https://doi.org/10.1140/epjc/s10052-020-08614-3
Regular Article - Theoretical Physics
Transverse energy–energy correlations of jets in the electron–proton deep inelastic scattering at HERA
1
Deutsches Elektronen-Synchrotron DESY, 22607, Hamburg, Germany
2
Amherst Center for Fundamental Interactions, Department of Physics, University of Massachusets Amherst, 01003, Amherst, MA, USA
3
INPAC, Shanghai Key Laboratory for Particle Physics and Cosmology, MOE Key Laboratory for Particle Astrophysics and Cosmology, School of Physics and Astronomy, Shanghai Jiao Tong University, 200240, Shanghai, China
Received:
6
August
2020
Accepted:
29
October
2020
Published online:
30
November
2020
We study the event shape variables, transverse energy–energy correlation TEEC 
and its asymmetry ATEEC in deep inelastic scattering (DIS) at the electron–proton collider HERA, where 
is the angle between two jets defined using a transverse-momentum 
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 
GeV. We restrict the angular region to 
, 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, 
, where 
is the negative of the momentum transfer squared 
, to 
, 
, and the pseudo-rapidity variable in the laboratory frame 
to the range 
. The TEEC and ATEEC functions are worked out for two ranges in 
, defined by 
, called the low--range, and 
, called the high--range. We show the sensitivity of these functions on the parton distribution functions (PDFs), the factorization 
and renormalization 
scales, and on 
. Of these the correlations are stable against varying the scale 
and the PDFs, but they do depend on 
. For the choice of the scale 
, 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 from the shape variables.
© The Author(s) 2020
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