Search for pair production of scalar leptoquarks decaying into first- or second-generation leptons and top quarks in proton–proton collisions at $$\sqrt{s}$$ = 13 TeV with the ATLAS detector

A search for pair production of scalar leptoquarks, each decaying into either an electron or a muon and a top quark, is presented. This is the first leptoquark search using ATLAS data to investigate top-philic cross-generational couplings that could provide explanations for recently observed anomalies in B meson decays. This analysis targets high leptoquark masses which cause the decay products of each resultant top quark to be contained within a single high-$$p_{\mathrm {T}}$$ p T large-radius jet. The full Run 2 dataset is exploited, consisting of $$139~\hbox {fb}^{-1}$$ 139 fb - 1 of data collected from proton–proton collisions at $$\sqrt{s}=13~\mathrm {TeV}$$ s = 13 TeV from 2015 to 2018 with the ATLAS detector at the CERN Large Hadron Collider. In the absence of any significant deviation from the background expectation, lower limits on the leptoquark masses are set at $$1480~\mathrm {GeV}$$ 1480 GeV and $$1470~\mathrm {GeV}$$ 1470 GeV for the electron and muon channel, respectively.

Confronting same-sign W-boson production with parton correlations

The future runs of LHC offer a unique opportunity to measure correlations between two partons inside the proton, which have never been experimentally detected. The process of interest is the production of two positively charged W-bosons decaying in the muon channel. We present a detailed analysis of proton-proton collisions at $$ \sqrt{s} $$ s = 13 TeV, where we combine Monte Carlo event generators with our calculations of parton correlations. We carefully compare double parton scattering to relevant background processes and trace a path towards a clean signal sample. Several observables are constructed to demonstrate the effect of parton correlations with respect to clear benchmark values for uncorrelated scatterings. We find that especially spin correlations can be responsible for large effects in the variables we study, because of their direct relation with the parton angular momentum and, therefore, the directions of the muon momenta. We estimate the significance of the measurements as a function of the integrated luminosity and conclude that the LHC has the potential to detect, or put strong limits on, parton correlations in the near future.

A COMPARATIVE STUDY ON B →K*ℓ+ ℓ- AND $B \to K_0^\ast (1430) \ell^+ \ell^-$ DECAYS IN THE SUPERSYMMETRIC MODELS

In this paper, we compare the branching ratio and rate difference of electron channel to muon channel of [Formula: see text] and B →K*ℓ+ℓ- decays, where [Formula: see text] is the p-wave scalar meson, in the supersymmetric models. MSSM with R parity is considered since considerable deviation from the standard model predictions can be obtained in B→Xs ℓ-ℓ+. Taking CQ1 and CQ2 about one which is consistent with the B→K*μ+μ- rate at low dileptonic invariant mass region (1 ≤ q2 ≤ 6 GeV 2). It is found that, firstly, the [Formula: see text] decay is measurable at LHC, secondly, in comparison with B →K*ℓ+ ℓ- decay a greater deviation in the [Formula: see text] decay can be seen. Measurement of these observables for the semileptonic rare [Formula: see text], in particular, at low q2 region can give valuable information about the nature of interactions within Standard Model or beyond.