arXiv subjects

F. C. Correia

Publications and source records attributed to F. C. Correia.

6 recordsLinked to original sources

arXiv2023

Measuring the impact of green retrofits on CO$_2$ emissions: London Housing Case Study

The residential sector is responsible for approximately 20 percent of the world's energy-related greenhouse gas emissions. In order to improve this reality, it is essential to help and support the leading actor in this scene, the homeowner. In general, buildings are complex objects as each home may have very particular parameters: different materials (windows, walls, types of roofs, etc.), uses, and habits. No two cases are identical. In this paper, we addressed this problem by proposing a method to obtain estimates of energy and carbon savings resulting from a class of retrofit projects and housing profiles. We applied our formulas to conduct a case study of the London residential sector, supported by the publicly available Energy Performance Certificates (EPC) dataset. As a result of a multi-project renovation of a house, including loft insulation, double-glazed windows, and energy-efficient lighting (LED), we found that the average family in the Greater London area could save approximately 9 MWh in energy consumption, 1,700 kgCO$_2$ in carbon emissions and more than GBP 800 on the energy bills, over a year, in contrast to a cost of around GBP 9,000 (or a return on investment of 11 years). In another example, applying the method to calculate what is needed to install heat pumps in each house in London, a total of GBP 16.9 billion would be spent, leading to savings of GBP 450 million per year (return on investment of 37 years). Finally, an overall upgrade to loft insulation would cost London households GBP 1.4 billion, generating GBP 290 million in annual savings (a 5-year return on investment).

stat.AP↗

arXiv2019

Light Mediators in Anomaly Free $U(1)_X$ Models I - Theoretical Framework

We examine theoretical features of $U(1)_X$ extensions of the Standard Model whose quantum anomalies are canceled per generation. Similarly to other versions, the theory consists of a Two-Higgs-Doublet Model plus a scalar singlet embedded into the $SM \otimes U(1)_X$ gauge group, and introduces small modifications to the $Z$-boson interactions. These changes can be minimized by exclusively charging right-handed fermions under the new Abelian symmetry, and are compensated by the neutral $X$-boson exchange. Non-universality of fermion couplings can also be achieved by requiring one single $X$-charged family. In general, $X$ gauge bosons can be separated into $A'$ (dark photons) and $Z'$ subsets, distinguished by the presence of axial-vector currents. $A'$ physics is commonly simpler to constrain and therefore favored by experimental tests. Finally, the model can be UV completed both by stable $χ$ fermions or by right-handed neutrinos. The prior case may provide cold WIMPs in the theory.

hep-ph↗

arXiv2019

Light Mediators in Anomaly Free $U(1)_X$ Models II - Constraints on Dark Gauge Bosons

We consider experimental constraints in the MeV region in order to determine the parameter space for the $U(1)_X$ extension of the Standard Model, presented in the first part of our work. In particular, we focus on the model UV-completed by cold WIMPs. We conclude that the electron anomalous magnetic moment, the neutrino trident production and the relic abundance $Ω_{CDM}$ provide the most stringent bounds and, in particular cases, they are sufficient to exclude dark-photon ($A'$) models. By allowing the axial-vector coupling of the dark gauge boson $Z'$, the interference effect with the SM gauge bosons may reduce the bounds coming from the trident neutrino production. At the same time, such coupling allows a region of the parameter space already favored both by the relic abundance and by the discrepancy between experimental result and theoretical prediction for the muon anomalous magnetic moment. We emphasize that light-$Z'$ interactions, non-universal for the two first lepton families, necessarily create a difference in the proton charge radius measured in the Lamb shift of the $e$-hydrogen and $μ$-hydrogen. Finally, we determine the effects of the new gauge boson on the forward-backward asymmetry in $e^+ e^- \rightarrow \bar{f} f$, $f = μ, τ$, and on the leptonic decays $M \rightarrow j ν_j l^+ l^-$, where $M = π, K, D, D_s, B$ and $j,l = e, μ$.

hep-ph↗

arXiv2017

Fundamentals of the 3-3-1 Model with Heavy Leptons

The work is a brief review of the theory based on the $SU(3)_c \otimes SU(3)_L \otimes U(1)_X$ gauge group in the presence of Heavy Leptons. Recent analysis have established a set of four possible variants for the 3-3-1HL, whose content arises according to the so-denoted variable $β$. Since it has been argued about the presence of stable charged particles in this sort of models, we divide the different sectors of the Lagrangian between universal and specific vertices, and conclude that the omission of $β$-dependent terms in the potential may induce to a discrete symmetry for the versions defined by $|β|=\sqrt{3}$. In the context of $|β|=\frac{1}{\sqrt{3}}$, where the new degrees of freedom have the same standard electric charges, additional Yukawa interactions may create decay channels into the SM sector. Furthermore, we introduce a method of diagonalization by parts in the Scalar sector motivated by a general consequence of the Goldstone theorem. In summary, we develop the most complete set of terms allowed by the symmetry group and resolve their definitive pieces in order to justify the model description present in the literature.

hep-ph↗

arXiv2016

Restrained Dark $U(1)_d$ at Low Energies

We investigate a spontaneously broken $U(1)_d$ gauge symmetry with a muon-specific dark Higgs. Our first goal is to verify how the presence of a new dark Higgs, $ϕ$, and a dark gauge boson, $V$, can simultaneously face the anomalies from the muon magnetic moment and the proton charge radius. Secondly, by assuming that $V$ must decay to an electron-positron pair, we explore the corresponding parameter space determined with the low energy constraints coming from $ K \to μX$, electron $(g-2)_e$, $K \to μν_μe^+ e^-$, $K \to μν_μμ^+ μ^-$, $τ\to ν_τμν_μe^+ e^-$. We focus in the scenario where the $V$ mass is below $ \sim 2 m_μ$ and the $ϕ$ mass runs from few MeV till $250$ MeV, with V-photon mixing of the order $ \sim\mathcal{O}(10^{-3})$. Among weak process at low energies, we check the influence of the new light vector on kaon decays as well as on the scattering $e^+ e^- \rightarrow μ^+ μ^- e^+ e^-$ and discuss the impact of the dark Higgs on $e^+ e^- \rightarrow μ^+ μ^- μ^+ μ^- $. Finally, we consider contributions of the V-photon mixing in the decays $π^0 \to γe^+ e^-$, $η\to γe^+ e^-$, $ρ\to πe^+ e^-$, $K^* \to K e^+ e^-$ and $ϕ(1020) \to ηe^+ e^-$.

hep-ph↗

arXiv2015

Neutral meson mixing induced by box diagrams in the 3-3-1 model with heavy leptons

We consider in the 3-3-1 model with heavy leptons the box contributions to the mass difference in $K$ and $B$ neutral mesons induced by neutral (pseudo)scalars, exotic charged quarks, singly and doubly charged scalar and gauge bosons. In particular, we include the effects of a real scalar with mass near 125 GeV but with non-diagonal couplings to quarks. We show that, as in the tree level case, there are ranges of the parameters in which these contributions can be enough suppressed by negative interference among several amplitudes. Hence, in this model these $ΔF=2$ processes may be dominated by the standard model contributions. In addition, our results are valid in the minimal 3-3-1 model without the sextet.

hep-ph↗