The challenge of monochromatization

The FCC-ee could measure the electron Yukawa coupling in a dedicated run at $$\sim $$ ∼ 125 GeV collision energy, provided that the center-of-mass (CM) energy spread can be reduced by means of monochromatization, e.g., through introducing nonzero horizontal dispersion of opposite sign at the interaction point (IP), for the two colliding beams. If the IP dispersion is nonzero, beamstrahlung blows up the horizontal emittance, and self-consistent IP parameters need to be determined. Two configurations are being studied. The first uses crab cavities to establish effective head-on collisions. The second configuration maintains the standard FCC-ee crossing angle, which, together with the IP dispersion, introduces a correlation between the local collision energy and the longitudinal location inside the detector, thereby allowing for an integrated scan of the Higgs resonance curve. We compare both approaches.

Generalized 2HDM with wrong-sign lepton-Yukawa coupling, in light of $$g_{\mu }-2$$ and lepton flavor violation at the future LHC

To explain the observed muon anomaly and simultaneously evade bounds from lepton flavor violation in the same model parameter space is a long-cherished dream. In view of a generalized Two Higgs Doublet Model, with a Yukawa structure as a perturbation of Type-X, we are able to get substantial parameter space satisfying these criteria. In this work, we focus on a region with “wrong-sign” lepton-Yukawa coupling which gives rise to interesting phenomenological consequences. Performing a simple cut-based analysis, we show that at 14 TeV run of the LHC with $$300 \mathrm{{fb}}^{-1}$$ 300 fb - 1 integrated luminosity, part of the model parameter space can be probed with significance "Equation missing" which further improves with Artificial Neural Network analysis.

CP-Violation in a composite 2-Higgs doublet model

We study CP-Violation (CPV) in a Composite 2-Higgs Doublet Model (C2HDM) based on the global symmetry breaking SO(6)/[SO(4) × SO(2)], wherein the strong sector is modeled by a two-site moose structure. Non-trivial complex phases in the interactions involving fermions in both the elementary and strong sectors can induce CPV in the Higgs potential as well as the Yukawa coupling parameters. We compute both of the latter and analyse their dependence upon the aforementioned complex phases. Finally, we discuss physics observables which are distinctive of this model. Even in the simplest case with only one complex phase in the strong sector we can get significant CPV effects.

Broken scaling neutrino mass matrix and leptogenesis based on A4 modular invariance

In this work, we have proposed a modular A4 symmetric model of neutrino mass which, simultaneously, explains observed baryon asymmetry of the Universe (BAU). In minimal extension of the standard model (SM) with two right-handed neutrinos we work in a supersymmetric framework. At Type-I seesaw level, the model predicts scaling in the neutrino mass matrix. In order to have correct low energy phenomenology, we propose two possible scenarios of scale-breaking in the neutrino mass matrix emanating from Type-I seesaw. Scenario-1 is based on the dimension-5 Weinberg operator whereas scenario-2 implements Type-II seesaw via scalar triplet Higgs superfields (∆,$$ \overline{\Delta } $$ ∆ ¯ ). Interestingly, the breaking patterns in both, otherwise dynamically different scenarios, are similar which can be attributed to the same charge assignments of superfields (∆,$$ \overline{\Delta } $$ ∆ ¯ ) and the Higgs superfield Hu under modular A4 symmetry. The breaking is found to be proportional to the Yukawa coupling of modular weight 10 ($$ {Y}_{1,1\prime}^{10} $$ Y 1 , 1 ′ 10 ). We, further, investigates the predictions of the model under scenario-2 (Type-I+II) for neutrino mass, mixings and matter-antimatter asymmetry of the Universe. The model predicts normal hierarchical neutrino masses and provide a robust range (0.05 − 0.08)eV for sum of neutrino masses (Σmi). Lepton number violating 0νββ decay amplitude (Mee) is obtained to lie in the range (0.04 − 0.06)eV. Future 0νββ decay experiments such as NEXT and nEXO shall pose crucial test for the model. Both CP conserving and CP violating solutions are allowed in the model. Interesting correlations are obtained, specially, between Yukawa couplings of modular weight 2 and complex modulus τ. Contrary to $$ {Y}_2^2 $$ Y 2 2 and $$ {Y}_3^2 $$ Y 3 2 , the Yukawa coupling $$ {Y}_1^2 $$ Y 1 2 is found to be insensitive to τ and thus to CP violation because complex modulus τ is the only source of CP violation in the model. We, also, investigate the prediction of the model for BAU. The model exhibit consistent explanation of BAU for right-handed Majorana neutrino mass scale in the range ((1 − 5) × 1013) GeV.

Calculation of the Top-Quark Yukawa coupling constant

In this work, we study meson systems consisting of quark–antiquark. We solve Lippman–Schwinger equation numerically for heavy meson systems. We attempt to find a nonrelativistic potential model through which we can solve the quark–antiquark bound state problem. The coefficients obtained are in agreement with Martin potential coefficients. Via this method we also determine the strong coupling constant of Cornell and Yukawa potentials for the heavy meson.

Radiative neutrino masses, lepton flavor mixing and muon g − 2 in a leptoquark model

We propose a leptoquark model with two scalar leptoquarks $$ {S}_1\left(\overline{3},1,\frac{1}{3}\right) $$ S 1 3 ¯ 1 1 3 and $$ {\tilde{R}}_2\left(3,2,\frac{1}{6}\right) $$ R ˜ 2 3 2 1 6 to give a combined explanation of neutrino masses, lepton flavor mixing and the anomaly of muon g − 2, satisfying the constraints from the radiative decays of charged leptons. The neutrino masses are generated via one-loop corrections resulting from a mixing between S1 and $$ {\tilde{R}}_2 $$ R ˜ 2 . With a set of specific textures for the leptoquark Yukawa coupling matrices, the neutrino mass matrix possesses an approximate μ-τ reflection symmetry with (Mν)ee = 0 only in favor of the normal neutrino mass ordering. We show that this model can successfully explain the anomaly of muon g − 2 and current experimental neutrino oscillation data under the constraints from the radiative decays of charged leptons.

Yukawa coupling unification in an SO(10) model consistent with Fermilab (g − 2)μ result

We investigate the Yukawa coupling unification for the third generation in a class of SO(10) unified models which are consistent with the 4.2 σ deviation from the standard model of the muon g − 2 seen by the Fermilab experiment E989. A recent analysis in supergravity grand unified models shows that such an effect can arise from supersymmetric loops correction. Using a neural network, we further analyze regions of the parameter space where Yukawa coupling unification consistent with the Fermilab result can appear. In the analysis we take into account the contributions to Yukawas from the cubic and the quartic interactions. We test the model at the high luminosity and high energy LHC and estimate the integrated luminosities needed to discover sparticles predicted by the model.