My talks

Title: McMule for MUonE
Date: 2025-11-07
Series: Liverpool MUonE Analysis Meeting
Location: Liverpool, England
Duration: 0h20

Title: RMCL2++: RadioMonteCarLow2++
Date: 2025-07-01
Series: Town Meeting, Hadron Physics in Horizon Europe
Location: Nantes, France
Duration: 0h10

Title: Cell resampling in McMule at NNLO
Date: 2025-05-06
Series: Negative-weights suppression in Monte Carlo samples
Location: CERN
Duration: 0h30

McMule, a Monte Carlo for MUons and other LEptons, implements many major QED processes at NNLO (eg. $ee\to ee$, $e\mu\to e\mu$, $ee\to\mu\mu$, $\ell p\to \ell p$, $\mu \to \nu\bar\nu e$) including effects from the lepton masses. This makes McMule suitable for predictions for low-energy experiments such as MUonE, CMD-III, ULQ2, or KLOE. In this talk I will discuss how we are implementing cellular resampling (2109.07851 & 2303.15246) directly as part of the generation step which further reduces the fraction of negative weights. I will show some preliminary results at NNLO for $ep\to ep$ for the ULQ2 experiment.

Title: Understanding the universe through precision measurements
Date: 2024-03-14
Series: Research Fellows Showcase 2025
Location: Liverpool, England
Duration: 0h15

What happened during the first second after the Universe began? What is Dark Matter? Particle physics aims to answer these and other questions by measuring the properties of the smallest constituents of matter in the large experiments across the world. After the discovery of the Higgs Boson in 2012, our best theory of nature at the smallest scale, the Standard Model, was completed. However, the Standard Model has many gaps: it does not provide a description of gravity or a candidate for Dark Matter, a form of matter we know must exist from astronomical observation but that we have never actually seen in the lab.

One of the ways to close this gap is to stress-test the Standard Model in precision measurements. The muon, a heavier cousin of the electron, is prime example of this. The muon's spin ever so slightly precesses in the presents of a magnetic field. By measuring this 'wobble' to 0.2 parts per million and comparing to the Standard Model, we hope to find lab-based evidence for New Physics (such as Dark Matter) or provide bounds on its absence.

As part of my research, I try to improve the Standard Model prediction for this and other precision measurements.

Title: Radiative corrections to lepton-nucleon scattering with McMule
Date: 2024-10-30
Series: Hadron Physics 2030
Location: Orsay, France
Duration: 0h30

Title: High-precision QED with McMule
Date: 2024-10-16
Series: Theoretical Physics Seminar
Location: Liverpool, England
Duration: 1h

In this talk I will introduce my research programme McMule, a Monte Carlo for MUons and other LEptons. McMule is designed as a framework for NNLO QED calculations and I will explain how these are performed. I will further discuss some future ideas for going beyond NNLO to N³LO and the inclusion of a YFS resummation. To highlight the need to go beyond NNLO I will discuss results for the MUonE experiment.

Title: McMule & RadioMonteCarLow 2
Date: 2024-10-07
Series: Muon Group Meeting
Location: Liverpool, England
Duration: 0h20

Title: The Radio MonteCarLow 2 activities
Date: 2024-09-10
Series: Seventh Plenary Workshop of the Muon g-2 Theory Initiative
Location: Tsukuba, Japan
Duration: 0h30

Title: Monte Carlo generators
Date: 2024-09-06
Series: Simon Eidelman School on Muon Dipole Moments and Hadronic Effects
Location: Nagoya, Japan
Duration: 1h30

Title: Towards QED at N³LO
Date: 2024-07-03
Series: TUM-MPP Collider Phenomenology Seminar Series
Location: Garching b. München, Germany
Duration: 1h

The hadronic contributions to the anomalous magnetic moment of the muon cannot be calculated perturbatively and is usually measured experimentally in $ee\to\text{hadrons}$. This measurement is often carried out using radiative return where an extra hard photon is detected and thereby reducing the invariant mass of the hadrons. However, this increases the theoretical complexity of the event generators required to accurately model the process. An alternative but equally challenging method is the extraction in $e\mu \to e\mu$ through the MUonE experiment. Here, the signal is loop induced necessitating an understanding of the process to 10^-5.

To reach the required precision we require NNLO and even N³LO predictions in QED. In this talk, I will discuss the methods required to reach this goal and include results for 2→2 processes at NNLO.

