Imagine it’s your birthday, and instead of opening your gift, you decide to shake the box to guess what’s inside. This playful curiosity mirrors how scientists at the Large Hadron Collider (LHC) explore the universe’s deepest mysteries. They either look directly for new particles or use indirect methods to detect subtle hints of new physics.

At a recent conference in Boston, the CMS collaboration at CERN shared exciting results from their study of a rare particle decay. They focused on the B⁰ meson, a particle made of a bottom quark and a down quark. This particle can decay into a K*⁰ meson, which includes a strange quark and a down quark, and two muons, which are similar to electrons but heavier. This specific decay process is incredibly rare and is influenced by a transition known as a “penguin transition.” This makes it very sensitive to new, unknown particles.

To break it down, the B⁰ meson is a type of particle consisting of a bottom quark and a down quark. Quarks are fundamental building blocks of matter, and they come in different “flavors” like up, down, strange, and bottom. When a B⁰ meson decays, it transforms into other particles. In this case, it decays into a K*⁰ meson and two muons.

The K*⁰ meson is another type of particle, and it’s made of a strange quark and a down quark. This decay process is particularly interesting to physicists because it involves a “penguin transition,” a rare type of quantum process that can be influenced by new, undiscovered particles. If these new particles exist, they could affect how the B⁰ meson decays, potentially revealing hints of new physics beyond what we currently know.

To investigate this rare decay, the CMS team analyzed data collected between 2016 and 2018. They used several techniques to examine the decay process. One method involved measuring the rate at which the decay occurs. Another method was to compare two similar decays: one involving two muons and the other involving two electrons, to see if there’s a difference.

The team also looked at how the particles produced in the decay shared the energy and at what angles they moved away from each other. By examining these details, they calculated specific parameters and compared them with predictions from the Standard Model.

Most of their findings matched the predictions, but there were a couple of parameters that didn’t quite fit. These parameters, known as P5′ and P2, showed some tension with the expected results, especially for specific energies of the two muons. This discrepancy hints at the possibility of new physics, something beyond our current understanding.


One factor complicating the analysis is the presence of a charm quark in the penguin transition. The charm quark is another type of fundamental particle, and its involvement makes the Standard Model predictions less straightforward. This complexity creates a puzzle for physicists, as it is difficult to draw definitive conclusions from the data.

To solve this puzzle, scientists need more accurate predictions, more data, and improved techniques for analyzing these rare decays. Each piece of data brings them closer to potentially uncovering new aspects of the universe. While the recent findings are in line with previous results from other experiments, the level of precision has improved, bringing hope that future studies might finally reveal the secrets hidden in these rare decays.

The search for new physics is much like shaking the box of a gift; it’s about paying attention to the subtle clues that might tell us there’s something more than we currently understand. The work done by the CMS team is a step toward this goal, offering a glimpse of what might be out there, waiting to be discovered. As researchers continue to refine their methods and gather more data, the scientific community remains eager to see what new physics might be uncovered next.


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