10,143 research outputs found
The standard electroweak model in the noncommutative space-time
The noncommutative (NC) framework elaborated by Doplicher, Fredenhagen and
Roberts (DFR) has a Lorentz invariant spacetime structure in order to be
considered as a candidate to understand the physics of the early Universe. In
DFR formalism the NC parameter () is a coordinate operator in
an extended Hilbert space and it has a conjugate momentum. Since and
are independent coordinates, the Weyl-Moyal (WM) product can
be used in this framework. With these elements, in this work, we have
constructed the standard electroweak model. To accomplish this task we have
begun with the WM-product basis group of symmetry. After that we have
introduced the spontaneous symmetry breaking and the hypercharge in DFR
framework. The electroweak symmetry breaking was analyzed and the masses of the
new bosons were computed. Finally, the gauge symmetry and gauge transformations
were discussed.Comment: arXiv admin note: text overlap with arXiv:1506.00035,
arXiv:1510.0835
The Yang-Mills gauge theory in DFR noncommutative space-time
The Doplicher-Fredenhagen-Roberts (DFR) framework for noncommutative (NC)
space-times is considered as an alternative approach to describe the physics of
quantum gravity, for instance. In this formalism, the NC parameter, {\it i.e.}
, is promoted to a coordinate of a new extended space-time.
Consequently, we have a field theory in a space-time with spatial
extra-dimensions. This new coordinate has a canonical momentum associated,
where the effects of a new physics can emerge in the fields propagation along
the extra-dimension. In this paper we introduce the gauge invariance in the DFR
NC space-time. We present the non-Abelian gauge symmetry in DFR formalism, and
the consequences of this symmetry in the presence of such extra-dimension. The
gauge symmetry in this DFR scenario can reveal new fields attached to
-extra-dimension. We obtain the propagation of these gauge fields in
terms of canonical momentum associated with -coordinate.Comment: 26 page
An alternative way to explain how non-commutativity arises in the bosonic string theory
In this work we will investigate how the non-commutativity arises into the
string theory, \textit{i.e.}, how the bosonic string theory attaches to a
D3-brane in the presence of magnetic fields. In order to accomplish the
proposal, we departure from the commutative two-dimensional harmonic
oscillator, which after the application of the general Bopp's shifts Matrix
Method, the non-commutative version of the two-dimensional harmonic oscillator
is obtained. After that, this non-commutative harmonic oscillator will be
mapped into the bosonic string theory in the light cone frame, which it now
appears as a bosonic string theory attached to a D3-brane
Noncommutative approach to diagnose degenerate Higgs bosons at 125 GeV
We propose a noncommutative (NC) version for a global O(2) scalar field
theory, whose damping feature is introduced into the scalar field theory
through the NC parameter. In this context, we investigate how noncommutative
drives spontaneous symmetry breaking (SSB) and Higgs-Kibble mechanisms and how
the damping feature workout. Indeed, we show that the noncommutativity plays an
important role in such mechanisms, i.e., the Higgs mass and VEV dependent on NC
parameter. After that, it is explored the consequences of noncommutativity
dependence of Higgs mass and VEV: for the first, it is shown that there are a
mass-degenerate Higgs bosons near 126.5 GeV, parametrized by the
noncommutativity; for the second, the gauge fields gain masses that present a
noncommutativity contribution.Comment: 13 pages, 2 figure
Noncommutative Mapping from the symplectic formalism
The Bopp's shifts will be generalized through symplectic formalism. A special
procedure, like a "diagonalization", which drives the completely deformed
symplectic matrix to the standard symplectic form was found as suggested by
Faddeev-Jackiw. Consequently, the correspondent transformation matrix guides
the mapping from commutative to noncommutative (NC) phase-space coordinates.
The Bopp's shifts may be directly generalized from this mapping. In this
context, all the NC and scale parameters, introduced into the brackets, will be
lifted to the Hamiltonian. Well known results, obtained using -product,
will be reproduced without to consider that the NC parameters are small.
