Investigators of the ATLAS and CMS experiments of the Large Hadron Collider observe, for the first time, the process of decomposition of the Higgs.
Despite the discovery of the Higgs Boson six years ago, no one had yet managed to observe its mysterious decomposition process. According to the Standard Model, the great Theory that groups all the known particles and forces of Nature, the Higgs should be decomposed, in 60% of the occasions, in quarks “background”, one of the “flavors” or more massive types of quarks, the tiny particles that constitute protons and neutrons within the atomic nucleus.And now, using a large number of data from the Large Hadron Collider (LHC), the researchers of the ATLAS and CMS experiments have finally managed to “hunt” the elusive boson just at the moment, as predicted by the The theory was decomposed into two particles: a bottom quark and its antimatter equivalent, an anti-fund quark. The results of the research have just been published in two articles that can be consulted here and here.Since the discovery of the Higgs in 2012, physicists had tried futilely to observe this process, both to confirm the predictions of the Standard Model and to underscore its gaps and the need to look for a new Physics capable of explaining what the Standard Model can not. The problem is that the process of decomposing the Higgs is extraordinarily difficult to “catch” while it happens. The boson, in effect, is produced by a collision between two protons. If during the collision two gluons (the particles that hold together protons and neutrons together) merge and produce two “up” quarks, said quarks can recombine into a Higgs Boson. The whole process takes place in an incredibly short time: before decomposing, the Higgs exists only during the seventy-second part of a second.
There are several possible ways in which these particles can decompose and be observed with relative ease. But with the background quarks the thing becomes more complicated, since in each proton-proton collision there is a real rain of secondary particles, including the bottom quarks, which in turn quickly decompose into other particles. Given that the existence of the Higgs is so brief, until now it had been impossible to determine if the detected background quark were effectively the result of a decomposing Higgs boson or other background processes caused by the proton collision.
To clarify things, the ATLAS and CMS detectors combined their data and analyzed it to try to find the background quarks between the particle rain produced by the collision. The second step was to trace those background quarks to a Higgs boson and verify that, indeed, they were the product of their decomposition. According to Chris Palmer, a physicist at Princeton University who worked on the CMS data analysis, “Finding a single event that resembles the background quarks caused by a Higgs boson is not enough, we needed to analyze hundreds of thousands of events before of being able to shed light on this process, which happens in the middle of a mountain of background events of similar appearance “. Finally, the researchers managed to find what they were looking for and could announce that they had witnessed, for the first time, the decomposition of a Higgs Boson. The results open the doors to a much more detailed study of the Higgs and the way it interacts with other matter, including particles that have not yet been discovered (such as those of dark matter), which would be equivalent to entering for the first time Once in the field of a new Physics able to explain what today does not have, yet, explanation.
The next step in the investigation will be to refine the measurements to study the Higgs decomposition at a much higher resolution.
CMS Collaboration, 2018. Observation of Higgs boson decay to bottom quarks. arxiv.org. Available at: arxiv.org/abs/1808.08242
ATLAS Collaboration, 2018. Observation of H → bb¯ decays and VH production with the ATLAS detector. arxiv.org. Available at: https://arxiv.org/abs/1808.08238