The Large Hadron Collider, on the Franco-Swiss border near Geneva. Photo: Getty Images
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The Large Hadron Collider has made another exciting quantum discovery

Scientists working on one of the four experiments at the LHC have gathered enough evidence to confirm the existence of a four-quark particle.

Since the spectacular discovery of the Higgs boson in 2012, physicists at the Large Hadron Collider (LHC), the gigantic particle accelerator outside Geneva, have suffered a bit of a drought when it comes to finding new particles. In a welcome relief, the LHCb collaboration, who run one of four large experiments at the LHC, have announced one of the most genuinely exciting observations to come out of the 27km super-collider so far – an exotic particle that cannot be explained by current theories.

In the early 1930s physicists had a clean picture of the subatomic particles that make up our world. Every known atom has a tiny nucleus at its heart surrounded by a cloud of electrons, and each nucleus was made out of varying numbers of protons and neutrons. However, as the decades wore on a number of new, and somewhat unwelcome, particles were discovered, at first in detectors studying particles from outer space and later in particle-collider experiments.

By the 1950s, dozens of apparently elementary particles had been discovered, causing frustration among physicists who often brandish an inability to memorise a list of facts as a badge of honour. The famous physicist Enrico Fermi perhaps best expressed the mood of his colleagues in an infamous remark:

Young man, if I could remember the names of these particles, I would have been a botanist.”

Help came in the 1950s when physicists came up with a new model that explained most of these particles as being made up of a small number of truly elementary particles. Borrowing a line from James Joyce’s Finnegans Wake (a book that is even harder to understand than quantum field theory), Murray Gell-Mann dubbed these new particles “quarks”.

By the late 1960s the existence of quarks had been verified experimentally. We now know that there are six in total – the up, down, strange, charm, bottom and top quarks, along with six antiquarks (their anti-matter copies).

The quark model neatly explained all these peculiar particles. Protons, neutrons and many others besides are made of three quarks, belonging to a family known as baryons. Alternatively, a quark and an antiquark can pair up to form a meson.

Since then the quark model has been extremely successful, and is now a cornerstone of our understanding of particle physics. It was only at the turn of the millennium that some strange results started to suggest that the model might be incomplete. Until 2003 quarks had only been seen in twos or threes, but then a number of particles that looked like combinations of four quarks started to reveal themselves.

In 2008 the Belle Collaboration in Japan reported the observation of a new exotic particle – the unfortunately drably named Z(4430) (where for its negative charge). This has a mass that places it in a dense forest of charmonium states – particles that are made up of a charm quark and a charm antiquark. Crucially though, the Z is electrically charged whereas all charmonium states must be neutral, clearly marking it out as something unusual.

After a careful analysis of data from 25,000 decays of mesons resulting from more than 180 trillion collisions at the LHC in 2011 and 2012, the new announcement confirms the existence of Z(4430) with extremely high confidence. The particle was observed with an overwhelming significance of 13.9 sigma, well above the usual 5 sigma threshold required to declare a discovery. LHCb also went further than Belle by measuring the spin and parity of Z(4430), two quantum-mechanical properties that give a firm handle on the internal makeup of the particle.

The observation by LHCb is important because few physicists will take a result seriously until it has been seen by two independent experiments. This is why hundreds of millions of Euros were spent building two large detectors at the LHC. The observation of the Higgs boson by two independent teams, ATLAS and CMS, was what really convinced the scientific community that the particle was real.

This result is the clearest evidence yet of the existence of a tetraquark – a four-quark state, with the LHCb analysis suggesting that Z(4430) is most likely to be made of a charm, anti-charm, down and anti-up quark. Theorists are now able to add a whole new type of particle to the quark model and begin the hard work of trying to understand exactly how these four quarks are bound together.

Meanwhile, physicists working at the LHC experiments will continue to explore unmapped regions of the subatomic world, with the hope of turning up more members of this exotic new family. Now that we know that at least one is out there, it is very unlikely that Z(4430) is alone.The Conversation

Harry Cliff is affiliated with the University of Cambridge, CERN, the LHCb experiment.

This article was originally published on The Conversation. Read the original article.

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Did your personality determine whether you voted for Brexit? Research suggests so

The Online Privacy Foundation found Leave voters were significantly more likely to be authoritarian and conscientious. 

