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Chalis Setyadi

Publications and source records attributed to Chalis Setyadi.

6 recordsLinked to original sources
arXiv2025

Determination of the HERA coherent diffractive $J/\psi$ production cross section via artificial neural network

An exclusive coherent diffractive $J/\psi$ production dataset from HERA, covering a large kinematic range in the photon virtuality $Q^2$, the squared momentum transfer $t$, and the photon-proton center-of-mass energy $W$, has been analyzed using various theoretical models with different approaches. In common model analyses, the inherent assumptions and limited kinematic applicability somewhat restrict the predictive power of the models, resulting in model-dependent prediction results. In this paper, we present our model-independent approach for the same reaction process and dataset, utilizing an artificial neural network (ANN) technique. The prediction of the best ANN model for the HERA differential cross-section dataset over a range of $W$, $Q^2$, and $t$ is obtained. We then extend the ANN model by combining the HERA and LHC data at various values of $W$ to predict the total photoproduction cross-section and demonstrate how to extract the exponential slope $b$. We find that the exponential slope $b$ strongly depends on $Q^2$ and $W$.

hep-ph↗
arXiv2025

Constraining the proton transverse partonic distribution through coherent diffractive $J/\psi$ production at HERA within a static Gaussian hot spot model

We investigate the transverse parton distribution of the proton through the t-dependence of the coherent J/psi differential cross section extracted from HERA measurements in the small-x regime. Employing a simple static Gaussian hot spot model inspired by the large-x three-valence-quark picture of the proton, we introduce three geometric degrees of freedom of each hot spot: the Gaussian width of each hot spot, the spatial distance of the valence quarks from the proton center, and their azimuthal orientation. In the simplest implementation, the valence quarks are assumed to form a symmetric triangular configuration. We find that variations in these geometric structures significantly influence the t-slope of the coherent cross section. In particular, the rotational degree of freedom strongly affects the cross section at t > 0.5 GeV^2, while the small-t region remains largely insensitive to variations in this parameter.

hep-ph↗
arXiv2025

A Brief History and Outlook of Hadronic Physics in Indonesia

Hadronic physics has gradually emerged as one of the growing research frontiers in Indonesia, driven by efforts to better understand the properties of the strong interaction and the internal structure of hadrons from the fundamental principles of Quantum Chromodynamics. In the last few decades, Indonesian researchers have made significant contributions to developing various theoretical and phenomenological aspects of hadrons. In addition, on the experimental side, Indonesian scientists have participated in hadron experiment facilities overseas, such as the ALICE collaboration at CERN, which has strengthened the scientific activities and networks and has supported the training of young Indonesian researchers. In the present paper, we review Indonesian scientists' contributions to hadronic physics, highlight ongoing research directions in both experimental and theoretical, and outline strategies for future development toward integration into the international hadronic physics community.

hep-ph↗
arXiv2023

Probing gluon GTMDs through exclusive coherent diffractive processes

We extend a previous GTMD model to improve the description of the HERA data on diffractive dijet production, and include exclusive coherent diffractive $J/ψ$ production data. We find that within our gluon GTMD model context and assumptions, there is considerable tension between the data for these two types of processes concerning the $t$ dependence. Photo- and electroproduction data for protons and nuclei from EIC and UPC data from LHC and RHIC can help to establish whether a common GTMD description is possible, as one would expect, and to facilitate studies of such data we provide predictions for the various experiments. We point out explicitly in which sense this goes beyond the description in terms of GPDs.

hep-ph↗
arXiv2021

GTMD model predictions for diffractive dijet production at EIC

In this paper we consider a small-$x$ model for gluon GTMDs that we fit to data on diffractive dijet production in electron-proton collisions obtained by HERA's H1 Collaboration. Assuming a small number of free parameters, each with a physical motivation, we are able to describe those data fairly well and with this model we obtain predictions for the EIC for both electroproduction and photoproduction which may allow to further test the underlying GTMD description. In the general discussion of the impact parameter dependence we recall some subtle issues related to localization of states, choice of frames, and discuss what these aspects imply for the range of applicability of the model.

hep-ph↗