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

PROMOTED VIDEO
News
video
Life and Style
tech
Arts and Entertainment
Southern charm: Nicolas Cage and Tye Sheridan in ‘Joe’
filmReview: Actor delivers astonishing performance in low budget drama
Arts and Entertainment
While many films were released, few managed to match the success of James Bond blockbuster 'Skyfall'
film
Arts and Entertainment
Up my street: The residents of the elegant Moray Place in Edinburgh's Georgian New Town
tvBBC's The Secret History of Our Streets reveals a fascinating window into Britain's past
Extras
indybest
News
Albus Dumbledore, the headmaster of Hogwarts School of Witchcraft and Wizardry has been the teaching profession's favourite teacher
education
News
ebookA unique anthology of reporting and analysis of a crucial period of history
Sport
Luis Suarez looks towards the crowd during the 2-1 victory over England
sport
Life and Style
Cheesecake frozen yoghurt by Constance and Mathilde Lorenzi
food + drinkThink outside the cool box for this summer’s frozen treats
News
John Barrowman kisses his male “bride” at a mock Gretna Green during the Commonwealth Games opening ceremony
peopleBarrowman's opening ceremony message to Commonwealth countries where he would be sent to prison for being gay
Sport
Sir Bradley Wiggins removes his silver medal after the podium ceremony for the men’s 4,000m team pursuit in Glasgow yesterday
Commonwealth games Disappointment for Sir Bradley in team pursuit final as England are forced to settle for silver
Sport
Alistair Brownlee (right) celebrates with his gold medal after winning the men’s triathlon alongside brother Jonny (left), who got silver
England's Jodie Stimpson won the women’s triathlon in the morning
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
Latest stories from i100
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

SQL Report Analyst (SSRS, CA, SQL 2012)

£30000 - £38500 Per Annum + 25 days holiday, pension, subsidised restaurant: C...

Application Support Analyst (SQL, Incident Management, SLAs)

£34000 - £37000 Per Annum + excellent benefits: Clearwater People Solutions Lt...

Embedded Software / Firmware Engineer

£40000 - £45000 per annum + Pension, Holiday, Flexi-time: Progressive Recruitm...

Developer - WinForms, C#

£280 - £320 per day: Progressive Recruitment: C#, WinForms, Desktop Developmen...

Day In a Page

Backhanders, bribery and abuses of power have soared in China as economy surges

Bribery and abuses of power soar in China

The bribery is fuelled by the surge in China's economy but the rules of corruption are subtle and unspoken, finds Evan Osnos, as he learns the dark arts from a master
Commonwealth Games 2014: Highland terriers stole the show at the opening ceremony

Highland terriers steal the show at opening ceremony

Gillian Orr explores why a dog loved by film stars and presidents is finally having its day
German art world rocked as artists use renowned fat sculpture to distil schnapps

Brewing the fat from artwork angers widow of sculptor

Part of Joseph Beuys' 1982 sculpture 'Fettecke' used to distil schnapps
BBC's The Secret History of Our Streets reveals a fascinating window into Britain's past

BBC takes viewers back down memory lane

The Secret History of Our Streets, which returns with three films looking at Scottish streets, is the inverse of Benefits Street - delivering warmth instead of cynicism
Joe, film review: Nicolas Cage delivers an astonishing performance in low budget drama

Nicolas Cage shines in low-budget drama Joe

Cage plays an ex-con in David Gordon Green's independent drama, which has been adapted from a novel by Larry Brown
How to make your own gourmet ice lollies, granitas, slushy cocktails and frozen yoghurt

Make your own ice lollies and frozen yoghurt

Think outside the cool box for this summer's tempting frozen treats
Ford Fiesta is UK's most popular car of all-time, with sales topping 4.1 million since 1976

Fiesta is UK's most popular car of all-time

Sales have topped 4.1 million since 1976. To celebrate this milestone, four Independent writers recall their Fiestas with pride
10 best reed diffusers

Heaven scent: 10 best reed diffusers

Keep your rooms smelling summery and fresh with one of these subtle but distinctive home fragrances that’ll last you months
Commonwealth Games 2014: Female boxers set to compete for first time

Female boxers set to compete at Commonwealth Games for first time

There’s no favourites and with no headguards anything could happen
Five things we’ve learned so far about Manchester United under Louis van Gaal

Five things we’ve learned so far about United under Van Gaal

It’s impossible to avoid the impression that the Dutch manager is playing to the gallery a little
Screwing your way to the top? Good for Lana Del Rey for helping kill that myth

Screwing your way to the top?

Good for Lana Del Rey for helping kill that myth, says Grace Dent
Will the young Britons fighting in Syria be allowed to return home and resume their lives?

Will Britons fighting in Syria be able to resume their lives?

Tony Blair's Terrorism Act 2006 has made it an offence to take part in military action abroad with a "political, ideological, religious or racial motive"
Beyoncé poses as Rosie the Riveter, the wartime poster girl who became a feminist pin-up

Beyoncé poses as Rosie the Riveter

The wartime poster girl became the ultimate American symbol of female empowerment
The quest to find the perfect pair of earphones: Are custom, 3D printed earbuds the solution?

The quest to find the perfect pair of earphones

Earphones don't fit properly, offer mediocre audio quality and can even be painful. So the quest to design the perfect pair is music to Seth Stevenson's ears
US Army's shooting star: Lt-Col Steven Cole is the man Hollywood calls when it wants to borrow a tank or check a military uniform

Meet the US Army's shooting star

Lt-Col Steven Cole is the man Hollywood calls when it wants to borrow a tank or check a military uniform