I have proposed a simple model with (light) dark matters (DMs)
that interact with leptons via Yukawa couplings, with S. Okawa and S. Iguro.
The DMs can evade strong bounds from the DM direct detection experiments
and predict some specific signals at the LHC. In this talk, I review the work shortly, and
introduce a model with $SU(3)\times SU(2)_L \times SU(2)_R \times U(1)_{B-L} $ gauge...
Photons can mix with low-mass bosons in the presence of external electromagnetic fields. A known example is the hypothetical axion (spin 0) which can couple with the photon by a two-photon vertex. Other axion-like particles (ALP) have been proposed in many Beyond Standard Model (BSM) theories. In this talk we give a brief overview of the physics of axion and discuss the possibility of...
In recent years, very weak interactions on the MeV scale, in particular the case of U(1) Lmu-Ltau, have attracted significant attention in the context of muon g-2, dark matter-mediated forces and others. This presentation will focus on how the extension of this U(1) symmetry to five dimensions can be explored in future new physics search experiments, concretely, the DUNE experiment and future...
I will present a variant of the 3HDM, referred to as the BGL-3HDM, incorporating a horizontal U(1)×U(1) symmetry, which can distinguish the primary sources of mass for different fermion generations. In the version considered here, the Yukawa matrices in the down-quark and charged lepton sectors are diagonal, thereby eliminating tree-level FCNCs in these sectors. FCNC interactions mediated by...
In the theory with a Majorana fermion coupled to quarks via a dimension-six four-fermion vector-vector interaction, we show that the observed baryon asymmetry of the Universe can be generated in the decay and scattering processes in the expanding early Universe. In viable parts of parameter space we discuss the observability of neutrino-antineutron oscillation in upcoming experiments.
Flavor experiments commissioned to provide precise measurements of the Standard Model (SM) parameters are excellent laboratories to look for hypothesised particles, especially those with masses less than a GeV. In this talk, I discuss some experiments related to semi-leptonic charged current amplitudes, which can be veritable smoking guns for axion-like particles (ALPs). I show that the...
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. In our investigation, we analyze critical elements of the Higgs potential to...
In this talk, I will discuss the physics potential of ESSnuSBplus setup on behalf of the ESSnuSB collaboration. ESSnuSB is an upcoming neutrino oscillation experiment to be based in Sweden. The ESSnuSBplus set up will consist of three neutrino sources i.e., the main neutrino beam from the ESS linac, low energy neutrinos from a monitored beam (LEMNB), and low energy neutrinos from a muon...
A multi-boson door into compositeness
In an effective field theory approach, we have considered a minimal extension of Standard Model is extended by a non-renormalizable dimension six operator of the form respecting the symmetries of the Standard Model. Such an operator can affect the dynamics of Higgs field and the electroweak phase transition. Presence of such term modifies the triple Higgs coupling. Constraint on the scale...
Self-organizing map (SOM), a special class of artificial neural network (ANN),
has found extensive application in many science branches since its discovery in 1982 by
Teuvo Kohonen. Inspired by the ability of the brain to map smells, sounds, images, etc., to
different neurons in a self-organizing way and segregate them concerning their similarity,
SOM is widely used for dimensional...
We propose a novel and comprehensive particle physics framework that addresses multiple cosmological tensions observed in recent measurements of the Hubble parameter, $S_8$, and Lyman-$\alpha$ forest data. Our model, termed `{SIDR+z_t}' (Self Interacting Dark Radiation with transition redshift), is based on an inelastic dark matter (IDM) scenario coupled with dark radiation, governed by a...
The singlet-doublet vector-like fermion dark matter model has been extensively studied in the literature over the past decade. An important parameter in this model is the singlet-doublet mixing angle ($\sin\theta$). All the previous studies have primarily focused on annihilation and co-annihilation processes for obtaining the correct dark matter relic density, assuming that the singlet and...
We study the most minimal scalar extension that offers a tree-level violation of the custodial symmetry, while containing a dark matter (DM) candidate. A hypercharge-less scalar triplet that obtains a small vev breaks the custodial symmetry, which translates to the charged component $T^\pm \to Z W^\pm$ decay. Adding an inert singlet to this extension as a stable DM also opens up the fully...
The singlet-doublet dark matter model is one of the most studied WIMP scenarios to realize the relic of DM in a large parameter space. In this work, we study the two-step leptogenesis in the singlet-doublet Majorana dark matter model. We extend the Standard Model (SM) by introducing three Majorana singlet fermions ($N_i$), three doublet fermions ($\Psi_i$), and a singlet scalar ($\Phi$), all...
Finding high-likelihood regions in BSM scenarios, particularly in high-dimensional models is a computationally expensive task and inefficient task using conventional statistical methods, due to the curse of dimensionality. In this work, we implement a generative framework, Real-valued Non-Volume Preserving(RealNVP) Normalizing Flows as our Machine Learning(ML) framework to assist Nested...
