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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Understanding anxiety – my inside view of a debilitating disorder and how to control it

Following a number of recent anxiety attacks, I set out to learn why this happens to me.

As I stepped out of the office one evening after a routine day at work, I found myself glued to the floor. Legs bolted, knees quivering, heart racing – I was cemented into the ground by something paralysing.

I had to work out what was happening, and fast. Was a looming deadline holding me back from leaving? Was an unread message on my phone stopping me in my tracks? Perhaps fatigue had set me on edge. Or that passerby with an unsettling stare caught me off-guard. Maybe it was something more surreal; maybe a sense of dread had taken over, as I started to perceive each onlooker as a potential source of fear. Whether it was all of those things or none of those things, I eventually realised that the sticky situation I had found myself in was the onset of an anxiety attack.

Anxiety is a disorder of varying forms. People may be affected by generalised anxiety disorder – characterised by excessive worrying (often without an identifiable trigger), a specific phobia or panic disorder, in which terror can overwhelm a person without warning. The sufferer experiences physical and mental symptoms of distress that include a feeling of restlessness, shortness of breath, and agitation, exacerbated by the uncontrollable spiralling of their thoughts, which can often be self-deprecating and debilitating.

I had been in this situation before. The rising tension makes for an overwhelming and often paranoid experience, but my awareness of the fact that I was indeed having an anxiety attack was enough to know that this feeling wouldn’t persist for an indefinite amount of time; it would eventually pass, as all anxiety attacks do.

After roughly half an hour of concentrated breathing, conscious changes in thought patterns and eventually moving to a quieter spot, I had managed to calm down.

Though I had managed my anxiety attacks before via similar means, I was curious to know – what exactly was happening during my attacks? What can specifically be done while they’re happening? And could the panic and jitters of anxiety ever be beneficial?

The biology of an anxiety attack

The biological basis of an anxiety attack is tied to the actions of the body’s autonomic nervous system – a division of our nervous system that, without conscious control, regulates our bodily organs and systems.

When stimulated, the autonomic nervous system kicks into gear, causing the release of adrenaline into the bloodstream. And that’s when things flare up.

Pulses of adrenaline are produced in response to a stimulus  one that causes the body to kick into a defensive fight-or-flight mode. With anxiety, these stressful stimuli include excessive thoughts, heightened worries, trauma triggers and objects posing as threats. Even subconscious phenomena have been proposed as provokers; it is known that sufferers may wake up from a night’s sleep in a bout of panic. The stimuli add to the existing level of distress, making a person’s breath shallower, often inducing profuse sweating, and initiating a dark foreboding, all in the space of a moment.

Combating anxiety

According to the NHS, there are a number of techniques that can be employed to manage the distressing symptoms of an attack. Staying in a fixed spot, deep breathing and actively issuing a challenge in your mind to the fears on which you may be fixating are crucial things to do in the immediate stages. I wasn’t sure whether in my latest case I had done this instinctively or out of habit from past struggles. Either way, the methods were relieving.

The end of an attack is reached through an eventual depletion of adrenaline, which tells the body that it no longer needs to be on high alert. It brings with it tiredness but a welcome passing of the crisis. However, without a longer-term, pragmatic approach to tackling the disorder, it’s almost certain that an individual will face another intense period of anxiousness. So how should anxiety sufferers manage the issue over a longer period of time?

This is where therapy can be an extremely useful form of intervention. Cognitive behavioural therapy (CBT) is the most common form of therapy for the disorder, with research demonstrating its effectiveness in treating the closely related disorders under the umbrella of anxiety. CBT focuses on a reconfiguring of thought patterns, shifting perceptions and a redefining of negative sources of fear.

Recently, I spoke to David Potts, a CBT therapist, to discuss how therapy can be of benefit. He said: “In therapy we'd work on specifics. It would involve telling yourself what the triggers are. Often people have very negative views about what's happening to them [during an attack]; they'll think I'm having a heart attack or I'm going to die and those kinds of thoughts form a vicious cycle and the panic gets worse.”

According to Potts, being attuned to the occurrence of an anxiety attack is essential in taking active steps to overcome it. It can facilitate the process of calming down, allowing the person in the midst of an attack to separate the thoughts in their mind from the reality of a particular situation.

Therapy can also offer an individualised approach to understanding a person’s anxiety. Potts told me: “Often, from a therapy perspective, we are considering what’s happening to them [the patient] in their lives that lead them to be more anxious than other people. It could include things they’ve experienced in childhood, it could be ways that families are, or it could involve ways that they’ve learnt to manage different emotions.”

Beyond therapy, medication is available to aid anxiety. Appropriate to a disorder that can affect people in various ways, there are different types of medication. Selective serotonin reuptake inhibitors (SSRIs) are the most common form of medication. SSRIs are antidepressants that seek to increase levels of serotonin in our brains – a neurotransmitter thought to be central to the maintenance of mood. Other drugs available (in case of side effects from SSRIs) include serotonin and noradrenaline reuptake inhibitors (SNRIs), pregabalin and benzodiazepines. Though alleviating, medication is something that should supplement forms of therapy, as the pills themselves won’t solve the social triggers and problems that cause anxiety.

As people have increasingly moved towards holistic lifestyles, emphasis on exercise and dietary intake has been elevated. Eating healthier has been linked to reduced symptoms of anxiety, while exercise has been proven to reduce levels of stress in the long run. Reduced stress equates to a reduced risk of an anxiety attack.

Changes to the brain from exercise have been documented too. Researchers at Princeton University found that physical exercise generates excitable new brain cells in the hippocampus – an area of the brain involved in emotional responses. Though the excitability of the neurons would generally be unfavourable (priming the brain for anxiety), researchers found that the impact of exercise was one which had a calming effect, as the exercise was able to switch off the newly-generated, excitable neurons at times when they weren’t required.

When just a ten-minute walk has been shown to offer benefit, there seems to be very little to oppose the implementation of exercise as a form of therapy for anxiety.

Living with anxiety

Perhaps surprisingly, anxiety can be harnessed as a tool of empowerment for some. When it occurs at a smaller scale, it can serve as an informative warning against stressors, and help an individual focus and pinpoint their attention.

As a sufferer, acknowledgement of anxiety seems to be the key to unlocking the resources that can dull its impact. With carefully paid attention, responsibility and mindfulness, the waves of anxiety threatening to drench you can be reduced to smaller, more manageable ebbs and flows.