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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 $SU(3)_C \times SU(2)_L
\times SU(2)_R \times U(1)_{B-L}$ 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.