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  • richardmitnick 11:58 am on October 30, 2014 Permalink | Reply
    Tags: , CERN, , , , ,   

    From LC Newsline: “The future of Higgs physics” 

    Linear Collider Collaboration header
    Linear Collider Collaboration

    30 October 2014
    Joykrit Mitra

    In 2012, the ATLAS and CMS experiments at CERN’s Large Hadron Collider announced the discovery of the Higgs boson. The Higgs was expected to be the final piece of the particular jigsaw that is the Standard Model of particle physics, and its discovery was a monumental event.

    Event recorded with the CMS detector in 2012 at a proton-proton centre of mass energy of 8 TeV. The event shows characteristics expected from the decay of the SM Higgs boson to a pair of photons (dashed yellow lines and green towers). Image: L. Taylor, CMS collaboration /CERN

    The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.


    CERN CMS New

    But more precise studies of it are needed than the LHC is able to provide. That is why, years earlier, a machine like the International Linear Collider had been envisioned as a Higgs factory, and the Higgs discovery set the stage for its possible construction.

    ILC schematic
    ILC schematic

    Over the years, instruments for probing the universe have become more sophisticated. More refined data has hinted that aspects of the Standard Model are incomplete. If built, a machine such as the ILC will help reveal how wide a gulf there is between the universe and our understanding of it by probing the Higgs to unprecedented levels. And perhaps, as some physicists think, it will uproot the Standard Model and make way for an entirely new physics.

    In the textbook version, the Higgs boson is a single particle, and its alleged progenitor, the mysterious Higgs field that pervades every point in the universe, is a single field. But this theory is still to be tested.

    “We don’t know whether the Higgs field is one field or many fields,” said Michael Peskin of SLAC’s Theoretical Physics Group. “We’re just now scratching the surface at the LHC.”

    The LHC collides proton beams together, and the collision environment is not a clean one. Protons are made up of quarks and gluons, and in an LHC collision it’s really these many component parts – not the larger proton – that interact. During a collision, there are simply too many components in the mix to determine the initial energies of each one. Without knowing them, it’s not possible to precisely calculate properties of the particles generated from the collision. Furthermore, Higgs events at the LHC are exceptionally rare, and there is so much background that the amount of data that scientists have to sift through to glean information on the Higgs is astronomical.

    “There are many ways to produce an event that looks like the Higgs at the LHC,” Peskin said. “Lots of other things happen that look exactly like what you’re trying to find.”

    The ILC, on the other hand, would collide electrons and positrons, which are themselves fundamental particles. They have no component parts. Scientists would know their precise initial energy states and there will be significantly fewer distractions from the measurement standpoint. The ILC is designed to be able to accelerate particle beams up to energies of 250 billion electronvolts, extendable eventually to 500 billion electronvolts. The higher the particles’ energies, the larger will be the number of Higgs events. It’s the best possible scenario to probe the Higgs.

    If the ILC is built, physicists will first want to test whether the Higgs particle discovered at the LHC indeed has the properties predicted by the Standard Model. To do this, they plan to study Higgs couplings with known subatomic particles. The higher a particle’s mass, the proportionally stronger its coupling ought to be with the Higgs boson. The ILC will be sensitive enough to detect and accurately measure Higgs couplings with light particles, for instance with charm quarks. Such a coupling can be detected at the LHC in principle but is very difficult to measure accurately.

    The ILC can also help measure the exact lifetime of the Higgs boson. The more particles the Higgs couples to, the faster it decays and disappears. A difference between the measured lifetime and the projected lifetime—calculated from the Standard Model—could reveal what fraction of possible particles—or the Higgs’ interactions with them— we’ve actually discovered.

    “Maybe the Higgs interacts with something new that is very hard to detect at a hadron collider, for example if it cannot be observed directly, like neutrinos,” speculated John Campbell of Fermilab’s Theoretical Physics Department.

    These investigations could yield some surprises. Unexpected vagaries in measurement could point to yet undiscovered particles, which in turn would indicate that the Standard Model is incomplete. The Standard Model also has predictions for the coupling between two Higgs bosons, and physicists hope to study this as well to check if there are indeed multiple kinds of Higgs particles.

