Lepton-quark fusion at Hadron colliders, precisely

Given the hints of lepton-flavour non-universality in B-meson decays, leptoquarks (LQs) are enjoying a renaissance. We propose novel Large Hadron Collider (LHC) searches for such hypothetical states that do not rely on strong production only, but can also receive important contributions from quark-lepton annihilation. For the cases of a resonant signal involving a bottom quark and a tau lepton (b + τ), a top quark and missing transverse energy ($$ {E}_T^{\mathrm{miss}} $$ E T miss ) and light-flavour jets plus $$ {E}_T^{\mathrm{miss}} $$ E T miss , we develop realistic analysis strategies and provide detailed evaluations of the achievable sensitivities for the corresponding LQ signatures at future LHC runs. Our analyses allow us to derive a series of stringent constraints on the masses and couplings of third-generation singlet vector LQs, showing that at LHC Run III and the high-luminosity LHC the proposed search channels can probe interesting parts of the LQ parameter space addressing the B-physics anomalies. In view of the reach of the proposed b + τ signature, we recommend that dedicated resonance searches for this final state should be added to the exotics search canon of both ATLAS and CMS.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 88%

Resonant third-generation leptoquark signatures at the Large Hadron Collider

Haisch

Polesello

2021

“…As it turns out, the t-channel contribution of figure 1 towards the leptoquark pair production at LHC becomes relevant only when the leptoquark interacts very strongly, i.e., with the couplings of order one, to the quarks of the first generation [55]. However, in this particular regime other processes such as a single leptoquark production [55][56][57][58], induced by the diagrams in panels (b) and (c) of figure 1, the Drell-Yan di-lepton production [59][60][61][62][63][64], and/or a resonant leptoquark production [65][66][67][68] might become equally capable of or even more important in constraining the leptoquark parameter space. Moreover, one also needs to take into account the experimental constraints from flavor physics, such as the Atomic Parity Violation ones, for a given l-q-LQ scenario to ensure its viability, especially within a large Yukawa coupling regime [69] space see ref.…”

Section: Introductionmentioning

confidence: 99%

Novel leptoquark pair production at LHC

Doršner

Fajfer

Lejlić

2021

We introduce a novel mechanism for the leptoquark pair production at LHC that is of a t-channel topology and is quark-quark initiated. This mechanism operates under fairly general conditions. One of them is that the two leptoquarks in question couple to the same lepton and the other one is that the fermion numbers of these two leptoquarks differ by two. The strength of the proposed mechanism provides an alternative way to the conventional processes to efficiently constrain the parameter space of the two leptoquark scenarios at LHC whenever the aforementioned conditions are met. We accordingly present one case study to outline the physics potential of this novel production mechanism.

“…To leading order in this scenario the effects on the Higgs phenomenology and on the B anomalies are decoupled, with the first ones being dominated byR 2 andS 1 , and the second ones by S 1 . Whereas current limits do not exclude an explanation of the B anomalies [72], one may wonder to which extent this possibility might be affected by single resonant LQ production searches at the LCH in the future [73][74][75]. Since the constraints arising from these searches would only impact on LQs coupled to leptons, they would not impose restrictions on the lightest LQ which in this scenario drives the increase of the double Higgs production and is mainly identified withS 1 , whose couplings to leptons we put to zero.…”

Section: B Anomaliesmentioning

confidence: 96%

Enhancement of the double Higgs production via leptoquarks at the LHC

Rold

Epele

Medina

et al. 2021

Measurements of single Higgs production and its decays are in good agreement with the Standard Model. There is still room for large modifications in double Higgs production at LHC, though these effects may be correlated with large corrections to other observables, in particular single Higgs production. In this work we address the issue of enhancing double Higgs production in the presence of scalar leptoquarks while satisfying all experimental constraints. We show at leading order that including more than one species of leptoquarks, large cubic interactions with the Higgs can lead to sizable enhancement of di-Higgs production cross section at LHC, while at the same time keeping other Higgs observables and precision measurements under control. For masses above 800 GeV these corrections are in general below 30%, whereas in a viable scenario in which one of the leptoquarks can be light, specifically in the mass range 400 − 600 GeV, we show that it is possible to roughly double the SM cross section for di-Higgs production, implying that possible first hints of it may be probed at the high luminosity LHC at $$ \mathcal{L} $$ L ∼ 2 ab−1.