Joint Physics Analysis Center projects website

                                         
This project is supported by U.S. DOE, U.S. NSF, CONACYT, and PAPIIT-DGAPA

Differential Cross Section

We present the codes and the online webpage for the calculation of $\frac{d\sigma}{d\Omega}$, $P$, and $P \frac{d\sigma}{d\Omega}$ observables for the following reactions:
\begin{alignat}{6} K^-p\to K^-p \, , \,& K^-p\to\bar{K}^0n \, ,\, & K^-p\to\pi^0 \Lambda \, , \, & K^-p\to\pi^- \Sigma^+ \, ,\, & K^-p\to\pi^+ \Sigma^- \, , \; & K^-p\to\pi^0 \Sigma^0 \, . \notag \end{alignat}

Fortran Code

  • Differential Cross Section Fortran code and input: zip file
  • Contact person: Cesar Fernandez-Ramirez
  • Last update: September 2015
  • Zip File Content:
    • README file: README.tex and README.pdf
    • Fortran Source File: kndxsecef.f
    • Parameter files (contain the parameters for each partial wave):
      • parameters.s01.inp
      • parameters.p01.inp
      • parameters.p03.inp
      • parameters.d03.inp
      • parameters.d05.inp
      • parameters.f05.inp
      • parameters.f07.inp
      • parameters.g07.inp
      • parameters.s11.inp
      • parameters.p11.inp
      • parameters.p13.inp
      • parameters.d13.inp
      • parameters.d15.inp
      • parameters.f15.inp
      • parameters.f17.inp
      • parameters.g17.inp
    • Input File: file.inp

      • Example of input file (file.inp): 

              prk-toprok-
        1
        2.5
        0
        180
        100
      • The first line indicates the process, the options are:

        • $K^-p\to K^-p$:     prk-toprok-
        • $K^-p\to\bar{K}^0n$:     prk-toneuk0
        • $K^-p\to\pi^0 \Lambda$:     prk-tolapi0
        • $K^-p\to\pi^- \Sigma^+$:   prk-tos+pi-
        • $K^-p\to\pi^+ \Sigma^-$:   prk-tos-pi+
        • $K^-p\to\pi^0 \Sigma^0$:     prk-tos0pi0

      • The second line indicates the fixed kinematical variable, the options are:

        • $s$ (GeV$^2$):        1
        • $p_{lab}$ (GeV):     2
        • $E_{lab}$ (GeV):     3

        where $s$ is energy squared in the center of mass frame,
        and $p_{lab}$ and $E_{lab}$ are, respectively, the momentum and the energy of the incoming $K^-$ in the laboratory frame.

      • The third line indicates the value of fixed the kinematical variable.

      • The fourth line indicates the initial value of the angular range in degrees.

      • The fifth line indicates the final value of the angular range in degrees.

      • The sixth line indicates the the amount of points to calculate.
        There is a limit of 1000 points.
        It can be changed modifying variable max_data_points=1000 in module resonancesizes.

Online version

The online version of the code is the same as the one available for download except for some built-in functionalities aimed to allow the webpage to produce nicer plots.
The webpage has integrated some restrictions in the inputs through drop-down menus, kinematical ranges and number of points to calculate.
Depending on the kinematical variable used as input the available ranges are:

  • $s \in \left[2.1 , 5.0 \right]$ GeV$^2$
  • $p_{lab}\in \left[0.164 , 2.0 \right]$ GeV
  • $E_{lab}\in \left[0.52 , 2.07 \right]$ GeV
where $s$ is the energy squared in the center of mass frame,
and $p_{lab}$ and $E_{lab}$ are, respectively, the momentum and the energy of the incoming $K^-$ in the laboratory frame.
There is a limit of 1000 points to calculate.

Output

The online and the downloadable versions produce an output file (output.txt) which contains nine columns:

    (i)       $s$ (GeV$^2$),
    (ii)     $~E_{lab}$ (GeV),
    (iii)    $~p_{lab}$ (GeV),
    (iv)     the center of mass incoming momentum squared $q^2$ (GeV$^2$),
    (v)       angle (degrees),
    (vi)     cosine of the angle,
    (vii)    differential cross section in microbarn/sr,
    (viii)   $P\frac{d\sigma}{d\Omega}$ in microbarn/sr, and
    (ix)     $P$ asymmetry (adimensional).
The online version also produces three figures with the observables vs $\cos \theta$.

Run online version of the code

Select Reaction:

Select Kinematical Input: