Event

17:35
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18:15

Day 3

High energy physics aside the Large Hadron Collider

Recorded

Science

What are we, and where do we come from? - Searching for flavour in beauty Nowadays the Large Hadron Collider (LHC) at CERN is the best known high energy physics research facility. However, there are other facilities around the world performing cutting edge high energy physics research. Some of these are the so called flavour factories which have a long tradition in high energy physics. Two of these are currently in operation: BES III in China and Belle II in Japan. Collecting huge amounts of data, the goal of these experiments is to measure free parameters of the standard model of particle physics with very high precision to find deviations from predictions by theory. Such deviations can hint to new physics, and physicists are still searching for the reasons of our very existence as by our best knowledge nothing but light should have remained after the big bang. But testing the standard model is challenging. Huge data sets in the order of tera bytes need to be analysed requiring advanced analysis software and techniques. By now these analyses usually employ machine learning and artificial intelligence in various kinds, while using custom hardware and software, and a world spanning computing infrastructure. All of this is only possible with more than 1000 people working together in a collaboration. Part of the work in high energy physics nowadays would not be possible anymore without the groundbreaking research by this year's Nobel laureates for physics. In this talk I will present what flavour physics is, the reasons why flavour physics is interesting and why it matters, and which challenges we are facing, using the Belle II experiment as an example. Most of the challenges are not unique to Belle II but to high energy physics in general, so I will also set this into the bigger context and take a look to what is ahead of us in the field of high energy physics.

Developed in the 1950s to 1960s, the standard model of particle physics has been a huge success. However, there are parts it cannot describe:

During the big bang the same amount of matter and anti-matter should have been produced, and they should have annihilated only leaving light. But here we are, so there must have been some sort of imbalance or asymmetry. With our current understanding of particle physics and the big bang we cannot explain the amount of asymmetry necessary to explain our existence. So why are we here?
We found that neutrinos do have mass, while the SM predicts them to be massless. So why do neutrinos have mass and where does it come from?
The orbital velocities of stars in distant galaxies show deviations from expectations if only visible matter is taken into account. These deviations in the galaxy rotational curves hints to additional matter which nowadays we call "dark matter". But what is its origin
The universe seems to expand with an increasing rate, but what is the driver behind this rate? We now describe this as "dark energy" but do not really know what it is made of.
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Cosmology, astrophysics, and high energy physics are working on solving these mysteries. While the first two require observations of space and simulations on earth, the last one can be fully conducted on earth. In high energy physics we currently are following to paths of finding physics beyond our current understanding called the "standard model" of particle physics: direct and indirect discoveries. This can be achieved by testing ever higher energies, or by probing known processes with improved precision. The discovery of the Higgs Boson in 2012 was of the first category, a direct discovery at high energies.

Flavour factories work differently. They operate at much lower energies (about 1000 times lower than the Large Hadron collider), but are collecting huge amounts of data to precisely test the standard model to find hints for unknown physics effects. One of the current flavour physics experiments is Belle II in Japan. There physicists try to find hints explaining the asymmetry between matter and anti-matter seen at the big bang, and are searching for dark matter candidates, as well as other indications of deviations from the standard model. By precisely measuring the standard model processes it is possible check for particles 10,000 times heavier than the energies used in Belle II, and 10 times heavier of what the LHC can achieve in direct searches.

This talk focuses on the challenges that modern high energy physics experiments, as well as other experiments are facing, and how to tackle them, as well as the public relevance of the research fields.