Rules Definition and 539 Threads

I'm probably missing something small but I haven't been able to figure this out. In the Feynman rules (for a scalar field that obeys the Klein-Gordon equation), you write a propagator for internal lines as \frac{i}{k^2 - m^2 + i \epsilon}. The propagator integrand is originally...

I am new here to say all of you "hi!". Hope to be welcomed by all of you. I would like to be the part of the discussion going in this forum. And I think that you are enjoying a lot on this site. I am here for too which will enjoy soon. I am new here and I hope you will guide me to follow the...

Homework Statement give a general rule for when Integral (1/x^n) from (x, 0, a), a>0 converges or diverges. Homework Equations The Attempt at a Solution I have checked the textbooks for this answer but i can't seem to find it. The closest i got was Integral (1/x^n) from (x, 1...

I have been studying how to apply the Feynman rules for QED to various simple first order process (as prescribed by Griffiths' 'Introduction to Elementary Particles'). So far, all is well. I can follow the rules, and develop the results, and it all looks very clever. My problem is that so...

hey, I was asking myself a few questions about the selection rules for EM dipole radiation which occurs if electrons "jump" into lower bound states according to the selection rules. now I know that the full explanation about matrix elements of the dipole operator comes from fermi's golden...

Hi What rule or theorem of limits says that you can do this with a limit lim(h->0) (a+b)/h = lim(h->0) a/h + lim(h->0) b/h The book i am reading has just done something like that to a limit without saying why you can do that thanks

I have searched topics like reflection forum and I always seem to get different answers. I'm hoping to reconcile all of this, I've read FAQs, threads, wikipedia... To explain reflection I've heard these 3 explanations: 1) Light is absorbed by an atom, then re-emitted at a later time randomly...

Homework Statement Find limit lim x->0+ of lnx+1/x Homework Equations 1/x = ln e^1/x The Attempt at a Solution ln x + ln e^1/x = ln x*e^(1/x) lim x-> 0+ ln x + ln e^1/x = ln 0*inf = ln 0 = - inf lim x-> 0+ Source: my self vs http://www.numberempire.com/limitcalculator.php

Can anyone brief of on the different rules for doing ray tracing for both concave and convex lenses, as well as both concave and convex mirrors?? I understand the concepts but i can't seem to keep ray tracing in my head from the way our textbook explains it...

I know I should know this, but I have a quick question. Let's say we have a diagram: 1-->----------2 | | <- "q" v | 3--<----------4 Lets assume: 1 = "quark" 3 = "antiquark" 2 = W boson 4 = photon q = same quark flavor as "3" Time...

I am having trouble showing: <4 3 0 | p_z^2 | 4 0 0 > = 0 and <4 2 1 | x p_y | 3 1 0 > = 0 I know the usual selection rules for parity, spherical tensors (Wigner-Eckart for x,y,z) but I can't convert these two to anything I know. You could also help by telling me how to convert these to...

I always get slightly confused with the rules of differentials. now \frac{d^{2}y}{dx^{2}} is the scond derivative of the function y(x but rooting this does NOT give the first derivative dy/dx However, with the operator \frac{d^{2}}{dx^{2}}, it seems that you can root this and it DOES...

http://img17.imageshack.us/img17/201/73448266.jpg let's suppose that we know all resistors and voltages by applying kirchhof rules we have V1 - i*R1 - i*R2 -i2*R3 = 0 V1 - i*R1 - i*R2 - i1*R4 - V2 = 0 -V2 + i2*R3 - i1*R4 = 0 we know V1,V2,V3 R1,R2,R3 and we can find the currents...

Hello all. I feel like such a retard, but there's an example problem in my book with the answer, and I just don't know how they are getting the answer. I suppose it's due to my lack of mathematical skills. I was wondering if someone could guide me on how they got the answer...

Homework Statement http://img25.imageshack.us/i/circuitj.jpg (Image won't show up, here's the link http://img25.imageshack.us/i/circuitj.jpg/) Homework Equations Kirchoff's Junction & Potential rules. The Attempt at a Solution http://img29.imageshack.us/i/circuit2.jpg (Image won't show up...

Homework Statement So i had to do an experiment which consisted of measuring the current and voltage across different resistors. Here's my question: i recorded the current through the wire that passes through the resistor and compared it with the current which i calculated (theoretical). In...

