Search results for "Doublet"
showing 10 items of 40 documents
Transient FTIR spectroscopy after one- and two-colour excitation on a highly luminescent chromium(III) complex.
2021
The development of photoactive transition metal complexes with Earth-abundant metals is a rapidly growing research field, where a deeper understanding of the underlying photophysical processes is of great importance. A multitude of potential applications in the fields of photosensitizing, optical sensing, photoluminescence and photoredox catalysis motivates demanding spectroscopic studies. We applied a series of high-level spectroscopic methods on the previously reported highly luminescent chromium(iii) complex [Cr(ddpd)2](BF4)3 (ddpd = N,N'-dimethyl-N,N'-dipyridine-2-ylpyridine-2,6-diamine) possessing two near-IR emissive doublet states with microsecond lifetimes. Luminescence measurements…
$\texttt{HEPfit}$: a Code for the Combination of Indirect and Direct Constraints on High Energy Physics Models
2020
The European physical journal / C Particles and fields C80(5), 456 (2020). doi:10.1140/epjc/s10052-020-7904-z
Yukawa Alignment in the Two-Higgs-Doublet Model
2009
5 páginas, 1 tabla.-- PACS numbers: 12.60.Fr, 11.30.Hv, 12.15.Mm, 14.80.Cp
An extension of two-Higgs-doublet model and the excesses of 750 GeV diphoton, muon g-2 and h → μτ
2016
In this paper we simultaneously explain the excesses of the 750 GeV diphoton, muon g-2 and $h\to \mu\tau$ in an extension of the two-Higgs-doublet model (2HDM) with additional vector-like fermions and a CP-odd scalar singlet ($P$) which is identified as the 750 GeV resonance. This 750 GeV resonance has a mixing with the CP-odd scalar ($A$) in 2HDM, which leads to a coupling between $P$ and the SM particles as well as a coupling between $A$ and the vector-like fermions. Such a mixing and couplings are strongly constrained by $\tau\to\mu\gamma$, muon g-2 and the 750 GeV diphoton data. We scan over the parameter space and find that such an extension can simultaneously account for the observed …
Vacuum Topology of the Two Higgs Doublet Model
2011
We perform a systematic study of generic accidental Higgs-family and CP symmetries that could occur in the two-Higgs-doublet-model potential, based on a Majorana scalar-field formalism which realizes a subgroup of GL(8,C). We derive the general conditions of convexity and stability of the scalar potential and present analytical solutions for two non-zero neutral vacuum expectation values of the Higgs doublets for a typical set of six symmetries, in terms of the gauge-invariant parameters of the theory. By means of a homotopy-group analysis, we identify the topological defects associated with the spontaneous symmetry breaking of each symmetry, as well as the massless Goldstone bosons emergin…
Radiative Corrections to Scalar Masses and Mixing in a Scale Invariant Two Higgs Doublet Model
2012
We study the Higgs-boson mass spectrum of a classical scale-invariant realization of the two-Higgs-doublet model (SI-2HDM). The classical scale symmetry of the theory is explicitly broken by quantum loop effects due to gauge interactions, Higgs self-couplings and top-quark Yukawa couplings. We determine the allowed parameter space compatible with perturbative unitarity and electroweak precision data. Taking into account the LEP and the recent LHC exclusion limits on a Standard-Model-like Higgs boson H_SM, we obtain rather strict constraints on the mass spectrum of the heavy Higgs sector of the SI-2HDM. In particular, if M_{H_SM} \sim 125 GeV, the SI-2HDM strongly favours scenarios, in which…
Elimination of unitarily nonequivalent vacua in supersymmetric grand unified theories by gravity
1983
Abstract In globally supersymmetric grand unified theories, there may be unitarily nonequivalent vacua which are not present in ordinary theories, reflecting the invariance of the Higgs potential under the complex extension of the gauge group. We show that such vacua are eliminated in the presence of N = 1 supergravity coupling, if local supersymmetry is broken and the costomological constant vanishes.
Higgs pair signal enhanced in the 2HDM with two degenerate 125 GeV Higgs bosons
2015
We discuss a scenario of the type-II 2HDM in which the $b\bar{b}\gamma\gamma$ rate of the Higgs pair production is enhanced due to the two nearly degenerate 125 GeV Higgs bosons ($h$, $H$). Considering various theoretical and experimental constraints, we figure out the allowed ranges of the trilinear couplings of these two Higgs bosons and calculate the signal rate of $b\bar{b}\gamma\gamma$ from the productions of Higgs pairs ($hh$, $hH$, $HH$) at the LHC. We find that in the allowed parameter space some trilinear Higgs couplings can be larger than the SM value by an order and the production rate of $b\bar{b}\gamma\gamma$ can be greatly enhanced. We also consider a "decoupling" benchmark po…
Flavour-changing top decays in the aligned two-Higgs-doublet model
2015
We perform a complete one-loop computation of the two-body flavour-changing top decays $t \rightarrow c h$ and $t \rightarrow c V$ ($V= \gamma, Z$), within the aligned two-Higgs-doublet model. We evaluate the impact of the model parameters on the associated branching ratios, taking into account constraints from flavour data and measurements of the Higgs properties. Assuming that the $125$~GeV Higgs corresponds to the lightest CP-even scalar of the CP-conserving aligned two-Higgs-doublet model, we find that the rates for such flavour-changing top decays lie below the expected sensitivity of the future high-luminosity phase of the LHC. Measurements of the Higgs signal strength in the di-photo…
Light charged Higgs at the beginning of the LHC era
2008
The terascale will be explored with the start of the LHC. One of the most fundamental questions which we expect to be answered is the root of electroweak symmetry breaking and whether the Higgs mechanism is realized in nature or not. In this context we pose the question if existing experimental data still allow for a light non-minimal Higgs sector. We tackle this question first in the context of the two Higgs doublet model and then we concentrate in two supersymmetric models, the constrained MSSM and the MSSM with non-universal Higgs masses. In both supersymmetric scearios, light pseudoscalar and light charged-Higgs bosons are still viable provided tan beta is large. In this regime, we emph…