    “It could be that the Higgs boson is only a part of the story, and it has explained what’s happened at colliders so far,” Campbell said. “The self-coupling of the Higgs is there in the Standard Model to make it self-consistent. If not the Higgs, then some other thing has to play that role that self-couplings play in the model. Other explanations could also provide dark matter candidates, but it’s all speculation at this point.”

    3D plot showing how dark matter distribution in our universe has grown clumpier over time. (Image: NASA, ESA, R. Massey from California Institute of Technology)

    The Standard Model has been very self-consistent so far, but some physicists think it isn’t entirely valid. It ignores the universe’s
    accelerating expansion caused by dark energy, as well as the mysterious dark matter that still allows matter to clump together and galaxies to form. There is speculation about the existence of undiscovered mediator particles that might be exchanged between dark matter and the Higgs field. The Higgs particle could be a likely gateway to this unknown physics.

    With the LHC set to be operational again next year, an optimistic possibility is that a new particle or two might be dredged out from trillions of collision events in the near future. If built, the ILC would be able to build on such discoveries, just as in case of the Higgs boson, and provide a platform for more precise investigation.

    The collaboration between a hadron collider like the LHC and an electron-positron collider of the scale of the ILC could uncover new territories to be explored and help map them with precision, making particle physics that much richer.

    See the full article here.

    The Linear Collider Collaboration is an organisation that brings the two most likely candidates, the Compact Linear Collider Study (CLIC) and the International Liner Collider (ILC), together under one roof. Headed by former LHC Project Manager Lyn Evans, it strives to coordinate the research and development work that is being done for accelerators and detectors around the world and to take the project linear collider to the next step: a decision that it will be built, and where.

    Some 2000 scientists – particle physicists, accelerator physicists, engineers – are involved in the ILC or in CLIC, and often in both projects. They work on state-of-the-art detector technologies, new acceleration techniques, the civil engineering aspect of building a straight tunnel of at least 30 kilometres in length, a reliable cost estimate and many more aspects that projects of this scale require. The Linear Collider Collaboration ensures that synergies between the two friendly competitors are used to the maximum.

    Linear Collider Colaboration Banner

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  • richardmitnick 2:33 pm on October 13, 2014 Permalink | Reply
    Tags: CERN,   

    From CERN via FNAL: “CERN and the rise of the Standard Model” 

    CERN New Masthead

    Curiosity is as old as humankind, and it is CERN’s raison d’être. When the Laboratory was founded, the structure of matter was a mystery. Today, we know that all visible matter in the Universe is composed of a remarkably small number of particles, whose behaviour is governed by four distinct forces. CERN has played a vital role in reaching this understanding.

    Watch, enjoy, learn.

    Meet CERN in a variety of places:

    Cern Courier



    CERN CMS New

    CERN LHCb New


    CERN LHC New

    LHC particles

    Quantum Diaries

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  • richardmitnick 2:42 pm on August 23, 2014 Permalink | Reply
    Tags: , , CERN, , , , , U-70 Synchrotron   

    From ExtremeTech via Fermilab: “What happens if you get hit by the main beam of a particle accelerator like the LHC?” 

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    July 28, 2014
    Sebastian Anthony


    I don’t know about you, but ever since I started covering the Large Hadron Collider and other large-scale particle accelerators for ExtremeTech, I’ve always morbidly wondered: What would happen if a scientist was accidentally hit by the main particle beam? Would the scientist explode in the style of beam weapons in Star Trek? Would the beam bore a hole clean through the scientist’s chest? Or maybe the beam would do nothing at all and pass through the scientist harmlessly? Well, fortunately (unfortunately?) we don’t have to guess, as this exact scenario actually happened to Anatoli Bugorski, a Russian scientist, way back in 1978.

    Back in the 1970s, Anatoli Bugorski was a researcher at the Soviet Union’s Institute for High Energy Physics. The Institute housed the U-70, a synchrotron that when it was built was the most powerful particle accelerator in the world (it’s still the most powerful accelerator in Russia today). The U-70 smashes two beams of protons together at a combined energy of around 76 GeV, at a speed that gets very close to the speed of light.