Homework Statement Using a circuit similar to the circuit of the figure, but with the 55.0-V and 57.0-V sources replaced by a short circuit, determine the currents in each resistance. here is the diagram: http://session.masteringphysics.com/problemAsset/1054847/7/YF-26-89.jpg Find...

Hi, there exist tables with group theory breaking patters and branching rules such as E_7 \rightarrow E_6 \times U(1) 133 \rightarrow 78 + 1 + 27 + \bar{27} 56 \rightarrow 1 + 1 + 27 + \bar{27} What is missing is the U(1) charge. Does anyone know how to obtain it? Perhaps it could be...

Hi, Could u advise me please some references where the Feynman rules for graviton are derived I mean graviton-scalar graviton-graviton scattering ... in general graviton vertecies ... Thank you

I'd like to know if Kirchhoff's laws of voltage and current are valid in circuit with alternate current. If I'm not wrong, in such circuits, the E field provided by the emf is varying with time. And I've heard that Kirchhoff's laws are a special case of Faraday's law of induction but with a...

String theory requires 9 spatial dimensions, M-theory 10. One followup to Verlinde's paper is this: http://arxiv.org/abs/1002.0488 Hidden symmetries for thermodynamics and emergence of relativity Liu Zhao (Submitted on 2 Feb 2010) Verlinde recently proposed an idea about the thermodynamic...

Find currents , , and given the following values of resistances in the circuit: = 2.00 , = 3.00 , = 1.00 , = 4.00 , and = 10.0 . Enter your answers in amperes, separated by commas.

How does one deal with a delta squared ? For example, volume is a function of del Diameter and del Length. If i let v = d^2(pi)L/4, and then call the d and L del. d and del L, when i separate for d i get del d^2 So I'm wondering if there are any special rules for squaring a "del"

Homework Statement Calculate ground state of erbium [Xe] 4f^12 6s^2 The Attempt at a Solution so i know that the f orbital can hold 14 electrons and has 7 types of orbitals that is -3,-2,-1,0,1,2,3 So i constructed a table with axes of m_l (-3 to +3 above) and m_s. Then hunds rules...

True or False, with a proof or counterexample. a) If bn ≠ 0 and an/bn →1, then an-bn → 0 b) If bn ≠ 0, bn is bounded and an/bn → 1 then an-bn → 0 At the moment I cannot even see which is false so I am struggling with this question. I think the proof will require use of the quotient...

http://img51.imageshack.us/img51/659/car.gif Not intended as a political statement.

Homework Statement Find the average value of the function f(t) = (t-3)^2 on [0,6] Homework Equations Average value equation (see below) The Attempt at a Solution Okay, I have this: http://img4.imageshack.us/img4/5338/howthecrap.png But I don't know how it gets to the last...

Homework Statement Sorry for edit, accidentally posted. Circuit is show in my attachment. I have 3 loops with three unknown currents. 8 Ohms of resistance down the left side. 6 Ohms of resistance and a 4V battery down the center. 4 Ohms of resistance and a 12V battery down the right side. I...

The transition in the n=2 state of Helium from 3P1 (m=0) to 3S1 (m=0) is forbidden. I know this, because I went to a lecture where a group measured the fine structure constant very precisely using this fact. However, as far as I can see, according to atomic selection rules (available here...

Today I wrote a chemistry mid term examination. I was nearly finished when I heard "OK, times up, bring your test to the front", too bad i didn't finish I thought. On my way to the front I noticed people still writing the exam. I thought well that's unfair, but hey that's life. After I handed my...

Hello I sometimes have difficulty determining weather a problem is solvable or have trouble gauging the difficulty of a certain approach. I think this is because of a weak background in maths Say you had a general 2d single rigid body problem Which has 2 given forces and 3 unknowns...

I am reading some online article on Zeeman effect http://math.ucr.edu/home/baez/spin/node10.html In the article, the author mentions 4 selection rules, I wonder the corresponding transition is allowed by satisfying one of these selection rules or the corresponding line will be allowed only...

Homework Statement Hello all, thanks for reading... I was assigned to calculate feynman rules for the scalar QED theory via functional methods. The fields are a scalar complex field \phi, \phi^* and gauge field A_\mu, and the lagrangean is \mathfrak{L} = (D_\mu \phi)^* (D^\mu \phi) - m^2...

