giovedì 13 ottobre 2011


The standard model contains all the secure knowledge in particle physics. It describes the building blocks of matter and the rules that they obey. All matter is composed of quarks and leptons (the electron also belongs to these). The four elementary forces acting between the particles is transmitted from the mediating particles (which are the graviton for gravity, the photon to the electromagnetic force, W and Z bosons for the weak force, the gluon for the strong force). All these particles are 'point', hence the term just means that, even in experiments with the highest resolution, it is not possible to measure effects related to their extension.

The intensity of each of the four fundamental forces is determined by properties of the particles that can be described as generalized charges. In the case of electromagnetism this property is the well-known electrical charge, while in the case of gravitation is the mass. The forces, weak and strong are not part of our daily experience: the concepts of "weak charge" and "color charge" introduced by physicists for these properties are therefore a bit abstract.
These different positions are measured in different units: for example the mass in grams and the electric charge in coulombs. In order to compare the forces, particle physicists use, however, in lieu of charges, dimensionless coupling constants. The larger this constant, the more intense the radiation of the carrier particle, and thus the greater the force.
Is the particle mass mediators to determine essentially how the force depends on the distance (see Yukawa theory): if the mass is zero, as in the case of the photon and the graviton (remember to be the mediating particles, respectively, the electromagnetic force and gravitation), the radius of action of the force is infinite, so we know these forces also by our macroscopic world in everyday life. The so-called W and Z bosons, mediators of the weak force,have a mass one hundred times greater than that of the proton, so the range of the weak force is limited to one hundredth of the diameter of the proton, ie 2x10 ^ -18 meters.
The situation is completely different in the case of the strong force. Though its mediating particles - gluons - are massless, its range is equal only to the radius of the proton (about 10 ^ -15 meters). The value of strong coupling constants is therefore so small that only for distances much less than the radius of the proton, we can use the image of individual particles and solve the equations of quantum chromodynamics (QCD) in the same way already used in QED. For longer distances, the coupling constant, as a result of the interactions with the gluons, carrying the color charge, becomes so great that it is impossible, for example, separate from the others, one of the three quarks that make up the proton. You fail to include the methods of calculation of QCD, and so far have not been able to find satisfactory answers to theoretical questions about the structure of the proton or the confinement of quarks and gluons in the proton. In order to go further we must rely primarily on experimental research, such as those that are conducted in the Hera collider.

The strong nuclear force still offers several puzzles: how quarks and gluons together to form the proton? As the strong force varies as a function of distance between pairs of particles? Why quarks and gluons are always enclosed in particles such as protons and neutrons and can never be observed as free particles? The four fundamental forces can have a common origin, as suspected, most physicists, and be described by a single theory?The experiments conducted with particle accelerators, such as those performed in the collider Hera, in Hamburg, have made an essential contribution to find answers to these questions.Hera (which stands for Hadron-Elektron-Ring-Anlage, namely 'loop system for hadrons and electrons ") is the most important particle accelerator laboratory DESY (Deutsches Elektronen-Synchroton). The plant consists of two rings of accelerating 6336 meters in circumference each, built at a depth of about 30 meters in a tunnel under the city districts of Bahrenfeld and Lurup. A ring accelerates electrons (but also wanting their antiparticles, positrons), leading up to an energy of 27.5GeV, while the other accelerates protons to an energy of 920GeV.In the vacuum of the two storage rings, electrons and protons zipping in opposite directions for hours. They travel at nearly the speed of light along their route about 47,000 times a second and collide head-on in two experimental spaces. Take place here the experiments called H1 and Zeus : detectors with size of houses, weighing several thousand tons, record the collisions between the particles and traces of secondary particles that are generated in collisions. Of the many thousands of such events occurring every second, the most interesting ones are recorded for later interpretation.The standard model contains all the safe knowledge in particle physics. It describes the building blocks of matter and the rules that they obey. All matter is composed of quarks and leptons (the electron belongs to these). The four elemental forces operating between the particles are transmitted from the mediating particles (which are the graviton for gravity and the photon to the electromagnetic force, W and Z bosons for the weak force, the gluon for the strong force). All these particles are "point", hence the term simply means that, even in experiments with the highest resolution, it is not possible to measure effects related to their extension.The experiments conducted with the H1 and Zeus, Hera were able to measure more precisely the intensity of this force that operates between the quark. From the measurements made with Hera was known that the quarks in the proton emit gluons, and that they generate further gluons or quark-antiquark pairs. Most physicists, however, was convinced that, in addition to the three valence quarks in the proton, they were only a few pairs quark - antiquark and only few gluons and therefore that the proton was almost empty. According to new measurements, however, the interior of a proton resembles in a seething thick broth in which gluons and quark-antiquark pairs are continuously generated and annihilated again. This high density of the emission of gluons is a completely new state, so far not investigated, of the strong force. In our opinion, is due precisely to this state if quarks and gluons are "confined" inside the proton, and are therefore never observed as free particles.Hera has provided another surprise: the prospective trial was that, in the violent collisions that occur in high power accelerators, protons were crushed in a large number of new particles. Instead in 15 percent of the proton collisions they remained intact, even though he had undergone a vigorous interaction. But as a proton can survive the collision, when a quark is violently gotten out from it ? The thing seems utterly incomprehensible. It clearly depends on a flagship property of the strong force, which should help us understand why quarks and gluons are confined in the proton.The discovery of these events led to an intense collaboration between theoretical and experimental physicists. Both collider experiments to the Hera - H1 and Zeus - were changed to extend the measurements to lower values ​​of pulse to better investigate the protons diffuse. The first theoretical attempt, with the help of models, to explain the high density of the emission of gluons in the scattering process. This research has made great strides in the meantime. And maybe you will soon figure out how the strong emission of gluons can prevent that quarks and gluons emerge as free particles from diffusion process, and as protons can remain intact.Summarize once again: the collider experiments performed with Hera, using electrons as probes, have been brought under the lens of this supermicroscope the structure of the proton and the fundamental forces of nature, allowing to observe with a resolution never achieved before. In this context, for the first time become accessible to measurement, the weak force and electromagnetic force behave exactly as predicted by the standard model of particle physics ; though at great distances their intensities are quite different, they have however a common origin. The difference depends on the diversity of particle mass mediators.The theory of the strong force (quantum chromodynamics) was confirmed in the most accurate for small distances. The structure of the proton is detected very complex because, in the case of small pulses, the density of quarks and gluons is very high. Moreover, against all expectations, protons often emerge intact from the diffusion process. The two new observations re-propose in a completely new way the fundamental question:

