoiling baryons are also needed. Photoproduction of pseudoscalar mesons is governed by four complex amplitudes that lead to an interaction cross sections and 15 spin observables [17][18][19][20][21][22][23]. A mathematically complete experiment would require data, with negligible uncertainties, on a minimum of eight wellchosen observables at each center-of mass (c.m.)…”

“…In practice, with realistically achievable uncertainties, measurements of many more are needed to select between competing partial wave solutions, and even knowledge of the sign of an asymmetry can provide valuable discrimination [22]. Furthermore, avoiding ambiguities in PWA solutions requires measurements of observables from each spin configuration of the three combinations of beamtarget, target-recoil and beam-recoil polarization [22,23].…”