Search

Left-right symmetric models which employ a generalized seesaw mechanism to generate quark and charged lepton masses are known to solve the strong CP problem via parity symmetry, without the need for the axion. These models lead to naturally light Dirac neutrinos with their masses arising through radiatve corrections. In this work, we show how baryogenesis via Dirac leptogenesis can be implemented in this framework. A pair of left-right symmetric scalar doublets $\phi_{L,R}$ carrying $(B-L)$ charge of $3$ is introduced for this purpose, which preserves the parity solution to the strong CP problem. Small neutrino masses are generated through one-loop diagrams mediated by these scalars. The decay of vector-like leptons ($E_i$) involved in the seesaw mechanism to generate charged lepton masses, $E_i \rightarrow \overline{\nu}_{jR} \,\phi_R^-$, creates a right-handed neutrino ($\nu_{R}$) asymmetry, while preserving total lepton number. The compensating lepton asymmetry is converted to baryon asymmetry via electroweak sphalerons. We show that for a large range of model parameters successful baryogenesis can be realized, with the $W_R^\pm$ gauge boson mass being as low as $10^6$ GeV., Comment: 21 pages, 7 figures and 2 tables

In this work, we present a unified theoretical framework that simultaneously addresses some of the most intriguing puzzles in particle physics and cosmology, namely the origins of neutrino mass, baryon asymmetry, and cosmic inflation. In our model, inflation is driven by a combination of the Standard Model Higgs, the type II seesaw Higgs responsible for neutrino mass generation, and the unified symmetry-breaking Higgs field. During inflation, non-zero values of the latter field ensure the absence of the monopole problem. The baryon asymmetry is generated through the Affleck-Dine mechanism, facilitated by the non-zero angular motion in the phase of a complex scalar field, which is part of the inflaton. We find that the successful parameter region for generating baryon asymmetry through a renormalizable term in the scalar potential requires a rather heavy type II seesaw triplet, with a mass well beyond the TeV scale. Inflationary observables, in particular, the spectral index is in excellent agree with experimental observation, whereas tensor-to scalar ratio is expected to be probed by the future LiteBIRD and CMB-S4 missions., Comment: 9 pages, 3 figures and 1 table

Supercooled first-order phase transition (FOPT) can lead to the formation of primordial black holes (PBHs). This scenario imposes stringent requirements on the profile of the effective potential. In this work, we use the singlet extended Standard Model (xSM) as a benchmark model to investigate this possibility at the electroweak scale. The PBHs formed during a supercooled FOPT have a narrow mass distribution around the mass of Earth. This distribution is closely tied to the temperature at which the PBHs form, corresponding to the FOPT at the electroweak scale. This scenario can be probed with microlensing experiments, space-based gravitational wave detectors, and collider experiments. Remarkably, the future space-based gravitational wave detector LISA will hold the potential to either confirm this PBH scenario in the xSM or completely rule it out for extremely small total dark matter fraction made of PBHs, down to $f_{\rm PBH}> 10^{-300}$. Interestingly, our findings suggest that PBHs within the xSM framework may align with observations of the six ultrashort timescale events reported by the OGLE microlensing experiment., Comment: 46 pages, 12 figures and 1 table

Theories in which the dark matter (DM) candidate is a fermion transforming chirally under a gauge symmetry are attractive, as the gauge symmetry would protect the DM mass. In such theories, the universe would have undergone a phase transition at early times that generated the DM mass upon spontaneous breaking of the gauge symmetry. In this paper, we explore the gravitational wave signals of a simple such theory based on an $\mathrm{SU}(2)_\mathrm{D}$ dark sector with a dark isospin-$3/2$ fermion serving as the DM candidate. This is arguably the simplest chiral theory possible. The scalar sector consists of a dark isospin-$3$ multiplet which breaks the $\mathrm{SU}(2)_\mathrm{D}$ gauge symmetry and also generates the DM mass. We construct the full thermal potential of the model and identify regions of parameter space which lead to detectable gravitational wave signals, arising from a strong first-order $\mathrm{SU}(2)_\mathrm{D}$ phase transition, in various planned space-based interferometers, while also being consistent with dark matter relic abundance. Bulk of the parameter space exhibiting detectable gravitational wave signals in the model also has large WIMP-nucleon scattering cross sections, $\sigma_{\rm SI}$, which could be probed in upcoming direct detection experiments., Comment: 19 pages, 3 figures and 1 table, Matches the published version

