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Posts Tagged ‘LHC

Higgsteria rising as trouble brews for standard model

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BaBar, still making trouble (Image: Peter Ginter/Getty Images)

by Lisa Grossman

Excitement about the Higgs boson is ramping up ahead of a hotly anticipated conference in Australia next month. But even if last year’s tentative signals of the particle are confirmed, a fresh analysis of data from a particle accelerator in California suggests that this may not complete the standard model of physics.

The Higgs boson is the missing piece of the standard model, our most successful description of how particles and forces interact. Last December, researchers at the Large Hadron Collider at CERN near Geneva, Switzerland, reported the most credible hints yet of the elusive particle.

Various bloggers claim these hints will grow less tentative once new data is revealed at the International Conference on High Energy Physics in Melbourne.

Theoretical physicist Peter Woit of Columbia University in New York wrote on his blog that the LHC’s two main experiments are seeing the same signal as in December – hinting at a Higgs with an energy of 125 gigaelectronvolts – but this time with greater statistical significance. Woit declined to name his sources but assured New Scientist they were “highly reliable”.

Too many taus

Still, for now, those rumours are just that. “It is still too premature to start going wild,” says Pauline Gagnon of CERN’s ATLAS experiment.

In the meantime, a new analysis from the BaBar experiment, which ran at the SLAC National Accelerator Lab in California until 2008, suggests the standard model is not what it seems.

According to the model, a particle called the B meson, studied by BaBar, decays to produce particles including a W boson, which then decays further into a tau particle and a tau neutrino. Now BaBar reports B mesons decaying into tau particles more often than the standard model predicts.

“It looks like the standard model has something in it that we don’t understand,” says BaBar spokesperson Michael Roney at the University of Victoria in British Columbia, Canada.

The BaBar team’s results are not statistically significant, yet, but they hope a Japanese experiment called Belle will confirm their results soon. If it is confirmed, the standard model may need a revamp, even if the Higgs is discovered to fit neatly into it.

Reference: arxiv.org/abs/arXiv:1205.5442

Read more: www.newscientist.com

Written by physicsgg

June 20, 2012 at 6:36 am

Posted in High Energy Physics

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Higgs News ?!

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I hope my colleagues will pardon me if I just point you readers here to a site which has many more readers anyway, where Peter Woit is distributing a rumor about ATLAS and CMS having both observation-level signals in their data. I am unable to comment (yet), but of course if the rumor is true then in the next few days we will have reasons to party !

The only thing I think I can discuss with you here now is the predictions on the Higgs boson significance level produced by CMS in October 2010 – a couple of geological eras ago, that is. Those predictions can be trusted because 2011 data showed to be perfectly in line with them, both for the 95% CL limits and for the significance -of course the former are valid in the full mass range and provide more verification power than the single significance number, which is only valid if the Higgs boson exists and has a particular mass…..

Read more: www.science20.com

Written by physicsgg

June 17, 2012 at 2:19 pm

Posted in High Energy Physics

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Why the Higgs particle hunt was always going to be a waiting game

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What does it mean to know something? As the experiments at Cern continue to show, it means testing a theory to destruction

The Large Hadron Collider at Cern, where scientists continue their hunt for the Higgs particle. Photograph: Mark Thiessen/National Geographic Society/Corbis

Jeff Forshaw
Two beams of protons circulate around the 27km circumference of the Large Hadron Collider tunnel under the Franco-Swiss border. Those protons moving clockwise collide, head on, with those moving anticlockwise and the collisions take place in the middle of cavernous detectors. The scientists working on two of these detectors have made it their immediate priority to find the much vaunted Higgs particle and, towards the end of last year, the first, tentative, evidence of the particle’s existence was made public. Next month, at an international conference in Australia, we can expect to hear the latest news on the hunt. The burning question is whether, with more data, the experimental evidence will strengthen or weaken. So what is the evidence and why do we need to keep waiting on tenterhooks?

When two protons crash into each other they break up, producing hundreds more particles that spray out in all directions, like an exploding firework. The huge detectors are designed to capture the debris and provide a snapshot of the collision…..
Read more: www.guardian.co.uk

Written by physicsgg

June 17, 2012 at 6:31 am

Posted in High Energy Physics

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Is the moon full? Just ask the LHC operators

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Last weekend, I had the pleasure to be shift leader for ATLAS. It was a real pleasure for many reasons: being right in the middle of the action, surrounded by an international team of enthusiastic and dedicated people, and taking part in great teamwork. The shift crew (about ten people plus dozens of experts on call) must keep the detector running smoothly, tackling every problem, big or small, as fast as possible.

Data was coming in at a high rate and all sub-detectors were humming nicely. Not a glitch in hours so we were getting slightly sleepy nearing the end of the shift around 22:00. So when a colleague from the trigger system (the system that decides which events are worth keeping) called to inquire about recurrent splashes of data, I was rather puzzled.

I quickly went around, asking a few shifters to check their system. Nobody had a clue. Then I took a closer look at this plot that I had not scrutinized before since everything was so seamless.

