# What is Schroeder: Definition and 71 Discussions

Schroeder is a North German (from Schröder) occupational name for a cloth cutter or tailor, from an agent derivative of Middle Low German schroden, schraden "to cut". The same term was occasionally used to denote a gristmiller as well as a shoemaker, whose work included cutting leather, and also a drayman, one who delivered beer and wine in bulk to customers; in some instances the surname may have been acquired in either of these senses. This name is widespread throughout central and eastern Europe which has been held by many notable people, including:

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1. ### Medical Student who misses physics

G'day from Australia! I loved physics and maths in high school and I have been trying to teach myself some physics on the side whilst doing another course at university. So far, I have read and done problems from "Introduction to Thermal Physics (Schroeder)" [I got up to around 7.4] and...

18. ### Differentiation of unitary operator U(t,t') in Peskin and Schroeder

How the authors came to the conclusion (eq. 4.25) that $$U(t,t')=e^{iH_0(t-t_0)} e^{-iH(t-t')} e^{-iH_0(t'-t_0)}$$
19. ### Peskin and Schroeder eq. 18.84

Homework Statement So I am self-studying the book of Peskin&Schroeder, and there is something I don't understand on page 616. In eq. 18.80, there is a numerical factor of ½ and going from e2 to α will introduce a factor 4π when proceeding to eq. 18.84. But then there should be a numerical...
20. ### Peskin & Schroeder - page 5 - Computation of ##\mathcal{M}##

The following is taken from page 5 of Peskin and Schroeder. It talks about the computation of ##\mathcal{M}## for the annihilation reaction ##e^{+}e^{-}\rightarrow \mu^{+}\mu^{-}##. Even for this simplest of QED processes, the exact expression for ##\mathcal{M}## is not known. Actually this...
21. ### Peskin and Schroeder - page 4 - spin and cross section

In chapter 1 of Peskin and Schroeder, the reaction ##e^{+}e^{-}\rightarrow \mu^{+}\mu^{-}## is studied in detail. The related following paragraph is taken from page 4 of Peskin and Schroeder: Both the electron and the muon have spin ##1/2##, so their spin orientations must be specified. It is...
22. ### Peskin and Schroeder - page 4 - choice of notation

In page 4, Peskin and Schroeder has the following diagram: The diagram shows the collision of an electron beam and a positron beam to produce a ##\mu^{+}## beam a ##\mu^{-}## beam. My question is this: The electron and positron beams are shown to have momenta ##\textbf{p}## and...
23. ### Peskin and Schroeder page 38

In page 39, Peskin and Schroeder write that (3.15) ##{\bf{J}}={\bf{x}} \times{\bf{p}}= {\bf{x}}\times(-i \nabla) ## can be used to derive the Lorentz algebra (3.12) for the rotation group: ##[J^{i},J^{j}] = i \epsilon^{ijk}J^{k}##. I am trying to prove it. Here's my attempt. Can you please...
24. ### Peskin and Schroeder - Derivation of equation (2.45)

I'm having trouble deriving equation (2.45) on page 25. In particular, in the derivation of ##i\frac{\partial}{\partial t}\pi({\bf{x}},t) = -i(-\nabla^{2}+m^{2}) \phi({\bf{x}},t)##, I need to show that ##\frac{1}{2}\pi({\bf{x}},t) \phi({\bf{x'}},t)(-\nabla^{2}+m^{2}) \phi({\bf{x'}},t) -...
25. ### S matrix Unitarity Proof, pg 298 Peskin Schroeder

I have a question regarding a derivation in Peskin and Schroeder's QFT book. On page 298, he is discussing a method for defining a gauge invariant S matrix. He does this by defining projection operators ##P_0## that project general particle states into gauge invariant states, and then defining...
26. ### Contour Integral from Peskin & Schroeder Intro to QFT

1. I'm having some trouble with some of the contour integrals covered in Chapter 2 of Peskin & Schroeder's Intro to QTF. I'm not so much as looking for answers to the integral (in fact, the answers are given in the textbook), but I was hoping someone could point me to some resources to use to...
27. ### Questions from Peskin and Schroeder

On page 42 of Peskin, at the bottom they say that the next transformation should follow: ##[i\gamma^\mu\partial_\mu - m ]\psi (x) \rightarrow [i\gamma^\mu(\Lambda^{-1})^\nu_\mu \partial_\nu - m ] \Lambda_{1/2} \psi (\Lambda^{-1}x)## But why does the factor ##\Lambda_{1/2}## appear there...
28. ### Schroeder: Intro to thermal physics, Diff. between editions?

