Searcharxiv⌕ Search

arXiv subjects

Marcus B. Pinto

Publications and source records attributed to Marcus B. Pinto.

22 records · Page 2Linked to original sources
arXiv2001

Transition Temperature for Weakly Interacting Homogeneous Bose Gases

We apply the non-perturbative optimized linear $δ$ expansion method to the O(N) scalar field model in three-dimensions to determine the transition temperature of a dilute homogeneous Bose gas. Our results show that the shift of the transition temperature, $ΔT_c/T_c$, of the interacting model, compared with the ideal gas transition temperature, really behaves as $γa n^{1/3}$ where $a$ is the s-wave scattering length and $n$ is the number density. For $N= 2$ our calculations yield the value $γ= 3.059$.

cond-mat.stat-mech↗
arXiv1999

A Nonperturbative Study of Inverse Symmetry Breaking at High Temperatures

The optimized linear $δ$-expansion is applied to multi-field $O(N_1) \times O(N_2)$ scalar theories at high temperatures. Using the imaginary time formalism the thermal masses are evaluated perturbatively up to order $δ^2$ which considers consistently all two-loop contributions. A variational procedure associated with the method generates nonperturbative results which are used to search for parameters values for inverse symmetry breaking (or symmetry nonrestoration) at high temperatures. Our results are compared with the ones obtained by the one-loop perturbative approximation, the gap equation solutions and the renormalization group approach, showing good agreement with the latter method. Apart from strongly supporting inverse symmetry breaking (or symmetry nonrestoration), our results reveal the possibility of other high temperature symmetry breaking patterns for which the last term in the breaking sequence is $O(N_1-1) \times O(N_2-1)$.

hep-ph↗
arXiv1999

High Temperature Resummation in the Linear $δ$-Expansion

The optimized linear $δ$-expansion is applied to the $λϕ^4$ theory at high temperature. Using the imaginary time formalism the thermal mass is evaluated perturbatively up to order $δ^2$. A variational procedure associated with the method generates nonperturbative results which are used to obtain the critical temperature for the phase transition. Our results are compared with the ones given by propagator dressing methods.

hep-ph↗