Finite width induced modification to the electromagnetic form factors of spin-1 particles

Gudiño, D. García; Sánchez, G. Toledo

doi:10.1103/physrevd.81.073006

Cited by 9 publications

(4 citation statements)

References 22 publications

(19 reference statements)

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“…This can be set into the complex mass form times a global factor, which can be absorbed into the normalization of the vector state [6][7][8]:…”

Section: Matching To the Complex Mass Schemementioning

confidence: 99%

“…In figure 4, we exhibit the energy ( q 2 ) behavior of the K * width from the Kp threshold to 1 GeV. The solid line (blue) is the experimental value (PDG), the short dashed line (green) is the width function before corrections, equation (6), and the long dashed line (red) is the width function obtained in this work by bringing the absorptive corrected propagator into the complex mass form, equation (17). Note that, although both energy dependent width functions take the same values at threshold and at the pole, they approach these values in a very different form.…”

Section: Widthmentioning

confidence: 99%

“…G in all the Feynman rules, where Γ is the full decay width. It has been pointed out that there is an equivalence between both approaches [4,6], provided a renormalization of the vector field is invoked [6][7][8]. Throughout this paper, the mass and width parameters in the complex mass scheme are assumed to correspond to the measured ones.…”

Section: Introductionmentioning

confidence: 99%

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Absorptive corrections for vector mesons: matching to complex mass scheme and longitudinal corrections

Pérez

Sánchez

2017

J. Phys. G: Nucl. Part. Phys.

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Unstable spin-1 particles are properly described by including absorptive corrections to the electromagnetic vertex and propagator, without breaking the electromagnetic gauge invariance. We show that the modified propagator can be set into a complex mass form, provided the mass and the width parameters, which are properly defined at the pole position, are replaced by energy dependent functions fulfilling the same requirements at the pole. We exemplify the case for the K * (892) vector meson, where the mass function deviates around 2 MeV from the Kπ threshold to the pole position. The absorptive correction depends on the mass of the particles in the loop. For vector mesons, whose main decay is into two pseudoscalar mesons (P P ′ ), the flavor symmetry breaking induces a correction to the longitudinal part of the propagator. Considering the τ − → K S π − ν τ decay, we illustrate these corrections by obtaining the modified vector and scalar form factors.The K S π − spectrum is described considering the K * (892) and K ′ * (1410) vectors and one scalar particle. Nonetheless, for this case, the correction to the scalar form factor is found to be negligible.

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“…This can be set into the complex mass form times a global factor, which can be absorbed into the normalization of the vector state [6][7][8]:…”

Section: Matching To the Complex Mass Schemementioning

confidence: 99%

Section: Widthmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Absorptive corrections for vector mesons: matching to complex mass scheme and longitudinal corrections

Pérez

Sánchez

2017

J. Phys. G: Nucl. Part. Phys.

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“…Moreover, the lightfront quantum field theory, is the natural theory to describe hadronic bound states, like pseudoscalar particles [15,23,27,28,29,30,31,32,33], or spin half particles [34]. As well, in the last years, some works are dedicate to spin-1 particles, with different approaches [5,8,9,10,24,31,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51]. In addition, some studies of the hadronic properties in the nuclear medium was made in the references [52,53,54,55,56,57,58,59].…”

Section: Introductionmentioning

confidence: 99%

Unambiguous extraction of the electromagnetic form factors for spin-1 particles on the light-front

Melo

2019

Physics Letters B

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The electromagnetic form factors of a composite vector particle within the lightfront formulation of the Mandelstam formula is investigated. In order to extract the form factors from the matrix elements of the plus component of the current in the Drell-Yan frame, where the momentum transfer is chosen such that q + = q 0 +q 3 = 0, one has in principle the freedom to choose between different linear combinations of matrix elements of the current operator. The different prescriptions to calculate the electromagnetic form factors, G 0 , G 1 and G 2 , i.e.; charge form factor, magnetic and quadrupole respectively. If the covariance is respected, all prescriptions give the same results; misfortune, is not the situation; the light-front approach produce different results, which depend of the prescriptions as utilized to extract the electromagnetic form factors in the case of the spin-1 particles. The main differences of the prescriptions appear because of the light-front matrix elements of the electromagnetic current are contaminated by the zero-modes contributions to the same with the plus component of the matrix elements of the electromagnetic current. However, the Inna Grach prescription is immune to the zero-modes contributions to the electromagnetic current, then the electromagnetic form factors extracted with that prescriptions do not have zero-modes contribution and give the same result compared with the instant form quantum field theory. Another's prescriptions with the light-front approach are contaminated by the zero-modes contributions to the matrix elements of the electromagnetic current with the plus component of the current. With some relations between the electromagnetic matrix elements of the electromagnetic current J + ji , as demonstrated analytical here, it was possible to calculate the electromagnetic form factors for spin-1 particles without zero-modes or non-valence contributions.

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Light-front projection of spin-1 electromagnetic current and zero-modes

Melo¹,

Frederico²

2012

Physics Letters B

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The issue of the contribution of zero-modes to the light-front projection of the electromagnetic current of phenomenological models of vector particles vertices is addressed in the Drell-Yan frame. Our analytical model of the Bethe-Salpeter amplitude of a spin-1 fermion-antifermion composite state gives a physically motivated light-front wave function symmetric by the exchange of the fermion and antifermion, as in the ρ-meson case. We found that among the four independent matrix elements of the plus component in the light-front helicity basis only the 0 → 0 one carries zero mode contributions. Our derivation generalizes to symmetric models, important for applications, the above conclusion found for a simplified non-symmetrical form of the spin-1 Bethe-Salpeter amplitude with photon-fermion point-like coupling and also for a smeared fermion-photon vertex model.

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Finite width induced modification to the electromagnetic form factors of spin-1 particles

Cited by 9 publications

References 22 publications

Absorptive corrections for vector mesons: matching to complex mass scheme and longitudinal corrections

Absorptive corrections for vector mesons: matching to complex mass scheme and longitudinal corrections

Unambiguous extraction of the electromagnetic form factors for spin-1 particles on the light-front

Light-front projection of spin-1 electromagnetic current and zero-modes

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