Charged Lepton Pairs Research Articles

Search for bottom-type vectorlike quark pair production in dileptonic and fully hadronic final states in proton-proton collisions at s=13 TeV

A search is described for the production of a pair of bottom-type vectorlike quarks (B VLQs) with mass greater than 1000 GeV. Each B VLQ decays into a b quark and a Higgs boson, a b quark and a Z boson, or a t quark and a W boson. This analysis considers both fully hadronic final states and those containing a charged lepton pair from a Z boson decay. The products of the H→bb boson decay and of the hadronic Z or W boson decays can be resolved as two distinct jets or merged into a single jet, so the final states are classified by the number of reconstructed jets. The analysis uses data corresponding to an integrated luminosity of 138 fb−1 collected in proton-proton collisions at s=13 TeV with the CMS detector at the LHC from 2016 to 2018. No excess over the expected background is observed. Lower limits are set on the B VLQ mass at the 95% confidence level. These depend on the B VLQ branching fractions and are 1570 and 1540 GeV for 100% B→bH and 100% B→bZ, respectively. In most cases, the mass limits obtained exceed previous limits by at least 100 GeV. © 2024 CERN, for the CMS Collaboration 2024 CERN

Probing dark photons from a light scalar at Belle II

In the minimal U(1) extension of the Standard Model (SM), a new gauge boson referred to as “dark photon” is predicted. The dark-photon mass can be generated from an additional Higgs mechanism associated with a dark scalar boson. At B-factories such as Belle II, large numbers of B-mesons are produced and can decay to a kaon plus the dark scalar via the latter’s mixing with the SM Higgs boson. We evaluate the sensitivity of Belle II for the case in which the dark scalar decays exclusively into a pair of dark photons via the new U(1) gauge coupling, and the dark photons are long lived owing to a small kinetic mixing ϵ. We study the experimental signature in which each dark photon decays into a pair of charged leptons, pions, or kaons, resulting in a pair of displaced vertices, and argue that the search is essentially background-free. We perform detailed Monte-Carlo simulations to determine the expected number of signal events at Belle II with an integrated luminosity of 50 ab−1, taking into account the efficiencies for both final-state-particle identification and displaced tracking. We find that for experimentally allowed values of the scalar mixing angle and kinematically allowed dark-photon and dark-scalar masses, the proposed search is uniquely sensitive to the medium-ϵ regime, which is currently mostly unexcluded by experiments.

Search for the anomalous ZZZ and ZZγ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ZZ\\gamma $$\\end{document} gauge couplings through the process e+e-→ZZ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$e^+e^- \\rightarrow ZZ $$\\end{document} with unpolarized and polarized beams

This work offers the constraints on the anomalous neutral triple gauge couplings for the process e+e-→ZZ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$e^+e^- \\rightarrow ZZ $$\\end{document} at the CLIC with s=3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sqrt{s}=3$$\\end{document} TeV. The realistic CLIC detector environments and their effects are considered in our analysis. The study is planned for the decays of produced Z bosons to a pair of charged leptons (electrons or muons) and neutrino pairs. The bounds on the anomalous neutral triple gauge couplings defining CP-violating CB~W/Λ4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C_{\\widetilde{B}W}/{\\Lambda ^4}$$\\end{document} coupling and three CP-conserving CWW/Λ4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C_{WW}/{\\Lambda ^4}$$\\end{document}, CBW/Λ4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C_{BW}/{\\Lambda ^4}$$\\end{document}, and CBB/Λ4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C_{BB}/{\\Lambda ^4}$$\\end{document} couplings are obtained. Also, the effects and advantages of polarization for incoming electron beams in these calculations are investigated.

NNLO QCD predictions of the asymmetry probe of the Z γ pair-production process

The paper presents for the first time a novel idea of exploiting asymmetry between differential cross sections of the off-shell Z γ pair-production in proton-proton (pp) collisions for the final states of a charged-lepton pair plus a photon pp → Z γ → l + l − γ (leptonic decay) and of a neutrino pair plus a photon (invisible decay). Asymmetry between the leptonic and invisible decays of the Z γ process is investigated by using fixed-order predictions through inclusion of next-to-next-to-leading (NNLO) radiative corrections in quantum chromodynamics (QCD) perturbation theory. NNLO QCD predictions are presented at various pp-collision energies as functions of several key observables including transverse momenta and azimuthal-angle separation, regarding the Z γ decay products. The predicted distributions for the Z γ asymmetry are provided based on realistic fiducial phase-space requirements in line with the related hadron-collider measurements. The predicted distributions are assessed at various pp-collision energies and in different phase-space regions such as with higher lepton-pair invariant mass or higher neutrino-pair transverse momentum requirements. The Z γ asymmetry is shown to be significantly sensitive in different regions of phase space including high- and high- regions. The Z γ asymmetry can therefore be translated into an important quantity for probing deviation from the Standard Model (SM) predictions. In this regard, the asymmetry probe is proposed as a sensitive indicator for indirect searches for physics beyond the SM encompassing high-mass resonances and dark-matter sector.

