CERN Update: LHC Experiment Finds 'Intriguing' Hints Of Physics Beyond Standard Model

Nothing excites particle physicists more than possible signs of “new physics.” Finding cracks in the Standard Model and heralding an era of “new physics” was one of the key goals outlined by researchers at the European Organization for Nuclear Research (CERN) when they restarted the Large Hadron Collider (LHC) in 2015.

Now, a team of researchers analyzing data collected by the LHCb experiment during the collider’s “Run 1” has revealed what might just be our first glimpse of physics beyond the Standard Model.

The scientists, who studied a particle called B meson (which is a class of hadrons containing a bottom quark), found an “intriguing” anomaly in the way it decays. Specifically, they found that instead of electrons and muons being produced with the same probability during the decay of B⁰ mesons — as the Standard Model predicts — decays involving muons occurred less often.

This observation goes against a crucial tenet of the Standard Model called lepton universality, which states that the difference in the mass of electrons and muons (both of which belong to a class of particles called leptons) notwithstanding, these particles should behave in the same way, and should have the same couplings to gauge bosons.

“While potentially exciting, the discrepancy with the Standard Model occurs at the level of 2.2 to 2.5 sigma, which is not yet sufficient to draw a firm conclusion. However, the result is intriguing because a recent measurement by LHCb involving a related decay exhibited similar behavior,” CERN said in a statement released Tuesday. “More data and more observations of similar decays are needed in order to clarify whether these hints are just a statistical fluctuation or the first signs for new particles that would extend and complete the Standard Model of particles physics.”

There are four fundamental forces in the universe — the strong force, the weak force, the electromagnetic force and the gravitational force. Of these, the first three result from the exchange of force-carrier particles, which belong to a broader group called bosons, and whose interactions — both among themselves and with matter particles such as quarks and leptons — are explained within a framework called the Standard Model.

In 2012, with the discovery of the Higgs boson, which is responsible for imparting mass to all other particles, scientists believed the last missing piece that completed the Standard Model had been found. However, even the completed version of this theory fails to incorporate gravity and explain the origin and preponderance of dark matter and dark energy in the universe.

So, in 2015, scientists restarted the LHC at an unprecedented energy of 6.5 teraelectronvolts per beam — compared to 4 TeV per beam in 2012 — with the aim of either breaking the Standard Model, or bolstering it further. They were also looking for the fabled “graviton” — a force-carrying particle for gravity — and evidence of supersymmetry — an extension of the Standard Model that predicts the existence of more massive “super partners” for every known particle.

So far, though, scientists have come away empty-handed — making this particular LHCb discrepancy all the more exciting.

“If this initial result becomes stronger with more data, it could mean that there are other, invisible particles involved in this process that see flavor,” Marie-Hélène Schune, a researcher on the LHCb experiment, told Symmetry magazine. “We’ll leave it up to the theorists’ imaginations to figure out what’s going on.”