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A. R. Fazio

Publications and source records attributed to A. R. Fazio.

At least 19 recordsLinked to original sources
arXiv2023

Higgs Boson Mass Corrections at Three-Loops in the Top-Yukawa Sector of the Standard Model

The search for new physics signals in Higgs precision measurements plays a pivotal role in the High-Luminosity Large Hadron Collider (HL-LHC) and future colliders programs. The Higgs properties are expected to be measured with great experimental precision, implying higher-order perturbative computations of the electroweak parameters from the theoretical side. In particular, the renormalized Higgs boson mass parameter in the Standard Model shows significant variation around the electroweak scale, resulting in a lower-bound theoretical uncertainty that exceeds future collider expectations. A more stable result under the renormalization group can be computed from a non-zero external momentum Higgs self-energy, for which available calculations include 3-loop corrections in the QCD sector. In this work, we present an additional contribution by estimating the leading non-QCD 3-loop corrections to the mass of the Higgs boson in the top-Yukawa sector of order $y_t^6$. The momentum-dependent Higgs self-energy is computed in the tadpole-free scheme for the Higgs vacuum expectation value in the Landau gauge, and the explicit dependence upon the Higgs boson and top quark masses is shown. The obtained result is expressed in dimensional regularization as a superposition of a set of master integrals with coefficients that are free of poles in four space-time dimensions, and the corrections are evaluated numerically by the sector decomposition method.

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arXiv2022

High Precision Calculations of the Higgs Boson Mass

In this paper we are going to review the status of the computations of the perturbative quantum corrections to the Higgs boson mass in the Standard Model and in its supersymmetric extensions. In particular, supersymmetric theories require a very accurate computation of the Higgs boson mass, which includes corrections up to even three-loop level, since their predictions are limited by theoretical uncertainties. A discussion about these uncertainties in the context of the minimal and next to minimal supersymmetric standard models is included.

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arXiv2021

A functional approach to the next to eikonal approximation of high energy gravitational scattering

The Fradkin-Schwinger functional methods to represent a Green function in an external gravitational field are used to study the eikonal and the next-to-eikonal limit, including the nonlinear gravitational interactions, of the scattering amplitudes of an ultra-relativistic scalar particle on a static super-massive scalar target in the nearly forward limit. The functional approach confirms the exponentiation of the leading eikonal which also applies to the first non-leading power in the energy of the light particle, moreover includes the interaction at impact parameter much larger than the Schwarzschild radius associated with the center of mass energy in the ultra-relativistic limit.

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arXiv2019

Cosmological Correlators, In-In Formalism and Double Copy

We are investigating if the double copy structure as product of scattering amplitudes of gauge theories applies to cosmological correlators computed in a class of theories for inflation by the operatorial version of the In-In formalism of Schwinger-Keldysh. We consider tree level momentum-space correlators involving primordial gravitational waves with different polarizations and the scalar curvature fluctuations on a three dimensional fixed spatial slice. The correlators are sum of terms factorized in a time dependent scalar factor, which takes into account the curved background where energy is not conserved, and in a so-called tensor factor, constructed by polarization tensors. In the latter we recognize scattering amplitudes in four dimensional Minkowski space spanned by three points gravitational amplitudes related by double copy to those of gauge theories. Our study indicates that gravitational waves are double copy of gluons and the primordial scalar curvature is double copy of a scalar with Higgs-like interactions.

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arXiv2019

Comparison of the EFT Hybrid and Three-Loop Fixed-Order Calculations of the Lightest MSSM Higgs Boson Mass

The lightest Higgs boson mass of the Minimal Supersymmetric Standard Model has been recently computed diagrammatically at the three-loop order in the whole supersymmetric parameters space of the SUSY-QCD sector. The code FeynHiggs combines one- and two-loop fixed-order with the effective-field-theory calculations for the same Higgs mass. The two numerical predictions agree considering the scenario of only one SUSY-scale and vanishing stop mixing parameter below 10 TeV. The agreement is improved by introducing an additional supersymmetric scale and a non-zero stop mixing. Additionally, the combined CMS/ATLAS Higgs mass value was used to derive an upper bound on the needed SUSY scale. In the considered scenario, values above the scale $12.5\pm1.2~\rm{TeV}$ are excluded.

