Decay Definition and 998 Threads

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...

Homework Statement [/B] (a) Explain lepton universality. (b) Explain why decay mode is forbidden and find hadronic branching ratios. (c) Find the lifetime of tau lepton. (d) What tau decay mode would be suitable? (e) Find the precision. (f) How do you improve the results? (g) Why is it much...

Why is the decay ##\tau^{-} \rightarrow \mu^+ + \mu^- + \mu^-## not allowed? Charge, lepton number are conserved. I have a feeling it is something really basic. I'm thinking in weak interactions you only go from a ##l^- \rightarrow \nu_{l}## and not 'hop' from one muon to another non-neutrino muon.

From particle data group,(http://pdg.lbl.gov/2014/listings/contents_listings.html) I can see the decay branching ratios of N(1875),but the total width is not found.The "Breit Wigner width " are very different.So my question is ,How do they get the branching ratio without a certain total width?

Homework Statement Nucleus ##^{252}_{98}Cf## alpha decays with half life time ##t_{1/2}=2.6## years. What is the velocity of the alpha particle after the decay? Estimate the half life time of the nucleus after the decay. Homework EquationsThe Attempt at a Solution Ok, no worries about the...

Homework Statement If we have a beta + deca: $$^{22}_{11}Na(3^+)\rightarrow ^{22}_{10}Ne(2^+)+ e^+ +\nu $$ with $t_{1/2}=2.6 years$, what is the energy balance at this decay, if you know that $^{22}_{10}Ne(2^+)$ is an excited state of $^{22}_{10}Ne$ with $1.25 MeV$ larger energy. Homework...

Homework Statement Homework Equations See below. The Attempt at a Solution We have β+ decay ##X_{Z}^{A} \rightarrow Y_{Z-1}^{A}+ e^{+}+\upsilon _{e}## which leads to the mass condition ##M(A,Z)>m(A,Z-1)+2m_{e}##. We have electron capture ##X_{Z}^{A} + e^{-}\rightarrow Y_{Z-1}^{A}+ \upsilon...

Homework Statement The number of radioactive nuclei in a particular sample decreases over a period of 26 days to one-fifteenth of the original number. What is the half-life of the radioactive material, in days? Homework Equations R=DN/Dt=(lambda)(N)=(N)(ln2/T1/2) The Attempt at a Solution...

Homework Statement The question is that the decay modes for the ##W+## boson are , ##e^+ v_{e}, \mu^+ v_{\mu}, \tau^+ v_{\tau}, ud', cs' ##, where a ' denotes a anitquark, neglecting the masses of the decay products estimate the branching ratios of the ##W+##? Homework Equations N/A The...

For β- we have: ##M(A,Z)>M(A,Z+1) + m_{e} - m_{e}## An electron is removed from the atom and therefore we need to take that away from the M(A,Z+1) term But for β+ we have been given: ##M(A,Z)>M(A,Z+1) + m_{e} + m_{e}## What is this saying? A positron is emitted, therefore shouldn't we minus...

Consider ##\Sigma^0 \rightarrow \Lambda + \pi^0##. (Not Allowed) According to griffiths, this strong interaction is not allowed by 'Conservation of Energy'. I'm not sure why, as this simply shows an up and anti-up quark coming together, producing a gluon, where mass of gluon is mass of up and...

My textbook says: One of the decays occurs via a ## b \to c ## quark transition and is 'colour-allowed'.(Left of diagram). The other decay has a of ## b \to c ## and is 'colour-suppressed'.(Right of diagram) I'm unsure of what is meant by these terms, it doesn't really explain. I've...

Homework Statement A pion at rest (mπ = 273me) decays into a muon (mμ = 207me) and an antineutrino (mn ≈ 0). Find (a) the kinetic energy of the muon and (b) the energy of the antineutrino in electron volts. Homework Equations K = (γ-1)mc2 E = γmc2 ER = mc2 E2 = p2c2 + (mc2)2 I didn't...

Hi there, In Reference as hep-ph/0306037v2, we see the effective Hamiltonian of ## B \to l \nu ## equ. 1, which has the SM and the NP parts. In equ. 4, it seems that ## m_l ## comes from ## P^\mu_B ## equ. 3. The question that how ## P^\mu_B ## yields ## m_l ## ? Where ## P^\mu_B = ( E_B, 0...

