ZPATH 2014 COMPARISONS TO ATLAS F OuldSaada et

Z-PATH 2014 COMPARISONS TO ATLAS F. Ould-Saada et al. , University of Oslo ‘H’ gg ‘H’ ZZ* llll

Invariant Mass – Overview of student results You have mastered the Invariant Mass concept and applied the technique to: Z J/y Z’ MC U Rediscover J/y, U, Z particles and measure their masses and decay widths Search for the Higgs boson (H) decaying to l+l- and gg Search for a new, exotic Z’ boson that would decay into l+l … in a similar way as ATLAS did z. Path@IMC 2014 2

Invariant mass M(l+l-): ATLAS vs. IMC students Z J/y U At the beginning of the LHC physics program, ATLAS rediscovered various standard model particles – J/y, U, Z, etc. – before seeking new phenomena Z’ MC You have found the J/y (~3 Ge. V), U (~10 Ge. V), and Z (~91 Ge. V) at the right masses! The Z’ signal at ~1 Te. V is Monte Carlo simulated ATLAS searches for such exotic particles z. Path@IMC 2014 3

Invariant mass M(l+l-): ATLAS vs. IMC students ATLAS status: � Is there any New Physics out there? For example a new weak interaction mediated by a Z’ boson? Z? : yes Z’? No – not yet �Z’ must be heavier than 2. 9 Te. V Z (data) m+m- Z (data) e+e- Z’ MC With the Invariant Mass technique you could Measure known particles Look for new hypothetical particles – Z’, exactly like ATLAS does z. Path@IMC 2014 4

Higgs search H 4 l ATLAS vs. IMC Students M(eemm)=123 Ge. V ATLAS results H ZZ* llll 25. 3 fb-1 You have searched for Higgs H llll with 2 fb-1 z. Path@IMC 2014 5

Higgs search H gg: ATLAS vs. IMC Students ATLAS results: H gg 25. 5 fb-1 clear signal You have searched for Higgs M(gg)=125 Ge. V H gg with 2 fb-1 You have several candidates at ~125 Ge. V You don’t have -1 enough statistics to With 25 fb , you would reproduce the ATLAS clearly observe a signal on top of a large result background. z. Path@IMC 2014 6