Title: Towards QED at N³LO
Date: 2024-06-25
Series: Tuesday Particle Physics Seminar
Location: Karlsruhe, Germany
Duration: 1h

Title: μ-e scattering at 10ppm
Date: 2024-05-27
Series: QCD Seminar
Location: CERN
Duration: 1h

The MUonE experiment aims to provide a new, independent measurement of the hadronic vacuum polarisation (HVP) contribution to the muon g-2. Considering the disagreement between some recent lattice calculations and dispersive determinations, a third and fully independent result is extremely important. However, MUonE will require an unprecedented precision of 10^-5 to solve this disagreement.

I will introduce the MUonE experiment and explain the theory behind the our recent NNLO calculation as well as some future developments towards N³LO.

Title: Monte Carlo generator comparison studies
Date: 2024-04-22
Series: Muon g-2 Theory Initiative Spring 2024 meeting
Location: Zoom
Duration: 0h15

Title: μ-e scattering at 10ppm
Date: 2024-04-04
Series: Fermilab Theory Seminars
Location: Batavia, IL, USA
Duration: 1h

I will introduce the MUonE experiment and explain the theory behind the our recent NNLO calculation as well as

Title: NNLO QED for e-p and e-e scattering with McMule for PRad
Date: 2024-03-20
Series: Argonne MEP Seminar
Location: Lemont, IL, USA
Duration: 1h

Precise lepton-proton scattering experiments need similarly precise theory predictions. It is now possible to model electron-proton and electron-electron scattering at next-to-next-to-leading order (NNLO) in QED. These corrections can be similar in size or even larger than the two-photon exchange contribution that is often a goal of the measurement and hence need to be brought under control.

In this talk I will introduce the McMule framework for NNLO QED calculations and explain the theory background that is required to use it. I will then present results for the PRad experiments.

Title: μ-e scattering at 10ppm
Date: 2024-04-01
Series: Theory Seminar
Location: Newport News, VA, USA
Duration: 1h

I will introduce the MUonE experiment and explain the theory behind the our recent NNLO calculation as well as some future developments towards N³LO.

Title: MUonE -- μ-e scattering at 10ppm
Date: 2024-03-26
Series: University of Florida High Energy Physics Seminar
Location: Gainesville, FL, USA
Duration: 1h

I will review how MUonE will carry out its measurement and what is required to reach this ambitious goal with a focus on the theory-side and our recent NNLO calculation.

Title: μ-e scattering at 10ppm
Date: 2024-03-22
Series: HET Lunch Seminar
Location: Brookhaven, NY, USA
Duration: 1h

I will introduce the MUonE experiment and explain the theory behind the our recent NNLO calculation as well as some future developments towards N³LO.

Title: NNLO QED for l-p scattering with McMule for MUSE
Date: 2024-03-20
Series: CFNS Seminar
Location: Stony Brook, NY, USA
Duration: 1h

Precise lepton-proton scattering experiments need similarly precise theory predictions. It is now possible to model electron-proton and muon-proton scattering at next-to-next-to-leading order (NNLO) in QED. These corrections can be similar in size or even larger than the two-photon exchange contribution that is often a goal of the measurement and hence need to be brought under control.

In this talk I will introduce the McMule framework for NNLO QED calculations and explain the theory background that is required to use it. I will then present results for the MUSE experiments.

Title: McMule -- a Monte Carlo generator for low energy processes
Date: 2024-03-14
Series: ACAT 2024
Location: Stony Brook, NY
Duration: 0h15

McMule, a Monte Carlo for MUons and other LEptons, implements many major QED processes at NNLO (eg. $ee\to ee$, $e\mu\to e\mu$, $ee\to\mu\mu$, $\ell p\to \ell p$, $\mu \to \nu\bar\nu e$) including effects from the lepton masses. This makes McMule suitable for predictions for low-energy experiments such as MUonE, CMD-III, PRad, or MUSE.

Recently, McMule gained the ability to generate events at NNLO directly rather than just differential distributions. To avoid negative event weights it employs cellular resampling (2109.07851 & 2303.15246) directly as part of the generation step which further reduces the fraction of negative weights.

