Shawn Hayes Cohorts: Tianqi Tang, Molly Herman Higgs Analysis for CLIC at 380 GeV simulations

Objective Determine the precision with which we can measure the Higgs Mass and the cross section of the Higgs Strahlung process at 380 GeV Have Fun!

We followed the procedure of J.S. Marshall who performed a similar analysis at 350 GeV His Results I investigated the muon channel 350 GeV Muon channel Mean ∆M H MeV ∆N Sig 4.91 % 350 GeV Electron Channel Mean ∆M H MeV ∆N Sig 8.08 %

Philipp Roloff provided us with approximately signal (Higgs strahlung), and background events, simulated in WHIZARD. Assuming an integrated luminosity of 500 fb -1 it was necessary to apply weights to the events. We use cross section of 3.94 fb for our signal (Higgsstrahlung)and fb for our background (ee to mu,mu,f,f) to determine these weights. SignalBackGround Initial Events Weighted Events

First we graph some quantities we can measure from the muon pairs events From these we can perform a background rejection

More Variables

Use TMVA for Background Rejection TMVA is a multivariate analysis toolkit which we can use to perform optimal background rejection We input our variables (excluding recoil mass, for that’s the value we’re interested in) and through a Boosted Decision Tree process the TMVA determines the optimal cut to maximize signal significance Note that before the BDT process we apply some non-invasive precuts motivated by our histograms This greatly improved BDT performance Precuts: Transverse momentum > 20 GeV 120 GeV > Invariant mass > 50 GeV

Fitting We split our events into two parts One part we use to find the shape of the signal and background (recoil masses)by fitting them individually The second part we use a sum of these two fit functions to fit the total

From the parameters of the fit function we can extrapolate the signal and background functions after fitting the total Results from fit ∆N sig = 2.12 % ∆M H =365.3 MeV

Toy Monte Carlo Fitting After we perform the fit we wish to extract the precision of the measurement In order to attain a better idea of these values we perform the fit many times on Gaussian smeared histograms This is akin to doing the experiment many times

Here we have graphed the parameters of these fits. The sigmas of the Gaussian fits is the uncertainty of the measuremement

Results 380 GeV muon channel350 GeV muon channel (old study) ∆M H MeV133.3 MeV ∆N sig 3.00%4.91%