LHCb experimentThe LHCb (Large Hadron Collider beauty) experiment is a particle physics detector experiment collecting data at the Large Hadron Collider at CERN. LHCb is a specialized b-physics experiment, designed primarily to measure the parameters of CP violation in the interactions of b-hadrons (heavy particles containing a bottom quark). Such studies can help to explain the matter-antimatter asymmetry of the Universe. The detector is also able to perform measurements of production cross sections, exotic hadron spectroscopy, charm physics and electroweak physics in the forward region.
MesonIn particle physics, a meson (ˈmiːzɒn,_ˈmɛzɒn) is a type of hadronic subatomic particle composed of an equal number of quarks and antiquarks, usually one of each, bound together by the strong interaction. Because mesons are composed of quark subparticles, they have a meaningful physical size, a diameter of roughly one femtometre (10^−15 m), which is about 0.6 times the size of a proton or neutron. All mesons are unstable, with the longest-lived lasting for only a few tenths of a nanosecond.
Rho mesonIn particle physics, a rho meson is a short-lived hadronic particle that is an isospin triplet whose three states are denoted as _Rho+, _Rho0 and _Rho-. Along with pions and omega mesons, the rho meson carries the nuclear force within the atomic nucleus. After the pions and kaons, the rho mesons are the lightest strongly interacting particle, with a mass of 775.45MeV for all three states. The rho mesons have a very short lifetime and their decay width is about 145MeV with the peculiar feature that the decay widths are not described by a Breit–Wigner form.
Vector mesonIn high energy physics, a vector meson is a meson with total spin 1 and odd parity (usually noted as JP = 1−). Vector mesons have been seen in experiments since the 1960s, and are well known for their spectroscopic pattern of masses. The vector mesons contrast with the pseudovector mesons, which also have a total spin 1 but instead have even parity. The vector and pseudovector mesons are also dissimilar in that the spectroscopy of vector mesons tends to show nearly pure states of constituent quark flavors, whereas pseudovector mesons and scalar mesons tend to be expressed as composites of mixed states.
Omega mesonThe omega meson (_Omega meson) is a flavourless meson formed from a superposition of an up quark–antiquark and a down quark–antiquark pair. It is part of the vector meson nonet and mediates the nuclear force along with pions and rho mesons. The most common decay mode for the ω meson is _Pion+_Pion0_Pion- at 89.2±0.7%, followed by _Pion0_Gamma at 8.34±0.26%. The quark composition of the _Omega meson meson can be thought of as a mix between _up quark_up antiquark, _down quark_down antiquark and _strange quark_strange antiquark states, but it is very nearly a pure symmetric _up quark_up antiquark-_down quark_down antiquark state.
J/psi mesonThe _J/psi (J/psi) meson ˈdʒeɪ_ˈsaɪ_ˈmiːzɒn is a subatomic particle, a flavor-neutral meson consisting of a charm quark and a charm antiquark. Mesons formed by a bound state of a charm quark and a charm anti-quark are generally known as "charmonium" or psions. The _J/Psi is the most common form of charmonium, due to its spin of 1 and its low rest mass. The _J/Psi has a rest mass of 3.0969GeV/c2, just above that of the _charmed eta (2.9836GeV/c2), and a mean lifetime of 7.2e-21s.
Scalar mesonIn high energy physics, a scalar meson is a meson with total spin 0 and even parity (usually noted as JP=0+). Compare to pseudoscalar meson. The first known scalar mesons have been observed since the late 1950s, with observations of numerous light states and heavier states proliferating since the 1980s. Scalar mesons are most often observed in proton-antiproton annihilation, radiative decays of vector mesons, and meson-meson scattering.
Baryon asymmetryIn physical cosmology, the baryon asymmetry problem, also known as the matter asymmetry problem or the matter–antimatter asymmetry problem, is the observed imbalance in baryonic matter (the type of matter experienced in everyday life) and antibaryonic matter in the observable universe. Neither the standard model of particle physics nor the theory of general relativity provides a known explanation for why this should be so, and it is a natural assumption that the universe is neutral with all conserved charges.
KaonIn particle physics, a kaon (ˈkeɪ.ɒn), also called a K meson and denoted _Kaon, is any of a group of four mesons distinguished by a quantum number called strangeness. In the quark model they are understood to be bound states of a strange quark (or antiquark) and an up or down antiquark (or quark). Kaons have proved to be a copious source of information on the nature of fundamental interactions since their discovery in cosmic rays in 1947.
