In nuclear physics and particle physics, isospin (I) is a quantum number related to the up- and down quark content of the particle. More specifically, isospin symmetry is a subset of the flavour symmetry seen more broadly in the interactions of baryons and mesons.
The name of the concept contains the term spin because its quantum mechanical description is mathematically similar to that of angular momentum (in particular, in the way it couples; for example, a proton-neutron pair can be coupled either in a state of total isospin 1 or in one of 0). But unlike angular momentum it is a dimensionless quantity, and is not actually any type of spin.
Etymologically, the term was derived from isotopic spin, a confusing term to which nuclear physicists prefer isobaric spin, which is more precise in meaning. Before the concept of quarks was introduced, particles that are affected equally by the strong force but had different charges (e.g. protons and neutrons) were considered different states of the same particle, but having isospin values related to the number of charge states. A close examination of isospin symmetry ultimately led directly to the discovery and understanding of quarks, and to the development of Yang–Mills theory. Isospin symmetry remains an important concept in particle physics.
Homework Statement
There are a lot of similar problems so it is a general question, if you have a nuclear reaction with two particles before, and two afther the process ¿How do you calculate if the Isospin is conserved?¿or the angular momentum?.
For example(it could be any other) we have...
I'm losing my mind trying to differentiate spin, isospin, weak isospin; then there's chirality, helicity - i must be dyslexic and quantumly challenged.
Since it would be a monumental undetaking to do this online, does anyone know of a reliable source i can access online (other than wikipedia...
I am given this next question:
Show that the new resonance Z+[4430] which is too heavy to consist entirely of d and u quarks cannot be a meson (which constitues from a quark and an anti quark).
I am given that it's decay in a strong interaction to particles \psi',\pi^+
And I know that the...
Homework Statement
Part A)
Establish which of the following combinations of particles can exist in a state of I=1 :
a) \pi^0\pi^0
b) \pi^+\pi^-
c) \pi^+\pi^+
d) \Sigma^0\pi^0
e) \Lambda^0\pi^0
Part B) of the problem is:
In what states of isospin may exist the following systems?
f)...
Hi,
I'm having a little bit of trouble with isospin. What I have gathered so far is that say, for the proton and neutron, apart from their charge they are very similar, so they are considered to be different states of the same particle called the nucleon.
So, we say the nucleon has an...
How is weak isospin conserved?
Before spontaneous symmetry breaking, it's conserved - by construction.
Afterwards, the vacuum expectation value of the Higgs breaks the symmetry.
It's the mass terms, and interactions of the Higgs field, where the symmetry is broken, and so there is no...
seems like a basic question and I'm sure many would answer that these are
all "spin-1" particles...but that's not their "isospin", right? can someone in the
know please straighten things out.
The Gell-Mann - Nishijima relation can be rearranged to show that there is an absolutely conserved quantity which is like a generalization of I3 for anything made of quarks:
Q - \frac{B}{2} = I_3 + \frac{(S + C + B^* + T)}{2}
Since the LHS terms are absolutely conserved individually, the...
The G-partiy of the pion is -1, which is rotation in isospin space around y-axis by angle \pi followed by C-conjugation.
The rotation matrix around y-axis , with angle \pi , is: (e.g. Sakurai, Halzen ..)
\begin{pmatrix}0 & 0 & 1 \\ 0 & -1 & 0 \\ 1 & 0 & 0 \end{pmatrix}
Thus on \pi^+ : T...
Hi there! Doesn't seem like a hard problem..
Homework Statement
Show that the 3 isospin operators, defined by T_{+}\left\vert p\right\rangle =0, T_{-}\left\vert n\right\rangle =0, T_{+}\left\vert n\right\rangle =\left\vert p\right\rangle, T_{-}\left\vert p\right\rangle =\left\vert...
Hi,
I'm an undergrad physicist in a bit of a pickle over how isospin relates to scattering amplitude.
It's been quoted to me that the scattering amplitude is given by the matrix element of the initial and final isospin states. I'd ideally like to show you this in latex, however I can't...
I am a general reader.I found in a book:"Three quarks with I=(1/2) can combine to form I_tot=(1/2) [did not understand] or (3/2) [OK].I_tot = (1/2) gives the nucleons while I_tot = (3/2) forms the baryons.
Now,using u and d isospin doublet,I expressed the baryons:uuu,uud,udd,ddd.And found...
Hi All,
I'm wondering what the difference is between flavor and isospin.
If you own a book by Griffiths titled Elementary Particles, on page 183 in the paragraph above EQ 5.129, he mentions isospin and spin together and the former seems to imply the latter.
Does anyone out there know...
This is from Krane, p 389:
The neutron and the proton are treated as two different states of a single particle, the nucleon. The nucleon is assigned with a fictious spin vector, called isospin.
Nucleon has isospin number t = ½, a proton has m_{t} = 1/2 and neutron has m_{t} = - 1/2 .
The...
Homework Statement
Show that
R_2 \left| I \; 0 \right> = (-1)^I \left| I \; 0 \right>
where
R_2 = e^{i \pi I_2}
N.B. the isospin states are represented by the usual notation of
\left| \textrm{(total isospin}) \qquad \textrm{(isospin component in the z direction)} \right> The Attempt at...
Hi you guys!
I am a little bit confused about nuclear isospin.
u and d quarks have I = ½
u has I_3 = ½ , d has I_3 = -½ (third component)
right so far?
Now why does the proton have I = ½ and I_3 = 1/2, and
neutron I = ½ and I_3 = -1/2 ??
but when you add upp the I on the...
This may sounds like a dumb question but I want to figure out the 'point' of them.
I know that isospin was an attempt to describe the proton and nucleon as an isospin doublet and that hypercharge seems to me to be a nifty little relation between the electric charge and the isospin - but what...
I have a problem in understanding the dependence by isospin of strong interaction.
In this potential one have a lot of operatorial terms which include central, spin-spin, tensor force, spin-orbit terms, and all this four terms multiply by a factor isospin-dependent (tau_i dot tau_j).
I don't...
I'm curious about the isospin of a photon. I have been told it is a linear combination of I=1 and I=0. If I=0, then I3 must be 0, but if I=1, what values of I3 are allowed?
I don't really have a good idea of how to think about the isospin of this boson because I can't break it down into...