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ATLAS (A Toroidal LHC ApparatuS) is one of the five particle detector experiments (ALICE, ATLAS, CMS, TOTEM, and LHCb) being constructed at the Large Hadron Collider, a new particle accelerator at CERN in Switzerland. It will be 45 metres long and 25 metres in diameter, and will weigh about 7,000 tonnes. The project involves roughly 2,000 scientists and engineers at 151 institutions in 34 countries. The construction is scheduled to be completed in 2007. The experiment is expecte ...

Including:

• ATLAS experiment - Background
• ATLAS experiment - Physics program
• ATLAS experiment - Components
• ATLAS experiment - Inner Detector
• ATLAS experiment - Calorimeters
• ATLAS experiment - Muon spectrometer
• ATLAS experiment - Magnet system
• ATLAS experiment - Data systems and analysis

Read more here: » ATLAS experiment: Encyclopedia - ATLAS experiment

Related topics: CPT symmetry CKM matrix CP symmetry Chirality Each quark is assigned a baryon number, B  =  1/3, and a vanishing lepton number L  =  0. They have fractional electric charge, Q, either Q  =  +2/3 or Q  =  −1/3. The former are called up-type quarks, the latter, down-type quarks. Each quark is assigned a weak isospin: Tz  =  +1/2 for an up-type quar ...

See also:

Quark, Quark - Free quarks, Quark - Confinement and quark properties, Quark - Flavour, Quark - Spin, Quark - Colour, Quark - Quark masses, Quark - Current quark mass, Quark - Valence quark mass, Quark - Heavy quark masses, Quark - Properties of quarks, Quark - Antiquarks, Quark - Substructure, Quark - History

Read more here: » Quark: Encyclopedia II - Quark - Flavour

On the left is the CKM Matrix along with a vector of strong force eigenstates of the quarks, and on the right is the weak force eigenstates of the quarks. The CKM matrix describes the probability of a transition from one quark q to another quark q' . This transition is proportional to . Experimentally, the magnitudes of the values in the matrix have been found to be roughly: ...

See also:

CKM matrix, CKM matrix - The matrix, CKM matrix - Counting, CKM matrix - Observations and predictions, CKM matrix - Weak universality, CKM matrix - The unitarity triangles

Read more here: » CKM matrix: Encyclopedia II - CKM matrix - The matrix

The data shows five isoscalar resonances— f0(600), f0(980), f0(1370), f0(1500) and f0(1710) Of these the f0(600) is usually identified with the σ of chiral models. The decays and production of f0(1710) give strong evidence that it is also a meso ...

See also:

Exotic meson, Exotic meson - Lattice predictions, Exotic meson - The 0^{+ +} states, Exotic meson - Glueball candidate, Exotic meson - Tetraquark candidate, Exotic meson - The 2^{+ +} states, Exotic meson - The 1^{- +} exotics and other states

Read more here: » Exotic meson: Encyclopedia II - Exotic meson - The 0^{+ +} states

The ATLAS detector consists of a series of ever-larger concentric cylinders around the interaction point where the proton beams from the LHC collide. It can be divided into four major parts: the Inner Detector, the calorimeters, the muon spectrometer and the magnet systems. Each of these is in turn made of multiple layers. The detectors are complementary: the Inner Detector tracks particles precisely, the calorimeters measure the energy of easily stopped particles, and the muon system makes additional measurements of highly penetrating muons. The two magnet systems bend charged particles in the Inner Detector and the muon spect ...

See also:

ATLAS experiment, ATLAS experiment - Background, ATLAS experiment - Physics program, ATLAS experiment - Components, ATLAS experiment - Inner Detector, ATLAS experiment - Calorimeters, ATLAS experiment - Muon spectrometer, ATLAS experiment - Magnet system, ATLAS experiment - Data systems and analysis

Read more here: » ATLAS experiment: Encyclopedia II - ATLAS experiment - Components

The notion of quarks evolved out of a classification of hadrons developed independently in 1961 by Murray Gell-Mann and Kazuhiko Nishijima, which nowadays goes by the name of the quark model. The scheme grouped together particles with isospin and strangeness using an unitary symmetry derived from current algebra, which we today recognise as part of the approximate chiral symmetry of QCD. This is a global flavour SU(3) symmetry, which should not be confuse ...

