|
Fitch–Cronin Experiment
In particle physics, CP violation is a violation of CP-symmetry (or charge conjugation parity symmetry): the combination of C-symmetry (charge conjugation symmetry) and P-symmetry ( parity symmetry). CP-symmetry states that the laws of physics should be the same if a particle is interchanged with its antiparticle (C-symmetry) while its spatial coordinates are inverted ("mirror" or P-symmetry). CP violation is only observed in the weak interaction. The discovery of CP violation in 1964 in the decays of neutral kaons resulted in the Nobel Prize in Physics in 1980 for its discoverers James Cronin and Val Fitch. CP violation was subsequently discovered in many other meson decays. In 2025, the LHCb experiment discovered CP violation in baryons. There is some evidence CP violation may occur in neutrino interactions. It is important to the matter-antimatter asymmetry problem, the strong CP problem, and in the study of weak interactions in particle physics. Under the CPT theorem, ev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Physics
Particle physics or high-energy physics is the study of Elementary particle, fundamental particles and fundamental interaction, forces that constitute matter and radiation. The field also studies combinations of elementary particles up to the scale of protons and neutrons, while the study of combinations of protons and neutrons is called nuclear physics. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) and bosons (force-carrying particles). There are three Generation (particle physics), generations of fermions, although ordinary matter is made only from the first fermion generation. The first generation consists of Up quark, up and down quarks which form protons and neutrons, and electrons and electron neutrinos. The three fundamental interactions known to be mediated by bosons are electromagnetism, the weak interaction, and the strong interaction. Quark, Quarks cannot exist on their own but form hadrons. Hadrons that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conservation Of Momentum
In Newtonian mechanics, momentum (: momenta or momentums; more specifically linear momentum or translational momentum) is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. If is an object's mass and is its velocity (also a vector quantity), then the object's momentum (from Latin '' pellere'' "push, drive") is: \mathbf = m \mathbf. In the International System of Units (SI), the unit of measurement of momentum is the kilogram metre per second (kg⋅m/s), which is dimensionally equivalent to the newton-second. Newton's second law of motion states that the rate of change of a body's momentum is equal to the net force acting on it. Momentum depends on the frame of reference, but in any inertial frame of reference, it is a ''conserved'' quantity, meaning that if a closed system is not affected by external forces, its total momentum does not change. Momentum is also conserved in special relativity (with a m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Reaction
A chemical reaction is a process that leads to the chemistry, chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an Gibbs free energy, energy change as new products are generated. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the Atomic nucleus, nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive Chemical element, elements where both electronic and nuclear changes can occur. The substance (or substances) initially involved in a chemical reaction are called reagent, reactants or reagents. Chemical reactions are usually characterized by a chemical change, and they yield one or more Product (c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parity (physics)
In physics, a parity transformation (also called parity inversion) is the flip in the sign of ''one'' spatial coordinate. In three dimensions, it can also refer to the simultaneous flip in the sign of all three spatial coordinates (a point reflection): \mathbf: \beginx\\y\\z\end \mapsto \begin-x\\-y\\-z\end. It can also be thought of as a test for chirality of a physical phenomenon, in that a parity inversion transforms a phenomenon into its mirror image. All fundamental interactions of elementary particles, with the exception of the weak interaction, are symmetric under parity transformation. As established by the Wu experiment conducted at the US National Bureau of Standards by Chinese-American scientist Chien-Shiung Wu, the weak interaction is chiral and thus provides a means for probing chirality in physics. In her experiment, Wu took advantage of the controlling role of weak interactions in radioactive decay of atomic isotopes to establish the chirality of the weak f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Progress In Particle And Nuclear Physics
Progress is movement towards a perceived refined, improved, or otherwise desired state. It is central to the philosophy of progressivism, which interprets progress as the set of advancements in technology, science, and social organization efficiency – the latter being generally achieved through direct societal action, as in social enterprise or through activism, but being also attainable through natural sociocultural evolution – that progressivism holds all human societies should strive towards. The concept of progress was introduced in the early-19th-century social theories, especially social evolution as described by Auguste Comte and Herbert Spencer. It was present in the Enlightenment's philosophies of history. As a goal, social progress has been advocated by varying realms of political ideologies with different theories on how it is to be achieved. Measuring progress Specific indicators for measuring progress can range from economic data, technical innovations, chang ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physics Today
''Physics Today'' is the membership magazine of the American Institute of Physics. First published in May 1948, it is issued on a monthly schedule, and is provided to the members of ten physics societies, including the American Physical Society. It is also available to non-members as a paid annual subscription. The magazine informs readers about important developments in overview articles written by experts, shorter review articles written internally by staff, and also discusses issues and events of importance to the science community in politics, education, and other fields. The magazine provides a historical resource of events associated with physics. For example it discussed debunking the physics of the Star Wars program of the 1980s, and the state of physics in China and the Soviet Union during the 1950s and 1970s. According to the ''Journal Citation Reports'', the journal has a 2017 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic jou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fermilab
