Gerhard Buchalla
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Research Subjects
Gerhard Buchalla has a total of 23 co-authors. Here are the top co-authors by number of shared publications:
- Alejandro Celis
Ludwig-Maximilians-Universität München
8 shared publications - Claudius Krause
Austrian Academy of Sciences
6 shared publications - Gudrun Heinrich
Karlsruhe Institute of Technology
6 shared publications - Oscar Catà
Center for Particle Physics Siegen (CPPS), Theoretische Physik 1, Universität Siegen, Walter-Flex-Straße 3, D-57068 Siegen, Germany
5 shared publications - Ludovic Michel Scyboz
Monash University
4 shared publications - Matteo Capozi
Max Planck Institute for Physics
4 shared publications
Latest Publications
- Open Access
- 12 July 2026
- Published by Springer Nature in The European Physical Journal C
- Vol. 86 (7) , 794
Comment on “Primary Dimensions”
We show that the concept of primary dimensions , first introduced in [1] as an organizing principle for chiral Lagrangians, is inconsistent. Although this had been pointed out already in [2], the notion of primary dimensions has re-appeared in recent literature. We briefly comment on the proper power counting for such effective field theories, including the electroweak chiral Lagrangian with a light Higgs, which is based on chiral dimensions, equivalent to the counting of loop orders.
- 12 July 2026
- Published by Springer Nature in The European Physical Journal C
- Vol. 86 (7) , 794
Open AccessComment on “Primary Dimensions”
We show that the concept of primary dimensions , first introduced in [1] as an organizing principle for chiral Lagrangians, is inconsistent. Although this had been pointed out already in [2], the notion of primary dimensions has re-appeared in recent literature. We briefly comment on the proper power counting for such effective field theories, including the electroweak chiral Lagrangian with a light Higgs, which is based on chiral dimensions, equivalent to the counting of loop orders.
- Open Access
- 11 June 2025
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2025 (6) , 1-4
Erratum: Higgs boson pair production in non-linear Effective Field Theory with full mt-dependence at NLO QCD
- 11 June 2025
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2025 (6) , 1-4
Open AccessErratum: Higgs boson pair production in non-linear Effective Field Theory with full mt-dependence at NLO QCD
- Open Access
- 19 November 2024
- Published by Stichting SciPost in SciPost Physics
Correction: Loop counting matters in SMEFT
- 19 November 2024
- Published by Stichting SciPost in SciPost Physics
Open AccessCorrection: Loop counting matters in SMEFT
- Open Access
- 17 July 2024
- Published by American Physical Society (APS) in Physical Review D
- Vol. 110 (1) , 016015
Two-Higgs-doublet model matched to nonlinear effective theory
We use functional methods to match the two-Higgs-doublet model with heavy scalars in the nondecoupling regime to the appropriate nonlinear effective field theory, which takes the form of an electroweak chiral Lagrangian (HEFT). The effective Lagrangian is derived to leading order in the chiral counting. This includes the loop induced and local terms, which enter at the same chiral order as their counterparts in the Standard Model. An algorithm is presented that allows us to compute the coefficient functions to all orders in . Some of the all-orders results are given in closed form. The parameter regimes for decoupling, nondecoupling, and alignment scenarios in the effective field theory context and some phenomenological implications are briefly discussed.- 17 July 2024
- Published by American Physical Society (APS) in Physical Review D
- Vol. 110 (1) , 016015
Open AccessTwo-Higgs-doublet model matched to nonlinear effective theory
We use functional methods to match the two-Higgs-doublet model with heavy scalars in the nondecoupling regime to the appropriate nonlinear effective field theory, which takes the form of an electroweak chiral Lagrangian (HEFT). The effective Lagrangian is derived to leading order in the chiral counting. This includes the loop induced and local terms, which enter at the same chiral order as their counterparts in the Standard Model. An algorithm is presented that allows us to compute the coefficient functions to all orders in . Some of the all-orders results are given in closed form. The parameter regimes for decoupling, nondecoupling, and alignment scenarios in the effective field theory context and some phenomenological implications are briefly discussed. - Open Access
- 11 September 2023
- Published by Stichting SciPost in SciPost Physics
- Vol. 15 (3) , 088
Loop counting matters in SMEFT
We show that, in addition to the counting of canonical dimensions, a counting of loop orders is necessary to fully specify the power counting of Standard Model Effective Field Theory (SMEFT). Using concrete examples, we demonstrate that considering the canonical dimensions of operators alone may lead to inconsistent results. The counting of both, canonical dimensions and loop orders, establishes a clear hierarchy of the terms in SMEFT. In practice, this serves to identify, and focus on, the potentially dominating effects in any given high-energy process in a meaningful way. Additionally, this will lead to a consistent limitation of free parameters in SMEFT applications.
