Distinguishing Leptoquarks at the LHC/FCC

Beyond oblique contributions: $Δ$r and W-mass in models with scalar leptoquarks

We study the dominant non-universal contributions to muon decay for the five scalar leptoquarks (LQs) allowed by the Standard Model gauge symmetries. By using a common computational framework, we isolate the new-Physics (NP) one-loop corrections over the observable $Δr$ and explore the connection with the $W$ boson mass. We highlight the role of non-universal terms considering, for the $SU(2)$ doublet and triplet LQs, a completely degenerate scenario, thus cancelling/moderating the effects of the oblique parameters S,T and U . We determine simple formulas that exhibit the leading non-universal…

Sensitivity of Future Hadron Colliders to Leptoquark Pair Production in the Di-Muon Di-Jets Channel

We estimate the future sensitivity of the high luminosity (HL-) and high energy (HE-) modes of the Large Hadron Collider (LHC) and of a 100 TeV future circular collider (FCC-hh) to leptoquark (LQ) pair production in the muon-plus-jet decay mode of each LQ. Such LQs are motivated by the fact they provide an explanation for the neutral current $B-$anomalies. For each future collider, Standard Model (SM) backgrounds and detector effects are simulated. From these, sensitivities of each collider are found. Our measures of sensitivity are based upon a Run II ATLAS search, which we also use for valid…

Resonant leptoquark at NLO with POWHEG

Recent progress in calculating lepton density functions inside the proton and simulating lepton showers laid the foundations for precision studies of resonant leptoquark production at hadron colliders. Direct quark-lepton fusion into a leptoquark is a novel production channel at the LHC that has the potential to probe a unique parameter space for large masses and couplings. In this work, we build the first Monte Carlo event generator for a full-fledged simulation of this process at NLO for production, followed by a subsequent decay using the POWHEG method and matching to the parton showers uti…

The Case for Future Hadron Colliders From $B \to K^{(*)} μ^+ μ^-$ Decays

Recent measurements in $B \to K^{(*)} μ^+ μ^-$ decays are somewhat discrepant with Standard Model predictions. They may be harbingers of new physics at an energy scale potentially accessible to direct discovery. We estimate the sensitivity of future hadron colliders to the possible new particles that may be responsible for the anomalies: leptoquarks or $Z^\prime$s. We consider luminosity upgrades for a 14 TeV LHC, a 33 TeV LHC, and a 100 TeV $pp$ collider such as the FCC-hh. Coverage of $Z^\prime$ models is excellent: for narrow particles, with perturbative couplings that may explain the $b$-d…

Leptoquarks and Neutrino Masses at the LHC

The properties of light leptoquarks predicted in the context of a simple grand unified theory and their observability at the LHC are investigated. The SU(5) symmetry of the theory implies that the leptoquark couplings to matter are related to the neutrino mass matrix. We study the resulting connection between neutrino masses and mixing parameters and the leptoquark decays, and show that different light neutrino hierarchies imply distinctive leptoquark decay signatures. We also discuss low-energy constraints implied by searches for charged lepton flavour violation, studies of meson decays, and …

New Physics in $b \to s μμ$: FCC-hh or a Muon Collider?

Rare flavour-changing neutral-current transitions $b \to s μ^+ μ^-$ probe higher energy scales than what is directly accessible at the LHC. Therefore, the presence of new physics in such transitions, as suggested by the present-day LHCb anomalies, would have a major impact on the motivation and planning of future high-energy colliders. The two most prominent options currently debated are a proton-proton collider at 100 TeV (FCC-hh) and a multi-TeV muon collider (MuC). In this work, we compare the discovery prospects at these colliders on benchmark new physics models indirectly detectable in $b…

Type II Seesaw and tau lepton at the HL-LHC, HE-LHC and FCC-hh

The tau lepton plays important role in distinguishing neutrino mass patterns and determining the chirality nature in heavy scalar mediated neutrino mass models, in the light of the neutrino oscillation experiments and its polarization measurement. We investigate the lepton flavor signatures with tau lepton at LHC upgrades, i.e. HL-LHC, HE-LHC and FCC-hh, through leptonic processes from doubly charged Higgs in the Type II Seesaw. We find that for the channel with one tau lepton in final states, the accessible doubly charged Higgs mass at HL-LHC can reach 655 GeV and 695 GeV for the neutrino mas…

Flavorful leptoquarks at the LHC and beyond: Spin 1

Evidence for electron-muon universality violation that has been revealed in $b\to s \ell\ell$ transitions in the observables $R_{K,K^*}$ by the LHCb Collaboration can be explained with spin-1 leptoquarks in $SU(2)_L$ singlet $V_1$ or triplet $V_3$ representations in the ${\cal{O}}(1-10)$ TeV range. We explore the sensitivity of the high luminosity LHC (HL-LHC) and future proton-proton colliders to $V_1$ and $V_3$ in the parameter space connected to $R_{K,K^*}$-data. We consider pair production and single production in association with muons in different flavor benchmarks. Reinterpreting a rece…

通过顶极化对标量轻子夸克模型的喷注子结构探针研究

Jet Substructure Probe on Scalar Leptoquark Models via Top Polarization

本文研究了第三代标量轻子夸克模型$S_3$和$R_2$，通过喷注子结构和BDT多变量分析在14 TeV HL-LHC下有效提取信号并区分这两种模型，取得了高达$5.3\\,σ$的信号显著性和$3.2\\,σ$的模型分离度。

Can We Reach the Scale of New Physics Behind the $B$ Anomalies?

Indirect signs of new physics beyond the Standard Model may be appearing in $B \to K^{(*)}μ^+μ^-$ decays. If confirmed, the title question will be of paramount importance in determining the strategy for future colliders. We answer it by estimating the sensitivity to minimal, anomaly-compatible $Z^\prime$ and leptoquark models at the high luminosity LHC, 27 TeV HE-LHC, and 100 TeV FCC-hh; this conservative analysis outlines an upper bound on the available parameter space and the conditions for a reasonable guarantee of direct discovery.

Phenomenology of TeV-scale scalar Leptoquarks in the EFT

We examine new aspects of leptoquark (LQ) phenomenology using effective field theory (EFT). We construct a complete set of leading effective operators involving SU(2) singlets scalar LQ and the SM fields up to dimension six. We show that, while the renormalizable LQ-lepton-quark interaction Lagrangian can address the persistent hints for physics beyond the Standard Model in the B-decays $\bar B \to D^{(*)} τ\barν$, $\bar B \to \bar K \ell^+ \ell^-$ and in the measured anomalous magnetic moment of the muon, the LQ higher dimensional effective operators may lead to new interesting effects associ…

在带电轻子风味违反中的算子识别：利用RG演化的全球有效场论分析、极化可观测量和未来对撞机的贝叶斯模型判别

Operator Identification in Charged Lepton-Flavor Violation: Global EFT Analysis with RG Evolution, Polarization Observables, and Bayesian Model Discrimination at Future Colliders

本文通过全球有效场论分析，结合对撞机可观测量和贝叶斯判别，研究带电轻子风味违反的算子识别问题，探讨在多TeV能标下的算子相关性变化及极化不对称性应用。

通过多TeV缪子对撞机的缪子透镜探测希格斯和顶夸克相互作用

Probing Higgs and Top Interactions through the Muon Lens at multi-TeV Muon Colliders

研究多TeV缪子对撞机探测标准模型有效场论中六维算符的灵敏度，重点分析希格斯和顶夸克生产过程，通过模拟得出缪子-希格斯-规范及缪子-顶夸克相互作用的限制。