Measuring polarization of light quarks at ATLAS and CMS

Abstract

Polarization of strange quarks is preserved to a high degree when they hadronize into Lambda baryons, as observed in Z decays at LEP. This opens up the possibility for ATLAS and CMS to use strange-quark polarization measurements as a characterization tool for new physics scenarios that produce such quarks. Measurements in ttbar samples would be useful for obtaining additional information about the polarization transfer from the strange quark to the Lambda baryon. Already with 100/fb in Run 2, ttbar samples in ATLAS and CMS become competitive in sensitivity with the Z samples of the LEP experiments. Moreover, while the LEP measurements were done inclusively over all quark flavors, which makes their interpretation dependent on various modeling assumptions, ttbar events at the LHC offer multiple handles for disentangling the different contributions experimentally. We also discuss the possibility of measuring polarizations of up and down quarks.

16 pages; v2: minor improvements, published version

References in corpus (14)

• Squark and gluino production cross sections in pp collisions at $\sqrt{s}$ = 13, 14, 33 and 100 TeV
• Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using $\sqrt{s}=8$ TeV proton--proton collision data
• Search for pair-produced third-generation squarks decaying via charm quarks or in compressed supersymmetric scenarios in $pp$ collisions at $\sqrt{s}=8$TeV with the ATLAS detector
• Measurement of the Lambda(b) cross section and the anti-Lambda(b) to Lambda(b) ratio with Lambda(b) to J/Psi Lambda decays in pp collisions at sqrt(s) = 7 TeV
• A study of the b-quark fragmentation function with the DELPHI detector at LEP I and an averaged distribution obtained at the Z Pole
• Top Quark Pair Production beyond NNLO
• NNNLO soft-gluon corrections for the top-antitop pair production cross section
• Measurement of the Longitudinal Spin Transfer to Lambda and Anti-Lambda Hyperons in Polarised Muon DIS
• Search for Scalar Charm Quark Pair Production in pp Collisions at $\sqrt{s}=8$ TeV with the ATLAS Detector
• Measurement of the parity-violating asymmetry parameter alpha_b and the helicity amplitudes for the decay Lambda_b->J/psi+Lambda with the ATLAS detector
• Longitudinal Spin Transfer to the $\Lambda$ Hyperon in Semi-Inclusive Deep-Inelastic Scattering
• Measurement of the top pair production cross-section in 8 TeV proton-proton collisions using kinematic information in the lepton+jets final state with ATLAS
• Measurement of the transverse polarization of $\Lambda$ and $\bar{\Lambda }$ hyperons produced in proton-proton collisions at $\sqrt{s}=7$ TeV using the ATLAS detector
• Factorization analysis for the fragmentation functions of hadrons containing a heavy quark

Cited by in corpus (5)

• Quantum state tomography, entanglement detection and Bell violation prospects in weak decays of massive particles
• Prospects for measuring quark polarization and spin correlations in $b\bar{b}$ and $c\bar{c}$ samples at the LHC
• Kinked tracks from ${\Sigma }^{+}$ baryons as a probe of light quark polarizations
• $O({\alpha }_s)$ perturbative and nonperturbative corrections to polarized semileptonic ${\Lambda }_b$ decay distributions
• Measuring quark polarizations at ATLAS and CMS