Search for a singly produced third-generation scalar leptoquark decaying to a $τ$ lepton and a bottom quark in proton-proton collisions at $\sqrt{s} =$ 13 TeV
A search is presented for a singly produced third-generation scalar leptoquark decaying to a $τ$ lepton and a bottom quark. Associated production of a leptoquark and a $τ$ lepton is considered, leading to a final state with a bottom quark and two $τ$ leptons. The search uses proton-proton collision data at a center-of-mass energy of 13 TeV recorded with the CMS detector, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. Upper limits are set at 95% confidence level on the production cross section of the third-generation scalar leptoquarks as a function of their mass. From a comparison of the results with the theoretical predictions, a third-generation scalar leptoquark decaying to a $τ$ lepton and a bottom quark, assuming unit Yukawa coupling ($λ$), is excluded for masses below 740 GeV. Limits are also set on $λ$ of the hypothesized leptoquark as a function of its mass. Above $λ=$ 1.4, this result provides the best upper limit on the mass of a third-generation scalar leptoquark decaying to a $τ$ lepton and a bottom quark.
A search for leptoquarks produced singly and in pairs in proton-proton collisions is presented. We consider the leptoquark (LQ) to be a scalar particle of charge -1/3$e$ coupling to a top quark plus a tau lepton ($\mathrm{t}τ$) or a bottom quark plus a neutrino ($\mathrm{b}ν$), or a vector particle of charge +2/3$e$, coupling to $\mathrm{t}ν$ or $\mathrm{b}τ$. These choices are motivated by models that can explain a series of anomalies observed in the measurement of B meson decays. In this analysis the signatures $\mathrm{t}τν\mathrm{b}$ and $\mathrm{t}τν$ are probed, using data recorded by th…
We have searched for third generation leptoquarks (LQ3) using 1.05 inverse femtobarns of data collected with the D0 detector at the Fermilab Tevatron Collider operating at sqrt(s)=1.96 TeV. We set a 95% C.L. lower limit of 210 GeV on the mass of a scalar LQ3 state decaying solely to a b quark and a tau lepton.
We present the results of a search for leptoquark (LQ) pairs in (85.2 +- 3.7) pb^{-1} of p anti-p collider data collected by the D0 experiment at the Fermilab Tevatron. We observe no evidence for leptoquark production and set a limit on sigma(p anti-p -> LQ anti-LQ -> neutrino neutrino + jets) as a function of the mass of the leptoquark (m_{LQ}). Assuming the decay LQ -> neutrino q, we exclude scalar leptoquarks for m_{LQ} < 98 GeV/c^2, and vector leptoquarks for m_{LQ} < 200 GeV/c^2 and coupling which produces the minimum cross section, at a 95% confidence level.
We report on a search for second generation leptoquarks LQ_2 which decay into a muon plus quark in p\bar{p} collisions at a center-of-mass energy of sqrt{s} = 1.96 TeV in the D0 detector using an integrated luminosity of about 300 pb-1. No evidence for a leptoquark signal is observed and an upper bound on the product of the cross section for single leptoquark production times branching fraction beta into a quark and a muon was determined for second generation scalar leptoquarks as a function of the leptoquark mass. This result has been combined with a previously published D0 search for leptoqu…
We report on a search for second generation leptoquarks (LQ) produced in $p\bar{p}$ collisions at sqrt{s} = 1.8 TeV using the D0 detector at Fermilab. Second generation leptoquarks are assumed to be produced in pairs and to decay to either μor νand either a strange or a charm quark (q). Limits are placed on σ(p-pbar -> LQ-LQbar -> μν+ jets) as a function of the mass of the leptoquark. For equal branching ratios to μq and νq, second generation scalar leptoquarks with a mass below 160 GeV/c^2, vector leptoquarks with anomalous minimal vector couplings with a mass below 240 GeV/c^2, and vector le…
We present the preliminary results of a search for leptoquark ($LQ$) pairs using (85.2 $\pm$ 3.7) pb$^{-1}$ of $p{\bar p}$ collider data collected by the DO experiment at the Fermilab Tevatron from 1994-1996. We observe no evidence for leptoquark production and set a limit on $σ(p{\bar p} \to LQ\bar{LQ} \to νν+ jets)$ as a function of the mass of the leptoquark ($M_{LQ}$), assuming BR($LQ \to νq$)=100%. At the 95% confidence level, we exclude scalar leptoquarks for $M_{LQ} < 99 GeV/c^2$, and vector leptoquarks for $M_{LQ} < 178 GeV/c^2$.
