ndrearu
  • Member for 3 years, 11 months
  • Last seen more than 3 years ago
Literature on lattice quantum field theory
6 votes

There are many textbooks or reviews representing a good introduction to Lattice QFTs. Here I list some of them I found very useful in my studies (sure I'm missing something). Lattice Gauge Theories ...

View answer
What will be the trajectory of the given motion
Accepted answer
5 votes

Ok let's try. I think that there are a lot of way to do so and I will try one (maybe not the faster way, but should be clean enough). To understand the motion we need just two dimensions, so we work ...

View answer
Confusing Question on "Degrees of Freedom"
3 votes

The mistake is just here If we use θ, ϕ and ξ to describe the position of P, it means P has three degree of freedom. The number of degrees of freedom is not the number of variables you use to ...

View answer
Monte Carlo steps in Ising model Metropolis algorithm
2 votes

Generally speaking, in a Markov Chain Monte-Carlo (MCMC) the therm step may be used to indicate any move from a state (or configuration) in the chain to the next one. Clearly, this step (or update, ...

View answer
Is dimensional analysis wrong?
2 votes

Obviously is not the dimensional analysis to be wrong. It is wrong if one tries to rely only on it to find physical laws, despite it clearly represents a very good help to us. In the example of the ...

View answer
Partition Function- Are the energies of the individual microstates, free energies?
2 votes

No, the $E_i$s are energies. In statistical mechanics it can be show (see for example here) that the Helmotz's free energy $F$ is related to the partition function of the system in the following way $$...

View answer
Two different definition of quantum Poisson bracket, which one to use?
2 votes

Yep, it is actually just a matter of convention. I don't think that choosing the first or the second one would change nothing but the convenience in the computations. As far as I know, the second ...

View answer
Compression of gases
2 votes

Be careful. Heat refers to the transfer of energy between thermodynamical systems, and so it is not properly correct to say that a system has heat. A system has energy which can be transferred in form ...

View answer
Is the efficiency of a reversible heat engine independent of the processes involved?
Accepted answer
2 votes

The Carnot theorem states the maximum efficiency of an heat engine is that of the Carnot heat engine and this depends only on the temperatures of the two heat reservoirs. In addition to that, there is ...

View answer
Thermodynamic equilibrium, mixing gases of two different temperatures
1 votes

I would try to go through the questions: The definition of thermal equilibrium is quite more general. According to K. Huang (K. Huang, Statistical Mechanics) Thermodynamic equilibrium prevails ...

View answer
Heat capacity increases with temperature
Accepted answer
1 votes

I think that a possible and very simple argument may be just the following. The heat capacity is the quantity of heat needed to vary the temperature of a certain amount. If it grows with the ...

View answer
Calculating the probability of transmission of a wave function between two delta distributions
1 votes

Ok your ansatz about the form of the $\psi$. Now, the other conditions you need come from the discontinuity of the derivative through the delta potential. If you take the time-independent Schrödinger ...

View answer
Projectile motion explanation
1 votes

A way to answer is just to write down the equation of motion and let you see that mass is not involved. However, I think that your question may lie on a more deep level. It seems stupid but, perhaps, ...

View answer
Minimal substitution, four-potential and units
1 votes

You're just missing that there is something proportional to $e$ also in the four-potential $A_\mu$ since $A_\mu=(\phi,\vec{A})$ where $\phi$ and $\vec{A}$ are the scalar and vector potentials. The ...

View answer
Why $c$ needs to be added in numerator and denominator while solving a de Broglie equation word problem?
1 votes

It is not necessary to add $c$, it is just useful in order to check quickly the dimensions, easily recognize quantities and get the numerical value of the formula faster. This is done often in Physics ...

View answer
Critical angle equations - air and not air
1 votes

It should be just a problem of definitions of the mediums and their refractive indices. In the general case, when you have two mediums separated by a boundary and with refractive indices $n_1$ and $...

View answer
Magnet and its orientation
Accepted answer
1 votes

Magnets tends to align to the field lines of a magnetic field. Earth possesses a magnetic field whose axis does not coincide with the rotation one but differs of about 11° (see here), so in ideal ...

View answer
Electron-positron pair production requiring a nucleus
1 votes

A way to show that a single photon cannot decay into a massive particle-antiparticle pair can be wrote down by using the four-vector formalism. The decay is $$ k^\alpha=p_1^\alpha+p_2^\alpha $$ where $...

View answer
Relationship between the partition function and the Hamiltonian
0 votes

The second formula must be handle with care. It is possible to show that the thermodynamic partition function of a system described by an Hamiltonian $H$ may correspond to the path integral under some ...

View answer
Mass-Energy equivalence in case of minimal coupling
0 votes

Yes, indeed it is the expression of the energy of a relativistic massive charged particle in the presence of an electric potential. Consistently, if the expression is expanded in the limit $cp\ll mc^2$...

View answer
Integration of Acceleration to Get Delta Velocity
0 votes

If I understand correctly, you want to find $\delta v=v(t_2)-v(t_1)$, the difference between the velocities of a point at some instants $t_2>t_1$, knowing the value of the accelerations $a(t_2)$ ...

View answer
Splitting velocity into linear and tangential velocity
Accepted answer
0 votes

You're right when you say that [...] velocity will be partially due to linear motion of the whole system, and partially due to rotation of A around B. indeed, the velocity of $A$ is the sum of two ...

View answer
Lorentz Covariance of the law $\mathbf{\vec{F}} = \frac{d\mathbf{\vec{p}}}{dt}$
0 votes

Here a little trick: if you write $$ \mathbf{F}' = \frac{d\mathbf{p'}}{dt'} = \frac{d\mathbf{p'}}{dt}{\Big/}\frac{dt'}{dt} $$ then $$ F'_x=\frac{dp_x'}{dt}{\Big/}\frac{dt'}{dt}\quad F'_x=\frac{dp_y}{...

View answer
Galilean Transformation
Accepted answer
0 votes

The argument is that in Galilean transformation you assume time to be absolute. Translating this requirement in an operative statement, you want intervals of time between to events to be invariant ...

View answer
Understanding period of a sine wave in physics
0 votes

If I understand correctly the answer, it is just a matter of understanding who-is-who. Stating that a function is periodic with period $2\pi$ means that if its argument is shifted by $2\pi$, than the ...

View answer
What's the meaning of $\alpha$ in this derivation?
Accepted answer
0 votes

I think it is just the name the generic quantum state you're considering to construct the Path Integral representation. Then, in the subsequent lines it is thrown away by inserting a sum over the ...

View answer