We illustrate the importance of interference revival when higher order corrections are included, by presenting LO and NLO differential cross-sections and K-factors for three processes that are sensitive to the dimension-6 SMEFT operator <math><msub><mrow><mi>O</mi></mrow><mrow><mi>W</mi></mrow></msub></math>: Z-plus-two-jets (Zjj) production through Vector Boson Fusion (VBF), leptonic diboson WZ and Wγ. We show how lifting the interference suppression at LO, through suitable variables and cuts, is necessary to get reliable predictions at NLO. We also show bounds on <math><msub><mrow><mi>C</mi></mrow><mrow><mi>W</mi></mrow></msub></math> obtained from these observables.

Belgium

Céline Degrande

Matteo Maltoni

EFT observable stability under NLO corrections through interference revival

We present an update of the Universal FeynRules Output model format, commonly known as the UFO format, that is used by several automated matrix-element generators and high-energy physics software. We detail different features that have been proposed as extensions of the initial format during the last ten years, and collect them in the current second version of the model format that we coin the Universal Feynman Output format. Following the initial philosophy of the UFO, they consist of flexible and modular additions to address particle decays, custom propagators, form factors, the renormalisation group running of parameters and masses, and higher-order quantum corrections.

France

Luc Darmé

Germany

Claude Duhr

Benjamin Fuks

Mark Goodsell

Gudrun Heinrich

Switzerland

Valentin Hirschi

United States

Stefan Höche

Marius Höfer

Joshua Isaacson

Olivier Mattelaer

Thorsten Ohl

Italy

Davide Pagani

Jürgen Reuter

United Kingdom

Peter Richardson

Steffen Schumann

Hua-Sheng Shao

Frank Siegert

Marco Zaro

UFO 2.0: the ‘Universal Feynman Output’ format

We for the first time identify all the dimension-8 (dim-8) SMEFT operators that can have an interference with the SM with E 4/Λ4 enhancement in the high energy limit for the processes   <math> <mi>q</mi> <mover> <mi>q</mi> <mo>¯</mo> </mover> <mo>→</mo> <mi>WW</mi> <mo>/</mo> <mi>WZ</mi> </math>  $$ q\overline{q}\to WW/ WZ $$ . Our results therefore explicitly show that the non-interference observed for the dimension-six does not extend to dimension-eight. We compute the contributions of those dimension-8 operators to the cross-section at the 14 TeV Large Hadron Collider and compare the results with dimension-6 (dim-6) originated corrections at the order of dim-6-SM interference and dim-6 squared. We find one (two) dim-8 operator(s) can generate amplitudes of a similar order of magnitude compared with their dim-6 squared counterparts assuming unity dimensionless Wilson coefficients. During the study, new non-interference scenarios are found due to the selection rule of angular momentum as well as strong suppression due to the symmetric initial state for the proton-proton collider.

Hao-Lin Li

Impact of dimension-8 SMEFT operators on diboson productions

In this work, we study indirect photon signatures of leptophilic dark matter (DM) coming from Centaurus A (Cen A), where a DM density spike is believed to have survived to date contrary to the case of our galaxy. We consider a model where DM is a Majorana fermion which interacts with right-handed electrons via a scalar mediator. Assuming that the photons measured from the core of Cen A are coming from SM processes, we derive constraints on the average annihilation cross section which are 7 orders of magnitude stronger than the ones from measurements of the Galactic Center. Focusing on the allowed parameter space range, we calculate the flux of photons coming from the radiative DM-electron scattering in the active galactic nuclei (AGN) jets and the circular polarization asymmetry of these photons. We find that this flux is two orders of magnitude lower than the background but its circular polarization asymmetry can reach values close to 100%, indicating the need to experimentally exploit the high fraction of circular polarization in order to detect these interactions. Since the origin of the photons in the GeV-TeV range from Cen A is not completely clear and an exotic origin is compatible with the measurements as well, we also consider the scenario in which synchrotron radiation can only partially explain the photon flux and we fit the excess with signals coming from DM annihilation, finding a best fit for a DM candidate with a mass <math><msub><mi>m</mi><mover><mi>χ</mi><mo>˜</mo></mover></msub><mo>=</mo><mn>123</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math> and a coupling <math><msub><mi>a</mi><mi>R</mi></msub><mo>=</mo><mn>0.018</mn></math>.

Marina Cermeño

Luca Mantani

Signatures of leptophilic <math><mi>t</mi></math>-channel dark matter from active galactic nuclei

We show that only 10 (17) CP-odd operators of the SMEFT give the leading, i.e. least suppressed by the new physics scale, CP-violating contributions once we assume that all fermions are massless but the top (and bottom) quark(s). We start with a short review of previous analyses focusing on operators of our reduced basis and list different observables probing their CP violating effects by direct measurements at colliders and by indirect measurements in low-energy observables. Since CP-odd operators typically lead to phase space suppressed interferences, we quantify the efficiency to revive the interference for various observables found in the literature but also for new observables in diboson production. Our new observables are found to be more efficient on the whole experimental fiducial phase space and are complementary to those presented so far as they probe different combinations of operators and get their sensitivities from different regions of the phase space.

Julien Touchèque

A reduced basis for CP violation in SMEFT at colliders and its application to diboson production

We present the automation of one-loop computations in the standard-model effective field theory at dimension 6. Our general implementation, dubbed smeft@nlo, covers all types of operators: bosonic and two- and four-fermion ones. Included ultraviolet and rational counterterms presently allow for fully differential predictions, possibly matched to the parton shower, up to the one-loop level in the strong coupling or in four-quark operator coefficients. Exact flavor symmetries are imposed among light quark generations, and an initial focus is set on top-quark interactions in the fermionic sector. We illustrate the potential of this implementation with novel loop-induced and next-to-leading-order computations relevant for top-quark, electroweak, and Higgs-boson phenomenology at the LHC and future colliders.

Israel

Gauthier Durieux

Fabio Maltoni

Ken Mimasu

CERN

Eleni Vryonidou

China

Cen Zhang

Automated one-loop computations in the standard model effective field theory

Interferences are not positive-definite and therefore they can change sign over the phase space. If the contributions of the regions where the interference is positive and negative nearly cancel each other, interference effects are hard to measure. In this paper, we propose a method to quantify the ability of an observable to separate an interference positive and negative contributions and therefore to revive the interference effects in measurements. We apply this method to the anomalous gluon operator in the SMEFT for which the interference suppression is well-known. We show that we can get, for the first time, constraints on its coefficient using the interference only similar to those obtained by including the square of the new physics amplitude.

Reviving the interference: Framework and proof-of-principle for the anomalous gluon self-interaction in the SMEFT

We perform a global fit within the pseudo-Nambu-Goldstone Dark Matter (DM) model emerging from an additional complex scalar singlet with a softly broken global U (1) symmetry. Leading to a momentum-suppressed DM-nucleon cross section at tree level, the model provides a natural explanation for the null results from direct detection experiments. Our global fit combines constraints from perturbative unitarity, DM relic abundance, Higgs invisible decay, electroweak precision observables and latest Higgs searches at colliders. The results are presented in both frequentist and Bayesian statisical frameworks. Furthermore, post-processing our samples, we include the likelihood from gamma-ray observations of Fermi -LAT dwarf spheroidal galaxies and compute the one-loop DM-nucleon cross section. We find two favoured regions characterised by their dominant annihilation channel: the Higgs funnel and annihilation into Higgs pairs. Both are compatible with current Fermi -LAT observations, and furthermore, can fit the slight excess observed in four dwarfs in a mass range between about 30–300 GeV. While the former region is hard to probe experimentally, the latter can partly be tested by current observations of cosmic-ray antiprotons as well as future gamma-ray observations.

Chiara Arina

Ankit Beniwal

Jan Heisig

Australia

Andre Scaffidi

Global fit of pseudo-Nambu-Goldstone Dark Matter

We study the effects of new physics in double Higgs production at future e + e − colliders. In the Standard Model the chiral limit (m  e  = 0) plays an important role for this process, being responsible for the smallness of the tree-level diagrams with respect to the 1-loop contributions. In our work, we consider the possibility of an enhancement due to the contribution of Standard Model dimension-six effective operators. We show that there are only two relevant operators for this process that are not yet (strongly) constrained by other data. We perform a sensitivity study on the operator coefficients for several benchmark values of energy and integrated luminosity related to the proposed linear colliders such as CLIC, ILC and FCC-ee and we derive expected 95% CL limits for each benchmark scenario.

Brazil

Andres Vasquez

Canada

Alberto Tonero

Rogerio Rosenfeld

New physics in double Higgs production at future e + e − colliders

We present predictions for the total cross section for the production of a charged Higgs boson in the intermediate-mass range ( mH±∼mt ) at the LHC, focusing on a type-II two-Higgs-doublet model. Results are obtained at next-to-leading order (NLO) accuracy in QCD perturbation theory, by studying the full process pp→H±W∓bb¯ in the complex-(top)-mass scheme with massive bottom quarks. Compared to lowest-order predictions, NLO corrections have a sizeable impact: they increase the cross section by roughly 50% and reduce uncertainties due to scale variations by more than a factor of two. Our computation reliably interpolates between the low- and high-mass regime. Our results provide the first NLO prediction for charged Higgs production in the intermediate-mass range and therefore allow to have NLO accurate predictions in the full mH± range. The extension of our results to different realisations of the two-Higgs-doublet model or to the supersymmetric case is also discussed.

Rikkert Frederix

Maria Ubiali

Marius Wiesemann

Accurate predictions for charged Higgs production: Closing the mH±∼mt window