Questions tagged [baryons]

Baryons are hadrons (particles composed of quarks) with an odd number, at least 3, of valence quarks. The term is also often used in astrophysics, e.g. "baryonic matter", with a much looser definition understood to mean any matter composed mostly of baryons, but which may also include leptons and other particles, often in opposition to "dark matter".

Filter by
Sorted by
Tagged with
-1
votes
2answers
114 views

Can indistinguishable particle wavefunctions be written as a product of total observable eigenstates?

Consider the wavefunction of say two electrons in an external potential, associated with two possible states $\phi_a$ and $\phi_b$. Furthermore, each electron can have two spin states $\chi_1$ and $\...
0
votes
0answers
14 views

Can a baryon consist of two quarks and an antiquark? Or a pentaquark be made of three quarks and two antiquarks? [duplicate]

I suspect these particles exist, but are extremely short-lived, even compared to other unstable, exotic particles...
0
votes
1answer
27 views

Baryon number vs electromagnetic charge, what is the difference?

What exactly is a Baryon number? I looked up definition from wikipedia and still struggle to understand this. And how does this differ than the electromagnetic charge? My textbook did the following ...
1
vote
0answers
48 views

Understanding Baryonic Acoustic Oscillations

I was reading the book of Barbara Ryden "Introduction to cosmology": In the chapter number 9, in the page 203. She says: "The photons, electrons, and protons together make a single ...
0
votes
0answers
45 views

Why is the density of atoms in space so much higher than the baryon density from BBN and CMB?

If you ask the question: "how many atoms per cubic meter in space", you can get a consensus of around $5$ atoms per cubic cm or about $5\times 10^6\space \text{atoms}\space m^{-3}$. If we ...
0
votes
0answers
32 views

What is the (model independent) density of baryons in the Universe?

I know that Planck has measured the baryon density, $\Omega_B$, as a fraction of the critical density, $\rho_{CRIT}$. Is there a measurement of baryon density that's independent of the critical mass ...
5
votes
1answer
166 views

Why are semileptonic decays of the $\Lambda$ baryon so suppressed?

Looking at the Particle Data Group tables of the $\Lambda$ baryon, I find that the rate of the hadronic decay $\Lambda \to p \pi^-$ is 64% while the semileptonic decay $\Lambda \to p e^-\nu_e$ has the ...
3
votes
1answer
119 views

Why are the lifetimes of the neutral and charged $\Xi$ hyperons so different?

According to the Particle Data Group, the lifetimes of the neutral and charged $\Xi$ baryons differ significantly: $\tau(\Xi^-) = (1.639 \pm 0.015) \times 10^{-10}$ s, while $\tau(\Xi^0) = (2.90 \pm 0....
1
vote
1answer
33 views

What is a “multicharge nuclei”?

When doing some reading on particle physics, I came across the concept of a "multicharge nuclei". A Google search of this phrase returns a number of research papers, but no definition for what a "...
0
votes
1answer
38 views

Fujikawa Jacobian for Baryon number anomaly

Reviewing the anomalies of the standard model, one knows that the Baryon number is not conserved because of an anomaly associated to the global $U(1)$ symmetry that quarks have. That is the current $$...
6
votes
1answer
95 views

Baryons in flavor $SU(N)$ (in ChPT)

For flavor $SU(2)$ (Isospin) we have two $\frac{1}{2}^+$ baryons, the nucleons. For flavor $SU(3)$ we have the eight baryons in the octet. In a world with $N$ light quarks we would see a baryon ...
5
votes
0answers
64 views

Chiral WZW term for Hadron Supersymmetry?

Remarkably, an approximate supersymmetry not in the color- but in the flavor-sector is experimentally observed: hadron supersymmetry, relating mesons (the bosons) to baryons (the fermions). The most ...
4
votes
0answers
62 views

Spin of skyrmion

Baryons can be considered as solitions in Skyrme model(See also this post.): Such Lagrangian haven't any information about number of colors. Bosonic or fermionic nature of baryons depends on number ...
0
votes
1answer
29 views

What can we conclude for the spin configuration of the quarks inside the baryon? [closed]

If yes, is there any way to reconcile this findings with Pauli's exclusion principle?
3
votes
1answer
98 views

One-form current in 3d QED

3d QED in IR can be described in terms of dual scalar field $\varphi$ have trivially conserved current with two indices, associated with U(1) one-form symmetry: $$ J_{\mu\nu} = \epsilon_{\mu\nu\rho}\...
2
votes
2answers
78 views

