diff --git a/Models/DarkMatter/DMDMMediatorVertex.cc b/Models/DarkMatter/DMDMMediatorVertex.cc
new file mode 100644
--- /dev/null
+++ b/Models/DarkMatter/DMDMMediatorVertex.cc
@@ -0,0 +1,62 @@
+// -*- C++ -*-
+//
+// This is the implementation of the non-inlined, non-templated member
+// functions of the DMDMMediatorVertex class.
+//
+
+#include "DMDMMediatorVertex.h"
+#include "ThePEG/Interface/ClassDocumentation.h"
+#include "ThePEG/EventRecord/Particle.h"
+#include "ThePEG/Repository/UseRandom.h"
+#include "ThePEG/Repository/EventGenerator.h"
+#include "ThePEG/Utilities/DescribeClass.h"
+#include "ThePEG/Persistency/PersistentOStream.h"
+#include "ThePEG/Persistency/PersistentIStream.h"
+#include "DMModel.h"
+
+using namespace Herwig;
+
+DMDMMediatorVertex::DMDMMediatorVertex() : cDMmed_(0.) {}
+
+IBPtr DMDMMediatorVertex::clone() const {
+  return new_ptr(*this);
+}
+
+IBPtr DMDMMediatorVertex::fullclone() const {
+  return new_ptr(*this);
+}
+
+void DMDMMediatorVertex::persistentOutput(PersistentOStream & os) const {
+  os << cDMmed_;
+}
+
+void DMDMMediatorVertex::persistentInput(PersistentIStream & is, int) {
+  is >> cDMmed_;
+}
+
+// The following static variable is needed for the type
+// description system in ThePEG.
+DescribeClass<DMDMMediatorVertex,FFVVertex>
+describeHerwigDMDMMediatorVertex("Herwig::DMDMMediatorVertex", "HwDMModel.so");
+
+void DMDMMediatorVertex::Init() {
+
+  static ClassDocumentation<DMDMMediatorVertex> documentation
+    ("The DMDMMediatorVertex class implements the couplnig of dark matter to the mediator.");
+
+}
+
+void DMDMMediatorVertex::setCoupling(Energy2 ,tcPDPtr aa,tcPDPtr,tcPDPtr) {
+  int iferm=abs(aa->id());
+  assert(iferm==52);
+  norm(cDMmed_);
+  left(1.);
+  right(1.);
+}
+
+void DMDMMediatorVertex::doinit() {
+  FFVVertex::doinit();
+  cDMModelPtr model = dynamic_ptr_cast<cDMModelPtr>(generator()->standardModel());
+  cDMmed_ = model->cDMmed();
+  addToList(52, 52, 32);
+}
diff --git a/Models/DarkMatter/DMDMMediatorVertex.h b/Models/DarkMatter/DMDMMediatorVertex.h
new file mode 100644
--- /dev/null
+++ b/Models/DarkMatter/DMDMMediatorVertex.h
@@ -0,0 +1,113 @@
+// -*- C++ -*-
+#ifndef Herwig_DMDMMediatorVertex_H
+#define Herwig_DMDMMediatorVertex_H
+//
+// This is the declaration of the DMDMMediatorVertex class.
+//
+
+#include "ThePEG/Helicity/Vertex/Vector/FFVVertex.h"
+
+namespace Herwig {
+
+using namespace ThePEG;
+
+/**
+ * The DMDMMediatorVertex class implements the coupling of the dark matter to the mediator
+ *
+ * @see \ref DMDMMediatorVertexInterfaces "The interfaces"
+ * defined for DMDMMediatorVertex.
+ */
+class DMDMMediatorVertex: public FFVVertex {
+
+public:
+
+  /**
+   * The default constructor.
+   */
+  DMDMMediatorVertex();
+  
+  /**
+   * Calculate the couplings. 
+   * @param q2 The scale \f$q^2\f$ for the coupling at the vertex.
+   * @param part1 The ParticleData pointer for the first  particle.
+   * @param part2 The ParticleData pointer for the second particle.
+   * @param part3 The ParticleData pointer for the third  particle.
+   */
+  virtual void setCoupling(Energy2 q2,tcPDPtr part1,tcPDPtr part2,tcPDPtr part3);
+
+public:
+
+  /** @name Functions used by the persistent I/O system. */
+  //@{
+  /**
+   * Function used to write out object persistently.
+   * @param os the persistent output stream written to.
+   */
+  void persistentOutput(PersistentOStream & os) const;
+
+  /**
+   * Function used to read in object persistently.
