### Conveners

#### Track 3: Computations in Theoretical Physics: Techniques and Methods

- Daniel Maitre
- Stefano Carrazza (CERN)

#### Track 3: Computations in Theoretical Physics: Techniques and Methods

- Stephen Philip Jones
- Maria Ubiali

#### Track 3: Computations in Theoretical Physics: Techniques and Methods

- Gudrun Heinrich (KIT)
- Andrey Pikelner (BLTP JINR)
- Myeonghun Park (University of Seoul, Department of Physics (KR))

#### Track 3: Computations in Theoretical Physics: Techniques and Methods

- latifa Elouadrhiri (Jefferson Lab)
- Myeonghun Park (University of Seoul, Department of Physics (KR))

### Description

This track focuses on computing techniques and algorithms used in the theoretical side of physics research.

More information of the scientific programme: https://indico.cern.ch/event/855454/program

Amplitude level evolution has become a new theoretical paradigm to analyze parton shower algorithms which are at the heart of multi-purpose event generator simulations used for particle collider experiments. It can also be implemented as a numerical algorithm in its own right to perform resummation of non-global observables beyond the leading colour approximation, leading to a new kind of...

In this talk we present a neural network based model to emulate matrix

elements. This model improves on existing methods by taking advantage of the known

factorisation properties of matrix elements to separate out the divergent regions.

In doing so the neural network learns about the factorisation property in singular limits, meaning we can control the behaviour of simulated matrix elements...

The demand for precision predictions in the field of high energy physics has increased tremendously over the recent years. Its importance is visible in the light of current experimental efforts to test the predictive power of the Standard Model of particle physics (SM) to a never before seen accuracy. Thus, advanced computer software is a key technology to enable phenomenological computations...

Scattering amplitudes in perturbative quantum field theory exhibit a rich structure of zeros, poles and branch cuts which are best understood in complexified momentum space. It has been recently shown that leveraging this information can significantly simplify both analytical reconstruction and final expressions for the rational coefficients of transcendental functions appearing in...

In this talk I will present REvolver, a c++ library for renormalization group evolution and automatic flavor matching of the QCD coupling and quark masses, as well as precise conversion between various quark mass renormalization schemes. The library systematically accounts for the renormalization group evolution of low-scale short-distance masses which depend linearly on the renormalization...

pySecDec is a tool for Monte Carlo integration of multiloop Feynman integrals (or parametric integrals in general), using the sector decomposition strategy. Its latest release contains two major features: the ability to expand integrals in kinematic limits using expansion by regions approach, and the ability to optimize the integration of weighted sums of integrals maximizing the obtained...

Non perturbative QED is used to predict beam backgrounds at the interaction point of colliders, in calculations of Schwinger pair creation and in precision QED tests with ultra-intense lasers.

In order to predict these phenomena, custom built monte carlo event generators based on a suitable non perturbative theory have to be developed. One such suitable theory uses the Furry Interaction...

We introduce the differentiable simulator MadJax, an implementation of the general purpose matrix element generator Madgraph integrated within the Jax differentiable programming framework in Python. Integration is performed during automated matrix element code generation and subsequently enables automatic differentiation through leading order matrix element calculations. Madjax thus...

We present the software framework underlying the NNPDF4.0 global determination of parton distribution functions (PDFs). The code is released under an open source licence and is accompanied by extensive documentation and examples. The code base is composed by a PDF fitting package, tools to handle experimental data and to efficiently compare it to theoretical predictions, and a versatile...

We present Qibo, a new open-source framework for fast evaluation of quantum circuits and adiabatic evolution which takes full advantage of hardware accelerators, quantum hardware calibration and control, and large codebase of algorithms for applications in HEP and beyond. The growing interest in quantum computing and the recent developments of quantum hardware devices motivates the development...

We compute the coefficients of the perturbative expansions of the plaquette,

and of the self-energy of static sources in the triplet and octet representation,

up to very high orders in perturbation theory. We use numerical sthocastic

perturbation theory and lattice regularization. We explore if the results

obtained comply with expectations from renormalon dominance, and what

they may say...

