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Dr Ulla Blumenschein

Ulla

Senior Lecturer in Particle Physics

Email: u.blumenschein@qmul.ac.uk
Telephone: 020 7882 6967
Room Number: G. O. Jones Building, Room 407
Office Hours: Tuesdays, 9-10 am, Mondays, 1-2pm

Profile

Qualifications:

  • Diploma in Biology (corresponds to an MSci), Mainz University
  • PhD in Physics, Freiburg University
  • Habilitation (higher education qualification), Goettingen University

Research Expertise:

  • Plant physiology (physiological indicators of forest damage)
  • Particle detectors, Calorimetry: Construction of a PbF2 calorimeter and commissioning and operation of a steel-scintillator sampling calorimeter, calibration and monitoring readout, DCS and monitoring software
  • Particle detectors, Trigger: Monitoring, simulation, electron/photon trigger development, operation
  • Particle physics data analysis: QCD and EWK physics: analysis management and review, associated Z/W+jets production; Higgs physics: Yukawa coupling to fermions; Beyond-Standard-Model physics: Search for Supersymmetry (gauginos, leptons), search for heavy charged and neutral Higgs bosons (2HDM and other models), search for heave gauge bosons (Z')
  • Big data, AI (NN and BDT), software: Fortran, C++, python, data skimming and slimming management, analysis software management 

Academic positions:

From 2017 to 2021, I have been PhD progression tutor of the Particle Physics department (PPRC) at the School of Physics and Astronomy. I manage the STFC   PhD Training Grant (PhD scholarships) at the School of Physics and Astronomy for matters.  I am the contact for the Graduate training network GRADnet of the South East Physics network SEPnet and for the NExT Institute.

From 2020-23 I have been deputy exam board chair and acting exam board chair of the School of Physics and Astronomy.  In this role, I have managed the exam paper review and the execution of the semester A and the semester B main exams and of the summer LSR exams, interacted with external examiners and chaired several UG SEB meetings.

I have also been a member of the task forces for the development and implementation of a blended teaching approach at the School of Physics and Astronomy in the academic years 2020/21 and 2021/22. In this functionality, I have worked on the implementation of new assessment strategies and a hybrid classroom approach.

I am external examiner at the University of Edinburgh since 2023

I am a member of the DiRAC Oversight Committee and of the IRIS Resource Scrutiny and Allocation Panel

I am deputy leader of the PPRC ATLAS Level-1 calorimeter trigger group.  

Brief research summary

I have dedicated my physics research to High-energy physics at particle colliders.

During my UG studies at Mainz university, I participated in the construction of the A4 calorimeter at the MAMI accelerator at Mainz University, and in the construction of the Compass experiment at the SPS at CERN in Switzerland.

During my MSc in Mainz, I developed and performed a search for supersymmetric particles, sleptons, indirect production and through gaugino cascades, at the electron-positron collider at LEP. I managed to derive the first lower limit on the selectron mass which was independent of the mass difference to the lightest supersymmetric particle.

For my PhD with Freiburg university, I continued searching for supersymmetry: I established the first search for associated chargino-neutralino production in tri-lepton final states at the D0 experiment at the proton-antiproton collider Tevatron in Illinois. I was also responsible for the calorimeter control system, developed new triggers for isolated electrons and photons and designed the electron/photon trigger suite.

After the PhD, I moved to the ATLAS experiment as a postdoc with  IFAE Barcelona, where I managed the online and offline commissioning and the first operation of the ATLAS Tile calorimeter. I was also responsible for the analogue calibration and monitoring readout system. I developed the first feasibility study for in-situ jet calibration.

As a research assistant with Goettingen University, during LHC Run1, I developed the first measurement of associated Z+jets production and later managed all measurements with W and Z bosons. I also searched for Higgs bosons in decays to 2 tau-leptons. I have developed trigger monitoring software and participated in the operation of the ATLAS detector, as a calorimeter, trigger and monitoring expert and as a shift leader. I was appointed ATLAS analysis software coordinator at the critical phase where we reorganized the software for Run-2.

