Abstract
We discuss the sensitivity of theoretical predictions of observables used in searches for new physics to parton distributions (PDFs) at large momentum fraction x. Specifically, we consider the neutral-current Drell–Yan production of gauge bosons with invariant masses in the TeV range, for which the forward–backward asymmetry of charged leptons from the decay of the gauge boson in its rest frame is a traditional probe of new physics. We show that the qualitative behaviour of the asymmetry depends strongly on the assumptions made in determining the underlying PDFs. We discuss and compare the large-x behaviour of various different PDF sets, and find that they differ significantly. Consequently, the shape of the asymmetry observed at lower dilepton invariant masses, where all PDF sets are in reasonable agreement because of the presence of experimental constraints, is not necessarily reproduced at large masses where the PDFs are mostly unconstrained by data. It follows that the shape of the asymmetry at high masses may depend on assumptions made in the PDF parametrization, and thus deviations from the traditionally expected behaviour cannot be taken as a reliable indication of new physics. We demonstrate that forward–backward asymmetry measurements could help in constraining PDFs at large x and discuss the accuracy that would be required to disentangle the effects of new physics from uncertainties in the PDFs in this region.
| Original language | English |
|---|---|
| Article number | 1160 |
| Pages (from-to) | 1-25 |
| Number of pages | 25 |
| Journal | European Physical Journal C |
| Volume | 82 |
| Issue number | 12 |
| Early online date | 22 Dec 2022 |
| DOIs | |
| Publication status | Published - Dec 2022 |
Bibliographical note
Funding Information:We are grateful to Dimitri Bourilkov, Alexander Grohsjean, Meng Lu, and Jan Schulte for raising with us the issue of the PDF dependence of at high invariant masses and for the subsequent discussions. A. C., S. F., and F. H. are supported by the European Research Council under the European Union’s Horizon 2020 research and innovation Programme (grant agreement n.740006). R. D. B. is supported by the U.K. Science and Technology Facility Council (STFC) grant ST/P000630/1. E. R. N. is supported by the Italian Ministry of University and Research (MUR) through the “Rita Levi-Montalcini” Program. J. R. is partially supported by NWO (Dutch Research Council). C. S. is supported by the German Research Foundation (DFG) under reference number DE 623/6-2.
Publisher Copyright:
© 2022, The Author(s).
Funding
We are grateful to Dimitri Bourilkov, Alexander Grohsjean, Meng Lu, and Jan Schulte for raising with us the issue of the PDF dependence of at high invariant masses and for the subsequent discussions. A. C., S. F., and F. H. are supported by the European Research Council under the European Union’s Horizon 2020 research and innovation Programme (grant agreement n.740006). R. D. B. is supported by the U.K. Science and Technology Facility Council (STFC) grant ST/P000630/1. E. R. N. is supported by the Italian Ministry of University and Research (MUR) through the “Rita Levi-Montalcini” Program. J. R. is partially supported by NWO (Dutch Research Council). C. S. is supported by the German Research Foundation (DFG) under reference number DE 623/6-2.
| Funders | Funder number |
|---|---|
| Nederlandse Organisatie voor Wetenschappelijk Onderzoek | |
| Ministero dell’Istruzione, dell’Università e della Ricerca | |
| European Research Council | |
| UK Research and Innovation | |
| Horizon 2020 Framework Programme | 740006 |
| Deutsche Forschungsgemeinschaft | DE 623/6-2 |
| Science and Technology Facilities Council | ST/P000630/1 |