arXiv subjects

M. S. Guimaraes

Publications and source records attributed to M. S. Guimaraes.

83 records · Page 5Linked to original sources

arXiv2010

Dual approaches for defects condensation

We review two methods used to approach the condensation of defects phenomenon. Analyzing in details their structure, we show that in the limit where the defects proliferate until occupy the whole space these two methods are dual equivalent prescriptions to obtain an effective theory for the phase where the defects (like monopoles or vortices) are completely condensed, starting from the fundamental theory defined in the normal phase where the defects are diluted.

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arXiv2010

Study of the properties of the Gribov region in SU(N) Euclidean Yang-Mills theories in the maximal Abelian gauge

In this paper we address the issue of the Gribov copies in SU(N), N>2, Euclidean Yang-Mills theories quantized in the maximal Abelian gauge. A few properties of the Gribov region in this gauge are established. Similarly to the case of SU(2), the Gribov region turns out to be convex, bounded along the off-diagonals directions in field space, and unbounded along the diagonal ones. The implementation of the restriction to the Gribov region in the functional integral is discussed through the introduction of the horizon function, whose construction will be outlined in detail. The influence of this restriction on the behavior of the gluon and ghost propagators of the theory is also investigated together with a set of dimension two condensates.

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arXiv2010

Gribov horizon and BRST symmetry: a pathway to confinement

We summarize the construction of the Gribov-Zwanziger action and how it leads to a scenario which explains the confinement of gluons, in the sense that the elementary gluon excitations violate positivity. Then we address the question of how one can construct operators within this picture whose one-loop correlation functions have the correct analytic properties in order to correspond to physical excitations. For this we introduce the concept of i-particles.

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arXiv2009

Equivalence between Zwanziger's horizon function and Gribov's no-pole ghost form factor

The ghost form factor entering the Gribov no-pole condition is evaluated till the third order in the gauge fields. The resulting expression turns out to coincide with Zwanziger's horizon function implementing the restriction to the Gribov region in the functional integral.

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arXiv2009

Lorentz-violating Chern-Simons action under high temperature in massless QED

Lorentz and CPT violating QED with massless fermions at finite temperature is studied. We show that there is no ambiguity in the induced coefficient of the Chern-Simons-like term that defines the so-called Carroll-Field-Jackiw model at high temperature. We also show that this system constitutes an example where the breaking of CPT and Lorentz symmetries is more severe at high temperature than in the zero temperature case thus precluding any naive expectations of Lorentz symmetry restoration.

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arXiv2009

Monopoles in the presence of the Chern-Simons term via the Julia-Toulouse approach

We study $QED_3$ with magnetic-like defects using the Julia-Toulouse condensation mechanism (JTM). By a careful treatment of the symmetries we suggest a geometrical interpretation for distinct debatable issues in the MCS-monopole system: (i) the induction of the non-conserved electric current together with the Chern-Simons term (CS), (ii) the deconfinement transition and, (iii) the computation of the fermionic determinant in the presence of Dirac string singularities. The JTM leads to proper interpretation of the non-conserved current as originating from Dirac brane symmetry breaking. The mechanism behind this symmetry breaking is clarified. The physical origin of the deconfinement transition becomes evident in the low energy effective theory induced by the JTM. The proper procedure to compute the fermionic determinant in the presence of Dirac branes will be presented. A byproduct of this approach is the possible appearance of statistical transmutation and the clarification for the different quantization rules for the topological mass.

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arXiv2008

Induced Chern-Simons-like action in Lorentz-violating massless QED

In the present work, we study different aspects of Lorentz and CPT symmetry violation in extended massless QED. By following the observation that the 2+1 dimensional Maxwell-Chern-Simons theory can be originated from the 3+1 dimensional Chern-Simons-like action, we also focus on the fermion sector to relate the 3+1 dimensional extended massless QED to 2+1 dimensional massive QED. We take advantage of this to state that the Chern-Simons-like action in extended massless QED can be induced with its coefficient being well defined and finite just as its 2+1 counterpart. We make use of three different regularization schemes by inducting the Chern-Simons-like in 3+1 dimensions to support this conjecture.

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arXiv2008

Radiative processes as a condensation phenomenon and the physical meaning of deformed canonical structures

Working with well known models in $(2+1)D$ we discuss the physics behind the deformation of the canonical structure of these theories. A new deformation is constructed linking the massless scalar field theory with the self-dual theory. This is the exact dual of the known deformation connecting the Maxwell theory with the Maxwell-Chern-Simons theory. Duality is used to establish a web of relations between the mentioned theories and a physical picture of the deformation procedure is suggested.

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arXiv2008

Induced deformation of the canonical structure and UV/IR duality in $(1+1)D$

The purpose of this work is two fold. Working in the framework of $(1+1)D$ Lorentz violating field theories we will investigate in the first place the general claim that fermionic interactions may be equivalent to a deformation of the canonical structure of the theory. Second the deformed theory will be studied using duality reasoning to address the behavior of the Infra-Red and Ultra-Violet regimes.

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arXiv2007

New formulations for dual equivalent actions

New actions in D=2 and D=3 are proposed that are dual equivalent to known theories displaying well defined chirality and helicity, respectively, along with a new interpolating action that maps continuously through the original dualities. The new chiral action in D=2 is a second-order theory displaying the chiral constraint dynamically while in D=3 the helicity constraint is imposed a la Siegel. The resulting theories introduce new versions of the Hull noton to take care of the symmetry aspects of the original models. The new interpolating formulation is then re-examined as a condensed phase for the discussion of duality under the light of the dual mechanisms -- Julia-Toulouse and Higgs -- establishing new interpolating actions in the dilute phase, according to these mechanisms.

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arXiv2007

Relativistic Green functions in a plane wave gravitational background

We consider a massive relativistic particle in the background of a gravitational plane wave. The corresponding Green functions for both spinless and spin 1/2 cases, previously computed by A. Barducci and R. Giachetti \cite{Barducci3}, are reobtained here by alternative methods, as for example, the Fock-Schwinger proper-time method and the algebraic method. In analogy to the electromagnetic case, we show that for a gravitational plane wave background a semiclassical approach is also sufficient to provide the exact result, though the lagrangian involved is far from being a quadratic one.

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