arXiv subjects

Thierry Grandou

Publications and source records attributed to Thierry Grandou.

17 recordsLinked to original sources

arXiv2024

Neither a field nor a matter: The case of energy

Energy is no doubt an intuitive concept. Following a previous analysis on the nature of elementary particles and associated elementary quantum fields, the peculiar status and role of energy is scrutinised further at elementary and larger scales. Energy physical characterisation shows that it is a primordial component of reality highlighting the quantum fields natural tendencies to interact, the elementary particles natural tendency to constitute complex bodies and every material thing natural tendency to actualise and be active. Energy therefore is a primordial notion in need of a proper assessment.

physics.gen-ph↗

arXiv2024

On the Yang-Mills propagator at strong coupling

About twelve years ago the use of standard functional manipulations was demonstrated to imply an unexpected property satisfied by the fermionic Green's functions of QCD. This non-perturbative phenomenon is dubbed Effective Locality. In a much simpler way than in QCD, the most remarkable and intriguing aspects of Effective Locality have been presented in a recent letter in the Yang-Mills theory on Minkowski spacetime. While quickly recalled in the current paper, these results are used to calculate the problematic gluonic propagator in the Yang-Mills non-perturbative regime.

hep-th↗

arXiv2022

On emergent particles and stable neutral plasma balls in SU(2) Yang-Mills thermodynamics

For a pure SU(2) Yang-Mills theory in 4D we revisit the spatial (3D), ball-like region of radius $r_0$, in its bulk subject to the pressureless, deconfining phase at $T_0=1.32\,T_c$ where $T_c$ denotes the critical temperature for the onset of the deconfining-preconfining phase transition. Such a region possesses of a finite energy density and represents the self-intersection of a figure-eight shaped center-vortex loop if a BPS monopole of core radius $\sim \frac{r_0}{52.4}$, isolated from its antimonopole by repulsion externally invoked through a transient shift of (anti)caloron holonomy (pair creation), is trapped therein. The entire soliton (vortex line plus region of self-intersection of mass $m_0$ containing the monopole) can be considered an excitation of the pressureless and energyless ground state of the confining phase. Correcting an earlier estimate of $r_0$, we show that the vortex-loop self-intersection region associates with the {\sl central part} of a(n) (anti)caloron and that this region carries one unit of electric U(1) charge via the (electric-magnetic dually interpreted) charge of the monopole. The monopole core quantum vibrates at a thermodynamically determined frequency $ω_0$ and is unresolved. For a deconfining-phase plasma oscillation about the zero-pressure background at $T=T_0$ we compute the lowest frequency $Ω_0$ within a {\sl neutral} and homogeneous spatial ball (no trapped monopole) in dependence of its radius $R_0$. For $R_0=r_0$ a comparison of $Ω_0$ with $ω_0$ reveals that the neutral plasma oscillates much slower than the same plasma driven by the oscillation of a monopole core.

hep-th↗

arXiv2021

QCD Effective Locality : A Theoretical and Phenomenological Review

About ten years ago the use of standard functional manipulations was demonstrated to imply an unexpected property satisfied by the fermionic Green's functions of QCD and dubbed Effective Locality. This feature of QCD is nonperturbative as it results from a full gauge invariant integration of the gluonic degrees of freedom. In this review article, a few salient theoretical aspects and phenomenological applications of this property are summarized.

hep-th↗

arXiv2020

On the absence of the Gribov copy problem in `effective locality' QCD calculations

About ten years ago the use of standard functional manipulations was demonstrated to imply an unexpected property satisfied by the fermionic Green's functions of QCD and dubbed effective locality. This feature of QCD is non-perturbative as it results from a full gauge invariant summation of the gluonic degrees of freedom. This astounding result has lead to suspect that in a way or other, the famous Gribov copy problem had been somewhat overlooked. It is argued that it is not so.

hep-th↗

arXiv2019

Effective locality and chiral symmetry breaking in QCD

A few years ago the use of standard functional manipulations was demonstrated to imply an unexpected property satisfied by the fermionic Green's functions of QCD, and called effective locality. This feature of QCD is non-perturbative as it results from a full integration of the gluonic degrees of freedom. In this paper, at eikonal and quenching approximation at least, the relation of effective locality to dynamical chiral symmetry breaking is examined.

hep-th↗

arXiv2019

On Quantum Fields at High Temperature

Revisiting the fast fermion damping rate calculation in a thermalized QED and/or QCD plasma at 4-loop order, focus is put on a peculiar perturbative structure which has no equivalent at zero-temperature. Not surprisingly and in agreement with previous $C^\star$-algebraic analyses, this structure renders the use of thermal perturbation theory quite questionable.

hep-th↗

arXiv2018

Chiral Symmetry Breaking out of QCD Effective Locality

The QCD non-perturbative property of Effective Locality whose essential meaning has been disclosed recently, is here questioned about the chiral symmetry breaking phenomenon, one of the two major issues of the non-perturbative phase of QCD. As a first attempt, quenching and the eikonal approximation are used so as to simplify calculations which are quite involved. Chiral symmetry breaking appears to be realised in close connection to the Effective Locality mass scale, $μ^2$ , as could be expected.

