Journal Club

Seminar Room

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

Thursday 1st of March, 2018

Supersymmetric Flaxion

Recently, a new minimal extension of the Standard Model has been proposed, where a spontaneously broken, flavor-dependent global U(1) symmetry is introduced. It not only explains the hierarchical flavor structure in the quark and lepton sector, but also solves the strong CP problem by identifying the Nambu-Goldstone boson as the QCD axion, which we call flaxion. In this work, we consider supersymmetric extensions of the flaxion scenario. We study the CP and flavor violations due to supersymmetric particles, the effects of R-parity violations, the cosmological gravitino and axino problems, and the cosmological evolution of the scalar partner of the flaxion, sflaxion. We also propose an attractor-like inflationary model where the flaxion multiplet contains the inflaton field, and show that a consistent cosmological scenario can be obtained, including inflation, leptogenesis, and dark matter.
Comments: 30 pages, 2 figures
Subjects: High Energy Physics - Phenomenology (hep-ph)
Report number: UT-18-1, IPMU18-0036
Cite as: arXiv:1802.07739 [hep-ph]
  (or arXiv:1802.07739v1 [hep-ph] for this version)

Presented by Mar B

Rare $Z$ Boson Decays to a Hidden Sector

We demonstrate that rare decays of the Standard Model $Z$ boson can be used to discover and characterize the nature of new hidden-sector particles. We propose new searches for these particles in soft, high-multiplicity leptonic final states at the Large Hadron Collider. The proposed searches are sensitive to low-mass particles produced in $Z$ decays, and we argue that these striking signatures can shed light on the hidden-sector couplings and mechanism for mass generation.
Comments: 10 pages, 5 figures. Updated figures with the corrected public LHCb limit table. Version submitted to PRD
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
Journal reference: Phys. Rev. D 97, 015009 (2018)
DOI: 10.1103/PhysRevD.97.015009
Report number: SLAC-PUB-17159
Cite as: arXiv:1710.07635 [hep-ph]
  (or arXiv:1710.07635v2 [hep-ph] for this version)

Presented by Roberto VM

Future DUNE constraints on EFT

In the near future, fundamental interactions at high-energy scales may be most efficiently studied via precision measurements at low energies. A universal language to assemble and interpret precision measurements is the so-called SMEFT, which is an effective field theory (EFT) where the Standard Model (SM) Lagrangian is extended by higher-dimensional operators. In this paper we investigate the possible impact of the DUNE neutrino experiment on constraining the SMEFT. The unprecedented neutrino flux offers an opportunity to greatly improve the current limits via precision measurements of the trident production and neutrino scattering off electrons and nuclei in the DUNE near detector. We quantify the DUNE sensitivity to dimension-6 operators in the SMEFT Lagrangian, and find that in some cases operators suppressed by an O(30) TeV scale can be probed. We also compare the DUNE reach to that of future experiments involving atomic parity violation and polarization asymmetry in electron scattering, which are sensitive to an overlapping set of SMEFT parameters.
Comments: 23 pages, 4 figures
Subjects: High Energy Physics - Phenomenology (hep-ph)
Report number: LPT-Orsay-18-19,
Cite as: arXiv:1802.08296 [hep-ph]
  (or arXiv:1802.08296v1 [hep-ph] for this version)

Presented by José S