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  • richardmitnick 3:00 pm on November 22, 2014 Permalink | Reply
    Tags: , , , , Particle Accelerators, ,   

    From Triumf: “LHCb Experiment Confirms TRIUMF Prediction” 

    On Wednesday, November 19th, the LHCb collaboration at CERN’s Large Hadron Collider (LHC) announced the discovery of two new particles in the baryon family. The particles, known as the Xi_b’- and Xi_b*-, were predicted to exist by the quark model but had never been seen before.

    CERN LHCb New
    LHCb at CERN

    Randy Lewis, York University, and Richard Woloshyn (photographed), TRIUMF, submitted a paper together in 2009, “Bottom baryons from a dynamical lattice QCD simulation,” in which the masses of Xi_b’- and Xi_b* were predicted. This paper, among the eight theoretical papers cited in the LHCb collaboration report submitted to the Physical Review Letters, offered the LHCb researchers a light in the path of discovery.

    rw
    Richard Woloshyn

    “Theoretical and experimental physics complement each other in an important way,” said Petr Navratil, Head of Theory Department at TRIUMF. “Richard’s work illustrates how theoretical predictions motivate experimental efforts. Experimental results then provide feedback to improve the theoretical understanding.”

    The new particles are baryons made from three quarks bound together by the strong force. The types of quarks are different, though: the new Xib particles both contain one beauty (b), one strange (s), and one down (d) quark. Thanks to the heavyweight b quarks, the baryons are more than six times as massive as the proton. But the particles are more than just the sum of their parts: their mass also depends on how they are configured. Each of the quarks has an attribute called “spin“. In the Xi_b’- state, the spins of the two lighter quarks point in opposite directions, whereas in the Xi_b*- state they are aligned. This difference makes the Xi_b*- a little heavier.

    “Nature was kind and gave us two particles for the price of one,” said
    Matthew Charles of the CNRS’s LPNHE laboratory at Paris VI University.

    “The Xi_b’- is very close in mass to the sum of its decay products: if it had been just a little lighter, we wouldn’t have seen it at all using the decay signature that we were looking for.”

    “This is a very exciting result. Thanks to LHCb’s excellent hadron identification, which is unique among the LHC experiments, we were able to separate a very clean and strong signal from the background,” said Steven Blusk from Syracuse University in New York. “It demonstrates once again the sensitivity and how precise the LHCb detector is.”

    “I am happy that LHCb cites our work and that it appears on the broader stage, ” said Richard Woloshyn, “It shows the work we do here at TRIUMF and in Canada is important.”

    As well as the masses of these particles, the LHCb team studied their relative production rates, their widths – a measure of how unstable they are – and other details of their decays. The results match up with predictions based on the theory of Quantum Chromodynamics (QCD). QCD is part of the Standard Model of particle physics, the theory that describes the fundamental particles of matter, how they interact and the forces between them.

    sm
    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.

    “Our approach was based directly on QCD. These results give us confidence and show that the theory is adequate to deal with any measurement and to predict the outcomes of experiments,” said Richard.

    “This success is a reminder of TRIUMF’s leadership role in theoretical physics. Richard has been using the computational method called lattice QCD to make important contributions for many years, and I am one of several people who learned lattice QCD by spending time at TRIUMF with Richard,” said Randy Lewis.

    Richard admits that when he first saw the InterActions news release he did not expect it to be related to one of his theoretical ‘discoveries’ and set it aside to read later. It wasn’t until he saw the CBC headline, “New subatomic particles predicted by Canadians found at CERN” that he knew of his part in the discovery.

    See the full article here..

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    World Class Science at Triumf Lab, British Columbia, Canada
    Canada’s national laboratory for particle and nuclear physics
    Member Universities:
    University of Alberta, University of British Columbia, Carleton University, University of Guelph, University of Manitoba, Université de Montréal, Simon Fraser University,
    Queen’s University, University of Toronto, University of Victoria, York University. Not too shabby, eh?

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  • richardmitnick 12:27 pm on November 20, 2014 Permalink | Reply
    Tags: , , , , Particle Accelerators,   

    From CERN: “CERN makes public first data of LHC experiments” 

    CERN New Masthead

    20 Nov 2014
    Cian O’Luanaigh

    CERN today launched its Open Data Portal where data from real collision events, produced by experiments at the Large Hadron Collider (LHC) will for the first time be made openly available to all. It is expected that these data will be of high value for the research community, and also be used for education purposes.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    cern

    “Launching the CERN Open Data Portal is an important step for our Organization. Data from the LHC programme are among the most precious assets of the LHC experiments, that today we start sharing openly with the world. We hope these open data will support and inspire the global research community, including students and citizen scientists,” says CERN Director-General Rolf Heuer.

    The principle of openness is enshrined in CERN’s founding Convention, and all LHC publications have been published Open Access, free for all to read and re-use. Widening the scope, the LHC collaborations recently approved Open Data policies and will release collision data over the coming years.

