arXiv subjects

Henrique Rubira

Publications and source records attributed to Henrique Rubira.

At least 19 recordsLinked to original sources

arXiv2026

Hot New Early Dark Energy: Dark Radiation Matter Decoupling

We present a microscopic model of the dark sector that resolves the Hubble tension within standard current data sets (Planck 2018, Pantheon+ and DESI DR2 BAO) based on well-known fundamental principles, gauge symmetry and spontaneous symmetry breaking. It builds on the Hot New Early Dark Energy (Hot NEDE) setup, featuring a dark $SU(N)$ gauge symmetry broken to $SU(N-1)$ in a supercooled phase transition that creates a thermal bath of self-interacting dark radiation in the epoch between Big Bang Nucleosynthesis and recombination. Adding a fermion multiplet charged under the gauge symmetry provides a naturally stable component of dark matter that interacts with dark radiation. Spontaneous symmetry breaking predicts a decoupling of this interaction once the dark sector cools down, that we refer to as dark radiation matter decoupling (DRMD). We also provide a simplified DRMD model that captures the essential features of the full theory while retaining additional falsifiable predictions. Using the data sets stated above, we find agreement with the SH${}_0$ES determination of $H_0$ at the 1.4$σ$ level, compared to a 5.7$σ$ tension in $Λ$CDM, thereby providing a resolution of the Hubble tension.

astro-ph.CO↗

arXiv2026

Two-loop renormalization and running of galaxy bias

We systematically extend the framework of galaxy bias renormalization to two-loop order. For the minimal complete basis of 29 deterministic bias operators up to fifth order in the density field and at leading order in gradient expansion we explicitly work out one- and two-loop renormalization. The latter is provided in terms of double-hard limits of bias kernels, which we find to depend on only one function of the ratio of the loop momenta. After including stochasticity in terms of composite operator renormalization, we apply the framework to the two-loop power spectrum of biased tracers and provide a simple result suitable for numerical evaluation. In addition, we work out one- and two-loop renormalization group equations (RGE) for deterministic bias coefficients related to bias operators constructed from a smoothed density field, generalizing previous works. We identify a linear combination of bias operators with enhanced UV sensitivity, related to a positive eigenvalue of the RGE. Finally, we present an analogy with the RGE as used in quantum field theory, suggesting that a resummation of large logarithms as employed in the latter may also yield useful applications in the study of large-scale galaxy bias.

astro-ph.CO↗

arXiv2026

Non-Gaussian Galaxy Stochasticity and the Noise-Field Formulation

We revisit the stochastic, or noise, contributions to the galaxy density field within the effective field theory (EFT) of large-scale structure. Starting from the general, all-order expression of the EFT partition function, we elucidate how the stochastic contributions can be described by local nonlinear couplings of a single Gaussian noise field. We introduce an alternative formulation of the partition function in terms of such a noise field, and derive the corresponding field-level likelihood for biased tracers. This noise-field formulation can capture the complete set of stochastic contributions to the galaxy density at the field level in a normalized, positive-definite probability density which is suitable for numerical sampling. We illustrate this by presenting the first results of EFT-based field-level inference with non-Gaussian and density-dependent stochasticity on dark matter halos using LEFTfield.

astro-ph.CO↗

arXiv2026

Galaxy bias renormalization: Two-loop Power Spectrum, One-loop Trispectrum and Bispectrum

We present a complete treatment of fifth-order renormalized galaxy bias at the one- and two-loop level in real space, including gradient corrections to deterministic bias operators at next-to-leading order. We then provide a complete computation of the two-loop power spectrum as well as the one-loop bispectrum and trispectrum of biased tracers, and demonstrate how to jointly model these statistics in a fully renormalized framework. These statistics also require stochastic renormalization of products of two, three or four operators at coincidence, which we include at leading order in gradients by means of an operator product expansion. We verify that all UV limits of loop integrals are absorbed by the counterterms we consider. Upon solving the resulting renormalization group equations, we find a pronounced scale-dependence of higher-gradient bias coefficients. Since our renormalization prescription is performed manifestly at the operator level, our results can also easily be extended to higher $N$-point functions, higher loop orders and field-level analyses.