Area under decay curve exp(-0.6969t/h) where t is the time (with t=0 initially) and h is a constant "half life" is analytically integrable, but what if the half life is increasing with time? I. e. if h(t) = H + at. (Note exp(-0.6969) is not exactly 0.5 but close and easy to remember.) This...

Hi there, In a reference as 1303.5877v1 [hep-ph ] the SM branching ratio of ## B \to \tau \nu ## is given by: ## \frac{m_B G_F^2 m_\tau^2 \tau_B f^2_B } { 8 \pi } V_{ub}^2 ( 1 - \frac{m_\tau^2}{m_B^2} )^2 ## . In the SM model the value of this BR ## \sim 0.7 \times 10^{-4} ## . But I don't...

Wonder if our resident researchers and scientists feel this way? http://arxiv.org/pdf/1503.01881v1.pdf

The question is for which of the ##1P## meson states - ##1^{1}P_{1}, 1^{3}P_{0},1^{3}P_{1}, 1^{3}P_{2} ## ##D_{s}## states decaying to a ##1S## state is the decay: ##D_{s}**^{+} -> D_{s}^{+}\pi^{0} ## possible? Solution So the strong interaction conserves parity. Parity of meson is given by...

Is it possible to produce the inverse of a natural radioactive decay? If yes, what would happen? Release energy?

Homework Statement Professor X, a nuclear physicist who works at the MSU FRIB facility, has designed a new particle detector called The da Vinci Decoder. Using this detector, she has discovered a new particle dubbed particle X that violates lepton number conservation. A stationary X is observed...

Hi, I'm working on an assignment in which the following reaction takes place: \nu_e e^- \rightarrow \nu_e e^- And I'm wondering whether its possible to have an electron neutrino and an electron annihilate to form a W^- boson, after which that boson decays into a \nu_e e^- pair...

Homework Statement [/B] 1.) A muon is created by a cosmic ray interaction at an altitude of 60km. Imagine that after its creation, the muon hurtles downward at a speed of 0.998, as measure by a ground-based observer. After the muon’s “internal clock” registers 2.0μs , the muon decays? a.) If...

I am a non physicist-scientist, but landed here searching the internet for this answer. Has it ever been done? Thank you for any answers.

1. The Problem Construct a mathematical model (system of differential equations) for a radioactive series of 3 elements. X,Y, and Z (Z is a stable element). (Note: W decays into X, X decays into Y, and Y decays into Z). At time zero there are 100e (approx. 271.828) moles of element X. After two...

The basic "nuclear physics for dummies" explanation of nuclear physics goes something like this: There are two dominant forces at play in atomic nuclei: the residual strong force (aka the nuclear force) which binds nucleons together and the electromagnetic force (or, more simply, the...

Hi there, Since some time I started to study the semilptonic decay of B meson : ## B \to D \tau \nu ## that there is an excess in the value R (D) = ## \frac{ Br ( B \to D \tau \nu) } {Br (B \to D l \nu) } ## in BABAR experiment than the SM expectations- See for example arXiv:1302.7031v5- Now I...

Hi there, I have a a partial decay width in form of ## \frac{d \Gamma}{d \cos{\theta}~ dq^2} = ## some terms functions in q and ## \theta ## variables. How to integrate this decay width in Mathematica over this two variables ? I tried some thing like j[q_]:= ## \int_{1}^{-1} ## Gam[q, ##...

So I have a problem where I'm given the decay rate of a sample which contains Cs137, 10 mCi, and I'm basically given the percentage of radiation detected by the detector. But the wording of the question is: "What count rate would be observed in a perfectly efficient gamma detector" Sounds to...

Recently there was an interesting thread on physics forum about possible uses of spent nuclear fuel. It seems to me that one of the problems with using decay heath from spent nuclear fuel is the low power density. This got me thinking that maybe with enough insulation the low quality heat...

Hello. I want to play around with the process of one photon splitting into more lower energy photons and vice versa. As I understand it one can quite easily make a Feynman diagram of a photon splitting into two lower energy photons by interacting with virtual electron/positrons. And also the...

how can we guess the possible decay modes for an element with three given quantities: A, Z and mass difference in MeV

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...

