arXiv subjects

Coenraad Marinissen

Publications and source records attributed to Coenraad Marinissen.

7 recordsLinked to original sources

arXiv2026

Jet functions for next-to-leading power factorization

We discuss the factorization of scattering processes near partonic threshold at next-to-leading power (NLP) in the threshold variable $1-z$, with $z \equiv q^2/\hat{s}$. We review the general structure of power-suppressed contributions both in Soft-Collinear Effective Theory (SCET) and in a direct QCD approach, and discuss the definition of NLP jet functions as gauge-invariant operator matrix elements in QCD. As a controlled check of the resulting factorization formula, we verify it explicitly at one and two loops for the massive electromagnetic form factor in the limit $m^2 \ll s$, using the method of regions. We conclude by outlining the two challenges that remain for a systematic resummation of NLP logarithms: the treatment of endpoint divergences in SCET convolutions, and the extension of jet functions to radiative processes capable of describing an arbitrary number of soft-gluon emissions -- the latter being the last missing ingredient for exponentiation, given that the purely soft sector is already understood in terms of generalised webs via the replica trick.

hep-ph↗

arXiv2025

Catalogues of Cosmologically Self-Consistent Hadronic QCD Axion Models

We extend the catalogue of "phenomenologically preferred" hadronic axion models to include heavy fermion representations associated with higher-dimensional decay operators. The latter have recently been shown to self-consistently trigger a period of early matter domination, making the underlying axion models cosmologically viable. After identifying all possible representations up to decay operator dimension $d \leq 9$, we update the hadronic axion band for the axion-photon coupling. The central regions of the axion band are similar to those found previously and approximately independent of the axion decay constant $f_a$, suggesting that they are robust predictions and targets for future axion searches. Moreover, we find that $d = 6$ and $d = 7$ operators can lead to two new viable "model islands" around $f_a \sim 10^{12}$ GeV and $f_a \sim 10^{14}$ GeV, i.e., beyond the standard post-inflationary mass region.

hep-ph↗

arXiv2025

Next-to-leading power jet functions in the small-mass limit in QED

We investigate the factorization properties of the massive fermion form factor in QED, to next-to-leading power in the fermion mass, and up to two-loop order. For this purpose we define new jet functions that have multiple connections to the hard part as operator matrix elements, and compute them to second order in the coupling. We test our factorization formula using these new jet functions in a region-based analysis and find that factorization indeed holds. We address a number of subtle aspects such as rapidity regulators and external line corrections, and we find an interesting sequence of relations among the jet functions.

hep-ph↗

arXiv2024

Region analysis of QED massive fermion form factor

We perform an analysis of the one- and two-loop massive quark form factor in QED in a region expansion, up to next-to-leading power in the quark mass. This yields an extensive set of regional integrals, categorized into three topologies, against which factorization theorems at next-to-leading power could be tested. Our analysis reveals a number of subtle aspects involving rapidity regulators, as well as additional regions that manifest themselves only beyond one loop, at the level of single diagrams, but which cancel in the form factor.

hep-ph↗

arXiv2024

Resurgence of large order relations

One of the main applications of resurgence in physics is the decoding of nonperturbative effects through large order relations. These relations connect perturbative asymptotic expansions of observables to expansions around other saddle points. Together, this data is unified in transseries that describe the nonperturbative structure. It is known that large order relations themselves also take the form of transseries. We study these large order transseries, uncover an interesting underlying geometry that we call the `Borel cylinder', and show that large order transseries in turn are resurgent -- that is: their nonperturbative sectors `know about each other' through Borel residues that are essentially equal to those of the original transseries. We show that with an appropriate resummation prescription, large order relations are often exact: they can be used to exactly compute perturbative coefficients -- not just their large order growth. Finally, we argue that Stokes phenomenon plays an important role for large order relations, for example if we want to extend the discrete index of the perturbative coefficients to arbitrary complex values.

hep-th↗

arXiv2023

Discrete symmetries and Efficient Counting of Operators

We present DECO ("Discrete and Efficient Counting of Operators"), an implementation of the Hilbert Series to enumerate subleading operator bases for SMEFT-like EFTs with symmetry groups as typically found in flavour and BSM physics. DECO can accommodate EFTs with arbitrary numbers and combinations of the SM gauge groups, as well as the discrete groups S4, A4, and Zn, and U(1) groups with residual global charge (and these groups' most important representations). The program is highly modular and can easily be extended to additional groups and/or representations. We demonstrate the design cases for DECO by using it to cross-check subleading operator bases of EFTs in the literature, which allows us to identify a missing operator in a widely used model for the neutrino masses and discuss said operator's impact.

hep-ph↗

arXiv2023

Resurgence analysis of the Adler function at order $1/N_f^2$

We compute non-perturbative contributions to the Adler function, the derivative of the vacuum polarization function in gauge theory, using resurgence methods and Borel-summed gauge field propagators. At 2-loop, to order $1/N_f$, we construct the full 2-parameter transseries and perform the sum over the non-perturbative sectors. We then introduce a convolution-based method to derive the transseries structure of product series, which can also be used to study higher orders in the expansion in $1/N_f$. We compute 3-loop planar diagrams, at order $1/N_f^2$, and for each diagram study the asymptotic behavior and resulting non-perturbative information in the transseries. A structure emerges that, from a resurgence point of view, is quite different from toy models hitherto studied. We study in particular the first and second non-perturbative sectors, their relation to UV and IR renormalons, and how their presence influences the perturbative expansions in neighbouring sectors. Finally, finding that many non-perturbative sectors have asymptotic series, we derive relations among all of them, thus providing an interesting new perspective on the alien lattice for the Adler function.

hep-ph↗