Physics and Astronomy, Mathematical Physics, Nuclear and High Energy Physics
98
Scopus Publications
Scopus Publications
From Lorentz to SIM(2): contraction, four-dimensional algebraic relations and projective representations J. E. Rodrigues, J. M. B. Matzenbacher, G. M. Caires da Rocha, J. M. Hoff da Silva International Journal of Geometric Methods in Modern Physics, 2026 We present a comprehensive study on [Formula: see text] and [Formula: see text] groups, their representations and algebraic aspects. These groups, together with [Formula: see text], arise as the symmetry groups of Very Special Relativity (VSR), where full Lorentz invariance is reduced while retaining many relativistic consequences. After obtaining [Formula: see text] through the Inönü–Wigner contraction procedure, a complete four-dimensional algebraic representation is shown for [Formula: see text] and [Formula: see text]. Besides that, we apply Bargmann’s formalism to investigate the (projective) representations for both cases, keeping track of the source of phase factors. We complete the study by presenting a particularly simple analysis to probe the existence of local phase factors, which is useful when dealing with non-abelian groups.
Breaking the permutation character of diffeomorphisms on spinor structures J. M. Hoff da Silva Modern Physics Letters A, 2025 In this paper, we investigate the impact of diffeomorphisms, where more than one nonequivalent spinor structure is built upon a given base manifold endowed with nontrivial topology. We call attention to the fact that a relatively straightforward construction evinces a lack of symmetry between fermionic modes from different spinor bundle sections, leading to a dynamic preference breaking the permutation character of diffeomorphisms on spinor structures.
A note on hidden classes in spinor classification R. J. Bueno Rogerio, R. T. Cavalcanti, C. H. Coronado Villalobos, J. M. Hoff da Silva Proceedings of the Royal Society A Mathematical Physical and Engineering Sciences, 2025 The Lounesto classification is a well-established scheme for categorizing spinors based on their physical content, determined by their associated bilinear forms. It consists of six disjoint classes encompassing the known spinors within the context of the standard model of high-energy physics. However, advancements in theories beyond the standard model have opened the door to potential new spinorial adjoint structures, leading to new unforeseen classes. These developments indicate the potential for extending the standard Lounesto classification. This paper explores all possible subclasses that could extend the Lounesto scheme. We highlight the most relevant subclasses by imposing constraints on their corresponding dual structures, thus broadening our understanding of spinors and their applications in theoretical physics.
Deformations in spinor bundles: Lorentz violation and further physical implications J M Hoff da Silva, R T Cavalcanti, G M Caires da Rocha Journal of Physics A Mathematical and Theoretical, 2025 This paper delves into the deformation of spinor structures within nontrivial topologies and their physical implications. The deformation is modeled by introducing real functions that modify the standard spinor dynamics, leading to distinct physical regions characterized by varying degrees of Lorentz symmetry violation. It allows us to investigate the effects in the dynamical equation and a geometrized nonlinear sigma model. The findings suggest significant implications for the spinor fields in regions with nontrivial topologies, providing a robust mathematical approach to studying exotic spinor behavior.
Enlargement of Symmetry Groups in Physics: A Practitioner’s Guide Lehel Csillag, Julio Marny Hoff da Silva, Tudor Pătuleanu Universe, 2024 Wigner’s classification has led to the insight that projective unitary representations play a prominent role in quantum mechanics. The physics literature often states that the theory of projective unitary representations can be reduced to the theory of ordinary unitary representations by enlarging the group of physical symmetries. Nevertheless, the enlargement process is not always described explicitly: it is unclear in which cases the enlargement has to be conducted on the universal cover, a central extension, or a central extension of the universal cover. On the other hand, in the mathematical literature, projective unitary representations have been extensively studied, and famous theorems such as the theorems of Bargmann and Cassinelli have been achieved. The present article bridges the two: we provide a precise, step-by-step guide on describing projective unitary representations as unitary representations of the enlarged group. Particular focus is paid to the difference between algebraic and topological obstructions. To build the bridge mentioned above, we present a detailed review of the difference between group cohomology and Lie group cohomology. This culminates in classifying Lie group central extensions by smooth cocycles around the identity. Finally, the take-away message is a hands-on algorithm that takes the symmetry group of a given quantum theory as input and provides the enlarged group as output. This algorithm is applied to several cases of physical interest. We also briefly outline a generalization of Bargmann’s theory to time-dependent phases using Hilbert bundles.
