Abstract
Resonance particles, such as the K*(892) meson, are reconstructed from the invariant mass (M i n v ) distribution of possible particle pairs. To extract the yield with the highest precision, the combinatorial background must be determined as precisely as possible. An event-mixed M i n v distribution is often used to describe the combinatorial background. However, this distribution will not contain the mini-jet-like structures present inside an event. This analysis introduces a new re-weighing scheme, where two M i n v distributions of like-sign particles in the same-event and in mixed-events are used to correct the mixed-event background estimate for the mini-jet-like structure. Using PYTHIA 8.2 generated proton-proton collisions at s NN = 5.02 TeV, it is shown that the new method can be used to more accurately describe the combinatorial background.
Highlights
Resonance particles, such as the K*(892) meson, are produced as intermediary states in high-energy hadronic collisions
As it is not possible to distinguish whether a single track has decayed from a resonance, the Minv has to be calculated for every possible track pair
The structure observed in the same-event distribution is due to the di-jet topology found in many p-p collisions
Summary
Resonance particles, such as the K*(892) meson, are produced as intermediary states in high-energy hadronic collisions. The resulting Minv signal distribution will contain a peak representing the yield of the resonance particle, on top of a combinatorial background. The event-mixed distribution contains track pairs that are completely disjoint in time, and are fully uncorrelated. The event-mixed distribution is used to describe the combinatorial background in the signal distribution This method is often preferred over using a like-sign background estimation, as the signal and background distribution will contain track pairs that have the same acceptance bias. This method is not able to completely describe the combinatorial background, which has been observed in K*(892) decays from A Large Ion Collider
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