- 11 September 2023
- Published by Stichting SciPost in SciPost Physics
- Vol. 15 (3) , 088
Open AccessLoop counting matters in SMEFT
We show that, in addition to the counting of canonical dimensions, a counting of loop orders is necessary to fully specify the power counting of Standard Model Effective Field Theory (SMEFT). Using concrete examples, we demonstrate that considering the canonical dimensions of operators alone may lead to inconsistent results. The counting of both, canonical dimensions and loop orders, establishes a clear hierarchy of the terms in SMEFT. In practice, this serves to identify, and focus on, the potentially dominating effects in any given high-energy process in a meaningful way. Additionally, this will lead to a consistent limitation of free parameters in SMEFT applications.
- Open Access
- 24 April 2023
- Published by American Physical Society (APS) in Physical Review D
- Vol. 107 (7) , 076021
and with anomalous couplings at next-to-leading order in QCDWe generalize the next-to-leading order (NLO) QCD calculations for the decay rates of and to the case of anomalous couplings of the Higgs boson. We demonstrate how this computation can be done in a consistent way within the framework of an electroweak chiral Lagrangian, based on a systematic power counting. It turns out that no additional coupling parameters arise at NLO in QCD beyond those already present at leading order. The impact of QCD is large for and the uncertainties from QCD are significantly reduced at NLO. is only mildly affected by QCD; here the NLO treatment practically eliminates the uncertainties. Consequently, our results will allow for an improved determination of anomalous Higgs couplings from these processes. The relation of our framework to a treatment in Standard Model effective field theory is also discussed.- 24 April 2023
- Published by American Physical Society (APS) in Physical Review D
- Vol. 107 (7) , 076021
Open Accessand with anomalous couplings at next-to-leading order in QCDWe generalize the next-to-leading order (NLO) QCD calculations for the decay rates of and to the case of anomalous couplings of the Higgs boson. We demonstrate how this computation can be done in a consistent way within the framework of an electroweak chiral Lagrangian, based on a systematic power counting. It turns out that no additional coupling parameters arise at NLO in QCD beyond those already present at leading order. The impact of QCD is large for and the uncertainties from QCD are significantly reduced at NLO. is only mildly affected by QCD; here the NLO treatment practically eliminates the uncertainties. Consequently, our results will allow for an improved determination of anomalous Higgs couplings from these processes. The relation of our framework to a treatment in Standard Model effective field theory is also discussed. - Open Access$h\to gg$ and $h\toγγ$ with Anomalous Couplings at Next-to-Leading Order in QCDWe generalize the next-to-leading order QCD calculations for the decay rates of $h\to gg$ and $h\to\gamma\gamma$ to the case of anomalous couplings of the Higgs boson. We demonstrate how this computation can be done in a consistent way within the framework of an electroweak chiral Lagrangian, based on a systematic power counting. It turns out that no additional coupling parameters arise at NLO in QCD beyond those already present at leading order. The impact of QCD is large for $h\to gg$ and the uncertainties from QCD are significantly reduced at NLO. $h\to\gamma\gamma$ is only mildly affected by QCD; here the NLO treatment practically eliminates the uncertainties. Consequently, our results will allow for an improved determination of anomalous Higgs couplings from these processes. The relation of our framework to a treatment in Standard Model effective field theory is also discussed.Open Access$h\to gg$ and $h\toγγ$ with Anomalous Couplings at Next-to-Leading Order in QCDWe generalize the next-to-leading order QCD calculations for the decay rates of $h\to gg$ and $h\to\gamma\gamma$ to the case of anomalous couplings of the Higgs boson. We demonstrate how this computation can be done in a consistent way within the framework of an electroweak chiral Lagrangian, based on a systematic power counting. It turns out that no additional coupling parameters arise at NLO in QCD beyond those already present at leading order. The impact of QCD is large for $h\to gg$ and the uncertainties from QCD are significantly reduced at NLO. $h\to\gamma\gamma$ is only mildly affected by QCD; here the NLO treatment practically eliminates the uncertainties. Consequently, our results will allow for an improved determination of anomalous Higgs couplings from these processes. The relation of our framework to a treatment in Standard Model effective field theory is also discussed.
