Performing precise calculations at the cutting edge of the high-luminosity LHC era

Although there are many unanswered questions about the Standard Model (SM) of particle physics, it is currently the best model that describes the world of particle physics. Experimental and theoretical physicists compete against each other in a healthy competition to scrutinize the SM and identify areas that require further explanation beyond the model’s well-known shortcomings, such as the neutrino mass.

Experiments conducted at the LHC and other facilities at CERN can detect certain signs that the data deviate slightly from theoretical predictions. It is important to continue to explore whether such potential deviations can reveal new physics or be explained by SM.

To distinguish signal from background in experiments, theoretical physicists must calculate all complex processes with great precision. This involves detailed investigations involving observable quantities such as the number of events and kinematic details of a particular process, which may reveal the footprint of as yet unknown phenomena.

Such calculations yield, for example, W boson mass measurement And that top quarksimilarly strong coupling constant.

Strong forces and their coupling are the least well-known of the SMs, but they govern nearly all processes at the LHC. Furthermore, precise calculations will help develop new techniques to describe scattering processes and explain how to simulate them efficiently.

These calculations were already difficult in the LEP era, but the LHC takes them to a new level, exploding computational complexity and requiring new ways to calculate scattering processes. Ta.

Various aspects of precision computation have become essential for data analysis in modern experiments. These calculations are needed for complex scattering amplitude calculations that describe the final state immediately after a collision, for example, the production of three she-particles after the collision of two protons. .

One notable example is the production of the Higgs boson, specifically associated with the two top quarks. With many possible generation mechanisms and end states, new physics can be introduced in different ways. Therefore, theoretical physicists must calculate each production mode with high precision.

Calculating scattering amplitude is only one part of a broader accuracy calculation. The other is the Monte Carlo event generator. These calculations aim to describe all stages of the scattering process, from the few particles produced in the collision to the hundreds of particles observed in the detector. At each stage, the underlying physics is interpreted probabilistically and simulated using Monte Carlo methods. Monte Carlo methods are essential for simulations that can be employed in experiments to robustly control systematic uncertainties in the analysis.

One important example is the fusion of vectors and bosons. In this fusion, the two quarks scatter and exchange weak bosons, producing the Higgs boson and other particles. Computing this process using a Monte Carlo generator is a very complex but important task. Because new physics may be hidden in the details of the final state.

“Decades ago, this was not possible. Today, our ability to describe data with up to 5% accuracy or better relies on the power of first-principles calculations and the complexity of the hadron collider environment. “I’m really looking forward to what the high-luminosity LHC and the future collider era will bring,” says theoretical physicist Pia Moni at CERN.