Izadi, A., Shacker, S. S., Olmo, G. J., & Banerjee, R. (2018). Observational effects of varying speed of light in quadratic gravity cosmological models. Int. J. Geom. Methods Mod. Phys., 15(5), 1850084–16pp.
Abstract: We study different manifestations of the speed of light in theories of gravity where metric and connection are regarded as independent fields. We find that for a generic gravity theory in a frame with locally vanishing affine connection, the usual degeneracy between different manifestations of the speed of light is broken. In particular, the space-time causal structure constant (c(ST)) may become variable in that local frame. For theories of the form f(R, R-mu nu R-mu nu), this variation in c(ST) has an impact on the definition of the luminosity distance (and distance modulus), which can be used to confront the predictions of particular models against Supernovae type Ia (SN Ia) data. We carry out this test for a quadratic gravity model without cosmological constant assuming (i) a constant speed of light and (ii) a varying speed of light (VSL), and find that the latter scenario is favored by the data.
|
Araujo Filho, A. A., Reis, J. A. A. S., & Ghosh, S. (2023). Quantum gases on a torus. Int. J. Geom. Methods Mod. Phys., 20(10), 2350178–19pp.
Abstract: This paper is aimed at studying the thermodynamic properties of quantum gases confined to a torus. To do that, we consider noninteracting gases within the grand canonical ensemble formalism. In this context, fermions and bosons are taken into account and the calculations are properly provided in both analytical and numerical manners. In particular, the system turns out to be sensitive to the topological parameter under consideration: the winding number. Furthermore, we also derive a model in order to take into account interacting quantum gases. To corroborate our results, we implement such a method for two different scenarios: a ring and a torus.
|
Araujo Filho, A. A. (2023). Thermodynamics of massless particles in curved spacetime. Int. J. Geom. Methods Mod. Phys., 12(13), 2350226–40pp.
Abstract: This work is devoted to study the behavior of massless particles within the context of curved spacetime. In essence, we investigate the consequences of the scale factor C(?) of the Friedmann-Robertson-Walker metric in the Einstein-aether formalism to study photon-like particles. To do so, we consider the system within the canonical ensemble formalism in order to derive the following thermodynamic state quantities: spectral radiance, Helmholtz free energy, pressure, entropy, mean energy and the heat capacity. Moreover, the correction to the Stefan-Boltzmann law and the equation of states are also provided. Particularly, we separate our study within three distinct cases, i.e. s = 0, p = 0; s = 1, p = 1; s = 2, p = 1. In the first one, the results are derived numerically. Nevertheless, for the rest of the cases, all the calculations are accomplished analytically showing explicitly the dependence of the scale factor C(?) and the Riemann zeta function ?(s). Furthermore, our analyses are accomplished in general taking into account three different regimes of temperature of the universe, i.e. the inflationary era (T = 10(13)GeV), the electroweak epoch (T = 10(3)GeV) and the cosmic microwave background (T = 10(-13)GeV).
|
Chen, Y. H., Yao, D. L., & Zheng, H. Q. (2018). A Study of rho-omega Mixing in Resonance Chiral Theory. Commun. Theor. Phys., 69(1), 50–58.
Abstract: The strong and electromagnetic corrections to rho-omega mixing are calculated using an SU(2) version of resonance chiral theory up to next-to-leading orders in 1/N-C expansion, respectively. Up to our accuracy, the effect of the momentum dependence of rho-omega mixing is incorporated due to the inclusion of loop contributions. We analyze the impact of rho-omega mixing on the pion vector form factor by performing numerical fit to the data extracted from e(+)e(-) -> pi(+)pi(-) and tau -> nu(tau)2 pi, while the decay width of omega -> pi(+)pi(-) is taken into account as a constraint. It is found that the momentum dependence is significant in a good description of the experimental data. In addition, based on the fitted values of the involved parameters, we analyze the decay width of omega -> pi(+)pi(-), which turns out to be highly dominated by the rho-omega mixing effect.
|
Shi, P. P., Baru, V., Guo, F. K., Hanhart, C., & Nefediev, A. (2024). Production of the X(4014) as the Spin-2 Partner of X(3872) in e + e – Collisions. Chin. Phys. Lett., 41(3), 031301–7pp.
