New evidence from LHC shows pentaquark has a molecule-like structure

New evidence from LHC shows pentaquark has a molecule-like structure
Credit: APS/Carin Cain

A team of researchers working on the LHCb collaboration has found evidence showing that a pentaquark they have observed has a molecule-like structure. In their paper published in the journal Physical Review Letters, the group describes the evidence and the structure of the pentaquark they observed.

Four years ago, a team working at the Large Hadron Collider (LHC) observed what is known as a pentaquark by smashing protons into each other. Its existence had been theorized, but it was not until the right technology was deployed at the LHC that researchers were able to observe it with a reasonable degree of confidence. It was subsequently found to be a particle made up of four and one antiquark. (Quarks are indivisible particles that make up neutrons and protons.)

In this new effort, the researchers have gained a better perspective on the actual organization of the pentaquark. They report that they have nine times as much data from observations as they had when the pentaquark was first observed, so they have high confidence in their findings. They report that the pentaquark was made up of a three-quark baryon and a quark-antiquark meson, and that they were bound together in a way reminiscent of a molecule.

More specifically, they found that the pentaquark was made up of different "flavors" of quarks—two up quarks, one down quark, one charm quark, and finally, a single anti-charm quark. They further report that they do not know what was the driving factor that led to the arrangement of its components. They also noted that the initial observation of the pentaquark three years ago was actually an observation of two pentaquarks that were nearly identical.

The researchers also report that their observations were the first ever to see baryons and mesons sticking together—until now, baryons have only been observed sticking to other baryons. They also acknowledge that it is conceivable that not all pentaquarks have the same molecular-type structure that they observed, noting that theory suggests it is possible for them to have other types, including split-second interactions. They hope more research will contribute to further understanding of the pentaquark and its characteristics.


Explore further

CERN's LHCb experiment reports observation of exotic pentaquark particles

More information: R. Aaij et al. Observation of a Narrow Pentaquark State, Pc(4312)+ , and of the Two-Peak Structure of the Pc(4450)+, Physical Review Letters (2019). DOI: 10.1103/PhysRevLett.122.222001 , https://arxiv.org/pdf/1904.03947.pdf
Journal information: Physical Review Letters

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Citation: New evidence from LHC shows pentaquark has a molecule-like structure (2019, June 7) retrieved 17 June 2019 from https://phys.org/news/2019-06-evidence-lhc-pentaquark-molecule-like.html
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Jun 07, 2019
Well that is interesting.

Jun 07, 2019
Interesting... and it seems to make some sense, in a fractal sort o way...

Jun 07, 2019
We've only just started on this.

Jun 07, 2019
any predictions?

my guesstimate is that the term "molecular-kinda-like structure" maybe applicable to other phenomena.

Seeing patterns, real or projected? Such as looking down, from a height, at a prairie of wind-blown grasses or sandy desert or open lakes or ocean.

Are you looking at the trees or the forest?

Jun 07, 2019
Bob Yirka
The researchers also report
That their observations
Were the first ever to see
Baryons and mesons sticking together

Mesons
Are intermediate mass particles
Which are made up of
A quark-antiquark pair

Baryons
While the baryons are fermions

Fermions
In particle physics
A Fermion is a particle
That follows Fermi–Dirac statistics
These particles
Obey the Pauli Exclusion Principle
Fermions include all quarks and leptons
As well as all composite particles
Made of an odd number of these
Such as all baryons and many atoms and nuclei

A Fermion can be an elementary particle
Such as the electron
Or it can be a composite particle
Such as the proton

The Pauli Exclusion Principle
Is the quantum mechanical principle
Which states that two or more
Identical fermions particles
With half-integer spin
Cannot occupy the same quantum state
Within a quantum system simultaneously

As this witching circle continues its destination
This Pauli Exclusion Principle
Comes full circle

Jun 07, 2019
So as this Witching Circle Continues

Baryons and mesons sticking together
While the baryons are fermions
Where fermions are electrons

Where electrons are indivisible particles

The object of this experiment
Concerns quarks
Quarks are indivisible particles
That only exist in protons
Making a proton a composite particle
Forming molecules

