arXiv subjects

M. Maniatis

Publications and source records attributed to M. Maniatis.

At least 19 recordsLinked to original sources

arXiv2026

Perturbative construction of amplitudes from on-shell trees with vacuum pairs: the all-plus four-gluon amplitude through order $\boldsymbol{g}^{\boldsymbol{6}}$

We formulate a fixed-order perturbative on-shell construction of amplitudes. The basic input is the particle spectrum together with the allowed on-shell three-point amplitudes. The construction is formulated in terms of tree amplitudes generated by BCFW recursion, supplemented by additional unobservable state-conjugate on-shell pairs, called vacuum pairs, and integrated over the Lorentz-invariant phase space of these pairs. The relative signs are assigned as inclusion-exclusion signs for repeated phase-space ranges in the on-shell construction. As a test case, we study the color-ordered four-gluon all-plus amplitude through orders $g^4$ and $g^6$, and compare the resulting signed phase-space sums with the standard one- and two-loop contributions. The fixed-order bookkeeping of the tree amplitudes is organized in terms of polygons. At order $g^4$ the construction reproduces the finite rational one-loop result. At order $g^6$ the non-vanishing polygon sectors are the octagon, hexagon-quadrilateral, two-pentagon, and three-quadrilateral sectors. Taken together, they reproduce the known planar, non-planar, and bow-tie expressions.

hep-th↗

arXiv2025

The Two-Higgs Doublet Model beyond tree-level: A gauge-invariant formalism

Employing the gauge-invariant formalism in the two-Higgs-doublet model (THDM) offers profound insights into the model's fundamental structure. A specific set of gauge-invariant bilinear combinations, constructed from the Higgs doublets, establishes a one-to-one correspondence between the components of the doublet fields and real-valued bilinears. This formalism provides a compact and consistent framework to study various aspects of the THDM, including stability, electroweak symmetry breaking, basis transformations, and general symmetries of the Higgs potential. Recently, the bilinear formalism has been extended beyond the Higgs potential to encompass the full THDM, including the gauge and Yukawa sectors, all in gauge-invariant terms. In this work, we advance the formalism further by incorporating quantum corrections. Specifically, we show how bilinears, combined with the $\hbar$-expansion, can be used to compute one-loop corrections. We provide concise, gauge-invariant expressions for these corrections, which are directly applicable to the THDM.

hep-ph↗

arXiv2024

Electroweak gauge invariant Higgs multiplets

We investigate the potential of general Higgs multiplets. We establish the domain of general Higgs multiplets within the context of the adjoint representation. The construction of the most general potential for arbitrary multiplets is achieved using the irreducible, totally symmetric representation of tensor products of doublets. Furthermore, we explore symmetry transformations of the Higgs multiplets, with particular emphasis on CP symmetries.

hep-ph↗

arXiv2023

CMS results for the $\gamma \gamma$ production at the LHC: do they give a hint for a Higgs boson of the maximally CP symmetric two-Higgs-doublet model?

Recent measurements of the CMS experiment at the LHC show possibly, with about 3 $\sigma$ significance, a resonance in di-photon events with an invariant mass of 95.4 GeV. If this resonance can be confirmed, this could be a hint for a new elementary particle beyond the Standard Model. An additional Standard-model-like Higgs boson with this mass could be excluded by the CMS experiment. We investigate whether this resonance could fit into a two-Higgs-doublet model highly constrained by CP symmetry, the so-called maximally-CP-symmetric model (MCPM). In the strict symmetry limit of the MCPM only the fermions of the third generation obtain masses. We discuss a mechanism where the first and second generation fermions get masses through effects from interactions with very high mass particles. The latter can be integrated out at LHC energies giving effective Lagrangian terms, among them these mass terms. This procedure also gives us a Cabibbo-Kobayashi-Maskawa (CKM) matrix which automatically satisfies some salient structural features observed in experiments. We call the resulting theory MCPM'. Our finding shows that indeed the enhancement measured by CMS could originate from the pseudoscalar Higgs boson $h''$ of this model. According to the model the boson $h''$ would mainly be produced in the Drell-Yan reaction by charm-anticharm-quark fusion. The main decay mode of $h''$ is predicted to be $h'' \to c\bar{c}$. We then consider the so called oblique parameters $S$, $T$, $U$ which give us an allowed region for the mass of the scalar Higgs boson $h'$ versus that of the charged ones $H^\pm$ of the MCPM'. We calculate the effect of these charged bosons $H^\pm$ in the leptonic decays of the charm mesons $D^\pm$ and the charm-strange mesons $D_s^\pm$. Our results indicate that the mass $m_{H^\pm}$ of the charged Higgs bosons $H^\pm$ of the MCPM' should be around 300 GeV.

