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Topic: CP symmetry

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Strong CP problem

Kaon

CKM matrix

Weak nuclear force

Edward Mills Purcell

List of particles

Hadron

Neutrino

Large Hadron Collider

CPT symmetry

CP-symmetry - Wikipedia, the free encyclopedia CP-symmetry is a symmetry obtained by a combination of the C-symmetry and the P-symmetry. The strong CP problem is the question of why no such violation is detected even though the theory in principle allows for it. The CP violation of the Standard model is incorporated by including a complex phase in the CKM matrix. en.wikipedia.org /wiki/CP-symmetry

CP violation Comparison Table abstraction > mathematical concept > symmetry breaking > CP violation A reaction between subatomic particles is said to be a "CP violating" reaction if the reaction produces a different result when the electrical charges of the particles are changed to their opposites and the mirror image of the particle trajectories is used. A broken symmetry condition differs from chaos in that its parts can in theory be united in a symmetrical whole, like the pieces of a jigsaw puzzle. www.site.uottawa.ca:4321 /astronomy/CPviolation_table.html

CPT Invariance It was thought for a time that CP (parity transformation plus charge conjugation) would always leave a system invariant, but the notable example of the neutral kaons has shown a slight violation of CP symmetry. We are left with the combination of all three, CPT, a profound symmetry consistent with all known experimental observations. The small violation of CP symmetry suggests some departure from T symmetry in some weak interaction processes since CPT invariance seems to be on very firm ground. hyperphysics.phy-astr.gsu.edu /hbase/particles/cpt.html

Physics Today May 2001 The only clear evidence we have for the violation of CP symmetry in nature--aside from the cosmic preponderance of matter over antimatter--comes from the decay of neutral K mesons. is the CP eigenvalue of the decay eigenstate. CP denotes the combined operation of charge conjugation (C), the replacement of particles by their antiparticles, and parity inversion (P). physicstoday.org /vol-54/iss-5/p17.html

Physics News Update Experiments in the 1950s and 60s showed that interactions via the weak nuclear force not only can violate the C and P propositions, but even the combined CP symmetry, and it is this fact, like a rarely expressed defective gene, which over cosmological time leads to the apparent large-scale extinction of antimatter. CP violation was first studied in the 60s with the asymmetrical decays of K mesons, which possess strange quarks (for the latest on CP violation in K's see Update 420). The chief parameter used to indicate CP violation is called sin (2 beta), and BaBar's measured value is 0.34, with an uncertainty of 0.20, an accuracy about twice as good as the previous value (Update 497). www.aip.org /enews/physnews/2001/525.html

C-symmetry - Bvio It was believed for some time that this could be combined with the parity-inversion transformation (see P-symmetry) to preserve a so-called CP-symmetry. However, this symmetry appears to be violated in observation, owing to the fact that (at least the nearby part of) our physical universe is made up of matter and not anti-matter. C-symmetry means the symmetry of physical laws over a charge-inversion transformation. bvio.ngic.re.kr /Bvio/index.php/C-symmetry

Science Fair Projects - T-symmetry One of the criteria is that CP and hence T-symmetry is violated. The reason for believing this is an argument by physicist Andrei Sakharov who developed the criteria for there to be a difference in the amount of matter and anti-matter in the universe assuming that the universe did not start out with this asymmetry. T-symmetry is the symmetry of physical laws under a time-reversal transformation. www.all-science-fair-projects.com /science_fair_projects_encyclopedia/T-symmetry

CP violation The violation of CP symmetry, taken as a kind of proof of the CPT theorem, enables physicists to make an absolute distinction between matter and antimatter. With a series of debatable but plausible assumptions, it can be demonstrated that the observed matter-antimatter ratio may have been produced by the occurrence of CP violation in the first seconds after the "big bang," the violent explosion that is thought to have resulted in the formation of the universe. Furthermore, the model is consistent with all measurements of CP violation and its properties. www.britannica.com /nobel/micro/148_90.html

CERN Courier - New precision result on CP v - IOP Publishing - article In CP (charge/parity) symmetry the physics of left-handed particles is the same as that of right-handed antiparticles. The latest precision measurement of CP violation, matter-antimatter asymmetry, by the big NA48 experiment at CERN underlines the importance of understanding this delicate mechanism, which probably played a major role in shaping the particle scenario that emerged from the Big Bang. CP violation is not simply due to the subtle mixing of neutral particles and antiparticles. www.cerncourier.com /main/article/40/4/3

KOPIO - Investigations Into the Heart of Matter Since CP symmetry violation is one of the most important outstanding issues in the study of elementary particle physics with profound implications on the relationship between the quarks, and possibly also on the origin of matter in the universe, it is one of the main areas of worldwide activity in particle physics. While CP symmetry violation had only been observed in K meson decays, during the past year, great international efforts involving several thousand researchers and new accelerators and detectors have uncovered similar effects using the heavier B meson. Since 1964, in experiments involving the decays of neutral K mesons, charge-parity (CP) and time reversal (T) symmetry violations have been observed lending support to the consistency of Sakharov's hypothesis. www.bnl.gov /rsvp/symmetry.htm