Abstract: In 2021, the Belle collaboration reported the first observation of a new structure in the psi(2S)gamma final state produced in the two-photon fusion process. In the hadronic molecule picture, this new structure can be associated with the shallow isoscalar D*D* bound state and as such is an excellent candidate for the spin-2 partner of the X(3872) with the quantum numbers J(PC) = 2(++) conventionally named X-2. In this work we evaluate the electronic width of this new state and argue that its nature is sensitive to its total width, the experimental measurement currently available being unable to distinguish between different options. Our estimates demonstrate that the planned Super tau-Charm Facility offers a promising opportunity to search for and study this new state in the invariant mass distributions for the final states J/psi gamma and psi(2S)gamma.
|
Botella-Soler, V., & Glendinning, P. (2012). Emergence of hierarchical networks and polysynchronous behaviour in simple adaptive systems. EPL, 97(5), 50004–5pp.
Abstract: We describe the dynamics of a simple adaptive network. The network architecture evolves to a number of disconnected components on which the dynamics is characterized by the possibility of differently synchronized nodes within the same network (polysynchronous states). These systems may have implications for the evolutionary emergence of polysynchrony and hierarchical networks in physical or biological systems modeled by adaptive networks.
|
Baker, M. J., Bordes, J., Hong-Mo, C., & Tsun, T. S. (2013). On the corner elements of the CKM and PMNS matrices. EPL, 102(4), 41001–6pp.
Abstract: Recent experiments show that the top-right corner element (U-e3) of the PMNS matrix is small but nonzero, and suggest further via unitarity that it is smaller than the bottom-left corner element (U-tau 1). Here, it is shown that if to the assumption of a universal rank-one mass matrix, long favoured by phenomenologists, one adds that this matrix rotates with scale, then it follows that A) by inputting the mass ratios m(c)/m(t), m(s)/m(b), m(mu)/m(tau), and m(2)/m(3), i) the corner elements are small but nonzero, ii) V-ub < V-td, U-e3 < U-tau 1, iii) estimates result for the ratios V-ub/V-td and U-e3/U-tau 1, and B) by inputting further the experimental values of V-us, V-tb and U-e2, U-mu 3, iv) estimates result for the values of the corner elements themselves. All the inequalities and estimates obtained are consistent with present data within expectation for the approximations made.
|
Motohashi, H., & Starobinsky, A. A. (2017). Constant-roll inflation: Confrontation with recent observational data. EPL, 117(3), 39001–3pp.
Abstract: The previously proposed class of phenomenological inflationary models in which the assumption of inflaton slow-roll is replaced by the more general, constant-roll condition is compared with the most recent cosmological observational data, mainly the Planck ones. Models in this two-parametric class which remain viable appear to be close to the slow-roll ones, and their inflaton potentials are close to (but still different from) that of the natural inflation model. The permitted regions for the two model parameters are presented.
|
Bueno Rogerio, R. J., Lima, R. D., Duarte, L., Hoff da Silva, J. M., Dias, M., & Senise, C. R. (2019). Mass-dimension-one fermions and their gravitational interaction. EPL, 128(2), 20004–6pp.
Abstract: We investigate in detail the interaction between the spin-(1/2) field endowed with mass dimension one and the graviton. We obtain an interaction vertex that combines the characteristics of scalar-graviton and Dirac's fermion-graviton vertices, due to the scalar-dynamic attribute and the fermionic structure of the mass-dimension-one field. It is shown that this vertex obeys the Ward-Takahashi identity, ensuring the gauge invariance for the interaction. In the contribution of the mass-dimension-one fermion to the graviton propagator at one-loop level, we found the conditions for the cancellation of the tadpole term by a cosmological counterterm. We calculate the scattering process for arbitrary momentum. For low energies, the result reveals that only the scalar sector present in the vertex contributes to the gravitational potential. Finally, we evaluate the non-relativistic limit of the gravitational interaction and obtain an attractive Newtonian potential, as required for a dark-matter candidate.
|
Pi, M., Barranco, M., Navarro, J., & Ancilotto, F. (2012). Nucleation and cavitation in parahydrogen. Chem. Phys., 399, 213–217.
Abstract: We have used a density functional approach to investigate thermal homogeneous nucleation and cavitation in parahydrogen. The effect of electrons as seeds of heterogeneous cavitation in liquid parahydrogen is also discussed within the capillary model.
|