    On July 13, 1978, Bugorski was checking a malfunction on the U-70… and then somehow his head ended up in the path of the main proton beam. The beam entered his skull on the back left, and came out near the left side of his nose. Sources seem to disagree on how much ionizing radiation Bugorski actually took to the head, but some say it was as high as 2,000-3,000 grays (200,000-300,000 rads). In any case, the beam would’ve been more than strong enough to burn a hole through the bone, skin, and brain tissue.

    At the time, Bugorski reported seeing a flash that was “brighter than a thousand suns,” but otherwise didn’t feel any pain. Over the next few days, the left side of his head swelled up “beyond recognition,” and then his skin started peeling off. Bugorski was moved to Moscow, where doctors avidly observed his expected demise — but, curiously enough, he survived. The left side of his face is paralyzed (due to nerve damage), his left ear is shot (all he can hear is an “unpleasant internal noise”), and he occasionally suffers from seizures, but otherwise Bugorski was relatively unscathed by the accident. He went on to complete his PhD — and he’s still alive today.
    Inside the Russian U-70 synchrotron building, in 2006

    U-70 synchrotron, diagram

    Anatoli Bugorski today.

    You can see that the left side of his face droops a bit from the paralysis, and that it’s wrinkle-free because he hasn’t been able to move it for 26 years — similar to how Botox works, in actual fact.

    Slightly anticlimactic, eh? Well, if it’s any consolation, Bugorski probably got incredibly lucky that the proton beam (apparently) missed any vital parts of his brain. If it had hit the hippocampus, motor cortex, or the frontal lobe, this story wouldn’t have had a very happy ending. Likewise, it’s probably lucky that the beam hit his brain — which has the remarkable ability to rewire itself when such disasters occur — rather than some other vital organ. If the beam had sliced through his heart, or an artery in his neck, he probably would’ve died instantly.

    It’s also important to note that the beam from a particle accelerator is very narrow (the more focused the beam is, the higher the chance of collisions with protons in the other beam). As you can see in the black and white photo above, only a small patch of hair is missing from Bugorski’s scalp, suggesting the beam only fried quite a narrow channel of brain tissue. In much the same way that you could pass a very thin hypodermic needle through someone without causing too much damage, a particle beam probably isn’t going to carve a comically large cylinder through the victim’s chest.

    XKCD’s radiation dose chart. A sievert (Sv) is a measure of absorbed radiation; grays (Gy) are a physical quantity of radiation. Bugorski was hit by a large number of grays, but seemingly didn’t absorb much of it.

    A dosage of between 2,000 and 3,000 grays, if it was effectively absorbed by the human body (i.e. sieverts), would usually be more than enough to cause acute radiation sickness and death. In this case, though, the beam was so focused that it just passed straight through his body; if it had been more scattered, and fried a wider smattering of cells, Bugorski would certainly have died.

    The LHC’s CMS detector. If the main beam was turned on, would the hard-hatted engineer be blown to smithereens?

    Finally, though, it’s worth noting that the Russian U-70 is a very weak particle accelerator by today’s standards. When the Large Hadron Collider comes back online in 2015, it’ll have a proton-proton collision energy of around 14 TeV — or about 200 times more power than the U-70′s 67 GeV. Despite its high energy, though, we’re still only talking about a beam of protons that’s a few millimeters wide — and of course there are all sorts of security measures that would prevent a CERN scientist from ever being hit by the LHC’s main beam. If those safety mechanisms failed, and the superconducting magnets that keep the beam focused and on target were on the fritz, then maybe you’d end up with a proton beam that moved around enough to slice a scientist into pieces. It’s a long shot, though.

    See the full article here.

    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics.

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  • richardmitnick 12:13 pm on August 19, 2014 Permalink | Reply
    Tags: , , CERN, ,   

    From CERN Courier: “First direct high-precision measurement of the proton’s magnetic moment sets the stage for BASE” 

    CERN Courier

    Jul 23, 2014
    No Writer Credit

    A German/Japanese collaboration working at the University of Mainz has performed the first direct high-precision measurement of the magnetic moment of the proton – which is by far the most accurate to date.

    The quark structure of the proton. (The color assignment of individual quarks is not important, only that all three colors are present.)

