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.

ILONA WELLMANN/MILLENNIUM IMAGES, UK
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How the internet has democratised pornography

With people now free to circumvent the big studios, different bodies, tastes and even pubic hair styles are being represented online.

Our opinions and tastes are influenced by the media we consume: that much is obvious. But although it’s easy to have that conversation if the medium we are discussing is “safe for work”, pornography carries so much stigma that we only engage with it on simple terms. Porn is either “good” or “bad”: a magical tool for ­empowerment or a destructive influence on society. Many “pro-porn” campaigners shy away from nuanced critique, fearing it could lead to censorship. “Anti-porn” campaigners, convinced that porn is harmful by definition, need look no further than the mainstream tube sites – essentially, aggregators of clips from elsewhere – to gather examples that will back them up.

When we talk about the influence of porn, the emphasis is usually on a particular type of video – hardcore sex scenes featuring mostly slim, pubic-hairless women and faceless men: porn made for men about women. This kind of porn is credited with everything from the pornification of pop music to changing what we actually do in bed. Last year the UK government released a policy note that suggested porn was responsible for a rise in the number of young people trying anal sex. Although the original researcher, Cicely Marston, pointed out that there was no clear link between the two, the note prompted a broad debate about the impact of porn. But in doing so, we have already lost – by accepting a definition of “porn” shaped less by our desires than by the dominant players in the industry.

On the day you read this, one single site, PornHub, will get somewhere between four and five million visits from within the UK. Millions more will visit YouPorn, Tube8, Redtube or similar sites. It’s clear that they’re influential. Perhaps less clear is that they are not unbiased aggregators: they don’t just reflect our tastes, they shape what we think and how we live. We can see this even in simple editorial decisions such as categorisation: PornHub offers 14 categories by default, including anal, threesome and milf (“mum I’d like to f***”), and then “For Women” as a separate category. So standard is it for mainstream sites to assume their audience is straight and male that “point of view” porn has become synonymous with “top-down view of a man getting a blow job”. Tropes that have entered everyday life – such as shaved pubic hair – abound here.

Alongside categories and tags, tube sites also decide what you see at the top of their results and on the home page. Hence the videos you see at the top tend towards escalation to get clicks: biggest gang bang ever. Dirtiest slut. Horniest milf. To find porn that doesn’t fit this mould you must go out of your way to search for it. Few people do, of course, so the clickbait gets promoted more frequently, and this in turn shapes what we click on next time. Is it any wonder we’ve ended up with such a narrow definition of porn? In reality, the front page of PornHub reflects our desires about as accurately as the Daily Mail “sidebar of shame” reflects Kim Kardashian.

Perhaps what we need is more competition? All the sites I have mentioned are owned by the same company – MindGeek. Besides porn tube sites, MindGeek has a stake in other adult websites and production companies: Brazzers, Digital Playground, Twistys, PornMD and many more. Even tube sites not owned by MindGeek, such as Xhamster, usually follow the same model: lots of free content, plus algorithms that chase page views aggressively, so tending towards hardcore clickbait.

Because porn is increasingly defined by these sites, steps taken to tackle its spread often end up doing the opposite of what was intended. For instance, the British government’s Digital Economy Bill aims to reduce the influence of porn on young people by forcing porn sites to age-verify users, but will in fact hand more power to large companies. The big players have the resources to implement age verification easily, and even to use legislation as a way to expand further into the market. MindGeek is already developing age-verification software that can be licensed to other websites; so it’s likely that, when the bill’s rules come in, small porn producers will either go out of business or be compelled to license software from the big players.

There are glimmers of hope for the ethical porn consumer. Tube sites may dominate search results, but the internet has also helped revolutionise porn production. Aspiring producers and performers no longer need a contract with a studio – all that’s required is a camera and a platform to distribute their work. That platform might be their own website, a dedicated cam site, or even something as simple as Snapchat.

This democratisation of porn has had positive effects. There’s more diversity of body shape, sexual taste and even pubic hair style on a cam site than on the home page of PornHub. Pleasure takes a more central role, too: one of the most popular “games” on the webcam site Chaturbate is for performers to hook up sex toys to the website, with users paying to try to give them an orgasm. Crucially, without a studio, performers can set their own boundaries.

Kelly Pierce, a performer who now works mostly on cam, told me that one of the main benefits of working independently is a sense of security. “As long as you put time in you know you are going to make money doing it,” she said. “You don’t spend your time searching for shoots, but actually working towards monetary gain.” She also has more freedom in her work: “You have nobody to answer to but yourself, and obviously your fans. Sometimes politics comes into play when you work for others than yourself.”

Cam sites are also big business, and the next logical step in the trickle-down of power is for performers to have their own distribution platforms. Unfortunately, no matter how well-meaning your indie porn project, the “Adult” label makes it most likely you’ll fail. Mainstream payment providers won’t work with adult businesses, and specialist providers take a huge cut of revenue. Major ad networks avoid porn, so the only advertising option is to sign up to an “adult” network, which is probably owned by a large porn company and will fill your site with bouncing-boob gifs and hot milfs “in your area”: exactly the kind of thing you’re trying to fight against. Those who are trying to take on the might of Big Porn need not just to change what we watch, but challenge what we think porn is, too.

The internet has given the porn industry a huge boost – cheaper production and distribution, the potential for more variety, and an influence that it would be ridiculous to ignore. But in our failure properly to analyse the industry, we are accepting a definition of porn that has been handed to us by the dominant players in the market.

Girl on the Net writes one of the UK’s most popular sex blogs: girlonthenet.com

This article first appeared in the 16 February 2017 issue of the New Statesman, The New Times