Supersymmetry Dealt Another Blow By LHC

Large Hadron Collider. Maximilien Brice; Claudia Marcelloni. CERN

The “supersymmetry” theory has just been dealt another blow by the Large Hadron Collider (LHC). New data from ultra-high-speed proton collisions has provided fresh evidence of subatomic activity and this new insight is consistent with the mainstream Standard Model of particle physics.

To understand the significance of these results, it’s important to go back to the basics. The Standard Model describes the fundamental particles that make up the universe and how they interact. It’s currently one of the best descriptions of the subatomic world, according to CERN, but there are some glaring gaps in information. It can’t describe gravity, can’t explain why there is dark matter, and can't predict the mass of the Higgs Boson.  

There are extensions to the Standard Model and researchers are looking for discrepancies within it that could be indications of new physics. This is where supersymmetry theory comes in.

“Supersymmetry predicts that every particle in the Standard Model has a so-called partner, also known as superpartners particles, which could solve a number of problems. For example, the superpartners could be candidates for dark matter,” William Sutcliffe, a Ph.D. student at Imperial College London’s High Energy Physics Group, tells IFLScience.

Sutcliffe was among a large international team of scientists who looked into the behavior of quarks, which are subatomic particles that make up protons and neutrons. There are six different types, or flavors, of quarks: up/down, charm/strange, and top/bottom. Researchers specifically looked at the bottom quark, also known as the 'beauty quark,' which is heavier and able to shift shape. The bottom quark usually transitions to a charm quark, but in rarer occasions it can transform into up quarks.

“We studied the transition of a bottom quark to an up quark and previously in this transition there have been some discrepancies that pointed towards right handed coupling. This could be an extension of the Standard Model,” Sutcliffe explains. “Supersymmetry theory is one way you could have a right handed coupling.”

In the findings, published in the journal Nature Physics, the measurements didn’t show any right-handed coupling. In the end, researchers obtained a result that was consistent with the Standard Model: bottom quarks seemingly only decay into up quarks if they have a left-handed spin, ABC reports. This is a blow to supersymmetry, but that hasn’t ruled out the theory. And just the fact that researchers were able to do this measurement, which was previously thought to be too challenging, is impressive.

“It’s quite a big deal that we were able to measure this transition of bottom quark to up quark. It’s like searching for a needle in a haystack,” Sutcliffe says.

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