As this witching circle continues its destination
This Pauli Exclusion Principle
Comes full circle
this witchery comes full circle
Where this Pauli Exclusion Principle
Blurs this distinction
Between composite particles
And indivisible particles
As if we assume
Quarks actually exists as indivisible particles

Protons, are then composite particle

Electrons are indivisible particles

Quarks are indivisible particle

This Pauli Exclusion Principle
When you follow sub meaning to subsequent meaning
As always
With this Pauli Exclusion Principle
Eventually
Come back to whence you started
This Exclusion Principle
Full circle back to where you started

Jun 07, 2019
Atoms and molecules... so simplistic, so passe. Just what could we make out of subatomic molecules or exotic particles we havent even discovered yet? Supersymmetry matter? Antimatter matter? Compounds using stuff from the island of stability perhaps?

Jun 07, 2019
Could be why we're so interested in magnetic bottles and atom smashers; not for power but for production and storage of potential new materials which must be kept in plasma form during synthesis...

Jun 07, 2019
"but for production and storage of potential new materials which must be kept in plasma form during synthesis."

Isn't that processing called "Glasma"?

Wake me up....
When we get down
to the
Planck foundational gravitrons.

Jun 07, 2019
WTF are ever talking about you loon? Dont you want to have a rational conversation? Afraid of finding out how pedestrian you are?

Jun 09, 2019
So predictable based on e.g. a tight interlocking loop model. If this surprises anyone in the quark business they should really hang it up.

Jun 09, 2019
We've only just started on this.


Yes. It sounded to me like they found a proton/meson hydrogen analog (duu)(cc_), but the paper seems to say a charmed sigma as the baryon (duc)(c_u). Lots of uncertainties in there how this even works, even if they *do* seem to see the two state's peaks.

Jun 10, 2019
In 2015 the team analyzed data from the decay of the Λb particle, which consists of three quarks, into three quark-containing particles: a J∕ψ, a proton, and a charged kaon. They found that sometimes, when Λb decays, it turns into an intermediate state comprising a five-quark particle and a kaon. But despite having a whopping statistical significance of 9σ, the result relied on model assumptions about the nature of other intermediate states containing a kaon and a proton. Once again the result relied on model assumptions.

Jun 10, 2019
Stop! Please stop! You are making fools of PhDs. None of this has The Formal Logic as its basis. Really, guys? You are out of bounds from good sense. Nonsense is without logic. Check your self. You don't want to be remembered as The Idiots of the 21st century, do you?

Jun 10, 2019
Sorry to me a pentaquark must be one object, not a baryon and meson, because surely the proton in this case was very high energy and emit a photon which split into the charm anti-charm meson.

Surely this only proves the strong force wont allow free quarks, and created the meson rather than break the proton apart. Which if I am not mistaken is just QCD, nothing new.

Now if the pentaquark had 5 quarks, no antiquarks. That could prove there can exist more than 3 colours, that would be special, just not sure how we could measure such an event is 3D space as 5 colours would imply 5D space surely.

Jun 10, 2019
WTF are ever talking about you loon? Dont you want to have a rational conversation? Afraid of finding out how pedestrian you are?


I get your bewilderment, and even frustration, toward wacky comments; however that last sentence pretty much sums up why every anti-intellectual and anti-science, anti-evidence based individual is against everything you hold dear. Not because they disagree with you, most people including me don't have enough education in the sciences to have an even have an opinion, but because they don't like being condescended to. Let's try not be jerks to people.

Also whats the beef with a pedestrian? Walking is good for you, in the right doses.

Jun 10, 2019
Get the wrong thread, @Turing?

Jun 10, 2019
How do the quark and anti-quark in the meson stick together and don't annihilate each other ??

Jun 10, 2019
If you supposed having multiple independent spin axes sharing a single point is somehow better than only one, then you supposed the pentaquark was a baryon bound to a meson.

Jun 10, 2019
How do the quark and anti-quark in the meson stick together and don't annihilate each other ??
They're different flavors and/or different colors.

Jun 11, 2019
How do the quark and anti-quark in the meson stick together and don't annihilate each other ??
They're different flavors and/or different colors.


