arXiv subjects

N. A. Neill

Publications and source records attributed to N. A. Neill.

3 recordsLinked to original sources

arXiv2023

The $b$ quark fragmentation fractions at LHCb and meson decays with heavy quark spectators

We study the current estimates of $B_c\to B_s π$ to extract the fragmentation fraction $f_c/f_s$ at the LHCb. A rather robust estimate of $Br(B_c\to B_s π)$ based on factorization and lattice results for the form factor gives $f_c/f_s \sim 0.056$ with a $16\%$ error. We also revisit the extraction of $f_s/f_d$ using $B\to Dπ$ instead of the theoretical cleaner but more suppressed channel $B\to DK$. We also find a tension on the predictions of $Br(B_c\to J/ψπ)$ and $Br(B_c\to B_sπ)$ considering the measurements of these modes at LHCb, and find that, within a $23\%$ uncertainty, only the lower end of the current prediction range $Br(B_c\to J/ψ)\sim 0.4\% - 1.7\%$ would be consistent with the LHCb measurements.

hep-ph↗

arXiv2019

Searching for a Sterile Neutrino in Tau Decays at B-factories

The phenomenon of neutrino flavor oscillations motivates searches for sterile neutrinos in a broad range of masses and mixing-parameter values. A sterile neutrino $N$ that mixes predominantly with the $τ$ neutrino is particularly challenging experimentally. To address this challenge, we propose a new method to search for a $ν_τ$-mixing with $N$ lighter than the $τ$ lepton. The method uses the large $e^+e^-\toτ^+τ^-$ samples collected at $B$-factory experiments to produce the $N$ in $τ$-lepton decays. We exploit the long lifetime of a sterile neutrino in this mass range to suppress background and apply kinematic and vertexing constraints that enable measuring the sterile neutrino mass. Estimates for the sensitivities of the BaBar, Belle, and Belle~II experiments are calculated and presented.

hep-ph↗

arXiv2019

Exotic coloured fermions and lepton number violation at the LHC

Majorana neutrino mass models with a scale of lepton number violation (LNV) of order TeV potentially lead to signals at the LHC. Here, we consider an extension of the standard model with a coloured octet fermion and a scalar leptoquark. This model generates neutrino masses at 2-loop order. We make a detailed MonteCarlo study of the LNV signal at the LHC in this model, including a simulation of standard model backgrounds. Our forecast predicts that the LHC with 300/fb should be able to probe this model up to colour octet fermion masses in the range of (2.6-2.7) TeV, depending on the lepton flavour of the final state.

hep-ph↗