Dr Kristin Lohwasser

School of Mathematical and Physical Sciences

Senior Lecturer in Experimental Particle Physics

Kristin Lohwasser
Profile picture of Kristin Lohwasser
+44 114 222 4547

Full contact details

Dr Kristin Lohwasser
School of Mathematical and Physical Sciences
Hicks Building
Hounsfield Road
S3 7RH

As a researcher at the University of Sheffield I am investigating fundamental particles and their interactions as a member of the ATLAS collaboration. With an ERC starting grant, I am currently building up a small research group.

I completed my diploma studies successfully at the University of Dortmund with a thesis on the efficiency of a fast track trigger at the H1 experiment to select D-star bosons for the measurement of quark-gluon fusion, sensitive to the charm content of the proton.

During my studies, I spent half a year in Prague to study Astrophysics at the Charles University. In addititon to my diploma in physics, I completed a degree in journalism, including a one-year internship at a newspaper, with a thesis on a science popularisation in museum for mathematics.

After my undergraduate studies, I read Particle Physics in Oxford and completed a DPhil as a member of the ATLAS Collaboration. The topic of my thesis were studies on directly reconstructing the W asummetry at the LHC and using this measurement to constrain the parton distribution functions.

I further went to work as post-doctoral researcher at Freiburg University in Germany and at the DESY laboratory in Zeuthen, near Berlin.

Research interests

Particle physics attempts to describe the building blocks of matter and the fundamental forces between them. Our current understanding is encoded in the Standard Model (SM) theory of particle physics which combines our description of quantum chromodynamics (QCD) and electroweak (EWK) theory.

The SM allows us to make very precise predictions that have been confronted with experimental measurements at high-energy colliders over the past century – with incredible success.

The last missing piece of the SM was the experimental proof of the actual existence of the Higgs boson that had been hypothesised for more than 50 years.

Despite this obvious success of the SM, there are however flaws in the theory: There are observations in astrophysics and cosmology that the SM does not account for. Thus the pressing goal of particle physics today is to go beyond the SM so as to explain these contradictory observations.

In order to do so, particle physicists strive to discover new physics phenomena.

A technique exploited by a majority of physicists at the current LHC experiments to search for new physics phenomena are direct searches for new physics, testing very specific theories which only cover parts of possible new physics models.

An alternative powerful strategy to discover new physics is precision measurements of well-known processes.

This requires a profound knowledge of the underlying theory and also a very good understanding of the detector performance – which is both extremely challenging but at the same time extremely rewarding in terms of possible advancement of knowledge of particle physics.

Since so far no other new phenomena have been directly discovered at the LHC, it is paramount to pursue precision measurements with sensitivity to new phenomena.

One class of processes, suited to do so, is the production of pairs of bosons at the LHC, in particular of W and Z bosons. These fundamental particles are the “force carriers” of the SM, mediating how the other particles of the SM interact with one another.

The interactions between multiple W and Z bosons are particularly delicate towards the influences of new physics phenomena at higher scales.

These can be introduced based on effective field theory (EFT). New physics will manifest itself in these additional degrees of freedom, so called higher-dimensional operators which will modify how pairs of W and Z bosons are produced in high-energy collisions at the LHC.

Measuring the pair production of W bosons, also called diboson production processes, is therefore a window towards new phenomena at higher energy scales.

Research topics

Measurements of the production of pairs of W bosons and ATGC studies and extractions

Pairs of W bosons can be produced at the LHC either via proton-proton collisions or through the interaction of two photons or two W bosons that were emitted by protons. Measurements of these processes and a combined interpretation can achieve the best possible sensitivity to new physics models at the highest energy scales.

Improvements of Electron reconstruction and identification

A number of precision measurements and as well as searches for new physics rely crucially on the capability of the ATLAS detector to detect and accurately measure electrons. I have been involved in the efforts to develop reliable measurements of the electron selections efficiencies and to prepare the Run-2 data taking by optimizing the identification criteria for electrons.

Measurement of single boson production and Parton distribution functions (PDFs)

Reliable and accurate SM cross section predictions are needed to confront the data to extract hints for new physics scenarios at proton colliders. These are a convolution of the partonic cross sections and the PDFs. I have been worked on a number of precision measurements and used them to constrain the parton distributions from these measurements.

Upgrade of the ATLAS detector

The Upgrade of the ATLAS detector will allow to gather the data necessary to measure processes with a low cross-section. The ITk projects targets the upgrade of the current ATLAS inner tracking detector. My main focus was the testing of alternative sensor designs, which could also benefit further future experiments.


Show: Featured publications All publications

Journal articles

All publications

Journal articles