Rules Definition and 539 Threads

Hi, I'm reading Appendix 1 of Section N2 (Gluon Scattering) in "Quantum Field Theory in a Nutshell" by Anthony Zee. The generators for SU(N) have the usual algebra [T^a, T^b] = i \epsilon^{a b c}T^c Suppose we adopt the following normalization \text{tr}(T^a T^b) = \frac{1}{2}\delta^{a b}...

Homework Statement 1-2+3=2: a) 1-2=-1, -1+3=2 or b) -2+3=1, 1+1=2 So you can attack this expression from either side and you still get 2. My question is : If I had to remove logs from lnP= 1/2ln(Q+1)- 3lnR+ 2 I'd either get P=[(Q+1)^1/2]/(R3* e^2) or P=[[(Q+1)^1/2]*...

This isn't really a problem, but more of a conceptual question. I have a circuit drawn (see attached), there are 2 batteries. I don't understand how to split currents at junctions with two batters, It seems like I cannot split the current from both batters at EVERY junction. It's confusing. If...

Homework Statement The nuclear processes obey certain rules. I.e. Conservation of energy and mass Conservation of charge Conservation of spin Conservation of momentum Conservation of lepton and baryon numbers Use the following examples to discuss these various rules in the following...

what rules, energy or entropy?? any physical system goes to a state of maximum entropy or minimum energy, they don`t imply each other, by my understanding 1>third law s->0 as e->0 2>system tends to be in a state of least energy how??

Hrm... Congruence Proofs. Don't remember the "rules" Homework Statement Take equals sign as congruence or equals based on context, please. Itex does not work in Opera. Prove that for all n, 8^n = 1 (mod 7) Homework Equations The Attempt at a Solution This will be a proof by...

Suppose I know that [(P implies ~A) and (P implies B) and (P implies C)] is impossible. Does this means that the following statement is true: [(P implies A) and (P implies B) and (P implies C)]? Any help is greatly appreciated!

AC vs DC! The intent of this post is mostly for aspiring students: When working with one of my students recently….I notice he tends to freak out between the difference of AC and DC……Like they are two completely different subjects. He says one has a frequency and the other doesn’t. I say not...

I am working through this chapter and trying out exercises - I am stuck on this one- this is what I have done so far but since this is my first experience with this topic I am just not sure what to do next i have typed it and attached it here with Thanks Homework Statement I have typed...

Homework Statement f(x) = cos2x - sin2xThe Attempt at a Solution f'(x) = (2cosx)(-sinx) - (2sinx)(cosx) f'(x) = -2cosxsinx - 2sinxcosx This is what I think the answer should be, but the back of the book says otherwise. I need help identifying what I did wrong.

Hi all , I need some help with this problem, Homework Statement A hydrogen atom, which is in its ground state |1 0 0 > , is put into a weak time-dependent external electric field, which points into the z direction: \boldsymbol{E}(t,\boldsymbol{r}) =...

I'm getting confused with the problems that ask you to find potential and when to use the rule that the sum of all the V = 0. There were a lot of questions in my physics book that ask to find a potential in each capacitors and when i was doing those, i just used V = Q/C instead of Kirchhoff's...

Problem: Two automobile batteries are connected in parallel to power a wheelchair. If each of the batteries has electromotive force 12V and internal resistance r=0.025Ohms, and the the wheelchair motor has resistance R=1Ohms, find the current provided to the motor. Attempt at solution: So I...

[b]1. Calculate the three currents indicated in the circuit diagram below. I have attached the diagram. How would I use Kirchhoff's laws to find the currents I am getting thrown off by the third loop.

Homework Statement In this video; the uploader states at 0:47 that there are three rules. 1. Can swap rows 2. Can multiply a row by a constant 3. Can add a multiple of one row to another Do these rules apply only to rows? Can they be applied to columns? The uploader has not stated...

Hi I am reading about transition in Helium, and I have come across a question. It is clear that triplet-singlet transition are not allowed, i.e. ΔS=0. But in my book (Foot's Atomic Physics) it says that Δl = ±1. This is what I don't understand. The selection rule Δl = ±1 we derived for...

There's something that doesn't make sense to me regarding these two rules. I was hoping someone could pat me on the head and tell me that everything was okay, and that both Slater's Rules and Hunds rule were actually complimentary and correct. So when beginning to explain Slater's Rules...