In LHC Run2, from 2015-2017, I have managed all ATLAS measurements of QCD and electroweak processes, a position where I reported directly to the Physics Coordination. I also published the first Z+jets cross-section measurement at cms energies of 13TeV and established the Higgs-Yukawa coupling to fermions, using Higgs decays to two tau-leptons. I also worked on tau identification and the reconstruction of di-tau final states. I participated in the operation of the ATLAS detector as ARC shift leader. During LHC Run2, I  moved to PPRC at QMUL.

Using the full ATLAS Run-2 data, I have performed the first measurement of the production of Z bosons in association with high-energetic jets. I have published  the first ATLAS measurement of the production of a Z boson in association with charm quarks and a measurement of the production of a Z boson in association with bottom quarks, both key backgrounds to Higgs and BSM searches. I have published a search for  a neutral heavy Higgs boson arising from 2HDM models and for new heavy gauge bosons, in decays to Z or W boson and light Higgs boson. I am preparing a publication for a  heavy charged Higgs bosons in decays to a W boson and a Higgs boson. I have also co-editored a review of ATLAS SM measurements at LHC Run2. 

I have published the first cross-section measurements of W and Z bosons and their cross-section ratios to top-quark production in the new LHC Run-3 at a cms energy of 13.6 TeV and I am preparing for a measurement of  the Yukawa coupling  of the Higgs boson to second-generation fermions, in the  di-muon  decay mode. I am also working on a measurement of the associated production of Z and two charm quarks, the key background  for the measurement of Higgs decays to charm quarks, my next project.

Teaching

UG teaching:

2008-2016:

  • Nuclear and Particle Physics (BSc/MSc, module-assistant)
  • Physics of the Higgs boson (BSc/MSc, module organizer)
  • Statistical data analysis (BSc/MSc, module organizer)
  • Physics of the atom-shell (BSc, module-assistant)
  • Physics laboratory (BSc, module-assistant)
  • Electronics laboratory (BSc/MSc, module-assistant)
  • Physics for chemists and engineers (BSc, module organizer)

2017/18:

  • SPA4601 Professional Skills for Scientists (1st year, Semester A, modul co-organizer)
  • SPA4321 Introduction to C++ (1st year, Semester B, modul organizer)
  • SPA7029U/P Collider Physics (4th year, Semester B, deputy module organizer)

2018/19:

  • SPA4601 Professional Skills for Scientists (1st year, Semester A, module co-organizer)
  • SPA5201 Physics Laboratory (Semester B, module co-organizer)
  • SPA7029U/P Collider Physics (4th year, Semester B, deputy module organizer)

2019/20:

  • SPA4601 Professional Skills for Scientists (1st year, Semester A, module organizer)
  • SPA6306 Elementary Particle Physics  (3rd year, Semester A, module  organizer)
  • SPA7029U/P Collider Physics (4th year, Semester B, deputy module organizer)

2020/21:

  • SPA6306 Elementary Particle Physics (3rd year, Semester B, module organizer)
  • SPA4122 Mathematical techniques II (1st year, Semester B, module-assistant)

2021/22:

  • SPA6306 Elementary Particle Physics (3rd year, Semester B, module organizer)
  • SPA5201 Physics Laboratory (Semester B, module-assistant)
  • SPA6403 Statistical Physics (SemesterB, module-assistant)

2022/23

  • SPA6328 Statistical Data Analysis (3rd year, Semester A, module organizer)
  • SPA6306 Elementary Particle Physics (3rd year, Semester B, module organizer)

2023/24

  • SPA6328 Statistical Data Analysis (3rd year, Semester A, module organizer)
  • SPA6306 Elementary Particle Physics (3rd year, Semester B, module organizer)

2024/25

  • SPA6328 Statistical Data Analysis (3rd year, Semester A, module organizer)
  • SPA6307 Particle and Nuclear Physics (3rd year, Semester B, module organizer)

 

Teaching development:

From 2008-2016, I have developed the lecture Physics of the Higgs boson and introduced two new experiments in the advanced laboratory course. I have also developed the course work for the new course Nuclear and Particle Physics.

