EPS-HEP 2017

5-12 July 2017
Venice, Italy
Europe/Zurich timezone
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Searching for massless Dark Photons at LHC via Higgs boson production

6 Jul 2017, 17:30
15m
Room Welles (Palazzo del Casinò)

Room Welles

Palazzo del Casinò

Parallel Talk Higgs and New Physics

Speaker

Dr Barbara Mele (INFN)

Description

Dark photons $\bar{γ}$ mediating long-range forces in a dark sector are predicted by various new physics scenarios, and are being intensively searched for in experiments. Thanks to the non-decoupling properties of the Higgs boson, BR values of Higgs decaying into a photon plus darkphoton $H \to\gamma \bar{\gamma}$ up to a few percent are possible for a massless dark photon, even for heavy dark-sector scenarios. The corresponding signature consists (for a Higgs boson at rest) of a striking monochromatic photon with energy $E_{\gamma}=m_H/2$, and similar amount of missing energy. We perform a model independent analysis at the LHC of both the gluon-fusion and VBF Higgs production mechanisms at 14 TeV, including parton-shower effects, and updating our previous parton-level analysis at 8 TeV in the gluon-fusion channel by a more realistic background modeling. We find that a 5σ sensitivity can be reached in the gluon-fusion channel for $BR(H\to \gamma\bar{\gamma})≃0.1\%$ with an integrated luminosity of L≃300${\rm fb}^{−1}$. The corresponding VBF reach is instead restricted to 1%. Such decay rates can be naturally obtained in dark-photon scenarios arising from unbroken $U(1)_F$ models explaining the origin and hierarchy of the Yukawa couplings, strongly motivating the search for this exotic Higgs decay at the LHC.

Primary authors

Dr Emidio Gabrielli (University of Trieste) Dr Sanjoy Biswas (KIAS) Dr Matti Heikinheimo (Helsinki Institute of Physics) Dr Barbara Mele (INFN)