© Florian Bernlochner

Prof. Dr. Florian Bernlochner

Welcome to the website of the working group of Prof. Dr. Florian Bernlochner.

The group is engaged in the study of properties of heavy beauty quarks. Beauty quark provide a unique telescope into the early universe: through their manifold decays, they allow the measurement of many fundamental parametres of the Standard Model of particle physics and the search for new physics phenomena. The research group is one of the leading places in the world in the experimental and phenomenological study of semileptonic and leptonic decays of beauty hadrons. This line of research we carry out with the japanese Belle and Belle II experiments. In addition, we are searching for feebly interacting particles (FIPs) with the FASER experiment at CERN.


Here are a few topics I am interested in and that my group is working on.



The ForwArd Search ExpeRiment (FASER) is a new, small experiment at the Large Hadron Collider (LHC). It was built to search for light, weakly interacting particles. These could be produced in high-energy proton-proton collisions and emitted in the extreme forward direction. Therefore, FASER is located 480 m behind the ATLAS detector in the beam direction. In addition, FASER consists of a special subdetector to detect neutrinos from LHC collisions.


Lepton Flavor Universality

In the Standard Model of Particle Physics there are three flavor generations of leptons and quarks. Particles from different generations are identical except for their masses. The strength of the weak interaction is assumed to be the same for all flavors in the leptonic sector of the Standard Model. This postulate is termed as Lepton Flavor Universality. Intriguingly, experimentally testing this postulation leads to a significant deviation when compariong heavy tau-lepton couplings to electrons and muons. More decays with tau-leptons seem to be there as predicted by the Standard Model! We are involved in new and more precise measurements to further probe this anomaly with the Belle and Belle II experiments. Further, we are also on the forefront to produce precision predictions of the Standard Model expectation on the observables we aim to measure. There are many speculations about the origion of the deviation and a confirmation will pave the way for the discovery of new particles such as leptoquarks or multiple Higgs bosons.

© Belle II

Machine Learning

A large variety of tasks, in different reconstruction stages, are carried out  by Machine Learning algorithms in the majority of modern High Energy Physics experiments. In Belle II we also profit from the advancements in certain subfields of Machine Learning. Our group is involved in the development, commission and calibration of algorithms to maximize the performance of the Belle II detector. For instance, we are leading the effort on the multivariate reconstruction of beauty hadrons. 

© Florian Bernlochner

Precision Measurements of CKM Matrix Elements

In the Standard Model, the Cabibbo-Kobayashi-Maskawa (CKM) matrix is the only source of charge-paritiy violating interactions. Such are needed to explain the matter dominance of today's universe and are only possible if matter and antimatter exhibit different properties. Our group is world leading in the determination of the CKM matrix elements Vub and Vcb, whose size describe the coupling strength of the weak interaction between beauty and charm or beauty and up quarks. The ratio of |Vub|/|Vcb| directly constrains the allowed amount of of matter-antimatter asymmetry. Intriguingly different methods lead to different amounts! We are on the forefront to explore and substantiate these differences, to develop a better understanding of the matter-antimatter symmetry breaking meachnisms of the quark sector. 

© Florian Bernlochner


Besides the experimental study of beauty quarks, we are also involved in exploring the phenomenlogy of beauty hadron decays. This we do frequently in collaboration with other world leading scientist. We produced one of the most precise predictions on the ratios R(D/D*), and provided predictions on the dynamics of many semileptonic decay processes, also such that are studied at the LHC with LHCb. 

© SiLAB Bonn and PXD collaboration

Detector Development

Our group is also very involved in the development and depoloyment of modern pixel detector, in close collaboration with the group of Prof. Dr. Jochen Dingfelder. We are currently deploying the Belle II pixel detector, which is instrumental to achieve the physics goals of the experiment. We further are carrying out also research on next generation CMOS detectors and what role they can play in a future upgrade of the Belle II experiment.


© Colourbox

Dr. Felix Metzner

Dr. Felix Metzner is carrying out cutting edge research on the precision determination of semitauonic rates using the Belle and Belle II experiments.

© Colourbox

Dr. Markus Prim

Eine Wissenschaftlerin und ein Wissenschaftler arbeiten hinter einer Glasfassade und mischen Chemikalien mit Großgeräten.
© Colourbox

Dr. William Sutcliffe

Dr. William Sutcliffe is involved in the Belle II experiment and is interested in precision determinations of CKM matrix elements, machine learning, and until recently was the leader of the missing energy physics group.


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Florian Bernlochner


Nußallee 12

53115 Bonn

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Valja Gebhardt


Nußallee 12

53115 Bonn

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