Holographic dual to baryon

Baryons can be effectively described at low energies as solitions in Skyrme model, that describe pions as NG bosons. In Skyrme model exist current, that can be identified with baryon number current, ...
0
votes
1answer
39 views

Resourcs on learning about 2-body resources

As a part of my Particle Physics Course, I will need to give a talk on 2-body resonances - What are they? Some examples like 𝐽(Ψ), Z boson and significance of those discoveries. I am looking for ...
1
vote
1answer
107 views

$\Sigma^0$ and $n$ decay

I was asked to show that in the baryon octet, the $\Sigma^0$ baryon is the only particle which decays electromagnetically. Since it is an electromagnetic decay, strangeness should be conserved but I ...
1
vote
1answer
37 views

Quark Chirality Constraints in Nucleons

SW Engr here educating myself on particle physics, apologies in advance for any phrasing errors. I tried the google machine to no avail. Q: If only left handed matter fermions experience the weak ...
0
votes
0answers
38 views

Expanding isospin symmetry to $SU(3)$ flavor symmetry for Baryon octet diagram

Let's consider about the Baryon octet diagram. We can identify the isospin $I_3$ symmetry by noticing the mirror symmetry with respect to the $I_3$, i.e. x-axis. However, how can we expand this into $...
1
vote
2answers
67 views

Why aren't Delta and Omega particles stable?

Not only are they not stable their half-life is in the nanoseconds. Why are they so different from protons?
-1
votes
1answer
46 views

Why don't hadrons form from quarks of all the same charge?

Why don't Hadrons ever form from quarks of all the same charge? For instance you never see 2 or 3 up quarks together with no down quarks or vice-versa.
0
votes
1answer
37 views

Quark Model Families

I cannot understand what we mean when we say that we organise baryons and mesons in families. In other words, i have seen that a lot of books mention the baryon J=1/2 family. What do we mean by that? ...
0
votes
0answers
19 views

Quark Model Family

I have studied the baryon J=1/2 family.i did the $(Y,I_3) $ diagram and started from the highest weight $(\frac{1} {2} ,\frac{\sqrt{3} }{2}) $ which is the proton and used the operators $I_{+-} \ \ U_{...
2
votes
1answer
34 views

Why aren't hypernuclei based on lead-208 stable?

82 and 126 are magic numbers for nuclei, so $^{208}\mathrm{Pb}$ is doubly stable. So it seems to me like the hypernucleus $^{209}_{\Lambda^0}\mathrm{Pb}$ would be stable as well, because the $\Lambda^...
3
votes
1answer
89 views

How are quarks assigned color charge?

As always, I'll preface that I am wildly undereducated, so i may be overlooking something or be completely unaware of another relevant property. Color Confinement dictates that to "assemble" a baryon ...
14
votes
3answers
1k views

Are there any Baryons that have quark-antiquark combinations?

I'll be honest, I only have a Highschool education, so there might be something obvious I'm overlooking. However particle physics is of massive Interest to me. My question is, I know there are ...
35
votes
5answers
10k views

How do we know neutrons have no charge?

We observe that protons are positively charged, and that neutrons are strongly attracted to them, much as we would expect of oppositely charged particles. We then describe that attraction as non-...
3
votes
3answers
169 views

Why are primordial black holes considered non-baryonic? [duplicate]

A very important question that has been bugging me is why do people consider primordial black holes to be non-baryonic. I know that such a statement is then used to saying that they can be considered ...
3
votes
2answers
190 views

Physical significance of the decomposition $3\otimes\overline{3}=8\oplus 1$ in meson classification

Under the assumption of $SU(3)$ flavour symmetry of early days, proposed by Gell-Mann and Neeman, among other irreducible representations, the meson octet was obtained. This result from the $SU(3)$ ...
2
votes
1answer
141 views

Why is usual matter made up of $n,p$ and $e^-$?

We have six leptons and six quarks. Yet most of what we see around us is made of only neutrons, protons and electrons. For $\mu^-$ and $\tau^-$, I think the reason is that these are unstable particles ...
0
votes
1answer
65 views

What if there was no baryon-antibaryon asymmetry in our universe?

