Higgs boson seminar: have physicists found the 'god particle'? – live | Science. 12.50pm: Cern, the European particle physics lab near Geneva, has called a special seminar at 1pm GMT at which scientists working on the two main detectors on the Large Hadron Collider (LHC) will share their results. They will hold a press conference at 3.30pm when they are expected to announce they have good evidence for the existence of the Higgs boson. Follow events here as they unfold during the afternoon, including the announcement, the key data and reaction from around the world. 12.56pm: In case you've been distracted by other news over the past few months, here's a quick catch-up.
The Higgs boson is a subatomic particle that was predicted to exist nearly 50 years ago. Scientists have been searching for the particle for decades, but so far have no solid proof that it is real. Scientists have no hope of seeing the field itself, so they search instead for its signature particle, the Higgs boson, which is essentially a ripple in the Higgs field. But the Higgs field is selective. Why We Need the Higgs, or Something Like It | Cosmic Variance. In the comments to the previous post, Monty asks a perfectly good question, which can be shortened to: “Is the Higgs boson really necessary?” The answer is a qualified “yes” — we need the Higgs boson, or something like it.
That is, we can’t simply take the Standard Model as we know it and extend it to arbitrarily high energies without new physics kicking in. The role of the Higgs field is to break the symmetry of the electroweak interactions, as discussed here. We think that there is a lot of symmetry underlying particle interactions, but that much of it is hidden from our low-energy view. In technical terms, the electroweak theory of Glashow, Weinberg and Salam posits an “SU(2)xU(1)” symmetry, that somehow gets broken down to “U(1).” That unbroken symmetry gives us electromagnetism, a force carried by a massless particle, the photon.
The broken symmetries are still there, but their force-carrying particles become massive when the symmetry breaks — those are the W+, W-, and Z0 bosons. Rolling the dice: understanding how physicists hunt for the Higgs. Tomorrow, CERN will be webcasting a talk on the latest results in its search for the Higgs boson, a particle that is theorized to provide other particles with mass. The director of CERN has gone on record as saying there won't be any announcement that we've definitively discovered the Higgs, nor will there be any statement indicating that we've completely ruled out its existence. Still, expectations are high that we'll find some signal indicating the Higgs is probably at a specific mass—rumors have it near either 120 or 140GeV. Even as the webcast proceeds, science writers everywhere will be scrambling to explain the results.
We thought we'd get a jump on things and give you an explanation of what exactly the scientists at the LHC's two general-purpose detectors, ATLAS and CMS, are looking for, and why it's so hard to be certain about what they've seen. Theoretical models of the Higgs indicate it has several ways of decaying; one example is by producing two high-energy photons. L’existence du boson de Higgs sera-t-elle confirmée en 2012 ? Grâce à l’énorme quantité de données accumulées par le LHC, les scientifiques ont d’ores et déjà réussi à circonscrire l’espace dans lequel se cache le boson de Higgs. Le boson de Higgs est la pièce maîtresse du "Modèle standard de la physique des particules", qui a été inventé dans les années soixante.
Le rêve de la communauté scientifique : que ces expériences permettent de confirmer ou d’infirmer l’existence du fameux boson, encore jamais détecté à ce jour. Genève, le 31 octobre 2011. Après six mois d’exploitation et quatre cent trillions de collisions proton-proton, l’exploitation avec protons du LHC a pris fin le 31 octobre 2011. Au début de la campagne d’exploitation de cette année, le LHC avait pour objectif de livrer aux expériences courant 2011 un femtobarn inverse (1 fb-1) de données, dans le langage des physiciens.
"Nous avons effectué un nombre considérable de mesures du Modèle standard et franchi des territoires jusqu’ici inexplorés à la recherche d’une nouvelle physique. Communiqué de Presse. Higgs boson: Excitement builds over 'glimpses' at LHC. 13 December 2011Last updated at 04:19 ET By Paul Rincon Science editor, BBC News Website, Geneva The Higgs, so far, exists definitively only in simulations Anticipation is building in the run-up to presentations of the best-yet evidence for - or against - the existence of the Higgs boson. The famed particle is a missing link in current theories of physics, used to explain how things gains their mass. Rumours have been swirling about the findings for weeks, ahead of the announcement on Tuesday afternoon.
