Descripción del proyecto
Descubrimientos sobre el Big Bang: los quarks encantados
Las partículas de materia y antimateria tienen la misma masa, pero otras propiedades, como su carga eléctrica, son opuestas. Siempre se generan en parejas y se destruyen unas a otras cuando entran en contacto, por lo que el predominio observado de la materia sobre la antimateria —asimetría materia-antimateria conocida como violación de la simetría carga-paridad (CP)— sugiere la existencia de un eslabón perdido. Las teorías que predicen la cantidad de violación de la CP en el universo y la violación de la CP observada en experimentos no dan cuenta de esta diferencia. En 2019, se observó por primera vez una violación de la CP en partículas que contenían quarks encantados. El proyecto CharmAsymmetries, financiado con fondos europeos, se basa en este hallazgo histórico a partir de nuevos análisis de los datos, a la búsqueda de procesos de violación de la CP en otras desintegraciones de mesones encantados que todavía no han sido observadas.
Objetivo
The study of difference between matter and antimatter (CP violation) is one of the most exciting fields at the frontier of fundamental physics research. It is driven by the question of what happened to the antimatter after the Big Bang. The mesons, particles that contain both matter and antimatter quarks are ideal laboratories for the discovery of CP violation. This proposal aims at looking for CP violation in decays of mesons containing one charm (or anti-)quark, the only type of mesons where CP violation has not yet been observed.
One of the objectives is to carry out a measurement of the matter-antimatter mixing and CP violation parameters in the most sensitive charm decay mode (D0->Kspipi) using the unprecedented charm data sample collected by the LHCb experiment at CERN. To achieve maximal precision of both measurements, external input from the unique Chinese flavour factory, BESIII, is crucial. Key attributes of the decays of the D meson, the strong phases and their variation across the phase space, require the use of quantum-entangled states that are accessible at BESIII. Usually, these quantities are measured in regions of the phase space, the definition of which is inspired by a model. Wrong definition of these regions would lead to dilution of the sensitivity of these measurements. We propose to measure these quantities at every point of the phase space to maximise the precision.
The second objective is to look for CP violation in the charm D0->(anti-)K*0KS decays with LHCb data ignoring time-dependent effects arising from matter-antimatter mixing. The three-body final state after an instant decay of the exited K*0 meson, K pi KS, will be studied using novel model-dependent and model independent methods, the former has been pioneered by the Manchester LHCb group, and the latter has not yet been tested. Currently, these decays have been highlighted by theorists as the most likely discovery channel for time-integrated CP violation in the charm system.
Ámbito científico
Programa(s)
Régimen de financiación
MSCA-IF-EF-ST - Standard EFCoordinador
M13 9PL Manchester
Reino Unido