International Journal of Modern Physics A

We study a spontaneously broken Einstein–Yang–Mills–Higgs model coupled via a Higgs portal to an uncharged scalar $\chi$. We present a phase diagram of self-gravitating solutions showing that depending on the choice of parameters of the $\chi$ scalar potential and the Higgs portal coupling constant $\gamma$, one can identify different regions: If $\gamma$ is sufficiently small, a $\chi$ halo is created around the monopole core which in turn surrounds a black hole. For larger values of $\gamma$, no halo exists and the solution is just a black hole monopole one. When the horizon radius grows and becomes larger than the monopole radius, solely a black hole solution exists. Because of the presence of the $\chi$ scalar, a bound for the Higgs potential coupling constant exists and when it is not satisfied, the vacuum is unstable and no nontrivial solution exists. We briefly comment on possible connections of our results with those found in recent dark matter axion models.

The holographic complexity of a “black” non-susy D3-brane is computed. The difference in the holographic complexity between this geometry in the Fefferman–Graham coordinates and that of the AdS₅ geometry is obtained for a strip-type subsystem. This is then related to the changes in the energy and the entanglement entropy of the system. We next take the high temperature limit of the change in complexity and observe that it scales with the temperature in the same way as the holographic entanglement entropy. The crossover of the holographic complexity to its corresponding thermal counterpart is similar to the corresponding crossover of the holographic entanglement entropy in the high temperature limit. We further repeat the analysis for ${𝒩}=4$ super-Yang–Mills theory and observe a similar behavior.

General forms of the Kähler and superpotenials that lead to consistent low energy broken Supersymmetry originating from N=1 Supergravity have been classified and used for model building since more than three decades. We point out the incompleteness of this classification when hidden sector vacuum expectation values are of the order of the Planck mass. Focusing in this paper mainly on the case of minimal Kähler potential, we adopt a rigorous approach that retrieves on the one hand the known forms, and demonstrate on the other hand the existence of a whole set of new forms for the superpotential of which we give a complete classification. The latter forms involve a new type of chiral superfields having the unusual property of belonging neither to the hidden sector nor to the conventional observable sector. Comparing the obtained forms with the conventional ones, we argue how new possibilities for model building can arise, and discuss the gravity mediation of soft as well as additional hard (but parametrically small) Supersymmetry breaking, in the presence of the new type of chiral superfields. In the simplest case, we study the vacuum structure, characterize the masses and couplings of the scalar components to the hidden and observable sectors and discuss briefly the physical role they could play. In the generic case, we estimate the magnitude and possible consequences of the hard breaking of Supersymmetry in terms of the interplay between hidden and visible sector mass scales.

We present a systematic analysis of perturbative Hexagonal (HG) mixing for describing recent global fit neutrino mixing data with normal and inverted hierarchy. The corrections to unperturbed mixing are parametrized in terms of small orthogonal rotations $(R)$ with modified PMNS matrix of the forms $\left(\right.R_{\alpha \beta }^l\cdot V_{\text{HG}},V_{\text{HG}}\cdot R_{\alpha \beta }^r,V_{\text{HG}}\cdot R_{\alpha \beta }^r\cdot R_{\gamma \delta }^r,R_{\alpha \beta }^l\cdot R_{\gamma \delta }^l\cdot V_{\text{HG}},R_{\alpha \beta }^l\cdot V_{\text{HG}}\cdot R_{\gamma \delta }^r\left)\right.$. Here, $R_{\alpha \beta }^{l,r}$ is rotation in $ij$ sector and $V_{\text{HG}}$ is unperturbed Hexagonal mixing matrix. The detailed numerical investigation of all possible cases is performed with scanning of parameter space using ${\chi }^2$ approach. We found that the perturbative schemes governed by single rotation are unable to fit the mixing angle data even at $3\sigma$ level. The mixing schemes which involve two rotation matrices only $\left(\right.R_{12}^l\cdot R_{13}^l\cdot V_{\text{HG}},R_{13}^l\cdot R_{12}^l\cdot V_{\text{HG}},R_{13}^l\cdot V_{\text{HG}}\cdot R_{12}^r,R_{12}^l\cdot V_{\text{HG}}\cdot R_{12}^r,R_{13}^l\cdot V_{\text{HG}}\cdot R_{13}^r\left)\right.$ are successful in fitting all neutrino mixing angles within $1\sigma$ range for normal hierarchy (NH). However for inverted hierarchy (IH), only $R_{13}^l\cdot V_{\text{HG}}\cdot R_{13}^r$ is most preferable as it can fit all mixing angles at $1\sigma$ level. The remaining perturbative cases are either excluded at $3\sigma$ level or successful in producing mixing angles only at $2\text{–}3\sigma$ level. To study the impact of phase parameter, we also looked into CP violating effects for single rotation case. The predicted value of ${\delta }_{\mathrm{\text{CP}}}$ lies in the range $39.0^{\circ }(40.4^{\circ })\le \left|{\delta }_{\mathrm{\text{CP}}}\right|\le 78.7^{\circ }(79.2^{\circ })$ for $U_{12}^l\cdot V_{\mathrm{\text{HM}}}$ and $U_{13}^l\cdot V_{\mathrm{\text{HM}}}$ case with normal (inverted) hierarchy.

Super-Poincaré algebra in $D=6$ space–time dimensions has been studied in terms of quaternionic representation of Lorentz group. Starting the connection of quaternion Lorentz group with $SO(1,5)$ group, the $SL(2,ℍ)$ spinors for Dirac and Weyl representations of Poincaré group are described consistently to extend the Poincaré algebra to super-Poincaré algebra for $D=6$ space–time.

The observed hierarchy in the fermion masses, which imply a set of small mass ratios, is not naturally small regarding ’t Hooft’s criteria. In this work, in a model independent approach, we introduce a set of conditions by which fermion mass ratios become natural. Interestingly, these conditions demand that fermion mixing should be described by the four independent mass ratios of each fermion sector. Application of this set of conditions to the standard theory enables one to understand the mains aspects in quark and lepton mixing. This feature can be taken as a strong evidence for the existence in Nature of a flavor symmetry. Also, for this analysis to work in the lepton sector, neutrino masses should have normal ordering with the lightest neutrino mass satisfying the lower bound, $m_{\nu 1}\ge (5.0\pm 0.1)\text{MeV}$, making the approach testable.