An interesting thought is based on the math foundations of loop inverse estimation in unified matrix and tensor (array) calculus with past applications in many problems of digital and analytic photogrammetry and geodesy. The physics and math communities appear unaware of this work in my academic studies in Finland, Sweden and US since late 1960's. After my 2004 retirement from industrial work in satellite photogrammetry and GPS I expanded my private studies and recent PO etc blogs to learn and explain some new unified physics concepts of Suntola Dynamic Universe (DU). The same 'epicycle' principle to explain the flaws of SR/GR/QM/String etc. theories in terms of DU may also apply to the multiplicative meson product of quark and its anti-quark (cont).

Jun 11, 2019
Pedestrian adj
"lacking inspiration or excitement; dull.
"disenchantment with their present, pedestrian lives"
synonyms: dull, plodding, boring, tedious, monotonous, uneventful, unremarkable, tiresome, wearisome, uninspired, uncreative, unimaginative, unexciting, uninteresting, lifeless, dry" ...ordinary

-People who use useless annoying affectations like mr Keats and his poetry.

Jun 11, 2019
In the special case of Einstein era in tensor calculus (he learned it from Levi-Civita) a full rank regular square n,n matrix A and it 'anti' or inverse-matrix annihilate each other. A full-rank m,n matrix A has l.s or L-inverse G=(A*A)^-1 A* that minimizes the sum of squares of residuals of m observed values L and provides BLUE X=GL for modeling parameters of X in A X=L+V. Many problems in math physics are singular or rank-deficient r(A)

Jun 11, 2019
The entire set of solution space for rank-deficient system r(A) may explain the pentaquark structure but cannot be detailed here.

Jun 11, 2019
It suffices to point out the main flaw of SR,QR,QM in postulate of constant observable c_obs in Earth ECI energy frame. Matrix A special case of a scalar is found by multiplying the local observable speed c_obs=f(C4) by factor k. C4 is the decelerating expansion speed of 4-radius R4 by a factor k to get the instantaneous reduced speed k c_obs using modern physical atomic clock. Its ticking rate due to DU energy balance is reduced by the same factor or k c_obs/k = c_obs=constant. To model SN1a emitted energy/quanta you have to use the (1+z) times higher value of C4_emittal few B yrs ago vs today's C4_receival. And you must correct the distorted distance/time concepts of GR or introduce auxiliary parameters of DE/DM densities to compensate the systematic error of GR 'trend function' - a repeat of Earth vs Sun centered epicycle mistake 400 - 500 yrs ago! Today rewarded by 2011 Nobel for detection of DE.... and then 2017 GW 'proof'....

Jun 12, 2019
the main flaw of SR,QR,QM in postulate of constant observable c_obs in Earth ECI energy frame. Matrix A special case of a scalar is found by multiplying the local observable speed c_obs=f(C4) by factor k. C4 is the decelerating expansion speed of 4-radius R4 by a factor k to get the instantaneous reduced speed k c_obs using modern physical atomic clock. Its ticking rate due to DU energy balance is reduced by the same factor or k c_obs/k = c_obs=constant. To model SN1a emitted energy/quanta you have to use the (1+z) times higher value of C4_emittal few B yrs ago vs today's C4_receival. And you must correct the distorted distance/time concepts of GR or introduce auxiliary parameters of DE/DM densities to compensate the systematic error of GR 'trend function' - a repeat of Earth vs Sun centered epicycle mistake 400 - 500 yrs ago! Today rewarded by 2011 Nobel for detection of DE.... and then 2017 GW 'proof'....
Is this real or like the sokal hoax? More poetry perhaps?

Jun 12, 2019
I was going to suggest trying the sweet and sour orange soup for poetic relief.

Jun 13, 2019
I was going to suggest updating the 2-loop Lm-inverse solution of meson/anti-meson pair with the extra constraint equation of 5-D DU energy balance constraint of three boson quarks using the 3-loop mLm-inverse in the fashion of Nordstrom 'extra dimension' or sequential condition adjustment of Maxwell equations. But its math of loop inverses is far more complicated than summarizing the biggest 'epicycle' mistake of SR, GR and QM of DU physics foundations in the cosmic vs quantum micro scale. And I don't want to insult additional past Nobel committees as the recent mistakes of DE and GW 'proofs' already suffice in the cosmic scale...who could be the 3rd one to understand Suntola DU? Perhaps Sir Eddington and his 'faster than thought GW'...

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