We show that stringent limits on leptoquarks that couple to first-generation quarks and left-handed electrons or muons can be derived from the spectral shape of the charged-current Drell-Yan process (pp → l AE ν) at run 2 of the LHC. We identify and examine all six leptoquark species that can generate such a monolepton signal, including both scalar and vector leptoquarks, and find cases where the leptoquark exchange interferes constructively, destructively or not at all with the Standard Model signal. When combined with the corresponding leptoquark-mediated neutral-current (pp → l þ l − ) process, we find the most stringent limits obtained to date, outperforming bounds from pair production and atomic parity violation. We show that, with 3000 fb −1 of data, combined measurements of the transverse mass in pp → l AE ν events and invariant mass in pp → l þ l − events can probe masses between 8 and 18 TeV, depending on the species of leptoquark, for electroweak-sized couplings. In light of such robust sensitivities, we strongly encourage the LHC experiments to interpret Drell-Yan (dilepton and monolepton) events in terms of leptoquarks, alongside usual scenarios like Z 0 bosons and contact interactions.

The mirror twin Higgs model (MTH) is a solution to the Higgs hierarchy problem that provides well-predicted cosmological signatures with only three extra parameters: the temperature of the twin sector, the abundance of twin baryons, and the vacuum expectation value (VEV) of twin electroweak symmetry breaking. These parameters specify the behavior of twin radiation and the acoustic oscillations of twin baryons, which lead to testable effects on the cosmic microwave background (CMB) and large-scale structure (LSS). While collider searches can only probe the twin VEV, through a fit to cosmological data we show that the existing CMB (Planck18 TTTEEE+lowE+lowT+lensing) and LSS (KV450) data already provide useful constraints on the remaining MTH parameters. Additionally, we show that the presence of twin radiation in this model can raise the Hubble constant H0 while the scattering twin baryons can reduce the matter fluctuations S8, which helps to relax the observed H0 and S8 tensions simultaneously. This scenario is different from the typical ΛCDM + ∆Neff model, in which extra radiation helps with the Hubble tension but worsens the S8 tension. For instance, when including the SH0ES and 2013 Planck SZ data in the fit, we find that a universe with ≳ 20% of the dark matter comprised of twin baryons is preferred over ΛCDM by ∼ 4σ. If the twin sector is indeed responsible for resolving the H0 and S8 tensions, future measurements from the Euclid satellite and CMB Stage 4 experiment will further measure the twin parameters to O(1 − 10%)-level precision. Our study demonstrates how models with hidden naturalness can potentially be probed using precision cosmological data.

There has been persistent disagreement between the Standard Model (SM) prediction and experimental measurements of R D ( * ) = B(B → D ( * ) τντ )/B(B → D ( * ) lν l ) (l = e, µ). This anomaly may be addressed by introducing interactions beyond the Standard Model involving new states, such as leptoquarks. Since the processes involved are quark flavor changing, any new states would need to couple to at least two different generations of quarks, requiring a non-trivial flavor structure in the quark sector while avoiding stringent constraints from flavor-changing neutral current processes. In this work, we look at scalar leptoquarks as a possible solution for the R D ( * ) anomaly under the assumption of minimal flavor violation (MFV). We investigate all possible representations for the leptoquarks under the SM quark flavor symmetry group, consistent with asymptotic freedom. We consider constraints on their parameter space from self-consistency of the MFV scenario, perturbativity, the FCNC decay b → sνν and precision electroweak observables. We find that none of the scalar leptoquarks can explain the R D ( * ) anomaly while simultaneously avoiding all constraints within this scenario. Thus scalar leptoquarks with MFV-generated quark couplings do not work as a solution to the R D ( * ) anomaly.

We find constraints on R-Parity Violating (RPV) couplings of the minimal supersymmetric standard model, using Drell-Yan differential cross sections at the LHC. Specifically, we look at the constraints on λ LQD c couplings from monolepton and dilepton data published by ATLAS, with either electrons or muons in the final state. Out of the 18 RPV couplings to which the LHC is at least potentially sensitive by this technique, we find new limits on 12 (or 13) of them, for squarks masses above 1 (or 2) TeV. We also show that one can employ our techniques to achieve significantly stronger bounds at a high-luminosity upgrade of the LHC.