Abstract
In the paper we present results for final state emissions of lepton pairs in decays of heavy intermediate states such as Z boson. Short presentations of PHOTOS and SANC algorithms and physics assumptions are given. Numerical distributions of relevance for LHC observables are shown. They are used in discussions of systematic errors in the predictions of pair emissions as implemented in the two programs. Suggestions for the future works are given. Present results confirm, that for the precision of 0.3% level, in simulation of final state the pair emissions can be avoided. For the precision of 0.1-0.2%, the results obtained with the presented programs should be enough. To cross precision tag of 0.1%, the further work is however required.
Highlights
With the increasing precision of measurements, more detailed theoretical calculations are needed for interpretation of results in the language of physics parameters such as masses or couplings of Z and W bosons
We have introduced the following option into PHOTOS; instead of generating in 50% of cases, pair emission before algorithm for photon emission is involved, we have always generated pairs as the last step
Standard tests with the help of MC-TESTER demonstrate about 4% increase in the number of final states consisting of configurations with the added pair and at least one real photon of energy above 1 GeV
Summary
With the increasing precision of measurements, more detailed theoretical calculations are needed for interpretation of results in the language of physics parameters such as masses or couplings of Z and W bosons. We concentrate on effects and uncertainties related to the emission of real lepton pair in association with the Drell–Yan processes. Our main goal is to study the effect of light pair emission f fin the neutral current Drell–Yan process qq → γ/Z → + −(f f) for pp collisions at the LHC. We consider the cases = e, μ and f = e, μ This effect should be included starting from the second order of QED, i.e. from the O(α2). We will show the program features important for effect of pair emissions, respectively, in Sections 2 and 3. The numerical comparison of the results from the two programs and benchmark semi-analytical calculations is presented. Extensive Appendix collects the result of our new semi-analytical calculations for pair emissions which is used to obtain numerical results necessary to understand origin of PHOTOS–SANC differences
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
