arXiv subjects

Mia West

Publications and source records attributed to Mia West.

7 recordsLinked to original sources

arXiv2026

Efficient Hamiltonian Truncation: Fast Matrix Construction and Quantum Krylov Diagonalization

Hamiltonian truncation offers a nonperturbative route to quantum field theory, yet its accuracy is limited by the rapid expansion of the truncated Hilbert space, which drives up computational cost. We tackle this bottleneck with a hybrid strategy that pairs classical and quantum algorithms: 1) we develop an efficient basis-generation scheme built on integer partitions; 2) we speed up the construction of the sparse Hamiltonian matrix using symmetry-aware algorithms; and 3) we explore quantum Krylov diagonalization as a route to the low-lying spectrum. Benchmarking against the free massive scalar and $\phi^4$ theories in two spacetime dimensions, we achieve substantial gains in the computational efficiency of Hamiltonian truncation and chart a path toward future quantum implementations.

quant-ph↗

arXiv2025

Gravitational Waves from Confining Dark Sectors with Self-Consistent Effective Potentials

In this work, we present a self-consistent prediction for the gravitational wave signal arising from confinement-induced phase transitions in hidden non-Abelian SU(N) gauge theories with F light flavors. To do this, we impose perturbativity and unitarity constraints on the thermal effective potential to identify the portion of parameter space that admits a reliable effective field theory description. We also include the Polyakov-loop-improved finite-temperature potential for both N=3 and N=4, where N is the number of dark colors, using an approximate computation of the mediating effects. We compute the resulting gravitational wave spectrum and delineate the regions of parameter space that remain phenomenologically viable after imposing theoretical consistency conditions. We find that these constraints make uncovering a stochastic background gravitational wave signal in this scenario more challenging, even for proposed future detectors.

hep-ph↗

arXiv2024

Walls, bubbles and doom -- the cosmology of HEFT

As experiment charts new territory at the electroweak scale, the enterprise to characterise all possible theories becomes all the more necessary. In the absence of new particles, this ambitious enterprise is attainable and has led to the Higgs Effective Field Theory (HEFT) as the most general characterising framework, containing the Standard Model Effective Field Theory (SMEFT) as a subspace. The characterisation of this theory space led to the dichotomy SMEFT vs. HEFT\SMEFT as the two possible realisations of symmetry breaking. The criterion to distinguish these two possibilities is non-local in field space, and phenomena which explore field space beyond the neighbourhood of the vacuum manifold are in a singular position to tell them apart. Cosmology allows for such phenomena, and this work focuses on HEFT\SMEFT, the less explored of the two options, to find that first order phase transitions with detectable gravitational wave remnants, domain wall formation and vacuum decay in the far, far distant future can take place and single out HEFT\SMEFT. Results in cosmology are put against LHC constraints, and the potential of future ground- and space-based experiments to cover parameter space is discussed.

hep-ph↗

arXiv2024

On the effective action for scalars in a general manifold to any loop order

Functional methods and a derivative expansion are employed for laying out a procedure to compute the effective action to any loop order, for scalar fields parametrising an arbitrary Riemannian manifold, while maintaining explicit field-space covariance. In this process, the geometric generalization of the LSZ reduction formula is presented. These results are of use in the characterization of effective field theories for electroweak symmetry breaking and extend a geometric perspective in field space beyond one loop.

hep-th↗

arXiv2024

Fractional-charge hadrons and leptons to tell the Standard Model group apart

The gauge group of strong and electroweak interactions in Nature could be any of the four that share the same Lie algebra, $SU(3)_c\times SU(2)_L\times U(1)_Y/Z_p\equiv G_p$ with $Z_p=\left\{Z_6,Z_3,Z_2,Z_1\right\}$. Each of these cases allows in its spectrum for the matter fields of the SM but also for new distinctive representations, e.g. under the assumption that $q_L$ possesses the minimum possible hypercharge in Nature, $G_p$ allows for particles with a multiple of $p\,e/6$ for electric charge. This letter discusses how these new possibilities in the spectrum could be used to tell the SM group apart.

hep-ph↗

arXiv2022

Using copies to improve precision in continuous-time quantum computing

In the quantum optimisation setting, we build on a scheme introduced by Young et al [PRA 88, 062314, 2013], where physical qubits in multiple copies of a problem encoded into an Ising spin Hamiltonian are linked together to increase the logical system's robustness to error. We introduce several innovations that improve this scheme significantly. First, we note that only one copy needs to be correct by the end of the computation, since solution quality can be checked efficiently. Second, we find that ferromagnetic links do not generally help in this "one correct copy" setting, but anti-ferromagnetic links do help on average, by suppressing the chance of the same error being present on all of the copies. Third, we find that minimum-strength anti-ferromagnetic links perform best, by counteracting the spin-flips induced by the errors. We have numerically tested our innovations on small instances of spin glasses from Callison et al [NJP 21, 123022, 2019], and we find improved error tolerance for three or more copies in configurations that include frustration. Interpreted as an effective precision increase, we obtain several extra bits of precision for three copies connected in a triangle. This provides proof-of-concept of a method for scaling quantum annealing beyond the precision limits of hardware, a step towards fault tolerance in this setting.

quant-ph↗

arXiv2022

On the road(s) to the Standard Model

Experimental measurements point at the Standard Model (SM) as the theory of electroweak symmetry breaking, but as we close in on our characterization the question arises of what limits in theory space lead to the SM. The class of theories with this property cannot be ruled out, only constrained to an ever smaller neighbourhood of the SM. In contrast, which class of theories do not posses this limit and can therefore potentially be ruled out experimentally? In this work we study both classes and find evidence to support the Standard Model Effective field theory being the single road to the Standard Model, theories that fall outside this class keeping a `minimum distance' from the SM characterized by a cut-off of at most $ 4πv/g_{\rm SM}$.

hep-ph↗