I really need help. I actually don't know how to do this Use Kirchoff's rules to determine I1, I2 and I3 for the following circuit: Circuit figure https://chip.physics.purdue.edu/protected/Prelab221img/e4pp2.jpg E1 = emf = 9 V r = internal resistance = 1.5 R1 = 5 R2 = 15 R3 =...

I have recently seen my Grade 7 brother's maths homework script and I was shocked to find out that he was marked down for not writing down '(Answer)' next to each of the results for his problems. Also, I found out that he was marked down for writing just 'the cost = ...' and not 'the cost of...

I understand that a(b/c) = \sqrt[c]{}(a^b) so this suggests that (-1)(2/3) \sqrt[3]{}((-1)^2) = -1 right? Wolfram alpha and my calculator disagree.

From what I've gathered, certain physical states cannot exist in superposition. When applying the Schrodinger equation to a quantum system, do we get the relevant superselection rule results, or will it produce an answer giving two physical states in superposition, when according to the...

I wanted to know if there are any rules for interpreting mathematical expressions. If we succeed in interpreting a mathematical expression as a physical reality we will make math more friendly and very interesting. What are the rules for interpreting math expressions?

I'm trying to do the following problem: ie. I'm trying to use the Feynman rules for momentum space to write down the mathematical expression that the diagram is supposed to represent. However, I don't feel very confident in what I've managed so far. Now as I understand it, these diagrams...

Question: You have 100 coins. 99 are fair and 1 is double sided. You pick a random coin and flip it 10 times and get 10 heads in a row. What is the probability that you picked the double sided coin? Response / help needed: Probablity of picking a 1 sided coin = .01 Probability of heads 10...

I am detaching this to BSM because it is already getting too much parameters in the bag. What has happened this year is that Werner Rodejohann and He Zhang, from the MPI in Heidelberg, proposed that the quark sector did not need to match triplets following weak isospin, and then empirically...

Homework Statement Calculate the current through the resistor of resistance for circuit B. Express your answer in terms of EMF, R1, and R2. http://imageshack.us/photo/my-images/163/screenshot20111112at110.png/" Homework Equations Kirchhoff's Loop and junction rules The Attempt at a...

Homework Statement A 1.0 g bullet is fired into a 0.5 kg block attached to the end of a 0.6 m nonuniform rod of mass 0.5 kg. The block-rod-bullet system then rotates in the plane of the figure about a fixed axis at A (the figure shows a vertical rod labeled A at its top. A block is attached...

Superselection rules claim that some superpositions are physically impossible. But why are they so? Consider an example from another thread: But why such a superposition makes no sense physically? Clearly, if such a state has been produced from a charge eigenstate, then such a...

Homework Statement Given the following integral and value of n, approximate the integral using the methods indicated (round your answers to six decimal places): \int_0^1 e^{-3x^2} dx n = 4 (a) Trapezoidal Rule (b) Midpoint Rule This is the only one I'm having trouble...

Can someone refer me to Feynman rules for electroweak interactions in the general case of SU(2) multiplets of weak isospin n and weak hypercharge Y interacting with EW gauge bosons? I can only find the standard rules for SU(2) doublet electron - neutrino. Thanks!

If you are given part of a period of a Function, what rules would you apply to draw out the full function, so that it converges as quickly as possible as a Fourier series? thanks

Why is it that you are able to have 1 initial value problem with 2 solutions, but not 2 initial value problems with 1 solution for an ODE? Is there a theorem that states this?

For some reason I am struggling with these problems. I am lost as a goose trying to fly south for the winter! Homework Statement 9^(5-x2) and another derivative problem using chain rule r/square root of the whole term r^2+5 Homework Equations 1st equation= d/dx= a^x ln a 2nd...

I hope its not a problem if I don't have an actual problem. I have a question about partial fractions. When I spilt it into two, the numerator of the original is equal to unknown constant A times secondimerator, plus unknown constant b times first denominator. What if it is spilt into three...

Recent searching of the light from the quasars indicate lack of the quantum fluctuation of the spacetime. http://arxiv.org/PS_cache/arxiv/pdf/1108/1108.6005v1.pdf Does it mean the lack of quantum foam rules out the discretness of the spacetime too ? How to explain Casimir effect and...