    The first high-level and analysable collision data openly released come from the CMS experiment and were originally collected in 2010 during the first LHC run. This data set is now publicly available on the CERN Open Data Portal. Open source software to read and analyse the data is also available, together with the corresponding documentation. The CMS collaboration is committed to releasing its data three years after collection, after they have been thoroughly studied by the collaboration.

    CERN CMS New
    CMS

    “This is all new and we are curious to see how the data will be re-used,” says CMS data preservation coordinator Kati Lassila-Perini. “We’ve prepared tools and examples of different levels of complexity from simplified analysis to ready-to-use online applications. We hope these examples will stimulate the creativity of external users.”

    In parallel, the CERN Open Data Portal gives access to additional event data sets from the ALICE, ATLAS, CMS and LHCb collaborations, which have been specifically prepared for educational purposes, such as the international masterclasses in particle physics benefiting over ten thousand high-school students every year. These resources are accompanied by visualisation tools.

    CERN ALICE New
    ALICE

    CERN ATLAS New
    ATLAS

    CERN LHCb New
    LHCb

    “Our own data policy foresees data preservation and its sharing. We have seen that students are fascinated by being able to analyse LHC data in the past and so, we are very happy to take the first steps and make available some selected data for education” says Silvia Amerio, data preservation coordinator of the LHCb experiment.

    “The development of this Open Data Portal represents a first milestone in our mission to serve our users in preserving and sharing their research materials. It will ensure that the data and tools can be accessed and used, now and in the future,” says Tim Smith of the CERN IT Department.

    All data on OpenData.cern.ch are shared under a Creative Commons CC0 public domain dedication; data and software are assigned unique DOI identifiers to make them citable in scientific articles; and software is released under open source licenses. The CERN Open Data Portal is built on the open-source Invenio Digital Library software, which powers other CERN Open Science tools and initiatives.

    See the full article here.

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  • richardmitnick 9:42 am on November 19, 2014 Permalink | Reply
    Tags: , , , , Particle Accelerators,   

    From LHCb at CERN: “LHCb experiment observes two new baryon particles never seen before” 

    CERN New Masthead

    19 Nov 2014
    No Writer Credit

    graph

    Geneva 19 November 2014. Today the collaboration for the LHCb experiment at CERN’s Large Hadron Collider announced the discovery of two new particles in the baryon family. The particles, known as the Xi_b’- and Xi_b*-, were predicted to exist by the quark model but had never been seen before. A related particle, the Xi_b*0, was found by the CMS experiment at CERN in 2012. The LHCb collaboration submitted a paper reporting the finding to Physical Review Letters.

    CERN LHCb New
    LHCb at CERN

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    Like the well-known protons that the LHC accelerates, the new particles are baryons made from three quarks bound together by the strong force. The types of quarks are different, though: the new X_ib particles both contain one beauty (b), one strange (s), and one down (d) quark. Thanks to the heavyweight b quarks, they are more than six times as massive as the proton. But the particles are more than just the sum of their parts: their mass also depends on how they are configured. Each of the quarks has an attribute called “spin“. In the Xi_b’- state, the spins of the two lighter quarks point in opposite directions, whereas in the Xi_b*- state they are aligned. This difference makes the Xi_b*- a little heavier.

    “Nature was kind and gave us two particles for the price of one,” said Matthew Charles of the CNRS’s LPNHE laboratory at Paris VI University. “The Xi_b’- is very close in mass to the sum of its decay products: if it had been just a little lighter, we wouldn’t have seen it at all using the decay signature that we were looking for.”

    “This is a very exciting result. Thanks to LHCb’s excellent hadron identification, which is unique among the LHC experiments, we were able to separate a very clean and strong signal from the background,” said Steven Blusk from Syracuse University in New York. “It demonstrates once again the sensitivity and how precise the LHCb detector is.”

    As well as the masses of these particles, the research team studied their relative production rates, their widths – a measure of how unstable they are – and other details of their decays. The results match up with predictions based on the theory of Quantum Chromodynamics (QCD).

    QCD is part of the Standard Model of particle physics, the theory that describes the fundamental particles of matter, how they interact and the forces between them. Testing QCD at high precision is a key to refine our understanding of quark dynamics, models of which are tremendously difficult to calculate.

    sm
    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.

    “If we want to find new physics beyond the Standard Model, we need first to have a sharp picture,” said LHCb’s physics coordinator Patrick Koppenburg from Nikhef Institute in Amsterdam. “Such high precision studies will help us to differentiate between Standard Model effects and anything new or unexpected in the future.”

    The measurements were made with the data taken at the LHC during 2011-2012. The LHC is currently being prepared – after its first long shutdown – to operate at higher energies and with more intense beams. It is scheduled to restart by spring 2015.

