Recent content by WarDieS

  1. W

    How can x=tan(x)cosh2(x) be solved using trigonometry?

    As already said, that's an approximation since you are not using the whole series. A more precise result using Mathematica is 2.1773189849653067526. By the way, I made a typo, I meant \frac{1}{2}\sinh(2x) which solution is x=0
  2. W

    Differential cross-section for partonic collisions

    Thanks RGevo, I am aware that I have to take with care the polarization states, ghost term and so on, that's why i am asking for an example, doing this is tricky for me. I will take a look at those chapters you talk about. Thanks again
  3. W

    Differential cross-section for partonic collisions

    I am sorry there is a typo, the second one is q + \bar{q} \rightarrow g + g . Thanks for the paper, I will look it into detail, Its not what i had in mind but it appears it has some comments about how calculating.
  4. W

    Differential cross-section for partonic collisions

    Thanks for your response. I just want to calculate them. The Peskin and Schroeder book proposes problems with the second and third examples I wrote. I am aware of some of the things you said, but still I want to calculate them, I am asking for a detailed calculation already done or at least a...
  5. W

    How can x=tan(x)cosh2(x) be solved using trigonometry?

    \tanh(x) goes from zero to one, \cosh^2(x) blows up to infinity, the only solution is x=0. Also, \tanh(x)\cosh^2(x) = \frac{1}{2}\sinh(x) and x = \frac{1}{2}\cosh(x) has no solution
  6. W

    Momentum is not conserved with elastic bouncing ball?

    Unless the door is moving against the ball, the ball won't bounce with more velocity. Momentum is always conserved
  7. W

    How can x=tan(x)cosh2(x) be solved using trigonometry?

    If you want the numbers for which the equation holds, I think you may want (and have) to do it by plotting, or using some numeric method. It has infinite solutions, the first one has be zero since you have \tan(0)=0, some solutions are x = 3.36922, 6.3062, 9.4263, 12.5665, 15.708
  8. W

    Differential cross-section for partonic collisions

    I am trying to calculate differential cross-section for partonic collisions (QCD) like q + q \rightarrow q +q q + \bar{q}\rightarrow q + q g + g \rightarrow g + g I can't find those calculations done anywhere, just the results and maybe some middle tips, that's all. As you may know those...
  9. W

    Conserved Charges of Stress Energy Tensor

    Yes you are right andrien, i can't believe i didnt notice it myself, many thanks!, i was just considering it as a number for not clear reasons, thanks again.
  10. W

    Conserved Charges of Stress Energy Tensor

    Hello, Hi There I am trying to obtain the relations of the conserved charges of the stress tensor, it has 4, one is the hamiltonian and the other three are the momentum components. \vec{P}=-\int d^3y \sum_i{(-\pi_i(y) \nabla \phi_i(y))} And i have to prove the conmutators...
  11. W

    Problem with normalization wave function position/momentum space

    Homework Statement We start with a pure state at t=0 of an electron is C e^{- a^2 x^2} \left(\begin{array}{c} 1\\ i \end{array}\right) Probability density of measuring momentun p_0 and third component of spin - \frac{\hbar}{2} And probability of measuring a state with momentum...
  12. W

    Quantum Harmonic oscillator, <T>/<V> ratio

    Seems to me you forgot a minus sing in ## \langle T \rangle ##
  13. W

    Particle with spin 1 in a non perturtuvative interaction

    i am really grateful, thanks for your patience with me :D
  14. W

    How do you calculate the energy delivered by a capacitor

    You wrote ## \frac{1}{2}C V^2 ## without an equal sign, check in your notes what's that equal to. That equation relates C, V with something that may be interesting for you
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