Particle physics Definition and 514 Threads

Homework Statement A reactor fires out ##10^{21}## neutrinos per second. A detector containing ##10m^3## of liquid which contains 30 carbon atoms every 60 hydrogen atoms. The detector-reactor distance is ##1000##. The cross section for the reaction is ##\sigma = 10^{-46} m^2##, and the density...

I was wondering are there any experiments to distinguish between 2 and 3-body decays? For example, consider decay of the muon and the pion: The pion only emits 1 muon neutrino ("missing energy") and 1 muon. The muon however, emits 1 muon neutrino, 1 electron neutrino and 1 electron. How is...

Hey physics enthusiasts, I have been reading and watching various videos, which talks about the possibility that the Higgs particle which was discovered by collisions in the large hadron collider(LHC) may not be the standard model Higgs particle. What does this mean? What is the difference...

Homework Statement Calculate the ratio ##R = \frac{\sigma_{had}}{\sigma_{\mu+\mu-}}## for energy around ##10~GeV##. At sufficiently high energies, the ##e^+e^- \rightarrow \mu^+ \mu^-## reaction can proceed via the ##Z^0## boson. Assuming vertex factors for EM and weak interaction are the same...

Homework Statement Neutrinos with energy of about ##1 GeV## are measured in an underground detector and compared with simulations of neutrinos produced in the atmosphere. Measured flux of upward going muon neutrinos ##(\nu_\mu + \bar \nu_\mu)## is half compared to simulations while measured...

Hello I am an incoming Biology student (college), i really wanted to take applied physics as my course but my parents told me that it is better to be a doctor, anyways, it's summer here and I started taking Calculus 1 in coursera.com (i have NO backgroud in calculus because we don't have...

I want to do research as a physicist on either particle physics or quantum theory.For that I wish to pursue higher degrees in world's leading institutions of physics.What should be my career path after i complete my graduation in Physics which i am presently persuing.

Today is an exciting day, for today will see a new record for the highest energy collisions at the LHC - stable 13 TeV collisions for new physics, signalling the start of the new physics program at the LHC! There are a few ways you can keep track of progress throughout the day. The LHC status...

Homework Statement (a)Draw feynman diagrams of upsilon meson. Why is decay to ##q\bar q## states suppressed? Explain why width for 4s is much wider. (b) How do B mesons decay? Why is no other type of interaction possible? Draw feynman diagrams. (c) Find the distance traveled by 1s and 4s. (d)...

Homework Statement [/B] (a) Find the ratio of cross sections. (b) Find the cross section for electron-neutrino scattering by first writing down relevant factors. Homework EquationsThe Attempt at a Solution Part (a)[/B] These represent the neutral current scattering for the muon-neutrino and...

We know that there are 3 generations of neutrinos, namely the electron neutrino, muon neutrino and the tau neutrino. The masses are all very small compared to their respective leptons. What evidence is there that these neutrinos of different generations are distinct?

If you consider the ##\chi_0 ## with a mass of ## 3.4 GeV/c^2## meson, why doesn't it decay to a pair of charged leptons? Technically it is possible though the weak interaction (Z boson) or EM interaction, right? Is it because it is so heavily suppressed because the strong interactions are...

Homework Statement Question: Figure 1: QUESTION ABOVE. Homework Equations The Attempt at a Solution :[/B] P + P → K+ + K- + P + P Firstly, I just wanted to check that this is correct. I found the answer pretty quickly by googling it but have since spent a long while trying to understand...

Suprisingly I am looking for a good introduction to particle physics, that is of course non comercial (not something like brian greene) but with serius maths with good excersises. Thanks for any advise.

I'm currently writing a paper for a small class called "Contemporary Physics" and I am writing about particle accelerators and the search for the Higgs Boson. I have a fairly good idea about how the Large Hadron Collider works, but I cannot use my own explanation alone as I need references to...

Homework Statement (a) Draw the feynman diagram for ##p \bar p \rightarrow## reaction. (b) Find an expression for mass of the particle. (c) Find an expression for number of ##\mu^{+} \mu^{-}## produced. (d) Find an expression of ##n_{jj}## in terms of ##m_{inv}## and its spin. (e) Deduce the...

