Baryon non-invariant couplings in Higgs effective field theory

Abstract

The basis of leading operators which are not invariant under baryon number is constructed within the Higgs effective field theory. This list contains 12 dimension six operators, which preserve the combination B − L, to be compared to only 6 operators for the standard model effective field theory. The discussion of the independent flavour contractions is presented in detail for a generic number of fermion families adopting the Hilbert series technique.

ALPs effective field theory and collider signatures

“…The chiral effective Lagrangian HEFT [25][26][27][28][29][30][31]34,[63][64][65][66][67][68][69], which in the context of generic non-linear realisations of EWSB describes the interactions among SM gauge degrees of freedom, SM fermions and a light Higgs resonance, consists of all operators invariant under Lorenz and SM gauge symmetries and written in terms of the SM spectrum with the only exception of the Higgs doublet, whose four degrees of freedom are distributed in two separate sets. On the one side, a unitary matrix U(x) describes only the three SM wouldbe Nambu-Goldstone bosons [25,[70][71][72] -that become the longitudinal components of the gauge bosons after EWSB.…”

“…On the other side, the physical Higgs particle h is introduced as an independent field, a generic singlet of the SM with arbitrary couplings [25,[27][28][29]73]. For particular values of the latter parameters and correlations of the operator coefficients the usual SMEFT linear formulation would be recovered [28,31,32,34,[64][65][66][67][68][69][74][75][76].…”

Revisiting Minimal Lepton Flavour Violation in the light of leptonic CP violation

“…An alternative would be to considered a non-linear realisation and the corresponding effective Lagrangian dubbed HEFT [181][182][183][184][185][186]. In this context, however, a much larger number of operators should be taken into consideration and a slightly different phenomenology is expected [187][188][189][190][191][192][193][194][195][196]. The focus in this paper is on the linear EWSB realisation and therefore the HEFT Lagrangian will not be considered in what follows.…”

The minimal flavour violating axion

“…In order to reproduce the expected value of the EW VEV, v ≡ 245 GeV fixed through the W gauge boson mass, it is then necessary to invoke a large value of the Higgs quartic coupling λ, describing in this way a strongly interacting scenario with a non-linearly realised EWSB mechanism. This is an intriguing possibility, especially considering the recent interest in non-SM descriptions of the Higgs sector, such as composite Higgs models [87][88][89][90][91][92][93][94][95], dilaton models [96][97][98][99][100][101][102][103], or general effective Lagrangians [104][105][106][107][108][109][110][111][112][113][114][115][116][117][118][119][120][121]. In this letter, however, the traditional EWSB mechanism will be considered, and this requires to invoke a fine tuning: either there is cancellation between µ 2 and λ HΦ v 2 Φ , or λ HΦ is artificially small.…”