src/framework/JetScapeConstants.h

0001 /*******************************************************************************
0002  * Copyright (c) The JETSCAPE Collaboration, 2018
0003  *
0004  * Modular, task-based framework for simulating all aspects of heavy-ion collisions
0005  *
0006  * For the list of contributors see AUTHORS.
0007  *
0008  * Report issues at https://github.com/JETSCAPE/JETSCAPE/issues
0009  *
0010  * or via email to bugs.jetscape@gmail.com
0011  *
0012  * Distributed under the GNU General Public License 3.0 (GPLv3 or later).
0013  * See COPYING for details.
0014  ******************************************************************************/
0015
0016 #ifndef JETSCAPECONSTANTS_H
0017 #define JETSCAPECONSTANTS_H
0018
0019 namespace Jetscape {
0020
0021 // define the usual constants
0022 static double pi = 3.141592653589793;
0023
0024 static double nf = 3.0;
0025
0026 static double Cf = 4.0 / 3.0;
0027
0028 static double Tf = 0.5;
0029
0030 static double Ca = 3.0;
0031
0032 static double Nc = 3.0;
0033
0034 static double Lambda_QCD = 0.2;
0035 // 0.4 is the value chosen in JETSET
0036
0037 static const double hbarC = 0.197327053;
0038
0039 static const double fmToGeVinv = 1.0 / hbarC;
0040
0041 static double zeta3 = 1.20206;
0042
0043 static double mu = 0.722;
0044
0045 /* When the code becomes really accurate, a more accurate value for this can be used  */
0046
0047 /*  the following is the maximum value from the standard C++ random number generator */
0048 static double maxN = double(pow(2.0, 31.0) - 1.0);
0049
0050 static double a_very_large_number = maxN;
0051
0052 /* the following 2 lines control the error in the analytical part of the calculation. */
0053 /* Note analytical approximation, cannot be rectified by more statistics             */
0054 /* However, more accurate analytical calculation will require less statistics to obtain smooth distributions */
0055 /* the value is something for the user to choose based on his/her computing resources  */
0056
0057 static double error = 0.02;
0058
0059 static double approx = 0.02;
0060
0061 static double s_error = 0.01;
0062 static double s_approx = 0.01;
0063
0064 static double E_minimum = 1.0;
0065
0066 static double rounding_error = 1e-6; // slightly more than float precision
0067
0068 /**************************************************************************************/
0069
0070 /* the standard PDG particle id codes for the gluon and the d quark */
0071 static int gid = 21;
0072
0073 static int qid = 1;
0074
0075 static int uid = 2;
0076
0077 static int did = 1;
0078
0079 static int sid = 3;
0080
0081 static int cid = 4;
0082
0083 static int bid = 5;
0084
0085 static int photonid = 22;
0086
0087 static int Zid = 23;
0088
0089 static int Wid = 24; // refers to W+, use -24 for W-
0090 /*******************************************************************/
0091
0092 };     // namespace Jetscape
0093 #endif // JETSCAPECONSTANTS_H