We present a two-loop analysis of the contributions to Higgs production via gluon-gluon fusion arising from the triple-gluon operator in the Standard Model effective field theory (SMEFT). Our discussion covers all aspects of renormalization group (RG) improved perturbation theory, including matching and running within the SMEFT. This study can therefore be seen as a blueprint of the intricacies and subtleties that arise in RG improved SMEFT calculations for collider processes beyond the leading order.

Germany

Ulrich Haisch

Higgs production from anomalous gluon dynamics

Dante Bigi

Switzerland

Marzia Bordone

Italy

Paolo Gambino

Andrea Piccione

Erratum to: QED effects in inclusive semi-leptonic

We calculate the one- and two-loop matching corrections in the Standard Model effective field theory (SMEFT) that impact electroweak precision measurements and flavour physics observables, focusing on the contributions of third-generation four-quark operators. Our results provide a crucial ingredient for a model-independent analysis of constraints on beyond the Standard Model physics that primarily affects the sector of third-generation four-quark operators. Concise analytic expressions are provided for all considered precision observables, which should facilitate their inclusion into global SMEFT analyses.

Luc Schnell

Precision tests of third-generation four-quark operators: one- and two-loop matching

We compute the corrections to the two-loop amplitudes for gg → h, gg → hg, qg → hq, and   <math> <mi>q</mi> <mover> <mi>q</mi> <mo>¯</mo> </mover> </math>  $$ q\overline{q} $$  → hg due to a modified cubic Higgs self-coupling. The exact dependence on the Higgs and top-quark masses across the entire 2 → 2 phase space is determined by numerically solving a system of differential equations for the relevant master integrals. The calculated amplitudes are crucial for evaluating the impact of the considered corrections on exclusive pp → hj production at the hadronic event level. As an application, we calculate the non-universal, kinematic-dependent cubic Higgs self-coupling corrections to the Higgs-boson transverse momentum distribution in gluon-gluon fusion Higgs production for arbitrary values of the transverse momentum.

Marco Niggetiedt

Exact two-loop amplitudes for Higgs plus jet production with a cubic Higgs self-coupling

The 2HDM+a model is one of the main models used in the interpretations of dark matter searches at the LHC. So far, all the 2HDM+a benchmarks considered by the ATLAS and CMS experiments are limited to a type-II Yukawa sector, in which the Higgs bosons A, H, and H  ±  are all constrained to be mass-degenerate and heavier than around 600 GeV. In this work, we present the first detailed study of 2HDM+a models with a type-I Yukawa sector, which, for moderate values of tan β, lift the constraints from flavour physics, allowing the extra Higgs bosons to be even lighter than the 125 GeV Higgs boson discovered at the LHC. We discuss several benchmarks where the A, H, and H  ±  states are not necessarily mass-degenerate and the signatures that arise in these models, some of which have not yet been explored at the LHC. We present the dominant channels in the studied benchmarks and the expected sensitivity in Run 2 data using truth-level analyses and discuss potential improvements in the experimental searches for Run 3.

Greece

Spyros Argyropoulos

Ilia Kalaitzidou

Novel collider signatures in the type-I 2HDM+a model

United Kingdom

Poland

Wojciech Bizoń

CERN

Luca Rottoli

United States

Zach Gillis

Brian Moser

Philipp Windischhofer

Addendum to: Constraints on the quartic Higgs self-coupling from double-Higgs production at future hadron colliders

In the context of the Standard Model effective field theory (SMEFT) the next-to-next-to-leading (NNLO) QCD corrections to the Higgsstrahlungs (Vh) processes in hadronic collisions are calculated and matched to a parton shower (PS). NNLO+PS precision is achieved for the complete sets of SMEFT operators that describe the interactions between the Higgs and two vector bosons and the couplings of the Higgs, a W or a Z boson, and light fermions. A POWHEG-BOX implementation of the computed NNLO SMEFT corrections is provided that allows for a realistic exclusive description of Vh production at the level of hadronic events. This feature makes it an essential tool for future Higgs characterisation studies by the ATLAS and CMS collaborations. Utilising our new Monte Carlo code the numerical impact of NNLO+PS corrections on the kinematic distributions in pp → Zh → ℓ + ℓ  −  h production is explored, employing well-motivated SMEFT benchmark scenarios.

Rhorry Gauld

SMEFT at NNLO+PS: Vh production

We analyse in detail the QED corrections to the total decay width and the moments of the electron energy spectrum of the inclusive semi-leptonic decay. Our calculation includes short-distance electroweak corrections, the complete 𝒪( ) partonic terms and leading-logarithmic QED effects up to $$ \mathcal{O}\left({\Lambda}_{\textrm{QCD}}^3/{m}_b^3\right) $$ . A comprehensive numerical comparison of our results against those obtained with the Monte Carlo (MC) tool PHOTOS is presented. While the comparison indicates good overall agreement, our computation contains QED effects not included in PHOTOS and should therefore better describe photon radiation to as measured by the -factories. Our calculations represent the first steps in the construction of a fully differential higher-order QED MC generator for inclusive semi-leptonic decays.

QED effects in inclusive semi-leptonic

Higgs decays displaced from the primary interaction vertex represent a striking experimental signature that is actively searched for by the ATLAS, CMS and LHCb collaborations. We point out that signals of this type appear in the context of the 2HDM+a model if the mixing angle θ of the two CP-odd weak spin-0 eigenstates is tiny and the dark matter (DM) sector is either decoupled or kinematically inaccessible. Utilising two suitable benchmark scenarios, we determine the constraints on the parameter space of the 2HDM+a model that are set by the existing LHC searches for long-lived particles (LLPs) in Higgs decays. We find that depending on the precise mass spectrum of the spin-0 states, mixing angles θ in the ballpark of a few 10 −8 to 10 −5 can be excluded based on LHC Run II data. This finding emphasises the unique role that searches for displaced signatures can play in constraining the parameter space of the 2HDM+a model. The ensuing DM phenomenology is also discussed. In particular, we show that parameter choices leading to an interesting LLP phenomenology can simultaneously explain the DM abundance observed in today’s Universe.

Long-lived particle phenomenology in the 2HDM+a model

Motivated by the long-standing hints of lepton-flavour non-universality in the b → cℓν and b → sℓ + ℓ  −  channels, we study Drell-Yan ditau production at the Large Hadron Collider (LHC). In the context of models with third-generation gauge vector leptoquarks (LQs), we calculate the complete   <math> <mi>O</mi> </math>  $$ \mathcal{O} $$ (α  s ) corrections to the pp → τ + τ  −  process, achieving next-to-leading order (NLO) plus parton shower (NLO+PS) accuracy using the POWHEG method. We provide a dedicated Monte Carlo code that evaluates the NLO QCD corrections on-the-fly in the event generation and use it to study the numerical impact of NLO+PS corrections on the kinematic distributions that enter the existing experimental searches for non-resonant ditau final states. Based on our phenomenological analysis we derive NLO accurate constraints on the masses and couplings of third-generation gauge vector LQs using the latest LHC ditau search results corresponding to an integrated luminosity of around 140 fb −1 of proton-proton collisions at   <math> <msqrt> <mi>s</mi> </msqrt> </math>  $$ \sqrt{s} $$  = 13 TeV. The presented NLO+PS generator allows for an improved signal modelling, making it an essential tool for future ATLAS and CMS searches for vector LQs in τ + τ  −  final states at LHC Run III and beyond.

Stefan Schulte

Drell-Yan production in third-generation gauge vector leptoquark models at NLO+PS in QCD