All Questions
22
questions
1
vote
0
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36
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Does the changes of flow regimes of the renormalization group flow diagram imply always that a symmetry has been broken?
Usually we can use RG flow diagrams to understand that a phase transition has happened. Because they are intimately related to a broken symmetry, does that imply that it always implies that a symmetry ...
- 11
3
votes
1
answer
83
views
Is RG fixed point always related to a second-order phase transition?
In practice, usually one of the parameters is tuned (for example temperature in 3D Ising model, which is a relevant parameter) so that it coincides with the value of RG fixed point, then RG flow make ...
- 619
8
votes
3
answers
448
views
Relation between Spontaneous Symmetry Breaking and Renormalization Group
I have two different pictures in my head of how a phase transition occurs, but I am not sure of the relation between these two pictures.
SSB: Our theory has a global symmetry and when the parameters ...
- 642
4
votes
0
answers
514
views
Connection Between Renormalization Group and Phase Transitions
I have a couple of questions on the relation of RG and phase transitions. I've heard in many sources that the theory of most transitions (excluding novel phase transitions like Quantum Critical ...
- 642
1
vote
0
answers
70
views
Fluctuation-Dissipation Relation for Quantum Phase Transitions
I am looking for a formulation for the fluctuation-dissipation relation connecting the correlation related quantities with the thermodynamic functions at the quantum critical point.
The fluctuation-...
- 646
3
votes
0
answers
275
views
Correlation length and renormalization group
In Scaling and Renormalization in Statistical Physics there's following block of information:
I have some misunderstanding of some ideas.
1) How to define correlation length for arbitrary theory?
I ...
- 5,707
0
votes
2
answers
130
views
What is possible to extract from Landau-Ginsburg theory?
Landau-Ginsburg theory efficiently describe physics in vicinity of critical point and predict approximate critical exponents in 3d through $4-\varepsilon$ expansion.
But as I understand, in ...
- 5,707
3
votes
0
answers
169
views
Phase diagram of ${\rm O}(3)$ lattice model and mean field theory
In David Tong: Lectures on Statistical Field Theory Problem Sheet 1 exist task:
I fully understand this problem and I know solution: section 17.2.
I am interested in application of mean field theory ...
- 5,707
2
votes
0
answers
139
views
Topological soliton objects in Minkowski v.s. Euclidean spacetime?
What makes the distinctions between the soliton objects in Minkowski or in Euclidean spacetime?
It looks that usually, the Euclidean path integral is easier to be performed in many cases. In fact, ...
- 7,848
14
votes
1
answer
1k
views
Why are symmetric quantum ground states cat states iff the ground-state manifold is degenerate?
The usual story of symmetry-breaking quantum phase transitions (I won't consider topological transitions here) goes like this: you have a Hamiltonian $H(g)$ describing an infinite system which depends ...
- 48.4k
10
votes
1
answer
996
views
Why does Josephson's identity $d\nu=2-\alpha$ only hold for mean field theory in dimension $4$?
For phase transition, when approaching the critical point, the heat capacity $C \propto \tau^{-\alpha}$ and correlation length $\xi\propto \tau^{-\nu}$, with $\tau := \frac{T-T_\mathrm{c}}{T_\mathrm{c}...
- 2,147
8
votes
2
answers
732
views
What's about the critical exponents and RG flow in upper critical dimension $D=4$?
We know when $D>4$, i.e. $D$ larger than upper critical dimension, then critical exponents are exactly same as the ones of mean field . When $D<4$, critical exponents are not given correctly by ...
user153663
6
votes
0
answers
397
views
Renormalization, Phase transitions and order parameters
Renormalization is the phenomenon for which, once a finite number of parameters, which are the couplings with positive-mass dimension, are fixed, then it is possible to express any $n$-point ...
- 2,060
3
votes
1
answer
625
views
Why do we rescale and renormalize fields?
The Renormalization procedure is generically broken down into three steps (see eg Kardar Statistical Fields Chapter 4)
1) Coarse Grain (Typically this amounts to integrating out the fast Fourier ...
- 2,270
6
votes
2
answers
3k
views
Bose-Einstein condensation and phase transition
I would like to ask the following question for which I cannot find a definite answer in the literature.
Of what ORDER is the phase transition leading to Bose-Einstein condensation for a ideal and ...
- 1,323