Hi, I'm facing a slight problem with getting a good version of the Schroeder: Introduction to thermal physics. According to my lecturer the newest 2013 international edition by Pearson (ISBN: 9781292026213) is not recommended, as it lacks some aspects. And anyway the course is built around the...
29. ### Question on peskin and schroeder

If you go to page 20 and 21 where the Fourier expansion of the klein-gordon field operator is derived, you'll see equation (2.27). Now there are some small details of this whole calculation that I'm confused about. I followed all the way through to (2.25), but here I feel a bit weird. Isn't he...
30. ### Peskin & Schroeder Problem 4.1

I am having some problems in evaluating the current problem's question (b)... I have reached the point (writing only the term which I have problem with): A_{3}= - \frac{1}{2} \int_{t_{0}}^{t} dt' dt'' \int d^{3}x \int d^{3}y j(x,t') j(y,t'') D_{F}(x-y) So for some unknown reasons, I cannot...
31. ### Peskin and Schroeder derivation of Klein-Gordon propagator

In page 30 of book "An introduction to quantum field theory" by Peskin and Schroeder in the derivation of Klein-Gordon propagator, why p^0=-E_p in the second step in equation (2.54). and why change "ip(x-y)" to "-ip(x-y)"? I thought a lot time, but get no idea. Thank you for your giving me an...
32. ### How accessible is the Peskin and Schroeder textbook?

**Please can an administrator move this to the "Maths and Physics Learning Materials" section- I can't post there for some reason. Thank you!** Hello, I am interested in learning some more technical Quantum Mechanics, and was wondering how accessible the Peskin and Schroeder textbook is as...
33. ### (Peskin and Schroeder) Numerator of vertex correction

Hi I am studying qft with worldwidely used text, written by Peskin and Schroeder, An introduction to qft. I have trouble with the calculation of thr numerator on pp. 192. I got additional term ## 2m(z-xy)(mγ^μ - p^μ) ## between spinors, which seems not vanishing. Is there any idea to treat this...
34. ### Peskin Schroeder page 30 eq 2.54

Hello Everybody, I am trying to get the second line of 2.54 from the last line; I want to get: \int \frac{d^3p}{{2 \pi}^3} \{ \frac{1}{2 E_\vec{p}} e^{-ip \cdot (x-y) }|_{p^0 = E_\vec{p}} + \frac{1}{-2 E_\vec{p}} e^{-ip \cdot (x-y) }|_{p^0 = -E_\vec{p}} \}, from \int...
35. ### Polarization of photon-Peskin and Schroeder

Hi, I am currently studying quantum field theory with worldwidely used text written by Peskin and Schroeder. On page 165 of that text it says, " the amplitude vanishes unless the final photon is right-handed." But I cannot figure out how it works. With ε = (0,1,i,0), I get same expression...
36. ### Renormalization procedure (Peskin and Schroeder)

In Peskin and Schroeder at page 323 second paragraph the author state 'To obtain finite results for an amplitude involving divergent diagrams, we have so far used the following procedure: Compute the diagrams using a regulator to obtain an expression that depends on the bare mass (m0), the...
37. ### Fourier transform of integration measure (Peskin and Schroeder)

At page 285 in Peskin and Schroeder's Introduction to quantum field theory the author defines the integration measure D\phi = \Pi_i d\phi(x_i) where space-time is being discretised into a square lattice of volume L^4. He proceeds by Fourier-transforming \phi(k_n) = \frac{1}{V} \sum_n e^{-i...
38. ### Splitting up of functional integral (Peskin and Schroeder)

I'm reading about path integrals in Peskin and Schroeder's Introduction to Quantum field theory and there is a few things in the text which I find puzzling. At page 283 in the section about correlation functions we are considering the object (equation 9.15) \int D\phi(x) \phi(x_1) \phi(x_2)...
39. ### Peskin & Schroeder QFT Born Approximation reference.