+   * @param is the persistent input stream read from.
+   * @param version the version number of the object when written.
+   */
+  void persistentInput(PersistentIStream & is, int version);
+  //@}
+
+  /**
+   * The standard Init function used to initialize the interfaces.
+   * Called exactly once for each class by the class description system
+   * before the main function starts or
+   * when this class is dynamically loaded.
+   */
+  static void Init();
+
+protected:
+
+  /** @name Clone Methods. */
+  //@{
+  /**
+   * Make a simple clone of this object.
+   * @return a pointer to the new object.
+   */
+  virtual IBPtr clone() const;
+
+  /** Make a clone of this object, possibly modifying the cloned object
+   * to make it sane.
+   * @return a pointer to the new object.
+   */
+  virtual IBPtr fullclone() const;
+  //@}
+
+
+protected:
+
+  /** @name Standard Interfaced functions. */
+  //@{
+  /**
+   * Initialize this object after the setup phase before saving an
+   * EventGenerator to disk.
+   * @throws InitException if object could not be initialized properly.
+   */
+  virtual void doinit();
+  //@}
+
+private:
+
+  /**
+   * The assignment operator is private and must never be called.
+   * In fact, it should not even be implemented.
+   */
+  DMDMMediatorVertex & operator=(const DMDMMediatorVertex &);
+
+private:
+
+  /**
+   * DM coupling to the dark mediator
+   */
+  double cDMmed_;
+
+};
+
+}
+
+#endif /* Herwig_DMDMMediatorVertex_H */
diff --git a/Models/DarkMatter/DMMediatorQuarksVertex.cc b/Models/DarkMatter/DMMediatorQuarksVertex.cc
new file mode 100644
--- /dev/null
+++ b/Models/DarkMatter/DMMediatorQuarksVertex.cc
@@ -0,0 +1,64 @@
+// -*- C++ -*-
+//
+// This is the implementation of the non-inlined, non-templated member
+// functions of the DMMediatorQuarksVertex class.
+//
+
+#include "DMMediatorQuarksVertex.h"
+#include "ThePEG/Interface/ClassDocumentation.h"
+#include "ThePEG/EventRecord/Particle.h"
+#include "ThePEG/Repository/UseRandom.h"
+#include "ThePEG/Repository/EventGenerator.h"
+#include "ThePEG/Utilities/DescribeClass.h"
+#include "ThePEG/Persistency/PersistentOStream.h"
+#include "ThePEG/Persistency/PersistentIStream.h"
+#include "DMModel.h"
+
+using namespace Herwig;
+
+DMMediatorQuarksVertex::DMMediatorQuarksVertex() {}
+
+IBPtr DMMediatorQuarksVertex::clone() const {
+  return new_ptr(*this);
+}
+
+IBPtr DMMediatorQuarksVertex::fullclone() const {
+  return new_ptr(*this);
+}
+
+void DMMediatorQuarksVertex::persistentOutput(PersistentOStream & os) const {
+  os << cSMmed_;
+}
+
+void DMMediatorQuarksVertex::persistentInput(PersistentIStream & is, int) {
+  is >> cSMmed_;
+}
+
+void DMMediatorQuarksVertex::setCoupling(Energy2 ,tcPDPtr aa,tcPDPtr,tcPDPtr) {
+  int iferm=abs(aa->id());
+  assert(iferm>0 && iferm<4);
+  norm(cSMmed_[iferm]);
+  left(1.);
+  right(1.);
+}
+
+// The following static variable is needed for the type
+// description system in ThePEG.
+DescribeClass<DMMediatorQuarksVertex,FFVVertex>
+  describeHerwigDMMediatorQuarksVertex("Herwig::DMMediatorQuarksVertex", "HwDMModel.so");
+
+void DMMediatorQuarksVertex::Init() {
+
+  static ClassDocumentation<DMMediatorQuarksVertex> documentation
+    ("The DMMediatorQuarksVertex class implements the coupling of the quarks to the mediator.");
+
+}
+
+void DMMediatorQuarksVertex::doinit() {
+  FFVVertex::doinit();
+  cDMModelPtr model = dynamic_ptr_cast<cDMModelPtr>(generator()->standardModel());