Codebase release 2.2 for HEJ

We present version 2.2 of the High Energy Jets (HEJ) Monte Carlo event generator for hadronic scattering processes at high energies. The new version adds support for two further processes of central phenomenological interest, namely the production of a W boson pair with equal charge together with two or more jets and the production of a Higgs boson with at least one jet. Furthermore, a new prediction for charged lepton pair production with high jet multiplicities is provided in the high-energy limit. The accuracy of HEJ 2.2 can be increased further through an enhanced interface to standard predictions based on conventional perturbation theory. We describe all improvements and provide extensive usage examples. HEJ 2.2 can be obtained from https://hej.hepforge.org.

Search for a high-mass dimuon resonance produced in association with b quark jets at s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s} $$\\end{document} = 13 TeV

A search for high-mass dimuon resonance production in association with one or more b quark jets is presented. The study uses proton-proton collision data collected with the CMS detector at the LHC corresponding to an integrated luminosity of 138 fb−1 at a center-of-mass energy of 13 TeV. Model-independent limits are derived on the number of signal events with exactly one or more than one b quark jet. Results are also interpreted in a lepton-flavor-universal model with Z′ boson couplings to a bb quark pair (gb), an sb quark pair (gbδbs), and any same-flavor charged lepton (gℓ) or neutrino pair (gν), with |gν| = |gℓ|. For a Z′ boson with a mass mZ′\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {m}_{{\ extrm{Z}}^{\\prime }} $$\\end{document} = 350 GeV (2 TeV) and |δbs| < 0.25, the majority of the parameter space with 0.0057 < |gℓ| < 0.35 (0.25 < |gℓ| < 0.43) and 0.0079 < |gb| < 0.46 (0.34 < |gb| < 0.57) is excluded at 95% confidence level. Finally, constraints are set on a Z′ model with parameters consistent with low-energy b → sℓℓ measurements. In this scenario, most of the allowed parameter space is excluded for a Z′ boson with 350 < mZ′\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {m}_{{\ extrm{Z}}^{\\prime }} $$\\end{document} < 500 GeV, while the constraints are less stringent for higher mZ′\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {m}_{{\ extrm{Z}}^{\\prime }} $$\\end{document} hypotheses. This is the first dedicated search at the LHC for a high-mass dimuon resonance produced in association with multiple b quark jets, and the constraints obtained on models with this signature are the most stringent to date.

Predictions of the ratio and asymmetry probes of the invisible Z-boson decay

Higher-order predictions through the combined accuracy including next-to-leading order (NLO) electroweak (EW) and next-to-NLO (NNLO) quantum chromodynamics (QCD) corrections in underlying perturbation theories are presented thoroughly for the invisible decay of the Z boson into neutrino pair relative to its decay into charged-lepton pair (leptonic decay). The combined NNLO QCD+NLO EW predictions are achieved based on the fully-differential calculations of cross sections of both the invisible and leptonic processes in proton-proton (pp) collisions at 13 TeV center-of-mass energy. Differential distributions of cross-section ratios of the invisible process to the leptonic process are presented as a function of the transverse momentum of the Z boson . For the first time, the predictions for differential distributions of cross-section asymmetries between the invisible process and the leptonic process are presented in bins of the . The cross-section ratio and asymmetry distributions, which are referred to as the invisible probes, are considered to be important for controlling the invisible process by the leptonic process of the Z boson and probing deviation from the Standard Model (SM) for new-physics searches. The predictions are extensively presented beyond the Z-boson mass resonance region to assess the potential of the invisible ratio and asymmetry probes for new-phenomena searches in high-invariant mass region of the lepton-pair final states. Various tests with threshold requirements of transverse momenta of neutrino pair and leptons are performed to assess the impact on the combined predictions. The invisible ratio and asymmetry probes are proposed to be important probes for indirect searches of new-physics scenarios.

