Horvat, S., Magas, V. K., Strottman, D. D., & Csernai, L. P. (2010). Entropy development in ideal relativistic fluid dynamics with the Bag Model equation of state. Phys. Lett. B, 692(4), 277–280.
Abstract: We consider an idealized situation where the Quark-Gluon Plasma (QGP) is described by a perfect, (3 + 1)-dimensional fluid dynamic model starting from an initial state and expanding until a final state where freeze-out and/or hadronization takes place. We study the entropy production with attention to effects of (i) numerical viscosity, (ii) late stages of flow where the Bag Constant and the partonic pressure are becoming similar, (iii) and the consequences of final freeze-out and constituent quark matter formation.
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Navarro, J., & Guardiola, R. (2011). Thermal Effects on Small Para-Hydrogen Clusters. Int. J. Quantum Chem., 111(2), 463–471.
Abstract: A brief review of different quantum Monte Carlo simulations of small (p-H-2)(N) clusters is presented. The clusters are viewed as a set of N structureless p-H-2 molecules, interacting via an isotropic pairwise potential. Properties as superfluidity, magic numbers, radial structure, excitation spectra, and abundance production of (p-H-2)(N) clusters are discussed and, whenever possible, a comparison with He-4(N) droplets is presented. All together, the simulations indicate that temperature has a paradoxical effect of the properties of (p-H-2)(N) clusters, as they are solid-like at high T and liquid-like at low T, due to quantum delocalization at the lowest temperature.
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Jeong, K. S., & Park, W. I. (2023). Cosmology with a supersymmetric local B – L model. J. Cosmol. Astropart. Phys., 11(11), 016–34pp.
Abstract: We propose a minimal gauged U(1)(B-L) extension of the minimal supersymmetric Standard Model (MSSM) which resolves the cosmological moduli problem via thermal inflation, and realizes late-time Affleck-Dine leptogensis so as to generate the right amount of baryon asymmetry at the end of thermal inflation. The present relic density of dark matter can be explained by sneutrinos, MSSM neutralinos, axinos, or axions. Cosmic strings from U(1)(B-L) breaking are very thick, and so the expected stochastic gravitational wave background from cosmic string loops has a spectrum different from the one in the conventional Abelian-Higgs model, as would be distinguishable at least at LISA and DECIGO. The characteristic spectrum is due to a flat potential, and may be regarded as a hint of supersymmetry. Combined with the resolution of moduli problem, the expected signal of gravitational waves constrains the U(1)(B-L) breaking scale to be O(10(12-13)) GeV. Interestingly, our model provides a natural possibility for explaining the observed ultra-high-energy cosmic rays thanks to the fact that the core width of strings in our scenario is very large, allowing a large enhancement of particle emissions from the cusps of string loops. Condensation of LHu flat-direction inside of string cores arises inevitably and can also be the main source of the ultra-high-energy cosmic rays accompanied by ultra-high-energy lightest supersymmetric particles.
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Ghoshal, A., Gouttenoire, Y., Heurtier, L., & Simakachorn, P. (2023). Primordial black hole archaeology with gravitational waves from cosmic strings. J. High Energy Phys., 08(8), 196–43pp.
Abstract: Light primordial black holes (PBHs) with masses smaller than 10(9) g (10(-24) M-circle dot) evaporate before the onset of Big-Bang nucleosynthesis, rendering their detection rather challenging. If efficiently produced, they may have dominated the universe energy density. We study how such an early matter-dominated era can be probed successfully using gravitational waves (GW) emitted by local and global cosmic strings. While previous studies showed that a matter era generates a single-step suppression of the GW spectrum, we instead find a double-step suppression for local-string GW whose spectral shape provides information on the duration of the matter era. The presence of the two steps in the GW spectrum originates from GW being produced through two events separated in time: loop formation and loop decay, taking place either before or after the matter era. The second step – called the knee – is a novel feature which is universal to any early matter-dominated era and is not only specific to PBHs. Detecting GWs from cosmic strings with LISA, ET, or BBO would set constraints on PBHs with masses between 10(6) and 10(9) g for local strings with tension G μ= 10(-11), and PBHs masses between 10(4) and 10(9) g for global strings with symmetry-breaking scale eta = 10(15) GeV. Effects from the spin of PBHs are discussed.
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Fu, B. W., Ghoshal, A., King, S. F., & Hossain Rahat, M. (2024). Type-I two-Higgs-doublet model and gravitational waves from domain walls bounded by strings. J. High Energy Phys., 08(8), 237–25pp.
Abstract: The spontaneous breaking of a U(1) symmetry via an intermediate discrete symmetry may yield a hybrid topological defect of domain walls bounded by cosmic strings. The decay of this defect network leads to a unique gravitational wave signal spanning many orders in observable frequencies, that can be distinguished from signals generated by other sources. We investigate the production of gravitational waves from this mechanism in the context of the type-I two-Higgs-doublet model extended by a U(1)R symmetry, that simultaneously accommodates the seesaw mechanism, anomaly cancellation, and eliminates flavour-changing neutral currents. The gravitational wave spectrum produced by the string-bounded-wall network can be detected for U(1)R breaking scale from 1012 to 1015 GeV in forthcoming interferometers including LISA and Einstein Telescope, with a distinctive f3 slope and inflexion in the frequency range between microhertz and hertz.
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