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5 votes

Have all the symmetries of the standard model of particle physics been found?

My answer is also ‘No’ but by direct construction: over the past few years, various research groups have understood new symmetries of the Standard Model. Over the past decade, field theorists have ...
SethK's user avatar
  • 589
3 votes
Accepted

$ \pi^0\to \gamma\gamma$ parity conservation

As @Cosmas Zachos said in his comment, the Levi-Civita pseudotensor $\epsilon$ has negative parity. But why? This is the case because $\epsilon_{\mu\nu\rho\sigma} := \sqrt{-g}\ \varepsilon_{\mu\nu\rho\...
Gabriel Ybarra Marcaida's user avatar
2 votes
Accepted

Does electroweak theory have mass gap (not just Higgs mechanism)?

A Higgsed non-Abelian gauge theory has two would-be scales, a spontaneous symmetry breaking scale, and a confinement scale determined by the running of the coupling, analogous to $\Lambda_{QCD}$. ...
octonion's user avatar
  • 8,815
2 votes

How can a virtual $W$ boson turn into an electron and electron antineutrino?

Your question is a result of "just winging it" with quantum field theory. The idea that a $W$ boson with mass $M_W$ is created for a short period of time by borrowing energy via the HUP is ...
JEB's user avatar
  • 35.5k
2 votes
Accepted

Could there be states of matter that could avoid "matter decay"?

Baryon decay can be avoided if you build something out of stable non-baryonic matter. Given our currently known particles that leaves electrons/positrons, and neutrinos. Stable electron clouds are ...
Anders Sandberg's user avatar
1 vote

When is the Lagrangian a Lorentz scalar?

An obvious, kind of dumb, answer is that the Lagrangian corresponding to a given Hamiltonian will be a Lorentz scalar if the Hamiltonian has the form, $$ \mathcal{H} = \pi^a \frac{\partial}{\partial t}...
Josh Newey's user avatar
1 vote

When is the Lagrangian a Lorentz scalar?

As far as I know, there are no good ways of stating what conditions on the Hamiltonian will cause the Lagrangian to be a Lorentz scalar other than to just say the Hamiltonian must be derived from a ...
Travis's user avatar
  • 2,167
1 vote

What force or field is associated with the weak hypercharge?

A clip from wikipedia: Weak hypercharge is the generator of the U(1) component of the electroweak gauge group, SU(2)×U(1) and its associated quantum field B mixes with the W3 electroweak quantum field ...
JEB's user avatar
  • 35.5k

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