Cross-section measurements for the production of a Z boson in association with high-transverse-momentum jets in pp collisions at sqrt{s} = 13 TeV with the ATLAS detector

Cross-section measurements for a Z boson produced in association with high-transverse-momentum jets (pT ≥ 100 GeV) and decaying into a charged-lepton pair (e+e−, μ+μ−) are presented. The measurements are performed using proton–proton collisions at sqrt{s} = 13 TeV corresponding to an integrated luminosity of 139 fb−1 collected by the ATLAS experiment at the LHC. Measurements of angular correlations between the Z boson and the closest jet are performed in events with at least one jet with pT ≥ 500 GeV. Event topologies of particular interest are the collinear emission of a Z boson in dijet events and a boosted Z boson recoiling against a jet. Fiducial cross sections are compared with state-of-the-art theoretical predictions. The data are found to agree with next-to-next-to-leading-order predictions by NNLOjet and with the next-to-leading-order multi-leg generators MadGraph5_aMC@NLO and Sherpa.

Near or far detectors? A case study for long-lived particle searches at electron-positron colliders

We explore the discovery potential for long-lived particles at the 250-GeV ILC. The goal is to investigate possible gains of a dedicated far detector over the main detector ILD. For concreteness, we perform our study for sub-GeV axion-like particles $a$ produced via $e^+e^- \to a \gamma$ or $e^+e^- \to Z \gamma \to (a\gamma)\gamma$ and decaying into pairs of charged leptons. In the ideal case of zero background and perfect detection efficiency, we find that far detectors placed in the planned underground cavities or a large cuboid on the ground can enhance the sensitivity to long-lived pseudo-scalars at best moderately. On the other hand, the ILD itself is a perfect environment to search for long-lived particles, due to its excellent angular coverage and radial thickness. For long-lived particles produced with cross sections of a few picobarns, the ILD could probe lifetimes up to 300$\,$ns, or proper decay lengths up to 100$\,$m, in 250$\,$fb$^{-1}$ of data. For axion-like particles produced through weak interactions, the ILC can reach an even higher sensitivity than searches for displaced vertices in meson decays at Belle II. Our findings apply similarly to other proposed electron-positron experiments with a high angular coverage, such as the FCC-ee and CEPC.

Electromagnetic interaction of low transverse momentum charged leptons with heavy nuclei in ultra-peripheral ultra-relativistic heavy-ion collisions

The photon–photon interaction in ultra-relativistic heavy-ion collision is a source of the charged lepton pairs. The photon-photon fusion leads to the lepton creation in broad configuration space around the “collision” point. Those created close to heavy nuclei may undergo strong electromagnetic interaction with them. The impact parameter space distributions of electrons/positrons and charged muons are calculated within the b-space EPA model of such collisions. The evolution of e^+/e^- and mu ^+/mu ^- distributions due to the electromagnetic interaction of leptons with nuclei is studied, and the distortion of rapidity and transverse momentum distributions are shown. A part of the analysis is independent of the production model. We show the first exploratory results for the reaction Pb + Pb at sqrt{s_{NN}} = 17.3 GeV (SPS) and 200 GeV (RHIC) energies. We provide results for selected creation points and when integrating over their positions as dictated by the b-space EPA model. We observe sizeable effects for e^+ / e^- and much smaller effects for mu ^+ / mu ^-. We predict a possible sizeable accumulation of leptons with rapidities close to the beam rapidity. The EM effects lead to asymmetry in the production of e^+ and e^- or mu ^+ and mu ^-.

Muon anomalous magnetic dipole moment in the μ νSSM * *Supported by the National Natural Science Foundation of China (11705045, 11535002, 12075074), the Natural Science Foundation for Distinguished Young Scholars of Hebei Province (A2022201017), the Natural Science Foundation of Guangxi Autonomous Region (2022GXNSFDA035068), the youth top-notch talent support program of the Hebei Province, and Midwest Universities Comprehensive Strength Promotion project

Recently, the Muon g-2 experiment at Fermilab measured the muon anomalous magnetic dipole moment (MDM), , and reported that the new experimental average increases the difference between the experiment and the standard model (SM) prediction to 4.2σ. In this work, we reanalyze the muon anomalous MDM at the two-loop level in the μ from the ν Supersymmetric Standard Model ( SSM) combined with the updated experimental average. The SSM can explain the current difference between the experimental measurement and the SM theoretical prediction for the muon anomalous MDM, constrained by the 125 GeV Higgs boson mass and decays, the rare decay , and so on. We also investigate the anomalous MDM of the electron and tau lepton, and , at the two-loop level in the SSM. In addition, the decaying of the 125 GeV Higgs boson into a pair of charged leptons in the SSM is analyzed.