    Further information

    Caption diagram : The mass difference spectrum: the LHCb result shows strong evidence of the existence of two new particles the Xi_b’- (first peak) and Xi_b*- (second peak), with the very high-level confidence of 10 sigma. The black points are the signal sample and the hatched red histogram is a control sample. The blue curve represents a model including the two new particles, fitted to the data. Delta_m is the difference between the mass of the Xi_b0 pi- pair and the sum of the individual masses of the Xi_b0 and pi-.. INSET: Detail of the Xi_b’- region plotted with a finer binning.

    Link to the paper on Arxiv: http://arxiv.org/abs/1411.4849
    More about the result on LHCb’s collaboration website: http://lhcb-public.web.cern.ch/lhcb-public/Welcome.html#StrBeaBa
    Observation of a new Xi_b*0 beauty particle, on CMS’ collaboration website: http://cms.web.cern.ch/news/observation-new-xib0-beauty-particle
    Footnote(s)

    1. CERN, the European Organization for Nuclear Research, is the world’s leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Israel, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Romania is a Candidate for Accession. Serbia is an Associate Member in the pre-stage to Membership. India, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer Status.

    See the full article here.
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  • richardmitnick 10:20 am on November 14, 2014 Permalink | Reply
    Tags: , , , , , Particle Accelerators,   

    From FNAL- “Frontier Science Result: CMS Origin of the smallest masses” 


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

    Friday, Nov. 14, 2014
    Jim Pivarski

    Since the discovery of the Higgs boson two years ago, about 80 analyses have helped to pin down its properties. Today, we know that it does not spin, that it is mirror-symmetric, and that it decays into pairs of W bosons, pairs of Z bosons, pairs of tau leptons, and pairs of photons (through a pair of short-lived top quarks). There are even weak hints at a fifth decay mode: decays into pairs of b quarks. All of these results are in agreement with expectations for a Standard Model Higgs boson, but they are still coarse measurements with significant uncertainties.

    sm
    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.

    To say that this boson is a Standard Model Higgs is to say that it is exactly the particle that was predicted in 1964. That leaves a lot of room for surprises. Without interference from new phenomena, the rate that this boson decays into particle-antiparticle pairs would be proportional to the square of the mass of the particle-antiparticle pairs. The best way to check the proportionality of something is to look at it on an extreme range. Since the Higgs is believed to give mass to everything from 0.0005-GeV electrons to 173-GeV top quarks, there’s plenty of room to check.

    dots
    Muons (red) are 18 times lighter than tau leptons (blue), so we expect Higgs decays to muon pairs to be about 300 times less common than Higgs decays to tau pairs.

    The highest decay rates are easiest to detect, so only the heaviest particle-antiparticle pairs have been tested so far. The lightest particle-antiparticle decay that has been observed is Higgs to pairs of tau leptons, which are 1.8 GeV each. The next-lighter final state that could be observed is Higgs to pairs of muons, which are 0.1 GeV each. By the expected scaling, Higgs to muon pairs should be 300 times less common. However, muons are easy to detect and clearly identify, so they make a good target.

    Even if you combine all the LHC data collected so far, it would not be enough to see evidence of this decay mode. However, the LHC is scheduled to restart next spring at almost twice its former energy. Higher energy and more intense beams would produce more Higgs bosons, making a future detection of Higgs to muon pairs possible.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    To prepare for such a discovery and find potential problems early, CMS scientists searched for Higgs to muon pairs in the current data set. They didn’t find any, but they did establish that no more than 0.16 percent of Higgs bosons decay into muons, only a factor of 7 from the expected number, and then they used these results to project sensitivity in future LHC data. Incidentally, the Higgs boson is the first particle known to decay into tau lepton pairs much more (6.3 percent) than muon pairs (0.023 percent). All other particles decay into taus and muons almost equally.

    CERN CMS New
    CMS in the LHC at CERN

    They also searched for Higgs decays into electrons, the lighter cousin of muons and tau leptons. Since electrons are 200 times lighter than muons, Higgs to electron pairs is expected only 0.00000051 percent of the time. None were found, though an observation would been an exciting surprise!

    See the full article here.

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  • richardmitnick 3:06 pm on November 13, 2014 Permalink | Reply
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    From FNAL- “Frontier Science Result: DZero Sharing the momentum” 


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

    Thursday, Nov. 13, 2014
    Leo Bellantoni

    The parts inside of a proton are called, in a not terribly imaginative terminology, partons. The partons that we tend to think of first and foremost are quarks — two up quarks and a down quark in each proton — but there are other kinds of partons as well.

    Each parton in a moving proton carries some momentum, which is a fraction of the total momentum of the proton. Because the partons interact with each other constantly, the momentum of a parton keeps changing. So at any particular time, there is some probability that the down quark is carrying, say, half the momentum of the proton, and later it might be a quarter of the total momentum. The fraction is called x. When the down quark is carrying half the momentum of the proton, it has an x of 0.5. These probabilities are key ingredients in calculating what happens in a hadron collider and can only be deduced from experiment.

    olot
    This plot shows the probabilities of finding up and down quarks with different fractions of a proton’s momentum. The vertical axis is arbitrary and different for the two curves. No image credit.

