Wednesday, July 04, 2012

Elementary Physics - Higgs Boson Experiments

Later UPDATES included ! .................... 中文的网站

Announcement on German TV (above).

At the Large Hadron Collider (LHC) site in Geneva, the existence of a new elementary particle, resembling the predicted Higgs boson, has been confirmed. The news have been unveiled today in a conference on latest results of elementary particle research in Geneva. Peter Higgs who once predicted the existence of a similar boson and gave it his name received international congratulations, even though it is not quite clear if the new particle found in experiments is really identical with the Higgs boson. As to the theory of that mysterious Higgs particle, here is what CERN Institute in Geneva, who are operating the LHC facility there, recently published:

" A major breakthrough in particle physics came in the 1970s when physicists realized that there are very close ties between two of the four fundamental forces – namely, the weak force and the electromagnetic force. The two forces can be described within the same theory, which forms the basis of the Standard Model. This ‘unification’ implies that electricity, magnetism, light and some types of radioactivity are all manifestations of a single underlying force called, unsurprisingly, the electroweak force. But in order for this unification to work mathematically, it requires that the force-carrying particles have no mass. We know from experiments that this is not true, so physicists Peter Higgs, Robert Brout and François Englert came up with a solution to solve this conundrum.

They suggested that all particles had no mass just after the Big Bang. As the Universe cooled and the temperature fell below a critical value, an invisible force field called the ‘Higgs field’ was formed together with the associated ‘Higgs boson’. The field prevails throughout the cosmos: any particles that interact with it are given a mass via the Higgs boson. The more they interact, the heavier they become, whereas particles that never interact are left with no mass at all.

This idea provided a satisfactory solution and fitted well with established theories and phenomena. The problem is that no one has ever observed the Higgs boson in an experiment to confirm the theory. Finding this particle would give an insight into why particles have certain mass, and help to develop subsequent physics. The technical problem is that we do not know the mass of the Higgs boson itself, which makes it more difficult to identify. Physicists have to look for it by systematically searching a range of mass within which it is predicted to exist. The yet unexplored range is accessible using the Large Hadron Collider, which will determine the existence of the Higgs boson. If it turns out that we cannot find it, this will leave the field wide open for physicists to develop a completely new theory to explain the origin of particle mass. "

On the contrary, if the Higgs particle is found as it seems to be by now, this will imply the confirmation of an already found theory and light the way to further experiments and discoveries on the functioning of our universe.

By the way, I heard about today's press conference in Geneva some days before when I visited Max-Planck-Institute of Physics (Werner-Heisenberg-Institut) in Munich. On a visitor's day dedicated to quantum mechanics and astrophysics they already gave some cryptic hints about new discoveries to be awaited in the immediate future. It was then for me to wait only some days for the announcement.

The German Werner-Heisenberg-Institute is engaged in scientific research done for the Large Hadron Collider in Geneva as one of the main detectors for this project, named the ATLAS detector, has been constructed with the aid of German physicists. ATLAS is an enormous and most sophisticated detector consisting of four main elements:

- An inner detector that measures the momentum of charged particles.
- A calorimeter unit for the measurement of energies carried by particles.
- A Muon spectrometer that identifies and measures the momenta of Muons.
- A magnet system bends charged particles for momentum measurement. The solenoid magnet surrounds the inner detector. Arrows point to toroid magnets.

The ATLAS detector can be used not only to detect the Higgs boson but as well to enlighten the relation between matter and antimatter and to find possible constituents of dark matter.

ATLAS detector under construction (above).

Large Hadron Collider LHC (above):
Accelerating circle for charged elementary particles and detector positions.

Because of the Higgs boson being a very massive particle and which decays almost immediately when created, only a very high energy particle accelerator can observe and record it. That's why the LHC is being used. Its special feature is the ability to collide protons being accelerated to a speed not too far away from the speed of light. Under such circumstances, a "zoo" of elementary particles can be created and rarely observed events might be detected. It was the idea that, with some luck, even the predicted Higgs particle could be observed. As to that, latest measuring results are giving rise to great hopes.

According to detailed information, measuring data have been compared from two separate main detectors of the LHC facility: The ATLAS detector and the CMS device which is an electromagnetic crystal calorimeter (=> refer to the above illustration). Both experiments are proving the existence of a very massive particle regarded as the Higgs boson or something very near to it.

Above: A typical candidate event for the possible formation of Higgs bosons including two high-energy photons whose energy (depicted by red towers) is measured in the CMS electromagnetic calorimeter. The yellow lines are the measured tracks of other particles produced in the collision of protons. The pale blue volume shows the CMS crystal calorimeter barrel.

Above pictures: One mechanism of formation for the Higgs particle in the Large Hadron Collider. A gluon-gluon fusion, triggered off by a proton-proton collision, is leading to a so-called top quark loop where pairs of top and anti-top quarks are being generated. From there the formation of a Higgs boson. The upper picture is showing a possible way how the Higgs particle can decay by emitting two high energy photons that can be measured in the CMS calorimeter. ( A short description of above mentioned elementary particles is given further down. )

Here is what Scientific American wrote after the announcements from CERN:

