Transverse energy–energy correlations of jets in the electron–proton deep inelastic scattering at HERA

Journal Article · Mon Nov 30 00:00:00 EST 2020 · European Physical Journal. C, Particles and Fields

DOI:https://doi.org/10.1140/epjc/s10052-020-08614-3· OSTI ID:1851477

Ali, Ahmed ^[1]; Li, Gang ^[2]; Wang, Wei ^[3]; Xing, Zhi-Peng ^[3]

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1. Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany)
2. Univ. of Massachusetts, Amherst, MA (United States)
3. Shanghai Jiao Tong Univ. (China)

We study the event shape variables, transverse energy–energy correlation TEEC (cosφ) and its asymmetry ATEEC (cosφ) in deep inelastic scattering (DIS) at the electron–proton collider HERA, where φ is the angle between two jets defined using a transverse-momentum (k_T) jet algorithm. At HERA, jets are defined in the Breit frame, and the leading nontrivial transverse energy–energy correlations arise from the 3-jet configurations. With the help of the NLOJET++, these functions are calculated in the leading order (LO) and the next-to-leading order (NLO) approximations in QCD at the electron–proton center-of-mass energy $$\sqrt{s}$$ = 314 GeV. We restrict the angular region to -0.8 ≤ cosφ ≤ 0.8, as the forward- and backward-angular regions require resummed logarithmic corrections, which we have neglected in this work. Following experimental jet-analysis at HERA, we restrict the DIS-variables x, y = Q²/(xs), where Q² = -q² is the negative of the momentum transfer squared q², to 0 ≤ x ≤ 1, 0.2 ≤ y ≤ 0.6, and the pseudo-rapidity variable in the laboratory frame (η^lab) to the range -1 ≤ η^lab ≤ 2.5. The TEEC and ATEEC functions are worked out for two ranges in Q², defined by 5.5GeV² ≤ Q² ≤ 80GeV², called the low-Q²-range, and 150GeV² ≤ Q² ≤ 1000GeV², called the high-Q²-range. We show the sensitivity of these functions on the parton distribution functions (PDFs), the factorization (μ_F) and renormalization (μ_R) scales, and on α_s(M$$^2_Z$$). Of these the correlations are stable against varying the scale μ_F and the PDFs, but they do depend on μ_R. For the choice of the scale μ_R=$$\sqrt{\langle ET \rangle^2+Q^2}$$, advocated in earlier jet analysis at HERA, the shape variables TEEC and ATEEC are found perturbatively robust. These studies are useful in the analysis of the HERA data, including the determination of α_s(M$$^2_Z$$) from the shape variables.

• Research Organization: Univ. of Massachusetts, Amherst, MA (United States)
• Sponsoring Organization: MOE key Laboratory for Particle Physics, Astrophysics and Cosmology; Natural Science Foundation of China; Natural Science Foundation of Shanghai; USDOE Office of Science (SC)
• Grant/Contract Number: SC0011095
• OSTI ID: 1851477
• Alternate ID(s): OSTI ID: 23006100
• Journal Information: European Physical Journal. C, Particles and Fields, Journal Name: European Physical Journal. C, Particles and Fields Journal Issue: 12 Vol. 80; ISSN 1434-6044
• Publisher: Springer
• Country of Publication: United States
• Language: English

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