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Pornrad Srisawad

Publications and source records attributed to Pornrad Srisawad.

7 recordsLinked to original sources

arXiv2026

Kruglov-entropy cosmology from apparent-horizon thermodynamics: background dynamics and observational constraints

We investigate two late-time cosmological models generated by Kruglov's nonadditive entropy at the apparent horizon. Model I, originally derived by Kruglov, follows the Cai--Kim thermodynamic construction and leads to an implicit modified Friedmann equation, whereas Model II, proposed and derived in this work, is obtained from an entropy-integral prescription and contains an effective vacuum contribution. We formulate both models in terms of the dimensionless Hubble parameter, include radiation, impose exact present-day closure, and evolve the physical branch using analytic derivatives of the implicit Friedmann equations. We constrain the models with DESI DR2 baryon acoustic oscillations and a compressed CMB likelihood, with and without DES-Y5 Type-Ia supernovae. Model I is driven to a markedly lower Hubble constant, $H_0\simeq62.4,\mathrm{km,s^{-1},Mpc^{-1}}$ for the combined data, and remains non-phantom with $w_{\rm DE,0}\simeq-0.814$; it is strongly disfavoured relative to flat $Λ$CDM. Model II stays close to $Λ$CDM in the standard cosmological parameters and gives $w_{\rm DE,0}\simeq-1.003$, while its two entropy-sector parameters remain strongly degenerate. Its best-fit likelihood is comparable to $Λ$CDM, but the additional parameters are not supported by information criteria. These results show that the two thermodynamic realizations of the same nonadditive entropy have sharply different phenomenological consequences at the homogeneous-background level. In summary, the observational plausibility of entropy-based cosmology hinges critically on how the generalized horizon entropy is incorporated into the Friedmann dynamics.

astro-ph.CO↗

arXiv2026

Hypernucleus production in p+Au reactions at the FAIR facility

We explore the production of hypernuclei in p+Au reactions using the UrQMD model accompanied by a standard phase space coalescence model. We focus on the proton beam energy range of $E_{\rm lab}= 5 - 30$ GeV as this energy range will be investigated by the CBM-experiment at the upcoming FAIR facility. Starting from proton, $Λ$, $Σ$, $Ξ$ and $Ω$ production, we predict the yields, rapidity and transverse momentum distributions of $^{3}_ΛH$, $^{4}_ΛH$, $Ξ$N and $Ξ$NN hypernuclei. We conclude that the production rates of novel multi-strange hypernuclei are well within the reach of the CBM-experiment.

nucl-th↗

arXiv2026

$f_0(980)$ production from $K\bar{K}$ coalescence in pp collisions at $\sqrt{s}=5.02$ TeV within UrQMD

We investigate the production of the scalar meson $f_0(980)$ in proton--proton collisions at $\sqrt{s}=5.02$~TeV using the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) transport model supplemented with a $K\bar{K}$ coalescence afterburner. After conservatively tuning the UrQMD string-fragmentation parameters, the model reproduces the bulk charged-kaon production in the low-to-intermediate transverse-momentum region, providing the kaon phase-space distribution used as input for the coalescence calculation. In the present implementation, both charged and neutral kaon--antikaon pairs are considered, and each accepted $K\bar{K}$ pair is assigned to the isoscalar $f_0(980)$ and isovector $a_0(980)$ channels with an equal Monte Carlo probability. Using the updated integration analysis, we find that $Δp=0.4$~GeV/$c$ gives the best directly simulated agreement with the ALICE $p_T$ spectrum and integrated yield, while a linear interpolation between the neighboring points at $Δp=0.3$ and $0.4$~GeV/$c$ yields an interpolated optimum of $Δp^{\ast}\approx0.365$~GeV/$c$. Within this constrained hadronic coalescence framework, the measured $f_0(980)$ production is reasonably described, and the results are consistent with interpreting the $f_0(980)$ as a late-stage $K\bar{K}$ molecular configuration formed near kinetic freeze-out in small collision systems.

hep-ph↗

arXiv2025

Cosmological dynamics of holographic dark energy with non-minimally coupled scalar field