    The figure shows plots of the probabilities of finding up or down quarks at particular values of x. The vertical scale is a little arbitrary, but that won’t matter for us. Notice how the curve for down quarks, in blue, peaks at the left, at low values of x. That means that at any instant, the down quark tends to have a relatively small fraction of the proton’s momentum. The up quark curve, in red, has a ledge, a sort of bump in the generally downward slope at x around 0.2 or so. That means that the chances of an up quark having more momentum than a down quark are really pretty good.

    When a proton with a higher-momentum up quark hits an antiproton with a lower-momentum down antiquark, then these two partons can form a W+ boson, and that W+ boson is headed in the direction of the higher momentum. In a collision of an up antiquark and a down quark, a W- boson can be created that tends to travel in the antiproton direction. Things get a little more complicated when a W+ boson decays to a positron or a W- decays to electrons, but the positron and electron directions still carry information about the x-values of the colliding quarks.

    So the curves in the figure can be measured — or measured better — by looking at events in the Tevatron where a W+ or W- is produced and decays into a positron or electron and measuring the difference, or asymmetry, in the final electron and positron directions.

    DZero has measured the asymmetry in electron and positron directions relative to the direction of the proton’s motion when it collides with antiprotons in the Tevatron. The result is the most precise measurement of this asymmetry to date and provides important information about the momentum of the partons of protons. That information is critical in predicting what happens in all sorts of collisions involving protons, such as those at neutrino and LHC experiments.

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  • richardmitnick 3:09 pm on November 8, 2014 Permalink | Reply
    Tags: , , , Particle Accelerators, , , , The Conversation   

    From The Conversation: “Cheaper, more compact particle accelerators are a step closer” 

    The Conversation
    The Conversation

    Scientists working on an experiment at the SLAC National Accelerator Laboratory in the US have taken a step forward in developing a technology which could significantly reduce the size of particle accelerators. The technology is able to accelerate particles more rapidly than conventional accelerators at a much smaller size.

    two
    Before the big bang. SLAC National Accelerator Laboratory

    One of the most impressive aspects of particle accelerators used for research such as the Large Hadron Collider (LHC) at CERN is its physical size.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    Yet, even with a circumference of 27km, the LHC would be smaller than most of the next generation of proposed colliders. For example the International Linear Collider (ILC), a possible future collider of electrons and positrons (anti-electrons) could be 31km long, and there is even a proposal for a circular accelerator with an 80km circumference that could be built at CERN as part of the Future Circular Colliders (FCC) project.

    ILC schematic
    ILC schematic

    future
    fut2
    With the discovery of the Higgs boson at the LHC in 2012, coupled with the absence of other phenomena, the particle physics panorama has become, surprisingly perhaps, very open. While the Standard Model could appear as a complete theory, several undeniable observations tell us that there is more to the story. The nature of dark matter, the origin of the baryon asymmetry in the universe, the mysteries lying behind the very small neutrino masses are telling us to keep looking for answers. Are the required new phenomena to be found at higher energies, or have they escaped detection because of very small couplings? The FCCs will address these fundamental open issues of particle physics.

    The size of all of these machines is determined by our ability to build structures that can transfer energy to particles allowing us to accelerate them to greater speeds. The higher the speed, the greater the energy when these particle beams collide, giving scientists a better chance of answering fundamental questions about the universe. This is because higher energy collisions can create conditions that are similar to those existing when the universe was born.

    Most current accelerators use a structure called an “rf cavity”, a carefully designed “box” through which the particle beam passes. The cavity transfers electromagnetic energy into the kinetic energy of particles, accelerating them. However, there is a limit to the amount of energy that an rf cavity can transfer to particles. This is because, despite operating in a vacuum, there is a risk that increasing electromagnetic fields can lead to lightning-like discharges of energy.

    However, even routine experiments in places like the LHC require more energy than a single rf cavity can provide. That is why the current solution is to use very many cavities arranged in a straight line, if it is a linear machine such as the SLAC, or using the same cavity very many times if it is in a circular machine, such as the LHC.

    Either solution presents challenges and requires a large machine to fit in the many parts needed. This raises the costs. Any technology which can increase the acceleration with smaller parts and without the need for more machinery will make future accelerators more compact.

    This matters because particle accelerators are not just for particle physicists. They are increasingly used in medicine, industry and security. For example, accelerators provide X-rays and particle beams for cancer therapy, for the fabrication of minuscule devices and for scanning the contents of everything from suitcases to freight containers.

    The new technology which could promise more compact particle accelerators has just been published in a study in Nature. The study suggests that, if bunches of electrons are passed through a short column of lithium vapour “plasma” in rapid succession, the electric field of the plasma is able to translate enough energy to accelerate particles hundreds of times quicker than the LHC. It is able to achieve all this while only being 30cm in length.

