15,110 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
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
Measuring the phase of the scattering amplitude with vortex beams
We show that colliding vortex beams instead of (approximate) plane waves can
lead to a direct measurement of how the overall phase of the plane wave
scattering amplitude changes with the scattering angle. Since vortex beams are
coherent superpositions of plane waves with different momenta, their scattering
amplitude receives contributions from plane wave amplitudes with distinct
kinematics. These contributions interfere, leading to the measurement of their
phase difference. Although interference exists for any generic wave packet
collision, we show that using vortex beams dramatically enhances sensitivity to
the phase in comparison with non-vortex beams. Since the overall phase is
inaccessible in a plane wave collision, this measurement would be of great
importance for a number of topics in hadronic physics, for example, meson
production in the resonance region, physics of nucleon resonances, and small
angle elastic hadron scattering.Comment: 18 pages, 5 figures; v2: introduction rewritten and expanded, matches
the published versio
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