Measurements of Higgs boson production and couplings in the four-lepton channel in pp collisions at center-of-mass energies of 7 and 8 TeV with the ATLAS detector

The final ATLAS Run 1 measurements of Higgs boson production and couplings in the decay channel H→ZZ∗→ℓ+ℓ−ℓ′+ℓ′−, where ℓ,ℓ′=e or μ, are presented. These measurements were performed using pp collision data corresponding to integrated luminosities of 4.5 fb−1 and 20.3 fb−1 at center-of-mass energies of 7 TeV and 8 TeV, respectively, recorded with the ATLAS detector at the LHC. The H→ZZ∗→4ℓ signal is observed with a significance of 8.1 standard deviations at 125.36 GeV, the combined ATLAS measurement of the Higgs boson mass from the H→γγ and H→ZZ∗→4ℓ channels. The production rate relative to the Standard Model expectation, the signal strength, is measured in four different production categories in the H→ZZ∗→4ℓ channel. The measured signal strength, at this mass, and with all categories combined, is 1.44 +0.40−0.33. The signal strength for Higgs boson production in gluon fusion or in association with tt¯ or bb¯ pairs is found to be 1.7 +0.5−0.4, while the signal strength for vector-boson fusion combined with WH/ZH associated production is found to be 0.3 +1.6−0.9.

Cheese whey: a cost-effective alternative for hyaluronic acid production by Streptococcus zooepidemicus

This study focuses on the optimization of cheese whey formulated media for the production of hyaluronic acid HA by Streptococcus zooepidemicus. Culture media containing whey (W; 2.1 g/L) or whey hydrolysate (WH; 2.4 g/L) gave the highest HA productions. Both W and WH produced high yields on protein consumed, suggesting cheese whey is a good nitrogen source for S. zooepidemicus production of HA. Polysaccharide concentrations of 4.0 g/L and 3.2 g/L were produced in W and WH in a further scale-up to 5 L bioreactors, confirming the suitability of the low-cost nitrogen source. Cheese whey culture media provided high molecular weight (> 3000 kDa) HA products. This study revealed replacing the commercial peptone by the low-cost alternative could reduce HA production costs by up to a 70%compared to synthetic media.

Study of (W/Z)H production and Higgs boson couplings using H -> WW* decays with the ATLAS detector

A search for Higgs boson production in association with a W or Z boson, in the H→ W W ∗ decay channel, is performed with a data sample collected with the ATLAS detector at the LHC in proton-proton collisions at centre-of-mass energies s√=7 TeV and 8 TeV, corresponding to integrated luminosities of 4.5 fb−1 and 20.3 fb−1, respectively. The WH production mode is studied in two-lepton and three-lepton final states, while two- lepton and four-lepton final states are used to search for the ZH production mode. The observed significance, for the combined W H and ZH production, is 2.5 standard deviations while a significance of 0.9 standard deviations is expected in the Standard Model Higgs boson hypothesis. The ratio of the combined W H and ZH signal yield to the Standard Model expectation, μ V H , is found to be μ V H  = 3.0 − 1.1 + 1.3 (stat.) − 0.7 + 1.0 (sys.) for the Higgs boson mass of 125.36 GeV. The W H and ZH production modes are also combined with the gluon fusion and vector boson fusion production modes studied in the H → W W ∗ → ℓνℓν decay channel, resulting in an overall observed significance of 6.5 standard deviations and μ ggF + VBF + VH = 1. 16 − 0.15 + 0.16 (stat.) − 0.15 + 0.18 (sys.). The results are interpreted in terms of scaling factors of the Higgs boson couplings to vector bosons (κ V ) and fermions (κ F ); the combined results are: |κ V | = 1.06 − 0.10 + 0.10 , |κ F | = 0. 85 − 0.20 + 0.26 .

Search for a new resonance decaying to a W or Z boson and a Higgs boson in the ℓℓ/ℓν/νν+bb¯final states with the ATLAS detector

A search for a new resonance decaying to a W or Z boson and a Higgs boson in the ℓℓ/ℓν/νν+bb¯ final states is performed using 20.3 fb−1 of pp collision data recorded at s√= 8 TeV with the ATLAS detector at the Large Hadron Collider. The search is conducted by examining the WH/ZH invariant mass distribution for a localized excess. No significant deviation from the Standard Model background prediction is observed. The results are interpreted in terms of constraints on the Minimal Walking Technicolor model and on a simplified approach based on a phenomenological Lagrangian of Heavy Vector Triplets.