Himalaya

Himalaya calculates three-loop corrections of order O((αt + αb)*αs^2) to the MSSM CP-even Higgs mass matrix and to the quartic Higgs coupling λ in the DR'-bar scheme using the results of:

• R. V. Harlander, P. Kant, L. Mihaila and M. Steinhauser, Higgs boson mass in supersymmetry to three loops, Phys. Rev. Lett. 100 (2008) 191602, [0803.0672],

• P. Kant, R. V. Harlander, L. Mihaila and M. Steinhauser, Light MSSM Higgs boson mass to three-loop accuracy, JHEP 08 (2010) 104, [1005.5709].

Please refer to these papers as well as

• R. V. Harlander, J. Klappert and A. Voigt, Higgs mass prediction in the MSSM at three-loop level in a pure DR context, Eur.Phys.J. C77 (2017) no.12, 814, [1708.05720],

• R. V. Harlander, J. Klappert, A. D. Ochoa Franco and A. Voigt, The light CP-even MSSM Higgs mass resummed to fourth logarithmic order, Eur.Phys.J. C78 (2018) no.10, 874, [1807.03509]

• R. V. Harlander, J. Klappert, and A. Voigt, The light CP-even MSSM Higgs mass including N3LO+N3LL QCD corrections, Eur.Phys.J. C80 (2020) no.3, 186, [1910.03595]

when using Himalaya.

Requirements

Himalaya requires:

• C++ compiler
• FORTRAN compiler
• CMake >= 3.1
• Eigen3

Building Himalaya

Installation of dependencies

The required Eigen library can be installed using the package manager of your Linux distribution. On Debian/Ubuntu, for example, one may run:

sudo apt-get install libeigen3-dev

Alternatively, the Conan package manager can be used to install the dependencies:

mkdir -p build
cd build
conan install ..

Compilation of Himalaya

Himalaya uses CMake to generate files for build automation. To build Himalaya one should first create a separate build directory inside Himalaya's top directory. Afterwards, cmake should be called:

mkdir -p build
cd build
cmake ..

cmake will search for required dependencies on your system, see the previous section. If you want to use the dependencies installed by Conan (see above), you need to run instead:

cmake .. -DCMAKE_TOOLCHAIN_FILE=./conan_paths.cmake

After calling cmake the build directory contains all required build files. Assuming that GNU make is used, one can start the build by running

make

By default the example executable example is created from examples/example.cpp, which prints all loop corrections calculated by Himalaya for a given MSSM parameter point:

./example

Running Himalaya

When the build is complete, the libraries libDSZ and libHimalaya have been created. The latter must be linked to user-written programs to call the routines of Himalaya. The library libDSZ is optional and has to be linked in addition, if the program does not already incorporate the associated FORTRAN code of P. Slavich for the 2-loop corrections [hep-ph/0105096, hep-ph/0112177, hep-ph/0212132, hep-ph/0305127].

C++ interface

We present a brief step by step guide how to run Himalaya at the C++ level and obtain the three-loop corrections to the CP-even Higgs mass matrix in the MSSM in the DR'-bar scheme and the quartic Higgs coupling of the Standard Model in the MS-bar scheme.

First one has to include the header

#include "himalaya/HierarchyCalculator.hpp"

in the C++ file. The MSSM DR'-bar parameters must be stored in a Parameters object. Here, an example for the SPS1a benchmark point is given:

himalaya::Parameters pars;           // DR'-bar parameters struct
pars.scale = 4.67491329E+02;         // renormalization scale
pars.mu = 3.52600579E+02;            // mu parameter
pars.g3 = 1.09949966E+00;            // gauge coupling g3 SU(3)
pars.vd = 2.49832484E+01;            // VEV of down Higgs doublet
pars.vu = 2.43650538E+02;            // VEV of up Higgs doublet
pars.mq2 << 2.99793928E+05, 0, 0,
            0, 2.99792102E+05, 0,
            0, 0, 2.49327504E+05;    // soft-breaking squared left-handed squark mass parameters
pars.md2 << 2.78275669E+05, 0, 0,
            0, 2.78273780E+05, 0,
            0, 0, 2.74928741E+05;    // soft-breaking squared right-handed down-squark mass parameters
pars.mu2 << 2.80477426E+05, 0, 0,
            0, 2.80475621E+05, 0,
            0, 0, 1.80478484E+05;    // soft-breaking squared right-handed up-squark mass parameters
pars.Ad << 0, 0, 0,
           0, 0, 0,
           0, 0, -784.3356416708631; // trilinear down type squark-Higgs coupling matrix
pars.Au << 0, 0, 0,
           0, 0, 0,
           0, 0, -527.8746242245387; // trilinear up type squark-Higgs coupling matrix
pars.MA = 3.92960954E+02;            // Mass of the CP-odd Higgs
pars.MG = 5.88220143E+02;            // Mass of the Gluino
pars.MW = 8.04136643E+01;            // Mass of the W boson
pars.MZ = 9.06817306E+01;            // Mass of the Z boson 
pars.Mt = 1.52117491E+02;            // Mass of the top quark
pars.Mb = 2.42010269E+00;            // Mass of the bottom quark
pars.Mtau = 1.777;                   // Mass of the tau lepton

