arXiv subjects

Robert Kowalewski

Publications and source records attributed to Robert Kowalewski.

3 recordsLinked to original sources

arXiv2026

Mapping quark-level kinematics to hadrons in a new hybrid model of semileptonic $B$ meson decays

The need to map parton-level processes to color-neutral hadrons in a way that respects quark-hadron duality arises in several areas of physics, including in the semileptonic decays of $B$ mesons. Integrated over large regions of phase space, the quark-level and hadron-level quantities are expected to be equal. However, the breakdown of duality is manifest at low hadron-system invariant masses, where discrete resonances dominate. In practice, this means independent simulations of decays to low-lying resonances and to higher-mass hadronic systems must be merged into a coherent model. We present a novel method to combine these resonant and non-resonant components in simulations of inclusive $b \to u\ell\nu$ decays that uses an optimal transport algorithm. The method currently used in measurements of inclusive semileptonic $B$ decay branching fractions introduces unphysical features in kinematic spectra such as large discontinuities and negative yields. The optimal transport method solves both of these issues and can be easily implemented in experimental studies of $B \to X_u \ell \nu$ decays.

hep-ph↗

arXiv2017

A Challenge to Lepton Universality in B Meson Decays

One of the key assumptions of the Standard Model of fundamental particles is that the interactions of the charged leptons, namely electrons, muons, and taus, differ only because of their different masses. While precision tests comparing processes involving electrons and muons have not revealed any significant violation of this assumption, recent studies involving the higher-mass tau lepton have resulted in observations that challenge lepton universality at the level of four standard deviations. A confirmation of these results would point to new particles or interactions, and could have profound implications for our understanding of particle physics.

hep-ex↗

arXiv2004

Search for Dark Matter in b -> s Transitions with Missing Energy

Dedicated underground experiments searching for dark matter have little sensitivity to GeV and sub-GeV masses of dark matter particles. We show that the decay of B mesons to K(K^*) and missing energy in the final state can be an efficient probe of dark matter models in this mass range. We analyze the minimal scalar dark matter model to show that the width of the decay mode with two dark matter scalars B\to KSS may exceed the decay width in the Standard Model channel, B\to Kν\barν, by up to two orders of magnitude. Existing data from B physics experiments almost entirely exclude dark matter scalars with masses less than 1 GeV. Expected data from B factories will probe the range of dark matter masses up to 2 GeV.

hep-ph↗