astro-ph.CO↗

arXiv2026

Towards the Two-Loop EFTofLSS in Galaxy Lensing Surveys

Extracting cosmological information from Stage IV weak lensing surveys requires non-linear modelling of the matter power spectrum that is accurate across a broad range of scales and redshifts and robust to baryonic feedback. We forecast the application of the two-loop effective field theory of large-scale structure (EFTofLSS) to Roman Space Telescope, carefully considering parameterization, scale cuts, and priors. We develop neural network emulators for the two-loop integrals, allowing rapid evaluation of the likelihood. Weak lensing demands a continuous-in-redshift description of the EFT, potentially introducing tens of nuisance parameters. We address this by calibrating the counterterm redshift evolution against the Euclid Emulator 2 and accounting for the residual freedom in redshift with spline functions. A principal component analysis of the free parameters reduces the dimensionality to a few degrees of freedom that the data can constrain. Next, we calibrate the priors on those degrees of freedom by using a suite of hydrodynamical simulations. We forecast the $S_8$ constraints as a function of scale cuts, showing that the two-loop EFT with Roman cosmic shear provides unbiased $S_8=σ_8\sqrt{Ω_{\rm m}/0.3}$ constraints with relative errors of about $0.9\%$ and $1.4\%$ when allowing for $5\%$ and $1\%$ contamination from ultraviolet modes, respectively. The two-loop EFT improves the scale reach beyond the one-loop EFT and non-linear dark matter-only models when baryonic effects are included. This framework provides a robust path for extracting small-scale information from future cosmic shear data.

astro-ph.CO↗

arXiv2026

Rapid cosmological inference with the two-loop matter power spectrum

We compute the two-loop effective field theory (EFT) power spectrum of dark matter density fluctuations in $Λ$CDM using the recently proposed COBRA method (Bakx. et al, 2025). With COBRA, we are able to evaluate the two-loop matter power spectrum in $\sim 1$ millisecond at $ \sim 0.1 \%$ precision on one CPU for arbitrary redshifts and on scales where perturbation theory applies. As an application, we use the nonlinear matter power spectrum from the Dark Sky simulation to assess the performance of the two-loop EFT power spectrum compared to the one-loop EFT power spectrum at $z=0$. We find that, for volumes typical for Stage IV galaxy surveys, $V = 25 \,(\text{Gpc}/h)^3$, the two-loop EFT can provide unbiased cosmological constraints on $Ω_m,H_0$ and $A_s$ using scales up to $k_\text{max}=0.26\, h/\text{Mpc}$, thereby outperforming the constraints from the one-loop EFT ($k_\text{max}=0.11\, h/\text{Mpc}$). The Figure of Merit on these three parameters increases by a factor $\sim 2.6$ and the one-dimensional marginalized constraints improve by $\sim35\%$ for $Ω_m$, $\sim20\%$ for $H_0$ and $\sim 15\%$ for $A_s$.

astro-ph.CO↗

arXiv2025

Multi-tracer beyond linear theory

The multi-tracer (MT) technique has been shown to outperform single-tracer analyses in the context of galaxy clustering. In this paper, we conduct a series of Fisher analyses to further explore MT information gains within the framework of non-linear bias expansion. We examine how MT performance depends on the bias parameters of the subtracers, showing that directly splitting the non-linear bias generally leads to smaller error bars in $A_s$, $h$, and $ω_{\rm cdm}$ compared to a simple split in $b_1$. This finding opens the door to identifying subsample splits that do not necessarily rely on very distinct linear biases. We discuss different total and subtracer number density scenarios, as well as the possibility of splitting into more than two tracers. Additionally, we consider how different Fingers-of-God suppression scales for the subsamples can be translated into different $k_{\rm max}$ values. Finally, we present forecasts for ongoing and future galaxy surveys.

