arXiv subjects

Iu. Skorodumina

Publications and source records attributed to Iu. Skorodumina.

3 recordsLinked to original sources

arXiv2017

TWOPEG-D: An Extension of TWOPEG for the Case of a Moving Proton Target

A new TWOPEG-D version of the event generator TWOPEG was developed. This new version simulates the quasi-free process of double-pion electroproduction off the proton that moves in the deuteron target. The underlying idea is the equivalence of the moving proton experiment performed with fixed laboratory beam energy to the proton at rest experiment conducted with effective beam energy different from the laboratory one. This effective beam energy differs event by event and is determined by the boost from the Lab system to the proton rest frame. The Fermi momentum of the target proton is generated according to the Bonn potential. The specific aspects of the deuteron target data analysis are discussed. The plots that illustrate the performance of TWOPEG-D are given. The link to the code is provided. The generator was tested in the analysis of the CLAS data on electron scattering off the deuteron target.

physics.data-an↗

arXiv2017

TWOPEG: An Event Generator for Charged Double Pion Electroproduction off Proton

The new event generator TWOPEG for the channel $e p \rightarrow e' p' π^{+} π^{-}$ has been developed. It uses an advanced method of event generation with weights and employs the five-fold differential structure functions from the recent versions of the JM model fit to all results on charged double pion photo- and electroproduction cross sections from CLAS (both published and preliminary). In the areas covered by measured CLAS data, TWOPEG successfully reproduces the available integrated and single-differential double pion cross sections. To estimate the cross sections in the regions not covered by data, a specialized extrapolation procedure is applied. The EG currently covers a kinematical area in $Q^2$ starting from 0.0005 GeV$^2$ and in $W$ from the reaction threshold up to 4.5 GeV. TWOPEG allows to obtain the cross section values from the generated distributions and simulates radiative effects. The link to the code is provided. TWOPEG has already been used in CLAS data analyses and in PAC proposal preparations and is designed to be used during the CLAS12 era.

physics.data-an↗

arXiv2015

New Results from the Studies of the $N(1440)1/2^+$, $N(1520)3/2^-$, and $Δ(1620)1/2^-$ Resonances in Exclusive $ep \to e'p' π^+ π^-$ Electroproduction with the CLAS Detector

The transition helicity amplitudes from the proton ground state to the $N(1440)1/2^+$, $N(1520)3/2^-$, and $Δ(1620)1/2^-$ resonances ($γ_vpN^*$ electrocouplings) were determined from the analysis of nine independent one-fold differential $π^+ π^- p$ electroproduction cross sections off a proton target, taken with CLAS at photon virtualities 0.5 GeV$^2$ $< Q^2 <$ 1.5 GeV$^2$. The phenomenological reaction model employed for separation of the resonant and non-resonant contributions to this exclusive channel was further developed. The $N(1440)1/2^+$, $N(1520)3/2^-$, and $Δ(1620)1/2^-$ electrocouplings were obtained from the resonant amplitudes of charged double-pion electroproduction off the proton in the aforementioned area of photon virtualities for the first time. Consistent results on $γ_vpN^*$ electrocouplings available from independent analyses of several $W$-intervals with different non-resonant contributions offer clear evidence for the reliable extraction of these fundamental quantities. These studies also improved the knowledge on hadronic branching ratios for the $N(1440)1/2^+$, $N(1520)3/2^-$, and $Δ(1620)1/2^-$ decays to the $πΔ$ and $ρN$ final states. These new results provide a substantial impact on the QCD-based approaches that describe the $N^*$ structure and demonstrate the capability to explore fundamental ingredients of the non-perturbative strong interaction that are behind the excited nucleon state formation.

nucl-ex↗