At  QMUL, I have co-developed the course SPA4601 Professional Skills for Scientists and significantly upgraded the course SPA6306 Elementary Particpe Physics. I have developed the new course SPA6307 Particle and Nuclear Physics.

PG teaching:

  • Statistics course at the German Helmholtz-Allianz workshop, 2010
  • Coordination of seminar presentations and Lecture LHC results at the German Autumn School of particle physics, 2011 and 2015
  • The organisation of  the NExT School 25-28 June 2018 at QMUL
  • Lecture Standard Model and Electroweak Physics at the Hadron Collider Summer School 2019 in Goettingen
  • Lecture series  Precision Tests of the Standard Model at the Departamento de Fisica de CIVESTAV, Mexico, 2019 in Mexico City
  • Lecture LHC SM, top and B physics, London Intercollegiate Particle Physics course, 2020, 2021 and 2022
  • Lecture Standard Model and electroweak Physics, at the Hadron Collider Summer School 2021 and 2022 in Goettingen.
  • Organisation of the XII NExT PhD workshop 2023 at QMUL
  • DPA Detector development Graduate Lecture Series: Lectures on Electronics and Particle Interaction with matter in 2021 and  2022 
  • Introduction into electronics and circuit analysis, UK instrumentalisation training, 2022 and 2023

PhD Students:

Current:

  • Jacob Oliver: Production of Z bosons in association with bottom and charm quarks at ATLAS
  • Sid Luke Baines: Search for a Charged Higgs Boson at ATLAS
  • Alex Gavin:  Production of Z bosons in association with  charm  quarks and search for Higgs bosons decaying to charm quarks

Graduated:

  • Tong Qiu: Search for a massive Higgs boson with the ATLAS detector at the LHC experiment
  • Arran Freegard: Higher-order QCD & EW corrections for high-energy V+jets production

PhD examination:

  • 5 PhD vivas as an internal examiner at QMUL
  • 3 PhD vivas at other UK universities
  • 5 PhD vivas  as external examiner overseas

PhD Projects:

Current BSC and MSc projects:

MEASUREMENT OF THE  HIGGS BOSON CROSS SECTION AT THE LHC

The Higgs boson decay into four muons is one of the cleanest Higgs decay channels. After the  discovery of the Higgs boson, it is important to measure the Higgs boson cross sections at high precision.

The student will  analize  real LHC data and simulations, optimising  a python-based framework to separate Higgs-boson candidates from the backgrounds and derive  cross section measurements in several  kinematic ranges.

MEASUREMENT OF THE HIGGS BOSON MASS AT THE LHC

The Higgs boson decay into four muons is one of the cleanest Higgs decay channels. After the  discovery of the Higgs boson, this channel can be used to measure the mass of the Higgs boson, one of the fundamental parameters of the Standard Model..

The student will  analize  real LHC data and simulations, optimizing  a python-based framework to separate Higgs-boson candidates  from the backgrounds and use them to measure the Higgs boson mass.

CROSS SECTION OF A Z BOSON IN ASSOCIATION WITH CHARM QUARKS  

Higgs boson decays into charm quarks will constitute one of the most important processes, expected to  be observed for the first time at the Large Hadron Collider (LHC) in the coming years. The most important background  for these searches is a Z boson produced in association with charm quarks.  Unfortunately, this background is insufficiently modelled in current LHC simulations.

The student will  optimise a python-based framework to separate  Z bosons decaying into two muons and produced in  association with charm quarks to measure their cross section in several kinematic regions. A critical issues if the selection of the two charm quarks via the characteristic decays of the charmed D-mesons.

