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 vote
1 answer
48 views

Finding $\Sigma$ wavefunctions from proton wavefunction. Any operator which can achieve this?

Knowing the isospin part of the wavefunction of the proton, it is possible to find that of the neutron by applying the isospin lowering operator $I_-$ which sits horizontally to the left of the proton ...
user avatar
2 votes
0 answers
79 views

Which force is responsible for $\Sigma$(1385) decay?

I was looking at the excited state of the $\Sigma^+$, the $\Sigma^{*+}(1385)$, on Wikipedia. I was wondering which forces are responsible for its two most dominant decays $$ \Sigma^{*+}(1385) \to \...
user avatar
  • 586
0 votes
0 answers
73 views

Spinor index contractions for baryons

For an $SU(N)$ QCD with $N_f$ flavours one writes baryons as \begin{equation} B^{{a_1}…a_{{N}_f}}=\epsilon^{i_1…i_N}\psi_{i_1}^{a_1}… \psi_{i_N}^{a_{Ν_f}} \end{equation} by contracting the colour ...
user avatar
  • 113
2 votes
0 answers
30 views

Could exotic baryons be stable inside exotic stars?

Neutrons are stable inside a neutron star because beta decay doesn't release enough energy to send the proton and electron up to the Fermi energy. Could this principle apply to baryons that have charm,...
user avatar
  • 734
0 votes
1 answer
102 views

What is the value of the baryon asymmetry? [duplicate]

Define the baryon asymmetry, which sometimes is called the baryon density, as the baryons to photons ratio $\eta = n_b/n_\gamma$. I found in Ref. 1, published in 2018, that the value of $\eta$ is of ...
user avatar
  • 89
1 vote
1 answer
59 views

About the recent bounds on the baryon asymmetry

While I'm studying the baryon asymmetry, the ratio of baryons number to the photons number in the universe - some times is called baryon density - $: \eta= n_b/n_\gamma$ I have found many experimental ...
user avatar
  • 89
0 votes
1 answer
75 views

Higgs decay into baryon-antibaryon pair

I have an exercise for "Introduction to high energy physics" and I'm baffled. The exercise states: Problem: Higgs particle of mass 125.7 GeV decays in an exclusive channel of baryon-...
user avatar
0 votes
1 answer
74 views

Mass of baryons and their spin state. Is there any connection?

Baryons are made of three quarks which are spin-1/2 particles. According to the rule of addition of angular momentum, baryons can have either spin-1/2 or spin-3/2. It is intriguing to note that light ...
user avatar
1 vote
1 answer
41 views

Nucleon resonance

I tried to fit low baryon resonances to N(1440) in an SU(3) octet. So I started with $$\frac{N + \Xi}{2} = \frac{3 \Lambda + \Sigma}{4}$$ What should the respective $\Lambda (I=0), \Xi(I=\frac{1}{2})...
user avatar
1 vote
1 answer
84 views

Gell-Mann—Okubo formula

How was the Gell-Mann—Okubo formula $$ M = a_0 + a_1 Y + a_2 \left[ I \left( I + 1 \right)-\frac{1}{4} Y^2 \right] $$ rewritten using isospin and strangeness to this formula? $$\frac{N + \Xi}{2} = \...
user avatar
0 votes
1 answer
142 views

Why can't $\Sigma$ baryons decay strongly?

First of all, I must say this is a homework question. The complete question includes particles like $p$, $e^-$, $\Lambda$ and $\Omega$. It's pretty easy to understand why $\Omega$ and $\Lambda$ have ...
user avatar
2 votes
1 answer
93 views

Why are Delta baryons called "Delta isobars"?

A lot of people seem to call the $\Delta$ baryon "Delta isobar", however there is no mention of "isobar" on its Wikipedia page. Am I missing something? Why do people use the term &...
user avatar
  • 2,323
0 votes
1 answer
255 views

Probabilities of $ \Omega^- $ baryon decay

The $ \Omega^- $-decay can occur in a few different ways. According to this document (page 3, $\Omega^−$ DECAY MODES), the three most probable decays are \begin{align} \Omega^- &\to \Lambda^0 + ...
user avatar
  • 26
4 votes
0 answers
107 views

’t Hooft anomaly matching and massless baryons

In Lectures on Gauge Theory by David Tong there is statement (section 5.6.3 The Vafa-Witten-Weingarten Theorems), that: To invoke the full power of ’t Hooft anomaly matching, we needed to assume that ...
user avatar
  • 5,291
0 votes
1 answer
55 views

Is it possible that rescuing the Idea of a Baryo/lepto-dynamic Field had some Relevance in the FermiLab Result?

