Spin- $ {\frac{{3}}{{2}}}$ beyond the Rarita-Schwinger framework

Napsuciale, M.; Kirchbach, Mariana; Rodríguez, Simón

doi:10.1140/epja/i2005-10315-8

Cited by 54 publications

(130 citation statements)

References 41 publications

(77 reference statements)

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“…For illustrative purposes we here recall the form of such a projector for the (1/2, 1/2)⊗[(1/2, 0)⊕(0, 1/2)] representation (four-vector-spinor representation in the following) whose wave function, ψ µ , has 16 degrees of freedom distributed over one spin-3/2, and two spin-1/2 fermions of opposite parities. In this case, one finds [3],…”

Section: Covariant Projector Formalism and Electromagnetic Currentsmentioning

confidence: 97%

“…Notice that P (m, 3 2 ) is a 16 × 16 dimensional four-vector-spinor object which carries two Lorentz indices, as usually denoted by lowercase Greek letters, and two Dirac-spinor labels, to be here denoted by capital Latin letters. Subsequently, as explained in [3], the wave equation for ψ µ can be cast in the most general covariant form according to, 2) and in terms of the Lorentz tensor Γ ABαη;µν , carrying four covariant-, and two spinor indices. In the labeling of the Γ tensor we placed a semi-colon as a demarcation sign between the Lorentz indices of the tensor which contract with the Lorentz indices of the four-vector representation, and those which contract with the two derivatives.…”

Section: Covariant Projector Formalism and Electromagnetic Currentsmentioning

confidence: 99%

“…In the labeling of the Γ tensor we placed a semi-colon as a demarcation sign between the Lorentz indices of the tensor which contract with the Lorentz indices of the four-vector representation, and those which contract with the two derivatives. The explicit form of Γ ABαη;µν has been worked out in [3] and will be presented again in due place below. For the time being, suffice to recall that Γ ABαη;µν can be split into a symmetric (SYM) and an anti-symmetric (AS) tensor, according to 3) and that in the absence of interactions, the Γ AS ABαη;µν term does not provide any contribution.…”

Section: Covariant Projector Formalism and Electromagnetic Currentsmentioning

confidence: 99%

“…The explicit form of Γ ABαη;µν has been worked out in [3] and will be presented again in due place below. For the time being, suffice to recall that Γ ABαη;µν can be split into a symmetric (SYM) and an anti-symmetric (AS) tensor, according to 3) and that in the absence of interactions, the Γ AS ABαη;µν term does not provide any contribution. In order to verify this, we drop the Dirac spinor indices, and the mass and spin labels as well, in which case (2.2) becomes more transparent,…”

Section: Covariant Projector Formalism and Electromagnetic Currentsmentioning

confidence: 99%

“…Subsequently, we will occasionally refer to the Poincaré covariant second order projector formalism developed in [3] as NKR formalism, for brevity. Towards our goal, the description of the electromagnetic multipole moments of particles with spin-1/2, spin-1, and spin-3/2, we present below expressions for the respective electromagnetic currents as they emerge within the NKR formalism.…”

Section: Covariant Projector Formalism and Electromagnetic Currentsmentioning

confidence: 99%

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Electromagnetic multipole moments of elementary spin-1/2, 1, and3/2particles