    The result is consistent with the currently accepted value of the Committee on Data for Science and Technology (CODATA), but is 2.5 times more precise and 760 times more accurate than any previous direct measurement. The techniques used will feature in the Baryon-Antibaryon Symmetry Experiment (BASE) – recently approved to run at CERN’s Antiproton Decelerator (AD) – which aims at the direct high-precision measurement of the magnetic moments of the proton and the antiproton with fractional precisions at the parts-per-billion (ppb) level, or better.

    The quark structure of the antiproton.

    CERN Antiproton Decelerator
    CERN Antiproton Decelerator

    Prior to this work, the record for the most precise measurement of the proton’s magnetic moment had stood for more than 40 years. In 1972, a group at Massachusetts Institute of Technology measured its value indirectly by performing ground-state hyperfine spectroscopy with a hydrogen maser in a magnetic field. This experiment measured the ratio of the magnetic moments of the proton and the electron. The results, combined with theoretical corrections and two additional independent measurements, enabled the calculation of the proton magnetic moment with a precision of about 10 parts in a billion.

    Hydrogen maser. (Courtesy NASA/JPL-Caltech)

    In an attempt to surpass the record, the collaboration of scientists from Mainz University, the Max Planck Institute for Nuclear Physics in Heidelberg, GSI Darmstadt and the Japanese RIKEN institute applied the so-called double Penning trap technique to a single proton for the first time (see figure 1).


    One Penning trap – called the analysis trap – is used for the non-destructive detection of the spin state, through the continuous Stern-Gerlach effect. In this elegant approach, a strong magnetic inhomogeneity is superimposed on the trap, so coupling the particle’s spin-magnetic-moment to its axial oscillation frequency in the trap. By measuring the axial frequency, the spin quantum state of the trapped particle can be determined. And by recording the quantum-jump rate as a function of a spin-flip drive frequency, the spin precession frequency νL is obtained. Together with a measurement of the cyclotron frequency νc of the trapped particle, the magnetic moment of the proton μp is obtained finally in units of the nuclear magneton, μp/μN = νL/νc.

    Fig. 2.

    This approach has already been applied with great success in measurements of the magnetic moments of the electron and the positron. However, the magnetic moment of the proton is about 660 times smaller than that of the electron, so the proton measurement requires an apparatus that is orders of magnitude more sensitive. To detect the proton’s spin state, the collaboration used an extremely strong magnetic inhomogeneity of 300,000 T/m2. However, this limits the experimental precision in the frequency measurements to the parts-per-million (ppm) level. Therefore a second trap – the precision trap – was added about 45 mm away from the strong magnetic-field inhomogeneity. In this trap the magnetic field is about 75,000 times more homogeneous than in the analysis trap.

    To determine the magnetic moment of the proton, the first step was to identify the spin state of the single particle in the analysis trap. Afterwards the particle was transported to the precision trap, where the cyclotron frequency was measured and a spin flip induced. Subsequently the particle was transported back to the analysis trap and the spin state was analysed again. By repeating this procedure several hundred times, the magnetic moment was measured in the homogeneous magnetic field of the precision trap. The result, extracted from the normalized resonance curve (figure 2), is the value μp = 2.792847350(9)μN, with a relative precision of 3.3 ppb.

    In the BASE experiment at the AD the technique will be applied directly to a single trapped antiproton and will potentially improve the currently accepted value of the magnetic moment by at least a factor of 1000. This will constitute a stringent test with baryons of CPT symmetry – the most fundamental symmetry underlying the quantum field theories of the Standard Model of particle physics. CPT invariance implies the exact equality of the properties of matter–antimatter conjugates and any measured difference could contribute to understanding the striking imbalance of matter and antimatter observed on cosmological scales.

    See the full article here.

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  • richardmitnick 12:14 pm on August 15, 2014 Permalink | Reply
    Tags: , CERN, , ,   

    From BBC: “Higgs boson spills secrets as LHC prepared for return” 


    30 June 2014
    Paul Rincon

    It’s nearly time. After shutting down last year for vital repairs and upgrades, the Large Hadron Collider is being prepared for its comeback.

    CERN LHC Map
    Map of th LHC at CERN

    LHC Tube
    LHC tube in its tunnel

    Engineers at Cern in Geneva have begun cooling the huge machine to its operating temperature of -271.3C, which is colder than deep space.