    Plasma is a state of matter where atoms are broken down into positively charged ions and negatively charged electrons. Most of the matter in the sun exists as plasma, but we can create that state on Earth using high energy lasers.

    The electric field between particles in a plasma can be extremely high. In this experiment, as the bunch of electrons passes through the plasma it causes the electrons of the plasma to move, leaving behind it a region of oscillating electrons. It is this oscillation which generate the “wakefield” which can then be used to accelerate a second set of trailing electrons following very close behind the first bunch.

    Although previous experiments have shown even greater gains in energy, what makes this experiment interesting is the number of electrons accelerated and how evenly each of them acquires energy. Being able to accelerate large numbers of particles to the same energy simultaneously is a prerequisite for any future practical use of this technology called “plasma wakefield acceleration”.

    Other groups around the world including the AWAKE collaboration at CERN and the ALPHA-X collaboration based at the University of Strathclyde are pursuing different approaches to plasma wakefield acceleration using proton beams or lasers to generate the wakefield. Meanwhile there are already tentative designs being proposed for future accelerators that could make use of this technology, if accelerating large numbers of particles simultaneously can be made reliable.

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  • richardmitnick 1:24 pm on November 8, 2014 Permalink | Reply
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    From Daily Galaxy: “Discovery of “Higgs Boson” Points to an Undiscovered Force of Nature” 

    Daily Galaxy
    The Daily Galaxy

    November 08, 2014
    via University of Southern Denmark

    gal.

    Last year CERN [actually announced July 4.2012, editors] announced the finding of a new elementary particle, the Higgs particle. But maybe it wasn’t the Higgs particle, maybe it just looks like it. And maybe it is not alone. Many calculations indicate that the particle discovered last year in the CERN particle accelerator was indeed the famous Higgs particle. Physicists agree that the CERN experiments did find a new particle that had never been seen before, but according to an international research team, there is no conclusive evidence that the particle was indeed the Higgs particle.

    The research team has scrutinized the existing scientific data from CERN about the newfound particle and published their analysis in the journal Physical Review D. A member of this team is Mads Toudal Frandsen, associate professor at the Center for Cosmology and Particle Physics Phenomenology, Department of Physics, Chemistry and Pharmacy at the University of Southern Denmark.

    “The CERN data is generally taken as evidence that the particle is the Higgs particle. It is true that the Higgs particle can explain the data but there can be other explanations, we would also get this data from other particles”, Mads Toudal Frandsen explains.

    The researchers’ analysis does not debunk the possibility that CERN has discovered the Higgs particle. That is still possible – but it is equally possible that it is a different kind of particle. “The current data is not precise enough to determine exactly what the particle is. It could be a number of other known particles”, says Mads Toudal Frandsen.

    But if it wasn’t the Higgs particle, that was found in CERN’s particle accelerator, then what was it? “We believe that it may be a so-called techni-higgs particle. This particle is in some ways similar to the Higgs particle – hence half of the name”, says Mads Toudal Frandsen. Although the techni-higgs particle and Higgs particle can easily be confused in experiments, they are two very different particles belonging to two very different theories of how the universe was created.

    The Higgs particle is the missing piece in the theory called the Standard Model.
    sm
    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.

    This theory describes three of the four forces of nature. But it does not explain what dark matter is – the substance that makes up most of the universe. A techni-higgs particle, if it exists, is a completely different thing: “A techni-higgs particle is not an elementary particle. Instead, it consists of so-called techni-quarks, which we believe are elementary. Techni-quarks may bind together in various ways to form for instance techni-higgs particles, while other combinations may form dark matter. We therefore expect to find several different particles at the LHC, all built by techni-quarks”, says Mads Toudal Frandsen.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    If techni-quarks exist, there must be a force to bind them together so that they can form particles. None of the four known forces of nature (gravity, the electromagnetic force, the weak nuclear force and the strong nuclear force) are any good at binding techni-quarks together. There must therefore be a yet undiscovered force of nature. This force is called the the technicolor force.

    What was found last year in CERN’s accelerator could thus be either the Higgs particle of the Standard Model or a light techni-higgs particle, composed of two techni-quarks. Mads Toudal Frandsen believes that more data from CERN will probably be able to determine if it was a Higgs or a techni-higgs particle. If CERN gets an even more powerful accelerator, it will in principle be able to observe techni-quarks directly.

    The rest of the team behind the scientific paper is: Alexander Belyaev and Matthew S. Brown from the University of Southampton, UK and Roshan Foadi from the University of Helsinki, Finland.

    Ref: Technicolor Higgs boson in the light of LHC data. Phys. Rev. D 90, 035012th Alexander Belyaev, Matthew S. Brown, Roshan Foadi, and Mads T. Frandsen.