The light leptophilic gauge boson Zx and the leptonic decays of charged pseudoscalar mesons

The light leptophilic gauge boson Zx predicted by the U(1)Lx models can contribute to the lepton flavor universality (LFU) parameter Rℓ/ℓ′P and the leptonic decays P→ℓνℓℓ′ℓ′¯ via the process P→ℓνℓZx with Zx decaying into a pair of neutrinos or charged leptons, where P denotes the charged pseudoscalar mesons π±, K±, D(s)± or B±. Using the corresponding experimental data, we obtain the constraints on different U(1)Lx models. The most strict constraints on the U(1)Lx models come from the decay K+→μ+νμe+e−.

Doubly charged Higgs production at future ep colliders * *Supported in part by National Natural Science Foundation of China (11605075, 11635009) and Natural Science Foundation of Shandong Province (ZR2017JL006, ZR2021QA040)

The Higgs sector of the standard model can be extended by introducing an Higgs triplet Δ to generate tiny neutrino masses in the framework of the type-II seesaw mechanism. In this paper, we study the pair production of the introduced Higgs triplet at future colliders. The corresponding production cross sections via the vector boson fusion process at the FCC-ep and ILC FCC are predicted, where the production of a pair of doubly charged Higgs is found to be dominant and then used to investigate the collider phenomenology of the Higgs triplet. Depending on the size of the Higgs triplet vacuum expectation value, the doubly charged Higgs may decay into a pair of same-sign charged leptons or a pair of same-sign W bosons. To explore the discovery potential of the doubly charged Higgs at future colliders, we discuss these two decay scenarios in detail and show their detection sensitivity based on the mass of the doubly charged Higgs.

Longitudinal Z-boson polarization and the Higgs boson production cross section at the Large Hadron Collider

Charged lepton pairs are produced copiously in high-energy hadron collisions via electroweak gauge boson exchange, and are one of the most precisely measured final states in proton-proton collisions at the Large Hadron Collider (LHC). We propose that measurements of lepton angular distributions can be used to improve the accuracy of theoretical predictions for Higgs boson production cross sections at the LHC. To this end, we exploit the sensitivity of the lepton angular coefficient associated with the longitudinal Z-boson polarization to the parton density function (PDF) for gluons resolved from the incoming protons, in order to constrain the Higgs boson cross section from gluon fusion processes. By a detailed numerical analysis using the open-source platform xFitter, we find that high-statistics determinations of the longitudinally polarized angular coefficient at the LHC Run III and high-luminosity HL-LHC improve the PDF systematic uncertainties of the Higgs boson cross section predictions by 50% over a broad range of Higgs boson rapidities.

One-loop electroweak radiative corrections to charged lepton pair production in photon-photon collisions

We provide high-precision predictions for muon-pair and tau-pair productions in a photon-photon collision by considering a complete set of one-loop-level scattering amplitudes, i.e., electroweak (EW) corrections together with soft and hard QED radiation. Accordingly, we present a detailed numerical discussion with particular emphasis on the pure QED corrections as well as genuinely weak corrections. The effects of angular and initial beam polarization distributions on production rates are also discussed. An improvement is observed by a factor of two with oppositely polarized photons. Our results indicate that the one-loop EW radiative corrections enhance the Born cross section and the total relative correction is typically about 10% for both production channels. It appears that the full EW corrections to $\ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\rightarrow}{\ensuremath{\ell}}^{\ensuremath{-}}{\ensuremath{\ell}}^{+}$ are required to match a percent level accuracy.

Phenomenology of vector-like leptons with Deep Learning at the Large Hadron Collider

In this paper, a model inspired by Grand Unification principles featuring three generations of vector-like fermions, new Higgs doublets and a rich neutrino sector at the low scale is presented. Using the state-of-the-art Deep Learning techniques we perform the first phenomenological analysis of this model focusing on the study of new charged vector-like leptons (VLLs) and their possible signatures at CERN’s Large Hadron Collider (LHC). In our numerical analysis we consider signal events for vector-boson fusion and VLL pair production topologies, both involving a final state containing a pair of charged leptons of different flavor and two sterile neutrinos that provide a missing energy. We also consider the case of VLL single production where, in addition to a pair of sterile neutrinos, the final state contains only one charged lepton. We propose a novel method to identify missing transverse energy vectors by comparing the detector response with Monte-Carlo simulated data. All calculated observables are provided as data sets for Deep Learning analysis, where a neural network is constructed, based on results obtained via an evolutive algorithm, whose objective is to maximise either the accuracy metric or the Asimov significance for different masses of the VLL. Taking into account the effect of the three analysed topologies, we have found that the combined significance for the observation of new VLLs at the high-luminosity LHC can range from 5.7σ, for a mass of 1.25 TeV, all the way up to 28σ if the VLL mass is 200 GeV. We have also shown that by the end of the LHC Run-III a 200 GeV VLL can be excluded with a confidence of 8.8 standard deviations. The results obtained show that our model can be probed well before the end of the LHC operations and, in particular, providing important phenomenological information to constrain the energy scale at which new gauge symmetries emergent from the considered Grand Unification picture can be manifest.

