Eur. Phys. J. C (2015) 75:238
DOI 10.1140/epjc/s10052-015-3470-1
Regular Article - Theoretical Physics
Topologically massive spin-1 particles and spin-dependent
potentials
F. A. Gomes Ferreira
a
,P.C.Malta
b
, L. P. R. Ospedal
c
, J. A. Helayël-Neto
d
Centro Brasileiro de Pesquisas Físicas (CBPF), Rua Dr Xavier Sigaud 150, Urca, Rio de Janeiro, CEP 22290-180, Brazil
Received: 28 April 2015 / Accepted: 19 May 2015 / Published online: 29 May 2015
© The Author(s) 2015. This article is published with open access at Springerlink.com
Abstract We investigate the role played by particular field
representations of an intermediate massive spin-1 boson
in the context of spin-dependent interparticle potentials
between fermionic sources in the limit of low momentum
transfer. The comparison between the well-known case of
the Proca field and that of an exchanged spin-1 boson (with
gauge-invariant mass) described by a 2-form potential mixed
with a 4-vector gauge field is established in order to pursue
an analysis of spin- as well as velocity-dependent profiles
of the interparticle potentials. We discuss possible applica-
tions and derive an upper bound on the product of vector and
pseudo-tensor coupling constants.
1 Introduction
Most macroscopic phenomena originate either from grav-
itational or electromagnetic interactions. There has been
some experimental effort over the past decades towards the
improvement of low-energy measurements of the inverse-
square law, with fairly good agreement between theory and
experiment [1,2]. The equivalence principle has also been
recently tested to search for a possible spin-gravity coupling
[3]. On the other hand, a number of scenarios beyond the
Standard Model (BSM) motivated by high-energy phenom-
ena predict very light, weakly interacting sub-eV particles
(WISPs) that could generate new long-range forces, such as
axions [4], SUSY-motivated particles [5] or paraphotons [6–
9].
The discovery of a new, though feeble, fundamental
force would represent a remarkable advance. Besides the
Coulomb-like “monopole–monopole” force, it is also pos-
a
e-mail: felipeagf@cbpf.br
b
e-mail: pcmalta@cbpf.br
c
e-mail: leoopr@cbpf.br
d
e-mail: helayel@cbpf.br
sible that spin- and velocity-dependent forces arise from
monopole–dipole and dipole–dipole (spin–spin) interac-
tions. Those types of behavior are closely related to two
important aspects of any interacting field theory: matter–
mediator interaction vertices and the propagator of interme-
diate particles. The present paper is mainly concerned with
this issue and its consequences on the shape of the poten-
tial between two fermionic sources. This discussion is also
of relevance in connection with the study, for example, of
the quarkonium spectrum, for which spin-dependent terms
in the interaction potential may contribute considerable cor-
rections [10]. Other sources (systems) involving neutral and
charged particles, with or without spin, have been considered
by Holstein [11].
Propagators are read off from the quadratic part of a given
Lagrangean density and depend on intrinsic attributes of
the fields, such as their spin. Most of the literature is con-
cerned with spin-1 bosons in the
1
2
,
1
2
-representation of the
Lorentz group (e.g., photon). Here, we would like to address
the following questions: for two different fields represent-
ing the same sort of (on-shell) spin-1 particle, which role
does a particular representation play in the final form of the
interaction? Is the form of the mass term (corresponding to
some specific mass-generation mechanism) determinant for
the macroscopic characterization of the interparticle poten-
tial?
The amplitude for the elastic scattering of two fermions is
sensitive to the fundamental, microscopic, properties of the
intermediate boson. Our work sets out to study the potential
generated by the exchange of two different classes of neutral
particles: a Proca (vector) boson and a rank-2 anti-symmetric
tensor, the Cremer and Scherk [13] and Kalb and Ramond
[12] field, mixed to another vector boson, i.e., the
A
μ
, B
νκ
-
system with a topological mixing term. Two-form gauge
fields are typical of off-shell SUGRA multiplets in four and
higher dimensions [14–18] and the motivation to take them
into consideration is twofold:
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