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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Forget “digital detoxes”. Spring clean your online life instead

Step one: remove the app on your phone which takes up the most time. 

In 2006, news broke that broke me. The British Heart Foundation unveiled a poster of a blonde girl guzzling a gallon of cooking oil. “What goes into crisps goes into you,” it read, as the charity declared that eating one packet of crisps a day equated to drinking five litres of oil a year.

I gave up crisps that Lent (an admirable act that was somewhat mitigated by devouring a six-pack of McCoy’s on Easter Sunday). Still, despite my continuing pack-a-day habit, the BHF’s statistic has never left me: 365 packets of salt and vinegar crisps are equal to five bottles of Filippo Berio. But other bad habits are harder to comprehend. Last week, I “liked” 36 things on Facebook, wrote ten tweets, and posted five Instagram pictures (two of which were selfies). What effect, if any, has this had on my mental and physical health? How much metaphorical cooking oil am I pouring into my body?

“You really don’t need to worry about the volume of your own social media interactions, based on the average digital user,” the founder of the digital detox specialists Time To Log Off, Tanya Goodin, told me. Goodin says that we “tap, click and swipe” our devices over 2,617 times a day and that the average person will post 25,000 selfies in their life.

Though these statistics seem shocking, what do they mean? What does swiping thousands of times a day do to our minds – or, for that matter, our thumbs? The experts are divided. In 2015, national newspapers spread stories suggesting that using an iPad would damage a toddler’s brain but the research didn’t mention the term “brain damage” once. In fact, as the Guardian pointed out in its debunking, studies produce mixed results: some say iPads help improve child literacy, others say they are distracting.

The studies about adults’ screentime are similarly hard to decipher. Heavy Facebook usage has been linked to depression but there isn’t any apparent cause and effect. Do depressed people use Facebook more, or does Facebook make us depressed? “Internet addiction disorder” (IAD) was a term originally coined as a hoax, but many now see it as a real and treatable problem. Yet it does not feature in the Diagnostic and Statistical Manual of Mental Disorders, and experts still struggle to set diagnostic criteria for it. How much internet is too much?

These academic ambiguities haven’t stopped the idea of the “digital detox” taking off. Detoxers refrain from using any electronics for a period of time in the hope that this will improve their mental health and real-world relationships. At the time of writing, if you search for “digital detox” on Instagram, you’ll find 25,945 people talking about their personal attempts. There are pictures of bike rides, sunsets and children playing, each posted – apparently without irony – to extol the virtues of getting off social media and turning off your phone.

Digital detoxing is also big business. Goodin runs workshops, retreats and camps where no electronics are allowed and the daily schedule consists of yoga, walking, swimming and drinking smoothies. The next one, in Italy, costs from £870 per head for a week. A multitude of such camps exist, as well as books, websites and guides on how to detox by yourself. To connect, man, you have to disconnect, you know?

All of this has made me a digital detoxing cynic. I don’t believe I need to switch off my phone to “live” better, because I believe my phone itself contains life. On Reddit, I can speak to strangers living hundreds of thousands of miles away about their lives. On Twitter, I can keep up to date – in real time – with news and events. If I want to learn yoga or make a smoothie, where will I go to find my local gym or the correct strawberry-to-spinach ratio? Technology can even inspire us to “get out more”. Last summer, the gaming app Pokémon Go spurred people to walk 2,000 more steps a day, and I’m willing to bet that brunch sales figures have skyrocketed since the invention of Instagram.

Digital detoxing relies on the vague idea that tech is somehow toxic. Even without scientific studies to back this up, most of us know from our own, anecdotal evidence how spending too much time on our phones can make us feel. We get down if our latest status doesn’t have enough likes, or our eyes hurt after the sixth “EXTREME PIMPLE POPPING” YouTube video in a row. So, at core, digital detoxing isn’t “wrong”: it is merely misguided. Instead of trying to cut out all technology for a week, we should be curbing our existing habits; rather than a digital detox, we should have a digital spring clean.

Delete – or hide – anyone on your Facebook friends list that you wouldn’t talk to in real life. Remove your work email from your phone (or ask your boss for a separate work phone if you absolutely need access). Delete the app that takes up most of your time – be it Facebook, Twitter or YouTube – so that you are forced to get to it manually, through your browser, and therefore become instantly more aware of how many times a day you open it up. Tanya Goodin also advises me to use my phone less at night. Essentially: go mild turkey. If this is too much and you believe you are addicted to your smartphone or laptop, then, of course, you should seek help (speak to your doctor or call the Samaritans on 116 123).

But most of us just need to get smarter about our internet use. Even if scientists proved that technology was damaging our brains, a week-long detox wouldn’t be the cure. Rather, we should focus on our bad personal habits and try to curb them. Do you get into too many arguments online? Do you ignore your partner because you’re staring at a screen? Do you post opinions you regret because you don’t think them through first? These behaviours are problematic – the internet itself isn’t. To control our lives, we shouldn’t switch off: we should get more switched on.

Amelia Tait is a technology and digital culture writer at the New Statesman.

This article first appeared in the 06 April 2017 issue of the New Statesman, Spring Double Issue

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