I was studying my notes and specifically for the ##e^+e^- \rightarrow \mu^+ \mu^-## process, cross section is given by \sigma = \frac{4\pi}{3} \left( \frac{\alpha \hbar c}{W} \right)^2 where ##\alpha = \frac{g_{EM}^2}{4\pi}## and ##W## is the centre of mass energy. Is this the same for...

Homework Statement (a) Explain the results. (b) Why is the cross section much higher? Suggest the dominant decay product pair.[/B] Homework EquationsThe Attempt at a Solution [/B] Part(a) For a centre of mass energy of ##170GeV##, you produce pairs of oppositely charged ##W^{\pm},W^{\mp}##...

Homework Statement (a) Explain spin and parity of mesons (b) State their quark content (c) Draw a feynman diagram of J/psi decay (d) Why doesn't ##\chi## undergo leptonic decay? (e) What is the minimum centre of mass? [/B] Homework EquationsThe Attempt at a Solution Part(a)[/B] Spin is...

Homework Statement (a) What is a meson? (b) State what these mesons are made up of and explain their quantum numbers and interactions. (c) Find the lifetimes of rho meson and kaon. (d) Find the dominant decay mode and explain why. (e) Why is decay to 2 neutral pions forbidden? (f) Explain how...

Hi all, I make some exercises in particle physics but I'm stuck in two problems related to Gamma matrices identities, First: the Fermion propagator ## \frac {i } { /\!\!\!p - m} = i \frac { /\!\!\!p + m } { p^2 - m^2} ## So how ##/ \!\!\!\!p ^2 = p^2 ## ? Where ## /\!\!\!p = \gamma_\mu p^\mu...

Hey I'm new to this forum and I'm 14 and I want to be a future Physicist (Probably Particle Physicist ) and I was wondering what books are good for starting out , just to let you know what kind of content I'm looking for I already know about General relativity , special relatativity , and the...

Hi all, I'm a Usman,a physics student from Pakistan .I have joined this forum to polish my physics skills and to share whatever I know about physics ,its principles and so many on......:smile::smile::smile::smile::smile::smile:

I had a lot of trouble in my early undergraduate career and had received some really bad grades. I retook a lot of courses and after 6 years, I am finally graduating with good marks in my third and fourth year courses and I believe I have an overall good understanding of undergraduate physics. I...

Homework Statement Okay, here's the deal:I have been given a second order nonlinear differential equation, and I have also been given the general solution with constants A and B. I am supposed to find the constants A and B. The solution represents a fermion at rest, since the solution does not...

Homework Statement Draw feynman diagrams for pi+ muon lepton decay and suggest which process is more likely.Homework EquationsThe Attempt at a Solution [/B] The feynman diagrams are: The lepton decays proceed via the weak interaction W+ boson. This implies that e+ should be...

Homework Statement I am making an old exam of a particle physics course, and i know how to calculate the cross section for example for bhabha or moller scattering. now one of the questions on the old exam is: Explain why e-+ e+ -> γ is zero, but i am not sure why this is, can someone explain...

Homework Statement (a) What are the branching ratios for EM decay only? (b) What does this reveal about the strength of strong interaction? (c)What are the relative rates of decay? Homework EquationsThe Attempt at a Solution Part (a) [/B] For EM-only decay, the branching ratio would be...

Homework Statement (a) What are their vertex and propagator factors? (b) Find the value of R. (c) Explain the peaks at 3, 10 and 100 GeV. Homework EquationsThe Attempt at a Solution Part (a) They have the same propagator factor ##\frac{1}{P \cdot P}##. Vertex factor for muon production is...

Homework Statement 1. If a charged particle moves in a straight line through some region of space, can you say that the magnetic field in that region is zero? Explain. 2. How can the motion of a charged particle be used to distinguish between an electric field and a magnetic field? 3. If a...

Hi guys! Sorry for a really dumb question, but I want to study particle physics more in depth, since our university course didn't really satisfy me that much (and, when it comes to physics, I want to know everything I can get to). Can someone give me a general list of things I should know and...

Homework Statement (a) What shows the existence of shell structure? What are the other numbers? (b) Deduce the spin and parities. Homework EquationsThe Attempt at a Solution The shell model is given by: So for Li, 3 protons pair up with 3 neutrons, leaving an unpaired neutron in...

