Please circulate.
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Quantum Matter in Mathematics and Physics
https://cmsa.fas.harvard.edu/quantum-matter-seminar/
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Time: May 25, Wed 10:30 -12 ET
Venue: 977347126
https://harvard.zoom.us/j/977347126
Password: cmsa
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Seth Koren (U Chicago)
Baryon Minus Lepton Number BF Theory for the Cosmological Lithium Problem
The cosmological lithium problem---that the observed primordial
abundance is lower than theoretical expectations by order one---is
perhaps the most statistically significant anomaly of SM+ ΛCDM, and
has resisted decades of attempts by cosmologists, nuclear physicists,
and astronomers alike to root out systematics. We upgrade a discrete
subgroup of the anomaly-free global symmetry of the SM to an infrared
gauge symmetry, and UV complete this at a scale Λ as the familiar
U(1)_{B-N_cL} Abelian Higgs theory. The early universe phase
transition forms cosmic strings which are charged under the emergent
higher-form symmetry of the baryon minus lepton BF theory. These
topological defects catalyze interactions which turn N_g baryons into
N_g leptons at strong scale rates in an analogue of the Callan-Rubakov
effect, where N_g=3 is the number of SM generations. We write down a
model in which baryon minus lepton strings superconduct bosonic global
baryon plus lepton number currents and catalyze solely 3p^+ → 3e^+. We
suggest that such cosmic strings have disintegrated O(1) of the
lithium nuclei formed during Big Bang Nucleosynthesis and estimate the
rate, with our benchmark model finding Λ ~ 10^8 GeV gives the right
number density of strings.
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