It is likely to yield only tantalising hints, as the teams do not have enough data to claim a formal discovery. However, most physicists concede that not finding the Higgs boson is as exciting a prospect as finding it in the place where existing theory predicts it should be. "If we wouldn't find it it would be even - in a way - more exciting, but you know, both ways, it's a win-win situation," said Prof Stefan Soldner-Rembold, a particle physicist from the University of Manchester.
Field day. Planck units. Originally proposed in 1899 by German physicist Max Planck, these units are also known as natural units because the origin of their definition comes only from properties of the fundamental physical theories and not from interchangeable experimental parameters. Planck units are only one system of natural units among other systems, but are considered unique in that these units are not based on properties of any prototype object or particle (that would be arbitrarily chosen), but rather on properties of free space alone. The universal constants that Planck units, by definition, normalize to 1 are: the gravitational constant, G,the reduced Planck constant, ħ,the speed of light in a vacuum, c,the Coulomb constant, (4πε0)−1 (sometimes ke or k), andthe Boltzmann constant, kB (sometimes k).
Planck units are sometimes called "God's units",[1][2] since Planck units are free of anthropocentric arbitrariness. Natural units help physicists to reframe questions. Frank Wilczek puts it succinctly: Boltzmann constant. The Boltzmann constant (kB or k), named after Ludwig Boltzmann, is a physical constant relating energy at the individual particle level with temperature. It is the gas constant R divided by the Avogadro constant NA: It has the same dimension (energy divided by temperature) as entropy. The accepted value in SI units is 1.3806488(13)×10−23 J/K. Bridge from macroscopic to microscopic physics[edit] where R is the gas constant (8.314 4621(75) J K−1 mol−1[1]). Introducing the Boltzmann constant transforms the ideal gas law into an alternative form: The left-hand side of the equation is a macroscopic amount of pressure-volume energy representing the state of the bulk gas.
Role in the equipartition of energy[edit] Given a thermodynamic system at an absolute temperature T, the thermal energy carried by each microscopic "degree of freedom" in the system is on the order of magnitude of kBT/2 (i. e., about 2.07×10−21 J, or 0.013 eV, at room temperature). Application to simple gas thermodynamics[edit] Coulomb's law. Value of the constant[edit] The exact value of Coulomb's constant ke comes from three of the fundamental, invariant quantities that define free space in the SI system: the speed of light c0 , magnetic permeability μ0 , and electric permittivity ε0 , related by Maxwell as: Use of Coulomb's constant[edit] Coulomb's constant is used in many electric equations, although it is sometimes expressed as the following product of the vacuum permittivity constant: Some examples of use of Coulomb's constant are the following: Coulomb's law: Electric potential energy: Electric field: See also[edit] References[edit]
Planck constant. Plaque at the Humboldt University of Berlin: "Max Planck, discoverer of the elementary quantum of action h, taught in this building from 1889 to 1928. " In 1905 the value (E), the energy of a charged atomic oscillator, was theoretically associated with the energy of the electromagnetic wave itself, representing the minimum amount of energy required to form an electromagnetic field (a "quantum"). Further investigation of quanta revealed behaviour associated with an independent unit ("particle") as opposed to an electromagnetic wave and was eventually given the term photon. The Planck relation now describes the energy of each photon in terms of the photon's frequency. This energy is extremely small in terms of ordinary experience. Since the frequency , wavelength λ, and speed of light c are related by λν = c, the Planck relation for a photon can also be expressed as The above equation leads to another relationship involving the Planck constant.
Value[edit] Significance of the value[edit] Gravitational constant. The gravitational constant, approximately 6.67×10−11 N·(m/kg)2 and denoted by letter G, is an empirical physical constant involved in the calculation(s) of gravitational force between two bodies. It usually appears in Sir Isaac Newton's law of universal gravitation, and in Albert Einstein's theory of general relativity.
It is also known as the universal gravitational constant, Newton's constant, and colloquially as Big G.[1] It should not be confused with "little g" (g), which is the local gravitational field (equivalent to the free-fall acceleration[2]), especially that at the Earth's surface. Laws and constants[edit] According to the law of universal gravitation, the attractive force (F) between two bodies is directly proportional to the product of their masses (m1 and m2), and inversely proportional to the square of the distance, r, (inverse-square law) between them: The constant of proportionality, G, is the gravitational constant. with relative standard uncertainty 1.2×10−4.[4] .
And. Speed of light.