7 research outputs found
Improving the Composition of Ultra High Energy Cosmic Rays with Ground Detector Data
We show that the maximum shower depth distributions of Ultra-High Energy
Cosmic Rays (UHECRs), as measured by fluorescence telescopes, can be augmented
by building a mapping to observables collected by surface detectors. The
resulting statistical improvement of such augmented dataset depends in a
universal way on the strength of the correlation exhibited by the mapping.
Building upon the publicly available data on "golden hybrid" events from the
Pierre Auger Observatory we project possible improvements in the inferred
composition of UHECRs for a range of possible mappings with varying correlation
strengths.Comment: 8 pages, 6 figures, method correcte
Bump Hunting in Latent Space
Unsupervised anomaly detection could be crucial in future analyses searching
for rare phenomena in large datasets, as for example collected at the LHC. To
this end, we introduce a physics inspired variational autoencoder (VAE)
architecture which performs competitively and robustly on the LHC Olympics
Machine Learning Challenge datasets. We demonstrate how embedding some physical
observables directly into the VAE latent space, while at the same time keeping
the classifier manifestly agnostic to them, can help to identify and
characterise features in measured spectra as caused by the presence of
anomalies in a dataset.Comment: 5 pages, 4 figure
Rare decay in the framework of the Standard Model with additional chiral right-handed neutrinos.
V magistrskem delu preučujemo razpad , pri katerem mezon razpade v dva nevtrina in morebiten nizkoenergijski foton (foton je neopazljiv), in razpad , pri katerem je foton opazljiv, v okviru razširjenega standardnega modela z dodatnimi desnoročnimi nevtrini. V tem modelu so nevtrini v masni bazi Majoranovi fermioni. Matrične elemente matrik nevtrinskega sektorja izrazimo z na novo izpeljano parametrizacijo, ki je naravna posplošitev parametrizacije Casas-Ibara. Diferencialni razpadni širini razpadov in pa analitično izpeljemo v razširjenemu standardnemu modelu za splošen . Pri obravnavi odvisnosti razvejitvenih razmerij razpadov in predpostavimo, da detektor pokriva celotni prostorski kot glede na točko razpada mezona . Na koncu pa komentiramo še primer, ko ta ne pokriva celotnega prostorskega kota. V slednjem se izkaže, da je prispevek razpada k pogostosti razpadov mezona v neopazljive končne produkte lahko popolnoma zanemarljiv. Predstavljene ugotovitve veljajo kvalitativno tudi za razpade drugih okusnih nevtralnih mezonov v osnovnem stanju v dva nevtrina in morebiten (nizkoenergijski) foton.In this master thesis, we study the decay, where meson decays into two neutrinos and a potential soft photon, and the decay with an observable photon in the framework of the Standard Model with additional chiral right-handed neutrinos. In this model neutrinos in the mass basis are Majorana fermions. We parametrize the mass matrices in the neutrino sector with a newly derived parametrization which naturally generalizes the well known Casas-Ibara parametrization. The differential decay widths of the and decay modes are derived for the general case (with additional neutrinos). The branching ratios of the and decays are investigated within the assumption that the photon detectors cover the full solid angle around the decay point of the meson. The more general case is commented on at the end of the thesis: we find that the contribution of the decay to meson decays with non-observable decay products can be completely negligible. The results presented in this work qualitatively apply also to other decays of pseudoscalar neutral flavored mesons to two neutrinos and a potential (soft) photon
Light Majorana neutrinos in (semi)invisible meson decays
We reconsider decays of pseudoscalar mesons (P) to neutrino pairs and possibly additional photons in presence of (light) Majorana neutrinos. For this purpose we derive a model-independent general parametrization of neutrino mass matrices with physically interpretable and irreducible set of parameters. The parametrization is valid for any number of neutrinos and interpolates smoothly between the heavy Majorana and the (pseudo)Dirac neutrino limits. We apply the new parametrization to the study of and decays within the SM extended by additional singlet fermions. We update the SM predictions for the branching ratios of and discuss the sensitivity of the decays to neutrino mass and mixing parameters
Optimized Probes of the CP Nature of the Top Quark Yukawa Coupling at Hadron Colliders
We summarize our recent proposals for probing the CP-odd iκ˜t¯γ5th interaction at the LHC and its projected upgrades directly using associated on-shell Higgs boson and top quark or top quark pair production. We first recount how to construct a CP-odd observable based on top quark polarization in Wb→th scattering with optimal linear sensitivity to κ˜. For the corresponding hadronic process pp→thj we then present a method of extracting the phase-space dependent weight function that allows to retain close to optimal sensitivity to κ˜. For the case of top quark pair production in association with the Higgs boson, pp→tt¯h, with semileptonically decaying tops, we instead show how one can construct manifestly CP-odd observables that rely solely on measuring the momenta of the Higgs boson and the leptons and b-jets from the decaying tops without having to distinguish the charge of the b-jets. Finally, we introduce machine learning (ML) and non-ML techniques to study the phase-space optimization of such CP-odd observables. We emphasize a simple optimized linear combination α⋅ω that gives similar sensitivity as the studied fully fledged ML models. Using α⋅ω we review sensitivity projections to κ˜ at HL-LHC, HE-LHC, and FCC-hh
Optimized Probes of the CP Nature of the Top Quark Yukawa Coupling at Hadron Colliders
We summarize our recent proposals for probing the CP-odd iκ˜t¯γ5th interaction at the LHC and its projected upgrades directly using associated on-shell Higgs boson and top quark or top quark pair production. We first recount how to construct a CP-odd observable based on top quark polarization in Wb→th scattering with optimal linear sensitivity to κ˜. For the corresponding hadronic process pp→thj we then present a method of extracting the phase-space dependent weight function that allows to retain close to optimal sensitivity to κ˜. For the case of top quark pair production in association with the Higgs boson, pp→tt¯h, with semileptonically decaying tops, we instead show how one can construct manifestly CP-odd observables that rely solely on measuring the momenta of the Higgs boson and the leptons and b-jets from the decaying tops without having to distinguish the charge of the b-jets. Finally, we introduce machine learning (ML) and non-ML techniques to study the phase-space optimization of such CP-odd observables. We emphasize a simple optimized linear combination α·ω that gives similar sensitivity as the studied fully fledged ML models. Using α·ω we review sensitivity projections to κ˜ at HL-LHC, HE-LHC, and FCC-hh