NEURAL-NET BASED SEARCH FOR A  NEW HEAVY CHARGED HiGGS BOSON  

Several hypothetical extensions of the Standard model predict the existence of additional Higgs bosons, which are typically expected to be heavier than the Standard-Model Higgs boson and can even be electrically charged. A charged Higgs boson can potentially decay into a W boson and the Standard-model Higgs boson.
The student will develop a neural net to optimally seperate these hypothetical events from knowm Standard-Model backgrounds  and use it to perform a search for a charged Higgs boson.

 

Former BSc and MSc Projects:

  • Regularized unfolding in hadron collider measurements
  • Associated production of Z bosons with c or b quarks
  • Using Machine Learning  to improve the search for new heavy Higgs bosons
  • Review of 2-Higgs-Doublet models and experimental tests at colliders
  • ATLAS Level-1 calorimeter trigger upgrade: simulation and monitoring
  • Measurement of Z cross sections at the ATLAS experiment

 

Undergraduate Teaching

 

 

 

 

Research

Research Interests:

I am interested in the Fundamental forces in nature.  By recreating conditions of the early universe in powerful synchrotrons like the Large Hadron Collider (LHC), we aim to improve our understanding of the various forces with the hope to eventually be able to describe them in a unified theory.

The precision of the theoretical description of interactions in high-energy collisions has increased dramatically over the past years, prompting us to test them at a high precision level, with the option to find signs for new physics in deviations from the current models. In the ATLAS experiment, I have been investigating in particular the Strong Force by measuring processes where jets of hadrons are produced in association with the massive carriers of the weak force (JHEP 07 (2013) 032 Eur. Phys. J. C77 (2017) 361).  Recently, I have published measurements on two challenging classes of these interactions:  Processes with a Z boson and bottom or charm quarks in the final state (Eur. Phys. J. C 84 (2024) 984) and processes where a collinear Z boson is radiated by a high-energetic quark in the final state (JHEP 06 (2023) 080). Both processes can mimic important new physics interactions, and must hence be modelled with high precision.  Currently I am measuring the cross-section of the associated production of Z and two charm quarks, the main background for a measurement of Higgs decays to charm quarks.

In our Standard Model, the breaking of Electroweak symmetry by the Higgs field leads to massive force carriers and at least one Higgs boson, which was discovered at the LHC in 2012.  I have contributed heavily  to establish the Yukawa coupling of the Higgs to fermions, which is crucial to generate the fermion masses (JHEP 04 (2015) 117). So far, only Higgs couplings to 3-rd generation fermions have been  experimentally established. I am currently focussing on the new research frontier, the Higgs coupling to second-generation fermions, muons and charm quarks. 

Models which go beyond that and predict two Higgs doublets (2HDM)  with five massive Higgs bosons, could help understand why we have more matter than anti-matter in our universe. In such a model, a heavy new Higgs boson could be produced at the LHC and decay into the light Higgs and a Z boson. I have searched  for such processes in final states with leptons and b-quarks (JHEP 06 (2023) 016). I am currently working on a search for the production of a heavy charged Higgs boson decaying into a W boson and a light Higgs boson.

Publications

Selected publications:

ALEPH experiment:

  • A. Heister et al., [ALEPH Collaboration], Absolute Lower Limits on the Masses of Selectrons and Sneutrinos in the MSSM, Phys. Lett. B 544 (2002) 73-88

D0 experiment:

  • V. M. Abazov et al. [D0 Collaboration], Search for supersymmetry via associated production of charginos and neutralinos in final states with three leptons, Phys. Rev. Lett. 95 (2005) 151805.