Homework Statement Homework EquationsThe Attempt at a Solution i believe that a half-life of several years is too long to gather the data but i can't figure which of the 2 emitter and why? the answer is given to be C

Homework Statement Calculate the activity of ##^{222}Rn## in an ore sample containing 5g of natural uranium. Homework Equations ##^{238}U## decay chain (to Radon): ##^{238}U\rightarrow^{234}Th\rightarrow^{234}Pa\rightarrow^{234}U\rightarrow^{230}Th\rightarrow^{226}Ra\rightarrow^{222}Ra##...

1. The half-life of 238 92U is 4.5 × 109 years, which is much larger than all the other half-lives of the decays in the series. A rock sample when formed originally contained 3.0 × 1022 atoms of 238 92U and no 206 82Pb atoms. At any given time most of the atoms are either 238 92U or 206 82Pb...

We consider the following beta decay: ^A_ZX \rightarrow ^A_{Z+1} Y + e^{-} + \nu_e The Fermi golden rule is given by: \Gamma = \frac{2\pi}{\hbar} |A_{fi}|^2 \frac{dN}{dE_f} Reaction amplitude is given by ##A_{fi} = G_F M_{nucl} ## while density of states is given by ##dN = \frac{4 \pi...

Although it was drummed into me that electrical neutrality is preserved, I am perplexed by the phenomenon of radioactive decay. How is electrical neutrality maintained when electrons (beta particles) and proton-neutron sets (alpha particles) are being spit out by some elements. These particles...

Hi, I'm really struggling to comprehend how the Bohr model solves the problem of accelerating electrons losing energy and decaying into the nucleus. I've read through a lot of discussions on line and on PF and all I keep on reading is stuff like, the quantization of energy levels leads to a...

I have this true and false question: " The half life and therefore the decay constant will be the same for every isotope a) True b) False c) only if it is an isotope of the same element " I think this is false, just by intuition.

Homework Statement Analyzing 1000 events (each event is one radioactive decay of an unknown sample), we notice that the time between two consecutive events is larger than 1 second in 30% of the cases while in 5% it is longer than 2 seconds. Can we, at 5% risk level deny the hypothesis, that the...

For a definite particle,the decay mode is determinant,finite kind,which embody the characteristic of quantum mechanics. But for a specific mode of a definite particle's decay,the decay spectrum,ie,energy of products,continuous,or discrete? Decay is a process which has unique initial...

I am concerned about the idea of decay of HB... when two photons collide in Hadron .. exploding outward.. as the proton remnants leave trails in the field surrounding .. revealing a smaller particle field which quickly disappear... My contemplations lead me to think they do NOT quickly decay...

Homework Statement Magnesium (Z = 12) has isotopes that range from Mg–20 to Mg–31. Only Mg–24, Mg–25, and Mg–26 are not radioactive. What mode of radioactive decay would convert Mg–20, Mg–21, Mg–22, and Mg–23 into stable isotopes most quickly? (A) electron emission (B) alpha particle emission...

Excited baryon could decay into photon and ground state baryon,but could it decay into omega meson and ground state baryon?Could you introduce me some articles about it,experimental or theoretical?

I come cross one proof the Landau-Yang Theorem, which states that a ##J^P=1^+## particle cannot decay into two photons, in this paper (page 4). The basic idea is, the photon's wavefunction should be symmetric under exchange, however the spin part is anti-symmetric and the space part is...

Here is the question, I was able to complete part a and b but c has beaten me! A pi meson has rest mass 131 MeVc-2 and total energy 1.000 GeV a) What is its momentum, expressed in MeVc-1 For this I obtained 991 MeVc-1 using the equation E2=c2p2+M2c4 b) By how much is its speed less than...

Hi, I was reading about free neutron beta decay the other day and it came to me the idea of neutron stars. As I understand, neutron stars are held together by gravity instead of strong force interaction (which I think is the mechanism that gives stability to neutron in common nuclei). So one...

This may be a silly question, but what prevents the decay of a Pion into a (anti) Tau and (anti)Tau neutrino. I can see the process for the electron but not for the tau.

Homework Statement superman has been disabled by a nearby amount of kryptonite, which decays exponentially. If Superman cannot regain his power until 90% og the kryptonite disintegrates, then how long will it be before he regain his powers? Use r=-0.138629. Round to the nearest day. a. 4days...

Homework Statement The ##B^+## meson decays through the weak interaction. One of its decay channels is . If a ##B^+## is traveling with a total energy of 9.90 GeV, calculate the range of possible energies the produced may have. (i.e. determine the minimum and maximum values of its energy.)...