Can hypernuclei with multiple strange quarks be formed and observed?

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Discussion Overview

The discussion revolves around the formation and observation of hypernuclei, particularly those containing multiple strange quarks, and the potential existence of hypernuclei with strangeness greater than three. Participants explore the properties of hyperons, the binding of hyperons to nucleons, and the conditions under which charmed and beautiful hypernuclei might form.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants inquire about the existence of hypernuclei with strangeness over three and whether any charming or beautiful hypernuclei have been observed.
  • There is a discussion on the definition of nuclei, emphasizing that they are made up of nucleons (protons and neutrons) and questioning whether hyperons can form bound states without nucleons.
  • Some participants mention that most hypernuclei studied contain only one Λ hyperon, with a few double hypernuclei observed through the conversion of Ξ hyperons into Λ particles.
  • There are questions about the binding of hyperons to each other and to nucleons via the strong force, and whether systems of hyperons without nucleons can be classified as nuclei or hypernuclei.
  • Concerns are raised about the rarity of forming nuclei with multiple baryons and the production of charm and beauty quarks, suggesting that these processes occur at different energy scales.
  • Participants discuss the implications of high-energy collisions, such as those at the LHC, on the production and binding of charmed and beautiful hyperons in hypernuclei.
  • There are inquiries about the fate of produced charm and beauty quarks in collisions and whether they can form bound states or are mostly annihilated or escape as free particles.
  • Some participants explore the possibility of converting ksions into Λ hyperons and the energy dynamics involved in such processes.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and properties of hypernuclei, the binding mechanisms of hyperons, and the feasibility of forming charmed and beautiful hypernuclei. The discussion remains unresolved with multiple competing perspectives on these topics.

Contextual Notes

There are limitations regarding the assumptions made about the binding of hyperons, the definitions of nuclei and hypernuclei, and the energy scales involved in the production of charm and beauty quarks. Some mathematical and physical claims are not fully resolved, and the discussion reflects ongoing exploration of these complex topics.

snorkack
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What are the strangest known nuclei? Specifically, have any nuclei with strangeness over 3 been seen?

Are there any known charming or beautiful hypernuclei? Considering that Be-8, with half-life 10-16 s is a well described nucleus, the 10-12...10-13 s lifetime of charming and beautiful hyperons should be plenty to form nuclei.

Also, have any nuclei been seen which contain no nucleons?

And what are the observed properties of neutral and negative hypernuclei?
 
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You seem to be confusing two different things. Strange and charm quarks are found in hadrons. Nuclei consist of protons and neutrons made up of up and down quarks.

Nuclei (by definition) are made up of nucleons.
 
mathman said:
Nuclei consist of protons and neutrons made up of up and down quarks.

Nuclei (by definition) are made up of nucleons.

Can hyperons be bound to nucleons by strong force, the way nucleons are bound to each other in nuclei?

Can hyperons be bound to each other by strong force?

What is a strong force bound system connecting of several hyperons but including no nucleons? Is it a nucleus or not?
 
Almost all hypernuclei studied contain just one Λ. Among the ones produced: 3ΛH, 4ΛH, 5ΛH, 6ΛH, 6ΛHe and 7ΛHe. There have been a few observations of double hypernuclei, which were formed after a conversion of a Ξ-hyperon into two Λ particles.

See this review paper.
 
Right - in presence of abundant nucleons of both tastes, hyperons can convert to lambda by quark exchange.

Note that baryons that differ by one quark cannot undergo quark exchange.

What happens when omegas are captured? In large nuclei, 3 lambdas, but in small nuclei?
 
snorkack said:
Can hyperons be bound to nucleons by strong force, the way nucleons are bound to each other in nuclei?

Can hyperons be bound to each other by strong force?
Right (both).
What is a strong force bound system connecting of several hyperons but including no nucleons? Is it a nucleus or not?
It is a hypernucleus, which is a subgroup of all nuclei.

The problem I see with charmed/beauty hypernuclei: both the formation of nuclei with multiple baryons and the production of charm/beauty-quarks are rare, and happen at different energy scales. The chance to have both at the same time could be low.
 
mfb said:
Right (both).
Hava any hypernuclei containing no nucleons been positively observed?
mfb said:
The problem I see with charmed/beauty hypernuclei: both the formation of nuclei with multiple baryons and the production of charm/beauty-quarks are rare, and happen at different energy scales.

