Question
The “bare” form of this specific quantity was first renormalized in a 1947 calculation that Hans Bethe purportedly did on a train ride to Schenectady (skuh-NECK-tuh-dee). For 10 points each:
[10h] Name this quantity, whose “bare” form is a parameter in the Q·E·D Lagrangian. A process by which a photon is emitted and re-absorbed has a divergent energy, necessitating the renormalization of this quantity.
ANSWER: mass of an electron [or electron mass; accept positron mass; accept mass-energy in place of mass; prompt on bare mass by asking, “of what particle?”]
[10e] The self-energy of an electron can be visualized as a 1-loop one of these drawings. In these drawings, photons are represented by wavy lines.
ANSWER: Feynman diagrams
[10m] Photon self-energy involves the creation of virtual electron-positron pairs, which causes the “polarization” of this quantum state. In Fock space, this state is often written simply as “ket zero.”
ANSWER: vacuum state [accept vacuum polarization]
<JF, Physics>
Summary
| 2023 ARCADIA at UC Berkeley | Premiere | Y | 1 | 20.00 | 100% | 100% | 0% |
| 2023 ARCADIA at RIT | Premiere | Y | 1 | 10.00 | 100% | 0% | 0% |
Data
| Berkeley A | Stanford A | 0 | 10 | 10 | 20 |