We know that Fermilab, Brookhaven, and other laboratories have found discrepancies with the SM. One option that almost immediately comes to mind is that the so-far exact conservation law of baryon and ...
user avatar
  • 1,558
1 vote
2 answers
126 views

Baryon to photon ratio

In Dodelson's "Modern Cosmology", the current baryon-to-photon ratio is defined as $$ \eta_b \equiv \dfrac{n_b}{n_\gamma} = 5.5 \times 10^{-10} \left(\dfrac{\Omega_b h^2}{0.020}\right). $$ I ...
user avatar
  • 329
8 votes
1 answer
696 views

What fraction of the mass of all baryonic matter are black holes?

Is there a calculation of how much of the mass of baryonic matter is black holes, including supermassive black holes in the center of galaxies?
user avatar
-1 votes
3 answers
74 views

Like quark baryons

Why aren't there particles like neutrons or protons but with 3 up or 3 down quarks, instead of 2 up/1 down or 2 down/1 up. Does there have to be 2 different types of quarks for the strong force to ...
user avatar
0 votes
1 answer
179 views

How does the process $\bar{K}^0+p \to \Lambda^0+\pi^+$ work?

I was asked to find an energy for the $\bar{K}^0+p \to \Lambda^0+\pi^+$ interaction for an exercise and I got curious about how the Feynman diagram for this process would look like. In terms of quarks,...
user avatar
  • 3
1 vote
1 answer
49 views

Is the process $\pi^{-}+p^+\to\bar{n}+n+n $ allowed?

Is the process $\pi^{-}+p^+\to\bar{n}+n+n $ allowed? Is there any collision involving only the mesons and baryons that would produce antibaryons (along with other particles)?
user avatar
2 votes
1 answer
36 views

What happens to extra-galactic rays when they arrive at the solar system?

Quazars send baryons from other galaxies towards us which are deflected from by the local magnetosphere. The early solar system probably picked up many millions of extragalactic cosmic rays for every ...
user avatar
0 votes
1 answer
34 views

Is the baryon number consistent when it comes to annihilation?

I've previously asked a question on here about if it was possible to change the barion number by radioactive decay, for example positron emission, and the answer was of course no, as the baryon number ...
user avatar
  • 301
2 votes
1 answer
129 views

Could a Λ or Σ baryon be stable inside a nucleus?

A common "cartoon model" of a nucleus is that there are a set of bound energy levels for the protons and a similar set of bound energy levels for the neutrons. The existence of these energy ...
user avatar
4 votes
1 answer
408 views

Can protons and neutrons be completely converted into Leptons?

In beta decay, a neutron releases an electron and turns into a proton. The inverse happens, though usually not naturally, in positron emission, where a proton emits a positron and becomes a neutron. ...
user avatar
  • 301
-2 votes
2 answers
138 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 $\...
user avatar
0 votes
0 answers
16 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...
user avatar
  • 3,443
0 votes
1 answer
117 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 ...
user avatar
1 vote
0 answers
65 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 ...
user avatar
  • 419
0 votes
0 answers
61 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 ...
user avatar
0 votes
0 answers
39 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 ...
user avatar
5 votes
1 answer
317 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 ...
user avatar
  • 732
3 votes
1 answer
141 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....
user avatar
  • 732
1 vote
1 answer
37 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 "...
user avatar
0 votes
1 answer
119 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 $$...
user avatar
  • 4,070
7 votes
1 answer
114 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 ...
user avatar
  • 81
6 votes
0 answers
99 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 ...
user avatar
4 votes
0 answers
89 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 ...
user avatar
  • 5,291
0 votes
1 answer
31 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?
user avatar
3 votes
1 answer
162 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}\...
user avatar
  • 5,291
1 vote
2 answers
108 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, ...
user avatar
  • 5,291
0 votes
1 answer
42 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 ...
3 votes
1 answer
492 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 ...
user avatar
1 vote
1 answer
80 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 ...
user avatar
  • 13
0 votes
0 answers
52 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 $...
user avatar
  • 511
1 vote
2 answers
144 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?
user avatar
-1 votes
1 answer
52 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.
user avatar
0 votes
1 answer
42 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? ...
user avatar
0 votes
0 answers
28 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_{...
user avatar
3 votes
1 answer
84 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^...
user avatar
  • 173
3 votes
1 answer
280 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 ...
user avatar
  • 351