+  cSMmed_ = model->cSMmed();
+  for(int ix=1;ix<4;++ix) {
+    addToList(-ix, ix, 32);
+  }
+}
diff --git a/Models/DarkMatter/DMMediatorQuarksVertex.h b/Models/DarkMatter/DMMediatorQuarksVertex.h
new file mode 100644
--- /dev/null
+++ b/Models/DarkMatter/DMMediatorQuarksVertex.h
@@ -0,0 +1,111 @@
+// -*- C++ -*-
+#ifndef Herwig_DMMediatorQuarksVertex_H
+#define Herwig_DMMediatorQuarksVertex_H
+//
+// This is the declaration of the DMMediatorQuarksVertex class.
+//
+
+#include "ThePEG/Helicity/Vertex/Vector/FFVVertex.h"
+
+namespace Herwig {
+
+using namespace ThePEG;
+
+/**
+ * The DMMediatorQuarksVertex class implements the couplings of the quarks to the mediator 
+ *
+ * @see \ref DMMediatorQuarksVertexInterfaces "The interfaces"
+ * defined for DMMediatorQuarksVertex.
+ */
+class DMMediatorQuarksVertex: public FFVVertex {
+
+public:
+
+  /**
+   * The default constructor.
+   */
+  DMMediatorQuarksVertex();
+  
+  /**
+   * Calculate the couplings. 
+   * @param q2 The scale \f$q^2\f$ for the coupling at the vertex.
+   * @param part1 The ParticleData pointer for the first  particle.
+   * @param part2 The ParticleData pointer for the second particle.
+   * @param part3 The ParticleData pointer for the third  particle.
+   */
+  virtual void setCoupling(Energy2 q2,tcPDPtr part1,tcPDPtr part2,tcPDPtr part3);
+
+public:
+
+  /** @name Functions used by the persistent I/O system. */
+  //@{
+  /**
+   * Function used to write out object persistently.
+   * @param os the persistent output stream written to.
+   */
+  void persistentOutput(PersistentOStream & os) const;
+
+  /**
+   * Function used to read in object persistently.
+   * @param is the persistent input stream read from.
+   * @param version the version number of the object when written.
+   */
+  void persistentInput(PersistentIStream & is, int version);
+  //@}
+
+  /**
+   * The standard Init function used to initialize the interfaces.
+   * Called exactly once for each class by the class description system
+   * before the main function starts or
+   * when this class is dynamically loaded.
+   */
+  static void Init();
+
+protected:
+
+  /** @name Standard Interfaced functions. */
+  //@{
+  /**
+   * Initialize this object after the setup phase before saving an
+   * EventGenerator to disk.
+   * @throws InitException if object could not be initialized properly.
+   */
+  virtual void doinit();
+  //@}
+
+protected:
+
+  /** @name Clone Methods. */
+  //@{
+  /**
+   * Make a simple clone of this object.
+   * @return a pointer to the new object.
+   */
+  virtual IBPtr clone() const;
+
+  /** Make a clone of this object, possibly modifying the cloned object
+   * to make it sane.
+   * @return a pointer to the new object.
+   */
+  virtual IBPtr fullclone() const;
+  //@}
+
+private:
+
+  /**
+   * The assignment operator is private and must never be called.
+   * In fact, it should not even be implemented.
+   */
+  DMMediatorQuarksVertex & operator=(const DMMediatorQuarksVertex &);
+
+  /**                           
+   * SM couplings to the dark mediator
+   */
+  vector<double> cSMmed_;
+  //@}
+  
+};
+
+}
+
+#endif /* Herwig_DMMediatorQuarksVertex_H */
diff --git a/Models/DarkMatter/DMModel.cc b/Models/DarkMatter/DMModel.cc
--- a/Models/DarkMatter/DMModel.cc
+++ b/Models/DarkMatter/DMModel.cc
@@ -1,56 +1,70 @@
 // -*- C++ -*-
 //
 // This is the implementation of the non-inlined, non-templated member
 // functions of the DMModel class.
 //
 
