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In this work we investigate the effects of the Gribov prescription to get rid of zero-modes of the Faddeev-Popov operator, at one-loop order in perturbation theory, in the Landau-DeWitt gauge. Quantum fluctuations are taken around a transverse background gauge field. The one-loop effective action is explicitly computed, and the behavior of the gauge and ghost fields propagators are carefully investigated. At one-loop and for generic transverse background configurations the effective action is found to be \textit{not} background invariant, as expected, due to a non-vanishing background contribution. The gauge field propagator has the same form as in the case {where the} background is a trivial field, $i.e.$ with complex conjugate poles, which are modified by the corresponding gap equation. The ghost-anti-ghost propagator still displays its enhanced $\sim p^{-4}$ behavior., Comment: 16 pages, 1 figure

The renormalization properties of two local BRST invariant composite operators, $(O,V_\mu)$, corresponding respectively to the gauge invariant description of the Higgs particle and of the massive gauge vector boson, are scrutinized in the $U(1)$ Higgs model by means of the algebraic renormalization setup. Their renormalization $Z$'s factors are explicitly evaluated at one-loop order in the $\overline{\text{MS}}$ scheme by taking into due account the mixing with other gauge invariant operators. In particular, it turns out that the operator $V_\mu$ mixes with the gauge invariant quantity $\partial_\nu F_{\mu\nu}$, which has the same quantum numbers, giving rise to a $2 \times 2$ mixing matrix. Moreover, two additional powerful Ward identities exist which enable us to determine the whole set of $Z$'s factors entering the $2 \times 2$ mixing matrix as well as the $Z$ factor of the operator $O$ in a purely algebraic way. An explicit check of these Ward identities is provided. The final setup obtained allows for computing perturbatively the full renormalized result for any $n$-point correlation function of the scalar and vector composite operators., Comment: 36 pages, 6 figures

In this paper, we treat the proper path integral quantization of the Yang-Mills-aether (YM-aether) system by dealing with the extra gauge copies in the Landau gauge. Within Gribov's prescription to get rid of such remaining gauge copies, we explicitly derive the Gribov parameter dependence of the coupling constant and of the Lorentz violation aether term. The ultraviolet limit is investigated under the light of recent bounds on the magnitude of the non-Abelian aether parameter, and we show that the Gribov parameter can be disregarded in that limit., Comment: 19 pages, version accepted to Annals of Physics

The content of the present thesis is based on the papers [arXiv:1510.07886 [hep-th]][arXiv:1505.02287 [hep-th]][arXiv:1401.6303 [hep-th]][arXiv:1309.1402 [hep-th]][arXiv:1305.4155 [hep-th]][arXiv:1212.1003 [hep-th]][arXiv:1210.4734 [hep-th]] and is devoted to the study of aspects of the Gribov problem in Euclidean Yang-Mills theories coupled to matter fields. Here, we present some, mathematical and physical, evidences that point to the existence of a possible interplay between the gauge sector and the matter sector, in regimes of sufficiently ow energy (known as the infrared regime). In other words, we claim that an effect in the vector boson sector of Nature due to strong interactions (the Standard Model), at low energies, may be reflected in the matter sector, in the same regime. Specifically, we propose that the Gribov horizon function of the gauge sector may be felt by the matter field, and that it would be described by an effective non-local mass term attached to the matter field. Such a term seems to be dynamically generated and accounts for non-perturbative aspects of the matter field., Comment: Thesis submitted in fulfillment of the requirements for the degree of Doctor of Sciences: Physics at Ghent University, and Doctor in Sciences at Rio de Janeiro State University

In this paper we take into account the existence of Gribov copies in a four-dimensional Yang-Mills theory in the Landau gauge with an effective Lorentz symmetry breaking, induced by the Carroll-Field-Jackiw (CFJ) term. The self consistent gap equation of the Gribov parameter is properly derived and, provided observational bounds to the amplitude of the CFJ parameter in the $SU(2)$ gauge theory, a qualitative analysis of the Gribov parameter and of the poles of the propagator is developed., Comment: 18 pages, version accepted to Journal of Physics A

