Search results for "Parameter space"
showing 10 items of 182 documents
Topological protection of highly entangled non-Gaussian two-photon states
2021
Abstract We study theoretically the evolution of entangled non-Gaussian two-photon states in disordered topological lattices. Specifically, we consider spatially entangled two-photon states, modulated by Laguerre polynomials up to the 3rd order, which feature ring-shaped spatial and spectral correlation patterns. Such states are discrete analogs of photon-subtracted squeezed states, which are ubiquitous in optical quantum information processing or sensing applications. We find that, in general, a higher degree of entanglement coincides with a loss of topological protection against disorder, this is in line with previous results for Gaussian two-photon states. However, we identify a particul…
Closed Busse balloon for rolls and skew-varicose instability in a Swift-Hohenberg model with nonlinear resonance
1998
Abstract A Swift-Hohenberg model incorporating a nonlinear resonance is shown to produce stable rolls only in a closed region of the parameter space. This Busse balloon is limited by zigzag and Eckhaus boundaries. A skew-varicose instability outside the balloon also exists. Implications with nonlinear optics and hydrodynamic convection are commented.
Distributed learning automata-based scheme for classification using novel pursuit scheme
2020
Learning Automata (LA) is a popular decision making mechanism to “determine the optimal action out of a set of allowable actions” (Agache and Oommen, IEEE Trans Syst Man Cybern-Part B Cybern 2002(6): 738–749, 2002). The distinguishing characteristic of automata-based learning is that the search for the optimising parameter vector is conducted in the space of probability distributions defined over the parameter space, rather than in the parameter space itself (Thathachar and Sastry, IEEE Trans Syst Man Cybern-Part B Cybern 32(6): 711–722, 2002). Recently, Goodwin and Yazidi pioneered the use of Ant Colony Optimisation (ACO) for solving classification problems (Goodwin and Yazidi 2016). In th…
The 0-Parameter Case
1998
As an introduction to the theory of bifurcations, in this chapter we want to consider individual vector fields, i.e., families of vector fields with a 0-dimensional parameter space. We will present two fundamentals tools: the desingularization and the asymptotic expansion of the return map along a limit periodic set. In the particular case of an individual vector field these techniques give the desired final result: the desingularization theorem says that any algebraically isolated singular point may be reduced to a finite number of elementary singularities by a finite sequence of blow-ups. If X is an analytic vector field on S 2, then the return map of any elementary graphic has an isolate…
Explaining 750 GeV diphoton excess from top/bottom partner cascade decay in two-Higgs-doublet model extension
2016
In this paper, we interpret the 750 GeV diphoton excess in the Zee-Babu extension of the two-Higgs-doublet model by introducing a top partner ($T$)/bottom partner ($B$). In the alignment limit, the 750 GeV resonance is identified as the heavy CP-even Higgs boson ($H$), which can be sizably produced via the QCD process $pp \to T\bar{T}$ or $pp \to B\bar{B}$ followed by the decay $T\to Ht$ or $B \to Hb$. The diphoton decay rate of $H$ is greatly enhanced by the charged singlet scalars predicted in the Zee-Babu extension and the total width of $H$ can be as large as 7 GeV. Under the current LHC constraints, we scan the parameter space and find that such an extension can account for the observe…
Anisotropic quark stars with an interacting quark equation of state
2019
A deep exploration of the parameter space that relates the interacting equation of state with the bag constant B, and the interaction parameter a, is fundamental for the construction of diverse models of quark stars. In particular, the anisotropy of quark stars with a well-motivated quantum chromodynamics (QCD) equation of state is presented here. The contribution of the fourth order corrections parameter ($\mathrm{a}$) of the QCD perturbation on the radial and tangential pressure generate significant effects on the mass-radius relation and the stability of the quark star. An adequate set of solutions for several values of the bag factor and the interaction parameter are used in order to ca…
Direct search for charged Higgs bosons in decays of top quarks
2001
We present a search for charged Higgs bosons in decays of pair-produced top quarks in pbar p collisions at sqrt(s) = 1.8 TeV using 62.2 pb^-1 of data recorded by the D0 detector at the Fermilab Tevatron collider. No evidence is found for signal, and we exclude at 95% confidence most regions of the (M higgs, tan beta) parameter space where the decay t->H b has a branching fraction greater than 0.36 and B(H -> tau nu) is large.
Anatomy of flavour-changing Z couplings in models with partial compositeness
2013
In models with partially composite quarks, the couplings of quarks to the Z boson generically receive non-universal corrections that are not only constrained by electroweak precision tests but also lead to flavour-changing neutral currents at tree level. The impact of these flavour-changing couplings on rare K and B decays is studied in two-site models for three scenarios: an anarchic strong sector with two different choices of fermion representations both leading to a custodial protection of the Z->bb coupling, and for a strong sector invariant under a U(2)^3 flavour symmetry. In the complete numerical analysis, all relevant constraints from Delta(F)=2 processes are taken into account. …
Anticipating the higher generations of quarks from rephasing invariance of the mixing matrix
1986
Abstract We show that the number of invariant CP violating parameters X CP jumps from the unique universal one in three generations to nine in the four-generation case, saturating the parameter space for generation numbers higher than three. This can lead to drastically different consequences in CP -violating phenomena. We give the quark mass matrices in the three-generation case and speculate for higher generations. We also give some invariant definitions of “maximal” CP violation.
LHC diphoton resonance from gauge symmetry
2015
Motivated by what is possibly the first sign of new physics seen at the LHC, the diphoton excess at $750$ GeV in ATLAS and CMS, we present a model that provides naturally the necessary ingredients to explain the resonance. The simplest phenomenological explanation for the diphoton excess requires a new scalar state, $X(750)$, as well as additional vector-like (VL) fermions introduced in an ad-hoc way in order to enhance its decays into a pair of photons and/or increase its production cross-section. We show that the requiered VL quarks and their couplings can emerge naturally from a complete framework based on the $SU(3)_L \otimes U(1)_\mathcal{X}$ gauge symmetry.