- Open Access
- 6 October 2021
- Published by American Physical Society (APS) in Physical Review D
- Vol. 104 (7) , 076005
Higgs-electroweak chiral Lagrangian: One-loop renormalization group equations
Starting from the one-loop divergences we obtained previously, we work out the renormalization of the Higgs-electroweak chiral Lagrangian explicitly and in detail. This includes the renormalization of the lowest-order Lagrangian, as well as the decomposition of the remaining divergences into a complete basis of next-to-leading-order counterterms. We provide the list of the corresponding beta functions. We show how our results match the one-loop renormalization of some of the dimension-6 operators in SMEFT. We further point out differences with related work in the literature and discuss them. As an application of the obtained results, we evaluate the divergences of the vacuum expectation value of the Higgs field at one loop and show that they can be appropriately removed by the corresponding renormalization. We also work out the finite renormalization required to keep the no-tadpole condition on the Higgs field at one loop.
- 6 October 2021
- Published by American Physical Society (APS) in Physical Review D
- Vol. 104 (7) , 076005
Open AccessHiggs-electroweak chiral Lagrangian: One-loop renormalization group equations
Starting from the one-loop divergences we obtained previously, we work out the renormalization of the Higgs-electroweak chiral Lagrangian explicitly and in detail. This includes the renormalization of the lowest-order Lagrangian, as well as the decomposition of the remaining divergences into a complete basis of next-to-leading-order counterterms. We provide the list of the corresponding beta functions. We show how our results match the one-loop renormalization of some of the dimension-6 operators in SMEFT. We further point out differences with related work in the literature and discuss them. As an application of the obtained results, we evaluate the divergences of the vacuum expectation value of the Higgs field at one loop and show that they can be appropriately removed by the corresponding renormalization. We also work out the finite renormalization required to keep the no-tadpole condition on the Higgs field at one loop.