astro-ph.CO↗

arXiv2025

Gravitational waves from first-order phase transitions: from weak to strong

We study the generation of gravitational waves (GWs) during a cosmological first-order phase transition (PT) using the recently introduced Higgsless approach to numerically simulate the fluid motion induced by the PT. We present for the first time GW spectra sourced by bulk fluid motion in the aftermath of strong first-order PTs ($α= 0.5$), alongside weak ($α= 0.0046$) and intermediate ($α= 0.05$) PTs, previously considered in the literature. We find that, for intermediate and strong PTs, the kinetic energy in our simulations decays, following a power law in time. The decay is potentially determined by non-linear dynamics and hence related to the production of vorticity. We show that the assumption that the source is stationary in time, characteristic of compressional motion in the linear regime (sound waves), agrees with our numerical results for weak PTs, since in this case the kinetic energy does not decay with time. We then provide a theoretical framework that extends the stationary assumption to one that accounts for the time evolution of the source: as a result, the GW energy density is no longer linearly increasing with the source duration, but proportional to the integral over time of the squared kinetic energy fraction. This effectively reduces the linear growth rate of the GW energy density and allows to account for the period of transition from the linear to the non-linear regimes of the fluid perturbations. We validate the novel theoretical model with the results of simulations and provide templates for the GW spectrum for a broad range of PT parameters.

gr-qc↗

arXiv2024

The Renormalization Group for Large-Scale Structure: Origin of Galaxy Stochasticity

The renormalization group equations for large-scale structure (RG-LSS) describe how the bias and stochastic (noise) parameters -- both of matter and biased tracers such as galaxies -- evolve as a function of the cutoff $Λ$ of the effective field theory. In previous work, we derived the RG-LSS equations for the bias parameters using the Wilson-Polchinski framework. Here, we extend these results to include stochastic contributions, corresponding to terms in the effective action that are higher order in the current $J$. We derive the general local interaction terms that describe stochasticity at all orders in perturbations, and a closed set of nonlinear RG equations for their coefficients. These imply that a single nonlinear bias term generates all stochastic moments through RG evolution. Further, the evolution is controlled by a different, lower scale than the nonlinear scale. This has implications for the optimal choice of the renormalization scale when comparing the theory with data to obtain cosmological constraints.

astro-ph.CO↗

arXiv2024

Full-shape BOSS constraints on dark matter interacting with dark radiation and lifting the $S_8$ tension

In this work we derive constraints on interacting dark matter-dark radiation models from a full-shape analysis of BOSS-DR12 galaxy clustering data, combined with Planck legacy cosmic microwave background (CMB) and baryon acoustic oscillation (BAO) measurements. We consider a set of models parameterized within the effective theory of structure formation (ETHOS), quantifying the lifting of the $S_8$ tension in view of KiDS weak-lensing results. The most favorable scenarios point to a fraction $f\sim 10-100\%$ of interacting dark matter as well as a dark radiation temperature that is smaller by a factor $ξ\sim 0.1-0.15$ compared to the CMB, leading to a reduction of the tension to the $\sim 1σ$ level. The temperature dependence of the interaction rate favored by relaxing the $S_8$ tension is realized for a weakly coupled unbroken non-Abelian $SU(N)$ gauge interaction in the dark sector. To map our results onto this $SU(N)$ model, we compute higher-order corrections due to Debye screening. We find a lower bound $α_d\equiv g_d^2/(4π)\gtrsim 10^{-8} (10^{-9})$ for dark matter mass $1000 (1)$ GeV for relaxing the $S_8$ tension, consistent with upper bounds from galaxy ellipticities and compatible with self-interactions relevant for small-scale structure formation.

astro-ph.CO↗

arXiv2024

The Renormalization Group for Large-Scale Structure: Primordial non-Gaussianities