    Image at top of the page: The Black Eye galaxy is seen in this Hubble Space Telescope image released in 2004. Galaxies behave as if they contain much more mass than is visible to astronomers. NASA and the Hubble Heritage Team (AURA/STScI)

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  • richardmitnick 12:56 pm on November 8, 2014 Permalink | Reply
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    From Don Lincoln at Fermilab: “Higgs Boson: The Inside Scoop” 


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

    Aug 9, 2013

    FNAL Don Lincoln
    Don Lincoln

    [Don Lincoln is one of the world's best communicators of High Energy Physics.]

    In July of 2012, physicists found a particle that might be the long-sought Higgs boson. In the intervening months, scientists have worked hard to pin down the identity of this newly-found discovery. In this video, Fermilab’s Dr. Don Lincoln describes researcher’s current understanding of the particle that might be the Higgs. The evidence is quite strong but the final chapter of this story might well require the return of the Large Hadron Collider to full operations in 2015.

    Watch, enjoy, learn.

    See the full video 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 6:44 pm on November 4, 2014 Permalink | Reply
    Tags: , , , Particle Accelerators, ,   

    From BNL: “Physicists Narrow Search for Solution to Proton Spin Puzzle” 

    Brookhaven Lab

    November 4, 2014
    Karen McNulty Walsh

    New RHIC results reveal that gluons make a significant contribution to spin, an important intrinsic particle property; transient sea quarks also play a role.

    Results from experiments at the Relativistic Heavy Ion Collider (RHIC), a particle collider located at the U.S. Department of Energy’s Brookhaven National Laboratory, reveal new insights about how quarks and gluons, the subatomic building blocks of protons, contribute to the proton’s intrinsic angular momentum, a property more commonly known as “spin.” Specifically, the findings show for the first time that gluons make a significant contribution to proton spin, and that transient “sea quarks”—which form primarily when gluons split—also play a role.

    The new precision measurements will help solve a mystery that has puzzled physicists since the 1980s, when findings from early spin experiments in Europe and elsewhere simply didn’t add up. Those experiments showed that the spins of quarks—including the three valence quarks that determine most of the basic properties of the proton—plus antiquarks could account for, at most, a third of the proton’s total spin.

    thing
    How the spins of the building blocks of matter add up: Measurements from RHIC’s STAR and PHENIX experiments reveal that gluons (yellow corkscrews) contribute about as much as quarks (red, green, and blue) to the overall spin of a proton. But there is still a mystery to explain what accounts for the rest of the “missing” spin.

    “RHIC has conclusively, for the first time ever in the world, taken measurements to tell us that the gluon contribution to spin is about equal to the contribution of the quarks.”
    — RHIC physicist Renee Fatemi, University of Kentucky

    “Those results made it apparent that it was naïve to assume that the spin of the proton was carried by its three valence quarks, and this triggered a search for the source of the ‘missing’ spin,” said Brookhaven physicist Elke Aschenauer, a leader in the spin program at RHIC, a DOE Office of Science User Facility for nuclear physics research that was built in part to address this question. “RHIC is the only facility in the world capable of colliding spin-polarized protons,” Aschenauer said, explaining how colliding beams of protons with their spins aligned in a particular direction, and the ability to flip the polarization, gives physicists an elegant way to directly probe the spin contributions of gluons as well as quarks.

    Solving the proton spin puzzle is more than a matter of accounting. Tracking down the sources of proton spin is offering new insight into these particles’ internal structure—including quarks and the gluons that bind them, which are numerous and often split to form transient sea quarks. Spin can also have influence on a wide range of more familiar physical characteristics, including optical, electrical, and magnetic properties—some of which are used in everyday applications such as magnetic resonance imaging (MRI). Pinpointing where spin comes from could yield new information about the mechanisms of the complex subatomic particle interactions within protons, the effects of spin on other properties, and perhaps even ways to control those properties for future, unforeseen applications.

    Narrowing the focus

    mags
    Specialized accelerator magnets known as Siberian snakes have a corkscrew design that helps maintain the polarization of proton beams for RHIC experiments. Keeping all the proton spins aligned in a given direction within at least one of RHIC’s colliding beams helps scientists tease out the spin contributions of the proton’s internal components.

    The latest results on possible sources of spin, some published and some undergoing final analysis, come from the STAR and PHENIX collaborations, two groups each with 500+ scientists poring over data from millions of proton collisions at RHIC.

    BNL Star
    STAR

    BNL Phenix
    PHENIX

    BNL RHIC
    RHIC

    “After the early spin experiments found such a small contribution to spin from a proton’s quarks, people started making big predictions for gluons, the particles that hold quarks together within protons,” said Kieran Boyle, a fellow of the Riken-BNL Research Collaboration (RBRC) who conducts research at PHENIX.

    To gauge the gluon contribution, STAR measures jets of particles coming out of the proton-proton collisions when the spins of the protons in one beam align directly with the spins in the other beam, and repeating the experiment with the spins in one beam flipped, or antialigned relative to the other. PHENIX does the same thing, but measures the number of pions, the most abundant particles produced in jets. Any difference observed in jet or pion production rates when one proton beam’s polarization is flipped is an indication of how much the gluons’ spins are aligned with, and therefore contribute to, the spin of the proton.

