Transverse Energy-Energy Correlations of jets in the electron-proton Deep Inelastic Scattering at HERA

Ali, Ahmed; Xing, Zhi-Peng; Li, Gang; Wang, Wei

Preprint

PUBDB-2020-03045

Transverse Energy-Energy Correlations of jets in the electron-proton Deep Inelastic Scattering at HERA

Ali, A.Extern*DESY* ; Li, G. ; Wang, W.Extern* ; Xing, Z.-P.

2020

1-18 (2020) [10.3204/PUBDB-2020-03045]

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Please use a persistent id in citations: doi:10.3204/PUBDB-2020-03045

Report No.: ACFI-T20-09; DESY-20-129; arXiv:2008.00271

Abstract: We study the event shape variables, transverse energy energy correlation TEEC $(\cos \phi)$ and its asymmetry ATEEC $(\cos \phi)$ in deep inelastic scattering (DIS) at the electron-proton collider HERA, where $\phi$ 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 $-0.8 \leq \cos \phi \leq 0.8$, 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 $x$, $y=Q^2/(x s)$, where $Q^2=-q^2$ is the negative of the momentum transfer squared $q^2$, to $0 \leq x \leq 1$, $0.2 \leq y \leq 0.6$, and the pseudo-rapidity variable in the laboratory frame $(\eta^{\rm {lab}})$ to the range $-1 \leq \eta^{\rm {lab}} \leq 2.5$. The TEEC and ATEEC functions are worked out for two ranges in $Q^2$, defined by $5.5~{\rm GeV}^2 \leq Q^2 \leq 80~{\rm GeV}^2$, called the low-$Q^2$-range, and $150~{\rm GeV}^2 \leq Q^2 \leq 1000~{\rm GeV}^2$, called the high-$Q^2$-range. We show the sensitivity of these functions on the parton distribution functions (PDFs), the factorization $(\mu_F)$ and renormalization $(\mu_R)$ scales, and on $\alpha_s(M_Z)$. Of these the correlations are stable against varying the scale $\mu_F$ and the PDFs, but they do depend on $\mu_R$. These studies are useful in the analysis of the HERA data, including the determination of $\alpha_s(M_Z)$ from the shape variables.

Keyword(s): parton: distribution function ; jet: correlation ; electron p: deep inelastic scattering ; track data analysis: jet ; higher-order: 0 ; higher-order: 1 ; DESY HERA Stor ; transverse energy ; quantum chromodynamics ; event shape analysis ; transverse momentum ; momentum transfer ; renormalization ; factorization ; Breit frame ; sensitivity ; transverse ; stability ; asymmetry