* It is worth recalling that even the best telescopes often aren't very precise.
For example, the state of the art precision with which we can measure the distance from Earth to the reasonably close M87 galaxy is about ± 2-3%.
* By comparison, in high energy physics, scientists have recently detected a rare form of decay predicted by the Standard Model of Particle Physics at that frequency, from a three valence quark particle with two valence up quarks and one valence strange quark that is about 27% more massive than a proton, known as a sigma plus baryon, which accounts for just one in 100 million decays of this kind of particle, which is a tiny effect (although admittedly, the precision of that measurement is just ± 16%).
The most recent theoretical predictions for the branching fraction B(Σ+ → pµ+µ−) lie within the range [1.2, 7.8] × 10^−8. The experimentally measured value is [0.81, 1.25] × 10^−8 derived from 237 ± 16 observed decays of sigma plus baryons to a proton, a muon, and an anti-muon.
This is the smallest baryon decay branching fraction ever definitively observed, and implicitly rules out all manner of even very slight deviations from the Standard Model of Particle Physics at the ten parts per billion level in the processes that are involved in this decay.
This branching fraction measurement took a data set of about 24 billion sigma plus baryon decays, which themselves are created in only a small fraction of the many trillions of Large Hadron Collider (LHC) particle collision events that scientists at CERN have observed to date.
* As another example, another recent paper makes a first principles calculation using lattice QCD of the absolute frequency of a certain kind of particle decay (without reference to the frequency of other possible decays of that particle), using standard world averages for the physical constants involved, and compares this prediction to two experimental measurements of the frequency of that particle decay and their average value, producing the following results:
The difference between the predicted frequency and each of the two experimentally measured frequency (as well as their average value) are within one standard deviation of each other, as are the experimentally measured frequencies with each other. This is, of course, what scientific theories and experiments are suppose to do.
* In contrast, calculations made using only the electromagnetic part of the Standard Model of Particle Physics (quantum electrodynamics or QED for short) and the weak force, without implicating quantum chromodynamics (QCD), which is the physics of the strong force, and without implicating neutrino oscillations, are many orders of magnitude more precise.
* While it is not precisely on topic in this post, another article today looks at the subtle differences between a single bound state of more than three valence quarks into a composite particle known as a hadron, and a "hadron molecule" that is made up of two composite particles with two or three valence quarks each, bound to each other in a manner analogous to the way that protons and neutrons in an atomic nucleus are bound to each other, at a theoretical level.
* Finally, a new paper examines a way of approximating QCD calculations for hadrons by assigning a rest mass of 450 MeV/c^2 to gluons (which is about half the mass of a proton), rather than following the Standard Model assumption that gluons are massless, and gets some promising results.
This is, however, simply a calculation trick. We know this because pions, which are composed of light quarks bound by gluons, have a mass of less than 450 MeV.
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