There are several rules in calculus which have far reaching applications in field of mathematics, physics etc. unfortunately there is no derivation or visualisation of those rules in my maths book. SO SHAME!. one of these is that definite integral of function from x1 to x2 gives geometrical...

Homework Statement Determine the current in each branch of the circuit shown (here:) [PLAIN]http://img811.imageshack.us/img811/5084/physicschapter2817.jpg Homework Equations Kirchoff's rules, I think is (and I'm probably looking at it wrong): summation of ΔV around closed loops is 0, summation...

I recent.y received a polite warning about a 'jumbled" post. I will try and restructure it. My problem is that I do not speak the same language you do. the numbers do not mean to me what they do to you. So I have to use terms or phrases that will convey my thoughts. In simplistic...

Hi all, I'm trying to calculate the Feynman Rules for the effective electroweak chiral Lagrangian. For example, this is the first term in the Lagrangian: \begin{eqnarray} \mathcal{L}=\frac{v^2}{4}\text{Tr}(D_{\mu}U D^{\mu}U^{\dagger}) \end{eqnarray} where \begin{eqnarray}...

Homework Statement y = ln | sin x | Homework Equations - The Attempt at a Solution No attempt at a solution, because it's more of a "which part of this is incorrect" question. y = ln | sin x | Would everyone agree that this is equivalent? y = ln \sqrt{(sin x^2)} Then...

If I understand right, the rules are: Suppose we want to find net effective charge on an electron in the nth shell. 1) We should ignore the electrons in the higher shells. 2) Every electron in the same shell shield by 0.35 except 1s orbital where electrons shield by 0.3 3)Every electron in...

Homework Statement Let an be monotone sequences. Prove or give a counterexample: The sequence cn given by cn=k*an is monotone for any Real number k. The sequence (cn) given by cn=(an/bn) is monotone. Homework Equations The Attempt at a Solution On the first one, I don't...

The US Supreme Court ruled that http://www.supremecourt.gov/opinions/10pdf/08-1448.pdf. A few things were notable about this decision. For one thing, Scalia and Thomas were on opposite sides of the issue (they almost never disagree on decisions). Secondly, Alito should be commended on his...

I've been thinking about some of the topics where the rules change. For example, - before Plank time - in the core of black holes - at the quantum level - others Do these events/regions/horizons suddenly experience a change in the rules or is it a more gradual change? If some of...

Homework Statement Find the derivative of g(t)=\frac{1}{\sqrt{t}} I cannot use any derivative rules on this problem. Just the difference quotient. It's from the Stewart book (6E, Chapter 3, problem 26). Homework Equations Difference Quotient The Attempt at a Solution Here is where I am at...

Homework Statement Remember to show your working explicitly throughout your answer to this question. (a) (i) Use the Composite Rule to differentiate the function f(x) = (x^2− 6x + 23)^(3/2) (ii) Use the Quotient Rule and your answer to part (a)(i) to show that the function: g(x) = (x −...

Homework Statement f(t) = t^2- \sqrt{t} Find f'(t) Homework Equations Difference Quotient The Attempt at a Solution f(t) = t^2-\sqrt{t} \lim_{h\to0} \frac{(t+h)^2-\sqrt{t+h}-t^2+\sqrt{t}}{h} \lim_{h\to0} \frac{t^2+2th+h^2-\sqrt{t+h}-t^2+\sqrt{t}}{h} \lim_{h\to0}...

Consider question 1 in this paper: http://www.maths.cam.ac.uk/postgrad/mathiii/pastpapers/2002/Paper65.pdf How do we "read off" the Feynman rules? I can see that the interaction terms give contributions \lambda_3 , \lambda_4 , \lambda_6 to the relevant 3,4 and 6 point vertices respectively...

Consider equation 5.46 in these notes: damtp.cam.ac.uk/user/tong/qft/qft.pdf (i) why does only one term have the i \epsilon in it? I thought this was because the (p-p')^2-\mu^2 term can never vanish but this doesn't make sense since the \phi particle will have momentum p-p' and since momentum...

I'm not always on the same computer, often times I'm using my phone to look for answers when doing physics on the go. Does anyone know a good, correct resource for ALL of the tree level feynman rules for QED+EW+QCD? Feynman gauge would be preferred, or ungauged. I can find most for the...