SciPost Submission Page
LHC EFT WG Note: Basis for Anomalous Quartic Gauge Couplings
by Gauthier Durieux, Grant N. Remmen, Nicholas L. Rodd, Oscar J. P. Éboli, Maria C. Gonzalez-Garcia, Dan Kondo, Hitoshi Murayama, Risshin Okabe
Submission summary
| Authors (as registered SciPost users): | Nicholas Rodd |
| Submission information | |
|---|---|
| Preprint Link: | https://arxiv.org/abs/2411.02483v1 (pdf) |
| Date submitted: | 2024-11-06 18:27 |
| Submitted by: | Rodd, Nicholas |
| Submitted to: | SciPost Physics Community Reports |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
|
| Approaches: | Theoretical, Experimental, Phenomenological |
Abstract
In this note, we give a definitive basis for the dimension-eight operators leading to quartic -- but no cubic -- interactions among electroweak gauge bosons. These are often called anomalous quartic gauge couplings, or aQGCs. We distinguish in particular the CP-even ones from their CP-odd counterparts.
Current status:
Reports on this Submission
Report
The report presents a community effort to clarify - once and for all - the composition and properties of the basis of dimension 8 SMEFT operators that generate anomalous Quartic Gauge Couplings (aQGC), but no anomalous Triple Gauge Couplings (aTGC).
The phenomenology of such operators has been studied for a long time, and the ATLAS and CMS collaborations have been long using this formalism to search for anomalies in their measurements, in particular of Vector Boson Scattering processes.
The basis employed was corrected several times in the past years, and the CP properties were never established in a fully correct way, leading to multiple inconvenient changes of notation and updates of the corresponding Monte Carlo tools.
The results of this report, which is co-authored by members of all groups who have previously attempted to close the deal on the operator set, are therefore very welcome.
There is no doubt that this report fulfills all requirements for publication in this journal.
I did my best to cross-check the formulas presented, as the value of the report clearly hinges on them being correct and free from typesetting errors.
I only found a few minor points, that I kindly ask the authors to look into (hopefully one last time) before recommending the report for publication.
1- is a factor 1/2 missing in the definition of $O^M_4, O^M_5$?
ref [3] uses $\widehat{W}_{\mu\nu} = \frac{W^i_{\mu\nu} \tau^i }{2}$.
in $O^M_1$, for instance, the 1/4 coming from the two W partially cancels with a 2 from $tr(\tau^i \tau^j) = 2 \delta^{ij}$, but in $O^M_4, O^M_5$ there are no traces of the pauli matrices, so I'm not seeing how the 1/2 could go away
2- for the same reason, is a 1/4 missing in the definition of $O^M_7$?
3- of all operators, I couldn't understand the conversion of $O^M_7$ to the notation of refs [4,6].
using the pauli matrix relation $\tau^i \tau^j = \delta^{ij} + i \epsilon^{ijk} \tau^k$ and keeping the current normalization in the definition of $O^M_7$, I find:
$O^M_7 = O_1 ^{H^2W^2} - O_3^{H^2W^2}$
where the minus sign in the second term comes from relabeling $ijk\to kji$ and then taking $\epsilon^{kji}=-\epsilon^{ijk}$.
I'm not sure where the relative factor 2 could come from.
4- as a minor comment, for the sake of having all conventions spelled out, it would be useful to indicate the conventions adopted for the definition of dual field strength and for the covariant derivative sign in the monte carlo codes.
Recommendation
Ask for minor revision