LHC EFT WG meeting

Monday 9 Oct 2023, 15:00 → 16:30 Europe/Zurich

online

Robert Schoefbeck (Hephy Vienna)

To subscribe to the WG mailing list, click here. The starting time of 3 p.m. is exceptional.

lhc-eft-wg-2023-10-10.mp4

1 Probing new physics through entanglement in diboson production

Pair production of heavy vector bosons is a key process at colliders: it allows to
test our understanding of the Standard Model and to explore the existence of new physics through precision measurements of production rates and differential distributions. New physics effects can be subtle and often require observables specifically designed for their detection. In this study, we focus on quantum information observables that characterise the spin states of the final diboson system. We analyse concurrence bounds, purity, and Bell inequalities for a bipartite qutrit system representing two massive gauge bosons. Our findings show that quantum spin observables can serve as complementary probes for heavy new physics as parametrised by higher dimensional operators in the Standard Model effective field theory. In particular, we find that these observables offer increased sensitivity to
operators whose contributions do not interfere with the Standard Model amplitudes at the level of differential cross sections.

Speaker: Dr Eric Madge Pimentel (Weizmann Institute of Science)

2307.09675

talk.pdf

2 Hide and seek: how PDFs can conceal New Physics

The interpretation of LHC data, and the assessment of possible hints of new
physics, require the precise knowledge of the proton structure in terms of parton distribution functions (PDFs). We present a systematic methodology designed to determine whether and how global PDF fits might inadvertently ‘fit away’ signs of new physics in the high-energy tails of the distributions. We showcase a scenario for the High-Luminosity LHC, in which the PDFs may completely absorb such signs of new physics, thus biasing theoretical predictions and interpretations. We discuss strategies to single out the effects in this scenario, and disentangle the inconsistencies that stem from them. Our study brings to light the synergy between the high luminosity programme at the LHC and future lowenergy non-LHC measurements of large-x sea quark distributions. The analysis code used in this work is made public so that any users can test the robustness of the signal associated to a given BSM model against absorption by the PDFs.

Speaker: Luca Mantani (DAMTP, University of Cambridge)

2307.10370

LHC-EFT-WG-contamination.pdf

3 UFO models for neutral triple gauge couplings

The main goal of this talk is to present the universal feynrules output (UFO) model for neutral triple gauge couplings (nTGCs) in effective field theory (EFT) formalism that is used in current ATLAS Z(vv)y analysis. This model contains 6 EFT operators and supports MadGraph decomposition, including direct generation of cross terms (interference between two EFT operators). Previous models, that either do not contain all the operators, or do not support direct cross terms generation, will be outlined in the talk. Moreover, current status of the UFO models for nTGCs in vertex function formalism will be reviewed. Possible extensions for the models based on theoretical studies will be considered.

Speaker: Artur Semushin (A.Alikhanyan National Science Laboratory (AM))

LHC_EFT_09-10-2023.pdf

NTGC_all.zip