We employ a set of recent, theoretically motivated, fits to non-perturbative unquenched gluon propagators to check in how far double gluon exchange can be used to describe the soft sector of pp scattering data (total and differential cross section). In particular, we use the refined Gribov--Zwanziger gluon propagator (as arising from dealing with the Gribov gauge fixing ambiguity) and the massive Cornwall-type gluon propagator (as motivated from Dyson-Schwinger equations) in conjunction with a perturbative quark-gluon vertex, next to a model based on the non-perturbative quark-gluon Maris-Tandy vertex, popular from Bethe-Salpeter descriptions of hadronic bound states. We compare the cross sections arising from these models with "older" ISR and more recent TOTEM and ATLAS data. The lower the value of total energy \sqrt{s}, the better the results appear to be., Comment: 14 pages, 8 .pdf figures. To appear in Phys.Rev.C

We present a local setup for the recently introduced BRST-invariant formulation of Yang-Mills theories for linear covariant gauges that takes into account the existence of gauge copies \`a la Gribov and Zwanziger. Through the convenient use of auxiliary fields, including one of the Stueckelberg type, it is shown that both the action and the associated nilpotent BRST operator can be put in local form. Direct consequences of this fully local and BRST-symmetric framework are drawn from its Ward identities: (i) an exact prediction for the longitudinal part of the gluon propagator in linear covariant gauges that is compatible with recent lattice results and (ii) a proof of the gauge-parameter independence of all correlation functions of local BRST-invariant operators., Comment: 29 pages

In this paper, we discuss the gluon propagator in the linear covariant gauges in $D=2,3,4$ Euclidean dimensions. Non-perturbative effects are taken into account via the so-called Refined Gribov-Zwanziger framework. We point out that, as in the Landau and maximal Abelian gauges, for $D=3,4$, the gluon propagator displays a massive (decoupling) behaviour, while for $D=2$, a scaling one emerges. All results are discussed in a setup that respects the Becchi-Rouet-Stora-Tyutin (BRST) symmetry, through a recently introduced non-perturbative BRST transformation. We also propose a minimizing functional that could be used to construct a lattice version of our non-perturbative definition of the linear covariant gauge., Comment: 15 pages, 1 figure; V2 typos fixed and inclusion of section on the ghost propagator. To appear in PhysRev D

We study the ultraviolet properties of theories whose fundamental fields display a confining, Gribov-type, propagator. These are propagators that exhibit complex poles and violate positivity, thus precluding a physical propagating particle interpretation. We show that the properties of this type of confining propagators do not change the ultraviolet behavior of the theory, in the sense that no new ultraviolet primitive divergences are generated, thus securing the renormalizability of these confining theories. We illustrate these properties by studying a variety of models, including bosonic and fermionic confined degrees of freedom. The more intricate case of Super Yang-Mills with ${\cal N} =1$ supersymmetries in the Wess-Zumino gauge is taken as example in order to prove these statements to all orders by means of the algebraic renormalization set up., Comment: 30 pages, 1 figure

This work presents concisely the results obtained from the analysis of the two-point function of the gauge field in the $SU(2)$ and $SU(2)\times U(1)$ gauge theories, in the Landau gauge, coupled to a scalar Higgs field in the fundamental or adjoint representation. Non-perturbative effects are considered by taking into account the Gribov ambiguity. In general, in both Yang-Mills models the gluon propagator has non-trivial contributions of physical and non-physical modes, which clearly depends on the group representation of the Higgs field. These results were presented during the Fourth Winter Workshop on Non-perturbative Quantum Field Theory, which took place in Sophia-Antipolis - France., Comment: 27 pages; review based on the talk given by one of the authors, I. F. Justo, during the Fourth Winter Workshop on Non-perturbative Quantum Field Theory, at Sophia-Antipolis, France, Feb. 2015

We point out the existence of a non-perturbative exact nilpotent BRST symmetry for the Gribov-Zwanziger action in the Landau gauge. We then put forward a manifestly BRST invariant resolution of the Gribov gauge fixing ambiguity in the linear covariant gauge., Comment: 8 pages. v2: version accepted for publication in PhysRevD

