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Measurements of Indirect CP Asymmetries in D-0 -> K-K+ and D-0 -> pi(-)pi(+) Decays

Abstract

A study of indirect CP violation in D-0 mesons through the determination of the parameter A(Gamma) is presented using a data sample of pp collisions, corresponding to an integrated luminosity of 1.0 fb(-1), collected with the LHCb detector and recorded at the center-of-mass energy of 7 TeV at the LHC. The parameter A(Gamma) is the asymmetry of the effective lifetimes measured in decays of D-0 and (D) over bar (0) mesons to the CP eigenstates K-K+ and pi(-)pi(+). Fits to the data sample yield A(Gamma)(KK) = (-0.35 +/- 0.62 +/- 0.12) x 10(-3) and A(Gamma)(pi pi) = (0.33 +/- 1.06 +/- 0.14) x 10(-3), where the first uncertainties are statistical and the second systematic. The results represent the world's best measurements of these quantities. They show no difference in A(Gamma) between the two final states and no indication of CP violation.

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Abstract

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Related concepts (22)

CP violation

In particle physics, CP violation is a violation of CP-symmetry (or charge conjugation parity symmetry): the combination of C-symmetry (charge 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). 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.

Kaon

In 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.

LHCb experiment

The 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.

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