Interview, Conference Presentation
Harry Cliff: Particle Physics and the Large Hadron Collider | Lex Fridman Podcast #92
- The Large Hadron Collider (LHC) luminosity upgrade is anticipated to increase data collection rates by an order of magnitude in the near future, enabling sensitivity to new processes and potentially resolving beauty quark (b-quark) anomalies observed in recent data.
- If b-quark anomalies are confirmed as real signals of new quantum fields, the community plans to construct larger colliders, with the most optimistic timeline for data from proposed facilities like the Future Circular Collider (FCC) set for 2040 due to extensive R&D and political processes.
- The FCC project is estimated to cost approximately 30 billion euros with expenditures spanning from the present to 2070, initially featuring a 100-kilometer electron-positron collider to study the Higgs boson before transitioning to a long-term proton-proton phase for dark matter searches and early universe phase transitions.
- While some scientists predict a "decade more data" is needed to detect signals of new particles, others estimate the likelihood of the LHC directly discovering new particles in the near future is slim, though machine learning applied to trigger systems could significantly increase useful data recording.
- Supersymmetry, once the most popular solution to the Higgs fine-tuning problem, has yielded no evidence after a decade of data taking, prompting interest in alternative theories such as "partial compositeness" or the Higgs being composed of smaller entities.
- Probing the energies where unified quantum theories or string theory become testable is deemed extremely unlikely without unprecedented breakthroughs, as reaching the Planck scale would require an accelerator the size of the Milky Way.
- The Higgs field's precise value is expected to require fine-tuning to allow for a complex universe, with deviations potentially causing a massless universe or one dominated by black holes, while its non-zero value everywhere distinguishes it from shieldable fields like electromagnetism.
- The LHC, a 27-kilometer circumference machine buried 100 meters underground, fires protons at speeds near light to create disturbances in the Higgs field, though it was originally built to replace the Large Electron Positron Collider (LEP) which ceased operation in 1999.
- Machine learning techniques are being integrated to handle the LHC's trigger system, which must decide whether to record collisions among 40 million interactions per second from bunches containing 100 billion protons, as storing all raw data would exhaust global computing capacity.
- The matter-antimatter asymmetry observed in the universe, where the Big Bang should have resulted in equal parts annihilating into a photon-filled void, is being investigated through LHCb detector studies of beauty quark decays and potential exotic neutrino decays during the Higgs field's early universe phase transition.
- Historical context notes the prediction of W plus, W minus, Z, and Higgs bosons in the mid-1970s, with the former three discovered in 1983-84, while the LHC's 2008 launch followed a major technical setback involving a half-kilometer damage incident just days after initial switching on.
- The UK contributes between 100 and 200 million pounds annually to CERN, supporting an international collaboration that aims to explain why the universe is composed of matter despite theoretical expectations of equal matter and antimatter production.
- Theoretical expectations for new physics at the LHC included super partners at energies around the proton probe scale, a prediction that has not materialized, suggesting current energies may be insufficient to see rare processes without further data accumulation.
- Dark matter and dark energy constitute approximately 95% of the universe, and while accelerators offer a potential path to understanding them, there is no certainty regarding direct discovery, contrasting with the confirmed role of the Higgs field in providing mass to particles like electrons and quarks.