Inclusive e+e− production in collisions of pions with protons and nuclei in the second resonance region of baryons

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389005%3A_____%2F25%3A00619781" target="_blank" >RIV/61389005:_____/25:00619781 - isvavai.cz</a>

Result on the web

<a href="https://journals.aps.org/prc/abstract/10.1103/PhysRevC.111.024908" target="_blank" >https://journals.aps.org/prc/abstract/10.1103/PhysRevC.111.024908</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1103/PhysRevC.111.024908" target="_blank" >10.1103/PhysRevC.111.024908</a>

Result language

angličtina

Original language name

Inclusive e+e− production in collisions of pions with protons and nuclei in the second resonance region of baryons

Original language description

Inclusive e(+) e(-) production has been studied with HADES in pi(-) + p, pi(-) + C, and pi(-) + CH2 reactions, using the GSI pion beam at root s(pi p) = 1.49 GeV. Invariant mass and transverse momentum distributions have been measured and reveal contributions from Dalitz decays of pi(0), eta mesons, and baryon resonances. The transverse momentum distributions are very sensitive to the underlying kinematics of the various processes. The baryon contribution exhibits a deviation up to a factor seven from the QED reference expected for the dielectron decay of a hypothetical pointlike baryon with the production cross section constrained from the inverse gamma n -> pi(-) p reaction. The enhancement is attributed to a strong four-momentum squared dependence of the timelike electromagnetic transition form factors as suggested by vector meson dominance (VMD). Two versions of the VMD that differ in the photon-baryon coupling have been applied in simulations and compared to data. VMD1 (or two-component VMD) assumes a coupling via the rho meson and a direct coupling of the photon, while in VMD2 (or strict VMD) the coupling is only mediated via the rho meson. The VMD2 model, frequently used in transport calculations for dilepton decays, is found to overestimate the measured dielectron yields, while a good description of the data can be obtained with the VMD1 model assuming no phase difference between the two amplitudes. Similar descriptions have also been obtained using a timelike baryon transition form factor model where the pion cloud plays the major role.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10303 - Particles and field physics

Project

Result was created during the realization of more than one project. More information in the Projects tab.

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2025

Confidentiality

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

Name of the periodical

Physical Review C

ISSN

2469-9985

e-ISSN

2469-9993

Volume of the periodical

111

Issue of the periodical within the volume

2

Country of publishing house

US - UNITED STATES

Number of pages

13

Pages from-to

0204908

UT code for WoS article

001459938300001

EID of the result in the Scopus database

2-s2.0-85219705384