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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"It's just a prank, bro": inside YouTube’s most twisted genre

Despite endless headlines and media scrutiny, catchphrases such as "it was a social experiment" and "block the haters" have allowed YouTube's dangerous pranking culture to continue unregulated. 

A year and five months after the worst prank video ever was uploaded to the internet, its crown has been usurped. In November 2015, YouTuber Sam Pepper made headlines after he filmed a video entitled “KILLING BEST FRIEND PRANK”. In the video, Pepper kidnaps a man before forcing him to watch his friend be “murdered” by a masked figure. Rocking on the chair he has been tied to, the victim sobs and shouts: “We’re just kids”.

Last week, an actual child – aged nine – was victim to a similarly distressing “prank”. Michael and Heather Martin, of the YouTube channel DaddyOFive, poured disappearing ink on to their son Cody’s carpet before – in Heather’s words – “flipping out” on the child.

“What the fuck did you do,” yells Heather to summon Cody to his room. “I swear to God I didn’t do that,” screams and cries Cody as his parents verbally berate him. His face goes red; he falls to his knees.

You won’t find either of these videos on either of their creators’ channels today. After considerable backlash, Pepper deleted his video and DaddyOFive have now made all of their videos (bar one) private. The Martins have faced international scrutiny after being called out by prominent YouTuber Philip DeFranco, who collated a video of clips in which Cody is “pranked” by his family. In one, Cody appears to be pushed face-first into a bookcase by his father. In another, a visibly distressed Cody sobs while his father says: “It’s just a prank bro.”

These five words have been used to justify some of the most heinous pranks in YouTube history. Sam Pepper famously called a video in which he pinched the bottoms of unsuspecting women, a “social experiment”. Usually, though, creators’ excuses follow a pattern. “It was just a prank,” they say. Then, if the heat doesn't subside: “Actually, it was fake.”

Three months after his “KILLING BEST FRIEND” prank, Pepper claimed the video – and all of his other prank videos – were staged. In a video entitled “Family Destroyed Over False Aquisations [sic]” the Martins have now also claimed that their videos are scripted. “We act them out,” says Michael. It seems many on the internet remain sceptical. The Child Protection Services website for Maryland – where the Martins live – has crashed after Redditors encouraged one another to report the family. If the Martins’ videos are indeed staged, Cody is one of the shining child actors of our time.

Though the Martins might yet face severe consequences for their pranks, it wouldn’t be surprising if they didn’t.  The “Just a prank”/“No it’s fake” cycle means that despite multiple headline-grabbing backlashes, YouTube pranking culture continues to thrive. Boyfriends pretend to throw their girlfriend’s cats out windows; fathers pretend to mothers that their sons have died. YouTubers deliberately step on strangers' feet in order to provoke fights. Sometimes, yes, pranksters are arrested for faking robberies, but in the meantime their subscribers continue to grow in their millions.

At present, there is no regulatory body that examines YouTube. Pranksters who break the law are arrested, but children whose daily lives are filmed for the site are not protected by the same regulations that safeguard child actors from being overworked or exploited. Though the communications authority Ofcom has guidelines about wind-up calls and consent, it does not regulate YouTube. The BBC were famously fined £150,000 by the body after Russell Brand and Jonathon Ross prank called Andrew Sachs, yet internet pranks remain out of its jurisdiction.

Though YouTube removes videos that breach its “Community Guidelines”, it seems illogical that we trust the service to police itself. Since the invention of the radio, we have assumed that independent bodies are needed to scrutinise the media – so why you should the largest video-sharing platform on the planet be exempt? No one is truly looking out for either the pranking victims or the children of YouTube. God forbid, like Cody, if you are both.