Besides, it will be shown that different choices for NC algebra among the
symplectic variables generates distinct dynamical systems, which they may not
even connect with each other, and that some of them can preserve, break or
restore the symmetry of the system. Further, we will also discuss the charge
and mass rescaling in a simple model.Comment: 24 page
Noncommutative approach to disclose a Higgs group
A noncommutative(NC) version for a global scalar field theory is
proposed and an alternative investigation about how noncommutative drives
spontaneous symmetry breaking (SSB) is explored. Indeed, we show that the
noncommutativity plays an important role in such mechanism, i.e., it is
possible to show that there is a Higgs group with no more than two Higgs
bosons. In this scenario, we establish two mutually exclusive options: one
Higgs boson with mass at 125 GeV and other at 750 GeV -- 2 TeV excess does not
imply a 2 TeV mass resonance -- or two Higgs bosons with mass-degenerate near
125~GeV, where 2 TeV and 750 GeV excesses do not imply a 2 TeV and 750 GeV
masses resonance.Comment: arXiv admin note: text overlap with arXiv:1903.0972
ON THE COVARIANTIZATION OF THE CHIRAL CONSTRAINT
We show that a complete covariantization of the chiral constraint in the
Floreanini-Jackiw necessitates an infinite number of auxiliary Wess-Zumino
fields otherwise the covariantization is only partial and unable to remove the
nonlocality in the chiral boson operator. We comment on recent works that claim
to obtain covariantization through the use of Batalin-Fradkin-Tyutin method,
that uses just one Wess-Zumino field.Comment: Latex, 10 pages, no figure
The protophobic -boson coupled to quantum electrodynamics
The possible origin of an -boson having a mass value around 17 \,
\mbox{MeV} had motivated us to investigate its interaction with leptons of
QED. This new hypothetical particle can possibly be a candidate to describe the
so called fifth interaction, in a new physics scenario beyond the Standard
Model. The model of the -boson interacting with QED is based on a symmetry, where the group is attached to the -boson,
with a kinetic mixing with the photon. The Higgs sector was revisited to
generate the mass for the new boson. Thus, the mass of 17 \, \mbox{MeV} fixes
a vacuum expected value scale. Thereby, we could estimate the mass of the
hidden Higgs field through both the VEV-scale and the Higgs' couplings. A model
of QFT was constructed in a renormalizable gauge, and we analyzed its
perturbative structure. After that, the radiative correction of the -boson
propagator has been calculated at one loop approximation to yield the Yukawa
potential correction. The form factors associated with the QED-vertex
correction were calculated to confirm electron's anomalous magnetic moment
together with the computation of the interaction magnitude. The muon case was
discussed. Furthermore, we have introduced a renormalization group scheme to
explore the current -boson mass and its coupling constant with the leptons
of the Standard Model.Comment: 13 pages, 2 figure
Path integral formalism in a Lorentz invariant noncommutative space
We introduced a new formulation for the path integral formalism for a
noncommutative (NC) quantum mechanics defined in the recently developed
Doplicher-Fredenhagen-Roberts-Amorim (DFRA) NC framework that can be considered
an alternative framework for the NC spacetime of the early Universe. The
operators formalism was revisited and we apply its properties to obtain a NC
transition amplitude representation. Two DFRA's systems were discussed, the NC
free particle and NC harmonic oscillator. Some temperature concepts in this NC
space are also considered. The extension to NC DFRA quantum field theory is
straightforward and we apply it to a massive scalar field. We construct the
generating functional and the effective action to give rise
one-particle-irreducible diagrams. As an example, we set the basis for a
self-interaction to obtain the correction of the
perturbation theory to the propagator and vertex of this model. The main
concept that we would like to emphasize from the outset is that the formalism
demonstrated here will not be constructed introducing a NC parameter in the
system, as usual. It will be generated naturally from an already NC space. In
this extra dimensional NC space, we presented also the idea of dimensional
reduction to recover commutativity.Comment: 21 pages. Pre-print style. Comments welcom
Some aspects of quantum mechanics and field theory in a Lorentz invariant noncommutative space
We obtained the Feynman propagators for a noncommutative (NC) quantum
mechanics defined in the recently developed
Doplicher-Fredenhagen-Roberts-Amorim (DFRA) NC background that can be
considered as an alternative framework for the NC spacetime of the early
Universe. The operators formalism was revisited and we applied its properties
to obtain a NC transition amplitude representation. Two examples of DFRA's
systems were discussed, namely, the NC free particle and NC harmonic
oscillator. The spectral representation of the propagator gave us the NC wave
function and energy spectrum. We calculated the partition function of the NC
harmonic oscillator and the distribution function. Besides, the extension to NC
DFRA quantum field theory is straightforward and we used it in a massive scalar
field. We had written the scalar action with self-interaction using
the Weyl-Moyal product to obtain the propagator and vertex of this model needed
to perturbation theory. %and the effective action to give rise
one-particle-irreducible diagrams. It is important to emphasize from the outset
is that the formalism demonstrated here will not be constructed introducing a
NC parameter in the system, as usual. It will be generated naturally from an
already NC space. In this extra dimensional NC space, we presented also the
idea of dimensional reduction to recover commutativity.Comment: 22 pages. Continuation of 1206.4065 with substantial text overlap.
arXiv admin note: substantial text overlap with arXiv:1206.406
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