Modern machine learning methods offer great potential for increasing the efficiency of Monte Carlo event generators. We present the latest developments in the context of the event generation framework SHERPA. These include phase space sampling using normalizing flows and a new unweighting procedure based on neural network surrogates for the full matrix elements. We discuss corresponding...

Normalizing Flows (NFs) are emerging as a powerful brand of generative models, as they not only allow for efficient sampling, but also deliver density estimations by construction. They are of great potential usage in High Energy Physics (HEP), where we unavoidably deal with complex high dimensional data and probability distributions are everyday’s meal. However, in order to fully leverage the...

Phenomenological studies of high-multiplicity scattering processes at collider experiments present a substantial theoretical challenge and are increasingly important ingredients in experimental measurements. We investigate the use of neural networks to approximate matrix elements for these processes, studying the case of loop-induced diphoton production through gluon fusion. We train neural...

In this talk, I present the computation of the two-loop helicity amplitudes for Higgs boson production in association with a bottom quark pair. I give an overview of the method and describe how computational bottlenecks can be overcome by using finite field reconstruction to obtain analytic expressions from numerical evaluations. I also show how the method of differential equations allows us...

We propose a novel method for the elimination of negative Monte Carlo event

weights. The method is process-agnostic, independent of any analysis, and preserves all physical observables. We demonstrate the overall performance and systematic improvement with increasing event sample size, based on predictions for the production of a W boson with two jets calculated at next-to-leading order...

We present results for Higgs boson pair production in gluon fusion including both, NLO (2-loop) QCD corrections with full top quark mass dependence as well as anomalous couplings related to operators describing effects of physics beyond the Standard Model.

The latter can be realized in non-linear (HEFT) or linear (SMEFT) Effective Field Theory frameworks.

We show results for both and discuss...

In view of the null results (so far) in the numerous channel-by-channel searches for new particles at the LHC, it becomes increasingly relevant to change perspective and attempt a more global approach to finding out where BSM physics may hide. To this end, we developed a novel statistical learning algorithm that is capable of identifying potential dispersed signals in the slew of published LHC...

FeynCalc is esteemed by many particle theorists as a very

useful tool for tackling symbolic Feynman diagram calculations

with a great amount of transparency and flexibility.

While the program enjoys an excellent reputation

when it comes to tree level and 1-loop calculations,

the usefulness of FeynCalc in multi-loop projects is

often doubted by the practitioners.

In this talk I will...

We present the mixed QCD-EW two-loop virtual amplitudes for the neutral current Drell-Yan production. The evaluation of the two-loop amplitudes is one of the bottlenecks for the complete calculation of the NNLO mixed QCD-EW corrections. We present the computational details, especially the evaluation of all the relevant two-loop Feynman integrals using analytical and semi-analytical methods. We...

We present an application of major new features of the program pySecDec, which is a program to calculate parametric integrals, in particular multi-loop integrals, numerically.

One important new feature is the ability to integrate weighted sums of integrals in a way which is optimised to reach a given accuracy goal on the sums rather than on the individual integrals, another one is the option...

A high-precision calculation of lepton magnetic moments requires an evaluation of QED Feynman diagrams up to five independent loops.

These calculations are still important:

1) the 5-loop contributions with lepton loops to the electron g-2 are still not double-checked (and can potentially be sensitive in experiments);

2) there is a discrepancy in different calculations of the 5-loop...

An algorithm for the spinor amplitudes with massive particles is implemented in the SANC computer system framework.

Procedure for simplification of the expressions with spinor products is based on little group technique in six-dimensional space-time.

Amplitudes for bremsstrahlung processes e+e+\to (e+e+/mu+mu-/HZ/Zgamma/gamma gamma) + gamma are obtained in gauge-covariant form...

In recent work we computed 4-loop integrals for self-energy diagrams with 11 massive internal lines. Presently we perform numerical integration and regularization for diagrams with 8 to 11 lines, while considering massive and massless cases. For dimensional regularization, a sequence of integrals is computed depending on a parameter ($\varepsilon$) that is incorporated via the space-time...