Prospects for measuring quark polarization and spin correlations in $b\bar{b}$ and $c\bar{c}$ samples at the LHC

TL;DR

This paper explores the potential to measure quark polarization and spin correlations in bottom and charm quark pairs at the LHC, proposing analysis strategies and predicting measurable effects with current and future datasets.

Contribution

It introduces new analysis strategies for measuring quark polarization and spin correlations in $b\bar{b}$ and $c\bar{c}$ samples at the LHC, including theoretical predictions and feasibility assessments.

Findings

Polarization measurements for $b$ and $c$ quarks are feasible with current datasets.

Spin correlation measurements for $b\bar{b}$ are possible using CMS Run 2 data.

Higher luminosity will enable spin correlation measurements for $c\bar{c}$.

Abstract

Polarization and spin correlations have been explored very little for quarks other than the top. Utilizing the partial preservation of the quark's spin information in baryons in the jet produced by the quark, we examine possible analysis strategies for ATLAS and CMS to measure the quark polarization and spin correlations in $pp\to q\bar{q}$ processes. We find polarization measurements for the $b$ and $c$ quarks to be feasible, even with the currently available datasets. Spin correlation measurements for $b\bar{b}$ are possible using the CMS Run 2 parked data, while such measurements for $c\bar{c}$ will become possible with higher integrated luminosity. We also provide leading-order QCD predictions for the polarization and spin correlations expected in the $b\bar{b}$ and $c\bar{c}$ samples with the relevant cuts. These proposed analyses can provide new information on the polarization transfer from quarks to baryons, measure entanglement and Bell nonlocality in the $b\bar b$ final state, and might even be sensitive to physics beyond the Standard Model.