    And the accelerator system that supplies the LHC with its proton particle beams – which are smashed together to recreate the conditions just after the Big Bang – is up and running for the first time since 2012.

    Teams are working to get the LHC – located in a circular tunnel beneath the French-Swiss border – back online by January 2015 and this time it will operate at its full energy of 14 trillion electron volts.

    After the $10bn machine was switched on for the first time in 2008, problems were found with many of the electrical splices between the 1,200 superconducting magnets that bend particle beams around the 27km-long underground ring.

    To prevent serious damage, officials decided to run the collider at an energy of seven to eight trillion electron volts – about half what it was designed for.

    “Much work has been carried out on the LHC over the last 18 months or so, and it’s effectively a new machine, poised to set us on the path to new discoveries,” said Cern’s director-general Rolf Heuer at the EuroScience Open Forum in Copenhagen this month.

    The Higgs is a sub-atomic particle that was detected at the Large Hadron Collider in 2012
    It was proposed as a mechanism to explain mass by six physicists, including Peter Higgs, in 1964
    It imparts mass to other fundamental particles via the associated Higgs field
    It is the cornerstone of the Standard Model, which explains how particles interact

    The low energy run from 2010-2012 was nevertheless sufficient to achieve a key scientific goal: Detecting the elusive Higgs boson particle.

    The Higgs is the cornerstone of our current best theory of particle physics – the Standard Model. This is the “instruction booklet” that describes how elementary particles (the smallest building blocks of the Universe) and forces interact.

    The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    On 4 July 2012, Cern announced that a five-decade-long search for the particle, first proposed by Edinburgh-based physicist Peter Higgs and others in the 1960s, had reached its conclusion.

    Scientists working on Atlas and CMS, the two huge multi-purpose detectors placed at strategic points around the LHC tunnel, saw the Higgs at a 5-sigma level of significance – the statistical threshold for announcing a discovery.


    CERN CMS New

    Particle physicists have learnt more about the Higgs boson’s behaviour and how well it conforms to predictions. In a paper published in the journal Nature Physics, researchers outlined how they have watched the Higgs decay into the particles that make up matter (known as fermions), in addition to those that convey force (bosons), which had already been observed.

    This is exactly as the Standard Model predicts. Physicists know that this framework, devised in the 1970s, must be a stepping stone to a deeper understanding of the cosmos. But so far, it’s standing up exceptionally well. Searches at the LHC for deviations from this elegant scheme – such as evidence for new, exotic particles – have come to nothing.

    Higgs update, 2012 Physicists packed out the auditorium at Cern to hear the Higgs boson discovery announcement in 2012

    Higgs update, 2012 Francois Englert (L), Peter Higgs (R) and other originators of the Higgs boson theory were at Cern to hear the announcement. Englert and Higgs would later win a Nobel Prize for their work

    Higgs update, 2012 The announcement was a huge media event too

    At ICHEP, other scientists are expected to outline details of a refined mass for the fundamental particle, which has been measured at approximately 125 gigaelectronvolts (GeV). For those outside the particle physics community, this might seem like a minor detail. But the mass of the Higgs is more than a mere number.

    There’s something very curious about its value that could have profound implications for the Universe. Mathematical models allow for the possibility that our cosmos is long-lived yet not entirely stable, and may – at some indeterminate point – be destroyed.

    “The overall stability of the Universe depends on the Higgs mass – which is a bit funny,” said Prof Jordan Nash, a particle physicist from Imperial College London, who works on the CMS experiment at Cern.

    “There’s a long theoretical argument which I won’t go into, but that value is intriguing in that it sits on the edge between what we think is the long-term stability of the Universe and a Universe that has a finite lifetime.”

    To use an analogy, imagine the Higgs boson is an object resting at the bottom of a curved slope. If that resting place really is the lowest point on the slope, then the vacuum of space is completely stable – in other words, it is in the lowest energy state and can go no further.
    Infographic The mass of the Higgs (inside rectangle) may hint at the stability of the Universe

    However, if at some point further along this slope, there’s another dip, the potential exists for the Universe to “topple” into this lower energy state, or minimum. If that happens, the vacuum of space collapses, dooming the cosmos.

