When one has several vectors, and need to sort them simultaneously by one of them, one can contract a vector with the indices of the sorted entries.

#include <iostream>
#include <vector>
#include <utility>

using namespace std;

bool pairsort( const pair<float, int>& i, const pair<float, int>& j ) {
	if( i.first < j.first ) return false;
	if( j.first < i.first ) return true;
	return j.second < i.second;
}

vector<int>  sortmap(vector<float> org){
	vector< pair<float, int>  > p;	
	//create a pair <value, index>
	for(unsigned int i= 0; i!= org.size(); i++) {
		pair<float, int> a ( org.at(i), i);
		p.push_back( a );
	}
	
	sort(p.begin(), p.end(), pairsort);
	
	vector< int > ind;	
	//create a pair <value, index>
	for(unsigned int i= 0; i!= p.size(); i++) {
		ind.push_back( p.at(i).second );
	}
	return ind;
}


int main(){

 vector<float> Jet_pt;
 vector<float> Jet_eta;
 vector<float> Jet_phi;

 // Fill vectors...
 vector<int> m = sortmap(Jet_eta);
 cout << "Jets ordered by eta" << endl;
 for(int i = 0; i!= m.size(); i++)
   cout << i << " pt="<< Jets_pt.at(m.at(i))<< "eta="<< Jets_eta.at(m.at(i)) << endl;
 return 0;
}