We consider finite temperature SU(2) gauge theory in the continuum formulation, which necessitates the choice of a gauge fixing. Choosing the Landau gauge, the existing gauge copies are taken into account by means of the Gribov-Zwanziger (GZ) quantization scheme, which entails the introduction of a dynamical mass scale (Gribov mass) directly influencing the Green functions of the theory. Here, we determine simultaneously the Polyakov loop (vacuum expectation value) and Gribov mass in terms of temperature, by minimizing the vacuum energy w.r.t. the Polyakov loop parameter and solving the Gribov gap equation. Inspired by the Casimir energy-style of computation, we illustrate the usage of Zeta function regularization in finite temperature calculations. Our main result is that the Gribov mass directly feels the deconfinement transition, visible from a cusp occurring at the same temperature where the Polyakov loop becomes nonzero. In this exploratory work we mainly restrict ourselves to the original Gribov-Zwanziger quantization procedure in order to illustrate the approach and the potential direct link between the vacuum structure of the theory (dynamical mass scales) and (de)confinement. We also present a first look at the critical temperature obtained from the Refined Gribov-Zwanziger approach. Finally, a particular problem for the pressure at low temperatures is reported., Comment: 19 pages, 8 .pdf figures. v2: extended section 3 + extra references; version accepted for publication in EPJC

In this note, we consider the Landau gauge in the continuum formulation. Our purposes are twofold. Firstly, we try to work out the consequences of the recently derived Cucchieri-Mendes bounds on the inverse Faddeev-Popov operator at the level of the path integral quantization. Secondly, we give an explicit renormalizable prescription to implement the so-called Landau B-gauges as introduced by Maas., Comment: 17 pages; 2 .pdf figures. v2: version accepted for publication in Eur. Phys. J. C

In light of the development of the Gribov issue for pure Euclidean gauge theories and of the recent lattice measurement of soft breaking of the BRST invariance in Yang-Mills theories in the Landau gauge, we consider non-perturbative features in the gauge-interacting matter sector and their relation with general properties of the Faddeev-Popov operator. A signature for BRST breaking in the matter sector is proposed and a local and renormalizable framework is constructed, accommodating this signature and predicting non-perturbative matter propagators that are consistent with available lattice data for adjoint scalars and quarks., Comment: 25 pages, 3 figures

The issue of the Gribov copies is discussed in Euclidean N=4 Super Yang-Mills theory quantized in the Landau gauge. As a consequence of the absence of a renormalization group invariant scale, it turns out that it is not possible to attach a dynamical meaning to the Gribov parameter. This implies that, in N=4 Super Yang-Mills, there is no need for the restriction of the domain of integration in the functional integral to the Gribov region, and no non-perturbative dynamical scale is generated. This result is in agreement with the absence of a confining phase observed from the Coulomb behaviour of the Wilson loop evaluated through the AdS/CFT correspondence. The non-renormalization theorem of the gluon-ghost-antighost vertex of the Landau gauge is also explicitly checked till three loops., Comment: 10 pages, no figures; v2: discussion on the ghost propagator added, matches version to appear in PLB

The Gribov-Zwanziger framework accounting for the existence of Gribov copies is extended to N=1 Super Yang--Mills theories quantized in the Landau gauge. We show that the restriction of the domain of integration in the Euclidean functional integral to the first Gribov horizon can be implemented in a way to recover non-perturbative features of N=1 Super Yang--Mills theories, namely: the existence of the gluino condensate as well as the vanishing of the vacuum energy., Comment: 19 pages, no figures

The renormalization of N=1 Super Yang-Mills theory is analysed in the Wess-Zumino gauge, employing the Landau condition. An all orders proof of the renormalizability of the theory is given by means of the Algebraic Renormalization procedure. Only three renormalization constants are needed, which can be identified with the coupling constant, gauge field and gluino renormalization. The non-renormalization theorem of the gluon-ghost-antighost vertex in the Landau gauge is shown to remain valid in N=1 Super Yang-Mills. Moreover, due to the non-linear realization of the supersymmetry in the Wess-Zumino gauge, the renormalization factor of the gauge field turns out to be different from that of the gluino. These features are explicitly checked through a three loop calculation., Comment: 15 pages, minor text improvements, references added. Version accepted for publication in the EPJC