The renormalization group for large-scale structure (RG-LSS) describes the evolution of galaxy bias and stochastic parameters as a function of the cutoff $Λ$. In this work, we introduce interaction vertices that describe primordial non-Gaussianity into the Wilson-Polchinski framework, thereby extending the free theory to the interacting case. The presence of these interactions forces us to include new operators and bias coefficients to the bias expansion to ensure closure under renormalization. We recover the previously-derived ``scale-dependent bias'' contributions, as well as a new (subdominant) stochastic contribution. We derive the renormalization group equations governing the RG-LSS for a large class of interactions which account for vertices at linear order in $f_{\rm NL}$ that parametrize interacting scalar and massive spinning fields during inflation. Solving the RG equations, we show the evolution of the non-Gaussian contributions to galaxy clustering as a function of scale.

astro-ph.CO↗

arXiv2024

Hot New Early Dark Energy bridging cosmic gaps: Supercooled phase transition reconciles (stepped) dark radiation solutions to the Hubble tension with BBN

We propose a simple model that can alleviate the $H_0$ tension while remaining consistent with big bang nucleosynthesis (BBN). It is based on a dark sector described by a standard Lagrangian featuring a $SU(N)$ gauge symmetry with $N\geq3$ and a massive scalar field with a quartic coupling. The scalar acts as dark Higgs leading to spontaneous symmetry breaking $SU(N)\to SU(N\!-\!1)$ via a first-order phase transition à la Coleman-Weinberg. This set-up naturally realizes previously proposed scenarios featuring strongly interacting dark radiation (SIDR) with a mass threshold within hot new early dark energy (NEDE). For a wide range of reasonable model parameters, the phase transition occurs between the BBN and recombination epochs and releases a sufficient amount of latent heat such that the model easily respects bounds on extra radiation during BBN while featuring a sufficient SIDR density around recombination for increasing the value of $H_0$ inferred from the cosmic microwave background. Our model can be summarized as a natural mechanism providing two successive increases in the effective number of relativistic degrees of freedom after BBN but before recombination $ΔN_\mathrm{BBN} \to ΔN_\mathrm{NEDE} \to ΔN_\mathrm{IR}$ alleviating the Hubble tension. The first step is related to the phase transition and the second to the dark Higgs becoming non-relativistic. This set-up predicts further signatures, including a stochastic gravitational wave background and features in the matter power spectrum that can be searched for with future pulsar timing and Lyman-$α$ forest measurements.

astro-ph.CO↗

arXiv2023

Probing interacting dark sector models with future weak lensing-informed galaxy cluster abundance constraints from SPT-3G and CMB-S4

We forecast the sensitivity of ongoing and future galaxy cluster abundance measurements to detect deviations from the cold dark matter (CDM) paradigm. Concretely, we consider a class of dark sector models that feature an interaction between dark matter and a dark radiation species (IDM-DR). This setup can be naturally realized by a non-Abelian gauge symmetry and has the potential to explain $S_8$ tensions arising within $Λ$CDM. We create mock catalogs of the ongoing SPT-3G as well as the future CMB-S4 surveys of galaxy clusters selected via the thermal Sunyaev-Zeldovich effect (tSZE). Both datasets are complemented with cluster mass calibration from next-generation weak gravitational lensing data (ngWL) like those expected from the Euclid mission and the Vera C. Rubin Observatory. We consider an IDM-DR scenario with parameters chosen to be in agreement with Planck 2018 data and that also leads to a low value of $S_8$ as indicated by some local structure formation analyses. Accounting for systematic and stochastic uncertainties in the mass determination and the cluster tSZE selection, we find that both SPT-3G$\times$ngWL and CMB-S4$\times$ngWL cluster data will be able to discriminate this IDM-DR model from $Λ$CDM, and thus test whether dark matter - dark radiation interactions are responsible for lowering $S_8$. Assuming IDM-DR, we forecast that the temperature of the dark radiation can be determined to about 40% (10%) with SPT-3G$\times$ngWL (CMB-S4$\times$ngWL), considering 68% credibility, while $S_8$ can be recovered with percent-level accuracy. Furthermore, we show that IDM-DR can be discriminated from massive neutrinos, and that cluster counts will be able to constrain the dark radiation temperature to be below $\sim 10%$ (at 95% credibility) of the cosmic microwave background temperature if the true cosmological model is $Λ$CDM.