We report on a search for the pair production of scalar leptoquarks, $LQ$, using 191 pb$^{-1}$ of proton-antiproton collision data recorded by the CDF experiment during Run II of the Tevatron. The leptoquarks are sought via their decay into a neutrino and quark yielding missing transverse energy and several jets of large transverse energy. No evidence for leptoquark production is observed, and limits are set on $σ(p\bar p\to LQ\bar{LQ} X \to ν\barνq\bar q X)$. Using a next-to-leading order theoretical prediction of the cross section for scalar leptoquark production, we exclude first-generation…
We have searched for the pair production of first generation scalar leptoquarks in the eejj channel using the full data set (123 pb-1) collected with the D0 detector at the Fermilab Tevatron during 1992--1996. We observe no candidates with an expected background of approximately 0.4 events. Comparing the experimental 95% confidence level upper limit to theoretical calculations of the cross section with the assumption of a 100% branching fraction to eq, we set a lower limit on the mass of a first generation scalar leptoquark of 225 GeV/c^2. The results of this analysis rule out the interpretati…
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-$p_{\mathrm{T}}$ large-radius jet. The full Run 2 dataset is exploited, consisting of 139 fb$^{-1}$ of data collected from proton-proto…
A search for new-physics resonances decaying into a lepton and a jet performed by the ATLAS experiment is presented. Scalar leptoquarks pair-produced in $pp$ collisions at $\sqrt{s}=13$ TeV at the Large Hadron Collider are considered using an integrated luminosity of 139 fb$^{-1}$, corresponding to the full Run 2 dataset. They are searched for in events with two electrons or two muons and two or more jets, including jets identified as arising from the fragmentation of $c$- or $b$-quarks. The observed yield in each channel is consistent with the Standard Model background expectation. Leptoquark…
A search for pair production of third-generation scalar leptoquarks decaying to top quark and tau lepton pairs is presented using proton-proton collision data at a center-of-mass energy of sqrt(s) = 8 TeV collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 inverse femtobarns. The search is performed using events that contain an electron or a muon, a hadronically decaying tau lepton, and two or more jets. The observations are found to be consistent with the standard model predictions. Assuming that all leptoquarks decay to a top quark and a tau lepto…
Search for a leptoquark in events with a hadronically decaying $τ$-lepton and missing transverse momentum using $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
EUROPEAN ORGANISATION FOR NUCLEAR RESEARCH (CERN)（欧洲核子研究中心（CERN））
Search for pair-produced scalar and vector leptoquarks decaying into third-generation quarks and first- or second-generation leptons in pp collisions with the ATLAS detector
本研究利用LHC Run 2的139 fb⁻¹质子-质子碰撞数据，通过ATLAS探测器搜寻成对产生的多类轻夸克，未发现偏离标准模型的信号，给出了截面上限与质量下限，为解释B物理反常的两类模型设定了质量约束。
A search for pair production of third-generation scalar leptoquarks decaying into a top quark and a $τ$-lepton is presented. The search is based on a dataset of $pp$ collisions at $\sqrt{s}=13$ TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb$^{-1}$. Events are selected if they have one light lepton (electron or muon) and at least one hadronically decaying $τ$-lepton, or at least two light leptons. In addition, two or more jets, at least one of which must be identified as containing $b$-hadrons, are required. Si…
A search for pair production of heavy scalar leptoquarks (LQs), each decaying into a top quark and a $τ$ lepton, is presented. The search considers final states with an electron or a muon, one or two $τ$ leptons that decayed to hadrons, and additional jets. The data were collected in 2016 in proton-proton collisions at $\sqrt{s}=$ 13 TeV with the CMS detector at the LHC, and correspond to an integrated luminosity of 35.9 fb$^{-1}$. No evidence for pair production of LQs is found. Assuming a branching fraction of unity for the decay LQ$ \to $t$τ$, upper limits on the production cross section ar…
A search for new particles has been conducted using events with two high transverse momentum (pt) tau leptons that decay hadronically, at least two high-pt jets, and missing transverse energy from the tau lepton decays. The analysis is performed using data from proton-proton collisions, collected by the CMS experiment in 2015 at sqrt(s) = 13 TeV, corresponding to an integrated luminosity of 2.1 inverse femtobarns. The results are interpreted in two physics models. The first model involves heavy right-handed neutrinos, N[l] (l = e, mu, tau), and right-handed charged bosons, W[R], arising in a l…