It is well accepted that dealing with the Gribov ambiguity has a major impact on correlation functions in gauge-fixed Yang-Mills theories, in particular in the low momentum regime where standard perturbation theory based on the Faddeev-Popov approach fails. Recent results, derived from functional tools (Dyson-Schwinger equations or exact RG) or the effective Gribov-Zwanziger action method, pointed towards e.g. gauge boson correlation functions that are not compatible with the properties of observable degrees of freedom. Although such an observation is a welcome feature for gauge theories exhibiting confinement, it would be a discomfort for gauge theories supplemented with Higgs fields, cfr. the experimental success of the electroweak model based on a SU(2) x U(1) gauge group. The purpose of this short note is to assure that the effective action resolution to the Gribov ambiguity reduces to the standard Faddeev-Popov method in the perturbative regime of sufficiently small coupling/large Higgs condensate, thereby not compromising the physical particle spectrum of massive gauge bosons and a massless photon for the SU(2) x U(1) gauge-Higgs model. The closer the theory gets to the limit of vanishing Higgs condensate, the more the Gribov problem resurfaces with all its consequences. We give some speculations w.r.t. the Fradkin-Shenker insights about the phase diagram., Comment: 10 pages, 2 figures. arXiv admin note: text overlap with arXiv:1305.4155. v2: expanded motivation, extra explanations, extended reference list. Version to appear in Annals of Physics

An all orders algebraic proof of the multiplicative renormalizability of the novel formulation of the Gribov-Zwanziger action proposed in Phys. Rev. D 86, 045005 (2012) [arXiv:1205.3934], and allowing for an exact but spontaneously broken BRST symmetry, is provided., Comment: 15 pages

We study the structure of the gauge propagators of a 3d version of the electroweak interaction in terms of the Higgs vacuum expectation value nu, of the non-Abelian gauge coupling g, and of the Abelian gauge coupling g', when nonperturbative effects related to the non-Abelian gauge fixing are introduced by means of an adapted path integral measure. In the perturbative regime of small non-Abelian coupling g and sufficiently large nu, the well-known standard Z and W propagators are recovered, together with a massless photon. In general, depending on the relative magnitudes of g, g' and nu, we uncover a quite different propagator structure. In a later stage of research, the results here derived can be used to study the associated phase diagram in more depth., Comment: 18 pages, 6 figures

We present an analytical study of continuum 4d SU(2) gauge Higgs models with a single Higgs field with fixed length in either the fundamental or adjoint representation. We aim at analytically probing the renowned predictions of Fradkin & Shenker on the phase diagram in terms of confinement versus Higgs behaviour, obtained for the lattice version of the model. We work in the Landau version of the 't Hooft R_\xi gauges in which case we can access potential nonperturbative physics related to the existence of the Gribov copies. In the fundamental case, we clearly show that in the perturbative regime of small gauge coupling constant g and large Higgs vacuum expectation value v, there is a Higgs phase with Yukawa gauge boson propagators without Gribov effects. For a small value of the Higgs vev v and/or large g, we enter a region with Gribov type propagators that have no physical particle interpretation: the gauge bosons are as such confined. The transition between both behaviours is found to be continuous. In the adjoint case, we find evidence of a more drastic transition between the different behaviours for the propagator of the off-diagonal gauge bosons, whereas the "photon", i.e. the diagonal component of the gauge field, displays a propagator of the Gribov type. In the limit of infinite Higgs condensate, we show that a massless photon is recovered. We compare our findings with those of Fradkin & Shenker as well as with more recent numerical lattice simulations of the fundamental Higgs model. We also carefully discuss in which region of the parameter space (v,g) our approximations are trustworthy., Comment: 21 pages. v2: Extra references, improved discussion, including that of infinite Higgs condensate. Added author

We study SU(2) three-dimensional Yang-Mills theories in presence of Higgs fields in the light of the Gribov phenomenon. By restricting the domain of integration in the functional integral to the first Gribov horizon, we are able to discuss a kind of transition between the Higgs and the confining phase in a semi-classical approximation. Both adjoint and fundamental representation for the Higgs field are considered, leading to a different phase structure., Comment: 12 pages. Version accepted for publication in the EPJC