1. Particle Physics Tour with CalcHEPby
Shymaa M. Seif
Assistant lecturer in Physics Department
Cairo University, Egypt
Supervision:
Dr. A. Glayshev
A. Bednyakov 1

2. CalcHEP
CalcHEP package is created for calculation of decay and high energy collision processes of elementary particle in tree approximation.
The mean idea of CalcHEP is to make available passing from the Lagrangian to the final distribution effectively, with high level of automatization. 2

3. Some useful features CalcHEP
You can restrict/specify the particle that enter the intermediate state.
CalcHEP provides a menu of structure functions, including CTEQ6 series which can be used to help compute pp scattering processes.
You can apply cuts before computing cross sections, sometimes this is necessary to remove divergences.
CalcHEP can perform calculations in various SUSY models; this is require CERNLIB
Limit on number of external legs (involved particles) and number of diagrams 3

4. CalcHEP SM Particles 4

5. CalcHEP SM Parameters 5

6. CalcHEP SM Constraints6

7. CalcHEP SM Vertices 7

8. Switch on External Libraries8

9. Particle content of CalcHEP9

10. CalcHEP limitations No Hadronic bound state. No loop o box diagrams.
All processes are averaged over allowed initial-state spin polarizations and summed over final-state polarization.
No neutrino oscillations. 10

11. Procedure for computing results
Specify decay or scattering process
View diagrams; can be written in latex, can delet selected diagrams
Square diagrams (can view)
Symbolic calculations
Write results
C code
C-compiler
Go to new window for numerical calculations
Select subprocess if applicable
Define cuts if desired
Vegas (Simpson if applicable)
Set distributions and ranges if desired
Integrate (2 < 1 for numerically consistent result)
View distribution
Generate events if desired 11

12. Setting Model Parameters
I have studied the dependence of the total cross section on the mass of light Higgs mass for the tree level process
in mSUGRA.
The model parameters were set:
tanβ=10, μ >1, m0 = –A0 =100 GeV and m1/2 =250 GeV.
and the SM parameters had taken as
ew(MZ)-1 = , mW = GeV, mZ = GeV,
mt =175 GeV, mb =4.62 GeV 12

13. control of the initial states and parton density functions
The structure function (PDF) for the proton is CTEQ6l
The momenta for both protons = 7000 GeV
The cuts
M0  30 GeV, m >176 GeV, m >173GeV,
The momenta for both protons = 7000 GeV such that s =14 TeV 13

14. LO Feynman Diagrams for14

15. LO Feynman Diagrams for15

16. Comparison between cross-sections
Mh (GeV)
σ (fb)
μ = μ0
μ = 4μ0 95
0.3482
0.2363
100
0.3314
0.2163
105
0.3117
0.2035
110
0.2961
0.1943
115
0.2755
0.1826
120
0.2594
0.1746
125
0.2466
0.1625
130
0.2337
0.1484
Table 1
Table 2 16

17. 17

18. 18