See also:

Quark, Quark - Free quarks, Quark - Confinement and quark properties, Quark - Flavour, Quark - Spin, Quark - Colour, Quark - Quark masses, Quark - Current quark mass, Quark - Valence quark mass, Quark - Heavy quark masses, Quark - Properties of quarks, Quark - Antiquarks, Quark - Substructure, Quark - History

Read more here: » Quark: Encyclopedia II - Quark - History

The remaining constraints of unitarity of the CKM-matrix can be written in the form For any fixed i and j, this is a constraint on three complex numbers, one for each k, which says that these numbers form the vertices of a triangle in the complex plane. There are six choices of i and j, and hence six such triangles, each of which is called an unitary triangle. Their shapes can be very different, but they all have the same area, which can be related to ...

See also:

CKM matrix, CKM matrix - The matrix, CKM matrix - Counting, CKM matrix - Observations and predictions, CKM matrix - Weak universality, CKM matrix - The unitarity triangles

Read more here: » CKM matrix: Encyclopedia II - CKM matrix - The unitarity triangles

The constraints of unitarity of the CKM-matrix on the diagonal terms can be written as ∑ | Vij | 2 = 1 j for all generations i. This implies that the sum of all couplings of any of the up-type quarks to all the down-type quarks is the same for all generations. This relation is called weak un ...

See also:

CKM matrix, CKM matrix - The matrix, CKM matrix - Counting, CKM matrix - Observations and predictions, CKM matrix - Weak universality, CKM matrix - The unitarity triangles

Read more here: » CKM matrix: Encyclopedia II - CKM matrix - Weak universality

Although one speaks of quark mass in the same way as the mass of any other particle, the notion of mass for quarks is complicated by the fact that quarks cannot be found free in nature. As a result, the notion of a quark mass is a theoretical construct, which makes sense only when one specifies exactly the procedure used to define it. Quark - Current quark mass. The approximate chiral symmetry of QCD, for example, allows one to define the ratio between various (up, down and strange) quark masses thr ...

See also:

Quark, Quark - Free quarks, Quark - Confinement and quark properties, Quark - Flavour, Quark - Spin, Quark - Colour, Quark - Quark masses, Quark - Current quark mass, Quark - Valence quark mass, Quark - Heavy quark masses, Quark - Properties of quarks, Quark - Antiquarks, Quark - Substructure, Quark - History

Read more here: » Quark: Encyclopedia II - Quark - Quark masses

The idea of Cabibbo originated from a need to explain two observed phenomena: the transitions u↔d and e↔νe, μ↔νμ had similar amplitudes. the transitions with change in strangeness ΔS=1 had amplitudes equal to 1/4 of those with ΔS=0. Cabibbo's solution consisted of postulating weak universality to resolve issue 1, along with a mixing angle θc, now called the Cabibbo angle, b ...

See also:

CKM matrix, CKM matrix - The matrix, CKM matrix - Counting, CKM matrix - Observations and predictions, CKM matrix - Weak universality, CKM matrix - The unitarity triangles

Read more here: » CKM matrix: Encyclopedia II - CKM matrix - Observations and predictions

Every subatomic particle is completely described by a small set of quantum numbers such as its spin J, parity P, and mass m. Usually these properties are directly determined by experiments. However, confinement makes it impossible to measure these properties of quarks. Instead, they must be inferred from measurable properties of the composite particles which are made up of quarks. Such inferences are most easily ...

