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<p>In the generalized matter-geometry coupling theory, we investigate the physical characteristics and causality of some new cosmological models for a flat, homogeneous, and isotropic spacetime filled with stiff-fluid, radiation, dust, and curvature fluid sources. We obtain a particular cosmological model corresponding to each source fluid, called Models I, II, III, and IV, respectively. We make observational constraints on each model using the joint analysis of the 31 Cosmic Chronometer (CC) Hubble dataset and 1701 Pantheon+SH0ES datasets to estimate the current values of model parameters. Using these statistical results, we have analyzed the information criteria, effective EoS parameter, causality of the models, and viability of this generalized gravity theory. Subsequently, we investigate the effective equation of state and deceleration parameter for each model. We found that all models in the late-time universe exhibit an acceleration phase, and Models II and IV show a late-time accelerating phase of the expanding universe with a transition point. We found the current values of the deceleration parameter in the range <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(-0.9334\le q_{0}\le -0.5294\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>-</mo> <mn>0.9334</mn> <mo>≤</mo> <msub> <mi>q</mi> <mn>0</mn> </msub> <mo>≤</mo> <mo>-</mo> <mn>0.5294</mn> </mrow> </math></EquationSource> </InlineEquation> with transition redshift <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(0.5122\le z_{t}\le 0.586\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>0.5122</mn> <mo>≤</mo> <msub> <mi>z</mi> <mi>t</mi> </msub> <mo>≤</mo> <mn>0.586</mn> </mrow> </math></EquationSource> </InlineEquation> and the effective EoS parameter in the range <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(-0.9556\le \omega _\textrm{eff}\le -0.6863.\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>-</mo> <mn>0.9556</mn> <mo>≤</mo> <msub> <mi>ω</mi> <mtext>eff</mtext> </msub> <mo>≤</mo> <mo>-</mo> <mn>0.6863</mn> <mo>.</mo> </mrow> </math></EquationSource> </InlineEquation> We analyzed the square sound speed condition <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(c_{s}^{2}\le c^{2}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msubsup> <mi>c</mi> <mrow> <mi>s</mi> </mrow> <mn>2</mn> </msubsup> <mo>≤</mo> <msup> <mi>c</mi> <mn>2</mn> </msup> </mrow> </math></EquationSource> </InlineEquation> for each model.</p>

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Cosmological implications and causality in \(f(R, L_{m}, T)\) gravity theory with observational constraints

  • 期刊论文

  • 发表日期：

    2026年7月20日

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  • Dinesh Chandra Maurya,
  • Javlon Rayimbaev,
  • Inomjon Ibragimov,
  • Sokhibjan Muminov

摘要

In the generalized matter-geometry coupling theory, we investigate the physical characteristics and causality of some new cosmological models for a flat, homogeneous, and isotropic spacetime filled with stiff-fluid, radiation, dust, and curvature fluid sources. We obtain a particular cosmological model corresponding to each source fluid, called Models I, II, III, and IV, respectively. We make observational constraints on each model using the joint analysis of the 31 Cosmic Chronometer (CC) Hubble dataset and 1701 Pantheon+SH0ES datasets to estimate the current values of model parameters. Using these statistical results, we have analyzed the information criteria, effective EoS parameter, causality of the models, and viability of this generalized gravity theory. Subsequently, we investigate the effective equation of state and deceleration parameter for each model. We found that all models in the late-time universe exhibit an acceleration phase, and Models II and IV show a late-time accelerating phase of the expanding universe with a transition point. We found the current values of the deceleration parameter in the range \(-0.9334\le q_{0}\le -0.5294\) - 0.9334 ≤ q 0 ≤ - 0.5294 with transition redshift \(0.5122\le z_{t}\le 0.586\) 0.5122 ≤ z t ≤ 0.586 and the effective EoS parameter in the range \(-0.9556\le \omega _\textrm{eff}\le -0.6863.\) - 0.9556 ≤ ω eff ≤ - 0.6863 . We analyzed the square sound speed condition \(c_{s}^{2}\le c^{2}\) c s 2 ≤ c 2 for each model.