"Why quarks and gluons are imprisoned inside the proton?".

The Author:ROBERT KLANNER is a professor of experimental physics at the University of Hamburg in December 1999 and is director of research of Deutsches Elektronen-Synchrotron (DESY) in the same city. At the center of his interests are the development of particle detectors and the investigation of the strong interaction and the structure of hadrons. Before moving to Hamburg in 1984, had already worked with several large accelerators: a Serpuchov (Russia), at Fermilab, near Chicago, and the European Laboratory for Particle Physics (CERN) in Geneva.

Maianni Luciano, La fisica delle particelle, «Le Scienze quaderni» nr. 103, settembre 1998
Rith Klaus e Schäfer Andreas, Il mistero dello spin dei nucleoni, in «Le Scienze» nr. 173, settembre 1999

OPHERA because the title to this post? Because according to the MT the incredible results of the “Opera” experiment conducted by equipe of Professor Antonio Ereditato between CERN and the Gran Sasso underground laboratories are closely related to those obtained in HERA such as in the previous article that ends with the question:”Why do quarks and gluons inside the proton are imprisoned? ".A structure such as a proton, composed of localized particles (quarks) that exchange mass bosons (gluons) can not be stable, because it does not respect the law of conservation of momentum that even at quantum scale is valid and active (see Moessbauer effect). Now three quarks exchanging gluons should not only recoil, but also absorb the momentum of the gluons received and the proton would explode unless an external pressing force, exerted by a physical "material" space, confines quarks. But this kind of action is conceivable, beyond the standard model which provides estimates of point particles, only by adopting a model in which the particles are unlocalized matter waves, such as Louis De Broglie hypothesized."Almost particles" as solitons or dromions (Attilio Maccari: that make up perturbations of the same fields whose they belong constituting also the surrounding space. The change in frequency of the waves determines the modulation of the thrust and counter thrust being able to maintain the balance between internal and external. So, for example, when a quark is "ripped" to a proton, internal matter quickly “repairs” itself and restore balance. So neutrinos, rather than exceed the speed of light, could have simply underpass geodesics impressed by gravity to the space-time digging a tunnel through such that kind of space ; in other words, light geodesic wouldn’t minimum distance lines between points. In place of the space - time there would be a normal three-dimensional euclidean space that can be traversed in a tendential straight line which is not to bend space - time, but electromagnetic radiation. On the other hand, excluding statistical and systematic errors, or neutrinos were faster than light (with all the theoretical consequences of the case) or have taken a "shortcut". This would make safe goats (experiment) and cabbage (insuperability of c).But this "short cut", like a tunnel, needs "something real" to be "dug".The Alice experiment conducted at the Large Hadron Collider (LHC) could detect a continuous spectrum of emission/absorption of collisions between protons as a "calling card" of these waves of matter formed by the "almost particles".Taking, then, that until now, the Atlas experiment, also conducted at the LHC, has ruled out the existence of the Higgs boson in a wide range of mass/energy, it can be assumed that, even for the same name field, on the detectors may have a distribution of statistical data more and more 'homogeneous with reduction of the"peaks" with increasing energy, to indicate the presence of mass/energy unlocalized, in place of localized massive vector bosons.

Stefano Gusman

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