The two lower curves in beige and green show the instantaneous luminosity measured by the two largest detectors operating on the Large Hadron Collider (LHC), CMS andATLAS. This is a measure of how many collisions are happening per second in each experiment from the two beams of protons circulating in opposite direction in the LHC tunnel. If you look closely at these curves, they both have small dips at regular intervals. Since both ATLAS and CMS were registering these dips, it had to be coming from a common source, the LHC.

So I called the LHC control room to find out what was happening. “Oh, those dips?”, casually answered the operator on shift. “That’s because the moon is nearly full and I periodically have to adjust the proton beam orbits.”

This effect has been known since the LEP days, the Large Electron Positron collider, the LHC predecessor. The LHC reuses the same circular tunnel as LEP. Twenty some years ago, it then came as a surprise that, given the 27 km circumference of the accelerator, the gravitational force exerted by the moon on one side is not the same as the one felt at the opposite side, creating a small distortion of the tunnel. Since the moon’s effect is very small, only large bodies like oceans feel its effect in the form of tides. But the LHC is such a sensitive apparatus, it can detect the minute deformations created by the small differences in the gravitational force across its diameter. The effect is of course largest when the moon is full.

What came as a surprise to me was to witness the dynamic aspect of it. As the moon was rising in the sky, the force it exerted changed ever so slightly, but even these infinitesimal changes were big enough to require a periodic correction of the orbit of the proton beams in the accelerator to adapt to a deformed tunnel.

Other surprising disturbances were also observed in the LEP days like one that appeared every day at fixed times. It took months and a train company strike to figure it out. These perturbations were created by the passage of the fast train linking Geneva to Paris, the TGV, since it releases a lot of electrical energy into the ground.

The LHC is also sensitive to the hydrostatic pressure created by the water level in nearby Lake Geneva that also deforms the tunnel shape.

So next time you want to know if the moon is full, just check the luminosity plot from the LHC to see if you can spot those small glitches caused by the operator correcting the beam orbit. (The header will have to read “Proton physics: stable beams” to see these curves).
Pauline Gagnon
Read more: www.quantumdiaries.org

Written by physicsgg

June 8, 2012 at 12:55 pm

Posted in High Energy Physics

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New CERN Results On Rare B Decays

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A Tombstone To SUSY ?

 The CERN average of searches for rare B decays to muon pairs has been shown yesterday in a talk given by Mitesh Patel at the “Physics at the LHC” conference, which is being held in Vancouver (BC) this week. And the results are not very encouraging for supporters of Supersymmetry: the data is compatible with a Standard Model signal, but there is almost no space left for additional contributions due to the exchange of virtual SUSY particles in the loops producing the decays……
Read more:www.science20.com

Written by physicsgg

June 8, 2012 at 12:50 pm

Posted in High Energy Physics

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The ATLAS detector on a smartphone

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About LHsee
LHsee is an educational tool available for Android OS mobile smartphones and tablet PCs. It has been custom designed to provide an accurate and interactive visual representation of complex high-energy physics events recorded by the ATLAS detector. Features include live streaming and reconstruction of collision data from the CERN Large Hadron Collider.

The Large Hadron Collider (LHC) at CERN is one of the most inspirational science projects of our time. The machine has been designed to address fundamental questions about the nature of our universe, including the origin of mass, the difference between matter and antimatter and evidence for grand unified theories. The experiment has captured the public imagination and offers an unparalleled oppor tun ity to explain science to a wide r ange of audiences.
Even before the first operations of the LHC (in September 2008) a variety of introductory and educational resources had been produced [1]. Modern mobile smartphones (and tablet PCs) offer a new and highly capable platform for science education.
Such devices typically include 3G/WiFi internet access, dedicated graphics hardware and touchscreen control….

Read more:iopscience.iop.org

Written by physicsgg

May 30, 2012 at 8:51 pm

Posted in High Energy Physics

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What would happen if you put your hand in the Large Hadron Collider?

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Written by physicsgg

May 3, 2012 at 1:42 pm

Posted in High Energy Physics, HUMOR

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Is it possible to create a quantum electromagnetic “black hole” at the LHC?

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Numerical simulations of the extraordinary electromagnetic field distribution
in the vicinity of the electromagnetic “event horizon” located at z=0

Igor I. Smolyaninov
As demonstrated by Chernodub, strong magnetic field forces vacuum to develop real condensates of electrically charged rho mesons, which form an anisotropic inhomogeneous superconducting state similar to Abrikosov vortex lattice. As far as electromagnetic field behaviour is concerned, this state of vacuum constitutes a hyperbolic metamaterial [1]. Here we demonstrate that spatial variations of magnetic field may lead to formation of electromagnetic “black holes” inside this metamaterial. Similar to real black holes, horizon area of the electromagnetic “black holes” is quantized in units of the effective “Planck scale” squared. The magnetic fields of the required strength and geometrical configuration may be created on Earth in heavy-ion collisions at the Large Hadron Collider. We evaluate electromagnetic field distribution around an electromagnetic “black hole” which may be created as a result of such collision….
Read more: arxiv.org/ftp/arxiv/pdf

Written by physicsgg

April 7, 2012 at 4:43 pm

Posted in High Energy Physics

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