I'm currently teaching myself some QFT trough Peskin and Schroeders Introduction to QFT and I've noticed that in several arguments they rely on appealing to the Born approximation of non-relativistic QM scattering theory. For example on page 121 equation (4.125) they appeal to the scattering...
40. ### Differential cross sections in Peskin & Schroeder

I'm a bit confused by something Peskin & Schroeder say about differential cross sections. In my printing, this is on page 101 in the paragraph preceding the one that contains eq. 4.62: "In the simplest case, where there are only two final-state particles, this leaves only two unconstrained...
41. ### Peskin & Schroeder p. 285, change of variables integration measure

I had a question about about the integration measure for the path integral after a unitary change of variables. First they consider a 4D spacetime lattice with volume L^4. The measure is \mathcal{D}\phi = \prod_i d\phi(x_i) They expand the field variables in a Fourier series...
42. ### Integration question in Peskin and Schroeder

Hi all, I'm stuck with proving the last step of (2.51) in Peskin and Schroeder: \begin{align} D(x-y) &= \frac{1}{4\pi^2}\int^\infty_m dE \sqrt{E^2 - m^2}e^{-iEt}\\ & \approx_{t \to \infty}\ \ e^{-imt}\end{align} I've read on another post that the solution is to use the method of...
43. ### Polarization vector in Peskin & Schroeder QFT

Hi all, A friend and I are working through Peskin and Schroeder, and we're both stumped with only the fourth equation! The interaction in question is e^+ + e^- \to \mu^+ + \mu^- with a virtual photon as the inner branch. P&S state that \mathcal{M}\propto \langle \mu^+\mu^- | H_I | \gamma...
44. ### Factor in equation (3.49) of Peskin and Schroeder

My question concerns the 1/2 factor in the exponential of Eq. (3.49) of Peskin and Schroeder. This equation concerns the Lorentz boost transformation of a spinor along the z-axis (or 3-direction). According to Eq. (3.26): S^{03} = -\frac{i}{2}\begin{bmatrix}\sigma^3 & 0 \\0 &...
45. ### Fick's Law (Schroeder, Thermal Physics Page 47)

This isn't a HW problem - I am just having a hard time following one of his examples. On page 47 near Eq. 1.71 he says "As a quick example, consider a drop of food coloring added to a glass of water. Imagine that the dye has already spread uniformly through half of the glass. How long would...
46. ### Pesking & Schroeder Eqn 3.18 (Lorentz algebra)

I am trying to show that (for 4x4 matrices) the representation given by equation 3.18 (Peskin and Schroeder, page 39): (J^{\mu\nu})_{\alpha\beta} =i(\delta^{\mu}_{\alpha}\delta^{\nu}_{\beta}-\delta^{\mu}_{\beta}\delta^{\nu}_{\alpha}) implies the commutation relations in 3.17...
47. ### Another doubt in Peskin Schroeder Sec 4.2

This doubt is about a text in Peskin Schroeder Pg 86. I reproduce it here. -------------------------------- U(t,t') satisfies the same differential equation (4.18), i \frac{\partial}{\partial t} U(t,t') = H_I(t) U(t,t') but now with the initial condition U=1 for t=t'. From this...
48. ### Peskin Schroeder Enigmatic Equation

Hi, I am learning QFT in the Peskin/Schroeder book and I found 4.56 on page 98 really weird, it is: \rho_{vaccum\: energy\: density} = \frac{i\sum_{all\: disconnected\: diagramms}amplitude}{(2\pi)^4\delta^{(4)}(0)} The authors do not comment really this result, but could someone tell me at...
49. ### How Do You Quantize Spinor Theory in Quantum Field Theory?

Homework Statement Problem 3.4e of Peskin & Schroeder Introduction to Quantum Field Theory. Quantize the spinor theory of item (a) of this exercise, where the spinor \chi is the first two components of the Dirac spinor (\psi_L). Find a Hermitean Hamiltonian and the correct...
50. ### QED: Vertex renormalisation; Please have Peskin and Schroeder book handy

Hi guys, I have a question regarding a point in the QFT book of peskin and schroeder. Iv been working through renormalisation in QED, The 2-point corrections are simple enough, however in this book the 3-point function is a little more involved and I have some issues. Essentially id to...