AMPLITUDE ANALYSIS AND POLARISATION MEASUREMENT OF THE LAMBDAC BARYON IN PKPI FINAL STATE FOR ELECTROMAGNETIC DIPOLE MOMENT EXPERIMENT
Tesi di Dottorato
Data di Pubblicazione:
2020
Citazione:
AMPLITUDE ANALYSIS AND POLARISATION MEASUREMENT OF THE LAMBDAC BARYON IN PKPI FINAL STATE FOR ELECTROMAGNETIC DIPOLE MOMENT EXPERIMENT / D. Marangotto ; supervisore: N. Neri ; coordinatore: M. Paris. Dipartimento di Fisica Aldo Pontremoli, 2020 Mar 16. 32. ciclo, Anno Accademico 2019. [10.13130/marangotto-daniele_phd2020-03-16].
Abstract:
The first part of the thesis presents an experiment proposal for short-lived
heavy baryon electromagnetic dipole moments measurement, exploiting
spin precession of particles channeled in bent crystals, produced from
fixed-target collisions of multi-TeV energy protons extracted from the
main beam of the Large Hadron Collider accelerator. The LHCb detector is
considered to measure the baryon polarisation from its decay distribution.
The same methodology is further extended to the measurement of τ
lepton electromagnetic dipole moments, which is complicated by the
presence of undetectable neutrinos.
The second part of the thesis presents the amplitude analysis of Λc → pKπ
decays from Λb → Λc μ X production recorded by the LHCb experiment,
including the extraction of the Λc polarisation vector. This analysis is an
essential tool in light of the Λc baryon dipole moments measurement,
providing an unprecedented knowledge of the main Λc decay mode and
the Λc polarisation. Order one million events are selected from LHCb data
with negligible background contributions. The Λc → pKπ decay model for
generic polarisation is written in the helicity formalism and fitted to data.
An amplitude model describing Λc → pKπ decays has been obtained from
two-dimensional Dalitz plot fits, giving valuable information on the main
intermediate resonances, including the observation of new Λ* resonant
contributions.
The third part of the thesis deals with the Λc polarisation measurement in
proton-neon collisions at 68.6 GeV centre-of-mass energy recorded by
LHCb, which provides information on the Λc baryon structure. A significant
Λc polarisation is also crucial for the proposed dipole moments
experiment. The feasibility of the measurement has been proved
achieving two essential results: a few hundreds Λc → pKπ decays are
selected from proton-neon LHCb data, separated from background
contributions; the Λc polarisation measurement from the selected sample
has been proved feasible on simulated pseudo-experiments, showing that
the main associated systematic uncertainty is negligible compared to
statistical fluctuations.
Tipologia IRIS:
Tesi di dottorato
Elenco autori:
D. Marangotto
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