We discuss the modes $B\to K^{(*)}\nu\bar\nu$ in the context of non-standard neutrino interactions and in the presence of new light (dark matter) particle pairs and consider the implications for additional $B$ decay modes. In particular, we consider the possibility of accommodating the new Belle II measurement.
Triality models are motivated by flavour structure theories. They produce charged lepton flavour violation channels mediated by a doubly charged scalar. However, the triality charges forbid decays such as muon to electron conversions, avoiding stringent experimental bounds. We have calculated predictions of charged lepton violation in this scenario and show the complementarity between Belle II...
In this presentation, I will discuss lepton and baryon number violation using an Effective Field Theory (EFT) approach. In particular, in the first part of the talk, I will analyse the generation of tree-level Majorana neutrino masses by the introduction of new scalar multiplets at the electroweak scale, which acquire vacuum expectation values (VEVs). We will elucidate the underlying UV...
Fifty years after the discovery of QCD experimental and theoretical efforts continue to uncover structures in its spectrum - sometimes unexpectedly. In the heavy sector alone, for example, among the about 62 (LHCb'22) new hadron states observed, many are 4- or 5-quark states. These states are phenomenologically difficult to explain and conclusions are often contradictory depending on how QCD...
We propose a leptogenesis scenario where the CP asymmetry is provided by the kinetic motion of the majoron in the decay and inverse decay of a right-handed neutrino which violates the lepton number by one unit. We find that successful leptogenesis can be achieved for sub-keV majoron which can be a viable dark matter candidate as well. If one considers a very strong wash-out regime requiring a...
Without tuning of parameters, the typical mass scale of the lightest right-handed neutrino (RHN), in the thermal leptogenesis paradigm, is about 10^{11} GeV. As opposed to the mild departure from equilibrium offered by the slow expansion, a first-order phase transition (FOPT) offers a drastic scenario of out-of-equilibrium dynamics. In this work we explore the possibility of embedding thermal...
We investigate the pseudo-Nambu-Goldstone bosons (pNGBs) potential in the geometrical point of view. In this talk I will discuss how to essentially organise or structurally understand the pNGB potential without recourse to the UV symmetries.
We study the phenomenological signatures associated with a light fermiophobic Higgs boson within the type-I two-Higgs-doublet model at the HL-LHC. Our exhaustive parameter scan revealed a captivating mass range between 1 GeV and 10 GeV. This range retains a substantial number of viable parameter points, primarily due to the current experimental difficulties in probing soft decay products of...
A singlet majoron can arise from the seesaw framework as a pseudo-Goldstone boson when the heavy Majorana neutrinos acquire masses via the spontaneous breaking of global U(1)_L symmetry. The resulting cosmological impacts are usually derived from the effective majoron-neutrino interaction, and the majoron abundance is accumulated through the freeze-in neutrino coalescence. However, a...
Recently, experiments for long-lived particle search are recently focused on from both theoretical and experimental points of views. This kind of experiment has advantages of low background and high luminosity and can explore light particles beyond the Standard Model (BSM) feebly coupled to the SM particles. In my talk, I explain the recent works about the explorations of the BSM physics at...
A systematic study of one-loop contributions to the decay channels h→ll¯γ with l=νe,μ,τ,e,μ, performed in Higgs extended versions of the Standard Model, is presented in the 't Hooft-Veltman gauge. Analytic formulas for one-loop form factors are expressed in terms of the logarithm and di-logarithmic functions. As a result, these form factors can be reduced to those relating to the loop-induced...
The scalar sector of the 3-3-1 model with axion like particle is studied in detail. In the model under consideration, there are two kinds of scalar fields: the bilepton scalars carrying lepton number two and the ordinary ones without lepton number. We show that there is no mixing among these two kinds of scalar fields. We analyze in detail the CP-odd scalar sector of the model to find the...
We discuss a possibility to solve fine-tuning problems based on micro-canonical formulation of quantum field theory.
Scattering Amplitudes are crucial to understanding the range of validity of effective field theories. In this talk I will talk about the unitarity and validity of extra dimensional gravity and demonstrate that the Goldstone Boson Equivalence Theorem ensures that high energy scattering of massive Kaluza-Klein states are unitary through a series of Ward Identities. Furthermore I will show that...
In this talk, I will present a new model of DM where the DM is a composite of a spontaneously broken conformal field theory. The DM is a thermal relic with its abundance determined by the freeze-out of annihilations to dilatons, the Goldstone boson of broken conformal symmetry. If the dilaton is heavier than the DM this is an example of forbidden DM. I will present a fully realistic model that...
In this talk, I will first try to discuss why the particle nature of dark matter is one of the most important topics of the modern physics from the historical development and frontier research of dark matter, and whether the evidence for dark matter reveals only gravitational interaction. Then, I will take one of the simplest dark matter models - mirror dark matter (the dark sector behaves...
Supernova neutrino boosted dark matter (SNν BDM) and its afterglow effect stand as promising signatures for exploring beyond Standard Model (bSM) physics. The unique time-evolution feature of SNν BDM offers a direct avenue for inferring DM mass, concurrently leading to substantial background reduction with increasing sensitivity. In this talk, I will expound upon the SNν BDM framework...
We explore a novel possibility that dark matter has a light mass below 1 GeV in a lepton portal dark matter model. There are Yukawa couplings involving dark matter, left-handed leptons and an extra scalar doublet in the model. In the light mass region, dark matter is thermally produced via its annihilation into neutrinos. In order to obtain the correct relic abundance and avoid collider...
