Questions tagged [particle-physics]
Particle physics is the study of the fundamental forces of nature as they are embodied in the interactions of elementary and composite particles at high energies and short time and distance scales. DO NOT USE THIS TAG for point particles in classical mechanics.
6,807 questions
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Do spin correlations between $b$ and $\bar b$ exist at all in $H \to b\bar b$, and can they survive parton showering?
I'm studying the CP structure of $H \to b\bar b$. At generator level (with parton showering on), any spin correlation between the $b$ and $\bar b$ branches seems completely washed out — even when ...
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Does the universe try to attain "homeostasis"? [closed]
I know locally, matter cannot be created nor destroyed. I am wondering how in the bigger picture the universe expands, and I am guessing more energy. Is the energy of these systems always trying to ...
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The Twin Particle Theory [closed]
Imagine that particles exist like twins — not just connected through quantum entanglement, but through something deeper, maybe even a form of consciousness. Everything is connected, not by space or ...
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Does the structure of the laws of physics allow for the discovery of a 5th fundamental force?
Does the structure of the laws of physics allow for the discovery of a 5th fundamental force? Would the discovery of a fifth fundamental force require the complete rewriting of what everything we know ...
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Infrared zeromodes and the physical status of infinite-wavelength photons in quantum field theory
In quantum field theory, photons are described as quantized excitations of the electromagnetic field, with energy given by $E = ℏω = hc/λ$. In the infrared (IR) limit, where the wavelength $λ$ tends ...
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Measurement of (intrinsic) electric quadrupole moment of neutron?
While there are amazing experimental boundaries for electric dipole moment of electron and neutron, for electric quadrupole moments I could only find for large nuclei. It seems especially interesting ...
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What causes a spin flip transition from a ground state to an excited state?
I was reading about radio astronomy and I wanted to understand why electrically neutral hydrogen emits radio waves. The Wikipedia page for the Hydrogen Line says that a photon at the 21cm frequency is ...
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When should one consider parity and charge conjugation and how does it work?
As written above the main question is: How does parity and C-parity work and when do I need to consider it? I feel like parity and $C$-parity is not very well defined. I know for parity that it's a ...
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Particle Transmissions of E&M Fields
Recently, in my Calc based physics course we have begun to be introduced to the concept of magnetic fields. The way we have had it described is that magnetic fields are generated by and interact with ...
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Dividing multi-particle states into a sum of states with particles of definite number
In Peskin & Schroeder's book (7.1 , p212) in the studying of the analytic structure of two-point correlation function, they generalize the completeness relationship of 1 particle states $$ \left( ...
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Scaling the field values for the Higgs potential
In Toward the Theory of Electroweak Phase Transition by Dine, Leigh, et.al. The zero temperature potential of the Higgs field is given as: $$V_0 = -\frac{\mu^2}{2} \phi^2 + \frac{\lambda}{4} \phi^4 + ...
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What is the temperature dependence of the weak interaction which converts protons into neutrons in Big Bang Nucleosynthesis?
In section 4.2.1 of Dodelson's textbook "Modern Cosmology" (2nd edition, 2020), we consider the weak interaction $ p + e^{-} \to n + \nu_{e} $. In this section it claims, "as the ...
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What are particles (both fermions and bosons) composed of and explained as in Loop Quantum Gravity? [duplicate]
From my understanding of LQG, spacetime emerges from discrete quantum assumptions that come first, and I'm wondering how matter and energy particles are related to this (for example, string theory ...
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Two Questions on the Double Slit Experiment
Does the distance between the double slit wall, and the detector wall impact the interference pattern on the detector wall? Intuitively, I think the answer has to be yes, since in the extreme case, ...
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Why does the top quark decay via the weak interaction despite the weak coupling?
According to the wikipedia, top quarks decay exclusively via the weak interaction by emitting a W boson, which seems very strange because weak interaction is orders of magnitude weaker than EM and ...
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