24,206 research outputs found

    Z_p scalar dark matter from multi-Higgs-doublet models

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    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 p≤2N−1p \le 2^{N-1}, 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

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    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

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    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

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    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

    Creation of two vortex-entangled beams in a vortex beam collision with a plane wave

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    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
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