void reaction_virtual_LBL(void)
{
	TCanvas *c1 = new TCanvas("c1");
	c1->Range(-1.0, -1.0, +1.0, +1.0);
	
	gStyle->SetLineWidth(6);
	
	TArrow *electron_initial = new TArrow(-0.75, +0.75, -0.1, +0.3, 0.05, "->-");
	electron_initial->Draw();
	
	TArrow *positron_initial = new TArrow(-0.75, -0.75, -0.1, -0.3, 0.05, "->-");
	positron_initial->Draw();
	
	TArrow *electron_final = new TArrow(-0.1, +0.3, +0.75, +0.75, 0.05, "->");
	electron_final->Draw();
	
	TArrow *positron_final = new TArrow(-0.1, -0.3, +0.75, -0.75, 0.05, "->");
	positron_final->Draw();
	
	TArrow *pip = new TArrow(0.0, 0.0, 0.75, +0.30, 0.05, "->");
	pip->Draw();

	TArrow *pim = new TArrow(0.0, 0.0, 0.75, -0.30, 0.05, "->");
	pim->Draw();

	TCurlyLine *gamma1 = new TCurlyLine(-0.1, +0.3, 0.0, 0.0);
	gamma1->SetWavy();
	gamma1->SetWaveLength(0.03);
	gamma1->Draw();	
	TCurlyLine *gamma2 = new TCurlyLine(-0.1, -0.3, 0.0, 0.0);
	gamma2->SetWavy();
	gamma2->SetWaveLength(0.03);
	gamma2->Draw();
	
	
	TLatex t;
	t.SetTextSize(0.2);

	t.DrawLatex(-0.97, +0.70, "#it{e}^{-}");
	t.DrawLatex(+0.77, +0.70, "#it{e}^{-}");
	t.DrawLatex(-0.97, -0.92, "#it{e}^{+}");
	t.DrawLatex(+0.77, -0.95, "#it{e}^{+}");

	t.DrawLatex(0.77, +0.27, "#pi^{+}");
	t.DrawLatex(0.77, -0.38, "#pi^{-}");

	t.SetTextSize(0.12);
	t.DrawLatex(-0.239, +0.089, "#gamma*");
	t.DrawLatex(-0.220, -0.18, "#gamma*");
	
	c1->SaveAs("reaction_virtual_LBL.png");
	c1->SaveAs("reaction_virtual_LBL.pdf");
}

void AddMiddleArrowHead(TCurlyLine *cl)
{
	double xmid = (cl->GetStartX() + cl->GetEndX())/2.0;
	double ymid = (cl->GetStartY() + cl->GetEndY())/2.0;
	double dX = (cl->GetEndX() - cl->GetStartX())/1000.0;
	double dY = (cl->GetEndY() - cl->GetStartY())/1000.0;
	
	xmid += 10.0*dX;
	ymid += 10.0*dY;

	TArrow *arrow = new TArrow(xmid, ymid, xmid+dX, ymid+dY, 0.05, "->-");
	arrow->Draw();
}

void AddEndArrowHead(TCurlyLine *cl)
{
	double xend = cl->GetEndX();
	double yend = cl->GetEndY();
	double dX = (cl->GetEndX() - cl->GetStartX())/1000.0;
	double dY = (cl->GetEndY() - cl->GetStartY())/1000.0;
		
	TArrow *arrow = new TArrow(xend-dX, yend-dY, xend, yend, 0.05, "->-");
	arrow->Draw();
}