Ultralight bosonic fields (ULBFs) are predicted by various theories beyond the standard model of particle physics and are viable candidates of cold dark matter. There have been increasing interests to search for the ULBFs in physical and astronomical experiments. In this paper, we investigate the sensitivity of several planned space-based gravitational-wave interferometers to ultralight scalar...
Dark Matter candidates with cross sections as tiny as can be captured efficiently in compact stars, like Neutron Stars and White Dwarfs. The collisions to capture Dark Matter would heat the star, raising its equilibrium temperature, around 2000K for a NS. Thus, observation of old and cold NS that should have reached equilibrium can be used to set constraints on the capture cross section. In...
Celestial bodies are well motivated laboratories for dark matter searches. I will give two such examples. In the first scenario, dark matter gets captured in the Earth by scattering with Earth nuclei. The accumulated dark matter annihilates and yields excessive heat. In the other scenario, dark photons resonantly convert to photons in the atmosphere of neutron stars or white dwarfs, producing...
We introduce the gauged quintessence model, in which the dark energy field (quintessence) has a U(1) gauge symmetry. We identify the real part of the complex scalar as the dark energy field (quintessence), while the imaginary part is the longitudinal component of a new gauge boson. It brings interesting characters to dark energy physics. The U(1) gauge boson can affect the quintessence...
In this work, we explore the intriguing possibility of connecting self-interacting dark matter (SIDM) with the recently observed exceptionally bright and long-duration Gamma Ray Burst (GRB221009A). The proposed minimal scenario involves a light scalar mediator, simultaneously enabling dark matter (DM) self-interaction and explaining the observed very high energy (VHE) photons from GRB221009A...
We investigate a minimal renormalizable model that incorporates a light fermionic weakly interacting massive particle (WIMP) dark matter (DM) and a mediator for interactions with standard model particles. Our comprehensive likelihood analysis considers constraints from direct detection experiments, collider searches, cosmological observations, and astrophysical observations. In particular, we...
511 keV gamma-ray excess from the Galactic center is a long lasting anomaly without satisfying astrophysical explanation. Hawking evaporation of hypothetical primordial black hole (PBH) with mass ${\color{blue}1.0\times 10^{-17} \lesssim M_{\rm PBH}/M_\odot \lesssim 8.0\times 10^{-17}}$ and fractional abundance ${\color{blue}10^{-3} \lesssim f_{\rm PBH} \lesssim 1.0}$, gives rise substantial...
In my talk I will discuss our recent work in studying the prospects to look for Dark Matter in Gravitational Wave Detectors, in particular in KAGRA. While the prospects for conventional particle Dark Matter are rather bleak, it might be possible to detect heavy (kg-scale) Dark Matter. If time allows, I will also briefly comment on other peoples work looking for very light Dark Matter in KAGRA.
This study investigates the classical Higgs inflation model with a modified Higgs potential fea- turing a dip. We examine the implications of this modification on the generation of curvature perturbations, stochastic gravitational wave production, and the potential formation of primordial black holes (PBHs). Unlike the classical model, the modified potential allows for enhanced power spectra...
We assessed the sensitivity of SKA-like pulsar timing measurements to probe signals of a first order phase transition (FOPT) scenario in the dark sector, which gives rise to primordial black holes (PBHs) and stochastic gravitational waves (GWs). We considered the mechanism where the PBHs are formed from the collapse of Fermi balls created from dark matter filtered out of true vacuum bubbles....
I shall discuss gravitational wave signatures coming from a single-field inflation model in which the inflaton couples to the Gauss-Bonnet term. When the scalar potential term and the Gauss-Bonnet coupling term have different signs, a nontrivial fixed point arises, effectively inducing ultra slow-roll inflation. In this case, primordial black holes can form, together with enhanced...
First order phase transitions are well-motivated and extensively studied sources of gravitational waves (GWs) from the early Universe. The vacuum energy released during such transitions is assumed to be transferred primarily either to the expanding walls of bubbles of true vacuum, whose collisions source GWs, or to the surrounding plasma, producing sound waves and turbulence, which act as GW...
We study the interaction of several types of static straight cosmic strings, including local strings, global strings, and bosonic superconducting strings with and without magnetic currents. First, we evaluate the interaction energy of two widely separated cosmic strings using the point source formalism and show that the most dominant contribution to the interaction energy comes from the...
The advent of using Gravitational Waves (GW) as a powerful method to understand the evolution of our early universe has arrived. In this talk, I will present an example of how the reheating temperature can be constrained only from GW coming from the Standard Model of Particle Physics plasma of the early universe both in Standard Cosmology and in a particular Gauss-Bonnet Scenario. In addition,...
We study the solar emission of light dark sector particles that self-interact strongly enough to self-thermalize. The resulting outflow behaves like a fluid which accelerates under its own thermal pressure to highly relativistic bulk velocities in the solar system. Compared to the ordinary noninteracting scenario, the local outflow has at least ~10^3 higher number density and correspondingly...
While the properties of the observed Higgs boson agree with the Standard Model predictions, the hierarchy of fermion masses lacks an explanation within the model. In this work, we propose a fresh approach to this problem, involving a different Higgs doublet responsible for each quark mass. We construct a model with a gauged, non-anomalous $U(1)$ family symmetry that fixes which fermion couples...
I will describe some recent developments on using gravitational waves in searches for BSM: from phase transitions in the early universe, to searches of topological defects at LIGO, and searches for dark matter with gravitational waves.
Astrometry holds the potential for testing fundamental physics through the effects of the Stochastic Gravitational Wave Background (SGWB) in the ∼1−100 nHz frequency band on precision measurements of stellar positions. Such measurements are complementary to tests made possible by the detection of the SGWB using Pulsar Timing Arrays. Here, the feasibility of using astrometry for the...
