L. De Cruz

Kaon photoproduction from the deuteron in a Regge-plus-resonance approach

Abstract We present a Regge-inspired effective-Lagrangian framework for kaon photoproduction from the deuteron. Quasi-free kaon production is investigated using the Regge-plus-resonance (RPR) elementary operator within the relativistic plane-wave impulse approximation. The RPR model was developed to describe photoinduced and electroinduced charged-kaon production off protons. We show how this elementary operator can be transformed in order to account for the production of neutral kaons from both protons and neutrons. The model results for kaon photoproduction from the deuteron compare favourably to the H 2 ( γ , K ) Y N data published to date.

Bayesian model selection for electromagnetic kaon production on the nucleon

Abstract We present the results of a Bayesian analysis of a Regge model to describe the background contribution for K + Λ and K + Σ 0 photoproduction. The model is based on the exchange of K + ( 494 ) and K * + ( 892 ) trajectories in the t-channel. We utilise the Bayesian evidence Z to determine the best model variant for each channel. The Bayesian evidence integrals were calculated using the Nested Sampling algorithm. For different prior widths, we find decisive Bayesian evidence ( Δ ln Z ≈ 24 ) for a K + Λ photoproduction Regge model with a positive vector coupling and a negative tensor coupling constant for the K * + ( 892 ) trajectory, and a rotating phase factor for both trajectories. Using the χ 2 minimisation method, one could not draw this conclusion from the same dataset. For the K + Σ 0 photoproduction Regge model, on the other hand, the difference between the evidence integrals is insufficient to pinpoint one model variant.

Regge‐plus‐resonance predictions for neutral‐kaon photoproduction from the deuteron

We present a Regge‐inspired effective‐Lagrangian framework for neutral‐kaon photo‐production from the deuteron. Quasi‐free kaon production is investigated using the Regge‐plus‐resonance elementary operator within the relativistic plane‐wave impulse approximation. The Regge‐plus‐resonance model was developed to describe photoinduced and electroinduced charged‐kaon production off protons. We show how this elementary operator can be transformed to account for the production of neutral kaons from both protons and neutrons. Our results compare favourably to the sole 2H(γ,K0)YN dataset published to date.

BAYESIAN MODEL SELECTION FOR ELECTROMAGNETIC KAON PRODUCTION ON THE NUCLEON

We present the results of a Bayesian analysis of a Regge model for K+Λ photoproduction. The model is based on the exchange of K+(494) and K*+(892) trajectories in the t-channel. For different prior widths, we find decisive Bayesian evidence (Δ ln Ƶ ≈ 24) for a K+Λ photoproduction Regge model with a positive vector coupling and a negative tensor coupling constant for the K*+(892) trajectory, and a rotating phase factor for both trajectories. Using the χ2 minimization method, one could not draw this conclusion from the same dataset.

The Regge-plus-resonance model for kaon production on the proton and the neutron

The Regge-plus-resonance (RPR) framework for kaon photoproduction on the proton and the neutron is an economical single-channel model with very few parameters. Not only does the RPR model allow one to extract resonance information from the data, it has predictive power. As an example we show that the RPR model makes fair predictions for the p(e, e′ K+)Λ and the n(γ, K+)Σ− observables starting from amplitudes optimized for the description of p(γ, K+)Λ and p(γ, K+)Σ0 respectively.

Creating the conditions of anomalous self‐diffusion in a liquid with molecular dynamics

We propose a computational method to simulate non‐Gaussian self‐diffusion in a simple liquid. The method is based on nonequilibrium molecular dynamics (NEMD).

Measurement of K{sup -}p radiative capture to gammaLAMBDA and gammaSIGMA{sup 0} for p{sub K}{sup -} between 514 and 750 MeV/c

Differential cross sections for K{sup -} radiative capture in flight on the proton, leading to the gammaLAMBDA and gammaSIGMA{sup 0} final states, have been measured at eight K{sup -} momenta between 514 and 750 MeV/c. The data were obtained with the Crystal Ball multiphoton spectrometer installed at the separated K/pi beam line C6 of the BNL Alternating Gradient Synchrotron. The results substantially improve the existing experimental data available for studying radiative decays of excited hyperon states. An exploratory theoretical analysis is performed within the Regge-plus-resonance approach. According to this analysis, the gammaSIGMA{sup 0} final state is dominated by hyperon-resonance exchange and hints at an important role for a resonance in the mass region of 1700 MeV. In the gammaLAMBDA final state, in contrast, the resonant contributions account for only half the strength, and the data suggest the importance of a resonance in the mass region of 1550 MeV.

Measurement ofK−pradiative capture toγΛandγΣ0forpK−between 514 and 750 MeV/c

Differential cross sections for K ― radiative capture in flight on the proton, leading to the γA and γΣ 0 final states, have been measured at eight K ― momenta between 514 and 750 MeV/c. The data were obtained with the Crystal Ball multiphoton spectrometer installed at the separated K/π beam line C6 of the BNL Alternating Gradient Synchrotron. The results substantially improve the existing experimental data available for studying radiative decays of excited hyperon states. An exploratory theoretical analysis is performed within the Regge-plus-resonance approach. According to this analysis, the γΣ 0 final state is dominated by hyperon-resonance exchange and hints at an important role for a resonance in the mass region of 1700 MeV. In the γΛ final state, in contrast, the resonant contributions account for only half the strength, and the data suggest the importance of a resonance in the mass region of 1550 MeV.

Measurement of K-p radiative capture to γΛ and γΣ0 for pK- between 514 and 750 MeV/c

Differential cross sections for K ― radiative capture in flight on the proton, leading to the γA and γΣ 0 final states, have been measured at eight K ― momenta between 514 and 750 MeV/c. The data were obtained with the Crystal Ball multiphoton spectrometer installed at the separated K/π beam line C6 of the BNL Alternating Gradient Synchrotron. The results substantially improve the existing experimental data available for studying radiative decays of excited hyperon states. An exploratory theoretical analysis is performed within the Regge-plus-resonance approach. According to this analysis, the γΣ 0 final state is dominated by hyperon-resonance exchange and hints at an important role for a resonance in the mass region of 1700 MeV. In the γΛ final state, in contrast, the resonant contributions account for only half the strength, and the data suggest the importance of a resonance in the mass region of 1550 MeV.

Regge‐model predictions for K+Σ photoproduction from the nucleon

We present Regge‐model predictions for the p(λ, K+)Σ0 and n(λ, K+)Σ− differential cross sections and photon‐beam asymmetries in the resonance region. The reaction amplitude encompasses the exchange of K+(494) and K**+(892) Regge‐trajectories, introducing a mere three free parameters. These are fitted to the available p(λ, K+)Σ0 data beyond the resonance region. The n(λ, K+)Σ− amplitude is obtained from the p(λ, K+)Σ0 one through SU (2) isospin symmetry considerations.