arXiv subjects

Paolo Pedroni

Publications and source records attributed to Paolo Pedroni.

4 recordsLinked to original sources

arXiv2023

The Gerasimov-Drell-Hearn sum-rule with nuclear targets

Hadron properties are modified when the hadron is embedded in a nuclear medium. Here we discuss the Gerasimov-Drell-Hearn, GDH, sum rule for polarised photoproduction from a polarised nucleon within a polarised nuclear target. Strong enhancement is expected with the suppression of the proton and nucleon resonance masses and enhancement of the proton's anomalous magnetic moment in medium. This could be tested in polarised photoproduction experiments with interesting targets being polarised deuterons, $^3$He, $^6$Li and $^7$Li. The largest contribution to the GDH sum rule comes from the $Δ$ resonance excitation. In existing data with polarised deuterons and $^3$He the $Δ$ excitation is shifted to slightly lower energy when compared to model predictions where the $Δ$ is treated with its free mass.

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arXiv2020

$K^+Λ$(1405) photoproduction at the BGO-OD experiment

Since the discovery of the $Λ(1405)$, it remains poorly described by conventional constituent quark models, and it is a candidate for having an "exotic" meson-baryon or "penta-quark" structure, similar to states recently reported in the hidden charm sector. The $Λ(1405)$ can be produced in the reaction $γp \rightarrow K^+Λ(1405)$. The pure I=0 decay mode into $Σ^0π^0$ is prohibited for the mass-overlapping $Σ(1385)$. Combining a large aperture forward magnetic spectrometer and a central BGO crystal calorimeter, the BGO-OD experiment is ideally suited to measure this decay with the $K^+$ in the forward direction. Preliminary results are presented. *Supported by DFG (PN 388979758, 405882627).

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arXiv2020

Strangeness photoproduction at the BGO-OD experiment

The BGO-OD experiment at the University of Bonn's ELSA accelerator facility in Germany is ideally suited to investigate photoproduction at extreme forward angles. It combines a highly segmented BGO electromagnetic calorimeter at central angles and an open dipole magnetic spectrometer in the forward direction. This allows the detection of forward going kaons, and complex final states of mixed charge from hyperon decays. Current projects at the BGO-OD experiment include strangeness production of $γp \rightarrow K^+ Λ/Σ^0$ at forward angles, $K^0Σ^0$ with a deuteron target and $K^+Λ(1405)$ line shape and cross section measurements.

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arXiv2020

A new Monte Carlo-based fitting method

We present a new fitting technique based on the parametric bootstrap method, which relies on the idea to produce artificial measurements using the estimated probability distribution of the experimental data. In order to investigate the main properties of this technique, we develop a toy model and we analyze several fitting conditions with a comparison of our results to the ones obtained using both the standard $χ^2$ minimization procedure and a Bayesian approach. Furthermore, we investigate the effect of the data systematic uncertainties both on the probability distribution of the fit parameters and on the shape of the expected goodness-of-fit distribution. Our conclusion is that, when systematic uncertainties are included in the analysis, only the bootstrap procedure is able to provide reliable confidence intervals and p-values, thus improving the results given by the standard $χ^2$ minimization approach. Our technique is then applied to an actual physics process, the real Compton scattering off the proton, thus confirming both the portability and the validity of the bootstrap-based fit method.

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