    Early spin results from RHIC appeared to deepen the spin mystery, showing gluons didn’t make the huge contribution to spin that everyone had expected. In fact, the measurements came out close to zero, but with a lot of uncertainty.

    “The problem is that these measurements need a lot of data,” said Renee Fatemi, a University of Kentucky physicist who is a deputy spokesperson for the STAR experiment. “All we had was the ability to say the contribution [of gluons] wasn’t very huge. But with very little data we had very large error bars. All we could tell was the difference between huge and not huge.”

    More data reveal significant role of gluons

    RHIC has since collided many more polarized protons thanks to additional running time and accelerator advances that have vastly increased collision rates within each run and improved the degree of polarization in RHIC’s colliding proton beams. In addition, the detectors, particularly STAR, have new capabilities that allow them to capture more collision events. With these expanded data sets, the error bars have shrunk and both STAR and PHENIX now have definitive results.

    “RHIC has conclusively, for the first time ever in the world, taken measurements to tell us that the gluon contribution to spin is about equal to the contribution of the quarks,” about 20-30 percent of the total proton spin, Fatemi said.

    The fact that STAR and PHENIX got similar results gives the scientists great confidence in their findings.

    “These experiments were designed to be complementary,” said PHENIX deputy spokesperson John Lajoie of Iowa State University. “Measuring the same physics with different experiments gives us a way to cross-check our findings and also increases the validity of the comparisons of experimental results with predictions derived from nuclear physics theory.”

    There’s still a caveat to the claim, however, because RHIC is designed to measure particles streaming out of collisions in a particular “kinematic range”—tracking only the particles that emerge at particular angles. PHENIX mainly looks at particles streaming out perpendicular to the paths of the colliding protons. STAR captures that same range plus particles knocked a bit farther forward or backward from the collision zone—produced by more “lopsided” collisions between a high-momentum quark in one beam with a lower-momentum gluon in the other.

    “Our measurement makes assumptions about places we can’t even look yet,” Fatemi said. She emphasized that the new results build on the experiments that came before, thus showcasing the importance of extending the range of measurements. They also set the stage for possible future explorations, such as those that could be done at an electron ion collider (EIC), a facility nuclear physicists hope to build to help solve the spin mystery and other scientific challenges.

    “An EIC would allow us to make numerous, extremely precise measurements across a much wider range of momentum fractions,” Aschenauer said. “It would be the only facility in the world that could measure the distribution of polarized gluons as a function of their momentum and also their spatial distribution in the proton—like a microscope that resolves even the smallest features very precisely. ”

    Splitting fractions, gluons, sea quarks and spin

    But that doesn’t mean physicists have given up the quest to measure gluons’ role in spin even more precisely and over a greater range of momentum fractions at RHIC.

    For example, PHENIX is working on measuring the gluon contribution to the proton spin at more forward angles. These measurements will extend to a different kinematic region, giving results for the gluons carrying a smaller fraction of the overall momentum of the proton, which may offer further insight into the spin puzzle.

    The physicists are also searching for other possible sources of spin. In 2011, they reported the first measurements at RHIC of so-called sea quarks, virtual quark-antiquark pairs that form when gluons achieving a certain energy—say, when protons are accelerated to near the speed of light at RHIC—split and then reform. Though these transient sea quarks flit in and out of existence, they may contribute to spin—and possibly in a way that depends on their flavor.

    col
    Collisions of polarized protons (beam entering from left) and unpolarized protons (right) result in the production of W bosons (in this case, W-). RHIC’s detectors identify the particles emitted as the W bosons decay (in this case, electrons, e-) and the angles at which they emerge. The colored arrows represent different possible directions, which probe how different quark flavors (e.g., “anti-up,” u and “down,” d) contribute to the proton spin.

    To track the sea quarks’ contributions to spin, physicists again compare what happens when the polarization of one of RHIC’s beams is flipped, but this time colliding it with an unpolarized proton beam and tracking the production of particles called W bosons.

    “W’s are produced when a quark inside a proton in one beam collides with an antiquark in the other beam. So W’s are more selective than jets, which can come from quark-quark, gluon-gluon, or quark-gluon interactions,” said Ernst Sichtermann, a physicist at DOE’s Lawrence Berkeley National Laboratory and another deputy spokesperson for STAR. “The Ws pick out the quark-antiquark signal.”

    Even better, the electric charge of the W can precisely identify the type, or flavor, of the antiquark involved in the collision. W- particles decay into electrons, giving information about “anti-up” quarks, while W+ particles decay into positrons, revealing information about “anti-down” quarks.

    So far the results from PHENIX and STAR indicate these sea quarks make a fairly minor contribution to spin. More specifically, the measurements of W+ particles at RHIC indicate that the anti-down quarks’ contribution to spin is in agreement with earlier experiments that looked at sea quark contributions in a less direct way.

