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ATLAS Collaboration(Aad, G. et al), Aikot, A., Amos, K. R., Bouchhar, N., Cabrera Urban, S., Cantero, J., et al. (2026). Characterization of nuclear breakup as a function of hard-scattering kinematics using dijets measured by ATLAS in p plus Pb collisions. Phys. Lett. B, 877, 140440–18pp.
Abstract: This Letter analyzes the sensitivity of event geometry estimators to the initial-state kinematics of hard scattering in proton-lead collisions. This analysis uses dijets as a proxy for the parton-parton scattering configuration, correlating it with event geometry estimators, namely the energy deposited in the Zero-Degree Calorimeter and the transverse energy recorded in the Forward Calorimeter in the Pb-going direction. The analysis uses data recorded by the ATLAS detector at the Large Hadron Collider with a nucleon-nucleon center-of-mass energy of 8.16 TeV, corresponding to an integrated luminosity of 56 nb(-1). The jets are measured within the pseudorapidity interval -2.8 < eta < 4.5, where positive eta values correspond to the direction of the proton beam. Results are presented as a function of the Bjorken-x of the parton originating from the proton, x(p). Both event geometry estimators are found to be dependent on x(p), with the energy deposited in the Zero-Degree Calorimeter about six times less sensitive to x(p) compared with the transverse energy deposited in the Forward Calorimeter.
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ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Escobar, C., et al. (2011). Search for quark contact interactions in dijet angular distributions in pp collisions at sqrt(s)=7 TeV measured with the ATLAS detector. Phys. Lett. B, 694(4-5), 327–345.
Abstract: Dijet angular distributions from the first LHC pp collisions at center-of-mass energy root s = 7 TeV have been measured with the ATLAS detector. The dataset used for this analysis represents an integrated luminosity of 3.1 pb(-1). Dijet chi distributions and centrality ratios have been measured up to dijet masses of 2.8 TeV, and found to be in good agreement with Standard Model predictions. Analysis of the chi distributions excludes quark contact interactions with a compositeness scale Lambda below 3.4 TeV, at 95% confidence level, significantly exceeding previous limits.
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