One-loop corrections to ALP couplings

The plethora of increasingly precise experiments which hunt for axion-like particles (ALPs), as well as their widely different energy reach, call for the theoretical understanding of ALP couplings at loop-level. We derive the one-loop contributions to ALP-SM effective couplings, including finite corrections. The complete leading-order — dimension five — effective linear Lagrangian is considered. The ALP is left off-shell, which is of particular impact on LHC and accelerator searches of ALP couplings to γγ, ZZ, Zγ, WW, gluons and fermions. All results are obtained in the covariant Rξ gauge. A few phenomenological consequences are also explored as illustration, with flavour diagonal channels in the case of fermions: in particular, we explore constraints on the coupling of the ALP to top quarks, that can be extracted from LHC data, from astrophysical sources and from Dark Matter direct detection experiments such as PandaX, LUX and XENON1T. Furthermore, we clarify the relation between alternative ALP bases, the role of gauge anomalous couplings and their interface with chirality-conserving and chirality-flip fermion interactions, and we briefly discuss renormalization group aspects.

Probing anomalous γγγZ couplings through γZ production in γγ collisions at the CLIC

We have estimated the sensitivity to the anomalous couplings of the γγγZ vertex in the γγ → γZ scattering of the Compton backscattered photons at the CLIC. Both polarized and unpolarized collisions at the e+e− energies 1500 GeV and 3000 GeV are addressed, and anomalous contributions to helicity amplitudes are derived. The differential and total cross sections are calculated. We have obtained 95% C.L. exclusion limits on the anomalous quartic gauge couplings (QGCs). They are compared with corresponding bounds derived for the γγγZ couplings via γZ production at the LHC. The constraints on the anomalous QGCs are one to two orders of magnitude more stringent that at the HL-LHC. The partial-wave unitarity constraints on the anomalous couplings are examined. It is shown that the unitarity is not violated in the region of the anomalous QGCs studied in the paper.

Anomalous couplings in Higgs-boson pair production at approximate NNLO QCD

We combine NLO predictions with full top-quark mass dependence with approximate NNLO predictions for Higgs-boson pair production in gluon fusion, including the possibility to vary coupling parameters within a non-linear Effective Field Theory framework containing five anomalous couplings for this process. We study the impact of the anomalous couplings on various observables, and present Higgs-pair invariant-mass distributions at seven benchmark points characterising different mhh shape types. We also provide numerical coefficients for the approximate NNLO cross section as a function of the anomalous couplings at $$ \sqrt{s} $$ s = 14 TeV.

Sensitivity measuring expected on the electromagnetic anomalous couplings in the tt̄γ vertex at the FCC-he

Starting from an effective Lagrangian for the [Formula: see text] interaction of the top-quark, we consider the electroweak production cross-section via charged current and through the [Formula: see text] signal. Further, we derive the sensitivity expected for the magnetic dipole moment [Formula: see text] and the electric dipole moment [Formula: see text] of the top-quark at the Future Circular Collider-hadron electron (FCC-he). We present our study for [Formula: see text], 10 TeV, [Formula: see text], 100, 300, 500, 1000 fb[Formula: see text], [Formula: see text] and [Formula: see text], 80%, [Formula: see text], respectively. We find that the sensitivity estimated on dipole moments of the top-quark is of the order of magnitude [Formula: see text] for both hadronic and leptonic decay modes of [Formula: see text]: [Formula: see text] and [Formula: see text] at 95% C.L. in the hadronic channel with unpolarized electron beam [Formula: see text]. Our results regarding the polarized electron beam for [Formula: see text] and [Formula: see text] are [Formula: see text], [Formula: see text] and [Formula: see text], [Formula: see text] at 95% C.L. in the hadronic channel. The corresponding results for the leptonic channel with [Formula: see text], 80% [Formula: see text] are [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], [Formula: see text], respectively. The results for [Formula: see text] and [Formula: see text] in the leptonic channel are weaker than those corresponding to the hadronic channel by a factor of 0.75. Given these prospective sensitivities, the FCC-he is an alternative to study the anomalous couplings of the quark-top that would complement the studies of the LHC with cleaner environments.

A non-linear EFT description of gg → H H at NLO interfaced to POWHEG

We present the implementation of Higgs boson pair production in gluon fusion within a non-linear Effective Field Theory framework containing five anomalous couplings for this process. The code, available within the POWHEG-BOX-V2, includes full NLO QCD corrections with massive top quarks. All five couplings can be modified by the user. We show mhh distributions at seven benchmark points provided by an mhh shape analysis at NLO and showered $$ {p}_T^{hh} $$ p T hh distributions resulting from an interface to PYTHIA-8 and HERWIG-7.2.

Constraints on the Anomalous Wtb Couplings from B-Physics Experiments

We analyze constraints on the anomalous Wtb couplings from B-physics experiments, performing a correlated analysis and allowing all anomalous couplings to differ simultaneously from their Standard Model (SM) values. The B-physics observables allow one to probe three linear combinations out of the four anomalous couplings, which parameterize the Wtb vertex under the assumption that the SM symmetries remain the symmetries of the effective theory. The constraints in this work are obtained by taking into account the following B-physics observables: the B¯0−B0 oscillations, the leptonic B→μ+μ− decays, the inclusive radiative B→Xsγ decays, and the differential branching fractions in the semileptonic inclusive B→Xsμ+μ− and exclusive B→(K,K*)μ+μ− decays at small q2, with q the momentum of the μ+μ− pair. We find that the SM values of the anomalous couplings belong to the 95% CL allowed region obtained this way, but lie beyond the 68% allowed region. We also report that the distributions of the anomalous couplings obtained within our scenario differ from the results of the 1D scenario, when only one of the couplings is allowed to deviate from its SM value.

Exclusive Diffraction at the LHC On behalf of the ATLAS, LHCb, CMS and TOTEM experiments

In this report, we describe the most recent results on exclusive diffraction from the ATLAS, CMS, LHCb, TOTEM experiments at the LHC concerning exclusive pions, J/Ψ, Ψ(2S ), dilepton, diphoton, WW productions and prospects concerning the search for anomalous couplings and axion-like particle production.