Fermi National Accelerator Laboratory (Fermilab), located in Batavia, Illinois, near Chicago, is a United States Department of Energy United States Department of Energy National Labs, national laboratory specializing in high-energy particle physics. Fermilab's Main Injector, two miles (3.3 km) in circumference, is the laboratory's most powerful particle accelerator. The accelerator complex that feeds the Main Injector is under upgrade, and construction of the first building for the new PIP-II linear accelerator began in 2020. Until 2011, Fermilab was the home of the 6.28 km (3.90 mi) circumference Tevatron accelerator. The ring-shaped tunnels of the Tevatron and the Main Injector are visible from the air and by satellite. Fermilab aims to become a world center in neutrino physics. It is the host of the multi-billion dollar Deep Underground Neutrino Experiment (DUNE) now under construction. The project has suffered delays and, in 2022, the journals ''Science'' and ''Sc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CERN
The European Organization for Nuclear Research, known as CERN (; ; ), is an intergovernmental organization that operates the largest particle physics laboratory in the world. Established in 1954, it is based in Meyrin, western suburb of Geneva, on the France–Switzerland border. It comprises #Member states and budget, 24 member states. Israel, admitted in 2013, is the only full member geographically out of Europe. CERN is an official United Nations General Assembly observers#Intergovernmental organizations, United Nations General Assembly observer. The acronym CERN is also used to refer to the laboratory; in 2023, it had 2,666 scientific, technical, and administrative staff members, and hosted about 12,370 users from institutions in more than 80 countries. In 2016, CERN generated 49 Byte#Multiple-byte units, petabytes of data. CERN's main function is to provide the particle accelerators and other infrastructure needed for high-energy physics research – consequently, numer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CPLEAR Experiment
The CPLEAR experiment used the antiproton Particle beam, beam of the LEAR facility – Low-Energy Antiproton Ring which operated at CERN from 1982 to 1996 – to produce neutral kaon''s'' through proton-antiproton annihilation in order to study ''CP violation, CP'', ''T symmetry, T'' and ''CPT symmetry, CPT'' violation in the neutral kaon system. Background According to the theory of the Big Bang, matter and antimatter would have existed in the same amount at the beginning of the Universe. If this was true, particle''s'' and antiparticle''s'' would have annihilated each other, creating photon''s'', and thus the Universe would have been only compounded by light (one particle of matter for 1018 photons). However, only matter has remained and at a rate of one billion times more particles than expected. What happened then, for the antimatter to disappear in favor of matter? A possible answer to this question is baryogenesis, the hypothetical physical process that took place during the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
T-symmetry
T-symmetry or time reversal symmetry is the theoretical symmetry of physical laws under the transformation of time reversal, : T: t \mapsto -t. Since the second law of thermodynamics states that entropy increases as time flows toward the future, in general, the macroscopic universe does not show symmetry under time reversal. In other words, time is said to be non-symmetric, or asymmetric, except for special equilibrium states when the second law of thermodynamics predicts the time symmetry to hold. However, quantum noninvasive measurements are predicted to violate time symmetry even in equilibrium, contrary to their classical counterparts, although this has not yet been experimentally confirmed. Time ''asymmetries'' (see Arrow of time) generally are caused by one of three categories: # intrinsic to the dynamic physical law (e.g., for the weak force) # due to the initial conditions of the universe (e.g., for the second law of thermodynamics) # due to measurements (e.g., for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Field Theory
In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines Field theory (physics), field theory and the principle of relativity with ideas behind quantum mechanics. QFT is used in particle physics to construct physical models of subatomic particles and in condensed matter physics to construct models of quasiparticles. The current standard model of particle physics is based on QFT. History Quantum field theory emerged from the work of generations of theoretical physicists spanning much of the 20th century. Its development began in the 1920s with the description of interactions between light and electrons, culminating in the first quantum field theory—quantum electrodynamics. A major theoretical obstacle soon followed with the appearance and persistence of various infinities in perturbative calculations, a problem only resolved in the 1950s with the invention of the renormalization procedure. A second major barrier came with QFT's apparent inabili ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CPT Symmetry
Charge, parity, and time reversal symmetry is a fundamental symmetry of physical laws under the simultaneous transformations of charge conjugation (C), parity transformation (P), and time reversal (T). CPT is the only combination of C, P, and T that is observed to be an exact symmetry of nature at the fundamental level. The CPT theorem says that CPT symmetry holds for all physical phenomena, or more precisely, that any Lorentz invariant local quantum field theory with a Hermitian Hamiltonian must have CPT symmetry. In layman terms, this stipulates that an antimatter, mirrored, and time reversed universe would behave exactly the same as our regular universe. History The CPT theorem appeared for the first time, implicitly, in the work of Julian Schwinger in 1951 to prove the connection between spin and statistics. In 1954, Gerhart Lüders and Wolfgang Pauli derived more explicit proofs, so this theorem is sometimes known as the Lüders–Pauli theorem. At about the same t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
