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".

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124 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 $SU(3)$ ...
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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 ...
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Where/How can I find the wavefunctions of Excited Baryons/Nucleons

For example: the $P11(1440)$ resonance and the $S11(1535)$ resonance each have a total angular momentum $J = \frac{1}{2}$. How would I go about finding the Spin-Flavor wavefunctions of these and many ...
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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 ...
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Resources on Physical Baryon States as mixings of multiplet states

I've been told, and have seen in papers (search for "mixing") that baryon resonances are not plucked from pure group theoretic multiplets, but are most often found to be mixings of states in different ...
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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 ...
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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 ...
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65 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 ...
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65 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}, \...
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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 ...
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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_{...
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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. ...
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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 ...
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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 ...
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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 ...
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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}...
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Why do we assume that there had to be a baryon-antibaryon-symmetry in the first place?

Maybe this is obvious to some, however I have not found a satisfying answer yet. Detailed answers appreciated!
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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 ...
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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 ...
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995 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 $U(1)$ ...
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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 ...
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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?
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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'...
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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 ...
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Basic question on spin wavefunction

In my textbook, I am told that the $\Delta$ is a spin-3/2 particle made up of three spin-1/2 quarks. For a state with definite spin $m=-1/2$, I'm given that the spin wavefunction $$\dfrac{1}{\sqrt{3}}(...
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About the asymmetry of baryons

I don't understand why CP violation is insufficient to explain the observed baryon asymmetry? And how do you solve it using the lepton sector? Key Words: CKM - Cabibbo-Kobayashi-Maskawa Matrix: in ...
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Space and spin symmetry in light baryons

In Particle Physics by Martin and Shaw in Ch.6 they show how the baryon supermultiplets are built from the assumption that the space and spin wave functions are symmetrical, so eg. $uud$ has spins up,...
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Number of baryons in the Skyrme model

In QCD, the Eightfold Way organizes the number of baryons with respect to their flavor and color quantum numbers: for three light $(u,d,s)$ quark constituents, a spin-(1/2) baryon octet and a spin-(3/...
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Why heavy bosons are unstable?

I'm​ working with dark matter and in the some of concepts is that shall exist WIMPs (weakly interacting massive particles) in which are made by baryons... However, we know that this cannot satisfy the ...
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Why is there not enough CP violation to account for baryogenesis in the SM?

One of Sakharov conditions states that both C and CP symmetries must be violated by a theory which includes any baryogenesis mechanism. The Standard Model happens to be such a theory, and happens to ...
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702 views

Why is the proton the only stable hadron?

The title pretty much explains the question, but I've always thought that it'd be a neutron because of its 0 charge.
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Identifying the flavour singlet baryon

I would like to ask how to identify the lowest lying flavour-singlet baryon in the data on known states of particles. So far I managed to derive the following constraints: Its quark content must be $...
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Can an anti-hydrogen atom decay into a hydrogen atom?

I was thinking about Baryon asymmetry just to mess around with ideas and thought about this. Could it be that all the anti-matter decayed into matter?
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Difference between particle and state

I have recently started studying particle physics, and I was surprised by the description of hadrons. At first I was told that the $\Delta^0$ baryon was composed by one up and two down quarks, and ...
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1answer
166 views

If Baryons are subject to the strong nuclear force, how are they involved in Beta decay?

The question is really in the title with this one, I just need a little bit of clarity, consider beta-minus decay, which is an interaction governed by the weak nuclear force, $$n\to p^+ +e^- +\bar v_e$...
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Density of baryons

I wanted to recalculate the number of atoms in the universe according to What paper can I cite for the estimated number of atoms in the observable universe to be lower than $10^{82}$? . But in the ...
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213 views

Why does the $\Lambda^0$ exist?

In looking at the particle charts I see 3 Sigma baryons with very similar masses and other similar properties, which makes sense since they all have one strange quark plus two others from the (up,down)...
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Why do we antisymmetrize the baryon's wavefunction but not the meson's?

A many-body wavefunction of identical fermions must be antisymmetrized because of fermionic statistics. We don’t antisymmetrize the meson wavefunction because it contains a quark and an antiquark, and ...
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How could we determine the color of a black hole's hair?

It was once thought that black holes were characterized by their mass, charge, and angular momentum. This was known as the no-hair conjecture. More recent work on black hole physics (see here) ...
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$SU(3)_F$ flavour symmetry and $SU(2)$ isospin symmetry

There is an approximate $SU(3)_F$ flavour symmetry that exists at the quark level between $u$, $d$ and $s$ quarks. But we often talk about an approximate isospin $SU(2)$ between up and down quark only?...
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Which came first: leptons or baryons?

If you had a big collection of neutrons, they could decay into protons, electrons, and neutrinos through beta decay since protons are the only stable baryons. After a while, you should get hydrogen ...
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What is the ratio of gluons to baryons?

Gluons bond quarks into baryons (i.e., protons and neutrons). For example, two up quarks and one down quark form a proton while one up quark and two down quarks form a neutron. Is there one gluon per ...
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461 views

How to Derive Baryon Octet Matrix?

In every textbook on particle physics that I've read, I encounter the following matrix when reading about matrix of wave functions for the baryon octet: $$\left[\begin{array}{ccc} \frac{\Sigma^0}{\...
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Confusion in proton decay

I read that a proton cannot decay because it is the least massive baryon. However, in positron emission, the proton converts to a neutron a releases a positron. Is that considered a proton decay?
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Is the neutron its own antiparticle? [duplicate]

I have seen multiple claims that the neutron is its own antiparticle. However surely the antiparticle of the neutron would have a baryon number of -1 because it would consist of three antiquarks, each ...
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155 views

$\Omega^0_c \to \Sigma^+ K^-K^- \pi^+$ Feynman diagram

How can I work out the Feynman diagram for the decay process, $\Omega^0_c \to \Sigma^+ K^-K^- \pi^+$?
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559 views

$\Sigma^{+}$ baryon decay- why no decays to neutron and electron-neutrino pair?

I am working on a homework problem involving a decay of the form $\Sigma^+\rightarrow n+e^++\nu_e$, with the goal of providing justification for why this decay is not experimentally observed. To ...
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How can we explain that $\Sigma \pm$ have different masses whereas K$\pm$ have the same mass?

I guess it is because of the forces between the quarks inside them but I am not quite sure how to explain it.
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Is it true that neutrinos are billions of times more than all baryonic matter and electrons?

Here, it mentions that the total number of electrons in the observable universe is around 10^80, while this states that the total number of baryons are again, ...
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Why do we have only 4 SU(2) total spin and isospin 3/2 baryons?

In the context of SU(2), we find that for a quark triplet $qqq$ there are 4 wavefunctions of total Isospin $3/2$, ranging for $I_3$ going from $-3/2$ to $3/2$. Furthermore, these wavefunctions are ...