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cosurgi [soylentnews.org] writes:

More precision measurements are planned at LHC [1]. Short extract below:

When ATLAS and CMS discovered the Higgs boson [2] and confirmed the validity of the Brout-Englert-Higgs mechanism, physicists were hungry for more. But the Higgs was a giant tree hiding a meadow full of well-known flowers. No exotic plants were to be found in these high-energy plains. Month after month, the Standard Model has revealed itself to be more solid than ever. Previously when higher energy at LHC was possible scientists were looking for spectacular phenomena that have now mostly been ruled out. The approach now is to carry out precision measurements.

In reality, the Standard Model is built on two quantum theories : the electroweak theory [3], which describes the electromagnetic and the weak forces, and quantum chromodynamics, which describes the strong force. So, here we have the basics. One advantage of the Standard Model is that it is predictive: it predicts all possible interactions between particles with a precise probability (which physicists call the “cross section”). However, it doesn’t predict the masses of the fundamental particles: these are among the parameters measured by the experiments. These masses vary greatly e.g. the heaviest top quark, is almost 90 000 heavier than the up quark, the lightest. In total, there are 19 free parameters which determine the inner workings of the standard model (aside from the parameters relating to neutrinos). Measuring them precisely is crucial to be able to calculate the interaction cross sections and test the consistency of the Standard Model. Although the Standard Model doesn’t predict their values, it ties some parameters together. "By [more precisely] measuring all of these parameters independently, we test the relationships predicted by the Standard Model and impose constraints on physics beyond the Standard Model." explains Andrew Pilkington, a physicist with the ATLAS experiment.

One of the success stories of the LHC is how it has improved the measurements of these free parameters, starting, of course, by determining the mass of the Higgs boson [4]. ATLAS has also increased the precision of the mass of the W boson [5]. “This was a remarkable achievement that no one had anticipated,” says Jonathan Butterworth, a physicist with the ATLAS experiment who was co-leader of the Standard Model group in 2010. Also the precise measurement of the electroweak mixing angle is one of the key results from the LHC experiments. This result serves to constrain the masses of the W and Z bosons.

The LHCb experiment [6] studies B hadrons (the particles containing a bottom or anti-bottom quark) and provides very high precision data used to determine the probability that a quark will transform into another via the weak interaction. These transformation processes were first described by Nicola Cabibbo, Makoto Kobayashi and Toshihide Maskawa - the CKM matrix, which is made of four free parameters. The structure of the CKM matrix can be represented graphically by triangles, with the parameters represented by the lengths of the sides and the angles. For example, LHCb has obtained the best measurement of one of these angles, γ [7]. This work is linked to work on the phenomenon of charge-parity (CP) violation, which is at the origin of a difference in behaviour between matter and antimatter. The experiment has also obtained excellent results relating to CP violation, including proof of the phenomenon occurring with particles containing a charm quark [8], whereas before it had been observed only with particles containing a strange or a bottom quark. “The LHCb programme has evolved not only to confirm CP violation with B mesons, but also to understand the phenomena of flavour physics in general,” explains Tatsuya Nakada,“The study of these phenomena is an extremely useful way of measuring the coherence of the Standard Model.” LHCb experiment has become a gold standard in the field of flavour physics, achieving crucial results studies of the weak interaction, and in the field of CP violation.

“Precision is a fantastic tool for understanding the world of particles,” says Gian Giudice, head of CERN’s Theory department. “The LHC has moved from discovery to precision and there is lots to learn.”

submitter's note: I guess that if we had a hardon collider built on the Moon, we might get different values for some of the 19 free parameters.

[1] https://home.cern/news/series/lhc-physics-ten/welcome-precision-era [home.cern]
[2] https://home.cern/news/series/lhc-physics-ten/higgs-boson-what-makes-it-special [home.cern]
[3] https://home.cern/science/physics/unified-forces [home.cern]
[4] https://home.cern/news/series/lhc-physics-ten/higgs-boson-revealing-natures-secrets [home.cern]
[5] https://home.cern/news/news/first-high-precision-lhc-measurement-w-boson-mass [home.cern]
[6] https://home.cern/science/experiments/lhcb [home.cern]
[7] https://lhcb-public.web.cern.ch/Welcome.html#gamma [web.cern.ch]
[8] https://home.cern/news/press-release/physics/lhcb-sees-new-flavour-matter-antimatter-asymmetry [home.cern]

Original Submission