ATLAS experiment, LHC Run1

  • K. J. Anderson et al., A Mobile Data Acquisition System, JINST 2, P07002 (2007).
  • G. Aad et al. [ATLAS Collaboration], Measurement of the Z to tau cross-section with the ATLAS detector, Phys. Rev. D 84, 112006 (2011).
  • G. Aad et al. [ATLAS Collaboration], Measurement of the production cross-section for Z/gamma* in association with jets in pp collisions at √s = 7 TeV with the ATLAS detector, Phys. Rev. D 85 (2012) 032009.
  • G. Aad et al. [ATLAS Collaboration], Search for the Standard Model Higgs boson in the H to tau+ tau- decay mode in √s = 7 TeV pp collisions with ATLAS , JHEP {09} (2012) 070.
  • G. Aad et al. [ATLAS Collaboration], Measurement of the production cross-section of jets in association with a Z boson in pp collisions at √s = 7 TeV with the ATLAS detector, JHEP 07(2013) 032.
  • G. Aad et al.[ATLAS Collaboration], Evidence for the Higgs-boson Yukawa coupling to tau leptons with the ATLAS detector, JHEP 04 (2015) 117.
  • G.Aad et al. [ATLAS Collaboration], Identification and energy calibration of hadronically decaying tau leptons with the ATLAS experiment in pp collisions at √s = 8 TeV, Eur. Phys. J. C (2015).

ATLAS experiment, LHC Run2

  • G. Aad et al. [ATLAS Collaboration], Measurement of W and Z-boson production cross-sections in pp collisions at √s = 13 TeV with the ATLAS detector, Phys. Lett. B 759 (2016) 601.
  • G. Aad et al. [ATLAS Collaboration], Measurements of the production cross-section of a Z boson in association with jets in pp collisions at √s =13 TeV with the ATLAS detector, Eur. Phys. J. C77 (2017) 361.
  • M. Aaboud et al. [ATLAS Collaboration], Cross-section measurements of the Higgs boson decaying into a pair of tau-leptons in proton-proton collisions at √s = 13 TeV with the ATLAS detector, Phys. Rev. D 99 (2019) 072001
  • M. Aaboud et al. [ATLAS Collaboration], Evidence for the production of three massive vector bosons with the ATLAS detector, Phys. Lett. B 798 (2019) 134913
  • M. Aaboud et al. [ATLAS Collaboration], Measurements of the production cross-section for a Z boson in association with b-jets in proton-proton collisions at √s = 13 TeV with the ATLAS detector, JHEP 07 (2020) 044
  • M. Aaboud et al. [ATLAS Collaboration], Cross-section measurements for the production of a Z boson in association with high transverse momentum jets in pp collisions at √s = 13 TeV with the ATLAS detector, accepted by JHEP, preprint
  • M. Aaboud et al. [ATLAS Collaboration],  Search for heavy resonances decaying into a Z or W boson and a Higgs boson in final states with leptons and b-jets in 139 fb−1 of pp collisions at √s = 13 TeV with the ATLAS detector, accepted by JHEP, preprint
  • M. Aaboud et al. [ATLAS Collaboration], Modelling and computational improvements to the simulation of single vector-boson plus jet processes for the ATLAS experiment, JHEP 08 (2022) 089
  • M. Aaboud et al. [ATLAS Collaboration], Measurement of the W-boson mass and width with the ATLAS detector using proton-proton collisions at s√ = 7 TeV, accepted by EPJC, preprint
  • M. Aaboud et al. [ATLAS Collaboration], Measurements of the production cross-section for a Z boson in association with b- or c-jets in proton-proton collisions at s√=13 TeV with the ATLAS detector, Eur. Phys. J. C 84 (2024) 984,  preprint

ATLAS experiment, LHC Run3

  • M. Aaboud et al. [ATLAS Collaboration], Measurement of vector boson production cross sections and their ratios using pp collisions at s√=13.6 TeV with the ATLAS detector, Phys. Lett. B 854 (2024) 138725   preprint

Other

  • A. Belyaev, U. Blumenschein et al., Multilepton signatures from dark matter at the LHC, JHEP 09 (2022) 173

Reviews:

  • U. Blumenschein et al., Pushing the precision frontier at the LHC with V+jets', hep-ex/1802.02100 .
  • U. Blumenschein, Jet production in association with vector bosons or top quarks ,Int. J. Mod. Phys. A, 30, 1546007 (2015).
  • ATLAS collaboration,  Electroweak, QCD and flavour physics studies with ATLAS data from Run 2 of the LHC, submitted to Physics Reports, preprint

All publications:

 

Supervision

This is not an exhaustive list and I would be happy to discuss other project possibilities.