SO(10) grand unified theory with minimum parameters in the Yukawa sector employs the Peccei-Quinn symmetry that solves the strong CP problem. Such an economical Yukawa sector is highly appealing and has been extensively studied in the literature. However, when the running of the renormalization group equations of the Yukawa couplings are considered, this scenario shows somewhat tension with the observed fermion masses and mixing. In this work, we propose an extension of the minimal framework that alleviates this tension by introducing only a few new parameters. The proposed model consists of a fermion in the fundamental and a scalar in the spinorial representations. While the latter is needed to implement the Peccei-Quinn symmetry successfully, the presence of both is essential in obtaining an excellent fit to the fermion mass spectrum. In our model, axions serve the role of dark matter, and the out-of-equilibrium decays of the right-handed neutrinos successfully generate the matter-antimatter symmetry of the Universe., Comment: 14 pages+references, 1 figure, 1 table: Matches with published version, Comments are welcome

This study explores the generation of the observed baryon asymmetry of the Universe within the complex Two Higgs Doublet Model (C2HDM) while considering theoretical and current experimental constraints. In our investigation, we analyze critical elements of the Higgs potential to understand the phase transition pattern. Specifically, we examine the formation of the barrier and the uplifting of the true vacuum state, which play crucial roles in facilitating a strong first-order phase transition. Furthermore, we explore the potential gravitational wave signals associated with this phase transition pattern and investigate the parameter space points that can be probed with LISA. Finally, we compare the impact of different approaches to describing the bubble profile on the calculation of the baryon asymmetry. We contrast the typically used kink profile approximation against the explicit solution of the tunneling profile. We find that a non-negligible range of the C2HDM parameter space results in significant discrepancies in the baryon asymmetry estimation between these two approaches. Through an examination of the parameter space, we identify a benchmark point that satisfies the observed baryon asymmetry., Comment: 31 pages, 8 figures, 1 table, match the published version in PRD

The dynamics of electroweak phase transition could have profound consequences for particle physics and cosmology. We study the prospects for the HL-LHC to probe the strong first-order electroweak phase transition (SFOEWPT) regime in the type-I 2HDM. We focus on the Higgstrahlung channel $pp\to ZH/A$ with a resonant top-quark pair final state $H/A\to t\bar t$. We find that the top-quark pair final state renders the largest sensitivity to the SFOEWPT regime, in comparison to the other Higgstrahlung searches already performed by ATLAS and CMS, that focus on the $H/A\to bb$ and $H\to WW$ final states. We also derive the complementarity of the Higgstrahlung searches with other relevant classes of searches at the HL-LHC and compare them with the gravitational wave sensitivity at LISA., Comment: 25 pages, 9 figures; v2: match to published version

We study the gravitational wave imprints of left-right symmetric model equipped with universal seesaw mechanism allowing for the natural generation of hierarchical masses of the Standard Model fermions. The scalar sector of this model is the minimal one, consisting of only two Higgs doublets. Following the construction of the full thermal potential for this model, we perform a scan of the entire parameter space and identify the region in which the cosmic phase transition associated with the left-right symmetry breaking gives gravitational wave signals detectable by a variety of planned space-based interferometers. Then we also discuss the relevant collider implications of this beyond the Standard Model scenario., Comment: 21 pages + references, 6 figures, references added, matches published version

The knowledge of the Higgs potential is crucial for understanding the origin of mass and the thermal history of our Universe. We show how collider measurements and observations of stochastic gravitational wave signals can complement each other to explore the multiform scalar potential in the two Higgs doublet model (2HDM). Accounting for theoretical and current experimental constraints, we analyze the key ingredients in the shape of the Higgs potential triggering the transmutation in phase transition, from the smooth crossover to the strong first-order phase transition ($\xi_c>1$), focusing on the barrier formation and the upliftment of the true vacuum. In particular, we observe that the $\xi_c>1$ regime is favored for lower scalar masses, rendering strong extra motivation for collider searches. We contrast the dominant collider signals at the HL-LHC (high-luminosity LHC) with observable gravitational wave signals at LISA. We obtain that the HL-LHC will be able to cover a vast range of the $\xi_c>1$ parameter space, with scalar decays to heavy fermions $(H,A,H^\pm\to tt, tb)$ being the most promising smoking gun signature of a strong first-order electroweak phase transition in the 2HDM., Comment: 23 pages, 13 figures, comments are welcome! v2: match to the published version