A highlight of the traditional Nobel Laureate Meeting in Lindau, Germany, which ended on July 1st, was a distinguished panel on particle physics that tried to glimpse beyond the standard model.
The panel discussion at the 66th Nobel Laureate Meeting in Lindau was titled “Glimpses Beyond the Standard Model”. The moderator of the panel, the particle physicist Felicitas Pauss (ETH Zurich), recalled the same podium discussion back in 2012. At that time, the scientists gathered in Lindau were surprised by the news that the Higgs boson has been experimentally proved at CERN. The participants of this year’s Lindau meeting would have gladly taken note of such an extraordinary news. After all, there are rumours about a possible upcoming discovery of a new particle with a mass of about 750 giga-electron-volts (GeV) sine several months. However, it is currently still open whether or not the new data being collected at the Large Hadron Collider (LHC) at CERN will confirm such a discovery.
Silence of CERN physicists
The presence of Fabiola Gianotti, the CERN Director General, via video conference did not change anything. “This is the question everyone asks for at the moment”, said Gianotti, who was the spokesperson for the ATLAS experiment in 2012 and announced the Higgs discovery at that time. “Our experiments do not yet have any official results”. Carlo Rubbia, who was a leading scientist during the discovery of the W and Z bosons in 1983 and received the Nobel Prize a year later together with Simon van der Meer, tried to prod Fabiola Gianotti hoping she would maybe still reveal something on the secret: “Are physicists at CERN currently with a laughing or a crying face on the road”, he asked Gianotti via video. But CERN physicists eluded any response. They consoled the audience pointing to the upcoming ICHEP conference in early August. The Lindau meeting had to go on without a sensation from CERN this year.
Although experimental data to put the standard model of particle physics in questions are currently still lacking, there were enough interesting topics to discuss in Lindau. The Standard Model is not a complete theory, at least this much is clear since a long time, because it describes the physical world very accurately, but not entirely. An important theoretical approach, which goes beyond the current Standard Model, is super-symmetry. This approach is guided by the basic idea that there exists for every elementary particle a super-symmetric partner. David Gross, theoretical physicist and Nobel laureate of the year 2004, has high hopes that the LHC will deliver new hints for super-symmetry in the coming years, as he emphasized in Lindau: “Hopefully, otherwise I lose some bets.”
New, even bigger particle accelerators
One way to break the limits of the Standard Model in the field of high-energy physics is to make protons and other particles collide at even higher energies than 13 TeV now achieved at the LHC. “I'm a big fan of colliders”, said David Gross. In his dreams David Gross already sees particle accelerators operating at energies of 100 TeV. Such machines could be built “at CERN or anywhere else” to deepen our understanding of the elementary bricks of matter, he said.
In the same vein raised the American physicist Steven Chu, although he is not a particle physicist, but his main contribution is on influencing atoms with a laser (Nobel Prize in Physics 1997). Chu, who served as energy minister in the administration of President Obama from 2009 to 2013, said that questions about dark matter and dark energy are very clearly formulated nowadays. “Taking this into account it would by tragic if our society wouldn't afford providing the facilities needed to answer these questions.”
Fascination of neutrinos
But it is not only from large particle accelerators that physicists expect new experimental findings that go beyond the Standard Model. Another important source of new knowledge comes also from numerous experiments to detect and characterise elusive neutrinos as Takaaki Kajita stressed on the podium in Lindau. Kajita got the Nobel Prize last year together with the Canadian astro-physicist Arthur McDonald for the discovery of neutrino oscillation. This refers to the phenomenon by which neutrinos existing in three different types (electron neutrino, muon neutrino, tau neutrino) can turn into another during their journey through space.
Author: Benedikt Vogel