mila panduroviċ vinča institute of nuclear sciences,srbija
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Deep inside a proton - structure functions F2 for heavy flavors. Mila Panduroviċ Vinča Institute of Nuclear Sciences,Srbija. Q 2. The key to inner life of proton is so-called structure function. Q 2. Back in the old days …. - PowerPoint PPT PresentationTRANSCRIPT
Mila PanduroviċVinča Institute of Nuclear Sciences,Srbija
Deep inside a proton -structure functions F2 for heavy flavors
Back in the old days …
The key to inner life of proton is so-called structure function
So in order to see a most intimate life inside proton (heavy flavors) one should consider shooting the biggest available arrow
Q2 Q2
High Energy eP collisions
Neutral current Charged current
Characteristic variables
Virtuality
Bjorken scaling variable
Inelasticity
Photoproduction (p) Q2 < 1 GeV2
Low Q2 DIS : 1< Q2 < 100 GeV2
High Q2 DIS : Q2 > 100 GeV2
Kinematic regimes
2 p·qX=
Q2
Y= p·qp·k
Q2= - q2 = - (k-k’)2
Quark parton model (QPM)If the resolution with which the proton is probed is sufficiently fine ( large enough Q2 ) hadrons are viewed as being composed of a number of point-like constituents-partons
If |p|2»mp2 QPM interprets Deep
Inelastic Scattering as the elastic scattering of a e- (e+) from a single quark
The eP cross section is an incoherentsum of - individual eqi scatteringcross sections times the probability -fi(x) that quark qi is carrying fraction x of proton’s momentum
e
P
parton
e’
Inclusive DIS cross section
Inclusive NC DIS cross section of ep → eX depends on two independent kinematic variables (chosen to be) x and Q2
2πα2
xQ4 [ y2xF1 + (1-y)F2]
d2σNC
dxdQ2=
F1(x),F2(x) – proton structure functions are giving the probability fi(x)=qi(x)dx of finding a quark carrying fraction x of a proton’s momentum (weighted by the electric charge of a quark)
Deep Inelastic Scattering - DIS
F2(x)=2 ·x · F1(x)F2(x)= ei2· x·[qi(x)+ qi(x)]
i
What proton is made of …
Goal of the analysis
Measurement of the charm and beauty content in both low and high Q2 eP neutral current interactions and calculation of charm and beauty contributions F
2cc and
F2bb to the proton structure function
For this purpose the property of long lifetime of charm and beauty hadrons is exploited
Inclusive DCA Method
DCA Method is based on lifetime information of heavy hadrons – impact parameters δ~DCA are different for heavy and light quarks
DCA - Distance of Closest Approach
Tools - h1oo
H1CalcVertex
H1CentralTrack H1Selection
H1Vertex
H1CalcJet
? !
H1CentralTrack
H1SVFit
uds DJANGOcc, bb RAPGAP, CASCADEp X PHOJET
Data and MC
MONTE CARLO
All MC event samples are passed through H1 detector simulation program
DATA
CJC tracks
CST Tracks
CJC- CST track fit
CST Hits
HERA I Data
CJC tracks
CST Tracks
CJC- CST track fit
CST Hits
HERA II Data
FST tracks
Quark flavour separation
S1, S2,S3- significance of tracks with highest, second highest and
third highest absolute significance
To reduce the uncertainty due to resolution and suppress contribution from light quarks will be using “subtracted” significance distributions
ΔS=S+- S-
Signed impact parameterSignificance Error on DCA
S=
δσ(δ)
SORRY NO CAN
DO !
Adding this to CV
Plot anything please !!!H1PLOTTER
Very much Please The nicest Please
Total MC
udscb
- Data
Significance distributions
Fitting
Using the least squares simultaneous fit of the subtracted S1, S2 and S3 we are obtaining the scaling factors Pc, Pb and Pl
of the number of heavy and light quarksThe obtained fractions of heavy quarks are used to calculate the reduced cross section for interaction of heavy quarks c(b)
F2cc=cc+
y2
1+(1+y)2FLcc
Using this we obtain the structure functions for c ( or b)
NC(x,Q2)= xQ4
2·π·α [1+(1+y)2]d2σNC
dxdQ2
cc(x,Q2)= NC(x,Q2) Pc · NcMCgen
Pc · NcMCgen + Pb · Nb
MCgen+Pl · NlMCgen
BCC
SummaryStructure functions are inheritance which HERA is giving us for the future experiments
As we are going to“feed” that to LHC...
Coach : Ivanka Božoviċ-Jelisavčiċ advising: Paul Thompson, Tatsiana Klimkovich …
M. Panduroviċ, Vinča Institute of Nuclear Sciences, X talks, 18-19 october, 2007
LHC
I hope that is going to be the exact meal or …something or someone else is going to be served …