Peskin schroeder Definition and 24 Threads

Michael Edward Peskin (born October 27, 1951, Philadelphia) is an American theoretical physicist. He was an undergraduate at Harvard University and obtained his Ph.D. in 1978 at Cornell University studying under Kenneth Wilson. He was a Junior Fellow at the Harvard Society of Fellows from 1977–1980.
He is currently a professor in the theory group at the SLAC National Accelerator Laboratory. Peskin was elected to the American Academy of Arts and Sciences in 2000.
Peskin is known for a widely used textbook on quantum field theory, written with Daniel Schroeder and published in 1995, and the Peskin–Takeuchi parameter. He has authored many popular review articles. He is a noted advocate of building a future linear collider.

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  1. DOTDO

    A Dirac Delta Function in Cross Section Formula (Peskin Schroeder QFT)

    In Peskin and Schroeder's QFT book, while deriving the cross section formula for particles ##A## and ##B##, a Dirac delta appears in Eq 4.77: \begin{align} \nonumber \int d\bar{k}^z_A \, \left. \delta ( F ( \bar{k}^z_A ) ) \right\vert_{\bar{k}^\perp_A = k^\perp_A, \, \bar{k}^\perp_B = k^\perp_B}...
  2. math-physicist

    A Interpreting the energy density of QFT vacuum states

    I am reading Peskin-Schroeder's QFT text, and there on pg. 98 Equation (4.56) they derive the expression for the vacuum energy density (relative to the zero of energy set by ##H_0|0\rangle = 0##): $$ \frac{E_0}{\rm{Volume}} = \frac{i\,\sum\text{(all disconnected pieces)}}{(2\pi)^4\,\delta^4(0)}\...
  3. D

    P&S Exercise 3.4 Majorana Fermions Derivative of ##\chi##

    I am stuck at the final part where one is supposed to show that the derivative of the second term of the action gives the mass term in the Majorana equation. For $$\chi^T\sigma^2\chi = -(\chi^\dagger\sigma^2\chi^*)^*$$ we get $$\frac{\delta}{\delta\chi^\dagger}(\chi^\dagger\sigma^2\chi^*)^*$$...
  4. Pouramat

    Weyl Spinors Transformation, QFT1, Peskin, Chapter 3

    \begin{align} \psi_L \rightarrow (1-i \vec{\theta} . \frac{{\vec\sigma}}{2} - \vec\beta . \frac{\vec\sigma}{2}) \psi_L \\ \psi_R \rightarrow (1-i \vec{\theta} . \frac{{\vec\sigma}}{2} + \vec\beta . \frac{\vec\sigma}{2}) \psi_R \end{align} I really cannot evaluate these from boost and rotation...
  5. N

    Calculation of g-factor correction in Peskin p. 196

    I'm reading peskin QFT textbook. In page 196 eq. (6.58) it says $$F_2(q^2=0)=\frac{\alpha}{2\pi}\int ^1_0 dx dy dz \delta (x+y+z-1) \frac{2m^2z(1-z)}{m^2(1-z)^2}\\=\frac{\alpha}{\pi}\int ^1_0 dz\int ^{1-z}_0 dy \frac{z}{1-z}=\frac{\alpha}{2\pi}$$ I confirmed the conversion from the first line...
  6. W

    I Propagator of a Scalar Field via Path Integrals

    I don't understand a step in the derivation of the propagator of a scalar field as presented in page 291 of Peskin and Schroeder. How do we go from: $$-\frac{\delta}{\delta J(x_1)} \frac{\delta}{\delta J(x_2)} \text{exp}[-\frac{1}{2} \int d^4 x \; d^4 y \; J(x) D_F (x-y) J(y)]|_{J=0}$$ To...
  7. W

    I Inner Product Between States of Multiple Particles

    $$<p_1 p_2|p_A p_B> = \sqrt{2E_1 2E_2 2E_A 2E_B}<0|a_1 a_2 a_{A}^{\dagger} a_{B}^{\dagger} |0>$$ $$=2E_A2E_B(2\pi)^6(\delta^{(3)}(p_A-p_1)\delta{(3)}(p_B-p_2) + \delta^{(3)}(p_A-p_2)\delta^{(3)}(p_B-p_1))$$ The identity above seemed easy, until I tried to prove it. I figured I could work this...
  8. W

