Gravitational waves as a probe of left-right symmetry breaking

Abstract

Left-right symmetry at high energy scales is a well-motivated extension of the Standard Model. In this paper we consider a typical minimal scenario in which it gets spontaneously broken by scalar triplets. Such a realization has been scrutinized over the past few decades chiefly in the context of collider studies. In this work we take a complementary approach and investigate whether the model can be probed via the search for a stochastic gravitational wave background induced by the phase transition in which SU (3) C × SU (2) L × SU (2) R × U (1) B−L is broken down to the Standard Model gauge symmetry group. A prerequisite for gravitational wave production in this context is a first-order phase transition, the occurrence of which we find in a significant portion of the parameter space. Although the produced gravitational waves are typically too weak for a discovery at any current or future detector, upon investigating correlations between all relevant terms in the scalar potential, we have identified values of parameters leading to observable signals. This indicates that, given a certain moderate fine-tuning, the minimal left-right symmetric model with scalar triplets features another powerful probe which can lead to either novel constraints or remarkable discoveries in the near future. Let us note that some of our results, such as the full set of thermal masses, have to the best of our knowledge not been presented before and might be useful for future studies, in particular in the context of electroweak baryogenesis.

Prospects of gravitational waves in the minimal left-right symmetric model

“…This is consistent with the findings in ref. [103]. The BPs BP1 and BP2 with H 0 3 mass below TeV-scale can produce GWs of order 10 −13 with frequency at around 0.1 Hz, far above the prospects of BBO and DECIGO.…”

“…In this work, we examine phase transitions in the LRSM and the resultant features of the corresponding GWs. Compared with the re-JHEP03(2021)267 cent and former study [103], the new things of this paper lie in the following aspects: (i) we have implemented the correct EW vacuum conditions [104] and set α 2 = 0 (α 2 is a quartic coupling in the scalar potential eq. (2.2)), (ii) we have taken into account more recent LHC experimental bounds, which are collected in table 1 and figure 1, (iii) we have found more general parameter space where the strong FOPT can occur and detectable GWs can be produced, and (iv) we have also explored the complementarity of GW probes of LRSM and the direct searches of the heavy (or light long-lived) particles in the LRSM at the high-energy colliders, and examined how the self couplings of SM Higgs can be affected in the LRSM.…”

Pati-Salam axion

“…Finally, in the presence of a strong first-order phase transition the Left-Right symmetry breaking can lead to the production of a stochastic gravitational wave background, that might leave its imprint on the gravitational wave spectrum of forthcoming space-based interferometers [115]. This can happen in some parameter space regions of the Left-Right symmetric scalar potential, resembling an approximate scale invariance [116]. The latter work focussed on Left-Right breaking scales close to the TeV scale, but in principle detectable gravitational wave signals might arise also for M LR TeV.…”

Probing electroweak phase transition with multi-TeV muon colliders and gravitational waves

“…In the Standard Model (SM), lattice calculations have shown that the EWPT is a smooth crossover [3][4][5]. However, the EWPT could be first-order (FO) in many new physics models beyond the SM (BSM), such as the real singlet extended SM (xSM) [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], two-Higgsdoublet model [21][22][23][24][25][26][27][28][29][30][31][32][33][34], left-right symmetric model [35,36], 1 Georgi-Machacek model [38] and composite Higgs models [39][40][41][42][43][44][45][46], etc. A FOEWPT can drive the early Universe out of thermal equilibrium, providing the essential environment for the electroweak baryogenesis (EWBG) mechanism [47][48][49], which explains the observed ...…”