    “The Higgs mass is in that place where it gets interesting, where it’s no longer guaranteed that there are no other minima,” Prof Nash, who works on the CMS experiment at Cern, told the BBC. But there’s no need to worry, the models suggest such a rare event would not occur for a very, very long time – many times further into the future, in fact, than the current age of the Universe.

    This idea of a finite lifetime for the cosmos is dependent on the Standard Model being the ultimate scheme in physics. But there is much in the Universe – gravitation and dark matter, for example – that the Standard Model can’t fully explain, so there are reasons to think that’s not the case.

    The existence of exotic particles, such as those predicted by the theory known as supersymmetry, would shore up the stability of the Universe in those mathematical models.

    Supersymmetry standard model

    But as previously mentioned, searches for these particles, called superpartners, have so far drawn a blank, as have attempts to detect dark matter, extra dimensions, and other phenomena beyond the Standard Model. Hopes that the LHC would allow scientists to lift the veil on a whole new realm of physics have proved optimistic, at least during its initial run.

    Re-soldering Electrical connections between the superconducting magnets have been re-soldered

    Work in tunnel Engineers have been working to prepare the machine for a planned re-start at the beginning of 2015

    Some versions of supersymmetry have already been all but ruled out by the LHC. But the theory has many forms, depending on how you tweak the mathematical parameters.

    “From the theory community’s point of view, this is all very interesting because it fleshes out much better what the first run of the LHC has excluded,” said Prof Dave Charlton, who leads the Atlas experiment at Cern.

    “Therefore, it better establishes where we should be looking for new signals next year.”

    Assuming the theorists are indeed correct, supersymmetry will have to wait some time longer for its big reveal.

    Other hypothesised particles, such as the W prime and Z prime bosons could possibly be detected soon after the LHC returns to particle smashing.

    For now, all eyes are on the engineers at Cern. The LHC’s initial switch on was marked by mishaps, including a magnet that buckled in the tunnel during a test in 2007. The following year, another magnet failure caused a tonne of helium to leak out, forcing controllers to shut the machine down just nine days after its big switch-on.

    But after the re-start in 2009, the LHC performed flawlessly, and the rest, as they say, is history.

    If all goes well, by the end of March 2015 scientists could begin colliding high-energy beams of particles at the LHC.

    And that’s when the real fun will begin.

    See the full article here.

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  • richardmitnick 11:28 am on August 15, 2014 Permalink | Reply
    Tags: , , CERN, , , ,   

    Brian Cox on the LHC 

    Published on Dec 8, 2012

    A great video, a bit dated, by our freind Brian Cox

    “Rock-star physicist” Brian Cox talks about his work on the Large Hadron Collider at CERN. Discussing the biggest of big science in an engaging and accessible way, Cox brings us along on a tour of the massive project.

    Watch, enjoy and learn.

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  • richardmitnick 2:47 pm on August 1, 2014 Permalink | Reply
    Tags: , , CERN, , , , ,   

    From Symmetry: “Using the Higgs boson to search for clues” 


    August 01, 2014
    Sarah Charley

    After a new particle such as the Higgs boson is discovered, scientists want to measure all of its properties as accurately as possible. Not only does this help determine how it fits into our greater understanding of matter, but it can also provide hints of what we don’t yet know.

    “To some people, the discovery of the Higgs completed everything,” says Colin Jessop, a professor of physics at the University of Notre Dame. “But to particle physicists, it is the beginning of everything.”

    Historically, precision measurements of known particles have yielded priceless information. In the 1960s and ’70s, for example, scientists from SLAC National Accelerator Laboratory and the Massachusetts Institute of Technology proved the existence of quarks, fundamental particles that make up protons

    The quark structure of the proton. (The color assignment of individual quarks is not important, only that all three colors are present.)

    and neutrons,

    The quark structure of the neutron. (The color assignment of individual quarks is not important, only that all three colors are present.)

    by making precise measurements of protons. More recently, scientists at Fermi National Accelerator Laboratory

    Fermilab Tevatron
    Fermilab Tevatron map

    and CERN carefully measured the mass of the heaviest of the quarks, the top quark,

    A collision event involving top quarks

    and the W boson, a particle that carries the force that mediates atomic decay, to help them estimate the mass of the then-undiscovered Higgs boson.

