L7.2 Higgs Physics: Fermion Masses | Summary and Q&A

2.0K views
June 24, 2021
by
MIT OpenCourseWare
YouTube video player
L7.2 Higgs Physics: Fermion Masses

TL;DR

The Higgs mechanism explains how gauge bosons acquire mass through the Higgs field, but fermions require a different solution.

Install to Summarize YouTube Videos and Get Transcripts

Key Insights

  • 💆 The Higgs mechanism explains how gauge bosons acquire mass, but a different solution is needed for fermions.
  • ↔️ Fermions interact with the Higgs field to acquire mass, with left-handed fermions becoming right-handed and vice versa.
  • 💆 The mass of fermions is determined by the strength of their Yukawa coupling to the Higgs field.
  • 🙂 The Higgs mechanism provides a way to explain the broad spectrum of fermion masses, ranging from the heaviest top quark to the lightest electron.
  • ❓ Neutrinos, which are fermions, also have masses, but their masses have not yet been fully understood or measured.
  • 👻 The introduction of terms into the Lagrangian equation allows for the interaction between fermions and the Higgs field.
  • 🥶 Each fermion has its own Yukawa coupling, which serves as a free parameter in the standard model.

Transcript

MARKUS KLUTE: Welcome back to 8.701. In the previous lecture, we have seen how the gauge bosons, the W, and the Z boson acquire mass, while the photon remains massless, through the Higgs mechanism. We introduced a new field, a new complex doublet field, the Higgs field, which then broke, through its vacuum expectation value, the symmetry. And then ... Read More

Questions & Answers

Q: How do gauge bosons acquire mass through the Higgs mechanism?

Gauge bosons, such as the W and Z bosons, acquire mass through their coupling to the Higgs field's vacuum expectation value, which breaks the symmetry and gives them mass.

Q: Why can't fermions have mass added to their Lagrangian equation?

Adding mass to the fermion Lagrangian would violate gauge invariance. Fermions require a different solution to acquire mass.

Q: How do fermions acquire mass according to the Higgs mechanism?

Fermions acquire mass through their interaction with the Higgs field. The interaction turns left-handed fermions into right-handed fermions and vice versa.

Q: Are all fermions described by the same Yukawa coupling?

No, each fermion has its own Yukawa coupling, which is a free parameter in the standard model. The Yukawa coupling determines the strength of the fermion's interaction with the Higgs field and, consequently, its mass.

Summary & Key Takeaways

  • The Higgs mechanism explains how gauge bosons acquire mass through the Higgs field's vacuum expectation value.

  • Fermions cannot simply have mass added to their Lagrangian equation because it would violate gauge invariance.

  • Fermions interact with the Higgs field, which turns them into right-handed particles, and this interaction is described by Yukawa couplings.

Share This Summary 📚

Summarize YouTube Videos and Get Video Transcripts with 1-Click

Download browser extensions on:

Explore More Summaries from MIT OpenCourseWare 📚

Summarize YouTube Videos and Get Video Transcripts with 1-Click

Download browser extensions on: