In the minimal left-right symmetric model which could accommodate the tiny neutrino masses via TeV seesaw mechanism, the neutral scalar from the right-handed symmetry breaking sector could be much lighter than the electroweak scale. We discuss the constraints on this particle from low-energy flavor observables, e.g. meson oscillations and rare decays, and find that such a light particle is necessarily long-lived, and can be searched for at the LHC via displaced signals of a collimated photon jet, if its mass is of order GeV scale.

An asymmetry between left- and right-chiral lepton states can induce

additional contributions to the electromagnetic current in the presence

of magnetic fields or vortical fluid flows. In contrast to the usual Ohmic

current these chiral currents are dissipationless. They can lead to instabilities

such as the chiral magnetic effect in which magnetic fields can undergo an

exponential growth phase, similar to the dynamo effect. We discuss astrophysical

and cosmological contexts in which such effects may play a role, such as

I will summarize the potential of the LISA mission to constrain the expansion history of the universe using massive black hole binary mergers as gravitational wave standard sirens. After briefly reviewing the concept of standard siren, I will outline the analysis and methodologies to use LISA as a cosmological probe, and present estimates for the power of LISA in constraining cosmological parameters for both standard and alternative cosmological models.

Most of the matter in our universe is in the form of dark matter. The research of the past decades led to the development of two canonical paradigms for its properties: the collisionless cold dark matter paradigm, supported by the observed gravitational clustering, and the WIMP paradigm, which provides a well-motivated particle physics framework for collisionless cold dark matter. However, current observational and experimental results motivate looking beyond these scenarios.

   Galileon models follow the Horndeski systematic construction to couple additional fields to gravity in order to modify the Einstein equations. There were first investigated from 2009 in the case of a single scalar field. Thus, there have been an increasing interest in similar models involving either a vector field or several scalar or vector fields. During this talk, I will present results from these different topics.