"Before referendum day, I said the winners would be those who told the most convincing lies," Paul Flynn, a Labour MP, wrote in these pages. "Leave did." The idea that those who voted for Brexit were somehow manipulated is widely accepted by the Remain camp. The Leave campaign, so the argument goes, played on voters' fears and exploited their low numeracy. And new research from the Online Privacy Foundation suggests this argument may, in part at least, be right. 

Over the last 18 months the organisation have researched differences in personality traits, levels of authoritarianism, numeracy, thinking styles and cognitive biases between EU referendum voters. The organisation conducted a series of studies, capturing over 11,000 responses to self-report psychology questionnaires and controlled experiments, with the final results scheduled to be presented at the International Conference on Political Psychology in Copenhagen in October 2017.

The researchers questioned voters using the "Five Factor Model" which consists of five broad personality traits - Openness, Conscientiousness, Extraversion, Agreeableness and Neuroticism. They also considered the disposition of authoritarianism (it is not considered a personality trait). Authoritarians have a more black and white view of the world around them, are more concerned with the upkeep of established societal traditions and have a tendency to be less accepting of outsiders. 

So what did they uncover? Participants expressing an intent to vote to leave the EU reported significantly higher levels of authoritarianism and conscientiousness, and lower levels of openness and neuroticism than voters expressing an intent to vote to remain. (Conscientiousness is associated with dependability, dutifulness, focus and adherence to societal norms in contrast to disorganisation, carelessness and impulsivity.)

Immigration in particular seems to have affected voting. While authoritarians were much more likely to vote Leave to begin with, those who were less authoritarian became increasingly likely to vote Leave if they expressed high levels of concern over immigration. These findings chime with research by the Professors Marc Hetherington and Elizabeth Suhay, which found that Americans became susceptible to "authoritarian thinking" when they perceived a grave threat to their safety. 

Then there's what you might call the £350m question - did Leave voters know what they were voting for? When the Online Privacy Foundation researchers compared Leave voters with Remain voters, they displayed significantly lower levels of numeracy, reasoning and appeared more impulsive. In all three areas, older voters performed significantly worse than young voters intending to vote the same way.

Even when voters were able to interpret statistics, their ability to do so could be overcome by partisanship. In one striking study, when voters were asked to interpret statistics about whether a skin cream increases or decreases a rash, they were able to interpret them correctly roughly 57 per cent of the time. But when voters were asked to interpret the same set of statistics, but told they were about whether immigration increases or decreases crime, something disturbing happened. 

If the statistics didn't support a voter's view, their ability to correctly interpret the numbers dropped, in some cases, by almost a half. 

Before Remoaners start to crow, this study is not an affirmation that "I'm smart, you're dumb". Further research could be done, for example, on the role of age and education (young graduates were far more likely to vote Remain). But in the meantime, there is a question that needs to be answered - are political campaigners deliberately exploiting these personality traits? 

Chris Sumner, from the Online Privacy Foundation, warns that in the era of Big Data, clues about our personalities are collected online: "In the era of Big Data, these clues are aggregated, transformed and sold by a burgeoning industry."

Indeed, Cambridge Analytica, a data company associated with the political right in the UK and US, states on its website that it can "more effectively engage and persuade voters using specially tailored language and visual ad combinations crafted with insights gleaned from behavioral understandings of your electorate". It will do so through a "blend of big data analytics and behavioural psychology". 

"Given the differences observed between Leave and Remain voters, and irrespective of which campaign, it is reasonable to hypothesize that industrial-scale psychographic profiling would have been a highly effective strategy," Sumner says. By identifying voters with different personalities and attitudes, such campaigns could target "the most persuadable voters with messages most likely to influence their vote". Indeed, in research yet to be published, the Online Privacy Foundation targeted groups with differing attitudes to civil liberties based on psychographic indicators associated with authoritarianism. The findings, says Sumner, illustrate "the ease with which individuals' inherent differences could be exploited". 

Julia Rampen is the digital news editor of the New Statesman (previously editor of The Staggers, The New Statesman's online rolling politics blog). She has also been deputy editor at Mirror Money Online and has worked as a financial journalist for several trade magazines. 

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