astro-ph.CO↗

arXiv2023

Machine Learning Post-Minkowskian Integrals

We study a neural network framework for the numerical evaluation of Feynman loop integrals that are fundamental building blocks for perturbative computations of physical observables in gauge and gravity theories. We show that such a machine learning approach improves the convergence of the Monte Carlo algorithm for high-precision evaluation of multi-dimensional integrals compared to traditional algorithms. In particular, we use a neural network to improve the importance sampling. For a set of representative integrals appearing in the computation of the conservative dynamics for a compact binary system in General Relativity, we perform a quantitative comparison between the Monte Carlo integrators VEGAS and i-flow, an integrator based on neural network sampling.

hep-th↗

arXiv2023

Galaxy bias renormalization group

The effective field theory of large-scale structure allows for a consistent perturbative bias expansion of the rest-frame galaxy density field. In this work, we present a systematic approach to renormalize galaxy bias and stochastic parameters using a finite cutoff scale $Λ$. We derive the differential equations of the Wilson-Polchinski renormalization group that describe the evolution of the finite-scale bias parameters with $Λ$, analogous to the $β$-function running in QFT. We further provide the connection between the finite-cutoff scheme and the renormalization procedure for $n$-point functions that has been used as standard in the literature so far; some inconsistencies in the treatment of renormalized bias in current EFT analyses are pointed out as well. The fixed-cutoff scheme allows us to predict, in a principled way, the finite part of loop contributions which is due to perturbative modes and which, in the standard renormalization approach, is absorbed into counterterms. We expect that this will allow for the robust extraction of (a yet-to-be-determined amount of) additional cosmological information from galaxy clustering, both when using field-level techniques and $n$-point functions.

astro-ph.CO↗

arXiv2023

The Effective Field Theory of Large-Scale Structure and Multi-tracer II: redshift space and realistic tracers

We extend the multi-tracer (MT) formalism of the effective field theory of large-scale structure to redshift space, comparing the results of MT to a single-tracer analysis when extracting cosmological parameters from simulations. We used a sub-halo abundance matching method to obtain more realistic multi-tracer galaxy catalogs constructed from N-body simulations. Considering different values for the sample shot noise and volume, we show that the MT error bars on $A_s$, $ω_{\rm cdm}$, and $h$ in a full-shape analysis are approximately $50\%$ smaller relative to ST. We find that cosmological and bias coefficients from MT are less degenerate, indicating that the MT parameter basis is more orthogonal. We conclude that using MT combined with perturbation theory is a robust and competitive way to accommodate the information present in the mildly non-linear scales.

astro-ph.CO↗

arXiv2023

Gravitational waves from defect-driven phase transitions: domain walls

We discuss the gravitational wave spectrum produced by first-order phase transitions seeded by domain wall networks. This setup is important for many two-step phase transitions as seen for example in the singlet extension of the standard model. Whenever the correlation length of the domain wall network is larger than the typical bubble size, this setup leads to a gravitational wave signal that is shifted to lower frequencies and with an enhanced amplitude compared to homogeneous phase transitions without domain walls. We discuss our results in light of the recent PTA hints for gravitational waves.

astro-ph.CO↗

arXiv2022

Higgsless simulations of cosmological phase transitions and gravitational waves

First-order cosmological phase transitions in the early Universe source sound waves and, subsequently, a background of stochastic gravitational waves. Currently, predictions of these gravitational waves rely heavily on simulations of a Higgs field coupled to the plasma of the early Universe, the former providing the latent heat of the phase transition. Numerically, this is a rather demanding task since several length scales enter the dynamics. From smallest to largest, these are the thickness of the Higgs interface separating the different phases, the shell thickness of the sound waves, and the average bubble size. In this work, we present an approach to perform Higgsless simulations in three dimensions, producing fully nonlinear results, while at the same time removing the hierarchically smallest scale from the lattice. This significantly reduces the complexity of the problem and contributes to making our approach highly efficient. We provide spectra for the produced gravitational waves for various choices of wall velocity and strength of the phase transition, as well as introduce a fitting function for the spectral shape.

astro-ph.CO↗