Minimal Zee model for lepton g−2{g-2} and WW-mass shifts

We present a unique Yukawa structure of the Zee model that can accommodate neutrino oscillation data, solves the muon ${g-2}$ problem, and explains the recent $W$ boson mass measurement. Our Yukawa structure is minimal in the sense that it contains the least possible number of parameters. In this minimal scenario, neutrino masses are quasidegenerate and are compatible with both normal and inverted orderings. The mixing angle $\theta_{23}$ is predicted to lie in the second (first) octant for normal (inverted) ordering. In both cases, the CP violating phase is close to 3$\pi/2$. The minimal texture also predicts a large branching fraction of the heavy neutral Higgs boson into a pair of electron and muon.Comment: 6 pages, 1 figure. v2 expanded introduction on LFV in the Zee model, references added, to be appeared on PRD. v3 corrected typos, matched PRD versio

Collider Constraints on a Dark Matter Interpretation of the XENON1T Excess

In light of the excess in the low-energy electron recoil events reported by XENON1T, many new physics scenarios have been proposed as a possible origin of the excess. One possible explanation is that the excess is a result of a fast moving dark matter (DM), with velocity $v\sim0.05-0.20$ and mass between 1 MeV and 10 GeV, scattering off an electron. Assuming the fast moving DM-electron interaction is mediated by a vector particle, we derive collider constraints on the said DM-electron interaction. The bounds on DM-electron coupling is then used to constrain possible production mechanisms of the fast moving DM. We find that the preferred mass of the vector mediator is relatively light ($\lesssim$ 1 GeV) and the coupling of the vector to the electron is much smaller than the coupling to the fast moving DM.Comment: 6 pages, 5 figures, references added, CMB constraints included, low-energy bounds updated, conclusion unchange

Effect of Nano-to Micro-Scale Surface Topography on the Orientation of Endothelial Cells

The effect of grating textures on the alignment of cell shape and intracellular actin cytoskeleton has been investigated in bovine aortic endothelial cells (BAECs) cultured on a model cross-linked poly(dimethylsiloxane) (PDMS). Grating-textured PDMS substrates, having a variation in channel depths of 200 nm, 500 nm, 1 µm and 5 µm, were coated with fibronectin (Fn) to promote endothelial cell adhesion and cell orientation. As cells adhered to the Fn-coated surface, the underlying grating texture has shown to direct the alignment of cell shape, F-actin and focal contacts parallel to the channels. Cell alignment was observed to increase with increasing channel depths, reaching the maximum orientation where most cells aligned parallel to channels on 1-µm textured surface. Immunofluorescence studies showed that F-actin stress fibers and vinculin at focal contacts also aligned parallel to the channels. Cell proliferation was found to be independent of grating textures and the alignment of cell shape was maintained at confluence

A New Higgs Boson with Electron-Muon Flavor-Violating Couplings

Recently, the CMS Collaboration performed a search on a new resonance decaying to $e^\pm\mu^\mp$ in the mass range of 110 GeV to 160 GeV. The search also hints a possible excess at 146 GeV with a $3.8\sigma~(2.8\sigma)$ of local (global) significance. Motivated by that, we try to interpret the results in the context of the type-III two-Higgs-doublet-model. We find that the excess is only moderately constrained by low-energy lepton-flavor-violation processes, in particular the $\mu\to e \gamma$ decay. We also compare the CMS bounds across the entire search region against constraints of $\mu\to e\gamma$ and $\mu\to e$ conversion in nuclei. Our finding indicates that the collider bounds can be superior to those of low-energy processes for the scalar mass between $110 \text{ GeV}$ and $150 \text{ GeV}$, suggesting the importance of this mass range for future searches.Comment: v1: 7 pages, 2 figures; v2 add compatibility analysis between CMS signal and ATLAS data, matched PLB versio

Massive spin-2 states as the origin of the top quark forward-backward asymmetry

We show that the anomalously large top quark forward-backward asymmetry observed by CDF and DØ can naturally be accommodated in models with flavor-violating couplings of a new massive spin-2 state to quarks. Regardless of its origin, the lowest-order couplings of a spin-2 boson to fermions are analogous to the coupling of the graviton to energy/momentum, leading to strong sensitivity of the effects associated with its virtual exchange to the energy scales at hand. Precisely due to this fact, the observed dependence of the asymmetry on the tt invariant mass fits nicely into the proposed framework. In particular, we find a vast parameter space which can lead to the central value for the observed forward-backward asymmetry in the high mass bin. © 2012 SISSA

Zee model with quasidegenerate neutrino masses and where to find it

We present a Zee model with a family dependent $$Z_2$$ symmetry for radiative neutrino masses. Our motivation is to get a model that correctly describes neutrino oscillation phenomena, while at the same time offers definite predictions. The imposed $$Z_2$$ symmetry greatly reduces the number of free parameters in the model. These parameters are then determined from the neutrino data, from which one can study its outcomes. Our setup only admits quasidegenerate neutrino masses with the sum of neutrino masses between 100 and 130 meV, the effective Majorana mass between 20 and 40 meV, and the effective electron neutrino mass between 48 and 53 meV. The ratio of the vacuum expectation values of the Higgs doublets, $$\tan \beta$$, is found to be $$\tan \beta \lesssim 0.5$$ and $$\tan \beta \gtrsim 10$$. The former is ruled out by lepton flavor violation (LFV) processes, such as $$\mu \rightarrow e\gamma$$ and $$\mu \rightarrow e$$ conversion, which are determined up to two loops. For the latter, these LFV processes are within reach of the next generation of experiments. Moreover, for $$\tan \beta \gtrsim 10$$, the couplings of heavy neutral scalars to dimuon are significant. If they are sufficiently light, i.e., $$\lesssim 200$$ GeV, collider search for their decays into muon pair provides a stronger constraint on most parts of the model parameter space than the LFV ones