Violation Of CP Symmetry Research Articles

Particle electric dipole moments

Measurements of particle electric dipole moments (EDMs) continue to put powerful constraints on theories of T-symmetry and CP-symmetry violation, which form currently one of the most prominent fields in particle physics. EDM measurements have been concentrated on neutral systems such as the neutron and atoms and molecules. These measurements allow one to deduce, in turn, the electric dipole moments of the fundamental fermions, that is, the lighter leptons and quarks and also those of some heavy nuclei.

Italy's KLOE Sets Sights on CP Violation

PARTICLE PHYSICSNAPLES, ITALY-- The titans of the particle physics world, the CERN laboratory near Geneva and Fermilab near Chicago, are racing to confirm that matter and antimatter are not always completely equivalent--in technical parlance, they are searching for violation of CP symmetry. But at Frascati, south of Rome, a more modest outfit hopes to rob them of that prize. Last week, this upstart machine, called KLOE, recorded its first real data. KLOE is a new detector purpose-built to look for CP violation in particles produced by DAFNE, Italy's new electron-positron collider at the National Institute for Nuclear Physics.

SLAC's Asymmetric B Factory Will Study CP Violation

Showing off an acceleration section of PEP-II, the brand new “asymmetic B factory” at the Stanford Linear Accelerator Center (SLAC), are Jonathan Dorfan (rear), the project's director, and Pier Oddone (Lawrence Berkeley National Laboratory), who first suggested ten years ago that panicle physicists seeking to find and study CP symmetry violation in B meson systems ought to build such asymmetric electron-positron colliders. B mesons, first observed in the early 1980s, carry the heavy b (bottom) quark.

Front end electronics for high rate microstrip gaseous chamber readout

HERA-B is an experiment at the ep storage ring HERA at DESY designed to study the violation of CP symmetry in the B system. Groups from the Universities of Heidelberg, Siegen and Zurich develop the inner tracker system of the detector consisting of microstrip gaseous detectors and electronics for about 150 000 channels. For the readout system a completely new development in VLSI technology is necessary, because of the large number of channels and the high occupancy of up to 10% at beam crossing rates of 10 MHz. A simulation program has been developed including the basic detector response and possible filter strategies for optimisation of efficiency (>98%) and for minimisation of uncorrelated trigger signals. Chips, existing and in design phase, are analysed and compared with simulations and measurements. A concept for the complete readout system including first level trigger extraction and transmission of high data rates is presented.

Construction Proposals Take Aim at Top and Bottom Quarks

Cornell and Stanford are competing to build a B-meson “factory,” and Fermilab wants to build a new injector ring for its Tevatron Collider. These are the two principal new construction initiatives proposed by the US highenergy-physics community for completion by the middle of this decade. They are intended to address the two remaining “dangling participles” of the spectacularly successful standard model of the elementary particles: Understanding the violation of CP symmetry would seem to require a new source of B mesons much more profuse than the existing electronpositron rings; and determining the properties of the (still missing) top quark in adequate detail appears to necessitate an order of magnitude increase in the luminosity of the Tevatron proton-antiproton collider.

A Flaw in a Universal Mirror

The existence of the universe as we know it comes from a flaw in a symmetry exhibited by a universal mirror called the CP mirror; a symmetry that says the outcomes of some events in nature should remain the same on changing matter to antimatter (C) and viewing the result in a mirror (P). New theoretical ideas developed in the past few years have driven a new generation of experiments that promise to throw new light on the flaw. These experiments are conceived to examine the character of the force responsible for CP symmetry and to determine if the very small asymmetry follows from a weak (milliweak) force acting twice or a very weak (superweak) force acting once in particle interactions. In 1964, James Cronin and Val Fitch showed that small violations of CP symmetry occurred for neutral K mesons. Clearly the set of neutral K mesons forms a system that provides for particularly sensitive tests of CP invariance violation. Both milliweak and superweak concepts are not so much theories as they are sets of theories. Results from recent experiments at Brookhaven National Laboratory and Fermi Laboratory have served to exclude some but not all interesting milliweak models of CPmore » invariance violation. 6 figs.« less

On the possible origin ofCP violation in neutral-kaon decay

The author's research program on elementary-particle physics from general relativity is applied to explain the violation ofCP symmetry in KL0 decay. Because the theory implies that all reflection symmetries are rejected in the irreducible (two-component spinor) form of the matter field equations, it follows that all bosons, including the pions and kaons, must be composites of spinor components. It is concluded from the analysis that the generalized interactions must contain odd as well as even terms under (all) reflections, and one of these is responsible for the 3π decay and the other is responsible for the 2π decay. But the pions themselves are composites of protons and antiprotons and the π0 of the 3π decay is the antisymmetric state of the composite (p+p−) that binds with two other pseudoscalar composites in the original KL0. In the 2π decay, the (p+p−) pair is still present, but in terms of a symmetric composite, rather than in terms of the π0 (antisymmetric) form. The latter (symmetric) state of the particle pair was derived in earlier studies from an exact solution of the nonlinear coupled spinor field equations for the particle-antiparticle pair in which it was found to correspond to an «unobserved» state—thus accounting for the disappearance of the π0 component, looking like a 2π decay. The ratio of theCP-violating part to theCP-conserving part of the decay rate of the long-lived neutral kaon is calculated within the context of this field theory in a semi-phenomenological way, and found to yield the same order of magnitude, ∼10−3, as the ratio that was observed by Cronin and Fitch.

CP symmetry violation

Sixteen years before the discovery of charge-conjugation–parity nonconservation in the decay of K mesons, a very fine high-school physics teacher got me interested in physics. I'm not sure that I wouldn't have been interested in it anyway, but nevertheless he was a remarkable gentleman in a high school in Dallas, Texas. I think high-school physics teachers continue to play a crucial role today, so I want to make one or two remarks about physics teaching before I describe the fascinating behavior of K mesons and discuss some of the historical and human aspects of the research that Val Fitch and I did on their decay.

CP Symmetry Violation: The Search for Its Origin

The author presents a brief review of the progress which has been made in understanding CP violation since its discovery. Experiments in Kaon systems and the measurement of parameters associated with long-lived neutral kaon decay are described. Theoretical ideas about CP violation are briefly considered. Forty eight references are given.

CP and CPT symmetry violations, entropy and the expanding universe

The conjecture linking together statistical and cosmological time arrows implies interpreting the contracting phase in an oscillating cosmological model as a time-inverted expansion. The Fitch-Cronin effect now requires a redefinition of which is matter and which is antimatter in this time-inverted picture. However, ifCPT is also broken, then theT-violating effects yield a different set of laws altogether for such reactions.