Atomically challenged

It's big news for small matter. Electrons behaving flirtatiously in Germany may prompt scientists to re-write the laws of physics.

Crowds gather in the suburbs of northern Hamburg to watch one of the most famous German football teams, Hamburg SV. The ball moves back and forth and the crowd yells. Meanwhile, electrons whistle silently beneath their feet at close to the speed of light in experiments to observe the smallest structure of matter.

The electrons are created at the Deutsches Elektronen Synchrotron (Desy), Germany's national particle physics laboratory. Founded in 1959, today its principal machine is Hera (Hadron Elektron Ring Anlage) - a proton positron collider - and it is Europe's second international particle physics lab.

In recent weeks, the physicists who work on these experiments have become as excited as the football fans. They have uncovered data that could revolutionise their understanding of the laws that govern the universe.

Physicists understand the laws of physics in terms of the so-called Standard Model, which describes matter in terms of four fundamental forces (strong nuclear, weak nuclear, electromagnetic and gravity) acting on simple point- like particles known as quarks and leptons. This model, formulated in the 1970s, has withstood every subsequent challenge - although physicists know it is incomplete in many ways. It contains many arbitrary constants, and it does not incorporate the interaction of particles and the force of gravity.

The particles of matter in the universe, and their anti-particles, can be divided into quarks and leptons. The difference between them is their behaviour with respect to the most powerful of the four forces, the strong force, which binds the protons and neutrons inside the atomic nucleus, and confines the quarks themselves inside these protons and neutrons. While quarks are dominated by the strong force, leptons are totally immune to it. Their behaviour is controlled by the electromagnetic force, the most familiar everyday force which is responsible for operating electrical devices, and the weak force, responsible for the burning of stars and the decay of radioactive elements.

This very different behaviour of quarks and leptons is crucial to the world as we know it. For example, the electron is the lightest electrically charged lepton. Because they are unaffected by the strong nuclear force, electrons remain outside the atomic nucleus rather than being absorbed into it. Electrons are the active participants in all atomic behaviour. If they felt the nuclear force, the entire universe would be a soup of nuclear material.

In the 100 years since its discovery, the electron has seemed simple and well-behaved. It does not appear to have any size, it is completely stable, and it shows no interest in forming any more complicated or excited states with quarks or other leptons. But now, in the centenary of its discovery, the first evidence is accumulating that the electron may, after all, be involved in intimate relations with quarks.

This surprising suggestion comes from the two major experiments at Hera known as H1 and Zeus. These experiments involve large international collaborations of physicists and engineers. The main purpose is to fire electrons at protons at very high energies. By observing the energy and angle of the scattered electron, as well as the remnants left when the proton breaks up under the impact, the properties of the constituents - such as the quarks inside the proton - can be reconstructed. Hera can be thought of as the world's largest electron microscope, looking at the sub-nuclear rather than the molecular level of the best conventional electron microscopes.

A feature of both types of microscopes is that the higher the collision energy (that is, the more direct the clash) between electron and target, the smaller the detail which can be resolved. However, such energetic collisions are very infrequent. Far more commonly, an electron strikes a glancing blow off the quarks. But data from the rarest events at the very highest resolutions from Zeus and H1 indicate anomalies that have caused the excitement.

Until now, all data from the two experiments could be explained within the framework of the Standard Model. But on 19 February, both teams announced the first evidence that the electron is more likely to scatter from the quarks at high energies than predicted.

There are many possible explanations for this unexpected behaviour. The most likely is still that most ubiquitous of laws in experimental science, which can be formulated as "If Nature can fool you, she will".

Because the events in question are very rare, the two experiments each gathered only a handful. The statistics of small numbers means that the events observed might simply be a chance upward fluctuation which, as more events are gathered, will average out to return to the Standard Model prediction. But the larger the size of the excess observed, the smaller the chance that it can be a fluctuation.

It's like the National Lottery - there is a small chance that the number 15 will come up in two successive draws, and a smaller one of appearing in three successive draws, and so on. If 15 kept on coming up in draw after draw, a normal scientist would either formulate a new law of probability, or offer the more likely hypothesis that someone was introducing extra balls marked with a number 15. At Hera, the scientists are increasingly suspicious that something strange is going on, but can't yet point conclusively to the culprit.

The fact that both experiments see a similar effect makes a statistical fluke less likely, in which case a variety of explanations suggest themselves. The quantity of evidence is insufficient to favour a particular possibility; however, most involve new physics which would open up a new world of phenomena.

One interpretation is that a new type of particle, known as a "leptoquark", is being formed. Such particles would be a hybrid of a lepton - in this case an electron - with a quark. More electrons are scattering with quarks at high energies than predicted because at these very small distances, the electron and quark find they like to embrace each other and for a tiny instant form this new type of matter, the leptoquark, before falling apart again into leptons and quarks.

Conventional wisdom suggested that leptoquarks would not be the first new particle to be discovered. Therefore, if the new data stands the test of time, physics will need a major rethink: the effects would stretch back to our understanding of the Big Bang and the first fractions of a second of the life of the universe.