Title: Status of McMule: event generation at NNLO and future
Date: 2024-02-27
Series: 5^th MUonE Collaboration Meeting
Location: CERN
Duration: 0h20

Title: McMule -- Monte Carlo for MUons and other LEptons
Date: 2023-11-08
Series: II Workshop on Muon Precision Physics
Location: Liverpool, England
Duration: 0h15

Title: Broadening access to EDI work at IPPP in Durham
Date: 2023-09-14
Series: Redefining the status quo in academia — a GW4 EDI STEMM Conference
Location: Cardiff, Wales
Duration: 0h10

Title: Predictions for low-energy particle physics experiments
Series: Physics Department Award for Excellence 2023

Title: MUonE -- μ-e scattering at 10ppm
Date: 2023-06-23
Series: Desy Theory Seminar
Location: Hamburg, Germany
Duration: 1h

Title: QED at NNLO and beyond for precision experiments
Date: 2023-06-01
Series: Radcor 2023
Location: Crieff, Scotland
Duration: 0h30

Low-energy experiments allow for some of the most precise measurements in particle physics, such as g-2. To make the most of these experiments, theory needs to match the experimental precision. Over the last decade, this meant that even in QED next-to-next-to-leading order calculations (or even more in some cases) became necessary. I will discuss some of the challenges faced when dealing with QED corrections and discuss some possible solutions that we have implemented in McMule (Monte Carlo for MUons and other LEptons). McMule is a framework that we have developed to obtain NNLO predictions for a number of processes, such as $e\mu\to e\mu$, $ee\to ee$, and $\mu\to e\nu\bar\nu$.

Title: MUonE -- μ-e scattering at 10ppm
Date: 2023-03-10
Series: IPPP Internal Seminar
Location: Durham, England
Duration: 1h

I will review how MUonE will carry out its measurement and what is required to reach this ambitious goal with a focus on the theory-side and our recent NNLO calculation.

Title: Summary of the N³LO workshop
Date: 2022-11-16
Series: MITP workshop: 'The Evaluation of the Leading Hadronic Contribution to the Muon g-2: Toward the MUonE Experiment'
Location: Mainz, Germany
Duration: 0h10

Title: Introduction to McMule
Date: 2022-11-16
Series: MITP workshop: 'The Evaluation of the Leading Hadronic Contribution to the Muon g-2: Toward the MUonE Experiment'
Location: Mainz, Germany
Duration: 0h10

Title: QED corrections for precision experiments
Date: 2022-10-18
Series: Particle Physics Seminars
Location: Vienna, Austria
Duration: 1h

I will discuss some of the challenges faced when dealing with QED corrections and discuss some possible solutions that we have implemented in McMule (Monte Carlo for MUons and other LEptons). McMule is a framework that we have developed to obtain NNLO predictions for a number of processes, such as $e\mu \to e\mu$, $ee \to ee$ and $\mu \to e\nu\bar\nu$.

Title: QED calculations at NNLO (and beyond)
Date: 2022-09-29
Series: MITP workshop 'Power Expansions on the Lightcone: From Theory to Phenomenology'
Location: Mainz, Germany
Duration: 1h

Title: QED calculations at NNLO (and beyond)
Date: 2022-09-27
Series: IPPP Steering Committee
Location: Durham, England (online)

Title: NNLO calculations for low-energy experiments
Date: 2022-09-22
Series: HP²
Location: Newcastle, England
Duration: 0h20

Title: NNLO results with McMule
Date: 2022-07-21
Series: ECT* workshop 'Radiative Corrections from medium to high energy experiments'
Location: Trento, Italy
Duration: 0h45

Title: QED corrections for precision experiments
Date: 2022-02-28
Series: Formal Seminar, University of Sussex
Location: Brighton, England
Duration: 1h

Low-energy experiments allow for some of the most precise measurements in particle physics, such as $g-2$. To make the most of these experiments, theory needs to match the experimental precision. Over the last decade, this meant that even in QED next-to-next-to-leading order calculations (or even more in some cases) became necessary.

Title: QED corrections for precision experiments
Date: 2021-12-02
Series: IKTP Seminar
Location: Dresden, Germany (online)
Duration: 1h

Title: McMule - QED Corrections for Low-Energy Experiments
Date: 2020-11-05
Series: Cavendish HEP Seminars
Location: Cambridge, England (online)
Duration: 1h

In the age of high-precision low-energy experiments such as MUonE or MEG, QED corrections start to become more and more important. To match the experimental error, we have developed McMule, an easily extendable framework for fully differential higher-order QED calculations of scattering and decay processes involving leptons.

I will discuss some of the theoretical underpinning for McMule, notably the FKS^l IR subtraction scheme and massification, as well as some recent phenomenological results we have obtained with McMule.