Direct CP symmetry violation CP symmetry violation is one of the three conditions necessary to create the matter-antimatter asymmetry that can be observed in the Universe. The Standard Model, a theory that is firmly established in particle physics, explains this CP symmetry violation using a mechanism based on the existence of three families of quarks. This model also predicts another CP symmetry violation mechanism, then referred to as "direct violation" and which is even more rare. www.cnrs.fr /cw/en/pres/compress/cpviolation.html

Nature's flawed mirror (July 2003) - Physics World - PhysicsWeb Although CP violation is still thought to be a key ingredient in the explanation of the matter-antimatter asymmetry in the universe, the amount of CP violation in the Standard Model is insufficient to account for all of it. A D Sakharov 1967 Violation of CP invariance, C asymmetry, and baryon asymmetry of the universe Pis. This demonstrated for the first time that the combined CP symmetry is violated by the weak interaction. physicsweb.org /article/world/16/7/8/1

CP-Violation, The Theory From the symmetry of the quantum-mechanical equations of weak decay under reflection, it was possible to show that this decay was impossible. The most interesting case about the symmetries is the symmetry of reflections in space and just by intuition about laws of physics we can say that they have such a symmetry. The symmetries of physical laws is most interesting in the case of quantum mechanics, as for each rules of symmetry there is a corresponding conservation law (Noether's Theorem). dept.physics.upenn.edu /~gladney/babar/cp_violation.html

YkS_EDM_web_010210.htm CP violation is the only known mechanism that could explain the matter antimatter asymmetry found in the universe. Among the not yet understood phenomena are the reasons for parity violation, the particle masses, the violation of the CP symmetry. If CPT is assumed to be a valid unbroken symmetry, a permanent EDM would hence be a signature of CP violation. www.bnl.gov /edm/YkS_EDM_web_010210.htm

Open Questions: CP Symmetry Violation A very slight violation of CP symmetry is known to exist, and the existence of matter in the universe seems to depend on it. An analogy illuminates the problem of CP symmetry violation and helps explain the search for the hypothetical axion particle, which may be a component of cosmic dark matter. Violations of CP (charge-parity) symmetry test the Standard Model of particle physics and help explain the excess of matter over antimatter in the universe. www.openquestions.com /oq-ph006.htm

Search for EDM in atoms, molecules and the neutron. CP and T Violation in atomic physics. The role of CP symmetry in the theory of strong interactions is also not well understood. Although the CP violation is explained naturally by the CKM matrix, it is not possible at present to check the self-consistency of this explanation. In a general field theory, CP violation is caused by the presence of a complex phase between different fundamental fields. www.phys.washington.edu /users/wcgriff/romalis/EDM

Charge, Parity, and Time Reversal (CPT) Symmetry Until 1964 it was thought that the combination CP was a valid symmetry of the Universe. Changing both C and P preserves the symmetry and we call this CP symmetry. The separate violations of P symmetry and C symmetry cancel to preserve CP symmetry. www.lbl.gov /abc/wallchart/chapters/05/2.html

CERN Courier - How CP violation came to B - IOP Publishing - article In CP (charge/parity) symmetry, the physics of left-handed particles is the same as that of right-handed antiparticles - a natural enough assumption after physicists had been shocked in 1956 to discover that nuclear beta decay is spectacularly left-right asymmetric (P-violating). However, in 1964 new experiments found that CP symmetry is also flawed. The quark transitions responsible for CP violation are conventionally described by a 3 x 3 matrix - the Cabibbo/Kobayashi/Maskawa (CKM) matrix - the rows and columns of which correspond to the six types of quark. cerncourier.com /main/article/41/3/2

Appendix 2: The Discovery of CP Violation: A Persuasive Experiment: A Supplement to Experiment in Physics The experimenters were quite aware of the relevance of their experiment to the question of CP violation, but they did not expect to observe it. The discovery of CP violation called for a theoretical explanation, a call that is still unanswered. In the latter at least ten alternatives were proposed, and although CP violation was accepted rather quickly, the alternatives were tested. plato.stanford.edu /entries/physics-experiment/app2.html

CPT Theorem CP is the result of carrying out the charge conjugation operation on the mirror image of an object. A form of symmetry is restored through the combination of the two operations of space reversal and charge conjugation. If the symmetry between matter and antimatter were perfect, the universe would be composed equally of matter and antimatter, which would interact and annihilate each other, releasing energy. sist.fnal.gov /archive/96-topics/papers/Halton_Peters/Halton_Peters,_KTeV.htm

