Journal Club

Seminar Room

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

Monday 17th of October, 2016

Relaxation from particle production

We consider using particle production as a friction force by which to implement a "Relaxion" solution to the electroweak hierarchy problem. Using this approach, we are able to avoid superplanckian field excursions and avoid any conflict with the strong CP problem. The relaxation mechanism can work before, during or after inflation allowing for inflationary dynamics to play an important role or to be completely decoupled.
Comments: 12 pages, 1 figures
Subjects: High Energy Physics - Phenomenology (hep-ph)
Cite as: arXiv:1607.01786 [hep-ph]
  (or arXiv:1607.01786v1 [hep-ph] for this version)


R. Vega-Morales


Cosmological Relaxation of the Electroweak Scale

A new class of solutions to the electroweak hierarchy problem is presented that does not require either weak scale dynamics or anthropics. Dynamical evolution during the early universe drives the Higgs mass to a value much smaller than the cutoff. The simplest model has the particle content of the standard model plus a QCD axion and an inflation sector. The highest cutoff achieved in any technically natural model is 10^8 GeV.
Comments: 10 pages, 2 figures. v2: We describe a way in which the bound on the cutoff in the QCD model can be raised to 1000 TeV. We've added a discussion of constraints on reheating. An additional constraint is noted for the non-QCD model. Other clarifications of the model added throughout
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
Journal reference: Phys. Rev. Lett. 115, 221801 (2015)
DOI: 10.1103/PhysRevLett.115.221801
Cite as: arXiv:1504.07551 [hep-ph]
  (or arXiv:1504.07551v2 [hep-ph] for this version)

R. Vega-Morales


Confronting SUSY models with LHC data via electroweakino production

We investigate multi-lepton signals produced by ElectroWeakino (EWino) decays in the MSSM and the TMSSM scenarios with sfermions, gluinos and non Standard Model Higgses at the TeV scale, being the Bino electroweak-scale dark matter. We recast the present LHC constraints on EWinos for these models and we find that wide MSSM and TMSSM parameter regions prove to be allowed. We forecast the number of events expected in the signal regions of the experimental multi-lepton analyses in the next LHC runs. The correlations among these numbers will help to determine whether future deviations in multi-lepton data are ascribable to the EWinos, as well as the supersymmetric model they originate from.
Comments: 33 pages, 10 figures, 3 tables
Subjects: High Energy Physics - Phenomenology (hep-ph)
Cite as: arXiv:1610.03822 [hep-ph]
  (or arXiv:1610.03822v1 [hep-ph] for this version)

Presented by M. Chala