hep-th↗

arXiv2017

On the non-perturbative realization of QCD gauge-invariance

A few years ago the use of standard functional manipulations was demonstrated to imply an unexpected property satisfied by the fermionic Green's functions of QCD: effective locality. This feature of QCD is non-perturbative as it results from a full integration of the gluonic degrees of freedom. In this paper, previous derivations of effective locality are reviewed, corrected, and enhanced. Focussing on the way non-abelian gauge invariance is realized in the non-perturbative regime of QCD, the deeper meaning of effective locality is discussed.

hep-th↗

arXiv2017

Comparison of Gluon Bundle based QCD Curves with ISR Elastic pp Scattering Data

Using previously described functional techniques for exact, non-perturbative, gauge-invariant renormalized QCD processes, a simplified version of the amplitudes - in which forms akin to Pomerons naturally appear - provides fits to ISR Elastic pp scattering data. Extension of this work to LHC reactions is presently underway.

hep-ph↗

arXiv2017

Massive loops in thermal SU(2) Yang-Mills theory: Radiative corrections to the pressure beyond two loops

We device an efficient book-keeping of excluded energy-sign and scattering-channel combinations for the loop four-momenta associated with massive quasi-particles, circulating in (connected) bubble diagrams subject to vertex constraints inherited from the thermal ground state. The according radiative corrections modify the free thermal-quasiparticle pressure at one loop. Increasing the loop order in two-particle irreducible (2PI) bubble diagrams, we exemplarily demonstrate a suppressing effect of the vertex constraints on the number of valid combinations. This increasingly strong suppression gave rise to the conjecture in hep-th/0609033 that the loop expansion would terminate at a finite order. Albeit the low-temperature dependence of the 2PI 3-loop diagram complies with this behaviour, a thorough analysis of the high-temperature situation reveals that the leading power in temperature is thirteen such that this diagram dominates all lower loop orders for sufficiently high temperatures. An all-loop-order resummation of 2PI diagrams with dihedral symmetry is thus required, defining an extremely well-bounded analytical continuation of the low-temperatures result.

hep-th↗

arXiv2015

Thermal ground state and nonthermal probes

The Euclidean formulation of SU(2) Yang-Mills thermodynamics admits periodic, (anti)selfdual solutions to the fundamental, classical equation of motion which possess one unit of topological charge: (anti)calorons. A spatial coarse graining over the central region in a pair of such localised field configurations with trivial holonomy generates an inert adjoint scalar field $ϕ$, effectively describing the pure quantum part of the thermal ground state in the induced quantum field theory. Here we show for the limit of zero holonomy how (anti)calorons associate a temperature independent electric permittivity and magnetic permeability to the thermal ground state of SU(2)$_{\tiny\mbox{CMB}}$, the Yang-Mills theory conjectured to underlie photon propagation.

hep-th↗

arXiv2004

Spacetime deployments parametrized by gravitational and electromagnetic fields

On the basis of a "Punctual" Equivalence Principle of the general relativity context, we consider spacetimes with measurements of conformally invariant physical properties. Then, applying the Pfaff theory for PDE to a particular conformally equivariant system of differential equations, we make explicit the dependence of any kind of function describing a "spacetime deployment", on n(n+1) parametrizing functions, denoting by n the spacetime dimension. These functions, appearing in a linear differential Spencer sequence and determining gauge fields of spacetime deformations relatively to a "substrat spacetime", can be consistently ascribed to unified electromagnetic and gravitational fields, at any spacetime dimensions n greater or equal to 4.

hep-th↗

arXiv2004

Time 'betwins'

Discussions on the Langevin Twins 'paradox' are most often based on a "triangular" diagram which outlines the twins spacetime travels. It won't be our way, avoiding what we think to be a problem at the basis of numerous controversies. Our approach relies on a fundamentally different Equivalence Principle, namely the so-called "Punctual Equivalence Principle", from which we think that a very conformal aspect proceeds. We present a resolution of this paradox in the framework of the so-called "scale gravity". This resolution hinges on a clear determinism of the Twins proper times, in some definite situations, and a fundamental under-determinism in some other particular ones, the physical discrimination of which being achieved out of a precise mathematical description of conformal geometry. Moreover, we find that the time discrepancy between the twins, could somehow be at the root expression of the second fundamental law of thermodynamics.

gr-qc↗

arXiv2003

Angular intricacies in hot gauge field theories

It is argued that in hot gauge field theories, "Hard Thermal Loops" leading order calculations call for a definite sequence of angular averages and discontinuity (or Imaginary part prescription) operations, and run otherwise into incorrect results. The ten years old collinear singularity problem of hot $QCD$, provides a striking illustration of that fate.

hep-ph↗

arXiv2003

Proof of a mass singularity free property in high temperature QCD

It is shown that three series of diagrams entering the calculation of some hot $QCD$ process, are mass (or collinear) singularity free, indeed. This generalizes a result which was recently established up to the third non trivial order of (thermal) Perturbation Theory.

hep-th↗

arXiv1996

On the Light Cone Singularity of the Thermal Effective Expansion

We consider a scalar massless quantum field model, at finite temperature $T$, both renormalizable and asymptotically free. Focussing on the singular structure of the effective perturbation theory about the light cone, several new insights are put forth, regarding the interplay between hard thermal loop resummation and the overall compensation of collinear singularities.

hep-ph↗