Physics 3030 Class Notes #10 2/15/00 If processes that don't have parity symmetry also don't have charge conjugation symmetry they could still have the combined CP symmetry: For example, if parity switches left to right and charge conservation switches a neutrino to an antineutrino then CP on a (lefthanded as they all are) neutrino gives you a righthanded antineutrino- which exists. In 1964, Jim Cronin, Val Fitch, JH Christenson, and R. Turlay found that "CP" symmetry is violated in Kaon decays. CPT is required to be a perfect symmetry of nature for any quantum field theory www.physics.usu.edu /marshall/3030/notes10.htm

BBC - h2g2 - Symmetry and CP Violation As belief in symmetry was strong, particle physicists hoped that the combination of charge conjugation and parity (CP) would be an invariant symmetry - that the antimatter world would look like the 3D mirror image of the matter world. Finally, although it is now clear that the laws of physics are not invariant under C, P, or CP, scientists are still optimistic that the ultimate discrete symmetry CPT is not broken. Rotational symmetry is an example of a space-time symmetry; another is a translation through space, such as moving a coordinate system two metres to the left, or a translation in time, such as putting the clock forward one hour. www.bbc.co.uk /dna/h2g2/A599844

Physics Today Online - Books In the Standard Model of particle physics, CP symmetry is violated only in the quark-mixing matrix of the weak interactions. We are entering a golden age in the experimental study of charge conjugation­parity (CP) symmetry. CP violation in the B system will be probed in much more detail at dedicated electron­positron "B Factories" newly in operation at three laboratories in the United States and Japan. www.aip.org /pt/vol-53/iss-8/p50.html

Citebase - Domain wall fermion and CP symmetry breaking A modified form of lattice CP transformation motivated by the domain wall fermion, which keeps the chiral action in terms of the Ginsparg-Wilson fermion invariant, is analyzed in detail; this provides an alternative way to understand the breaking of CP symmetry at least in the topologically trivial sector. The CP symmetry is a fundamental discrete symmetry in chiral gauge theory. Open questions are touched also on perturbation theory, locality, Gribov copies, CP symmetry in chiral gauge theories and cut-off effects. citebase.eprints.org /cgi-bin/citations?id=oai%3AarXiv%2Eorg%3Ahep%2Dlat%2F0210013

Theory: Charge Conjugation Invariance This CP invariance violation was observed in K decays. The observed CP violation in K decay then leads to predicted relationships between a number of CP violating effects in B meson decays. For some time after the discovery of the left-handedness of neutrinos, it was thought that CP is an exact invariance of weak processes. www2.slac.stanford.edu /vvc/theory/chargeconjugation.html

A violation of CP symmetry in B meson decays Another fascinating aspect is that CP violation is one of the three necessary conditions to achieve a mechanism that can generate the global asymmetry in the Universe between matter and antimatter, starting with symmetric initial conditions at the time of the Big Bang. Therefore, the CP symmetry, which transforms a left-handed neutrino into a right-handed anti-neutrino, is a good symmetry of the weak interactions. At the time of the discovery of CP violation, in 1964, particle physicists generally accepted the assumption that CP is an exact symmetry of weak interactions. www.europhysicsnews.com /full/15/article4/article4.html

Hyperon Much of the research is done to test for CP violation by means of the 'HyperCP' experiments, which seek to measure the differences in the time for the decay of hyperons and their anti-matter counterparts, anti-hyperons. Today, most research is conducted at the Fermi National Accelerator Laboratory in Batavia, Illinois using particle accelerators. www.toshare.info /en/Hyperon.htm

Physics at Minnesota: Yuichi Kubota The violation of the symmetry of nature CP (particle world vs. antiparticle world and space inversion together) is a necessary ingredient in the scenario of the cosmic evolution from the Big Bang, and yet its source is not understood at all. CP symmetry breaking - necessary ingredient of cosmic evolution. Currently, CP violation is observed in the heavy quark decays, and explained by the way quarks are "mixed." But this does not give enough CP violation. www.physics.umn.edu /directory/yk.html?printer=yes&

Citebase - Of CP and other Gauge Symmetries in String Theory The possibility of spontaneous breaking of CP symmetry by the expectation values of orbifold moduli is investigated with particular reference to CP violating phases in soft supersymmetry breaking terms. We suggest here that CP is a discrete {\it gauge} symmetry, and is therefore not violated by quantum gravity. Authors: Dine, M. Leigh, R. MacIntire, D. We argue that \CP is a gauge symmetry in string theory. citebase.eprints.org /cgi-bin/citations?archiveID=oai:arXiv.org:hep-th/9205011

CERN confirms direct CP violation (June 1999) - News - PhysicsWeb If CP symmetry is conserved, the so-called short-lived neutral kaon, K-short, can decay into two pions, while the long-lived version, K-long, cannot. In 1964 Andrei Sakharov showed that CP violation was needed to explain why the universe was made of matter rather than anti-matter, even though equal amounts of both should have been created in the big bang. The NA48 experiment at CERN has reported a value for direct CP violation - one of the reasons for the dominance of matter over anti-matter in the universe - in agreement with the value reported by the KTeV experiment at Fermilab in February. physicsweb.org /article/news/3/6/13/1

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