- Open Access
- 28 February 2020
- Published by Sissa Medialab Srl
- Vol. 317, 072
Complete One-Loop Renormalization of the Higgs-Electroweak Chiral Lagrangian
The electroweak sector of the Standard Model can be formulated in a way similar to Chiral Perturbation Theory (ChPT), but extended by a singlet scalar. The resulting effective field theory (EFT) is called Higgs-Electroweak Chiral Lagrangian (EWCh$\mathcal{L}$) and is the most general approach to new physics in the Higgs sector. It solely assumes the pattern of symmetry breaking leading to the three electroweak Goldstone bosons (i.e. massive $W$ and $Z$) and the existence of a Higgs-like scalar particle. The power counting of the EWCh$\mathcal{L}$ is given by a generalization of the momentum expansion of ChPT. It is connected to a loop expansion, making the theory renormalizable order by order in the EFT. I will briefly review the construction of the EWCh$\mathcal{L}$ and its power counting. Then, I will discuss the complete one-loop renormalization of the EWCh$\mathcal{L}$ employing the background-field method and the super-heat-kernel expansion. This computation confirms the power counting assumptions, is consistent with the completeness of the operator basis, and reproduces known results of subsectors in the appropriate limits. Preprint numbers: FERMILAB-CONF-19-066-T- 28 February 2020
- Published by Sissa Medialab Srl
- Vol. 317, 072
Open AccessComplete One-Loop Renormalization of the Higgs-Electroweak Chiral Lagrangian
The electroweak sector of the Standard Model can be formulated in a way similar to Chiral Perturbation Theory (ChPT), but extended by a singlet scalar. The resulting effective field theory (EFT) is called Higgs-Electroweak Chiral Lagrangian (EWCh$\mathcal{L}$) and is the most general approach to new physics in the Higgs sector. It solely assumes the pattern of symmetry breaking leading to the three electroweak Goldstone bosons (i.e. massive $W$ and $Z$) and the existence of a Higgs-like scalar particle. The power counting of the EWCh$\mathcal{L}$ is given by a generalization of the momentum expansion of ChPT. It is connected to a loop expansion, making the theory renormalizable order by order in the EFT. I will briefly review the construction of the EWCh$\mathcal{L}$ and its power counting. Then, I will discuss the complete one-loop renormalization of the EWCh$\mathcal{L}$ employing the background-field method and the super-heat-kernel expansion. This computation confirms the power counting assumptions, is consistent with the completeness of the operator basis, and reproduces known results of subsectors in the appropriate limits. Preprint numbers: FERMILAB-CONF-19-066-T - Open Access
Complete One-Loop Renormalization of the Higgs-Electroweak Chiral Lagrangian
The electroweak sector of the Standard Model can be formulated in a way similar to Chiral Perturbation Theory (ChPT), but extended by a singlet scalar. The resulting effective field theory (EFT) is called Higgs-Electroweak Chiral Lagrangian (EWCh$\mathcal{L}$) and is the most general approach to new physics in the Higgs sector. It solely assumes the pattern of symmetry breaking leading to the three electroweak Goldstone bosons (i.e. massive $W$ and $Z$) and the existence of a Higgs-like scalar particle. The power counting of the EWCh$\mathcal{L}$ is given by a generalization of the momentum expansion of ChPT. It is connected to a loop expansion, making the theory renormalizable order by order in the EFT. I will briefly review the construction of the EWCh$\mathcal{L}$ and its power counting. Then, I will discuss the complete one-loop renormalization of the EWCh$\mathcal{L}$ employing the background-field method and the super-heat-kernel expansion. This computation confirms the power counting assumptions, is consistent with the completeness of the operator basis, and reproduces known results of subsectors in the appropriate limits.Open AccessComplete One-Loop Renormalization of the Higgs-Electroweak Chiral Lagrangian
The electroweak sector of the Standard Model can be formulated in a way similar to Chiral Perturbation Theory (ChPT), but extended by a singlet scalar. The resulting effective field theory (EFT) is called Higgs-Electroweak Chiral Lagrangian (EWCh$\mathcal{L}$) and is the most general approach to new physics in the Higgs sector. It solely assumes the pattern of symmetry breaking leading to the three electroweak Goldstone bosons (i.e. massive $W$ and $Z$) and the existence of a Higgs-like scalar particle. The power counting of the EWCh$\mathcal{L}$ is given by a generalization of the momentum expansion of ChPT. It is connected to a loop expansion, making the theory renormalizable order by order in the EFT. I will briefly review the construction of the EWCh$\mathcal{L}$ and its power counting. Then, I will discuss the complete one-loop renormalization of the EWCh$\mathcal{L}$ employing the background-field method and the super-heat-kernel expansion. This computation confirms the power counting assumptions, is consistent with the completeness of the operator basis, and reproduces known results of subsectors in the appropriate limits.