" Unlike some past announcements centered on the Higgs in the past few years, which have produced as much ambiguity and confusion as anything else, this one did not disappoint. ATLAS physicists said that their most recent data reveal the presence of an unknown particle with a mass of about 126.5 GeV, or 126.5 billion electron-volts. An electron-volt is a physicist’s unit of mass or energy; for comparison, the proton has a mass of about 1 GeV. The CMS collaboration found evidence for a new particle with a mass of 125.3 GeV.
[The traditional characterization of a particle's mass "m" in terms of energy "E" is referring to Einstein's equation E = m c² where "c" is the speed of light. As to the Higgs particle detected, its average mass is corresponding to that of 132 protons.]
Crucially, both teams' findings appear exceptionally robust. In physics terms, evidence for a new particle requires a “3-sigma” measurement, corresponding to a 1-in-740 chance that a random fluke could explain the observations, and a claim of discovery requires a 5-sigma effect, or a 1-in–3.5 million shot that the observations are due to chance. In December representatives of the two experiments had announced what one called “intriguing, tantalizing hints” of something brewing in the collider data. But those hints fell short of the 3-sigma level. The new ATLAS finding met not just that level of significance but cleared the gold standard 5-sigma threshold, and CMS very nearly did as well, with a 4.9-sigma finding. "

Above: One possible signature of a Higgs boson from a simulated proton–proton collision. It decays almost immediately into two jets of hadrons and two electrons, visible as lines. Hadrons are massive particles bearing the mass of, at least, two or more protons (or neutrons).

Above: Formation and decay of a Higgs boson. This time it's a decay into hadrons and leptons. If leptons are being represented by electrons, we have a situation like that predicted for the simulated process further above where two jets of hadrons and two electrons are being produced.

Above: Another mechanism of formation for the Higgs particle in the Large Hadron Collider. From there it could be imagined that different patterns of decay might exist as well as can be studied in the simulation further above.

Above: Summary of interactions between particles described by the Standard Model. Leptons are particles with negligible mass like electrons. Quarks are considered to be the basic constituents of all elementary particles while gluons are either keeping protons and neutrons together in the nucleus of an atom or "glue" together those quarks that constitute more complicated structures like protons. The W and Z particles are massive bosons like the predicted Higgs boson itself while photons are massless "parcels of energy".



According to a mainstream theory in particle physics, the Higgs boson is essential for the transference of mass to any other particle known in the formation of "real" matter as we know it from daily experience in the world we live in. The transference of mass by means of a Higgs field and which is, in most theories, represented by a Higgs particle could then be imagined using the following model of thought, the Cocktail Party Simile:

A group of people is gathering on a cocktail party, no one knowing each other. At first, those persons are rather regularly distributed until a well-known celebrity appears that attracts the interest of everybody. People are now approaching that celebrity who finds it more and more difficult to move because of a growing cluster of persons in his/her reach. A similar effect would have been reached if the celebrity's inert mass was growing without other people surrounding him or her. An increase or transference of mass would therefore take place whenever a certain particle or person with a special ability to attract or transfer mass appears in a defined environment of other particles or persons. Same thing would happen if only a "massless rumour" enters into a cocktail party environment. People would cluster in order to hear what it's all about and thereby create a ball of mass. Such could be the mechanism predicted for the interaction of elementary particles with the Higgs boson.

While speaking about the importance of Higgs particles in the formation of "real" matter that everybody is attached to in daily life, it needs to be mentioned that only 5% of all matter present in the universe really belong to that kind of matter. Further 20% of all matter are being represented by so-called dark matter we don't know much about. Moreover, the remaining 75% of all matter in the universe can be considered as the mass equivalent of a so-called dark energy which makes up for another field of future research.


As mass media are usually inclined to overestimate the importance of a single discovery on the way to greater understanding of our universe, the word of a "God Particle" has been associated with the Higgs boson. It should be made clear that "God" doesn't appear in the vocabulary of modern physics. Peter Higgs is an atheist, and is displeased that the Higgs particle is nicknamed the "God particle", because that term "might offend people who are religious" [Higgs in an interview with New Scientists, 2008].

Above: Headline of People's Network, Beijing, on July 7, the first day they reacted on a recent announcement from CERN. The headline is reading:

The "God Particle" originally is a "Goddamned Particle"
which is a quotation from Peter Higgins referring to the long time it took to approach the particle's existence.

In different articles, the Chinese network is praising the new particle detection as a "big step for mankind" and marking its importance:

The discovery of that new particle confirms
the capacity of mathematical prediction.

On July 10, 2012, China Daily, Beijing, published an article titled "Chinese link in missing-link breakthrough". In that article they are telling us that Chinese physicists have been contributing to one of the most ambitious scientific experiments ever attempted - a search for the missing link [i.e. the Higgs boson] at the beginning of the universe. There are quotations from Chen Guoming, one of 30 Chinese scientists who represented the Institute of High Energy Physics at the Chinese Academy of Sciences during the experiments at the Large Hadron Collider facility in Geneva. Chen was one of 3,000 scientists from 175 universities or research institutions in 38 countries and regions who have spent several years at the Large Hadron Collider site of CERN.

The above article on Higgs boson experiments has
been compiled by Dr. rer.nat. Wolfgang Wiesner.

Internet access points for Washington D.C. and outskirts, activated between 29 June and 14 July, 2012, by visitors to "blueprint news":

"Postcard" from the White House:

"Massive elementary particles colliding over the issue [i.e. Syria]".


Internet access points for New York / New Jersey, activated between 19 June and 4 July, 2012, by visitors to "blueprint news":

Localized visitor access point in Manhattan / New York, activated by a visitor who looked for another blogspot of mine on astronomy:

Postscript on September 6, 2013:

For more than one year, the above blogspot on elementary physics has been visited by lots of professionals who came from different parts of the world. This blogspot even became one of the most popular items of my news blog. Among many remarkable visitors or institutions the following example should serve as a proof for that.

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