Constraining effective equation of state in f(Q, T) gravity

Abstract

New high-precision observations are now possible to constrain different gravity theories. To examine the accelerated expansion of the Universe, we used the newly proposed f(Q, T) gravity, where Q is the non-metricity, and T is the trace of the energy–momentum tensor. The investigation is carried out using a parameterized effective equation of state with two parameters, m and n. We have also considered the linear form of $$f(Q,T)= Q+bT$$ f ( Q , T ) = Q + b T , where b is constant. By constraining the model with the recently published 1048 Pantheon sample, we were able to find the best fitting values for the parameters b, m, and n. The model appears to be in good agreement with the observations. Finally, we analyzed the behavior of the deceleration parameter and equation of state parameter. The results support the feasibility of f(Q, T) as a promising theory of gravity, illuminating a new direction towards explaining the Universe dark sector.

Quantum Cosmology in $f(Q)$ theory

“…where we have chosen the set of canonical variables in (38) for which q ≥ 0 when the F (q) of ( 39) is real. Note that the expression (40) does not imply p q ≈ 0 since this corresponds through (38) to a zero scale factor.…”

“…where we have chosen the set of canonical variables in (38) for which q ≥ 0 when the F (q) of ( 39) is real. Note that the expression (40) does not imply p q ≈ 0 since this corresponds through (38) to a zero scale factor. The latter is a trivial solution of the Euler-Lagrange equations (19), which however makes singular the spacetime metric and thus it is not acceptable.…”

“…where for the sector λ > 1 2 we take the upper signs of (38), while for λ < 1 2 we consider the lower ones. In this way q is never negative, as also happens with Q.…”

“…We notice that the value q = 0 corresponds to either Q = 0 or Q = 1 3σ , which are the values of the classical solution. Given that, due to the transformation (38) to be real, apart from q we also need Q ≥ 0, we obtain the following possibilities by inverting (54):…”

“…In this sense a geometric description is attributed to the dark energy. The most common geometric invariants which have been introduced by cosmologists are functions and derivatives of: the Ricci scalar [25][26][27], the torsion scalar of teleparallelism [28], the scalar, Q, of the nonmetricity tensor [29] and many others [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46].…”