 #include "DMModel.h"
 #include "ThePEG/Interface/ClassDocumentation.h"
+#include "ThePEG/Interface/Parameter.h"
+#include "ThePEG/Interface/ParVector.h"
 #include "ThePEG/EventRecord/Particle.h"
 #include "ThePEG/Repository/UseRandom.h"
 #include "ThePEG/Repository/EventGenerator.h"
 #include "ThePEG/Utilities/DescribeClass.h"
 #include "ThePEG/Persistency/PersistentOStream.h"
 #include "ThePEG/Persistency/PersistentIStream.h"
 
 using namespace Herwig;
 
-DMModel::DMModel() {}
+DMModel::DMModel() : cDMmed_(0.), cSMmed_({1.0,1.0,1.0}) {}
 
 IBPtr DMModel::clone() const {
   return new_ptr(*this);
 }
 
 IBPtr DMModel::fullclone() const {
   return new_ptr(*this);
 }
 
 void DMModel::persistentOutput(PersistentOStream & os) const {
+  os << cDMmed_ << cSMmed_;
 }
 
 void DMModel::persistentInput(PersistentIStream & is, int) {
+  is >> cDMmed_ >> cSMmed_;
 }
 
 
 // The following static variable is needed for the type
 // description system in ThePEG.
 DescribeClass<DMModel,BSMModel>
 describeHerwigDMModel("Herwig::DMModel", "HwDMModel.so");
 
 void DMModel::Init() {
 
   static ClassDocumentation<DMModel> documentation
     ("The DMModel class is designed to implement a simple dark matter model"
      " with fermionic dark matter and a vector mediator, "
      "as described in  arXiv:1911.11147",
      "The DMModel class is designed to implement a simple dark matter model"
      " with fermionic dark matter and a vector mediator, "
      "as described in \\cite{Plehn:2019jeo}",
      "\\bibitem{Plehn:2019jeo}"
      "T.~Plehn, P.~Reimitz and P.~Richardson,"
      "%``Hadronic Footprint of GeV-Mass Dark Matter,''"
      "arXiv:1911.11147 [hep-ph]."
      "%%CITATION = ARXIV:1911.11147;%%");
 
+  static Parameter<DMModel,double> interfacecDMmed
+    ("cDMmed",
+     "coupling of DM to dark mediator",
+     &DMModel::cDMmed_, 1.0, 0., 10., false, false, Interface::limited);
+
+  static ParVector<DMModel,double> interfacecSMmed
+    ("cSMmed",
+     "coupling of SM to dark mediator",
+     &DMModel::cSMmed_, -1 , 1.0 , -10. , 10. , false, false, Interface::limited);
+
 }
 
diff --git a/Models/DarkMatter/DMModel.h b/Models/DarkMatter/DMModel.h
--- a/Models/DarkMatter/DMModel.h
+++ b/Models/DarkMatter/DMModel.h
@@ -1,85 +1,116 @@
 // -*- C++ -*-
 #ifndef Herwig_DMModel_H
 #define Herwig_DMModel_H
 //
 // This is the declaration of the DMModel class.
 //
 