I don't know much about particle physics, but out of curiosity I was wondering what would happen if a stream of electrons hit a conductor, say copper plating, an would it be detectible?

I am constructing a linear particle accelerator and have come into a problem, I need a materiel that when a electron hits it the electron breaks apart in smaller particles and the materiel breaks apart (on the subatomic level of course) as little as possible and make a little exes radiation as...

Homework Statement Why does ## \frac{ e^+ + e^- \rightarrow \mu^+ + \mu^- }{e^+ + e^- \rightarrow \tau^+ + \tau^- } \rightarrow 1## at high energies? Would it be the same if it was ## \frac{ e^+ + e^- \rightarrow \mu^+ + \mu^- }{e^+ + e^- \rightarrow e^+ + e^- }##? Homework EquationsThe...

Homework Statement (a) e- + e+ -> e- + e+ (b) e- + e- -> e- + e- c) e- + e- -> e- + e- + u+ + u- d) y -> e+ + e- e) y + y -> y + y Homework EquationsThe Attempt at a Solution Part (a)[/B] Part (b) Part (c) Part (d) Part (e) Not sure what to do with this, since usually the...

Hi, sorry if this is a novice question. I've recently been introduced to Q value in nuclear and particle physics and all the places I've looked at define it as the change in rest energy between the initial particles and final particles. ##Q=E_f-E_i=(m_f-m_i)c^2## But this doesn't take into...

I am currently in my first year of A levels and we have completed the particle physics parts of this year and by asking my teacher and A2 physics students I have found that next year we will not be going into much more detail regarding particle physics. This left me somewhat disappointed as I...

Hi everyone, As of late I've been really wanting to push on with my interest in particle Physics by tackling the rather daunting theoretical model that we call supersymmetry. However, to put it simply, I'm not entirely sure where to start! There's so many different textbooks on the subject out...

Things I don't understand: What do they mean by "two spin-1/2 doublets and a spin-3/2 quadruplet"? Why do they use the two flavours "+2/3e and -1/3e" ?

Hi all! My name is Mike. I would like to new the recommended course of study for someone who wanted to know all there is to particle physics through self study. I've done the derivatives and beginning integration in calculus and have just begun the first year physics text. Could someone please...

Homework Statement a) Particle A decays at rest into two photons. Calculate, in terms of the rest mass of A, the energy and momentum of each photon. b) In a different reference frame, particle A is initially in motion such that its kinetic energy is equal to its rest energy. Find the momentum...

Please explain how is exactly strong force caused, I've come across various answers but haven't yet received a complete answer. What is the nature of the strong force? P.S: If this is the wrong thread, Please RE-LOCATE and do not remove please. :)

Hi all. I'm a prospective physics major, hoping to either go into particle physics or condensed matter research or enter tech if research doesn't turn out to be for me. I was wondering which elective I should choose for next semester--astro 101 or Chemistry 1 or CS 1? Will chemistry help me with...

Hello! I am a new member of this forum. Some of the google searches i made gave wonderful results to the questions i asked. I am really interested in studying particle physics and cosmology. I want a guide to how i would specialise in the subjects and the career options. There are a lot of...

Hi. I was reading an introductory book about particle physics and I visited the PDG for an exercise. I found this... http://pdg.lbl.gov/2014/tables/rpp2014-tab-mesons-strange.pdf On page 9, the data of K1(1270) is given. How do I figure out it's quark content? If I look at the data for K*(892)...

I know it's probably simple but I just don't understand reduced mass. I am trying to work out the reduced mass of 4He+. m = memN / me + mN Can somebody please just explain step by step what I do. This is only a segment of a 1 mark question and I'm getting my knickers in a frustratingly twisty...

According to the equation F=BQ/2pieM the frequency depends on the magnetic field and not the speed or radius of the particle. Can someone please explain why? B= Magnetic field strength Q=Charge M=Mass I think it's because of the force felt due to magnetic field so the time it reaches the dees...

Since in particle physics c can be take to equal 1, does this mean that Energy can equal mass if we use electronvolts ?

Homework Statement This is a question on multiple coulomb scattering in a wire chamber momentum p = 500MeV/c wire resolution = 120 microns distance from wall to wire = 0.01m radiation length of wall material X_0 = 2E-3 m mass of charged particle m_{\pi} = 139.6 MeV/c^2 charge z = 1 How thick...