Status Analysis pp -> D s D s0 (2317) Overview Reconstruction Some QA plots Figure of merit First approach/strategy

Channel GeV) Decay Tree 8 final state particles Different options: –exclusive reconstruction –inclusive reconstruction via missing mass 70k Signal events, no PID no bkg events so far....

QA plots (Fast Reco, exclusive) N =  = 16.8 MeV N =  = 8.2 MeV N =  = 3.7 MeV N = 9923  = 12.4 MeV

Missing mass (exclusive) Instead of full reco of D sJ calculate the missing mass of D s to beam 4-vector  resolution improves from 12 MeV to 9 MeV! N =  = 9.2 MeV

m miss vs m Ds The both masses m miss and m Ds are highly correlated When we project to red line, we can gain much resolution! most likely from m miss for the wrong of the 2 D s

Sum m miss + m Ds N =    = 1.5 MeV   = 4.7 MeV All these results are without PID! We‘ll see, how much that will improve!

Figure of merit Reconstruction of decay channel (in data for each energy) –find efficiency, background sources and levels Assumption about X-section  –N=Lumi   Weight/distribute via excitation function Fit with the same function and extract –  (D sJ )   Repeat the procedure for –various  ‘s –various beam jitters –different total cross sections Figure of merit: For a given beam jitter and , we need N events to measure  with significance 3 

Excitation function pp  XX for resonance X with parameters m R = mass,  = width This has to be convoluted with a gaussian to take into account finite beam spread For our channel pp  D s D sJ we need modification of this formula; but for the moment is sufficient

Excitation function pp  XX with gaussian convolution (beam spread) dp/p=10 -5 dp/p=10 -4 dp/p=10 -3  = 1MeV  = 0.1MeV  = 0.01MeV

Sensitivity for extracing  Idea: –choose , number of signal N and number of flat bkg B –create histogram with this distribution –fit again the function to this histogram –extract     –Significance of measurement is  –(this has to be extended for different beam spreads!) Example:  =  MeV S = 8.6   = 1 MeV N = B = 0

Sensitivity cont‘d (  = 1 MeV) N = 1000 B = 0 S = 2.7  N = 1000 B = 1000 S = 1.3  N = B = 0 S = 8.6  N = B = S = 4.0 

Sensitivity cont‘d (  = 0.5 MeV) N = 1000 B = 0 S = 3.2  N = 1000 B = 1000 S = 0.8  N = B = 0 S = 6.5  N = B = S = 1.3 

Sensitivity cont‘d (  = 0.1 MeV) N = B = 0 S = 3.2  N = B = 1000 S = 0.93  N = B = 0 S = 12  N = B = S = 3.3 

Steps to do... With simulation determine efficiency and signal-to-noise When absolute cross section for bkg is known –calculate with efficiency the necessary signal cross section to measure  with 3  (for a set ,  p/p and integrated luminosity L) Open questions: –how to get by bkg level / bkg cross section –is DPM good enough to do that job –do we have to identify particular bkg channels? (do we know cross sections for those?)