We know that the universe goes through different evolutionary phases: radiation, matter and later dark energy epoch. What would happen if there was no baryon-antibaryon asymmetry? How would the ...
0
votes
0answers
27 views

Does Hawking radiation violate baryon number conservation? [duplicate]

Throw two baryons into a black hole (baryon number +2), receive Hawking radiation out. Convert the resulting energy into one baryon and one anti-baryon (baryon number 0). Baryon number conservation ...
0
votes
0answers
36 views

The existence of Delta baryons was experimentally proven? [duplicate]

If we will look at the table from Wikipedia of their properties, we will find the same mass for all. That looks like a result of some calculation, rather then a result of measurement. Was that ...
1
vote
1answer
259 views

Why is baryon number conservation an accidental symmetry

I have to write a report surrounding the subject of baryogenesis and I wanted to start this report off with explaining how the first Sakharov condition: Baryon number violation is possible within the ...
1
vote
1answer
101 views

What is the systematic way to determine the spin of lowest-lying states of baryons like $uuu$, $ssd$, $uds$ etc?

I learned that for the lowest lying states, $uuu$, $sss$, $ddd$ can only have $J=\frac{3}{2}$ $uus$, $ddu$, $ddu$, $ssu$ etc can only have $J=\frac{1}{2},\frac{3}{2}$ $uds$ can have $J=\frac{1}{2}, \...
0
votes
1answer
64 views

Nuclei violating B number

Within SM, it is know that baryon number is not preserved and changes as $$ \Delta B = 3·\Delta n_{CS}, \quad n_{CS} \in \mathbb{Z}\ ({\rm Chern-Simons\ index\ for\ vacuum}) \tag1$$ Then, its ...
0
votes
0answers
43 views

B violation and electric charge

Within SM you can prove that despite we have baryon number conservation respect to Noether theorem, at quantum level baryon (and lepton) number is violated as $$ \Delta B = 3·\Delta n_{CS}, \quad n_{...
4
votes
1answer
186 views

What Does Up-Down Asymmetry Mean?

There is strong experimental evidence (reported on in the linked paper), from more than one high energy physics experiment, that up-down asymmetry is present in the decays of certain charmed baryons. ...
3
votes
2answers
3k views

Do we need dark matter and dark energy, if the behaviour of the universe in its initial stages was similar to that of the Sun? [closed]

According to CMBR the universe was a cloud of plasma and was a perfect black body, $380,\!000$ years after big bang. But the Sun in our solar system also is in the state of plasma, thus making it a ...
3
votes
1answer
158 views

Gluons pions and the strong nuclear force

Within Baryons is the force holding them together purely gluons or are pions involved? Between protons and neutrons in a nuclei is it purely the exchange of pions between baryons which hold the ...
1
vote
2answers
97 views

Why is a delta resonance decay not a radioactive decay

A delta resonance decays as given in http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/delta.html . I wonder, why is it not a radioactive decay? In principle, most/all decays should be radioactive ...
0
votes
2answers
63 views

Calculating the spin given the baryon wave function

This is probably a trivial question and I am missing something conceptually simple here. I have the spin part of the total wave function of a baryon consisting of three light quarks: \begin{equation}...
3
votes
1answer
173 views

Are black hole regarded as baryonic matter in cosmology?

Black holes do not have any property as baryonic or non-baryonic matter, as is stated by the no-hair theorem. Regarding conventional theories, in different models of cosmology, like Lambda-CDM, are ...
2
votes
0answers
111 views

Is there an experimental technique for specifically producing Delta minus baryons and clearly detecting the products of their decay?

Formerly I thought that Delta minus baryon was discovered in cosmic rays. However I was mistaken. Wikipedia says that Delta states were "established experimentally at the University of Chicago ...
9
votes
1answer
1k views

Is it a coincidence that quarks have exactly -1/3 or 2/3 the electron's charge? [duplicate]

I have read these questions: Why do quarks have a fractional charge? Is there an explanation for the 3:2:1 ratio between the electron, up and down quark electric charges? Hypercharge for $U(1)$ ...
-1
votes
1answer
24 views

Question about the spin of the antiparticle of $Δ^-$

Ι came across a statement in a physics book that the spin of the antiparticle of baryon $Δ^-$ is 1/2. I know that the spin for regular $Δ^-$ is 3/2, and - as far as I know - the spin of particles and ...
0
votes
0answers
52 views

What are the known ways to model baryons in string theory?

As I understand, string theory models baryons by including a so called "baryon vertex". Is this right? It seems that baryon vertex's are usually D/M branes. Is that always the case?
1
vote
3answers
107 views

Relativistic mass of components gives system rest mass?

To put it briefly, in the classic thought experiment of a massless box with mirrored insides containing photons, does the relativistic mass of the photons imbue the box with rest mass? I take it that'...
0
votes
1answer
135 views

Mass of mesons and baryons

In my introduction to nucleons and particles (basic) course, we were given the following formula to compute the mass of mesons and baryons : \begin{eqnarray} M(\text{meson}) & = & m_1 + m_2 ...