 
                                             Project Title 

 

 

Search for a massive Higgs boson

Production of a Z boson in association with jets

 

Public Engagement

EPPOG master classes

In 2018, I have organised the EPPOG Master Classes in QMUL

St Pauls summer school

In 2019, 2022, 2023 and 2024 I have given lectures about particle accelerators at the St Pauls summer school 

Brampton Manor Academy Talks:

In Feb 2023, I have  given a lecture about particle accelerators at the  Brampton Manor Academy Talks

Offer Holder Days

I have given tester lectures at several Offer Holder Events

QMUL Festival of Communities

I have participated in the QMUL Festival of Communities 2023 with a new interactive experiment

 

 

 

 

 

Performance

  • Conference organisation:

    Talks at international conferences:

    • Sfermions at LEP2, Higgs and Supersymmetry Conference, 2001 in Orsay on behalf of the LEP experiments.
    • Limits on the mass of the lightest supersymmetric particle at LEP, 16th Int. Conf. on Particles and Nuclei (PANIC) 2002 in Osaka on behalf of the LEP experiments. 
    • Search for Associate Chargino Neutralino Production in the Trilepton Final States, Meeting of the Division of Particles and Fields of the American Physical Society, (PDF) 2004 in Riverside, on behalf of the D0 Collaboration
    • Jets and Jets+MET Studies at the LHC, Rencontres de Moriond, QCD and High Energy Interactions 2008, on behalf of the ATLAS Collaboration
    • ATLAS WZ Physics, LHC days 2010 in Split, Croatia, on behalf of the ATLAS Collaboration
    • ATLAS W/Z+jets, LHC EW WG meeting, Nov 2011 in Geneva, on behalf of the ATLAS Collaboration
    • ATLAS SM and top Physics, 13th Marcel Grossmann Meeting, 2012 in Stockholm, on behalf of the ATLAS Collaboration.
    • V+jets measurements at ATLAS, CERN LPCC seminar, 2013, Geneva, Switzerland
    • Measurements of the production of vector bosons in association with heavy flavour quarks at the LHC, LHCP in New York, 2014, on behalf of the ATLAS Collaboration.
    • Top and electroweak measurements, plenary presentation at the 38th International Conference on High Energy Physics (ICHEP 2016) in Chicago, 2016.
    • QCD measurements at the LHC, LFC17, Old and New Strong Interactions from LHC to Future Colliders, Villazzano, Trento, Italy, 2017
    • Standard-Model measurements at the LHC, Joint APP and HEPP Annual Conference, Bristol, 2018    
    • Differential measurements of the Drell-Yan cross-sections, presentation at the XXVI International Workshop on Deep-Inelastic Scattering and Related Subjects, DIS, in Kobe, Japan, 2018.
    • Precision measurements at ATLAS and CMS, international DESY Theory Workshop, Hamburg, Germany, 2018
    • Measurements of multi-boson production at ATLAS, International Conference on High Energy Physics (ICHEP 2022) in Bologna, 2022.
    • Recent V+heavy flavor measurements with 13 TeV data (ATLAS + CMS + LHCb), Standard Model at LHC in Rome (2024)
    • Experimental perspective of the future SM LHC program, General Meeting of the LHC Electroweak Working Group, Geneva (2024)

Grants

Oct 2017:  STFC grant to support  the 8th NExT workshop at QMUL

Jan 2018:  STFC Consolidated Grant for PPRC

Nov. 2020: RS travel exchange grant

Oct 2021: STFC Consolidated Grant for PPRC

Dec 2022:  STFC grant to support  the 13th NExT workshop at QMUL

2024: STFC Consolidated Grant for PPRC

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