It is now possible to most accurately measure the lifetime of beautiful electrically neutral mesons.

Collaboration with ATLAS at the Large Hadron Collider (LHC) yields new high-precision measurements of the lifetime of electrically neutral beautiful (B0) mesons (hadrons consisting of a bottom antiquark and a down quark). Announced.

Beauty (B) A meson consists of two quarks, one of which is the bottom quark. Over the past few decades, physicists have studied B mesons for rare and precisely predicted phenomena to gain insights into interactions mediated by the weak force and the dynamics of heavy quark bound states. is completed. In this context, it is very important to accurately measure the lifetime of a B0 meson (the average time it takes to decay into other particles).

A new ATLAS study of B0 mesons investigated the particle’s decay into excited neutral kaons (K*0) and J/ψ mesons. The J/ψ meson then decays into a pair of muons, while the K*0 meson is studied through its decay into a charged pion and a charged kaon. The analysis is based on proton-proton collision data collected by the ATLAS detector during LHC Experiment 2 (2015-2018), which corresponds to an impressive dataset of 140 inverted femtobarns. (One inverted femtobahn is equivalent to approximately 100 trillion proton-proton collisions).

ATLAS researchers estimate the lifetime of the B0 meson to be 1.5053 picoseconds (1 picosecond (ps) is one trillionth (10-12) second), with a statistical uncertainty of 0.0012 ps, and a systematic uncertainty was measured to be 0.0035 ps. This result is the most accurate to date and is a significant improvement over previous measurements, including previous ATLAS results.

Achieving such accuracy required overcoming many experimental challenges, including minimizing systematic uncertainties, performing accurate modeling, and improving detector alignment.

In addition to measuring the B0 meson’s lifetime, the ATLAS team calculated the “width” of its decay. Width is a fundamental parameter for unstable particles with finite lifetime. The shorter the lifetime, the wider the attenuation width. This is a direct consequence of the Heisenberg uncertainty relation in quantum mechanics. The decay width of the B0 meson was measured to be 0.664 inverted picoseconds (ps-1), with a total uncertainty of 0.004 ps-1.

The researchers compared their results with previous measurements of the decay width of Bs0 mesons (composed of bottom quarks and strange quarks). They found that the attenuation width ratio was consistent with 1, reflecting a close value of the measured width. These results are consistent with the predictions of the heavy quark model and can be used to further refine these predictions.

The new ATLAS precision measurements will improve our understanding of weak force-mediated damping in the Standard Model and provide valuable data for future theory development.