arXiv subjects

P. R. S. Carvalho

Publications and source records attributed to P. R. S. Carvalho.

25 records · Page 2Linked to original sources

arXiv2019

NLO critical exponents of O($N$) lambda $ϕ^{4}$ scalar field theories in curved spacetime

In this paper we investigate analytically the conformal symmetry influence on the next-to-leading order radiative quantum corrections to critical exponents for massless O($N$) $λϕ^{4}$ scalar field theories in curved spacetime. We renormalize the theory by applying the BPHZ method. We find that the critical exponents are the same as that of flat spacetime, at least at the loop order considered. We argue that this result agrees perfectly with the universality hypothesis.

hep-th↗

arXiv2018

Parameter estimation for a Lorentz invariance violation

We employ techniques from quantum estimation theory (QET) to estimate the Lorentz violation parameters in the 1+3-dimensional flat spacetime. We obtain and discuss the expression of the quantum Fisher information (QFI) in terms of the Lorentz violation parameter $σ_0$ and the momentum k of the created particles. We show that the maximum QFI is achieved for a specific momentum $k_{\mathrm{max}}$. We also find that the optimal precision of estimation of the Lorentz violation parameter is obtained near the Planck scale.

gr-qc↗

arXiv2018

Critical exponents and amplitude ratios of scalar nonextensive $q$-field theories

We compute the radiative quantum corrections to the critical exponents and amplitude ratios for O($N$) $λϕ^{4}$ scalar high energy nonextensive $q$-field theories. We employ the field theoretic renormalization group approach through six methods for evaluating the high energy nonextensive critical exponents up to next-to-leading order while the high energy nonextensive amplitude ratios are computed up to leading level by applying three methods. Later we generalize these high energy nonextensive finite loop order results for any loop level. We find that the high energy nonextensive critical exponents are the same when obtained through all the methods employed. The same fact occurs for the high energy nonextensive amplitude ratios. Furthermore, we show that these high energy nonextensive universal quantities are equal to their low energy extensive counterparts, thus showing that the nonextensivity is broken down at high energies.

hep-th↗

arXiv2018

Unconventional minimal subtraction and Callan-Symanzik methods for Lorentz-violating scalar field theories at all loop orders

We present an explicit analytical computation of the quantum corrections, at next-to-leading order, to the critical exponents. We employ for that the Unconventional minimal subtraction, recently proposed, and the Callan-Symanzik methods to probe the universality hypothesis by comparing the outcomes for the critical exponents evaluated in both methods and the ones calculated previously in massless theories renormalized at different renormalization schemes. Furthermore, the consistency of the former method is investigated for the first time in literature, to our knowledge. At the end, we compute the critical exponents at any loop level by an induction process and furnish the physical interpretation of the results.

hep-th↗

arXiv2018

Probing the two-scale-factor universality hypothesis by exact rotation symmetry-breaking mechanism

We probe the two-scale factor universality hypothesis by evaluating, firstly explicitly and analytically at the one-loop order, the loop quantum corrections to the amplitude ratios for O($N$) $λϕ^{4}$ scalar field theories with rotation symmetry-breaking in three distinct and independent methods in which the rotation symmetry-breaking mechanism is treated exactly. We show that the rotation symmetry-breaking amplitude ratios turn out to be identical in the three methods and equal to their respective rotation symmetry-breaking ones, although the amplitudes themselves, in general, depend on the method employed and on the rotation symmetry-breaking parameter. At the end, we show that all these results can be generalized, through an inductive process based on a general theorem emerging from the exact calculation, to any loop level and physically interpreted based on symmetry ideas.

hep-th↗

arXiv2018

Critical properties of scalar field theory with Lorentz violation: Exact treatment of Lorentz-violating mechanism

In this work, we compute analytically the infrared divergences of massless O($N$) self-interacting scalar field theories with Lorentz violation, which are exact in the Lorentz-violating $K_{μν}$ coefficients, for evaluating the corresponding next-to-leading order critical exponents. For that, we apply three distinct and independent field-theoretic renormalization group methods. We find that the outcomes for the critical exponents are the same in the three methods and, furthermore, are identical to their Lorentz invariant counterparts. We generalize the results for all loop levels by employing a general theorem arising from the exact procedure and give the corresponding physical interpretation.

hep-th↗

arXiv2018

Asymptotic single-particle states and exact Lorentz-violating all-loop quantum corrections for scalar field theory

We perform the all-loop renormalization of the O($N$) $λϕ^{4}$ scalar field theory with Lorentz violation which is exact in the Lorentz-violating $K_{μν}$ coefficients. This task is fulfilled analytically firstly explicitly at next-to-leading order and later at all loop levels through an induction process based on a general theorem emerging from the exact approach. We show that the exact results reduce to the approximated ones, previously obtained, in the appropriated limit and comment on their implications. The current exact calculation involving such a symmetry breaking mechanism in the referred theory is the first one in literature for our knowledge. At the end, we analyze the effect of Lorentz violation on the asymptotic single-particle states.

hep-th↗