TetraquarkA tetraquark, in particle physics, is an exotic meson composed of four valence quarks. A tetraquark state has long been suspected to be allowed by quantum chromodynamics, the modern theory of strong interactions. A tetraquark state is an example of an exotic hadron which lies outside the conventional quark model classification. A number of different types of tetraquark have been observed. Several tetraquark candidates have been reported by particle physics experiments in the 21st century.
PentaquarkA pentaquark is a human-made subatomic particle, consisting of four quarks and one antiquark bound together; they are not known to occur naturally, or exist outside of experiments specifically carried out to create them. As quarks have a baryon number of + 1/3, and antiquarks of − 1/3, the pentaquark would have a total baryon number of 1, and thus would be a baryon. Further, because it has five quarks instead of the usual three found in regular baryons ( 'triquarks'), it is classified as an exotic baryon.
LuminosityLuminosity is an absolute measure of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object over time. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a star, galaxy, or other astronomical objects. In SI units, luminosity is measured in joules per second, or watts. In astronomy, values for luminosity are often given in the terms of the luminosity of the Sun, L⊙.
Sampling (statistics)In statistics, quality assurance, and survey methodology, sampling is the selection of a subset or a statistical sample (termed sample for short) of individuals from within a statistical population to estimate characteristics of the whole population. Statisticians attempt to collect samples that are representative of the population. Sampling has lower costs and faster data collection compared to recording data from the entire population, and thus, it can provide insights in cases where it is infeasible to measure an entire population.
B-factoryIn particle physics, a B-factory, or sometimes a beauty factory, is a particle collider experiment designed to produce and detect a large number of B mesons so that their properties and behavior can be measured with small statistical uncertainty. Tau leptons and D mesons are also copiously produced at B-factories. A sort of "prototype" or "precursor" B-factory was the HERA-B experiment at DESY that was planned to study B-meson physics in the 1990–2000s, before the actual B-factories were constructed/operational.
Stratified samplingIn statistics, stratified sampling is a method of sampling from a population which can be partitioned into subpopulations. In statistical surveys, when subpopulations within an overall population vary, it could be advantageous to sample each subpopulation (stratum) independently. Stratification is the process of dividing members of the population into homogeneous subgroups before sampling. The strata should define a partition of the population.
NeutrinoA neutrino (njuːˈtriːnoʊ ; denoted by the Greek letter ν) is a fermion (an elementary particle with spin of 1 /2) that interacts only via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass is so small (-ino) that it was long thought to be zero. The rest mass of the neutrino is much smaller than that of the other known elementary particles excluding massless particles.
ProtonA proton is a stable subatomic particle, symbol _Proton, H+, or 1H+ with a positive electric charge of +1 e (elementary charge). Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton-to-electron mass ratio). Protons and neutrons, each with masses of approximately one atomic mass unit, are jointly referred to as "nucleons" (particles present in atomic nuclei). One or more protons are present in the nucleus of every atom.
BaryogenesisIn physical cosmology, baryogenesis (also known as baryosynthesis) is the physical process that is hypothesized to have taken place during the early universe to produce baryonic asymmetry, i.e. the imbalance of matter (baryons) and antimatter (antibaryons) in the observed universe. One of the outstanding problems in modern physics is the predominance of matter over antimatter in the universe. The universe, as a whole, seems to have a nonzero positive baryon number density.
Simple random sampleIn statistics, a simple random sample (or SRS) is a subset of individuals (a sample) chosen from a larger set (a population) in which a subset of individuals are chosen randomly, all with the same probability. It is a process of selecting a sample in a random way. In SRS, each subset of k individuals has the same probability of being chosen for the sample as any other subset of k individuals. A simple random sample is an unbiased sampling technique. Simple random sampling is a basic type of sampling and can be a component of other more complex sampling methods.
Absolute magnitudeAbsolute magnitude (M) is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it were viewed from a distance of exactly , without extinction (or dimming) of its light due to absorption by interstellar matter and cosmic dust. By hypothetically placing all objects at a standard reference distance from the observer, their luminosities can be directly compared among each other on a magnitude scale.
