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arXiv · 2606.17184

Measurement of dijet transverse momentum imbalance and azimuthal acoplanarity in $p$+$p$ collisions at $\sqrt{s} = 200$ GeV with the sPHENIX detector

Abstract

This Letter reports on measurements of dijet transverse momentum ($p_\mathrm{T}$) imbalance and azimuthal acoplanarity in proton-proton collisions at $\sqrt{s} = 200$~GeV, using data recorded by the sPHENIX detector at the Relativistic Heavy Ion Collider corresponding to an integrated luminosity of $41$~pb$^{-1}$. Jets are reconstructed using the anti-$k_t$ algorithm with radius parameters $R = 0.3$ to $0.8$ from electromagnetic and hadronic calorimeter energy deposits. The jet $p_\mathrm{T}$ resolution is determined directly in data using two independent methods. The dijet $p_\mathrm{T}$ imbalance is characterized by the ratio $x_\mathrm{J} = p_\mathrm{T,2}/p_\mathrm{T,1}$ where $p_\mathrm{T,1(2)}$ is the highest (second-highest) jet $p_\mathrm{T}$ in the event. The dijet azimuthal acoplanarity $\Delta\phi = |\phi_1 - \phi_2|$ is also reported. Results are reported for different $p_\mathrm{T,1}$ selections and jet radius parameters, normalized per dijet pair, and compared to the results of \textsc{Pythia} and \textsc{Herwig} Monte Carlo event generators. These measurements provide a stringent quantitative test of the modeling of QCD parton shower and hadronization dynamics, place important constraints on event-generator descriptions at RHIC energies, and establish a comprehensive proton-proton baseline for forthcoming measurements of jet modification in heavy ion collisions.

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BibTeXRIS

sPHENIX Collaboration, M. I. Abdulhamid, U. Acharya, E. R. Adams, G. Adawi, I. Ahmed, C. A. Aidala, Y. Akiba, M. Alfred, S. Ali, A. Alsayegh, S. Altaf, H. Amedi, D. M. Anderson, V. V. Andrieux, A. Angerami, N. Applegate, M. U. Ashraf, H. Aso, S. Aune, B. Azmoun, V. R. Bailey, D. Baranyai, S. Bathe, A. Bazilevsky, S. Bela, R. Belmont, J. Bennett, J. C. Bernauer, J. Bertaux, R. Bi, A. Bonenfant, S. Boose, C. Borchers, H. Bossi, R. Botsford, R. Boucher, A. Brahma, J. W. Bryan, D. Cacace, I. Cali, M. Chamizo-Llatas, S. B. Chauhan, A. Chen, D. Chen, J. Chen, K. Chen, K. Y. Chen, K. Y. Cheng, C. -Y. Chi, M. Chiu, J. Clement, E. W. Cline, M. Connors, E. Cook, R. Corliss, Y. Corrales Morales, E. Croft, N. d'Hose, A. Dabas, D. Dacosta, M. Daradkeh, S. J. Das, A. P. Dash, G. David, C. T. Dean, K. Dehmelt, X. Dong, A. Drees, J. Driebeek, J. M. Durham, A. Enokizono, H. Enyo, J. Escobar Cepero, R. Esha, B. Fadem, R. Feder, K. Finnelli, D. Firak, D. S. Fitzgerald, L. V. Flores-Sanchez, A. Francisco, J. Frantz, A. Frawley, K. Fujiki, M. Fujiwara, B. Garcia, P. Garg, G. Garmire, E. Gentry, Y. Go, C. Goblin, I. Goel, W. Goodman, Y. Goto, A. Grabas, O. Grachov, J. Granato, N. Grau, S. V. Greene. 2026-06-15. Measurement of dijet transverse momentum imbalance and azimuthal acoplanarity in $p$+$p$ collisions at $\sqrt{s} = 200$ GeV with the sPHENIX detector. https://arxiv.org/abs/2606.17184

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