arXiv subjects

Jelle Groot

Publications and source records attributed to Jelle Groot.

4 recordsLinked to original sources

arXiv2026

CP violation in $B_{(s)}\toϕK$ decays: Standard Model and isospin-dependent New Physics

The penguin-dominated $B\toϕK$ decays provide sensitive probes of physics beyond the Standard Model. Interpreting them at increasing experimental precision requires control of doubly Cabibbo-suppressed hadronic contributions. Using a factorization approach, we obtain Standard Model benchmarks for the branching ratios and CP-violating observables, including the hadronic phase shift in $B_d^0\toϕK_{\rm S}$. The $B_s^0\toϕK_{\rm S}$ channel, in which the corresponding penguin effects are not Cabibbo-suppressed, offers additional insight into these contributions. Comparing the neutral and charged $B\toϕK$ modes further allows the construction of isospin observables. We discuss their Standard-Model expectations and sensitivity to New Physics in the $I=0$ and $I=1$ sectors. The available data are consistent with the Standard Model, while leaving substantial room for New Physics contributions.

hep-ph↗

arXiv2026

CP Violation in $B_{(s)}\toϕK$ Decays: Standard Model Benchmarks and Isospin-Breaking New Physics

The penguin loop-suppressed $B\toϕK$ decays are highly sensitive to contributions of hypothetical heavy new particles. Particularly interesting probes for testing the Standard Model and revealing such phenomena are provided by CP violation in the $B^0_d\toϕK_{\rm S}$ decay. Standard-Model estimates for the corresponding CP-violating observables are theoretically limited by doubly Cabibbo-suppressed penguin contributions. We study these effects using a factorization approach, and provide predictions for CP asymmetries, to be contrasted with future measurements. To gain additional insight into these hadronic effects, we propose the $B_s^0\toϕK_{\rm S}$ decay as a new channel. We predict the observables for this decay for which currently no measurements exist. By comparing $B^0_d\toϕK_{\rm S}$ and $B^+ \to ϕK^+$, we further derive state-of-the-art constraints on isospin observables within the Standard Model. The same framework enables probing of possible New-Physics contributions, including general effects and those with non-trivial isospin structure. Interesting prospects arise for the high-precision era of flavour physics ahead.

hep-ph↗

arXiv2026

Big Bang Nucleosynthesis and the Neutrino-Extended Standard Model Effective Field Theory

We study the impact of light GeV-scale heavy neutral leptons (HNLs) on Big Bang nucleosynthesis (BBN) in the neutrino-extended Standard Model Effective Field Theory ($ν$SMEFT). We show that, based on very general considerations, BBN constraints complement laboratory searches at colliders, beam dumps, and neutrinoless double beta decay, by providing an upper bound on the cut-off scale of the effective field theory for HNL masses above $\sim$100 MeV. We identify target regions for future laboratory probes of the $ν$SMEFT parameter space that is bounded from above and below.

hep-ph↗

arXiv2025

Probing light sterile neutrinos in left-right symmetric models with displaced vertices and neutrinoless double beta decay

An investigation of relatively light (GeV-scale), long-lived right-handed neutrinos is performed within minimal left-right symmetric models using the neutrino-extended Standard Model Effective Field Theory framework. Light sterile neutrinos can be produced through rare decays of kaons, $D$-mesons, and $B$-mesons at the Large Hadron Collider (LHC) and the Long-Baseline Neutrino Facility (LBNF) of Fermilab. Their decays could result in displaced vertices, which can be reconstructed. By performing Monte-Carlo simulations, we assess the sensitivities of the future LHC far-detector experiments ANUBIS, CODEX-b, FACET, FASER(2), MoEDAL-MAPP1(2), MATHUSLA, the recently approved beam-dump experiment SHiP, and the upcoming neutrino experiment DUNE at the LBNF, to the right-handed gauge-boson mass $M_{W_R}$ as functions of neutrino masses. We find that DUNE and SHiP could be sensitive to right-handed gauge-boson masses up to $\sim 25$ TeV. We compare this reach to indirect searches such as neutrinoless double beta decay, finding that displaced-vertex searches are very competitive.

hep-ph↗