The writer is professor of experimental physics at the University of Bristol

For details on the Hera experiments, see http://www-h1.desy.de/h1/www/html/hiq2.html

News
The current recommendation from Britain's Chief Medical Officer, is that people refrain from drinking on at least two days a week
food + drinkTheory is that hangovers are caused by methanol poisoning
Life and Style
techConcept would see planes coated in layer of micro-sensors and able to sense wear and tear
News
Patrick Stewart in the classiest ice bucket to date
people
News
scienceExcitement from alien hunters at 'evidence' of extraterrestrial life
PROMOTED VIDEO
News
ebooksAn evocation of the conflict through the eyes of those who lived through it
Sport
David Moyes gets soaked
sport Moyes becomes latest manager to take part in the ALS challenge
Voices
A meteor streaks across the sky during the Perseid Meteor Shower at a wind farm near Bogdanci, south of Skopje, Macedonia, in the early hours of 13 August
voicesHagel and Dempsey were pure Hollywood. They only needed Tom Cruise, says Robert Fisk
Life and Style
Horst P Horst mid-fashion shoot in New York, 1949
fashionFar-reaching retrospective to celebrate Horst P Horst's six decades of creativity
News
Members and supporters of the lesbian, gay, bisexual, transgender (LGBT) community walk with a rainbow flag during a rally in July
i100
Life and Style
Black Ivory Coffee is made using beans plucked from elephants' waste after ingested by the animals
food + drinkFirm says it has created the "rarest" coffee in the world
Independent
Travel Shop
the manor
Up to 70% off luxury travel
on city breaks Find out more
santorini
Up to 70% off luxury travel
on chic beach resorts Find out more
sardina foodie
Up to 70% off luxury travel
on country retreats Find out more
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Software Developer (Java /C# Programmer)- London

£30000 - £45000 per annum: Harrington Starr: A global investment management fi...

Senior Network Engineer-(CCIE, CCNP, Cisco, London)

£65000 - £75000 per annum: Harrington Starr: Senior Network Engineer-(CCIE, CC...

Senior Network Analyst - (CCIE, Cisco, CISSP)

£70000 - £80000 per annum: Harrington Starr: Senior Network Analyst - (CCIE, C...

Senior Network Engineer-(Design, Implementation, CCIE)

£60000 - £80000 per annum: Harrington Starr: Senior Network Engineer-(Design, ...

Day In a Page

All this talk of an ‘apocalyptic’ threat is simply childish

Robert Fisk: All this talk of an ‘apocalyptic’ threat is simply childish

Chuck Hagel and Martin Dempsey were pure Hollywood. They only needed Tom Cruise
Mafia Dons: is the Camorra in control of the Granite City?

Mafia Dons: is the Camorra in control of the Granite City?

So claims an EU report which points to the Italian Mob’s alleged grip on everything from public works to property
Emmys look set to overhaul the Oscars as Hollywood’s prize draw

Emmys look set to overhaul the Oscars as Hollywood’s prize draw

Once the poor relation, the awards show now has the top stars and boasts the best drama
What happens to African migrants once they land in Italy during the summer?

What happens to migrants once they land in Italy?

Memphis Barker follows their trail through southern Europe
French connection: After 1,300 years, there’s a bridge to Mont Saint-Michel

French connection: After 1,300 years, there’s a bridge to Mont Saint-Michel

The ugly causeway is being dismantled, an elegant connection erected in its place. So everyone’s happy, right?
Frank Mugisha: Uganda's most outspoken gay rights activist on changing people's attitudes, coming out, and the threat of being attacked

Frank Mugisha: 'Coming out was a gradual process '

Uganda's most outspoken gay rights activist on changing people's attitudes, coming out, and the threat of being attacked
Radio 1 to hire 'YouTube-famous' vloggers to broadcast online

Radio 1’s new top ten

The ‘vloggers’ signed up to find twentysomething audience
David Abraham: Big ideas for the small screen

David Abraham: Big ideas for the small screen

A blistering attack on US influence on British television has lifted the savvy head of Channel 4 out of the shadows
Florence Knight's perfect picnic: Make the most of summer's last Bank Holiday weekend

Florence Knight's perfect picnic

Polpetto's head chef shares her favourite recipes from Iced Earl Grey tea to baked peaches, mascarpone & brown sugar meringues...
Horst P Horst: The fashion photography genius who inspired Madonna comes to the V&A

Horst P Horst comes to the V&A

The London's museum has delved into its archives to stage a far-reaching retrospective celebrating the photographer's six decades of creativity
Mark Hix recipes: Try our chef's summery soups for a real seasonal refresher

Mark Hix's summery soups

Soup isn’t just about comforting broths and steaming hot bowls...
Tim Sherwood column: 'It started as a three-horse race but turned into the Grand National'

Tim Sherwood column

I would have taken the Crystal Palace job if I’d been offered it soon after my interview... but the whole process dragged on so I had to pull out
Eden Hazard: Young, gifted... not yet perfect

Eden Hazard: Young, gifted... not yet perfect

Eden Hazard admits he is still below the level of Ronaldo and Messi but, after a breakthrough season, is ready to thrill Chelsea’s fans
Tim Howard: I’m an old dog. I don’t get too excited

Tim Howard: I’m an old dog. I don’t get too excited

The Everton and US goalkeeper was such a star at the World Cup that the President phoned to congratulate him... not that he knows what the fuss is all about
Match of the Day at 50: Show reminds us that even the most revered BBC institution may have a finite lifespan – thanks to the opposition

Tom Peck on Match of the Day at 50

The show reminds us that even the most revered BBC institution may have a finite lifespan – thanks to the opposition