This manual describes how to use the program
**HiggsPt**, which computes the Higgs boson
Transverse Momentum distribution at NLO in the
limit of large top quark mass. The manual gives
line-by-line instructions for the input file
"HiggsPt.indat".

It should be fairly easy to use the input file,
"HiggsPt.indat", just by modifying the example
that came with the source distribution. However, there are a few
general formatting requirements to be aware of.

The input file must have exactly 12 lines.

In the following explanations
of the inputs, a list **{a, b, c}** indicates a choice of string inputs
on a line, while an ordered list **[x y z]** indicates multiple numerical
parameters input on a single line. Possible inputs are colored
**red**.

If the input to a line
is a string, then it MUST have trailing white spaces after the string
(NOT TABS!). It is easiest to do this by keeping the explanatory
comment after the input string (i.e, white spaces followed by #x Comment)
from the example file.

Any input which is a string must be spelled exactly as given below,
including capitalization and without quotation marks, or else the program will
complain.

The program ignores anything in a line that comes after the expected input.

**#1 Name of the output file.**-
Any file name will do, such as
**output/HiggsPt.out**(without quotes). There is an empty directory "output/" in the same directory as the executable, which may be used for output files. Or you may organize as you desire. **#2 Type of collider.**-
Choose from {
**pp**,**ppbar**}. **#3 Collider COM energy**Input in GeV, such as **#4 PDF file name.**-
The file name (such as
**cteq6m.LHpdf**) for the particular PDF distribution to be used. The LHAPDF script "lhapdf-config" determines the correct path to the file, so make sure that the script is in the system $PATH. **#5 PDF member set.**-
This is an integer, which specifies the specific member set for the given
PDF distribution. The default of
**0**gives the "best fit" for any distribution. For more info, read the LHAPDF manual at http://projects.hepforge.org/lhapdf/. **#6 Choice of Ren/Fact Scale Variable.** Choose from {**#7 Input scale choices.**- The input format is
**[chiR chiF]**. For example,**1.0 1.0**.

The scale factors are defined by:

**#8 Order of Calculation.**- Choose from {
**LO_MT**,**LO**,**NLO**}.

These give the order of the cross section to be calculated. (To be precise,**NLO**computes the sum of order alpha_s^3 and order alpha_s^4 corrections here.) If**LO_MT**is chosen, then the full top quark mass dependence is included (only available at LO); otherwise, the cross section is calculated in the limit of infinite top quark mass. **#9 Limit of Calculation.**-
Choose from {
**EXACT**,**SMALLPT**}.

If**SMALLPT**is chosen, then calculate in the small-pt limit. **#10 Choice of distribution.** Choose from {**#11, #12 Distribution parameters.**- The input here depends on the specific distribution choice in line #10.

**PT**:**Line #11**-
Input the Higgs boson mass (in GeV) and rapidity:
**[M_Higgs, y_Higgs]**. For example,**120.0 0.0**. **Line #12**- Input the values for Higgs transverse momentum (in GeV):
**[ptmin ptstep ptnumber] = [Lowest value of pt, step size in pt, number of pt values - 1]**.

For example, an input of**30.0 20.0 10**would produce a distribution in Higgs pt, running from 30.0 GeV to 230.0 GeV, with a step size of 20.0 GeV.

**Y**:**Line #11**-
Input the Higgs boson mass and transverse momentum (in GeV):
**[M_Higgs, pt_Higgs]**. For example,**120.0 50.0**. **Line #12**- Input the values for Higgs rapidity:
**[ymin ystep ynumber] = [Lowest value of y, step size in y, number of y values - 1]**.

For example, an input of**0.0 0.5 8**would produce a distribution in Higgs rapidity from 0.0 to 4.0 with a step size of 0.5.

MH : |
muScale = M_H (Higgs Mass) |

MT : |
muScale = M_T = sqrt(M_H^2+p_T^2) (Higgs Transverse Mass) |

Renormalization : | mu_R=chiR*muScale. |

Factorization : | mu_F=chiF*muScale. |

PT : | Calculate the cross section as a function of Higgs Transverse momentum for fixed Higgs mass and Higgs rapidity. |

Y : | Calculate the cross section as a function of Higgs rapidity for fixed Higgs mass and Higgs transverse momentum. |