et al. 2012

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We study multipole decompositions of the electromagnetic currents of spin-1/2, 1, and 3/2 particles described in terms of representation specific wave equations which are second order in the momenta and which emerge within the recently elaborated Poincaré covariant projector method, where the respective Lagrangians explicitly depend on the Lorentz group generators of the representations of interest. The currents are then the ordinary linear Noether currents related to phase invariance, and present themselves always as two-terms motion-plus spin-magnetization currents. The spin-magnetization currents appear weighted by the gyromagnetic ratio, g, a free parameter in the method which we fix either by unitarity of forward Compton scattering amplitudes in the ultraviolet for spin-1, and spin-3/2, or, in the spin-1/2 case, by their asymptotic vanishing, thus ending up in all three cases with the universal g value of g = 2. Within the method under discussion we calculate the electric multipoles of the above spins for the spinor-, the four-vector, and the fourvector-spinor representations, and find it favorable in some aspects specifically in comparison with the conventional Proca-, and Rarita-Schwinger frameworks. We furthermore attend to the most general non-Lagrangian spin-3/2 currents which are allowed by Lorentz invariance to be up to third order in the momenta and construct the linear-current equivalent of identical multipole moments of one of them. We conclude that non-linear non-Lagrangian spin-3/2 currents are not necessarily more general and more advantageous than the linear spin-3/2 Lagrangian current emerging within the covariant projector formalism. Finally, we test the representation dependence of the multipoles by placing spin-1 and spin-3/2 in the respective (1,0)⊕(0,1), and (3/2,0)⊕(0,3/2) single-spin representations. We observe representation independence of the charge monopoles and the magnetic dipoles, in contrast to the higher multipoles, which turn out to be representation dependent. In particular, we find the bi-vector (1, 0) ⊕ (0, 1) to be characterized by an electric quadrupole moment of opposite sign to the one found in (1/2, 1/2), and consequently, to the W boson. This observation allows to explain the positive electric quadrupole moment of the ρ meson extracted from recent analyzes of the ρ meson electric form factor. Our finding points toward the possibility that the ρ meson could transform as part of an anti-symmetric tensor with an a1 meson-like state as its representation companion, a possibility consistent with the empirically established ρ-, and a1 vector meson dominance of the hadronic vector-, and axial-vector currents.

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Section: Covariant Projector Formalism and Electromagnetic Currentsmentioning

confidence: 97%

Section: Covariant Projector Formalism and Electromagnetic Currentsmentioning

confidence: 99%

Section: Covariant Projector Formalism and Electromagnetic Currentsmentioning

confidence: 99%

Section: Covariant Projector Formalism and Electromagnetic Currentsmentioning

confidence: 99%

Section: Covariant Projector Formalism and Electromagnetic Currentsmentioning

confidence: 99%

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Electromagnetic multipole moments of elementary spin-1/2, 1, and3/2particles

et al. 2012

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Renormalization of the QED of self-interacting second order spin $ \frac{1}{2} $ fermions.

Vaquera-Araujo

Napsuciale

Ángeles-Martínez

2013

J. High Energ. Phys.

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We study the one-loop level renormalization of the electrodynamics of spin 1/2 fermions in the Poincaré projector formalism, in arbitrary covariant gauge and including fermion self-interactions, which are dimension four operators in this framework. We show that the model is renormalizable for arbitrary values of the tree level gyromagnetic factor g within the validity region of the perturbative expansion, αg 2 ≪ 1. In the absence of tree level fermion self-interactions, we recover the pure QED of second order fermions, which is renormalizable only for g = ±2. Turning off the electromagnetic interaction we obtain a renormalizable Nambu-Jona-Lasinio-like model with second order fermions in four space-time dimensions.

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Higher-spin particles at high-energy colliders

Criado

Djouadi

Koivunen

et al. 2021

J. High Energ. Phys.

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Using an effective field theory approach for higher-spin fields, we derive the interactions of colour singlet and electrically neutral particles with a spin higher than unity, concentrating on the spin-3/2, spin-2, spin-5/2 and spin-3 cases. We compute the decay rates and production cross sections in the main channels for spin-3/2 and spin-2 states at both electron-positron and hadron colliders, and identify the most promising novel experimental signatures for discovering such particles at the LHC. The discussion is qualitatively extended to the spin-5/2 and spin-3 cases. Higher-spin particles exhibit a rich phenomenology and have signatures that often resemble the ones of supersymmetric and extra-dimensional theories. To enable further studies of higher-spin particles at collider and beyond, we collect the relevant Feynman rules and other technical details.

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Spin- $ {\frac{{3}}{{2}}}$ beyond the Rarita-Schwinger framework

Cited by 54 publications

References 41 publications

Electromagnetic multipole moments of elementary spin-1/2, 1, and3/2particles

Electromagnetic multipole moments of elementary spin-1/2, 1, and3/2particles

Renormalization of the QED of self-interacting second order spin $ \frac{1}{2} $ fermions.

Higher-spin particles at high-energy colliders

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