    I Cross Section Formula in Peskin and Schroeder

    On page 105 of Peskin and Schroeder's book it says that the integral over ##d^2b## in the expression: $$d\sigma = \left(\Pi_f \frac{d^3 p_f}{(2\pi)^3}\frac{1}{2E_f}\right) \int d^2b\left(\Pi_{i=A,B} \int \frac{d^3 k_i}{(2\pi)^3}\frac{\phi_i(k_i)}{\sqrt{2E_i}} \int \frac{d^3...
  9. W

    A Questions from Peskin & Schroeder 5.5 about Compton Scattering

    Hi! Just a couple questions on the Compton scattering calculation in P&S. I feel like I'm missing something very simple here but can't quite figure out what it is. On page 166, the amplitude to be evaluated is $$ i\mathcal M = -ie^2 \epsilon_\mu(k)\epsilon^*_\nu(k^\prime) u_R^\dagger(p^\prime)...
  10. P

    A The Optical Theorem for Feynman Diagrams

    In Peskin's textbook section 7.3 The Optical Theorem for Feynman Diagrams(Page233), he said it is easy to check that the corresponding t- and u-channel diagrams have no branch cut singularities for s above threshold. But I can't figure out how to prove it. Can angone help me? Thanks!
  11. N

    Quantizing the complex Klein-Gordon field

    I'm self-studying QFT and attempting exercise 2.2 on Peskin & Schroeder. First off, I'm a bit confused on the logic the authors use in the quantization process. They first expand the fields in terms of these ##a_{\vec{p}},a_{\vec{p}}^\dagger## operators which, if I understand correctly, is...
  12. P

    A Confusion about the Z factor(Renormalization factor)

    In Peskin's textbook chapter 7 Radiative Corrections: Some formal developments (page 229), he said the Z factors are irrelevant for calculations at the leading order of perturbation theory, but are important in the calculation or higher-order corrections. My question is how can the Z factor be...
  13. S

    I How to Calculate Page 14 of Peskin Schroeder without Getting Stuck?

    Hi Everybody, I am trying to do the calculation of Peskin Schroeder page 14, namely the first block of equations. The author moves from: U(t) = \frac{1}{2 \pi^3} \int d^3p e^{-i(p^2/2m)t} e^{ip \cdot (x-x_0)}. to U(t) = (\frac{m}{2 \pi i t})^{3/2} e^{im(x-x_0)^2/2t}. I guess the way to go...
  14. hilbert2

    A Scalar Fields with the Same Mass

    In the Peskin&Schröder's QFT book there's an exercise that's about a pair of scalar fields, ##\phi_1## and ##\phi_2##, having the field equations ##\left(\partial^{\mu}\partial_{\mu}+m^2 \right)\phi_1 = 0## ##\left(\partial^{\mu}\partial_{\mu}+m^2 \right)\phi_2 = 0## where the mass parameter...
  15. S

    Quantum Particles & Quantum Fields - Hagen Kleinert

    I've discovered a potential treasure horde tucked away in the deep dark folds of the world wide web. A 1625 page mammoth on all aspects of quantum field theory by Prof. Hagen Kleinert. There's a draft ed. for free available here -...
  16. N

    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...
  17. S

    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...
  18. P

    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...
  19. I

    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...
  20. N

    Peskin Schroeder which chapter

    Hi, May you please asdvise me where in Peskin Schroeder it is described how to derive 1/r potential for electrodynamics... (I mean from quantum field point of view) Thanks
  21. P

    Peskin Schroeder Problem 5.6 (b) Weyl spinors

    Hey! I have a problem with problem 5.6 (b) from Peskin + Schroeder. Maybe I just don't see how it works, but I hope somebody can help me! Homework Statement We are asked to calculate the amplitude for the annihilation of a positron electron pair into two photons in the high-energy limit. The...
  22. S

    Peskin Schroeder: How to Derive Sin^2 Using Compton Relation?

    Dear PF, I have one question form Peskin Schroeder...could you pls help me It is very simple question... Since I don't know how to write formulas here I put my question in attachment. Thank you very much.
  23. S

    Question form Peskin Schroeder

    Sorry for bothering... How does righthand side of formula 5.94 is derived from its left handside after some approximation? Probably it is very simple question but I could't get that expression:confused: Thank u very much
  24. N

    How Does Causality Emerge in Quantum Field Theory Expressions?

    Gentlemen, Could you help me please, I am sure it is not even worthy of your attention, but anyway... In Peskin, Schroeder - from expresion <0|\phi(x)\phi(y)|0> survives <0|a_p a_q^\dag|0> so it creates one-particle state |q> at position y and another one-particle state | p> at postion...
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