44,699 research outputs found
The symmetries of the Dirac--Pauli equation in two and three dimensions
We calculate all symmetries of the Dirac-Pauli equation in two-dimensional
and three-dimensional Euclidean space. Further, we use our results for an
investigation of the issue of zero mode degeneracy. We construct explicitly a
class of multiple zero modes with their gauge potentials.Comment: 22 pages, Latex. Final version as published in JMP. Contains an
additional subsection (4.2) with the explicit construction of multiple zero
mode
Axion Like Particles and the Inverse Seesaw Mechanism
Light pseudoscalars known as axion like particles (ALPs) may be behind
physical phenomena like the Universe transparency to ultra-energetic photons,
the soft -ray excess from the Coma cluster, and the 3.5 keV line. We
explore the connection of these particles with the inverse seesaw (ISS)
mechanism for neutrino mass generation. We propose a very restrictive setting
where the scalar field hosting the ALP is also responsible for generating the
ISS mass scales through its vacuum expectation value on gravity induced
nonrenormalizable operators. A discrete gauge symmetry protects the theory from
the appearance of overly strong gravitational effects and discrete anomaly
cancellation imposes strong constraints on the order of the group. The
anomalous U symmetry leading to the ALP is an extended lepton number and
the protective discrete symmetry can be always chosen as a subgroup of a
combination of the lepton number and the baryon number.Comment: 29pp. v4: published version with erratum. Conclusions unchange
The Two-Nucleon 1S0 Amplitude Zero in Chiral Effective Field Theory
We present a new rearrangement of short-range interactions in the
nucleon-nucleon channel within Chiral Effective Field Theory. This is intended
to reproduce the amplitude zero (scattering momentum 340 MeV) at
leading order, and it includes subleading corrections perturbatively in a way
that is consistent with renormalization-group invariance. Systematic
improvement is shown at next-to-leading order, and we obtain results that fit
empirical phase shifts remarkably well all the way up to the pion-production
threshold. An approach in which pions have been integrated out is included,
which allows us to derive analytic results that also fit phenomenology
surprisingly well.Comment: 34 pages, 7 figure
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