The results of a previous search by the CMS Collaboration for squarks and gluinos are reinterpreted to constrain models of leptoquark (LQ) production. The search considers jets in association with a transverse momentum imbalance, using the $M_\mathrm{T2}$ variable. The analysis uses proton-proton collision data at $\sqrt{s}=$ 13 TeV, recorded with the CMS detector at the LHC in 2016 and corresponding to an integrated luminosity of 35.9 fb$^{-1}$. Leptoquark pair production is considered with LQ decays to a neutrino and a top, bottom, or light quark. This reinterpretation considers higher mass …
Search for leptoquark pair production decaying into $te^- \bar{t}e^+$ or $tμ^- \bar{t}μ^+$ in multi-lepton final states in $pp$ collisions at 13 TeV with the ATLAS detector
A search for charged Higgs bosons decaying into $W^\pm W^\pm$ or $W^\pm Z$ bosons is performed, involving experimental signatures with two leptons of the same charge, or three or four leptons with a variety of charge combinations, missing transverse momentum and jets. A data sample of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider between 2015 and 2018 is used. The data correspond to a total integrated luminosity of 139 fb$^{-1}$. The search is guided by a type-II seesaw model that extends the scalar sector of the Sta…
A search for pair production of third-generation scalar leptoquarks and supersymmetric top quark partners, top squarks, in final states involving tau leptons and bottom quarks is presented. The search uses events from a data sample of proton-proton collisions corresponding to an integrated luminosity of 19.7 inverse femtobarns, collected with the CMS detector at the LHC with sqrt(s) = 8 TeV. The number of observed events is found to be in agreement with the expected standard model background. Third-generation scalar leptoquarks with masses below 740 GeV are excluded at 95% confidence level, as…
A search for leptoquarks has been performed in 310 pb-1 of data from ppbar collisions at a center-of-mass energy of 1.96 TeV, collected by the D0 detector at the Fermilab Tevatron Collider. The topology analyzed consists of acoplanar jets with missing transverse energy. The data show good agreement with standard model expectations, and a lower mass limit of 136 GeV has been set at the 95% C.L. for a scalar leptoquark decaying exclusively into a quark and a neutrino.
A search for pair production of first and second generation leptoquarks is performed in final states containing either two charged leptons and two jets, or one charged lepton, one neutrino and two jets, using proton-proton collision data at sqrt(s) = 8 TeV. The data, corresponding to an integrated luminosity of 19.7 inverse femtobarns were recorded with the CMS detector at the LHC. First-generation scalar leptoquarks with masses less than 1010 (850) GeV are excluded for beta = 1.0 (0.5), where beta is the branching fraction of a leptoquark decaying to a charged lepton and a quark. Similarly, s…
The e^+ jet invariant mass spectrum produced in the reaction e^+ p -> e^+ X has been studied at a center-of-mass energy of 300 GeV. The data were collected using the ZEUS detector operating at the HERA collider, and correspond to an integrated luminosity of 47.7 pb^{-1}. The observed mass spectrum is in good agreement with Standard Model expectations up to an e^+ jet mass of 210 GeV. Above this mass, some excess is seen. The angular distribution of these events is typical of high-Q^2 neutral current events and does not give convincing evidence for the presence of a narrow scalar or vector stat…
Searches for pair-produced scalar leptoquarks are performed using 20 fb$^{-1}$ of proton-proton collision data provided by the LHC and recorded by the ATLAS detector at $\sqrt{s}=8$ TeV. Events with two electrons (muons) and two or more jets in the final state are used to search for first (second)-generation leptoquarks. The results from two previously published ATLAS analyses are interpreted in terms of third-generation leptoquarks decaying to $bν_τ\bar{b}\bar{ν_τ}$ and $tν_τ\bar{t}\bar{ν_τ}$ final states. No statistically significant excess above the Standard Model expectation is observed in…
We investigate the production of vector-like quarks with charge $5/3$ at the LHC and their subsequent decays into new singly or doubly charged bosons plus a heavy quark (top or bottom). In particular, we explore final states with same-sign di-leptons (electron or muon pairs), with the leptons coming from the decay of the new bosons and, in the case of production of singly charged bosons, from top quarks as well. These processes are predicted by classes of models based on extensions of the gauge group of the Standard Model, such as the 331 Model, where the electroweak symmetry is described by $…
