Research Achievements

My primary research interest has been the discovery of the Higgs boson and to search for new physics processes that can probe potential differences in the interactions of the different fermion flavours. To this end, I have been using the tau lepton as my primary tool: I have developed standard and low-momentum tau reconstruction algorithms [1, 2, 3]. I have pioneered a method for measuring tau polarization at the CMS [4]. I have served as coordinator of the tau-lepton identification group. Armed with this, I have made key contributions to several physics analyses, spanning from low-q2 to high-q2, that can be illuminated using the tau lepton (below, in brackets where appropriate, I write the names of students whom I [co-]supervised, in order to achieve each research project; please see my CV for more details);

1. The first observation of top-quark pair production in a tau-lepton final state at the LHC [5];

2. The observation of the Higgs boson in its decay to tau leptons [6, 7], led to the first demonstration of the Yukawa-type fermion coupling of the Higgs boson [E. Nibigira, M. Štefko, S. Smith];

3. A search for low-mass [8] [I. Neutelings] and high-mass di-tau resonances [9] beyond the standard model. I also searched for single top-quark production in association with a Higgs boson decaying to a pair of leptons [10];

4. A new search for singly-produced on-shell leptoquark that decays into a tau lepton and a bottom quark, as compatible with the recent B-physics anomalies [11]. I also performed future projection studies [12, 13] and this has been one of the important inputs to the European Strategy Committee [P. Matorras].

5. Comprehensive searches for on- and off-shell leptoquark signals using full Run-2 data [14] [I. Neutelings]; We observed an excess of events with more than three standard deviations and I am playing a leading role in the task-force group that studies this excess more in-depth;

6. Indirect searches for new physics through the B-meson decay, Bc → J/ψτν, inspired by the reported anomalies in the b → cτν transition by the LHCb collaboration; it is now close to completion. To do this measurement, I have pioneered a low-momentum tau reconstruction algorithm [2] that can reconstruct tau leptons with momentum as low as a few GeV [V. Mikuni]. I’ve convened the “Violation of Fundamental Symmetry” group and led the wide range of efforts to measure the B-physics anomalies using more than 1010 B hadron events collected by CMS during 2018, called B-parked data [15];

7. Established special triggers to collect a hugely increased number of B-hadron events with ee final states for LHC Run 3 [M. Huwiler]. This trigger will dramatically improve our sensitivity for Lepton Flavour Universality tests using B-meson decays. I also convened this trigger development group.

8. The first measurement of the tau g-2 parameter at CMS using low-momentum hadronic taus in heavy ion collision data [16] [A. Jofrehei].

My unique developments have pushed forward the frontier of physics capabilities in CMS and I was awarded the CMS young researcher’s prize in 2022 [17]. I represented the CMS collaboration in a high-profile plenary and invited talks at prestigious international conferences; as of October 2022, I have given 17 presentations including Moriond, LHCP, SUSY, and EPS conferences — please see my list of publications.

Detector development is also a core part of my research activities. Currently, I am involved in the phase-2 High-Luminosity LHC upgrade of the endcap pixel detector, called TEPX. In particular, using prototype pixel detector modules with a complete set of components (pixel modules, electrical readout, mechanics), I am working to establish quality assurance and quality control procedures as well as automated tuning and testing procedures [18]. In the past, I contributed to the earlier upgrade of the CMS pixel detector [19, 20] (2016), the upgrade of the CMS hadron calorimeter (2013), and the commissioning of the ATLAS muon trigger detector [21] (2006–2013).

Finally, I have served on the CMS analysis review committees for five different analyses, as well as serving as a referee for five scientific journals (EPJC, JHEP x 2, PLB and SciPost). I also contributed to the review processes of many CMS scientific papers through institutional reviews and collaboration-wide reviews.