I have these two circuits with permanent rule: a) b) I'm asked to find: For a): the charges of each capacitor (C = 1 \muF)and the currents in each resistance. For b): the currents in each branch with the L switch on and off, the difference of potential between A and C, A and B and C...

Use the cosine and sine rules to determine the magnitude and direction of the resultant of a force of 11 kN acting at an angle of 50 degrees to the horizontal and a force of 6 kN acting at an angle of -30 degrees to the horizontal. helppp please

1. Suppose the curve f(x)=(x^4)+a(x^3)+b(x^2)+cx+d has tangent line when x=0 with equation y=2x+1, and a tangent line when x=1 with equation y=2-3x. Find a,b,c,d 2. d/dx f(x)g(x)=g*f`+f*g` 3. f`(x)=4x^3+3ax^2+2bx+c x=0 y=2x+1 y=1 (0,1) is a point on f(x) x=1 y=2x-3 y=-1 (1,-1) is a point on...

Homework Statement I am trying to calculate the currents on this 2 power source circuit using Kirchoff's Rules. http://img101.imageshack.us/img101/4151/kirchoffc1.jpg Ignore the numbers on the lines connecting the components and their length Homework Equations I#1=I#2+I#3...

This is a situation that happened back in 2005. I never talked to her ever since, nor am I in love with her. I am just mad at the principle that she felt a need to abide within a framework of a certain "game" and "rules". Here is the thread that describes the situation in more detail...

Homework Statement Use the Wilson-Sommerfeld quantization rules to obtain the energy levels of a perfectly elastic particle of mass m in a cubic box of edge a in terms of the quantum numbers n_x, n_y, n_z Homework Equations \oint pdq = nh Where p is a momentum, and dq is the corresponding...

Homework Statement I am supposed to find the first and second order derivative of p=\left(\frac{q^{2}+3}{12q}\right)\left(\frac{q^{4}-1}{q^{3}}\right) Homework Equations Derivation Sum and Difference as well as Product and Quotient Rules The Attempt at a Solution I tried to cross...

Homework Statement Regarding the identity Ax(BxC) Homework Equations Does this identity only hold when A != B != C?

Hi everybody, I'm new. I'm approaching to QFT in these months and I have a couple of questions about Feynman rules. The most of the books I have read (or tried to) explain feynman rules telling what you have to do when you have an internal or external line in a graph, and when you have a...

Breaking rules of Algebra? Homework Statement I am copying this problem from my textbook. It is about momentum and Kinetic energy The Attempt at a Solution My problem lies in part B. According to Part A, v₁'=v₁‐kv₂' But in part B, (v₁‐kv₂')²+kv₂'²=v₁'², see the problem? v₁‐kv₂'...

Homework Statement The question shows a picture of a general circuit containing two power supplies and three resistors. The equation V=(3R/2)I subscript 3 explains Kirchhoffs Rules. The question asks to rewrite Kirchhoff's rules for the circuit if the power supply with voltage V subscript...

proof for the differential log rule proof for the integral log rule please and thankyou

Is Geography a science? It is comprised of theories, Laws (well Rules realy), hypothesis, some Math equations, aspects of Physics Chemistry and Biology. Also there is still much to be learned from it.

I'm finding a lot of inconsistency with the solubility rules from different sources. especially when it comes to SO4(negative 2 charge). my teacher told me: soluble except when combined with Ca2+, Ba2+, Sr2+, Pb2+... however, other sources sometimes include Hg(II) 2+, and some Ag+, and...

Homework Statement In the circuit of Figure P28.28, determine the current in each resistor and the potential difference across the 200-ohm resistor. Homework Equations Kirchoff's Rules V=IR The Attempt at a Solution The way I did it was like this: I set up a system of...

Homework Statement (p -> q) has an unambiguous meaning both in logic and in natural language. The DeMorgans laws tell us what is meant by the negation of a conjunction or the negation of a disjunction, but what is the negation of a conditional such as p -> q? Use the rules of logic to produce...

I'm reading a course in Introduction to QFT and I'm stuck at a problem. I'm hoping someone here could point me in the right direction or say if my assumptions are incorrect. Homework Statement Derive the Feynman rules and all diagrams at tree-level for \lambda \phi^3 theory using Wick's...