A search for the pair production of first-generation scalar leptoquarks is performed using proton-proton collision data recorded at 13 TeV center-of-mass energy with the CMS detector at the LHC. The data correspond to an integrated luminosity of 35.9 fb$^{-1}$. The leptoquarks are assumed to decay to a quark, and either an electron or a neutrino with branching fractions $β$ and 1$-β$, respectively. The search targets the decay final states comprising two electrons, or one electron and large missing transverse momentum, along with two quarks that are detected as hadronic jets. First-generation …
A search for second and third generation scalar and vector leptoquarks produced in ep collisions via the lepton flavour violating processes ep -> mu X and ep -> tau X is performed by the H1 experiment at HERA. The full H1 ep data sample taken at a centre-of-mass energy of 319 GeV is used for the analysis. No evidence for the production of such leptoquarks is observed in the H1 data. Leptoquarks produced in ep collisions with a coupling strength of 0.3 and decaying with the same coupling strength to a muon-quark pair or a tau-quark pair are excluded at 95% confidence level up to leptoquark mass…
A search for second and third generation scalar and vector leptoquarks produced in ep collisions via the lepton flavour violating processes ep -> mu X and ep -> tau X is performed by the H1 experiment at HERA. The full data sample taken at a centre-of-mass energy sqrt{s} = 319 GeV is used for the analysis, corresponding to an integrated luminosity of 245 pb^-1 of e^+ p and 166 pb^-1 of e^- p collision data. No evidence for the production of such leptoquarks is observed in the H1 data. Leptoquarks produced in e^+- p collisions with a coupling strength of lambda=0.3 and decaying with the same co…
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…
Many models beyond the standard model predict the existence of vector-like quarks or other types of heavy resonances. Using proton-proton collision data at center-of-mass energies of 8 and 13 TeV, the ATLAS and CMS Collaborations have performed a multitude of searches for pair and singly produced vector-like quarks decaying to W, Z, or Higgs bosons. Heavy gauge and (pseudo)scalar resonances decaying to top quarks have been searched for as well. No evidence for any of these hypothetical particles has been found yet, and stringent exclusion limits are derived on their masses, cross sections and …
A search is performed for third-generation scalar leptoquarks and heavy right-handed neutrinos in events containing one electron or muon, one hadronically decaying tau lepton, and at least two jets, using a sqrt(s) = 13 TeV pp collision data sample corresponding to an integrated luminosity of 12.9 inverse femtobarns collected with the CMS detector at the LHC in 2016. The number of observed events is found to be in agreement with the standard model prediction. A limit is set at 95% confidence level on the product of the leptoquark pair production cross section and beta squared where beta is the…
We search for pair production of supersymmetric top quarks (~t_1), followed by R-parity violating decay ~t_1 -> tau b with a branching ratio beta, using 322 pb^-1 of ppbar collisions at sqrt{s}=1.96 TeV collected by the CDF II detector at Fermilab. Two candidate events pass our final selection criteria, consistent with the standard model expectation. We set upper limits on the cross section sigma(~t_1 ~tbar_1)*beta^2 as a function of the stop mass m(~t_1). Assuming beta=1, we set a 95% confidence level limit m(~t_1)>153 GeV/c^2. The limits are also applicable to the case of a third generation …
A search for second and third generation scalar and vector leptoquarks produced in ep collisions via the lepton flavour violating processes ep to mu-X and ep to tau-X is performed by the H1 Collaboration at HERA. The full H1 ep data sample taken at a centre-of-mass energy of 319 GeV is used for the analysis, corresponding to an integrated luminosity of 411 pb^-1. No evidence for the production of such leptoquarks is observed in the H1 data. Leptoquarks produced in ep collisions with a coupling strength of lambda=0.3 and decaying with the same coupling strength to a muon-quark pair or a tau-qua…
Search for excited $τ$-leptons and leptoquarks in the final state with $τ$-leptons and jets in pp collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector
CP violation from physics beyond the Standard Model is investigated in $B_{l4}$ decays: $B\to Dπl\barν_l$. In the decay process, we include various excited states as intermediate states decaying to the final hadrons, $D+π$. We consider the semileptonic decay to a tau lepton family as well. The CP violation is implemented through complex scalar--fermion couplings in the multi-Higgs doublet model and scalar-leptoquark models beyond the Standard Model. With these complex couplings, we calculate the CP-odd rate asymmetry and the optimal asymmetry. We find that for $B_{τ4}$ decays the optimal asymm…
