In
particle physics
Particle physics or high-energy physics is the study of Elementary particle, fundamental particles and fundamental interaction, forces that constitute matter and radiation. The field also studies combinations of elementary particles up to the s ...
, hexaquarks, alternatively known as sexaquarks,
are a large family of hypothetical
particle
In the physical sciences, a particle (or corpuscle in older texts) is a small localized object which can be described by several physical or chemical properties, such as volume, density, or mass.
They vary greatly in size or quantity, from s ...
s, each particle consisting of six
quark
A quark () is a type of elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nucleus, atomic nuclei ...
s or
antiquarks of any
flavours. Six constituent quarks in any of several combinations could yield a
colour charge of zero; for example a hexaquark might contain either six quarks, resembling two
baryon
In particle physics, a baryon is a type of composite particle, composite subatomic particle that contains an odd number of valence quarks, conventionally three. proton, Protons and neutron, neutrons are examples of baryons; because baryons are ...
s bound together (a dibaryon), or three quarks and three antiquarks.
Once formed, dibaryons are predicted to be fairly stable by the standards of particle physics.
A number of experiments have been suggested to detect dibaryon decays and interactions. In the 1990s, several candidate dibaryon decays were observed but they were not confirmed.
There is a theory that
strange particles such as
hyperons
and dibaryons
could form in the interior of a
neutron star
A neutron star is the gravitationally collapsed Stellar core, core of a massive supergiant star. It results from the supernova explosion of a stellar evolution#Massive star, massive star—combined with gravitational collapse—that compresses ...
, changing its mass–radius ratio in ways that might be detectable. Accordingly, measurements of neutron stars could set constraints on possible dibaryon properties.
A large fraction of the neutrons in a neutron star could turn into hyperons and merge into dibaryons during the early part of its collapse into a black hole . These dibaryons would very quickly dissolve into
quark–gluon plasma
Quark–gluon plasma (QGP or quark soup) is an interacting localized assembly of quarks and gluons at Thermodynamic equilibrium#Local and global equilibrium, thermal (local kinetic) and (close to) chemical (abundance) equilibrium. The word ''plasm ...
during the collapse, or go into some currently unknown
state of matter
In physics, a state of matter is one of the distinct forms in which matter can exist. Four states of matter are observable in everyday life: solid, liquid, gas, and Plasma (physics), plasma.
Different states are distinguished by the ways the ...
.
D-star hexaquark
In 2014, a potential dibaryon was detected at the
Jülich Research Center at about 2380 MeV. The center claimed that the measurements confirm results from 2011, via a more replicable method.
The particle existed for 10
−23 seconds and was named d*(2380).
This particle is hypothesized to consist of three
up and three
down quarks, and has been proposed as a candidate for
dark matter
In astronomy, dark matter is an invisible and hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gravity, gravitational effects that cannot be explained by general relat ...
.
The study found that production of stable d*(2380) hexaquarks could account for 85% of the Universe's dark matter.
H dibaryon
In 1977,
Robert Jaffe proposed that a possibly stable
H dibaryon with the
quark
A quark () is a type of elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nucleus, atomic nuclei ...
composition
udsuds could notionally result from the combination of two
uds hyperons.
Others
* In 2022 Riken researchers studied the existence of triply charmed dibaryon concluding computationally that it should fall within a feasible regime.
See also
*Deuteron
Deuterium (hydrogen-2, symbol H or D, also known as heavy hydrogen) is one of two Stable isotope ratio, stable isotopes of hydrogen; the other is protium, or hydrogen-1, H. The deuterium atomic nucleus, nucleus (deuteron) contains one proton and ...
, the only known stable composite particle that consists of six quarks.
* Dineutron, an unstable dibaryon.
* Diproton, another unstable dibaryon.
* Exotic hadron
*Pentaquark
A pentaquark is a human-made subatomic particle, consisting of four quarks and one antiquark bound together; they are not known to occur naturally, or exist outside of experiments specifically carried out to create them.
As quarks have a bar ...
References
{{particles
Hypothetical composite particles
Baryons