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arXiv · 2201.00123

Tadpoles and vacuum bubbles in light-front quantization

Sophia S. Chabysheva·John R. Hiller
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Abstract

We develop a method by which vacuum transitions may be included in light-front calculations. This allows tadpole contributions which are important for symmetry-breaking effects and yet are missing from standard light-front calculations. These transitions also dictate a nontrivial vacuum and contributions from vacuum bubbles to physical states. In nonperturbative calculations these separate classes of contributions (tadpoles and bubbles) cannot be filtered; instead, we regulate the bubbles and subtract the vacuum energy from the eigenenergy of physical states. The key is replacement of momentum-conserving delta functions with model functions of finite width; the width becomes the regulator and is removed after subtractions. The approach is illustrated in free scalar theory, quenched scalar Yukawa theory, and in a limited Fock-space truncation of $\phi^4$ theory.

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Sophia S. Chabysheva, John R. Hiller. 2022-01-01. Tadpoles and vacuum bubbles in light-front quantization. https://doi.org/10.1103/physrevd.105.116006

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