    Now, scientists at the Large Hadron Collider are hoping that precision measurements of the Higgs boson will help them solve the next big mysteries, such as the origin of dark matter.

    LHC Tube
    LHC Tube

    CERN LHC Map
    LHC map

    “The reason we proposed the concept of dark matter is because we cannot explain the total mass of the universe,” says Swagato Banerjee, a postdoc at the University of Wisconsin. “And the only way we know how fundamental particles acquire mass is through the Higgs mechanism. So if dark matter is fundamental, it has to interact with the Higgs to acquire mass, at least in our known framework.”

    When the Higgs is produced at the LHC, it quickly decays into lighter, more stable particles. If the Higgs interacts with dark matter, then it should be able to decay into dark matter. Currently LHC scientists are studying all the possible ways the Higgs can decay into other particles to search for any unexplained decays that could be hints of something new, like dark matter.
    Hunting for new processes

    If scientists find that the Higgs does something unexpected, it could be a clue that we don’t yet grasp the full picture, says Maria Cepeda Hermida, a postdoc at the University of Wisconsin.

    “If you only look for what you think exists, then you could miss something important,” Cepeda says. “We have to look outside of the box for what we don’t expect to see if there are any new surprises.”

    Cepeda is involved in a study that searches for evidence of the Higgs boson disobeying the well-defined laws of the Standard Model of particle physics. Recent studies from the CMS and ATLAS experiments at the LHC showed that the Higgs boson decays directly to particles of matter, some of which have a special characteristic called flavor.

    The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    CERN CMS New


    The family of matter particles called leptons is made up of particles of three flavo[u]rs: electron, muon and tau. Because the Higgs boson has no associated flavor, the Standard Model predicts that the sum of its decay products will also have no flavor. A particle of a certain flavor and its antiparticle will cancel one another out.

    Cepeda is part of an analysis group Jessop leads that is looking for evidence of the Higgs breaking this rule by decaying to two particles of different flavors, namely, a tau and a muon.

    The preliminary results from this study restrict the likelihood of this process enormously—down to less than three out of every 200 decays. But it cannot rule it out entirely. In fact, scientists saw a small deviation from their predictions, which is either the result of normal statistical fluctuation or the first glimpse of a new process.

    If scientists find that the Higgs can break the laws of flavor, it would help explain why fundamental particles come in a variety of masses.

    “We see families of particles that are identical except in their mass,” says Roni Harnik, a theorist at Fermilab. “So what mechanism ‘decides’ that the tau is much heavier than the muon, who in turn is much heavier than the electron? In the Standard Model, it is the Higgs alone.”

    Evidence for this process would also open up many other possibilities, Harnik says.

    “Seeing this decay would teach us something profound: that the Higgs boson is not the exclusive source of mass in the universe, and that we have more interesting things to discover.”
    A mystery in itself

    The Higgs boson may be physicists’ best tool to look for new particles because the Standard Model predicts that it interacts with everything that has mass. But the Higgs itself still holds many mysteries. For instance, the mass of the Higgs is precariously perched between two stable zones predicted by the Standard Model.

    “If there is just the Standard Model Higgs and nothing else, then the mass of the Higgs boson is theoretically unstable,” says Hideki Okawa, a postdoc at Brookhaven National Laboratory. “Many people think that there should be something else that stabilizes the Higgs mass.”

    The Higgs is also an entirely unique particle and unlike anything else ever observed by scientists. So the question remains: Is the Higgs alone? Or are there others?

    “We think there could be more Higgs bosons,” Okawa says. “This would make the theory more natural.”

    The restart of the LHC in early 2015 will give scientists more data to probe the properties of the Higgs boson even further and search for new physics or phenomena just out of reach.

    “Finding the Higgs opens more questions than it answers,” Banerjee says. “But it also focuses the questions we had before its discovery.”

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.

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  • richardmitnick 10:57 am on July 14, 2014 Permalink | Reply
    Tags: , , , CERN, , , ,   

    From Test4Theory: ” Server migration completed” 

    LHC@home 2dot0


    The migration of Test4Theory to the new vLHC@home server is completed. In case of problems, we advice to detach and re-attach to the project.