Signatures of a flavor changing Z′ boson in Bq → γZ′

Rare B meson decays offer an opportunity to probe a light hidden Z′ boson. In this work we explore a new channel Bq→γZ′ (q=d,s) followed by a cascade decay of Z′ into an invisible (neutrino or dark matter) or charged lepton pair ℓ+ℓ− (ℓ=e,μ). The study is based on a simplified effective model where the down quark sector has tiny flavor-changing neutral current couplings with Z′. For the first time, we calculate BR(Bq→γZ′) at the leading power of 1/mb and 1/Eγ. Confronting with the strong constraints from semi-invisible decays of B meson, we find that the branching ratio for Bd→invisible+γ can be larger than its Standard Model background prediction, leaving a large room for new physics, in particular for light dark matter. Additionally, the branching ratio for Bd→e+e−γ can also be sizable when the corresponding flavor violating Z′ coupling to quarks is of the axial-vector type. On the other hand, the predicted branching ratios of Bd→μ+μ−γ and Bs→ℓ+ℓ−γ are severely constrained by the experimental measurements.

Measurements of production cross sections of WZ and same-sign WW boson pairs in association with two jets in proton-proton collisions at [formula omitted

Measurements of production cross sections of WZ and same-sign WW boson pairs in association with two jets in proton-proton collisions at s=13TeV at the LHC are reported. The data sample corresponds to an integrated luminosity of 137fb−1, collected with the CMS detector during 2016–2018. The measurements are performed in the leptonic decay modes ▪ and ▪, where ℓ,ℓ′=e, ▪. Differential fiducial cross sections as functions of the invariant masses of the jet and charged lepton pairs, as well as of the leading-lepton transverse momentum, are measured for W±W± production and are consistent with the standard model predictions. The dependence of differential cross sections on the invariant mass of the jet pair is also measured for WZ production. An observation of electroweak production of WZ boson pairs is reported with an observed (expected) significance of 6.8 (5.3) standard deviations. Constraints are obtained on the structure of quartic vector boson interactions in the framework of effective field theory.

Observation of the associated production of a top quark and a Z boson in pp collisions at sqrt{s} = 13 TeV with the ATLAS detector

Single top-quark production in association with a Z boson, where the Z boson decays to a pair of charged leptons, is measured in the trilepton channel. The proton-proton collision data collected by the ATLAS experiment from 2015 to 2018 at a centre-of-mass energy of 13 TeV are used, corresponding to an integrated luminosity of 139 fb−1. Events containing three isolated charged leptons (electrons or muons) and two or three jets, one of which is identified as containing a b-hadron, are selected. The main backgrounds are from toverline{t}Z and diboson production. Neural networks are used to improve the background rejection and extract the signal. The measured cross-section for tℓ+ℓ−q production, including non-resonant dilepton pairs with {m}_{{mathrm{ell}}^{+}{mathrm{ell}}^{-}} > 30 GeV, is 97 ± 13 (stat.) ± 7 (syst.) fb, consistent with the Standard Model prediction.

Left-right supersymmetric option at a high-energy upgrade of the LHC

We investigate the possibility that a minimal realization of left-right supersymmetry can be reachable at a high-energy upgrade of the LHC, expected to operate at a center-of-mass energy of 27 TeV. This minimal scenario has a relatively light $SU(2)_R$ doubly-charged Higgs boson, which could decay dominantly into tau-lepton pairs. We explore the associated signals comprised of at least three hadronically-decaying taus, or with at least two hadronic taus and one same-sign-same-flavor charged lepton pair. Our analysis shows that the former signature is challenging to use for getting handles on the signal due to the large corresponding background, and that the latter one can lead to a handful of new physics events in an almost background-free environment. We however find that a signal comprised of three hadronically-decaying tau leptons is likely to be observed at a low luminosity of proton-proton collisions at a 27 TeV upgrade of the LHC.