2021: a year physicists asked, 'What lies beyond the Standard Model?'

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The principal lecturer in physics and astronomy at the Rochester Institute of Technology.

If you ask a physicist like me to explain how the world works, my answer might be: "It follows the Standard Model."

The fundamental physics of the universe is explained in the Standard Model. It has traveled around the sun over 50 times despite the experimental physicists constantly looking for cracks in the model's foundations.

It has stood up to the scrutiny and passed all of the experimental test with flying colors. There are some conceptual gaps that suggest there is more to be learned about how the universe works.

The Standard Model has 17 fundamental particles and three of them are Neutrinos. They travel through the entire planet at all times of the day. I study the properties of particles.

Massive simulation of the universe probes mystery of ghostly neutrinos.

Physicists around the world ran a number of experiments in the year 2021. The teams measured the basic parameters of the model more precisely. The fringes of knowledge where the best experimental measurements don't match predictions were investigated by others. Groups built more powerful technologies to push the model to its limits and possibly discover new particles and fields. If these efforts succeed, they could lead to a complete theory of the universe in the future.

The Standard Model of physics allows scientists to make accurate predictions about how the world works, but it doesn't explain everything. The image is from the CERN.

Standard Model has filling holes.

The electron was discovered by J.J. Thomson using glass vacuum tubes and wires. New pieces of the Standard Model are being discovered by physicists.

The Standard Model does two things. It explains what the basic particles of matter are. The quarks that make up protons and neutrons are called electrons. It predicts how the matter particles interact with each other. The basic forces of nature are communicated by the bosons. After decades of work at the huge particle collider in Europe, the Higgs boson was discovered in 2012

The Standard Model is very good at predicting how the world works, but it has some holes.

It doesn't include a description of gravity. Physicists have not yet discovered a particle that conveys the force of gravity, despite Einstein's theory of General Relativity. Theory of Everything would do everything the Standard Model can, but also include the messenger particles that communicate how gravity interacts with other particles.

The Standard Model can't explain why a particle has a certain mass, physicists have to measure it directly. Physicists can only use these exact mass for predictions after they have been given them. The better the measurement, the better predictions can be made.

Physicists at CERN measured how strongly the Higgs boson feels. The mass of the Higgs boson was measured more precisely by another team. There was progress on measuring the mass of neutrinos. Physicists know that neutrinos have more than zero mass but less than the amount currently detected. A team in Germany is working on techniques that could allow them to measure the mass of neutrinos.

The Muon g-2 experiment shows discrepancies between experimental measurements and predictions of the Standard Model that point to problems in the physics. The image is from the Wikimedia Commons.

There are hints of new forces or particles.

The first measurement of the magnetic moment of the muon was made by members of the Muon g-2 experiment. The measurement of one of the muon's properties is the most accurate to date, and it is one of the fundamental particles in the Standard Model. The measurement didn't match the Standard Model prediction of the magnetic moment, which was the reason this experiment was important. Muons don't behave as they should. This could be a clue to undiscovered particles.

In April 2021, physicist Zoltan Fodor and his colleagues showed how they used a mathematical method to calculate the muon's magnetic moment. The predictions are different from the old ones and still work within the Standard Model.

Physicists will know if the experimental result is beyond the Standard Model if the new result and prediction are reconciled.

Physicists will be able to use new tools to search for dark matter. The image is from Mattia Di Mauro.

Physicists have to decide between creating mind-bending ideas about reality that make up theories and technology that can be tested in new experiments. It was a big year for the advancement of the experimental tools of physics.

The world's largest particle collider was shut down and underwent some improvements. The next data collection is planned to take place in May 2022. The power of the collider has been boosted so that it can produce a collision at 14 TeV, up from the previous limit of 13 TeV. The amount of energy carried by the batches of tiny protons that travel in beams around the circular accelerator is the same as that of a passenger train. Physicists may discover new particles that were too heavy to see at lower energies.

The search for dark matter was aided by technological improvements. Many astrophysicists believe that dark matter particles, which don't currently fit into the Standard Model, could answer some outstanding questions regarding the way gravity bends around stars, as well as the speed at which stars rotation in spiral galaxies. The Cryogenic Dark Matter Search has yet to find dark matter particles, but the teams are developing larger and more sensitive detectors to be deployed in the near future.

Hyper-Kamiokande and DUNE are two immense new detectors that are relevant to my work with neutrinos. Scientists will hopefully be able to answer questions about a fundamental asymmetry in the way neutrinos move. They will be used to watch for a phenomenon that is predicted to occur.

The Standard Model fails to explain every mystery of the universe. Physicists are using new technology to search for the Theory of Everything.

The Conversation's article is a Creative Commons licensed one. The original article can be found here.

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