Charge Asymmetry of Muons Generated by Laser- Induced Nuclear Processes in Ultra-dense Hydrogen D(0) and p(0)

Laser-induced nuclear reactions in ultra-dense hydrogen H(0) (review in Physica Scripta 2019) give mesons (kaons and pions) which decay to muons. The process which gives the mesons is baryon annihilation (Holmlid, J. Hydrogen Energy 2021; Holmlid and Olafsson, High Energy Density Phys. 2021). The sign of the muons detected depends on the initial baryons, with D(0) in the meson source producing mainly positive muons and p(0) producing mainly negative muons. This charge asymmetry was reported in Holmlid and Olafsson (Heliyon 2019), and has been confirmed by later experiments with a coil current transformer as beam detector , also in another lab (unpublished). The current coil detector would give no signal from the muons if charge symmetry existed. The charge asymmetry of the muons seems first to be at variance with charge conservation. An analysis of the results which includes charge conservation is given here. It agrees with the standard model of particle physics. Using D(0), the asymmetry is, as previously, proposed to be due to capture of µ- in D atoms and D2 molecules. This gives emission of mainly µ+ and a fraction of > 50% of µ+ from D(0). In p(0), the capture rate of µ- is lower than in D(0). The emitted number of µ+ will be decreased by reaction between µ+ and abundant electrons, forming muonium particles. This effect decreases the fraction of emitted µ+ for both p(0) and D(0), and it is proposed to be the main reason for a larger fraction of emitted µ- in the case of p(0).

Topological violation of global symmetries in quantum gravity

We discuss a topological reason why global symmetries are not conserved in quantum gravity, at least when the symmetry comes from compactification of a higher form symmetry. The mechanism is purely topological and does not require any explicit breaking term in the UV Lagrangian. Local current conservation does not imply global charge conservation in a sum over geometries in the path integral. We explicitly consider the shift symmetry of an axion-like field which originates from the compactification of a p-form gauge field. Our topological construction is motivated by the brane/black-brane correspondence, brane instantons, and an idea that virtual black branes of a simple kind may be realized by surgery on spacetime manifolds.

Evolution and global charge conservation for polarization singularities emerging from non-Hermitian degeneracies

Core concepts in singular optics, especially the polarization singularities, have rapidly penetrated the surging fields of topological and non-Hermitian photonics. For open photonic structures with non-Hermitian degeneracies in particular, polarization singularities would inevitably encounter another sweeping concept of Berry phase. Several investigations have discussed, in an inexplicit way, connections between both concepts, hinting at that nonzero topological charges for far-field polarizations on a loop are inextricably linked to its nontrivial Berry phase when degeneracies are enclosed. In this work, we reexamine the seminal photonic crystal slab that supports the fundamental two-level non-Hermitian degeneracies. Regardless of the invariance of nontrivial Berry phase (concerning near-field Bloch modes defined on the momentum torus) for different loops enclosing both degeneracies, we demonstrate that the associated far polarization fields (defined on the momentum sphere) exhibit topologically inequivalent patterns that are characterized by variant topological charges, including even the trivial scenario of zero charge. Moreover, the charge carried by the Fermi arc actually is not well defined, which could be different on opposite bands. It is further revealed that for both bands, the seemingly complex evolutions of polarizations are bounded by the global charge conservation, with extra points of circular polarizations playing indispensable roles. This indicates that although not directly associated with any local charges, the invariant Berry phase is directly linked to the globally conserved charge, physical principles underlying which have all been further clarified by a two-level Hamiltonian with an extra chirality term. Our work can potentially trigger extra explorations beyond photonics connecting Berry phase and singularities.