15,433 research outputs found
Z_p scalar dark matter from multi-Higgs-doublet models
In many models, stability of dark matter particles is protected by a
conserved Z_2 quantum number. However dark matter can be stabilized by other
discrete symmetry groups, and examples of such models with custom-tailored
field content have been proposed. Here we show that electroweak symmetry
breaking models with N Higgs doublets can readily accommodate scalar dark
matter candidates stabilized by groups Z_p with any , leading to
a variety of kinds of microscopic dynamics in the dark sector. We give examples
in which semi-annihilation or multiple semi-annihilation processes are allowed
or forbidden, which can be especially interesting in the case of asymmetric
dark matter.Comment: 10 page
Minkowski space structure of the Higgs potential in 2HDM
The Higgs potential of 2HDM keeps its generic form under the group of
transformation GL(2,C), which is larger than the usually considered
reparametrization group U(2). This reparametrization symmetry induces the
Minkowski space structure in the orbit space of 2HDM. Exploiting this property,
we present a geometric analysis of the number and properties of stationary
points of the most general 2HDM potential. In particular, we prove that
charge-breaking and neutral vacua never coexist in 2HDM and establish
conditions when the most general explicitly CP-conserving Higgs potential has
spontaneously CP-violating minima. Our analysis avoids manipulation with
high-order algebraic equations.Comment: 33 pages, 6 figures; v3: corrected a flaw in the proof of proposition
1
Colliding particles carrying non-zero orbital angular momentum
Photons carrying non-zero orbital angular momentum (twisted photons) are
well-known in optics. Recently, it was suggested to use Compton backscattering
to boost optical twisted photons to high energies. Twisted electrons in the
intermediate energy range have also been produced recently. Thus, collisions
involving energetic twisted particles seem to be feasible and represent a new
tool in high-energy physics. Here we discuss some generic features of
scattering processes involving twisted particles in the initial and/or final
state. In order to avoid additional complications arising from non-trivial
polarization states, we focus here on scalar fields only. We show that
processes involving twisted particles allow one to perform a Fourier analysis
of the plane wave cross section with respect to the azimuthal angles of the
initial particles. In addition, using twisted states one can probe the
autocorrelation function of the amplitude, which is inaccessible in the plane
wave collisions. Finally, we discuss prospects for experimental study of these
effects.Comment: v2: 24 pages, 2 figures; merged with arXiv:1101.1630 and matches the
published versio
Creation of two vortex-entangled beams in a vortex beam collision with a plane wave
Physics of photons and electrons carrying orbital angular momentum (OAM) is
an exciting field of research in quantum optics and electron microscopy.
Usually, one considers propagation of these vortex beams in a medium or
external fields and their absorption or scattering on fixed targets. Here we
consider instead a beam-beam collision. We show that elastic scattering of a
Bessel vortex beam with a counterpropagating plane wave naturally leads to two
vortex-entangled outgoing beams. The vortex entanglement implies that the two
final particles are entangled not only in their orbital helicities but also in
opening angles of their momentum cones. Our results are driven by kinematics of
vortex-beam scattering and apply to particle pairs of any nature: e-gamma,
e^+e^-, ep, etc. This collisional vortex entanglement can be used to create
pairs of OAM-entangled particles of different nature, and to transfer a phase
vortex, for example, from low-energy electrons to high-energy protons.Comment: 4 pages, 2 figures; v2: title modified, introduction rewritten and
expanded, results unchange
Properties of the general NHDM. II. Higgs potential and its symmetries
We continue our analysis of the general N-Higgs-doublet model and focus of
the Higgs potential description in the space of gauge orbits. We develop a
geometric technique that allows us to study the global minimum of the potential
without explicitly finding its position. We discuss symmetry patterns of the
NHDM potential, and illustrate the general discussion with various specific
variants of the three-Higgs-doublet model.Comment: 28 pages, 9 figures; v2: introduction rewritten, matches the
published versio
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