We propose a GeV-scale self-interacting dark matter (SIDM) candidate within a $U(1)_D$ extension of the Standard Model (SM), addressing small-scale structure anomalies in $\Lambda$CDM while predicting an observable contribution to $\Delta N_{\rm eff}$. The model introduces a fermionic DM candidate $\chi$ and a scalar $\phi$, both charged under an unbroken $U(1)_D$ gauge symmetry. The...
Neutrino oscillation measurements via long-baseline experiments rely on the accurate measurement of neutrino interactions with the nucleus and subsequent reconstruction of the neutrino energy. A signature of charged-current (CC) neutrino interaction in the detector is the lepton in the final state and further event classification of CC events in detectors is done based on the composition of...
Quantum coherence plays a crucial role in the dynamics of neutral meson systems, aiding in the extraction of various Standard Model parameters. However, real physical systems inevitably interact with their environments, leading to decoherence effects. In the case of neutral B mesons, this decoherence is modeled using a single parameter, $\lambda$. It is important to reassess the Standard Model...
The observation of neutrino oscillations implies the existence of flavour violation in the charged lepton sector. The branching ratios of various charged lepton flavour-violating (CLFV) decay modes are influenced by the underlying neutrino mass model. This study investigates the correlations between radiative CLFV decays and meson CLFV decays within the framework of the three simple seesaw...
We study two novel aspects of democratic 3HDMs -- the custodial limit and the possibility of wrong-sign Yukawa couplings. In the custodial limit, the democratic 3HDMs can easily negotiate the constraints from the electroweak T-parameter. We also uncover the possibility of having wrong-sign Yukawa couplings in democratic 3HDMs, as in the case of 2HDMs. We show that a democratic 3HDM encompasses...
Sterile neutrinos, hypothetical singlet fermions, interact with ordinary matter only through mixing with active neutrinos. In core-collapse supernovae, their production via Mikheyev-Smirnov-Wolfenstein (MSW) resonances of electron neutrinos and antineutrinos can influence explosion dynamics and nucleosynthesis. We probe the effect of these kinds of MSW conversions on the fast flavor...
We study the possibility of producing axion dark matter (DM) via misalignment mechanisms in a non-standard cosmological era dominated by ultra-light primordial black holes (PBH). While the effect of PBH domination on the production of axion via vacuum misalignment is known assuming the PBH evaporation to proceed according to Hawking’s semi-classical (SC) approximation, we go beyond these...
In this presentation we discuss the effect of neutrino oscillation in presence of curved spacetime. The influence of curvature on fermionic fields is described by the spin connection, which consists of two components: a universal gravitational term and a non-universal contorsion term. The contraction of contorsion with tetrad fields, which serves as a link between the internal flat space...
Prediction of spectral index from the temperature fluctuation of Cosmic Microwave Background (CMB) can play a pivotal role in predicting the reheating dynamics in the early Universe. In this work, we consider α-attractor model of inflation and investigate the reheating phenomena in conjunction with the production of dark matter from the thermal bath via a dimension five operator. The...
Large SU(3) breaking has been observed in some hadronic B decays. This observation may eventually pave the way for challenging Standard Model inspired hypotheses in these decay modes. I will provide an update on these hadronic anomalies. I will include additional decay channels that may also shed light on this new puzzle.
In this talk, I will discuss the impact of preheating on baryogenesis in Higgs-Starobinsky inflation. I will show that if the Ricci scalar couples with the U(1) hypercharge density, it can explain the observed matter-antimatter asymmetry of the Universe.
CP-violation is essential for understanding the matter-antimatter asymmetry in the Universe and serves as a key component of physics beyond the Standard Model (SM). Extensions in the Higgs sector permit CP violations beyond the CKM phase. However, the origin of CP-violation remains unknown, as both spontaneous and explicit violations are feasible. In this talk, I present the phenomenological...
New Physics, if weakly coupled to the Standard Model, is often easier to search at the electron-positron machines, than at the LHC. In this talk, I will discuss a few examples concerning dark matter, Higgs effective operators, lepton number and flavor violating interactions.
A color octet isodoublet can have esoteric origins and it complies with minimal flavour violation. In this study, we take a scenario where the well known Type-X Two-Higgs doublet model is augmented with a color octet isodoublet. We shed light on how such a setup can predict the recently observed value for the W-boson mass. The two-loop Barr-Zee contributions to muon g-2 stemming from the...
"Dark matter direct detection is now standing at an interesting juncture, where the SM neutrino background and the upper bound on dark matter signal cross section are starting to overlap in a region of DM mass $\sim 10$~GeV.
The neutrino floor, which defines the extent of the neutrino background, can get modified in different BSM set up. We work in a BSM set up that is a very natural dark...
We analyze various dark matter models featuring additional scalars and fermions. The scalar quartic and Yukawa couplings play key roles in achieving the correct relic density via Freeze-out and Freeze-in mechanisms. In addition to the SM-like high-scale minimum along the Higgs direction, new minima can arise along the extended scalar direction, depending on the dark matter parameter space. We...
A multi-boson door into compositeness