Three of the most significant measured deviations from standard model predictions, the enhanced decay rate for B $\to$ D$^{(*)}τν$, hints of lepton universality violation in B $\to$ K$^{(*)}\ell\ell$ decays, and the anomalous magnetic moment of the muon, can be explained by the existence of leptoquarks (LQs) with large couplings to third-generation quarks and masses at the TeV scale. The existence of these states can be probed at the LHC in high energy proton-proton collisions. A novel search is presented for pair production of LQs coupled to a top quark and a muon using data at a center-of-ma…
We investigate the standard model (SM) with the extension of a charged scalar having fractional electromagnetic charge of $-1/3$ unit and with lepton and baryon number violating couplings at tree level. Without directly taking part in the electro-weak (EW) symmetry breaking, this scalar can affect stability of the EW vacuum via loop effects. The impact of such a scalar, i.e., a leptoquark on the perturbativity of SM dimensionless couplings as well as on new physics couplings has been studied at two-loop order. The vacuum stability of the Higgs potential is checked using one-loop renormalizatio…
A search for the lepton flavour violating processes ep->mu X and ep -> tau X is performed with the H1 experiment at HERA. Final states with a muon or tau and a hadronic jet are searched for in a data sample corresponding to an integrated luminosity of 66.5 pb-1 for e^+ p collisions and 13.7 pb^-1 for e^- p collisions at a centre-of-mass energy of 319 GeV. No evidence for lepton flavour violation is found. Limits are derived on the mass and the couplings of leptoquarks inducing lepton flavour violation in an extension of the Buchm"uller-R"uckl-Wyler effective model. Leptoquarks produced in ep c…
A search for new phenomena in final states with hadronically decaying tau leptons, $b$-jets, and missing transverse momentum is presented. The analyzed dataset comprises $pp$~collision data at a center-of-mass energy of $\sqrt s = 13$ TeV with an integrated luminosity of 139/fb, delivered by the Large Hadron Collider and recorded with the ATLAS detector from 2015 to 2018. The observed data are compatible with the expected Standard Model background. The results are interpreted in simplified models for two different scenarios. The first model is based on supersymmetry and considers pair producti…
A search is presented for a singly produced excited bottom quark (b*) decaying to a top quark and a W boson in the all-hadronic, lepton + jets, and dilepton final states in proton-proton collisions at sqrt(s) = 8 TeV recorded by the CMS experiment at the CERN LHC. Data corresponding to an integrated luminosity of 19.7 inverse femtobarns are used. No significant excess of events is observed with respect to standard model expectations. We set limits at 95% confidence on the product of the b* quark production cross section and its branching fraction to tW. The cross section limits are interpreted…
Search strategies for the third-generation leptoquarks (LQs) are distinct from other LQ searches, especially when they decay to a top quark and a $τ$ lepton. We investigate the cases of all TeV-scale scalar and vector LQs that decay to either a top-tau pair (charge-$1/3$ and $5/3$ LQs) or a top-neutrino pair (charge-$2/3$ LQs). One can then use the boosted top (which can be tagged efficiently using jet-substructure techniques) and high-$p_{\rm T}$ $τ$ leptons to search for these LQs. We consider two search channels with either one or two taus along with at least one hadronically decaying boost…
This search, a type not previously performed at ATLAS, uses a comparison of the production cross sections for $e^+ μ^-$ and $e^- μ^+$ pairs to constrain physics processes beyond the Standard Model. It uses $139 \text{fb}^{-1}$ of proton$-$proton collision data recorded at $\sqrt{s} = 13$ TeV at the LHC. Targeting sources of new physics which prefer final states containing $e^{+}μ^{-}$ to $e^{-}μ^{+}$, the search contains two broad signal regions which are used to provide model-independent constraints on the ratio of cross sections at the 2% level. The search also has two special selections tar…
A search for single production of vector-like top quark partners (T) decaying into a Higgs boson and a top quark is performed using data from pp collisions at a centre-of-mass energy of 13 TeV collected by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 2.3 inverse femtobarns. The top quark decay includes an electron or a muon while the Higgs boson decays into a pair of b quarks. No significant excess over standard model backgrounds is observed. Exclusion limits on the product of the production cross section and the branching fraction are derived in the T quark…
