621 documents found, page 1 of 63
Deep learning searches for vector-like leptons at the LHC and electron/muon col...
Morais, António P.; Onofre, António; Freitas, Felipe F.; Gonçalves, João; Pasechnik, Roman; Santos, Ruihe discovery potential of both singlet and doublet vector-like leptons (VLLs) at the Large Hadron Collider (LHC) as well as at the not-so-far future muon and electron machines is explored. The focus is on a single production channel for LHC direct searches while double production signatures are proposed for the leptonic colliders. A Deep Learning algorithm to determine the discovery (or exclusion) statistical s...
Exploring mixed lepton-quark interactions in non-resonant leptoquark production...
Gonçalves, João; Morais, António P.; Onofre, António; Pasechnik, RomanSearches for new physics (NP) at particle colliders typically involve multivariate analysis of kinematic distributions of final state particles produced in a decay of a hypothetical NP resonance. Since the pair-production cross-sections mediated by such resonances are strongly suppressed by the NP scale, this analysis becomes less relevant for NP searches for masses of the BSM resonance above 1 TeV. On the othe...
CP-violation, asymmetries and interferences in tt¯ϕ
Azevedo, Duarte; Capucha, Rodrigo; Onofre, António; Santos, RuiIn this paper, we use the associated production of top-quark pairs (tt¯) with a generic scalar boson (ϕ) at the LHC (pp → tt¯ϕ) to explore the sensitivity of a large set of observables to the sign of the CP mixing angle (α), present in the coupling between the scalar boson and the top quarks. The mass of the scalar boson is set to mϕ = 125 GeV (the Standard Model Higgs boson mass) and its coupling to top-quarks...
Collider phenomenology of new neutral scalars in a flavoured multi-Higgs model
Ferreira, Pedro M.; Gonçalves, João Pedro Pino; Morais, António P.; Onofre, António; Pasechnik, Roman; Vatellis, VasileiosIn this work, we propose and explore for the first time a new collider signature of heavy neutral scalars typically found in many distinct classes of multi-Higgs models. This signature, particular relevant in the context of the Large Hadron Collider (LHC) measurements, is based on a topology with two charged leptons and four jets arising from first and second generation quarks. As an important benchmark scenari...
Ultralight bosons for strong gravity applications from simple Standard Model ex...
Freitas, Felipe F.; Herdeiro, Carlos A.R.; Morais, António P.; Onofre, António; Pasechnik, Roman; Radu, Eugen; Sanchis-Gual, Nicolas; Santos, RuiWe construct families, and concrete examples, of simple extensions of the Standard Model that can yield ultralight real or complex vectors or scalars with potential astrophysical relevance. Specifically, the mass range for these putative fundamental bosons (∼ 10-10-10-20 eV) would lead dynamically to both new non-black hole compact objects (bosonic stars) and new non-Kerr black holes, with masses of ∼ M⊙to ∼ 10...
Search for long-lived charginos based on a disappearing-track signature in pp c...
ATLAS collaboration (2874 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Anjos, Nuno; Araque, Juan Pedro; Carvalho, JoãoThis paper presents a search for direct electroweak gaugino or gluino pair production with a chargino nearly mass-degenerate with a stable neutralino. It is based on an integrated luminosity of 36.1 fb$^{−1}$ of pp collisions at $ \sqrt{s}=13 $ TeV collected by the ATLAS experiment at the LHC. The final state of interest is a disappearing track accompanied by at least one jet with high transverse momentum from ...
Measurement of $\tau $ polarisation in $Z/\gamma ^{*}\rightarrow \tau \tau $ de...
ATLAS collaboration (2896 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Anjos, Nuno; Araque, Juan PedroThis paper presents a measurement of the polarisation of $\tau $ leptons produced in $Z/\gamma ^{*}\rightarrow \tau \tau $ decays which is performed with a dataset of proton—proton collisions at $\sqrt{s}=8$ TeV, corresponding to an integrated luminosity of 20.2 fb$^{-1}$ recorded with the ATLAS detector at the LHC in 2012. The $Z/\gamma ^{*}\rightarrow \tau \tau $ decays are reconstructed from a hadronically d...
Measurement of longitudinal flow decorrelations in Pb+Pb collisions at $\sqrt{s...
ATLAS collaboration (2902 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Anjos, Nuno; Araque, Juan PedroMeasurements of longitudinal flow decorrelations are presented for charged particles in the pseudorapidity range $|\eta|<2.4$ using 7 $\mu$b$^{-1}$ and 470 $\mu$b$^{-1}$ of Pb+Pb collisions at $\sqrt{s_{\textrm{NN}}}=2.76$ and 5.02 TeV, respectively, recorded by the ATLAS detector at the LHC. It is found that the correlation between the harmonic flow coefficients $v_n$ measured in two separated $\eta$ intervals...
Search for B-L R -parity-violating top squarks in $\sqrt s$ =13 TeV pp collisi...
ATLAS collaboration (2894 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Anjos, Nuno; Araque, Juan PedroA search is presented for the direct pair production of the stop, the supersymmetric partner of the top quark, that decays through an R-parity-violating coupling to a final state with two leptons and two jets, at least one of which is identified as a b-jet. The data set corresponds to an integrated luminosity of 36.1 fb-1 of proton-proton collisions at a center-of-mass energy of s=13 TeV, collected in 2015 an...
Search for the direct production of charginos and neutralinos in final states w...
ATLAS collaboration (2882 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Anjos, Nuno; Araque, Juan PedroA search for the direct production of charginos and neutralinos in final states with at least two hadronically decaying tau leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of 36.1 fb$^{-1}$ , recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 13 TeV. No significant deviation from the expected Standard Model bac...