It is also arguable that YouTube pranks need more regulation than those broadcast on TV. Britain’s favourite pranking shows revolve around humiliating comedians themselves – Trigger Happy TV, Balls of Steel, Jackass – or are very soft (think a man pretending to be both a mime and a policeman) in nature. When someone is outright humiliated on TV, it’s because they are seen to be “fair game”, such as in Comedy Central’s Fameless Prankers, where people desperate to be famous are forced into increasingly humiliating situations. On YouTube, there are no consent forms or waivers to ensure filming remains ethical, and YouTube pranksters often target more vulnerable people.

“There’s an element of power here with the parents and it seems this is very top-down,” says Jonathan Wynn, a sociology professor at the University of Massachusetts who has written on pranks in the past. Wynn explains that traditionally pranks mock status and hierarchy, such as when court jesters taunted kings. When pranks come from the top down, Wynn says they allow a group to bond emotionally – arguably something the Martins are attempting as a family. Nonetheless, Wynn notes this would work better if the children also pranked their parents equally. “In this case the status differential is quite high, when you have children and parents.”

Traditionally, the mainstream media has had little room for this type of content. In 2012, two radio DJs attempted to prank the Duchess of Cambridge Kate Middleton by calling the hospital she was staying at, but instead tricked two nurses. When one of these nurses, Jacintha Saldanha, died by suicide days later, the episode seemed the ultimate illustration of the recklessness of pranks that “punch down”.

Conversely, status differentials are a large part of YouTube prank culture. Rather than attacking people in power, YouTube pranks are often played by those in power (the YouTube famous) on those who have lower social status. Frequently, boyfriends prank girlfriends, for example, and since 2014, white pranksters have filmed “in the hood” pranks provoking young black men. In “The N Word Prank!!” famous internet prankster Roman Atwood goes around saying “What’s up my neighbour” to people of colour, knowing that it will be misheard as a racial slur. In the context of this pranking culture, a parent pranking a child to the point of tears seems almost inevitable.

Perhaps, then, it is easy to understand why Michael and Heather Martin “prank” their children – it is harder to understand why anyone is watching. The DaddyOFive channel has over 750,000 subscribers, with over 7,000 of these subscribing after Philip DeFranco’s video accused the family of “abusing” their children. In order to defend themselves, the Martins initially employed another YouTube rhetoric, on top of “just a prank bro”. In a since deleted video, they invited their fans to “block the haters”.

This phrase is ingrained in online culture, and has allowed internet celebrities to dismiss criticism for years. By painting anyone who is critical as “jealous” or a “hater”, YouTubers can ensure their fans ignore their words and therefore stay loyal. In a video response to Philip DeFranco, the Martins riffed off a popular meme and placed spoons over their eyes to symbolise this mentality, and now fans as young as 12 are copying this action to show their support. When I search the hashtag used by the family’s supporters to see if anyone might be willing to explain why they still love the channel, I am faced with the reality that most of DaddyOFive’s fans are children. Though YouTube’s minimum sign-up age is 13, there is nothing really stopping children from watching – and normalising – harmful content, particularly when it is disguised as a “prank”.

In this context, it doesn’t matter in the slightest whether a prank is faked. Sam Pepper might have asked his friend's permission before he fake-kidnapped him, and perhaps Michael Martin was only pretending when he pushed his son into a bookcase. Neither of these facts will prevent children – 19 percent of whom have a desire to be famous – from copying these actions in order to promote their own YouTube channels. Even if a YouTuber is punished for a dangerous pranking video, there are thousands of other pranksters ready and willing to take their place. 

It remains to be seen whether the Martins will continue with their YouTube channel. At the end of their now infamous invisible ink prank, Michael asks Cody to “do the outro” – the concluding section of a YouTube video. Wiping his nose and still red in the face, Cody rattles off his script at alarming speed.“Thank you guys for watching this video if you like this video and want to see more videos like this one leave a comment down the section below and don’t forget to follow us on Twitter, Instagram, Facebook, Snapchat… and don’t forget to… Like and Subscribe.” 

Since the backlash, Michael has added a new line into the “About” section of the DaddyOFive YouTube channel. After reiterating that the videos are fake, he writes: “no child was harmed in the making of our videos”. 

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

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