4 research outputs found
SM fermion scattering off electric charge and CP-violating domain walls in the 2HDM
In several models of beyond Standard Model physics (BSM) discrete symmetries
play an important role. For instance, in order to avoid flavor changing neutral
currents (FCNC), a discrete symmetry is imposed on
Two-Higgs-Doublet-Models (2HDM). This can lead to the formation of domain walls
(DW) as the symmetry gets spontaneously broken during electroweak
symmetry breaking (EWSB) in the early universe. Due to this simultaneous
spontaneous breaking of both the discrete symmetry and the electroweak
symmetry, the vacuum manifold has the structure of two disconnected 3-spheres
and the formed domain walls can exhibit several special properties in contrast
to standard domain walls. We focus on some of these properties such as CP and
electric charge violating vacua localized inside the domain walls. The breaking
of inside the wall leads to the known phenomenon of
"clash-of-symmetries" mechanism, meaning that the symmetry group inside the
wall is smaller than the symmetry group far from the wall. We also discuss the
scattering of top quarks off such types of domain walls and show, for example,
that they can be reflected or transmitted off the wall as a bottom quark.Comment: 7 pages, 3 figures, Contribution to the proceedings of the European
Physical Society Conference on High Energy Physics (EPS-HEP2023), 21-25
August 2023, Hamburg, German
Domain walls in the Two-Higgs-Doublet Model and their charge and CP-violating interactions with Standard Model fermions
Discrete symmetries play an important role in several extensions of the
Standard Model (SM) of particle physics. For instance, in order to avoid flavor
changing neutral currents, a discrete symmetry is imposed on the
Two-Higgs-Doublet Model (2HDM). This can lead to the formation of domain walls
(DW) as the symmetry gets spontaneously broken during electroweak
symmetry breaking in the early universe and domain walls form between regions
whose vacua are related by the discrete symmetry. Due to this simultaneous
spontaneous breaking of both the discrete symmetry and the electroweak
symmetry, the vacuum manifold consists of two disconnected 3-spheres. Such a
non-trivial disconnected vacuum manifold leads to several choices for the vacua
at two adjacent regions, in contrast to models where only the discrete symmetry
gets spontaneously broken and the vacuum manifold consists of several
disconnected points. Due to this, we end up with several classes of DW
solutions having different properties localized inside the wall, such as charge
and/or CP violating vacua. We discuss the properties of these different classes
of DW solutions as well as the interaction of SM fermions with such topological
defects leading to different exotic phenomena such as, for example, the top
quark being transmitted or reflected off the wall as a bottom quark.Comment: 65 pages, 50 figures, 2 table
The dipole formalism for massive initial-state particles and its application to dark matter calculations
The dark matter abundance plays a crucial role in the determination of the
valid parameter space of models both in case of a discovery of dark matter and
in the context of exclusion limits. Reliable theoretical predictions of the
dark matter relic density require technically demanding precision calculations,
which were so far limited in their automation due to challenges in the
treatment of infrared divergences appearing in higher order calculations. In
particular, massive initial states need to be considered in early Universe
computations, so that the known dipole subtraction methods could not be
directly exploited. We therefore provide a full generalization of the dipole
subtraction method by Catani and Seymour to (SUSY)-QCD with massive initial
states. All dipole splitting functions and their integrated counterparts are
given explicitly for four different dimensional schemes. To showcase their
application, we apply our results to dark matter (co)-annihilation processes in
the context of the Minimal Supersymmetric (SUSY) Standard Model (MSSM). We also
demonstrate the accuracy of the dipole method by comparing our numerical
results with those obtained with the space space slicing method. Our analytical
results will facilitate future automation of dark matter abundance calculations
at next-to-leading order for both SUSY and non-SUSY models.Comment: 42 pages, 8 figures, 3 table