hep-ph↗

arXiv2021

Fermion mass hierarchy and g-2 anomalies in an extended 3HDM Model

We propose an extension of the three-Higgs-doublet model (3HDM), where the Standard Model (SM) particle content is enlarged by the inclusion of two inert $SU_{2L}$ scalar doublets, three inert and two active electrically neutral gauge singlet scalars, charged vector like fermions and Majorana neutrinos. These additional particles are introduced to generate the SM fermion mass hierarchy from a sequential loop suppression mechanism. In our model the top and exotic fermion masses appear at tree level, whereas the remaining fermions get their masses radiatively. Specifically, bottom, charm, tau and muon masses appear at 1-loop; the masses for the light up, down and strange quarks as well as for the electron at 2-loop and masses for the light active neutrinos at 3-loop. Our model successfully accounts for SM fermion masses and mixings and accommodates the observed Dark Matter relic density, the electron and muon anomalous magnetic moments, as well the constraints arising from charged Lepton Flavor Violating (LFV) processes. The proposed model predicts charged LFV decays within the reach of forthcoming experiments.

hep-ph↗

arXiv2019

Generalised P and CP transformations in the 3-Higgs-doublet model

We study generalised P and CP transformations in the three-Higgs-doublet model (3HDM) with Higgs and gauge fields only. We find that there are two equivalence classes, with respect to flavour transformations, of generalised P transformations and there is only one class of CP transformations. We discuss the conditions the potential has to satisfy in order to be invariant under these transformations. We apply the method of bilinears which we briefly review. We discuss the relation to the conventional basis, where the potential is written in terms of scalar products of the doublet fields. In particular we reproduce the known result that a potential is invariant under CP transformations if and only if there is a conventional basis where all parameters are real. Eventually we study standard P and CP transformations in the $n$-Higgs-doublet model (nHDM). We show that for the bilinears of the nHDM the standard CP transformation corresponds to a diagonal linear transformation with only $\pm 1$ as diagonal elements. We give this matrix explicitly for arbitrary $n$.

hep-ph↗

arXiv2019

The two-real-singlet Dark Matter model

We revisit a Dark Matter model with an extension of the Standard Model with two real singlets $χ$ and $η$ obeying a $Z_2 \otimes Z_2'$ symmetry, where $Z_2'$ is broken spontaneously. While $χ$ serves as a stable Dark Matter candidate providing the relic density, the real $η$ field plays the role of a light mediator. We study the viability of this model with respect to Dark Matter self-interactions which may explain the density profiles observed in dwarf galaxies up to scales of the size of our Milky Way. Moreover, the Standard Model-like Higgs boson of the model has a tiny mixing with the mediator field and appears to be consistent with current LHC data. In this rather minimal extension of the Standard Model the mediator $η$ decays naturally into Majorana neutrinos neither disturbing standard big bang nucleosynthesis nor cosmic microwave background observations.

hep-ph↗

arXiv2019

Application of BCFW-recursion relations and the Feynman-tree theorem to the four gluon amplitude with all plus helicities

Recently it has been shown that in gauge theories amplitudes to any perturbation order can be obtained by glueing together simple three-point on-shell amplitudes. These three-point amplitudes in turn are fixed by locality and Lorentz invariance. This factorization into three-point on-shell amplitudes follows from the BCFW recursion relations and the Feynman-tree theorem. In an explicit example, that is, the four-gluon amplitude with all plus helicities, we illustrate the method. In conventional calculation this amplitude corresponds to one-loop box diagrams.

hep-ph↗

arXiv2017

Illusions - a model of mind

Recognizing that all mental processes have to be unfree and passive, we develop a model of behavior and perceptions. We shall see how misleading our intuition is and shall understand how consciousness arises.

q-bio.NC↗

arXiv2016

The MCPM, a two-Higgs-doublet model with maximal CP symmetry, and LHC13

We continue our investigation of the phenomenological consequences of the MCPM for the LHC experiments. As in any two-Higgs-doublet model we have in the MCPM three neutral Higgs bosons and one charged Higgs-boson pair $H^\pm$. Here we discuss the two-photon production in proton-proton collisions. We find that in the MCPM a resonance-type structure in the $γγ$ invariant mass distribution is predicted around twice the $H^\pm$ mass $m_{H^\pm}$ with a width $2\; Γ_H$ where $Γ_H$ is the $H^\pm$ width. If we set $m_{H^\pm} = 375$ GeV, the above resonance structure appears at 750 GeV with a width of about 45 GeV. We point out various predictions of the MCPM which follow in such a scenario and which can be checked at the LHC.

hep-ph↗

arXiv2016

Scattering amplitudes abandoning virtual particles

We emphasize that scattering amplitudes of a wide class of models to any order in the coupling are constructible by on-shell tree subamplitudes. This follows from the Feynman-tree theorem combined with BCFW on-shell recursion relations. In contrast to the usual Feynman diagrams, no virtual particles appear.