Title: Towards a NNLO Monte Carlo for MUonE
Date: 2020-02-12
Series: 2^nd MUonE Collaboration Meeting
Location: CERN, Switzerland
Duration: 0h30

Title: The FKS² subtraction scheme: status and future
Date: 2019-11-05
Series: PARTICLEFACE WG1 Meeting - WorkStop/ThinkStart 3.0: paving the way to alternative NNLO strategies
Location: Florence, Italy
Duration: 0h20

Title: High-precision QED prediction for low-energy lepton experiments
Date: 2019-10-23
Series: Physics of fundamental Symmetries and Interactions - PSI2019
Location: Villigen, Switzerland
Duration: 0h20

Past years have seen an impressive progress in perturbative calculations. We apply these techniques to compute high-precision QED contributions to low-energy processes involving muons and other leptons.

In this talk, I will review the current situation.

Title: Higher order corrections for muons
Date: 2019-05-20
Series: LTP Seminar
Location: Villigen, Switzerland
Duration: 0h20

Title: Masses in QED calculations: Massification and subtraction
Date: 2019-04-01
Series: Siegen Theory Seminar
Location: Siegen, Germany
Duration: 1h

Title: From matrix elements to a NNLO parton-level Monte Carlo for e-μ scattering
Date: 2019-02-05
Series: 2^nd workstop 'Theory for muon-electron scattering @ 10ppm'
Location: Zurich, Switzerland
Duration: 1h

Title: Fully differential predictions for lepton decays
Date: 2018-03-09
Series: Zurich PhD seminar
Location: Zurich, Switzerland
Duration: 0h20

Title: Muon decay at NNLO: Status Update
Date: 2018-02-21
Series: MITP topical workshop 'The Evaluation of the Leading Hadronic Contribution to the Muon Anomalous Magnetic Moment'
Location: Mainz, Germany
Duration: 0h45

Title: Fully differential NLO predictions for rare and radiative lepton decays
Date: 2017-09-29
Series: 19^th International Workshop on Neutrinos from Accelerators
Location: Uppsala, Sweden
Duration: 0h20

We present a general purpose Monte Carlo program for the calculation of the radiative ($\mu\to\nu\bar\nu e+\gamma$) and rare ($\mu\to\nu\bar\nu e+e^+e^-$) muon decays at NLO in the effective Fermi theory. These processes are irreducible Standard Model backgrounds to searches for lepton flavour violation at the PSI experiments MEG and Mu3e as they become indistinguishable from the corresponding signals when the neutrinos carry little energy.

Furthermore, we argue that fully differential NLO corrections are very important for the analysis of measurements aiming at the percent level or better. This is especally true of very stringent phase-space cuts are applied. To illustrate this, we use a recent tension between BaBar's recent measurement of the radiative tau decay and the Standard Model prediction as an example of such an analysis.

Title: Fully differential NLO predictions for rare and radiative lepton decays
Date: 2017-08-24
Series: Joint Annual Meeting of SPS and ÖPG
Location: Geneva, Switzerland
Duration: 0h15

We present a fully differential calculation at NLO of the radiative ($\mu\to\nu\bar\nu e+\gamma$) and rare ($\mu\to\nu\bar\nu e+e^+e^-$) muon decays in the effective Fermi theory keeping the full dependence on m_e. These processes are the irreducible background for the experimental searches for lepton flavour violation by MEG and Mu3e, as they become indistinguishable from the corresponding signals when the neutrinos carry little energy.

Aside from being a fundamental background, these processes are interesting in their own right. Using a tension between BaBar's recent measurement of $\mathcal{B}(\tau\to\nu\bar\nu{e+\gamma})$ and NLO predictions as an example, we show that fully differential NLO calculations are necessary for current and future measurements, especially when very stringent cuts are applied.

Title: Precise Standard Model predictions for the Mu3e and MEG experiment
Date: 2017-02-21
Series: 1^st PRISMA Interactive Research Symposium: A Matter of Flavor
Location: Mainz, Germany

The experiments MEG and Mu3e require a precise understanding of the Standard Model backgrounds for their searches for lepton flavour violating New Physics. These processes are the radiative ($\mu\to\nu\bar\nu e+\gamma$) and rare ($\mu\to\nu\bar\nu e+e^+e^-$) muon decays, respectively, as they become indistinguishable from the corresponding signals when the neutrinos carry little energy.

We present a fully differential calculation at NLO in the effective four fermion theory of these processes for muon and tau decays. Additionally, we augment the four fermion theory by higher dimensional operators to account for discrepancies between the NLO calculation and the experimental results of the radiative tau decay $\tau\to\nu\bar\nu e\gamma$.