Publications

Order by: publication date number of citations

• Group invariants for Feynman diagrams

  Idrish Huet, Michel Rausch de Traubenberg, Christian Schubert

  SciPost Phys. Proc. 14, 031 (2023) · published 24 November 2023 | Toggle abstract · pdf

  It is well-known that the symmetry group of a Feynman diagram can give important information on possible strategies for its evaluation, and the mathematical objects that will be involved. Motivated by ongoing work on multi-loop multi-photon amplitudes in quantum electrodynamics, here I will discuss the usefulness of introducing a polynomial basis of invariants of the symmetry group of a diagram in Feynman-Schwinger parameter space.

• $\mathcal{O}(α_s^3)$ corrections to semileptonic $b \to c$ decays in the heavy daughter approximation

  Kay Schoenwald

  SciPost Phys. Proc. 7, 027 (2022) · published 21 June 2022 | Toggle abstract · pdf

  We present our recent calculation of the third order corrections to the semileptonic $b \to c$ and the muon decays. The calculation has been performed in an expansion around the limit $m_c \sim m_b$, but shows decent convergence even for $m_c=0$ from which the contribution to the muon decay can be extracted. For the semileptonic $b \to c$ decay we find large perturbative corrections in the on-shell scheme which can be significantly reduced by changing to the kinetic scheme for the bottom quark mass. These results are important input for the inclusive determination of $|V_{cb}|$ and the Fermi coupling constant $G_F$.

• On old relations of Lie theory, classical geometry and gauge theory

  Rolf Dahm

  SciPost Phys. Proc. 14, 025 (2023) · published 24 November 2023 | Toggle abstract · pdf

  Having been led by hadron interactions and low-energy photoproduction to SU(4) and non-compact SU*(4) symmetry, the general background turned out to be projective geometry (PG) of $P^3$, or when considering line and Complex geometry to include gauge theory, aspects of $P^5$. Point calculus and its dual completion by planes introduced quaternary (quadratic) "invariants" $x_{\mu}x^{\mu}=0$ and $p_{\mu}p^{\mu}=0$, and put focus on the intermediary form $(xu)$ and its treatment. Here, the major result is the identification of the symmetric 20 of SU(4) comprising nucleon and Delta states as related to the quaternary cubic forms discussed by Hilbert in his work on full invariant systems. So PG determines geometrically the scene by representations (reps) and invariant theory without having to force affine restrictions and additional (spinorial or gauge) rep theory.

• Lattice phase shifts and mixing angles for an arbitrary number of coupled channels

  Lukas Bovermann, Evgeny Epelbaum, Hermann Krebs, Dean Lee

  SciPost Phys. Proc. 3, 052 (2020) · published 27 February 2020 | Toggle abstract · pdf

  We present a lattice method for determining scattering phase shifts and mixing angles for the case of an arbitrary number of coupled channels. The proposed method combines a spherical wall boundary condition and a channel-mixing auxiliary potential to extract the full-rank S-matrix from the radial wave functions. We consider the scattering problem of two spin-1 bosons interacting with a test potential involving up to four coupled channels. For this benchmark system, the phase shifts and mixing angles are shown to agree on the lattice and in the continuum. Our method should allow to extend previous two-channel nuclear lattice EFT simulations to mixing of more than two partial waves.

• Central exclusive diffractive production of axial-vector $f_{1}$ mesons in proton-proton collisions

  Piotr Lebiedowicz, Josef Leutgeb, Otto Nachtmann, Anton Rebhan, Antoni Szczurek

  SciPost Phys. Proc. 8, 121 (2022) · published 13 July 2022 | Toggle abstract · pdf

  Exclusive production of axial-vector $f_{1}(1285)$ meson in proton-proton collisions via pomeron-pomeron fusion within the tensor-pomeron approach is discussed. Two ways to construct the pomeron-pomeron-$f_{1}$ coupling are presented. We adjust the parameters of our model to the WA102 experimental data and compare with predictions of the Sakai-Sugimoto model. Predictions for LHC experiments are given.

• Irreducible representations of $\mathbb{Z}_2^2$-graded supersymmetry algebra and their applications

  Naruhiko Aizawa

  SciPost Phys. Proc. 14, 016 (2023) · published 23 November 2023 | Toggle abstract · pdf

  We give a brief review on recent developments of $\mathbb{Z}_2^n$-graded symmetry in physics in which hidden $\mathbb{Z}_2^n$-graded symmetries and $\mathbb{Z}_2^n$-graded extensions of known systems are discussed. This elucidates physical relevance of the $\mathbb{Z}_2^n$-graded algebras. As an example of physically interesting algebra, we take $\mathbb{Z}_2^2$-graded supersymmetry (SUSY) algebras and consider their irreducible representations (irreps). A list of irreps for ${\cal N} = 1, 2$ algebras is presented and as an application of the irreps, $\mathbb{Z}_2^2$-graded SUSY classical actions are constructed.

• The 34th International Colloquium on Group Theoretical Methods in Physics

  Rutwig Campoamor-Stursberg, Marc de Montigny, Michel Rausch de Traubenberg, Mauricio Valenzuela

  SciPost Phys. Proc. 14, 001 (2023) · published 23 November 2023 | Toggle abstract · pdf

  Introduction to the proceedings of the 34th International Colloquium on Group Theoretical Methods in Physics.

• Prospects for Higgs and di-Higgs measurements at the ATLAS experiment

  Alessandra Betti

  SciPost Phys. Proc. 8, 117 (2022) · published 13 July 2022 | Toggle abstract · pdf

  The large dataset of about 3000 $\rm{fb}^{-1}$ that will be collected at the High Luminosity LHC (HL-LHC) will be used to measure Higgs boson processes in detail. This large dataset will also provide sensitivity to di-Higgs processes and will allow for the improvement of the constraints on the Higgs boson self coupling. Studies based on current ATLAS analyses using LHC Run 2 data have been carried out to understand the expected precision and limitations of the Higgs and di-Higgs measurements at the HL-LHC. This paper presents the ATLAS prospects for Higgs and di-Higgs results at the HL-LHC.

• Towards two- and three-loop QCD corrections to the width difference in $B_s-\bar{B}_s$ mixing

  Vladyslav Shtabovenko

  SciPost Phys. Proc. 7, 025 (2022) · published 21 June 2022 | Toggle abstract · pdf

  In this work we address the issue of large perturbative uncertainties in the theory prediction for $\Delta \Gamma_s$, the width difference in the $B^0_s - \bar{B}^0_s$ mixing process. To this aim we complete important steps towards the full analytic result for the previously unknown Wilson coefficients from the matching between $|\Delta B|=1$ and $|\Delta B|=2$ effective Hamiltonians at next-to-next-leading order (NNLO) in the strong coupling constant. We provide a thorough discussion of technical and conceptual difficulties behind this computation and give an outlook regarding the availability of the new NNLO theory prediction for $\Delta \Gamma_s$.

• Leading fermionic three-loop corrections to W-boson mass and Z-pole observables

  Lisong Chen, Ayres Freitas

  SciPost Phys. Proc. 7, 019 (2022) · published 21 June 2022 | Toggle abstract · pdf

  In this proceeding, we highlight the computation of leading fermionic three-loop corrections to electroweak precision observables (EWPOs) accomplished recently. We summarize the numerical analysis and provide an outlook.