Emergent Spinor Fields from Exotic Spin Structures J M Hoff da Silva, R da Rocha Progress of Theoretical and Experimental Physics, 2024 The classification of emergent spinor fields according to modified bilinear covariants is scrutinized in space-times with nontrivial topology, which induce inequivalent spin structures. Extended Clifford algebras, constructed by equipping the underlying space-time with an extended bilinear form with additional terms coming from the nontrivial topology, naturally yield emergent extended algebraic spinor fields and their subsequent extended bilinear covariants, which are contrasted to the classical spinor classification. An unexpected duality between the standard and the exotic spinor field classes is therefore established, showing that a complementary fusion process among the spinor field classes sets in, when extended Clifford bundles are addressed in multiply connected space-times.
Irreducible representations of the Poincaré group with reflections and two-fold Wigner degeneracy Dharam Vir Ahluwalia, G. B. de Gracia, Julio M. Hoff da Silva, Cheng-Yang Lee, B. M. Pimentel Journal of High Energy Physics, 2024 Not all complete set of spinors can be used as expansion coefficients of a quantum field. In fact, Steven Weinberg established the uniqueness of Dirac spinors for this purpose provided: (a) one paid due attention to the multiplicative phases for each of the spinors, and (b) one paired these to creation and annihilation operators in a specific manner. This is implicit in his implementation of the rotational symmetry for the spin half quantum field. Among the numerous complete set of spinors that are available to a physicist, Elko occupies a unique status that allows it to enter as expansion coefficients of a quantum field without violating Weinberg’s no go theorem. How this paradigm changing claim arises is the primary subject of this communication. Weinberg’s no go theorem is evaded by exploiting a uniquely special feature of Elko that allows us to introduce a doubling of the particle-antiparticle degrees of freedom from four to eight. Weinberg had dismissed this degeneracy on the ground that, “no examples are known of particles that furnish unconventional representations of inversions.” Here we will find that this degeneracy, once envisioned by Eugene Wigner, in fact gives rise to a quantum field that has all the theoretical properties required of dark matter.
Non-standard Wigner doublets F. A. da Silva Barbosa, J. M. Hoff da Silva Epl, 2023 Guided by a conservative formulation in investigating the physical content of quantum fields, we explore non-standard Wigner classes of particles that could provide the basis for self-interaction models to dark matter. We critically contrast the analysis with long-standing constraints to non-standard Wigner classes in the literature to discuss the model's viability.
Perturbative aspects of mass dimension one fermions non-minimally coupled to electromagnetic field Willian Carvalho, M. Dias, A. C. Lehum, J. M. Hoff da Silva Epl, 2023 This paper addresses perturbative aspects of the renormalization of a fermion with mass dimension one non-minimally coupled to the electromagnetic field. Specifically, we calculate the one-loop corrections to the propagators and vertex functions of the model and determine the one-loop beta function of the non-minimal electromagnetic coupling. Additionally, we perform calculations of the two-loop corrections to the gauge field propagator, demonstrating that it remains massless and transverse up to this order. We also find that the non-minimal electromagnetic coupling can exhibit asymptotic freedom if a certain condition is satisfied. As a potential dark matter candidate, these findings suggest that the field may decouple at high energies. This aspect holds significance for calculating the relic abundance and freeze-out temperature of the field, particularly in relation to processes involving the ordinary particles of the Standard Model.
Regular spinors and fermionic fields R.J. Bueno Rogerio, J.M. Hoff da Silva, C.H. Coronado Villalobos Physics Letters Section A General Atomic and Solid State Physics, 2021
Friedmann–Lemaître–Robertson–Walker braneworlds P. Michel L.T. da Silva, A. de Souza Dutra, J.M. Hoff da Silva Physics Letters Section B Nuclear Elementary Particle and High Energy Physics, 2017
Method for obtaining thick brane models A. de Souza Dutra, G. P. de Brito, J. M. Hoff da Silva Physical Review D Particles Fields Gravitation and Cosmology, 2015
Exploring Elko typical signature M. Dias, F. de Campos, J.M. Hoff da Silva Physics Letters Section B Nuclear Elementary Particle and High Energy Physics, 2012
