Contrary to common perception, we show that the current Higgs data does not eliminate the possibility of a sequential fourth generation that get their masses through the same Higgs mechanism as the first three generations. The inability to fix the sign of the bottom-quark Yukawa coupling from the available data plays a crucial role in accommodating a chiral fourth generation which is consistent wi

Flavor symmetries à la Froggatt-Nielsen provide a compelling way to explain the hierarchies of fermionic masses and mixing angles in the Yukawa sector. In supersymmetric (SUSY) extensions of the Standard Model where the mediation of SUSY breaking occurs at scales larger than the breaking of flavor, this symmetry must be respected not only by the Yukawas of the superpotential but also by the soft-b

We propose a model where neutrino masses are generated at three loop order but neutrinoless double beta decay occurs at one loop. Thus we can have large neutrinoless double beta decay observable in the future experiments even when the neutrino masses are very small. The model receives strong constraints from the neutrino data and lepton flavor violating decays, which substantially reduces the numb

A vast literature on the theory and phenomenology of two-Higgs-doublet models (2HDM) exists since long. However, the present situation demands a revisit of some 2HDM properties. Now that a 125 GeV scalar resonance has been discovered at the LHC, with its couplings to other particles showing increasing affinity to the Standard Model Higgs-like behaviour, the 2HDM parameter space is more squeezed th

We show that in the Higgs triplet model, after the Higgs discovery, the mixing angle in the CP-even sector can be strongly constrained from unitarity. We also discuss how large quantum effects in h→γγ may arise in a Standard-Model-like scenario and a certain part of the parameter space can be ruled out from the diphoton signal strength. Using T-parameter and diphoton signal strength measurements,

We impose an S3 symmetry on the quark fields under which two of three quarks transform like a doublet and the remaining one as singlet, and use a scalar sector with the same structure of SU(2) doublets. After gauge symmetry breaking, a Z2 subgroup of the S3 remains unbroken. We show that this unbroken subgroup can explain the approximate block structure of the CKM matrix. By allowing soft breaking

In two-Higgs-doublet models with exact Z2 symmetry, putting mh ≃ 125 GeV at the alignment limit, the following limits on the heavy scalar masses are obtained from the conditions of unitarity and stability of the scalar potential: mH, mA, mH+ < 1 TeV and 1/8 < tan β < 8. The constraints from b → sγ and neutral meson mass differences, when superimposed on the unitarity constraints, put a tighter low

We show that the 2.4σ signal of the leptonic flavor violating (LFV) Higgs boson decay h→μτ, as observed by the CMS Collaboration recently, can be explained by a certain class of two-Higgs doublet models that allow controllable flavor-changing neutral current with a minimal number of free parameters. We postulate that (i) the alignment limit is maintained, which means the lightest neutral scalar (h

Vilka nya konsumtionsformat växer fram inom den kollaborativa ekonomin och hur förhåller dessa sig till en normativ konsumtionskultur? Bidraget diskuterar tre olika exempel på hur olika former för delande - med lånepraktiker i centrum - kan organiseras och vilka normer och värderinhgar som är knutna till dessa.

We study the conditions required to make the two-Higgs-doublet-model (2HDM) scalar potential stable up to the Planck scale. The lightest CP-even scalar is assumed to have been found at the LHC and the alignment limit is imposed in view of the LHC Higgs data. We find that ensuring stability up to scales 1010GeV necessitates the introduction of a soft breaking parameter in the theory. Even then, som

A large class of two- and three-Higgs-doublet models with discrete symmetries has been employed in the literature to address various aspects of flavor physics. We analyze how the precision measurement of the Higgs to diphoton signal strength would severely constrain these scenarios due to the nondecoupling behavior of the charged scalars, to the extent that in the presence of exact discrete symmet

We demonstrate that light charged and extra neutral scalars in the (100-200) GeV mass range pass the potentially dangerous flavor constraints in a particular class of two-Higgs-doublet model which has appropriately suppressed flavor-changing neutral currents at tree level. We study their decay branching ratios into various fermionic final states and comment on the possibility of their detection in

We investigate the scalar potential of a general S3-symmetric three-Higgs-doublet model. The outcome of our analysis does not depend on the fermionic sector of the model. We identify a decoupling limit for the scalar spectrum of this scenario. In view of the recent LHC Higgs data, we show our numerical results only in the decoupling limit. Unitarity and stability of the scalar potential demand tha

We analyze the scalar sector properties of a general class of two-Higgs-doublet models which has a global U(1) symmetry in the quartic terms. We find constraints on the parameters of the potential from the considerations of unitarity of scattering amplitudes, the global stability of the potential and the p-parameter. We concentrate on the spectrum of the non-standard scalar masses in the decouplin

Prompted by the recent observation of a Higgs-like particle at the CERN Large Hadron Collider, we investigate a quantitative correlation between possible departures of the gauge and Yukawa couplings of this particle from their Standard Model expectations and the scale of unitarity violation in the processes WW→WW and tt̄→WW.

The shortest time interval controlled by a human being is the duration of a light pulse as short as only 100 attoseconds, i.e., 10-16 s. This "attosecond" light pulse belongs to the extreme ultraviolet range (XUV) of the electromagnetic spectrum, with central photon energy typically between 20 and 200 eV. Related to its brevity, an attosecond pulse has a broad bandwidth covering tens of eV. These