Journal Club

Seminar Room

If you want to propose a paper, you can contact Supratim Das Bakshi (sdb AT

Monday 14th of November, 2016

Runaway Relaxion Monodromy

We examine the relaxion mechanism in string theory. An essential feature is that an axion winds over N1 fundamental periods. In string theory realizations via axion monodromy, this winding number corresponds to a physical charge carried by branes or fluxes. We show that this monodromy charge backreacts on the compact space, ruining the structure of the relaxion action. In particular, the barriers generated by strong gauge dynamics have height eN, so the relaxion does not stop when the Higgs acquires a vev. Backreaction of monodromy charge can therefore spoil the relaxion mechanism. We comment on the limitations of technical naturalness arguments in this context.
Comments: 1+45 pages, 4 appendices, 5 figures
Subjects: High Energy Physics - Theory (hep-th); High Energy Physics - Phenomenology (hep-ph)
Cite as: arXiv:1610.05320 [hep-th]
  (or arXiv:1610.05320v1 [hep-th] for this version)


R. Vega-Morales



Lattice QCD for Cosmology

We present a full result for the equation of state (EoS) in 2+1+1 (up/down, strange and charm quarks are present) flavour lattice QCD. We extend this analysis and give the equation of state in 2+1+1+1 flavour QCD. In order to describe the evolution of the universe from temperatures several hundreds of GeV to several tens of MeV we also include the known effects of the electroweak theory and give the effective degree of freedoms. As another application of lattice QCD we calculate the topological susceptibility (chi) up to the few GeV temperature region. These two results, EoS and chi, can be used to predict the dark matter axion's mass in the post-inflation scenario and/or give the relationship between the axion's mass and the universal axionic angle, which acts as a initial condition of our universe.
Comments: pdflatex, 40 figures; Section on experimental setups added, small corrections
Subjects: High Energy Physics - Lattice (hep-lat); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
Report number: DESY 16-105
Cite as: arXiv:1606.07494 [hep-lat]
  (or arXiv:1606.07494v2 [hep-lat] for this version)


Presented by A. Ayala