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18 papers found.
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Leptoquark toolbox for precision collider studies

Abstract We implement scalar and vector leptoquark (LQ) models in the universal FeynRules output (UFO) format assuming the Standard Model fermion content and conservation of baryon and lepton numbers. Scalar LQ implementations include next-to-leading order (NLO) QCD corrections. We report the NLO QCD inclusive cross sections in proton-proton collisions at 13 TeV, 14 TeV, and 27...

High- \(p_T\) dilepton tails and flavor physics

Eur. Phys. J. C High- pT dilepton tails and flavor physics Admir Greljo 0 1 David Marzocca 1 0 Faculty of Science, University of Sarajevo , Zmaja od Bosne 33-35, 71000 Sarajevo , Bosnia and

B-physics anomalies: a guide to combined explanations

Motivated by additional experimental hints of Lepton Flavour Universality violation in B decays, both in charged- and in neutral-current processes, we analyse the ingredients necessary to provide a combined description of these phenomena. By means of an Effective Field Theory (EFT) approach, based on the hypothesis of New Physics coupled predominantly to the third generation of...

Electroweak Higgs production with HiggsPO at NLO QCD

We present the HiggsPO UFO model for Monte Carlo event generation of electroweak VH and VBF Higgs production processes at NLO in QCD in the formalism of Higgs pseudo-observables (PO). We illustrate the use of this tool by studying the QCD corrections, matched to a parton shower, for several benchmark points in the Higgs PO parameter space. We find that, while being sizable and...

Knocking on new physics’ door with a scalar resonance

We speculate about the origin of the recent excess at \(\sim \)750 GeV in diphoton resonance searches observed by the ATLAS and CMS experiments using the first 13 TeV data. Its interpretation as a new scalar resonance produced in gluon fusion and decaying to photons is consistent with all relevant exclusion bounds from the 8 TeV LHC run. We provide a simple phenomenological...

Toward a coherent solution of diphoton and flavor anomalies

We propose a coherent explanation for the 750 GeV diphoton anomaly and the hints of deviations from Lepton Flavor Universality in B decays in terms a new strongly interacting sector with vectorlike confinement. The diphoton excess arises from the decay ofone of the pseudo-Nambu-Goldstone bosons of the new sector, while the flavor anomalies are a manifestation of the exchange of...

Anomalous triple gauge couplings in the effective field theory approach at the LHC

We discuss how to perform consistent extractions of anomalous triple gauge couplings (aTGC) from electroweak boson pair production at the LHC in the Standard Model Effective Field Theory (SMEFT). After recasting recent ATLAS and CMS searches in pp → W Z(W W ) → ℓ′νℓ+ℓ−(νℓ) channels, we find that: (a) working consistently at order Λ−2 in the SMEFT expansion the existing aTGC...

Pseudo-observables in electroweak Higgs production

We discuss how the leading electroweak Higgs production processes at the LHC, namely vector-boson fusion and Higgs\(+W/Z\) associated production, can be characterized in generic extensions of the Standard Model by a proper set of pseudo-observables (PO). We analyze the symmetry properties of these PO and their relation with the PO set appearing in Higgs decays. We discuss in...

On the breaking of lepton flavor universality in B decays

In view of recent experimental indications of violations of Lepton Flavor Universality (LFU) in B decays, we analyze constraints and implications of LFU interactions, both using an effective theory approach, and an explicit dynamical model. We show that a simple dynamical model based on a SU(2) L triplet of massive vector bosons, coupled predominantly to third generation fermions...

Higgs pseudo observables and radiative corrections

We show how leading radiative corrections can be implemented in the general description of \(h\rightarrow 4\ell \) decays by means of pseudo observables (PO). With the inclusion of such corrections, the PO description of \(h\rightarrow 4\ell \) decays can be matched to next-to-leading-order electroweak calculations both within and beyond the Standard Model (SM). In particular, we...

Electroweak bounds on Higgs pseudo-observables and \(h\rightarrow 4\ell \) decays

We analyze the bounds on the Higgs pseudo-observables following from electroweak constraints, under the assumption that the Higgs particle is the massive excitation of an \(\text {SU}(2)_L\) doublet. Using such bounds, detailed predictions for \(h\rightarrow 4\ell \) decay rates, dilepton spectra, and lepton-universality ratios are presented.

Cornering scalar leptoquarks at LHC

We study implications of large lepton-quark-leptoquark couplings for direct leptoquark searches at Large Hadron Collider. We present all existing flavor constraints on the strength of these couplings assuming that leptoquarks under consideration interact exclusively with charged leptons and quarks of the same generation. We find that these leptoquarks can have sizeable couplings...

Disentangling flavor violation in the top-Higgs sector at the LHC

We study the LHC phenomenology of flavor changing Yukawa couplings between the top quark, the Higgs boson, and either an up or charm quark. Such tuh or tch couplings arise for instance in models in which the Higgs sector is extended by the existence of additional Higgs bosons or by higher dimensional operators. We emphasize the importance of anomalous single top plus Higgs...

Pseudo-observables in Higgs decays

We define a set of pseudo-observables characterizing the properties of Higgs decays in generic extensions of the Standard Model with no new particles below the Higgs mass. The pseudo-observables can be determined from experimental data, providing a systematic generalization of the “\(\kappa \)-framework” so far adopted by the LHC experiments. The pseudo-observables are defined...

Dark Matter and gauged flavor symmetries

We investigate the phenomenology of flavored dark matter (DM). DM stability is guaranteed by an accidental \( {\mathcal{Z}}_3 \) symmetry, a subgroup of the standard model (SM) flavor group that is not broken by the SM Yukawa interactions. We consider an explicit realization where the quark part of the SM flavor group is fully gauged. If the dominant interactions between DM and...

Probing anomalous \( t\overline{t}Z \) interactions with rare meson decays

Anomalous couplings of the Z boson to top quarks are only marginally constrained by direct searches and are still sensitive to new particle dynamics at the TeV scale. Employing an effective field theory approach we consider the dimension-six operators which generate deviations from the standard-model vector and axial-vector interactions. We show that rare B and K meson decays...

New physics models facing lepton flavor violating Higgs decays at the percent level

We speculate about the possible interpretations of the recently observed excess in the h → τμ decay. We derive a robust lower bound on the Higgs boson coupling strength to a tau and a muon, even in presence of the most general new physics affecting other Higgs properties. Then we reevaluate complementary indirect constraints coming from low energy observables as well as from...

Constraining Higgs mediated dark matter interactions

We perform an analysis of Higgs portal models of dark matter (DM), where DM is light enough to contribute to invisible Higgs decays. Using effective field theory we show that DM can be a thermal relic only if there are additional light particles present with masses below a few 100 GeV. We give three concrete examples of viable Higgs portal models of light DM: (i) the SM extended...