In this study, we consider FRW universe filled with matter, non-minimally coupling (NMC) scalar field under $V(ϕ) = V_{0}ϕ^{2}$ potential and holographic vacuum energy. Dark energy is contributed from both holographic vacuum energy and the NMC scalar field. NMC effective gravitational constant $G_\text{eff}(ϕ)$, is naturally defined at the action level. Therefore, the gravitational constant in the holographic vacuum density is an effective one, i.e. $ ρ_Λ = {3c^{2}}/{8πG_{\text{eff}}L^{2}}\,. $ Apparent horizon is chosen as IR holographic cutoff scale as it is a trapped null surface. There are nine fixed points in this dynamical system with four independent dimensionless parameters. We consider flat case and find that viable cosmological evolution follows the sequence: an initial stiff-fluid-dominated phase, transitioning through a nearly dust-dominated era, and eventually reaching a stable dark energy-dominating state. Stability analysis requires that $ξ<0$ and $0 < c < 1$ for the theory to be physically valid. Since zero NMC coupling, $ξ=0$, is not allowed in the autonomous system, the model can not completely recover canonical scalar field case. That is to say, as $ξ\rightarrow 0^-$ and $c \rightarrow 0^+$, the model can only approach the canonical scalar case but can not completely recover it. To approach dust or stiff fluid dominations, both magnitudes of the NMC coupling and the holographic parameter must be small. Numerical integration shows that for any allowed values of $ξ$ and $c$, $w_\text{eff}$ approaches $-1$ at late times. Increasing of $c$ does not change shape of the $w_{\rm eff}$, but larger $c$ increases $w_\text{eff}$. As $ξ$ becomes stronger, dust era gradually disappears. Good behaviors of the dynamics require $-1 \ll ξ<0$ and $0 < c \ll 1$.

gr-qc↗

arXiv2024

Dynamics of holographic dark energy with apparent-horizon cutoff and non-minimal derivative coupling gravity in non-flat FLRW universe

Background cosmological dynamics for a universe with matter, a scalar field non-minimally derivative coupling to Einstein tensor under power-law potential and holographic vacuum energy is considered here. The holographic IR cutoff scale is apparent horizon which, for accelerating universe, forms a trapped null surface in the same spirit as blackhole's event horizon. For non-flat case, effective gravitational constant cannot be expressed in the Friedmann equation. Therefore holographic vacuum density is defined with standard gravitational constant instead of the effective one. Dynamical and stability analysis shows four independent fixed points. One fixed point is stable and it corresponds to $w_{\text{eff}} = -1$. One branch of the stable fixed-point solutions corresponds to de-Sitter expansion. The others are either unstable or saddle nodes. Numerical integrations of the dynamical system are performed and plotted confronting with $H(z)$ data. It is found that for flat universe, $H(z)$ observational data favors large negative value of NMDC coupling, $κ$. Larger holographic contribution, $c$, and larger negative NMDC coupling increase slope and magnitude of the $w_{\text{eff}}$ and $H(z)$. Negative $κ$, can contribute to phantom equation of state, $w_{\text{eff}} < -1$. The NMDC-spatial curvature coupling could have phantom energy contribution. Free negative spatial curvature term can also contribute to phantom equation of state, but only with significantly large negative value of the spatial curvature. The model could give phantom equation of state for $κ= -200$ and high value of $c$ for both flat and open cases.

gr-qc↗

arXiv2019

Forward and backward comparative study of jet properties in pp collisions at \sqrt{s}=7 TeV

We propose a forward method, based on the PYTHIA6.4, to study theoretically the jet properties in the ultra-relativistic pp collisions. In the forward method, the partonic initial states are first generated with PYTHIA6.4 and then hadronized in the Lund srting fragmentation regime, and finally hadronic jets are constructed from the created hadrons. Jet properties calculated in the forward method for pp collisions at \sqrt{s}=7 TeV are comparable with the corresponding ones calculated with usual anti-k_t algorithm (backward method) in the PYTHIA6.4. The comparison between the results in the backward and forward methods may bring benefit to the understanding of the partonic origin of jets in the backward method.

nucl-th↗

arXiv2014

Properties of strange vector mesons in dense and hot matter

We investigate the in-medium properties of strange vector mesons ($K^*$ and $\bar K^*$) in dense and hot nuclear matter based on chirally motivated models of the meson selfenergies. We parameterise medium effects as density or temperature dependent effective masses and widths, obtain the vector meson spectral functions within a Breit-Wigner prescription (as often used in transport simulations) and study whether such an approach can retain the essential features of full microscopic calculations. For $μ_B\ne 0$ the medium corrections arise from $\bar K^* (K^*) N$ scattering and the $\bar K^* (K^*) \to \bar K (K) π$ decay mode (accounting for in-medium $\bar K (K)$ dynamics). We calculate the scattering contribution to the $K^*$ selfenergy based on the hidden local symmetry formalism for vector meson nucleon interactions, whereas for the $\bar K^*$ selfenergy we implement recent results from a selfconsistent coupled-channel determination within the same approach. For $μ_B\simeq 0$ and finite temperature we rely on a phenomenological approach for the kaon selfenergy in a hot pionic medium consistent with chiral symmetry, and evaluate the $\bar K^* (K^*) \to \bar K (K) π$ decay width. The emergence of a mass shift at finite temperature is studied with a dispersion relation over the imaginary part of the vector meson selfenergy.

hep-ph↗