Afterwards one can create a HierarchyCalculator object for the chosen parameter point:

himalaya::HierarchyCalculator hc(pars);

To calculate the loop corrections in the DR'-bar scheme one needs to call:

// the boolean argument switches between corrections proportional to αt (false) or αb (true)
himalaya::HierarchyObject ho = hc.calculateDMh3L(false);

All information which has been gathered during the calculation will be stored in the returned HierarchyObject and can be accessed by member functions.

To extract the three-loop correction to the Higgs mass matrix one needs to call:

// returns a 2x2 matrix with the αt*αs^2 correction for the given parameter point
auto dMh3L = ho.getDMh(3);

To extract the three-loop correction to the quartic Higgs coupling λ of the Standard Model in the DR'-bar scheme in the convention of [1407.4081] one needs to call

double delta_lambda_3L = ho.getDLambda(3);

The three-loop shift to the MS-bar scheme, ocurring when the one- and two-loop corrections are expressed in terms of the Standard Model MS-bar strong gauge and top Yukawa couplings can be obtained by calling ho.getDLambdaDRbarPrimeToMSbarShift(3).

An uncertainty estimate of the calculated three-loop λ due to the truncation of the mass hierarchy expansions can be obtained by calling

double delta_lambda_3L_uncertainty = ho.getDLambdaUncertainty(3);

A full and detailed example can be found in examples/example.cpp.

Example:

#include "himalaya/HierarchyCalculator.hpp"
#include <iostream>
#include <cmath>

himalaya::Parameters setup_point(double MS, double tb, double xt)
{
   himalaya::Parameters pars;

   const double MS2 = MS*MS;
   const double Xt = xt*MS;
   const double beta = std::atan(tb);
   pars.scale = MS;
   pars.mu = MS;
   pars.g1 = 0.46;
   pars.g2 = 0.65;
   pars.g3 = 1.166;
   pars.vd = 246*std::cos(beta);
   pars.vu = 246*std::sin(beta);
   pars.mq2 << MS2, 0, 0,
               0, MS2, 0,
               0, 0, MS2;
   pars.md2 << MS2, 0, 0,
               0, MS2, 0,
               0, 0, MS2;
   pars.mu2 << MS2, 0, 0,
               0, MS2, 0,
               0, 0, MS2;
   pars.ml2 << MS2, 0, 0,
               0, MS2, 0,
               0, 0, MS2;
   pars.me2 << MS2, 0, 0,
               0, MS2, 0,
               0, 0, MS2;
   pars.Au << 0, 0, 0,
              0, 0, 0,
              0, 0, Xt + pars.mu/tb;
   pars.Ad << 0, 0, 0, 0, 0, 0, 0, 0, 0;
   pars.Ae << 0, 0, 0, 0, 0, 0, 0, 0, 0;
   pars.Yu << 0, 0, 0, 0, 0, 0, 0, 0, 0.862;
   pars.Yd << 0, 0, 0, 0 ,0 ,0 ,0 ,0, 0.133;
   pars.Ye << 0, 0, 0, 0, 0, 0, 0, 0, 0.101;
   pars.MA = MS;
   pars.M1 = MS;
   pars.M2 = MS;
   pars.MG = MS;

   pars.validate(true);

   return pars;
}

int main()
{
   const auto point = setup_point(2000., 20., std::sqrt(6.));
   himalaya::HierarchyCalculator hc(point);

   try {
      // calculate the 3-loop corrections O(α_t*α_s^2)
      const auto ho = hc.calculateDMh3L(false);

      // extract 2x2 matrix with three-loop O(αt*αs^2) corrections
      const auto dMh3L = ho.getDMh(3);
      // extract three-loop O(αt*αs^2) correction to λ (DR'-bar scheme)
      const double delta_lambda_3L_DR = ho.getDLambda(3);
      // extract uncertainty estimate
      const double delta_lambda_3L_uncertainty = ho.getDLambdaUncertainty(3);
      // convert to MS-bar scheme
      const double delta_lambda_3L_MS =
         delta_lambda_3L_DR + ho.getDLambdaDRbarPrimeToMSbarShift(3);

      std::cout << "Δλ(3-loop,DR') = " << delta_lambda_3L_DR
                << " +- " << delta_lambda_3L_uncertainty << '\n'
                << "Δλ(3-loop,MS) = " << delta_lambda_3L_MS
                << " +- " << delta_lambda_3L_uncertainty << '\n';
   } catch (const std::exception& e) {
      std::cerr << e.what() << '\n';
   }

   return 0;
}

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