    “Our result is more precise and was done in a different way, which provides strong confirmation of what’s been seen before,” STAR’s Fatemi said.

    The results for W-, on the other hand, give the first glimpse that there is an unexpected difference in the polarizations of the anti-up and anti-down sea quarks.

    “While our uncertainties are still significant, the RHIC data hint that the contribution from W-, or anti-up quarks, may be a bit larger than had been expected,” Sichtermann said.

    Aside from suggesting a difference in the spin contribution depending on the flavor of the antiquark, this result could offer interesting insight into the mechanism by which gluons split to form sea quarks in the first place, Sichtermann said.

    “Gluons can split into up/anti-down or down/anti-up,” he explained. “If that’s the only mechanism, and gluons don’t care about flavor, you should get equal numbers and equal polarization. So if there is a preference [for anti-up quarks to be more polarized than anti-down], there must be some other mechanism for generating these sea quarks.”

    STAR will continue to analyze data to increase precision. “With the 2013 data, we have every expectation that the uncertainties could be reduced and we may have evidence in the end,” Sichtermann said.

    Again, the measurement from STAR comes from the most central region of the collision, not a wide range of momentum fractions. “More forward measurements using similar methods to measure muons will be able to better tease out the antiquark contributions,” PHENIX’s Boyle said. Recent upgrades to enhance the detection of forward muons were in place for the 2013 run, the data has been fully reconstructed, and the PHENIX collaboration is currently finalizing the results for publication.

    “Together, these results show that RHIC lays the ground work for starting to understand the complexity of the spin of the proton—one of the fundamental quantum numbers of every single particle in the universe,” Aschenauer said. “But the ultimate answer to unravel its mystery would come from an EIC.”

    Research at RHIC is funded primarily by the DOE Office of Science (NP), and also by these agencies and organizations.

    See the full article here.

    BNL Campus

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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  • richardmitnick 1:40 pm on November 4, 2014 Permalink | Reply
    Tags: , , , , Particle Accelerators,   

    From Symmetry: “Fabiola Gianotti chosen as next head of CERN” This is great news!! 

    Symmetry

    November 04, 2014
    Kathryn Jepsen

    The former head of the ATLAS experiment at the LHC will be the first female leader of Europe’s largest particle physics laboratory.

    Today the CERN Council announced the selection of Italian physicist Fabiola Gianotti as the organization’s next director-general.

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    Gianotti was leader of the ATLAS experiment at the Large Hadron Collider from March 2009 to February 2013, covering the period in which the ATLAS and CMS experiments announced the long-awaited discovery of the Higgs boson, recognised by the award of the Nobel Prize to François Englert and Peter Higgs in 2013. She will be the first woman to hold the position of CERN director-general.

    “We were extremely impressed with all three candidates put forward by the search committee,” says CERN Council President Agnieszka Zalewska. “It was Dr Gianotti’s vision for CERN’s future as a world-leading accelerator laboratory, coupled with her in-depth knowledge of both CERN and the field of experimental particle physics that led us to this outcome.”

    The appointment will be formalised at the December session of Council. Gianotti’s mandate will begin on January 1, 2016, and will run for a period of five years.

    “It is a great honor and responsibility for me to be selected as the next CERN director-general following 15 outstanding predecessors,” Gianotti says. “CERN is a center of scientific excellence and a source of pride and inspiration for physicists from all over the world. CERN is also a cradle for technology and innovation, a fount of knowledge and education and a shining, concrete example of worldwide scientific cooperation and peace.

    “It is the combination of these four assets that renders CERN so unique, a place that makes better scientists and better people. I will fully engage myself to maintain CERN’s excellence in all its attributes, with the help of everybody, including CERN Council, staff and users from all over the world.”

    Gianotti received her PhD in experimental particle physics from the University of Milan in 1989. Since 1994 she has been a research physicist in the Physics Department of CERN. She has worked on several CERN experiments, being involved in detector R&D and construction, software development and data analysis. She is the author or co-author on more than 500 publications in peer-reviewed scientific journals.

    Since August 2013 she has been an honorary professor at the University of Edinburgh. She received honorary doctoral degrees from the University of Uppsala, the Ecole Polytechnique Federale de Lausanne, McGill University and Oslo University.

    She was included among the “Top 100 most inspirational women” by The Guardian newspaper in the UK in 2011, chosen as a runner-up for Time magazine’s 2012 “Person of the Year,” included among the “Top 100 most powerful women” by Forbes magazine in 2013 and considered among the “Leading global thinkers of 2013” by Foreign Policy magazine.

    She is a member of the Italian Academy of Sciences and has served on several other international committees. She was recently selected to be a member of the Scientific Advisory Board of the UN Secretary-General, Ban Ki-moon.

    “Fabiola Gianotti is an excellent choice to be my successor,” says current CERN Director General Rolf Heuer. “It has been a pleasure to work with her for many years. I look forward to continuing to work with her through the transition year of 2015 and am confident that CERN will be in very good hands.”

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.


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