Strong interactions and topology drive a wide variety of correlated
ground states. Some of the most interesting of these ground states, such
as fractional quantum Hall states and fractional Chern insulators, have
fractionally charged quasiparticles. Correlations in these phases are
captured by the binding of electrons and vortices into emergent particles
called composite fermions. Composite fermion quasiparticles are randomly
localized at high levels of disorder and may exhibit charge order when there
is not too much disorder in the system. However, more complex correlations
are predicted when composite fermion quasiparticles cluster into a bubble,
and then these bubbles order on a lattice. Such a highly correlated ground
state is termed the bubble phase of composite fermions. Here we report
the observation of such a bubble phase of composite fermions, evidenced
by the re-entrance of the fractional quantum Hall effect. We associate this
re-entrance with a bubble phase with two composite fermion quasiparticles
per bubble. Our results demonstrate the existence of a new class of strongly
correlated topological phases driven by clustering and charge ordering of
emergent quasiparticles.
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Fermion pair radiation from accelerating classical systems
Accelerating classical systems that couple to a fermion-antifermion pair at the microscopic level can radiate pairs of fermions and lose energy in the process. In this work, we derive the generalization of the Larmor formula for fermion pair radiation. We focus on the case of a point-like classical source in an elliptical orbit that emits fermions through vector and scalar mediators. Ultra-light fermion emission from such systems becomes relevant when the mass of the mediator is larger than the frequency of the periodic motion. This enables us to probe regions of the parameter space that are inaccessible in on-shell bosonic radiation. We apply our results to pulsar binaries with mediators that couple to muons and neutrinos. Using current data on binary period decays, we extract bounds on the parameters of such models.
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- PAR ID:
- 10467251
- Publisher / Repository:
- Springer Nature
- Date Published:
- Journal Name:
- Journal of High Energy Physics
- Volume:
- 2023
- Issue:
- 10
- ISSN:
- 1029-8479
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1007/JHEP10(2023)002
