%0 Journal Article %T Dilatonic states near holographic phase transitions %+ Laboratoire Charles Coulomb (L2C) %A Elander, Daniel %A Piai, Maurizio %A Roughley, John %< avec comité de lecture %J Phys.Rev.D %V 103 %P 106018 %8 2021 %D 2021 %Z 2010.04100 %R 10.1103/PhysRevD.103.106018 %K bound state: spectrum %K compactification: circle %K background: geometry %K tachyon: stability %K dimension: 6 %K critical phenomena %K supergravity %K duality: holography %K dilaton %Z Physics [physics]/High Energy Physics - Theory [hep-th] %Z Physics [physics]/High Energy Physics - Lattice [hep-lat] %Z Physics [physics]/High Energy Physics - Phenomenology [hep-ph]Journal articles %X The spectrum of bound states of special strongly coupled confining field theories might include a parametrically light dilaton, associated with the formation of enhanced condensates that break (approximate) scale invariance spontaneously. It has been suggested in the literature that such a state may arise in connection with the theory being close to the unitarity bound in holographic models. We extend these ideas to cases where the background geometry is non-AdS, and the gravity description of the dual confining field theory has a top-down origin in supergravity. We exemplify this programme by studying the circle compactification of Romans six-dimensional half-maximal supergravity. We uncover a rich space of solutions, many of which were previously unknown in the literature. We compute the bosonic spectrum of excitations, and identify a tachyonic instability in a region of parameter space for a class of regular background solutions. A tachyon only exists along an energetically disfavoured (unphysical) branch of solutions of the gravity theory; we find evidence of a first-order phase transition that separates this region of parameter space from the physical one. Along the physical branch of regular solutions, one of the lightest scalar particles is approximately a dilaton, and it is associated with a condensate in the underlying theory. Yet, because of the location of the phase transition, its mass is not parametrically small, and it is, coincidentally, the next-to-lightest scalar bound state, rather than the lightest one. %G English %2 https://hal.science/hal-02981258/document %2 https://hal.science/hal-02981258/file/PhysRevD.103.106018.pdf %L hal-02981258 %U https://hal.science/hal-02981258 %~ CNRS %~ L2C %~ MIPS %~ UNIV-MONTPELLIER %~ AMIDEX %~ ANR %~ UM-2015-2021