Neutrinos having a non-zero mass is our first laboratory evidence for New Physics. Yet the absolute mass scale remains unknown. Cosmology plays a fundamental role, as it sets the world-leading constraint and, in the near future, it should measure the exact value.
However, any cosmology inference is indirect. So, what are we really measuring with current cosmological data?
In this talk, I...
We investigate the doublet variant left-right symmetric model (LRSM) using the cosmic microwave background (CMB). The masses of neutrinos and other fermions are determined solely by their interactions with the Higgs bidoublet in this model. Light neutrinos, as Dirac particles, introduce additional relativistic degrees of freedom that interact in the early universe, particularly in the right...
Axion-like particles (ALPs) decaying before the time of recombination can have strong implications in a range of cosmological and astrophysical observations. In this talk I present a global analysis of a model of decaying ALP, focusing specifically on their coupling to photons. Exploiting the multidisciplinary nature of the GAMBIT framework, we combine state-of-the-art calculations of the...
A cosmological network of axion strings in our Universe today may leave its imprint on the polarization pattern of the cosmic microwave background radiation through the phenomenon of axion-string-induced birefringence. I will explain how this signal arises, discuss how it depends on the properties of the string network and the axion-photon coupling, describe how existing measurements of...
In this talk, I will discuss the latest efforts to constrain the mass of the ultra-light dark matter models, focusing on the current bounds of the fuzzy dark matter (FDM) model. I will show how we can use the different predictions of this model and different astrophysical systems to put the strongest bounds to date on the mass of this ultra-light axion, showing also the incompatibilities that...
Dark matter may exist as an ultralight bosonic particle, leading to the formation of an ever-present field that could interact with us via a new long-range fifth force. Recently, quantum sensing techniques have been shown to be promising avenues with which to detect such a dark matter candidate. However, these studies did not entirely capture the stochastic nature of the field, which is...
We revisit the Affleck-Dine leptogenesis via the $L H_u$ flat direction with a light slepton field. Although the light slepton field is favored in low-energy SUSY phenomenologies, such as the muon $g-2$ anomaly and bino-slepton coannihilation, it may cause a problem in the Affleck-Dine leptogenesis: it may create an unwanted charge-breaking vacuum in the Affleck-Dine field potential so that...
A Strong First-Order Electroweak Phase Transition (SFOEWPT) is a necessary ingredient for Electroweak Baryogenesis (EWBG) to explain the observed Baryon asymmetry of the Universe. Supersymmetric models with singlet extensions can easily accommodate single or multi-step first-order phase transitions (FOPT). In this work, we examine the dynamics of an SFOEWPT and the possibility of EWBG by...
Determination of the nature of dark matter is one of the most fundamental problems of particle physics and cosmology. This talk presents recent searches for dark matter particles from the CMS experiment at the Large Hadron Collider. The results are obtained from the proton-proton collision data at the center of mass energy of 13 TeV collected during the LHC Run 2.
I will discuss about the halo-independent bounds on the WIMP-nucleon couplings of the non-relativistic effective Hamiltonian that drives the scattering off nuclei of a WIMP of spin 1/2. We will see that for most of the couplings the degree of relaxation of the halo-independent bounds compared to those obtained assuming the Standard Halo Model is with few exceptions relatively moderate in the...
FIMP dark matter is produced via the freeze-in mechanism that generally implies tiny coupling between the DM and the standard model particles, making DM direct detection and collider searches almost hopeless. This is not the case for a DM at low reheating temperatures, where direct detection plays a fundamental role in constraining the parameter space. We show the viability of a scalar and a...
Numerous studies have led to upper limits on the dark matter annihilation cross-section assuming only single exclusive annihilation channels. We consider a more realistic situation and present a study taking into account the complete annihilation pattern within a given particle physics model. This allows us to study the impact on the derived upper limits on the dark matter annihilation...
We study the production of Dark Matter (DM) in a minimal freeze-in model during inflationary reheating. We analyze the case where a heavier parent particle decays into DM and a Standard Model fermion in two reheating scenarios: bosonic reheating (BR) and fermionic reheating (FR). Firstly, we show that for low reheating temperatures, BR and FR scenarios predict different lifetimes and masses...
Primordial Black Holes (PBHs) may form in the early universe, from the gravitational collapse of large density perturbations, generated by large quantum fluctuations during inflation. Since PBHs form from rare over-densities, their abundance is sensitive to the tail of the primordial probability distribution function (PDF) of the perturbations. It is therefore important to calculate the full...
We have shown that the process of non-instantaneous reheating during the post-inflationary period can have a sizeable impact on the charged lepton equilibration temperature in the early Universe. This suggests a relooking into the flavor effects of leptogenesis where the production and decay of right-handed neutrinos take place within this extended era of reheating. We observe that the decay...
After a brief introduction to phase transitions and explain why they are worth studying, I will examine those in the minimal extension of the SM using a real singlet scalar field. The uniqueness of our study lies in the identification and detailed analysis of a parameter space region where a first-order phase transition with relativistic expanding bubbles can occur. This particular region is...
We consider Dark Matter (DM) production via the freeze-in mechanism with finite temperature corrections. Freeze-in is mostly sensitive to temperatures corresponding to the highest energy scale involved in the production reactions, contrary to the freeze-out paradigm, which occurs well within a non-relativistic regime. As a result, quantum and finite temperature corrections can significantly...