 #include "Herwig/Models/General/BSMModel.h"
+#include "DMModel.fh"
 
 namespace Herwig {
 
 using namespace ThePEG;
 
 /**
  * The DMModel class is designed to implement a simple dark matter mode
  * with fermionic dark matter and a vector mediator, as described in  arXiv:1911.11147 
  *
  * @see \ref DMModelInterfaces "The interfaces"
  * defined for DMModel.
  */
 class DMModel: public BSMModel {
 
 public:
 
   /**
    * The default constructor.
    */
   DMModel();
 
 public:
 
   /** @name Functions used by the persistent I/O system. */
   //@{
   /**
    * Function used to write out object persistently.
    * @param os the persistent output stream written to.
    */
   void persistentOutput(PersistentOStream & os) const;
 
   /**
    * Function used to read in object persistently.
    * @param is the persistent input stream read from.
    * @param version the version number of the object when written.
    */
   void persistentInput(PersistentIStream & is, int version);
   //@}
 
   /**
    * The standard Init function used to initialize the interfaces.
    * Called exactly once for each class by the class description system
    * before the main function starts or
    * when this class is dynamically loaded.
    */
   static void Init();
 
+public:
+
+  /**
+   *  Access to the couplings
+   */
+  //@{
+
+  /**
+   * DM coupling to the mediator
+   */
+  const double & cDMmed() const {return cDMmed_;}
+  
+  /**
+   *   The couplings of the quarks to the mediators
+   */
+  const vector<double> & cSMmed() const {return cSMmed_;}
+  //@}
+  
 protected:
 
   /** @name Clone Methods. */
   //@{
   /**
    * Make a simple clone of this object.
    * @return a pointer to the new object.
    */
   virtual IBPtr clone() const;
 
   /** Make a clone of this object, possibly modifying the cloned object
    * to make it sane.
    * @return a pointer to the new object.
    */
   virtual IBPtr fullclone() const;
   //@}
 
 private:
 
   /**
    * The assignment operator is private and must never be called.
    * In fact, it should not even be implemented.
    */
   DMModel & operator=(const DMModel &) = delete;
 
+private:
+
+  /**
+   * DM coupling to the dark mediator
+   */
+  double cDMmed_;
+
+  /**                                                                                                                                                       
+   * SM couplings to the dark mediator
+   */
+  vector<double> cSMmed_;
+
 };
 
 }
 
 #endif /* Herwig_DMModel_H */
diff --git a/Models/DarkMatter/Makefile.am b/Models/DarkMatter/Makefile.am
--- a/Models/DarkMatter/Makefile.am
+++ b/Models/DarkMatter/Makefile.am
@@ -1,16 +1,20 @@
 BUILT_SOURCES  = DM__all.cc
 CLEANFILES = DM__all.cc
 
 DM__all.cc : $(DIR_H_FILES) $(DIR_CC_FILES) Makefile
 	@echo "Concatenating .cc files into $@"
 	@$(top_srcdir)/cat_with_cpplines $(DIR_CC_FILES) > $@
 
 EXTRA_DIST = $(ALL_H_FILES) $(ALL_CC_FILES)
 
 DIR_H_FILES = $(addprefix $(srcdir)/,$(ALL_H_FILES))
 ALL_H_FILES = \
-DMModel.h DMModel.fh
+DMModel.h DMModel.fh \
+DMMediatorQuarksVertex.h \
+DMDMMediatorVertex.h
 
 DIR_CC_FILES = $(addprefix $(srcdir)/,$(ALL_CC_FILES))
 ALL_CC_FILES = \
-DMModel.cc
+DMModel.cc \
+DMMediatorQuarksVertex.cc \
+DMDMMediatorVertex.cc