Tag: Particle physics theoretical and experimental studies
Next-to-leading power terms can be significant in slepton pair production
What the study found Next-to-leading power contributions in the threshold variable can be significant for inclusive slepton pair production. The authors also report that existing calculations underestimate the scale error for large slepton masses. Why the authors say this matters The study suggests that accounting for these next-to-leading power effects is important when assessing theoretical…
Semi-visible dark jets may be probed at FCC-ee
What the study found The study finds that Higgs-boson-mediated production of dark quarks at the Future Circular Collider in electron-positron collisions could produce semi-visible jets, meaning jets made of both visible and invisible particles. The authors report that a graph neural network jet tagger helps improve sensitivity, especially when the invisible part of the signal…
A4 symmetry gives best match in leptonic 3HDM
What the study found The study found that, in the three-Higgs-doublet model, assigning the Higgs doublets to transform as a flavor triplet under the A4 group reproduces the experimentally observed neutrino mixing angles with arbitrary precision. It also keeps the correct mass ordering for charged leptons and for neutral leptons, which are Dirac neutrinos with…
LHCb measurements match expectations for B+ decay angular rates
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What the study found The measured normalised decay rate of B+ → J/ψ(→ μ+ μ−)K+ as a function of the lepton helicity angle agrees with expectations. The study also reports that the LHCb Upgrade I detector response is understood to the precision needed for related measurements. Why the authors say this matters The authors conclude…
Modified PYTHIA mPDFs better satisfy symmetry and sum rules
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What the study found A modified algorithm based on PYTHIA produces equal-scale multi-parton distribution functions that are symmetric and satisfy the relevant sum rules more closely than earlier PYTHIA-based results. Why the authors say this matters The authors state that multi-parton distribution functions are important for predicting multiple scattering rates at hadron colliders, and the…
Transformer identifies heavily modified jets in heavy-ion collisions
What the study found The study found that a Transformer classifier can identify a class of jets in nucleus-nucleus collisions that have been unequivocally modified. It also found a robust estimate of the upper bound for the fraction of jets in nucleus-nucleus collisions that are indistinguishable from those produced in proton-proton collisions. Why the authors…
Method reduces uncertainty in precision two-body mass measurements
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What the study found The study found that detector-related uncertainties can be analyzed more rigorously by looking at how observed mass shifts depend on the sum and difference of the daughter particle momenta in two-body decays. The authors applied this idea to the Λ hyperon (a particle made of one up quark, one down quark,…
Bell nonlocality observed in tau-pair collisions at the LHC
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What the study found The study reports that tau-plus tau-minus pairs produced in proton-proton collisions at the Large Hadron Collider can be analyzed as an entangled two-qubit quantum state, and that Bell nonlocality was observed with high statistical significance. The authors say tau-plus tau-minus is an ideal system for quantum information studies in high-energy collisions.…
Neutral-kaon decays can show CP violation through experimental efficiency
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What the study found CP violation in the kaon system can appear in decays to final states that contain neutral kaons. The authors say the relevant efficiency can be split into a kaon-energy part and a detector-dependent part that does not depend on the decay process. Why the authors say this matters The study suggests…
Two-component dark matter shows enhanced self-resonant scattering
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What the study found The study presents a two-component scalar dark matter model in which both dark matter components are stable because of a remaining Z4 gauge symmetry, left over from a U(1)′ local symmetry. Under a resonance condition for the dark matter masses, the authors report enhanced elastic co-scattering between the two dark matter…