Two-Stage Machine Learning Strategy for Scalar and Vector Leptoquark Discrimination at the LHC
Universidad Autónoma de Madrid（马德里自治大学）；Centro Atómico Bariloche, Instituto Balseiro and CONICET（巴里洛切原子中心巴尔塞罗研究所与阿根廷国家科学研究委员会）；IFLP, CONICET - Dpto. de Física, Universidad Nacional de La Plata（拉普拉塔国立大学物理系与阿根廷国家科学研究委员会拉普拉塔理论物理研究所）
A search for excited electrons produced in $pp$ collisions at $\sqrt{s} = 13$ TeV via a contact interaction $q\bar{q} \to ee^*$ is presented. The search uses 36.1 fb$^{-1}$ of data collected in 2015 and 2016 by the ATLAS experiment at the Large Hadron Collider. Decays of the excited electron via a contact interaction into an electron and a pair of quarks ($eq\bar{q}$) are targeted in final states with two electrons and two hadronic jets, and decays via a gauge interaction into a neutrino and a $W$ boson ($νW$) are probed in final states with an electron, missing transverse momentum, and a larg…
A search is presented for a heavy vector-like quark, decaying into a b quark and a W boson, which is produced singly in association with a light flavor quark and a b quark. The analysis is performed using a data sample of proton-proton collisions at a center-of-mass energy of sqrt(s) = 13 TeV collected at the LHC in 2015. The data set used in the analysis corresponds to an integrated luminosity of 2.3 inverse femtobarns. The search is carried out using events containing one electron or muon, at least one b-tagged jet with large transverse momentum, at least one jet in the forward region of the…
A search for singly produced vector-like $T/Y$ quark is performed in proton-proton collision data at a centre-of-mass energy of $13$ TeV corresponding to an integrated luminosity of $139.1 fb^{-1}$, recorded with the ATLAS detector at the LHC from 2015-18. The analysis focused on the hadronic channel of $T/Y \rightarrow Wb$ decay mode. The hadronic channel is not a clean channel, unlike the leptonic channel, because of the contribution coming from the QCD processes, which accounts for a significant background. The modelling of QCD processes is challenging due to their theoretical prediction an…
Search for supersymmetry in final states with missing transverse momentum and charm-tagged jets using 139 fb$^{-1}$ of proton-proton collisions at $\sqrt{s}=$ 13 TeV with the ATLAS detector
A search for singly produced vector-like $Q$ quarks, where $Q$ can be either a $T$ quark with charge $+2/3$ or a $Y$ quark with charge $-4/3$, is performed in proton-proton collisions recorded with the ATLAS detector at the LHC. The dataset corresponds to an integrated luminosity of 20.3 fb$^{-1}$ and was produced with a centre-of-mass energy of $\sqrt{s}=8$ TeV. This analysis targets $Q \to Wb$ decays where the $W$ boson decays leptonically. A veto on massive large-radius jets is used to reject the dominant $t\bar{t}$ background. The reconstructed $Q$-candidate mass, ranging from 0.4 to 1.2 T…
We consider the contributions of individual new particles to the anomalous magnetic moment of the muon, utilizing the generic framework of simplified models. We also present analytic results for all possible one-loop contributions, allowing easy application of these results for more complete models which predict more than one particle capable of correcting the muon magnetic moment. Additionally, we provide a Mathematica code to allow the reader straightforwardly compute any 1-loop contribution. Furthermore, we derive bounds on each new particle considered, assuming either the absence of other …
A search is presented for new particles produced at the LHC in proton-proton collisions at $\sqrt{s} =$ 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb$^{-1}$, collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search base…
A search for singly produced vector-like quarks $Q$, where $Q$ can be either a $T$ quark with charge $+2/3$ or a $Y$ quark with charge $-4/3$, is performed in proton-proton collision data at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of $36.1 \text{fb}^{-1}$, recorded with the ATLAS detector at the LHC in 2015 and 2016. The analysis targets $Q \to Wb$ decays where the $W$ boson decays leptonically. No significant deviation from the expected Standard Model background is observed. Upper limits are set on the $QWb$ coupling strength and the mixing between the Stan…
Search for singly produced vector-like top partners in multilepton final states with 139 $\mathrm{fb}^{-1}$ of $pp$ collision data at $\sqrt{s} = 13$ TeV with the ATLAS detector
