Simplified fast detector simulation in MadAnalysis 5

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The measured branching fractions of B-mesons into leptonic final states derived by the LHCb, Belle and BaBar collaborations hint towards the breakdown of lepton flavour universality. In this work we take at face value the so-called $$ {R}_{D^{\left(\ast \right)}} $$ R D ∗ observables that are defined as the ratios of neutral B-meson charged-current decays into a D(*)-meson, a charged lepton and a neutrino final state in the tau and light lepton channels. A well-studied and simple solution to this charged current anomaly is to introduce a scalar leptoquark S1 that couples to the second and third generation of fermions. We investigate how S1 can also serve as a mediator between the Standard Model and a dark sector. We study this scenario in detail and estimate the constraints arising from collider searches for leptoquarks, collider searches for missing energy signals, direct detection experiments and the dark matter relic abundance. We stress that the production of a pair of leptoquarks that decays into different final states (i.e. the commonly called “mixed” channels) provides critical information for identifying the underlying dynamics, and we exemplify this by studying the tτbν and the resonant S1 plus missing energy channels. We find that direct detection data provides non-negligible constraints on the leptoquark coupling to the dark sector, which in turn affects the relic abundance. We also show that the correct relic abundance can not only arise via standard freeze-out, but also through conversion-driven freeze-out. We illustrate the rich phenomenology of the model with a few selected benchmark points, providing a broad stroke of the interesting connection between lepton flavour universality violation and dark matter.

Section: C4 Cms Soft-lepton(s) Plus Metmentioning

confidence: 99%

Leptoquark manoeuvres in the dark: a simultaneous solution of the dark matter problem and the $$ {R}_{D^{\left(\ast \right)}} $$ anomalies

Bélanger

Bharucha

Fuks

et al. 2022

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“…Pythia 8 is also used to simulate parton showering, as well as hadronisation. The reconstruction of the objects in the final state is done through MadAnalysis 5[79][80][81], using the anti-k T algorithm[82] with radius parameter R = 0.4 as implemented in FastJet[83].…”

mentioning

confidence: 99%

Single production of vector-like quarks: the effects of large width, interference and NLO corrections

Deandrea

Flacke

Fuks

et al. 2021

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We provide a comprehensive discussion, together with a complete setup for simulations, relevant for the production of a single vector-like quark at hadron colliders. Our predictions include finite width effects, signal-background interference effects and next-to-leading order QCD corrections. We explicitly apply the framework to study the single production of a vector-like quark T with charge 2/3, but the same procedure can be used to analyse the single production of vector-like quarks with charge −4/3, −1/3, 2/3 and 5/3, when the vector-like quark interacts with the Standard Model quarks and electroweak bosons. Moreover, this procedure can be straightforwardly extended to include additional interactions with exotic particles. We provide quantitative results for representative benchmark scenarios characterised by the T mass and width, and we determine the role of the interference terms for a range of masses and widths of phenomenological significance. We additionally describe in detail, both analytically and numerically, a striking feature in the invariant mass distribution appearing only in the T → th channel.

“…We are grateful to Céline Degrande for technical assistance with FeynRules and NloCT. We are in debt to several of the many excellent analyses [62,114,115] on the MadAnalysis 5 Public Analysis Database (PAD) [100], which we used as guides while developing our own reimplementations.…”

Section: Acknowledgmentsmentioning

confidence: 99%

$$ t\overline{t}t\overline{t} $$ signatures through the lens of color-octet scalars

Carpenter

Murphy

Smylie

2022

We reinterpret two recent LHC searches for events containing four top quarks $$ \left(t\overline{t}t\overline{t}\right) $$ t t ¯ t t ¯ in the context of supersymmetric models with Dirac gauginos and color-octet scalars (sgluons). We explore whether sgluon contributions to the four-top production cross section $$ \sigma \left( pp\to t\overline{t}t\overline{t}\right) $$ σ pp → t t ¯ t t ¯ can accommodate an excess of four-top events recently reported by the ATLAS collaboration. We also study constraints on these models from an ATLAS search for new phenomena with high jet multiplicity and significant missing transverse energy $$ \left({E}_{\mathrm{T}}^{\mathrm{miss}}\right) $$ E T miss sensitive to signals with four top quarks. We find that these two analyses provide complementary constraints, with the jets + $$ {E}_{\mathrm{T}}^{\mathrm{miss}} $$ E T miss search exceeding the four-top cross section measurement in sensitivity for sgluons heavier than about 800 GeV. We ultimately find that either a scalar or a pseudoscalar sgluon can currently fit the ATLAS excess in a range of reasonable benchmark scenarios, though a pseudoscalar in minimal Dirac gaugino models is ruled out. We finally offer sensitivity projections for these analyses at the HL-LHC, mapping the 5σ discovery potential in sgluon parameter space and computing exclusion limits at 95% CL in scenarios where no excess is found.