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Concept

Effective action

Related publications (24)

The S-matrix bootstrap. Part III: higher dimensional amplitudes

João Miguel Augusto Penedones Fernandes, Jonathan Campbell Toledo

We consider constraints on the S-matrix of any gapped, Lorentz invariant quantum field theory in 3+1 dimensions due to crossing symmetry, analyticity and unitarity. We extremize cubic couplings, quartic couplings and scattering lengths relevant for the ela ...

Springer Nature2019

Sub-MeV dark matter and the Goldstone modes of superfluid helium

Angelo Esposito

We show how a relativistic effective field theory for the superfluid phase of 4 He can replace the standard methods used to compute the production rates of low-momentum excitations due to the interaction with an external probe. This is done by studying the ...

American Physical Society2019

Constraints on violation of Lorentz invariance from atmospheric showers initiated by multi-TeV photons

Sergey Sibiryakov

Parameterizing hypothetical violation of Lorentz invariance at high energies using the framework of effective quantum field theory, we discuss its effect on the formation of atmospheric showers by very-high-energy gamma rays. In the scenario where Lorentz ...

Iop Publishing Ltd2017

Excitation spectrum and density matrix renormalization group iterations

Frédéric Mila, Natalia Chepiga

We show that, in certain circumstances, exact excitation energies appear as locally site-independent (or flat) modes if one records the excitation spectrum of the effective Hamiltonian while sweeping through the lattice in the variational matrix-product-st ...

2017