    Thanks for your understanding and for your contributions!

    See the full article here.


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  • richardmitnick 7:35 pm on July 13, 2014 Permalink | Reply
    Tags: , CERN, Test4Theory   

    From LHC Test4Theory: “Migration to new server and change of project name” 

    LHC@home 2dot0


    On Monday July 14, the Test4theory project will be migrated to a new server, and also get a new name: “vLHC@home”.

    Following 3 years of running Theory simulations under CernVM and BOINC, we plan to gradually expand the project and add more applications on CernVM with simulations from the LHC experiments. Thus the new name: “Virtual LHC@home”.

    The old server URL will be redirected, and we expect that the transition should be transparent to BOINC clients. The forums and BOINC user database with accumulated credit will remain the same as today. There is a slight risk that running tasks may fail and that the credit for these will be lost. We would in that case recommend to detach and re-attach to the project. Further advice will be given here in the News forum once the upgrade is completed.

    We would like to express our warmest thanks to all of you for your contributions to Test4Theory, and hope that you will continue to stay with us in the future!

    The team

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  • richardmitnick 1:16 pm on June 12, 2014 Permalink | Reply
    Tags: , , CERN, , , , , ,   

    From Symmetry: “Researchers imagine the accelerators of the future” 


    June 12, 2014
    Sarah Charley

    At the LHC Physics Conference in New York, experts looked to the next steps in collider physics.

    In the late 1800s, many scientists thought that the major laws of physics had been discovered—that all that remained to be resolved were a few minor details.

    Then in 1896 came the discovery of the first fundamental particle, the electron, followed by the discovery of atomic nuclei and revolutions in quantum physics and relativity. Modern particle physics had just begun, said Natalie Roe, the Director of the Physics Division at Lawrence Berkeley National Laboratory, at the recent Large Hadron Collider Physics Conference in New York.

    Since then, physicists have discovered a slew of new elementary particles and have developed a model that accurately describes the fundamental components of matter. But this time, they know that there is more left to find—if only they can reach it. In a presentation and a panel discussion chaired by New York Times science reporter Dennis Overbye, experts at the LHCP Conference discussed the future of collider-based particle physics research.

    The discovery of a Higgs boson bolstered physicists’ confidence in the Standard Model—our best understanding of matter at its most fundamental level. But the Standard Model does not answer important questions such as why the Higgs boson is so light or why neutrinos have mass, nor does it account for dark matter and dark energy, which astronomical observations indicate make up the majority of the known universe.

    The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    “We know that the Standard Model is not a complete theory because many outstanding questions remain,” said CERN physicist Fabiola Gianotti, the former head of the ATLAS experiment at the LHC, at the LHCP Conference. “We must ask, at what energy scales do these questions find their answers?”

    ATLAS at the LHC

    CERN LHC Grand Tunnel

    CERN LHC Map
    LHC at CERN

    The LHC will access an energy level higher than any previous accelerator, up to 13 trillion electronvolts, when it restarts in 2015. Scientists are already thinking about what could come next, such as the proposed International Linear Collider or hadron colliders under discussion in Europe and Asia.

    ILC schematic
    ILC design

    CLIC design at CERN

    Building any proposed future accelerator will not be easy, “and none of them are cheap,” Gianotti said. However, one should not discount the opportunities that technological advances can afford.

    Gianotti pointed out that, in a 1954 presentation to the American Physical Society, Nobel Laureate Enrico Fermi estimated that an accelerator capable of accessing up to an energy of 3 trillion electronvolts would need to encircle the Earth and would cost about $170 billion.

    Thanks to the development of colliders and superconducting magnets, the 17-mile-long LHC has reached an energy level more than twice as high for a small fraction of Fermi’s estimated cost.

    Whatever the next step may be, physicists must look toward the future as an international community, panelists said.

    “The world has become more global, and we have contributed to that,” said Sergio Bertolucci, research director at CERN. “Things have changed.”

    According to scientists at the LHCP Conference, the discovery of the Higgs boson by a large international collaboration marked an era in which the big questions are tackled not by one nation, but by a global community.

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.

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