We delve deeper into the potential composition of dark matter as stable scalar glueballs from a confining dark $SU(N)$ gauge theory, focusing on $N=\{3,4,5\}$. To predict the relic abundance of glueballs for the various gauge groups and scenarios of thermalization of the dark gluon gas, we employ a thermal effective theory that accounts for the strong-coupling dynamics in agreement with...
Global non-topological solitons (Q-balls) exist when the potential of a charged scalar field grows slower than quadratically. At zero temperature, this requires attractive interactions. We first show that finite temperature effects can generate the necessary terms even in the absence of attractive interactions at zero temperature. As a result, non-topological solitons exist at finite...
Based on the recent article [2023.02399], we discuss the LISA potential for finding evidence of New Physics from measurements of the Stochastic GW Background (SGWB). As a benchmark scenario, we study a version of the low-scale Majoron model equipped with lepton number symmetry and an inverse seesaw mechanism for neutrino mass generation. In particular, we discuss under which circumstances the...
Cosmological phase transitions that are strongly first order are well motivated in physics beyond the standard model, for example as part of an electroweak baryogenesis solution to the matter anti-matter asymmetry, and could give rise to an observable gravitational wave spectra. Based on https://arxiv.org/abs/2305.02357 and https://arxiv.org/abs/2212.07559 I discuss various subtle issues in...
We discuss a dark photon model with successive symmetry breaking $\mathrm{SU(2)_D}$ $\to$ $\mathrm{U(1)_D}$ $\to$ $\mathbb{Z}_2$ in the dark sector. Various dark topological defects appear, such as monopoles, dyons, strings and beads. They are shown to induce QED electromagnetic fields through kinetic and magnetic mixing between $\mathrm{U(1)_{QED}}$ and $\mathrm{U(1)_D}$. In particular, dark...
We discuss the interplay of First Order Electroweak Phase Transitions (FOEWPT), Triple Higgs Couplings (THCs) and Gravitational Waves (GWs) in the 2 Higgs Doublet Model (2HDM). We identify six thermal histories in the 2HDM, out of which one leads to a FOEWPT. We discuss the implications for GWs and the measurement of THCs at the HL-LHC and future $e^+e^-$ colliders, such as the ILC.
The recent observation of $^4$He favors a large lepton asymmetry at the big bang nucleosynthesis. If Q-balls with a lepton charge decay after the electroweak phase transition, such a large lepton asymmetry can be generated without producing too large baryon asymmetry. In this scenario, Q-balls dominate the universe before the decay and induce the sharp transition from the early...
I will talk about how to distinguish the nature of neutrino masses, Dirac vs Majorana, from the spectrum of gravitational waves generated. I will discuss two simple models of Majorana and Dirac mass genesis motivated by generating small neutrino masses without assuming tiny Yukawa couplings. For Majorana neutrinos, spontaneous breaking of the gauged $U(1)_{B−L}$ symmetry gives a cosmic string...
The sound shell source from a cosmic phase transition is a compelling explanation for the stochastic gravitational wave background recently seen by various PTA collaborations. I discuss motivations for such a phase transition as well as comparing the sound shell model using the full velocity profile, as opposed to the broken power law that results from using the rms fluid velocity. Finally I...
I will review different ideas to probe leptogenesis with gravitational waves caused by first-order phase transitions or cosmic strings. In particular, I will focus on local cosmic strings produced after the breaking of a U(1)_(B-L) gauge symmetry that gives masses to right-handed neutrinos. Cosmic strings are expected to produce a stochastic gravitational background that could be probed...
Monopoles are inevitable predictions of GUT theories. They are produced during phase transitions in the early universe, but also mechanisms like Schwinger effect in strong magnetic fields could give relevant contributions to the monopole number density. I will show that from the detection of intergalactic magnetic fields of primordial origin we can infer additional bounds on the magnetic...
The Peccei-Quinn solution to the strong CP problem has a problematic aspect: it relies on a global U(1) symmetry which, although broken at low energy by the QCD anomaly, must be an extremely good symmetry of high-energy physics. This issue is known as the Peccei-Quinn quality problem. We propose a model where the Peccei-Quinn symmetry arises accidentally and is respected up to high-dimensional...
We study the prospect of simultaneous explanation of tiny neutrino masses, dark matter (DM), and the observed baryon asymmetry of the Universe in a $Z_3$-symmetric complex singlet scalar extended type-II seesaw model. The complex singlet scalar plays the role of DM. Analyzing the thermal history of the model, we identify the region of the parameter space that can generate a first-order...
The momentum distribution of the non-thermal dark matter produced during reheating is assumed to be the same as that at production, red-shifted at later times due to the expansion of the Universe. In this talk we show that, in such a scenario, DM self scatterings as well as scatterings with the SM bath via inflaton mediated processes are inevitable, which can have substantial impact on the...
Ultra-low mass primordial black holes (PBH) which may briefly dominate the energy density of the universe but completely evaporate before the big bang nucleosynthesis (BBN), may lead to interesting observable signatures. We propose a novel test of this scenario by detecting its characteristic doubly peaked gravitational wave (GW) spectrum in future GW observatories. Here the first-order...
The lack of information before Big Bang Neucleosynthesis (BBN) allow us to assume the presence of a new species $\phi$ whose energy density redshifts as $a^{-(4+n)}$ where $n>0$ and $a$ is the scale factor. In this non-standard cosmological setup, we have considered $U(1)_{L_\mu-L_\tau} \otimes U(1)_X$ gauge extension of the Standard Model (SM) and studied different phases of the cosmological...