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arXiv2019

The Lightest Higgs Boson Mass of the MSSM at Three-Loop Accuracy

In this article we provide explicit computations of the quantum corrections to the lightest CP-even Higgs Boson mass in the real version of the Minimal Supersymmetric Standard Model. We compute the contributions coming from the SUSY-QCD sector with a precision of three loops at order $O(α_tα_s^2)$. The renormalization procedure adopted is based on the dimensional reduction scheme in order to preserve supersymmetry to all perturbative orders. The calculation extends the region of validity of previous studies to the whole supersymmetric parameter space. The involved master integrals have been computed by exploiting new proposed approaches based on the dispersion relation techniques for the numerical calculation of three-loop vacuum integrals with arbitrary mass scales.

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arXiv2015

Generalised Unitarity for Dimensionally Regulated Amplitudes

We present a novel set of Feynman rules and generalised unitarity cut-conditions for computing one-loop amplitudes via d-dimensional integrand reduction algorithm. Our algorithm is suited for analytic as well as numerical result, because all ingredients turn out to have a four-dimensional representation. We will apply this formalism to NLO QCD corrections.

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arXiv2012

Helicity Spinor Methods and Tree Level QCD Corrections in Higgs Production via Weak Boson Fusion

We calculate analytically tree level amplitudes for Higgs production via Weak Bosons Fusion (WBF) and QCD corrections to the Standard Model prediction (SM) by using the helicity spinor formalism. We provide the explicit expression for the amplitude with two gluons emission in the final state together with massless final two quarks. The massive generalization of the Britto-Cachazo-Feng-Witten (BCFW) recursion scheme is applied successfully obtaining compact results which agree with, and overcome in simplicity, the conventional Feynman diagrams approach.

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arXiv2011

Comments on Anomaly Cancellations by Pole Subtractions and Ghost Instabilities with Gravity

We investigate some aspects of anomaly cancellation realized by the subtraction of an anomaly pole, stressing on some of its properties in superspace. In a local formulation these subtractions can be described in terms of a physical scalar, an axion and related ghosts. They appear to be necessary for the unitarization of the theory in the ultraviolet, but they may generate an infrared instability of the corresponding effective action, signalled by ghost condensation. In particular the subtraction of the superanomaly multiplet by a pole in superspace is of dubious significance, due to the different nature of the chiral and conformal anomalies. In turn, this may set more stringent constraints on the coupling of supersymmetric theories to gravity.

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arXiv2010

The pomeron in closed bosonic string theory

We review the features of the pomeron in the S-matrix theory and in quantum field theory. We extend those general properties to the pomeron of closed bosonic string theory in a Minkowskian background. We compute the couplings of the pomeron to the lowest mass levels of closed bosonic string states in flat space. We recognize the deviation from the linearity of the Regge trajectories in a five dimensional anti De Sitter background.

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arXiv2005

Massless Three Dimensional Quantum Electrodynamics and Thirring Model Constrained by Large Flavor Number

We explicitly prove that in three dimensional massless quantum electrodynamics at finite temperature, zero density and large number of flavors the number of infrared degrees of freedom is never larger than the corresponding number of ultraviolet. Such a result, strongly dependent on the asymptotic freedom of the theory, is reversed in three dimensional Thirring model due to the positive derivative of its running coupling constant.

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arXiv2005

Wilson Coefficient For Vacuum Condensate Of Photons From Electrodynamics Photon Propagator

In the framework of the operator product expansion I provide a detailed evaluation of the contribution of the lowest photon condensate to the two-point photon Green function for four-dimensional spinor electrodynamics and three-dimensional scalar electrodynamics. Since the above mentioned condensate affects the part of the propagator contributing to physical amplitudes I suggest that this condensate could play a role in the non-perturbative dynamics of Abelian gauge field theories.

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arXiv2004

Two-loop ghost-antighost condensation for SU(2) Yang-Mills theories in the Maximal Abelian Gauge

In the framework of the formalism of Cornwall et all. for composite operators I study the ghost-antighost condensation in SU(2) Yang-Mills theories quantized in the Maximal Abelian Gauge and I derive analytically a condensating effective potential at two ghost loops. I find that in this approximation the one loop pairing ghost-antighost is not destroyed but no mass is generated if the ansatz for the propagator suggested by the tree level Hubbard-Stratonovich transformations is used.

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arXiv2003

Two-loop world-sheet effective action

We are studying quantum corrections in the earlier proposed string theory based on world-sheet action which measures the linear sizes of the surfaces. At classical level the string tension is equal to zero and as it was demonstrated in the previous studies one loop correction to the classical world-sheet action generates Nambu-Goto area term, that is nonzero string tension. We extend this analysis computing the world-sheet effective action in the second order of the loop expansion.

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