https://doi.org/10.1140/epjc/s10052-025-14309-4
Regular Article - Theoretical Physics
Exploring cosmological implications of the modified Raychaudhuri equation in non-gravitating vacuum energy theory
1
Department of Physics, Prabhat Kumar College, Contai, 721404, Purba Medinipur, West Bengal, India
2
Department of Physics, Raiganj University, Raiganj, 733 134, Uttar Dinajpur, West Bengal, India
3
Department of Physics, Ben-Gurion University of the Negev, Beersheba, Israel
4
Frankfurt Institute for Advanced Studies (FIAS), Ruth-Moufang-Strasse 1, 60438, Frankfurt am Main, Germany
5
Bahamas Advanced Study Institute and Conferences, 4A Ocean Heights, Hill View Circle, Stella Maris, Long Island, Bahamas
6
Institute of Astronomy, Space and Earth Science (IASES), 700054, Kolkata, India
Received:
26
February
2025
Accepted:
14
May
2025
Published online:
27
May
2025
This article investigates the modified Raychaudhuri Equation (RE) in the context of Non-Gravitating Vacuum Energy (NGVE) theory and its implications for various cosmological characteristics. The equation is formulated based on the NGVE framework, in which global scale invariance generates a unique geometry. The newly developed geometry introduces a metric that is conformally connected to the conventional metric, with the conformal factor dependent on scalar field potentials. The cosmological study is carried out under the framework of a flat Friedmann–Lemaître–Robertson–Walker (FLRW) universe. Assuming matter behaves as an ideal fluid in the modified geometry, we formulate models for conditional expansion, collapse, and steady state, governed by the scalar field 
. In this context, the caustic solution and the focusing theorem are also studied. Scalar field solutions for exponential and power-law scale factors are also derived using NGVE theory’s equations of motion. Finally, graphical analysis is used to investigate the behavior of the interaction terms that appear in the modified RE under these scale factors.
© The Author(s) 2025
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