K+Σ− photoproduction within an isobar model

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389005%3A_____%2F22%3A00568491" target="_blank" >RIV/61389005:_____/22:00568491 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1051/epjconf/202227102009" target="_blank" >http://dx.doi.org/10.1051/epjconf/202227102009</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/epjconf/202227102009" target="_blank" >10.1051/epjconf/202227102009</a>

Jazyk výsledku

angličtina

Název v původním jazyce

K+Σ− photoproduction within an isobar model

Popis výsledku v původním jazyce

We used an isobar model to study the K+Σ− photoproduction reaction on a neutron target with focus on the resonance region. In order to achieve a reasonable agreement with the data, we included spin-3/2 and spin-5/2 nucleon resonances in a consistent formalism together with a Δ resonance and two kaon resonances on top of the Born terms. The free parameters of the model were adjusted to the data from the CLAS and LEPS Collaborations on differential cross sections and photon beam asymmetry. The cornerstone of this analysis was an upgrade of the fitting method. Previously, we used only the plain χ2 minimization, which could not prevent us from overfitting the data. We, therefore, introduced a regularization method, the least absolute selection shrinkage operator (LASSO), which, together with information criteria, restricts the number of nonzero parameters and prevents us from overfitting the data. In our analysis, we arrived at two models, fit M, whose parameters were fitted with the MINUIT code only, and fit L, where we used the more advanced LASSO. Both models describe the data in a similar way and we observe only slight differences in the dσ/dΩ data description at very forward angles where the fit M is flat whereas the fit L produces two broad peaks, and in the photon beam asymmetries above 2 GeV at backward kaon angles where the fit M produces a bump. Surprisingly, no hyperon resonances are needed for the correct data description in these models. On the other hand, the N(1720)3/2+ nucleon resonance was found to be very important in both models.

Název v anglickém jazyce

K+Σ− photoproduction within an isobar model

Popis výsledku anglicky

We used an isobar model to study the K+Σ− photoproduction reaction on a neutron target with focus on the resonance region. In order to achieve a reasonable agreement with the data, we included spin-3/2 and spin-5/2 nucleon resonances in a consistent formalism together with a Δ resonance and two kaon resonances on top of the Born terms. The free parameters of the model were adjusted to the data from the CLAS and LEPS Collaborations on differential cross sections and photon beam asymmetry. The cornerstone of this analysis was an upgrade of the fitting method. Previously, we used only the plain χ2 minimization, which could not prevent us from overfitting the data. We, therefore, introduced a regularization method, the least absolute selection shrinkage operator (LASSO), which, together with information criteria, restricts the number of nonzero parameters and prevents us from overfitting the data. In our analysis, we arrived at two models, fit M, whose parameters were fitted with the MINUIT code only, and fit L, where we used the more advanced LASSO. Both models describe the data in a similar way and we observe only slight differences in the dσ/dΩ data description at very forward angles where the fit M is flat whereas the fit L produces two broad peaks, and in the photon beam asymmetries above 2 GeV at backward kaon angles where the fit M produces a bump. Surprisingly, no hyperon resonances are needed for the correct data description in these models. On the other hand, the N(1720)3/2+ nucleon resonance was found to be very important in both models.

Druh

D - Stať ve sborníku

CEP obor

—

OECD FORD obor

10304 - Nuclear physics

Projekt

<a href="/cs/project/GA19-19640S" target="_blank" >GA19-19640S: Studium interakcí hadronů, jejich produkce a vázaných stavů</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2022

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

EPJ Web of Conferences

ISBN

—

ISSN

2100-014X

e-ISSN

2100-014X

Počet stran výsledku

4

Strana od-do

02009

Název nakladatele

EDP Science

Místo vydání

Les Ulis

Místo konání akce

Prague

Datum konání akce

27. 6. 2022

Typ akce podle státní příslušnosti

WRD - Celosvětová akce

Kód UT WoS článku

—