hep-th↗

arXiv2016

Scattering amplitudes from a deconstruction of Feynman diagrams

We show how to apply the BCFW recursion relation to Feynman loop integrals with the help of the Feynman-tree theorem. We deconstruct in this way all Feynman diagrams in terms of on-shell subamplitudes. Every cut originating from the Feynman-tree theorem corresponds to an integration over the phase space of an unobserved particle pair. We argue that we can calculate scattering amplitudes alternatively by the construction of on-shell and gauge-invariant subamplitudes.

hep-th↗

arXiv2015

Stability and symmetry breaking in a three Higgs-boson doublet model with lepton family symmetry O(2)xZ2

Motivated by the neutrino data, an extension of the Standard Model with three Higgs-boson doublets has been proposed. Imposing an O(2) x Z2 family symmetry, a neutrino mixing matrix with theta23 = pi/4 and theta13 = 0 appears in a natural way. Even though these values for the mixing matrix do not follow the recent experimental constraints, they are nevertheless a good approximation. We study the Higgs potential of this model in detail. We apply recent methods which allow for the study of any three-Higgs-boson doublet model. It turns out that for a variety of parameters the potential is stable, has the correct electroweak symmetry breaking, and gives the correct vacuum expectation value.

hep-ph↗

arXiv2015

Stability and symmetry breaking in the general n-Higgs-doublet model

For potentials with n-Higgs-boson doublets stability, electroweak symmetry breaking, and the stationarity equations are discussed in detail. This is done within the bilinear formalism which simplifies the investigation, in particular since irrelevant gauge degrees of freedom are systematically avoided. For the case that the potential leads to the physically relevant electroweak symmetry breaking the mass matrices of the physical Higgs bosons are given explicitly.

hep-ph↗

arXiv2015

Stability and symmetry breaking in the general three-Higgs-doublet model

Stability, electroweak symmetry breaking, and the stationarity equations of the general three-Higgs-doublet model (3HDM) where all doublets carry the same hypercharge are discussed in detail. Employing the bilinear formalism the study of the 3HDM potential turns out to be straightforward. For the case that the potential leads to the physically relevant electroweak symmetry breaking we present explicit formulae for the masses of the physical Higgs bosons.

hep-ph↗

arXiv2012

Towards testing a two-Higgs-doublet model with maximal CP symmetry at the LHC: construction of a Monte Carlo event generator

A Monte Carlo event generator is constructed for a two-Higgs-doublet model with maximal CP symmetry, the MCPM. The model contains five physical Higgs bosons; the $ρ'$, behaving similarly to the standard-model Higgs boson, two extra neutral bosons $h'$ and $h"$, and a charged pair $H^\pm$. The special feature of the MCPM is that, concerning the Yukawa couplings, the bosons $h'$, $h"$ and $H^\pm$ couple directly only to the second generation fermions but with strengths given by the third-generation-fermion masses. Our event generator allows the simulation of the Drell-Yan-type production processes of $h'$, $h"$ and $H^\pm$ in proton-proton collisions at LHC energies. Also the subsequent leptonic decays of these bosons into the $μ^+ μ^-$, $μ^+ ν_μ$ and $μ^- \bar ν_μ$ channels are studied as well as the dominant background processes. We estimate the integrated luminosities needed in $p p$ collisions at center-of-mass energies of 8 TeV and 14 TeV for significant observations of the Higgs bosons $h'$, $h"$ and $H^\pm$ in these muonic channels.

hep-ph↗

arXiv2012

Constraints on the NMSSM from the oblique parameters

Electroweak precision measurements, encoded in the oblique parameters, give strong constraints on physics beyond the Standard Model. The oblique parameters S, T, U (V, W, X) are calculated in the next-to-minimal supersymmetric model (NMSSM). We outline the calculation of the oblique parameters in terms of one-loop gauge-boson selfenergies and find sensitive restrictions for the NMSSM parameter space.

hep-ph↗

arXiv2011

Symmetries and renormalisation in two-Higgs-doublet models

We discuss the classification of symmetries and the corresponding symmetry groups in the two-Higgs-doublet model (THDM). We give an easily useable method how to determine the symmetry class and corresponding symmetry group of a given THDM Higgs potential. One of the symmetry classes corresponds to a Higgs potential with several simultaneous generalised CP symmetries. Extending the CP symmetry of this class to the Yukawa sector in a straightforward way, the so-called maximally-CP-symmetric model (MCPM) is obtained. We study the evolution of the quartic Higgs-potential parameters under a change of renormalisation point. Finally we compute the so called oblique parameters S, T, and U, in the MCPM and we identify large regions of viable parameter space with respect to electroweak precision measurements. We present the corresponding allowed regions for the masses of the physical Higgs bosons. Reasonable ranges for these masses, up to several hundred GeV, are obtained which should make the (extra) Higgs bosons detectable in LHC experiments.

hep-ph↗