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Evidence for CP violation in time-integrated D0→h(-)h(+) decay rates.
R Aaij1, C Abellan Beteta, B Adeva
1Nikhef National Institute for Subatomic Physics, Amsterdam, The Netherlands.
Physical Review Letters
|May 1, 2012
Summary
Researchers searched for CP violation in charm meson decays D(0) to K(-)K(+) and π(-)π(+). The measured difference in CP asymmetry suggests a deviation from CP conservation, observed with 3.5 standard deviations significance.
Area of Science:
- Particle Physics
- High-Energy Physics
- Quantum Mechanics
Background:
- CP symmetry is a fundamental principle in particle physics, stating that physical laws remain the same under charge conjugation and parity transformation.
- Investigating CP violation in the charm sector is crucial for understanding matter-antimatter asymmetry in the universe.
Purpose of the Study:
- To search for direct CP violation in time-integrated D(0) to K(-)K(+) and D(0) to π(-)π(+) decays.
- To measure the difference in CP asymmetry, ΔA(CP), between these two decay modes.
Main Methods:
- Utilized 0.62 fb⁻¹ of data collected by the LHCb experiment in 2011.
- Determined charm meson flavor using the charge of the slow pion in D* decays.
- Analyzed D(0)→h(-)h(+) decays, where h represents either a K or π meson.
Main Results:
- The difference in CP asymmetry, ΔA(CP)≡A(CP)(K(-)K(+))-A(CP)(π(-)π(+)), was measured to be [-0.82±0.21(stat)±0.11(syst)]%.
- This result shows a deviation from the hypothesis of CP conservation at the level of 3.5 standard deviations.
Conclusions:
- The observed difference in CP asymmetry provides evidence for CP violation in the studied charm decays.
- This finding may offer new insights into the sources of CP violation beyond the Standard Model of particle physics.
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