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2
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3answers
96 views

Simple real-life examples of Fermi's golden rule?

I want to teach my students some simple applications of Fermi's Golden Rule. Unfortunately, most examples I can think of are in scattering theory, which they have not learned yet. Are there any ...
0
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0answers
34 views

Can the half-life of rubidium 87 be theoretically estimated?

Can the Fermi golden rule be applied to give an approximation of this half-life?
1
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0answers
72 views

Why doesn't Graphene have a band gap?

Is there any simple justification about graphene having no band gap? How bout its linear E-K? Why bilayer graphene has a quadratic E-K and electric field can open a band gap there? I do not ...
0
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0answers
78 views

When is Fermi golden rule exact?

My recent study Nonsmooth and level-resolved dynamics illustrated with a periodically driven tight binding model motivates me to ask this question: Is there any example in which the Fermi golden rule ...
5
votes
1answer
121 views

Why doesn't Fermi's golden rule distinguish attraction from repulsion?

Let's say I have two distinguishable charged particles interacting electrostatically. In Fermi's golden rule, the two particles can change state at a rate proportional to: $$|\langle \psi_f | H_{int} ...
0
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0answers
38 views

Physical interpretation of Fermi golden rule? [duplicate]

What is the physical interpretation of Fermi's golden rule?
2
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0answers
53 views

What is the physical meaning of the “decay rate” in Fermis golden rule? [duplicate]

As far as I understood, Fermi's golden rule gives a prediction of the transition rate in a perturbed quantum system $H_0+V$ between two eigenstates of the unperturbed system $H_0$, say from $\left| ...
3
votes
0answers
87 views

Delta normalization and density of states in the Golden rule of Fermi

In the text-book derivation of first order inelastic scattering amplitude, box normalization is usually used to calculate the result. This leads to a correct result through the Golden Rule of Fermi, ...
11
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3answers
2k views

Interpretation of “transition rate” in Fermi's golden rule

This is a question I asked myself a couple of years back, and which a student recently reminded me of. My off-the-cuff answer is wrong, and whilst I can make some hand-waving responses I'd like a ...
2
votes
1answer
123 views

Why multiply by volume when integrating over final momenta in scattering amplitude calculations?

I am learning about calculating decay rates from quantum field theory amplitudes from David Tong's lecture notes (page 74 in the notes, 24 in document). However, I have some doubts: When he says the ...
1
vote
1answer
294 views

Fermi's golden rule and Probabilities in QM

In Fermi's golden rule $$P_{ab}(t)=2\pi t/\hbar \left|\langle\psi_b|V|\psi_a\rangle\right|^2 \delta(E_f-E_i)$$ for transition probability from state $a$ to $b$, how can the probability grow with ...
1
vote
1answer
261 views

Density of States for Fermi's Golden Rule

I recently read a question on fermi's golden rule posted here: Fermi's Golden Rule and Density of States However, I do not really know how you would go about obtaining a value for the density of ...
2
votes
3answers
1k views

Fermi's Golden Rule and Density of States

I know Fermi's Golden Rule in the form $$\Gamma_{fi} ~=~ \sum_{f}\frac{2\pi}{\hbar}\delta (E_f - E_i)|M_{fi}|^2$$ where $\Gamma_{fi}$ is the probability transition rate, $M_{fi}$ are the transition ...
4
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3answers
254 views

Irreversibility and the Fermi golden rule

When a quantum system is perturbatively coupled to a continuum of states, one uses the Fermi's golden rule to compute the rate of transition form an initial state to a set of states contained in an ...
11
votes
1answer
945 views

Cross-section in relativistic limit: Fermi's golden rule still valid?

In order to calculate the cross-section of an interaction process the following formula is often used for first approximations: $$ \sigma = \frac {2\pi} {\hbar\,v_i} \left| ...
9
votes
1answer
464 views

Universality in Weak Interactions

I'm currently preparing for an examination of course in introductory (experimental) particle physics. One topic that we covered and that I'm currently revising is the universality in weak ...
4
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1answer
799 views

Fermi's Golden Rule

It is well known that to calculate the probability of transition in the scattering processes, as a first approximation, we use the Fermi golden rule. This rule is obtained considering the initial ...