Nuclei with multiple baryons are commonly present from the start. At high energy scales, they disintegrate, but is the energy equally distributed? The energy may be carried away mostly by a few baryons being some of the original nucleons, leaving the charmed or beautiful hyperons bound in a hypernucleus of some size.

There are 6 strange hyperons (without charm or beauty) and 2 nucleons. Between them, there are 14 pairs of baryons which differ by one quark and therefore cannot undergo quark exchange.
 
snorkack said:
Hava any hypernuclei containing no nucleons been positively observed?
That would be like a bunch of apples without apples. How is that supposed to look like?

Nuclei with multiple baryons are commonly present from the start.
What do you mean with "from the start"?

At high energy scales, they disintegrate, but is the energy equally distributed? The energy may be carried away mostly by a few baryons being some of the original nucleons, leaving the charmed or beautiful hyperons bound in a hypernucleus of some size.
Well, you need hard, inelastic scattering to produce charm or beauty quarks. A quark gluon plasma could be nice in that respect - it can slow down the heavy quarks. At the LHC, something like 50 ##c\bar{c}##- and 2 ##b\bar{b}##-pairs are produced (on average) per lead-lead-collision.
 
mfb said:
That would be like a bunch of apples without apples. How is that supposed to look like?
Imagine, say, aftermath of an omega capture:
Ω-+p->ksi0+lambda
ending up as a bound state.
If 2 (presumably different) hyperons but no nucleons are bound to each other by strong force in a way two nucleons are bound to each other in a deuteron, is the resulting bound system a "nucleus" or something else?
mfb said:
What do you mean with "from the start"?
Collisions where charm and beauty are formed often happen inside nuclei.
mfb said:
Well, you need hard, inelastic scattering to produce charm or beauty quarks. A quark gluon plasma could be nice in that respect - it can slow down the heavy quarks. At the LHC, something like 50 ##c\bar{c}##- and 2 ##b\bar{b}##-pairs are produced (on average) per lead-lead-collision.

And what comes in is 416 nucleons.

Where do these 50 charms on average wind up? How many on average fly away as mesons, how many depart as free charmed hyperons, and how many wind up bound in charmed hypernuclei?

Do all 416 nucleons (plus the extra nucleons formed in nucleon-antinucleon pairs) fly away as free nucleons, or do appreciable numbers of (presumably mostly small) nuclei form?
 
Last edited:
  • #10
snorkack said:
Imagine, say, aftermath of an omega capture:
Ω-+p->ksi0+lambda
ending up as a bound state.
If 2 (presumably different) hyperons but no nucleons are bound to each other by strong force in a way two nucleons are bound to each other in a deuteron, is the resulting bound system a "nucleus" or something else?
Ah, well, that depends on the interpretation of the word "nucleon" now. A bound state of several baryons without neutrons or protons is possible, but I don't know of observations of them.

Where do these 50 charms on average wind up? How many on average fly away as mesons, how many depart as free charmed hyperons, and how many wind up bound in charmed hypernuclei?
I am sure ALICE has published some papers about that. Some of them are annihilated before they form hadrons, some of them produce charmonium, some of them produce charmed hadrons, but I don't have numbers.

Do all 416 nucleons (plus the extra nucleons formed in nucleon-antinucleon pairs) fly away as free nucleons, or do appreciable numbers of (presumably mostly small) nuclei form?
Many protons and neutrons are destroyed in the collisions, and their valence quarks end up in other hadrons (several thousand particles are created in central collisions).
 
  • #11
Turns out that it is not exactly the baryons differing by 1 quark that are stable towards quark exchange.

Ksions can be turned into two lambdas. Like
ksi0(1315)+n(939)->2lambda(1116)+22MeV.
Note that the energy is small. But on the other hand, ksions cannot be turned into lambda plus sigma - to the contrary:
lambda(1116)+Ʃ+(1189)->ksi0(1315)+p(938)+52MeV.

Considering how small the energy production of ksion conversion is - can it be reversed by a suitable shell structure?
 

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