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Jovan Alfian Djaja

Publications and source records attributed to Jovan Alfian Djaja.

3 recordsLinked to original sources

Electromagnetic Production of Kaons on the Nucleon

Studies of the electromagnetic production of strange quarks began in the 1950s as something of a curiosity that puzzled experimentalists and theorists alike. As the datasets increased, concomitant advances in theoretical models were realized. A paradigm shift occurred in the 1990s with the development of second-generation facilities at ELSA, MAMI, SPring-8, and JLab, which brought nuclear physics experiments forward by orders of magnitude in counting statistics compared to the first-generation efforts. This was an utter boon to strangeness physics investigations, and to date, more than 50 dedicated experiments in kaon photo- and electroproduction have been completed at facilities around the world, leading to a host of experimental observables that have enabled significant advances in the exploration of strongly interacting systems that decay via $s\bar{s}$ quark pair creation. This review was designed to provide the first-ever in-depth overview of both the experimental and theoretical progress in the field of the electromagnetic production of strangeness. This work looks back over 70 years of past developments, discusses ongoing work and near-term plans, and details future possibilities being considered for third-generation facilities. Throughout this work, the primary impacts of these explorations are highlighted, along with connections to a wide range of related phenomenological applications. An important goal of this review is to provide a complete, self-contained guide into this field prepared at a level that is relevant for both new and seasoned scientists, whether experimentalists, phenomenologists, or theorists, to better understand what has been accomplished by so many dedicated folks-each building on what has come before-and to appreciate the exciting future potential for continued studies in this area. A more complete abstract is provided in the paper.

hep-ph↗

New Elementary Operator for Kaon Photoproduction on the Nucleon and Nuclei

A new elementary operator for kaon photoproduction on the nucleon and nuclei has been developed within a Feynman diagrammatic framework. By fitting the unknown coupling strengths at the electromagnetic and hadronic vertices of the baryon resonances to all available experimental data across the six isospin channels, the model achieves excellent agreement with the data. The operator includes 26 nucleon resonances in the $KΛ$ channels and 17 additional $Δ$ resonances in the $KΣ$ channels. For applications to nuclear reactions, such as hypernuclear photoproduction, the operator is formulated in Pauli space, allowing a straightforward implementation of the nonrelativistic approximation. Several alternative forms for expressing the operator output are proposed. In one of them, the spin operators and photon polarization vectors are separated from the operator, since both are frame dependent, thereby enhancing its versatility in nuclear applications.

nucl-th↗

New Isobar Models for $K^+Λ$ Electroproduction

The electroproduction of kaon on proton has been studied using two covariant isobar models. The models incorporate propagators and vertex factors developed in our previous works. In total, the current study includes 26 nucleon resonances and 20 hyperon resonances, with spins up to 13/2. In the electromagnetic vertices, we consider two alternative electromagnetic form factors alongside the commonly used dipole model. The unknown parameters in the models, such as longitudinal coupling constants and form factor cutoffs, are determined by fitting the calculated observables to nearly 2000 experimental data points. The resulting models demonstrate satisfactory consistency with the available experimental data.

hep-ph↗