See also:

Quark, Quark - Free quarks, Quark - Confinement and quark properties, Quark - Flavour, Quark - Spin, Quark - Colour, Quark - Quark masses, Quark - Current quark mass, Quark - Valence quark mass, Quark - Heavy quark masses, Quark - Properties of quarks, Quark - Antiquarks, Quark - Substructure, Quark - History

Read more here: » Quark: Encyclopedia II - Quark - Confinement and quark properties

The first cyclotron, an early type of particle accelerator, was built by Ernest O. Lawrence in 1931, with a radius of just a few centimetres and a particle energy of 1 MeV. Since then, accelerators have grown enormously in the quest to produce new particles of greater and greater mass. As accelerators have grown, so too has the list of known particles that they might be used to investigate. The most comprehensive model of particle interactions available today is known as the Standard Model; except for the Higgs boson, all of the particles in ...

See also:

ATLAS experiment, ATLAS experiment - Background, ATLAS experiment - Physics program, ATLAS experiment - Components, ATLAS experiment - Inner Detector, ATLAS experiment - Calorimeters, ATLAS experiment - Muon spectrometer, ATLAS experiment - Magnet system, ATLAS experiment - Data systems and analysis

Read more here: » ATLAS experiment: Encyclopedia II - ATLAS experiment - Background

ATLAS is intended to investigate many different types of physics that might become detectable in the energetic collisions of the LHC. Some of these are confirmations or improved measurements of the Standard Model, while many others are searches for new physical theories. One of the most important goals of ATLAS is to investigate the final missing piece of the Standard Model, the Higgs boson. The Higgs mechanism, which includes the Higgs boson, is invoked to give masses to elementary particles, giving rise to the differences between th ...

See also:

ATLAS experiment, ATLAS experiment - Background, ATLAS experiment - Physics program, ATLAS experiment - Components, ATLAS experiment - Inner Detector, ATLAS experiment - Calorimeters, ATLAS experiment - Muon spectrometer, ATLAS experiment - Magnet system, ATLAS experiment - Data systems and analysis

Read more here: » ATLAS experiment: Encyclopedia II - ATLAS experiment - Physics program

Lattice QCD predictions for glueballs are now fairly stable, at least when virtual quarks are neglected. The two lowest states are 0+ + with mass of 1611±163 MeV 2+ + with mass of 2232±310 MeV The 0- + and exotic glueballs such as 0- - are all expected to lie above 2 GeV. Glueballs are ...

See also:

Exotic meson, Exotic meson - Lattice predictions, Exotic meson - The 0^{+ +} states, Exotic meson - Glueball candidate, Exotic meson - Tetraquark candidate, Exotic meson - The 2^{+ +} states, Exotic meson - The 1^{- +} exotics and other states

Read more here: » Exotic meson: Encyclopedia II - Exotic meson - Lattice predictions

The two isovector exotics π1(1400) and π1(1600) seems to be well established experimentally. They are clearly not glueballs, but could be either a tetraquark or a hybrid. The evidence for such assignments is weak. The 0- + π(1800), 1- - ρ(1900) and the 2- + η2<(1870) are fairly well identified states, which have been tentatively identified as hybrids by some authors. If this identification is correct, then it is a remarkable agree ...

See also:

Exotic meson, Exotic meson - Lattice predictions, Exotic meson - The 0^{+ +} states, Exotic meson - Glueball candidate, Exotic meson - Tetraquark candidate, Exotic meson - The 2^{+ +} states, Exotic meson - The 1^{- +} exotics and other states

Read more here: » Exotic meson: Encyclopedia II - Exotic meson - The 1^{- +} exotics and other states

Since quarks are fermions, the Pauli exclusion principle implies that the three valence quarks must be in an antisymmetric combination in a baryon. However, the charge Q =  2 baryon, Δ++ (which is one of four isospin Iz  =  3/2 baryons) can only be made of three u quarks with parallel spins. Since this configuration is symmetric under interchange of the quarks, it implies that there exists another internal quantum number, which would then make the combination antisymmetri ...

See also:

Quark, Quark - Free quarks, Quark - Confinement and quark properties, Quark - Flavour, Quark - Spin, Quark - Colour, Quark - Quark masses, Quark - Current quark mass, Quark - Valence quark mass, Quark - Heavy quark masses, Quark - Properties of quarks, Quark - Antiquarks, Quark - Substructure, Quark - History

Read more here: » Quark: Encyclopedia II - Quark - Colour