diff --git a/src/juobs_obs.jl b/src/juobs_obs.jl
index 4ce3fa9cb0caa054dd72c208c5ec9030233dd03b..634f6530f9c44a7e8797a182cc595ffee5a3bc4e 100644
--- a/src/juobs_obs.jl
+++ b/src/juobs_obs.jl
@@ -14,9 +14,9 @@ corr_pp = corr_obs.(data)
 m = meff(corr_pp[1], [50, 60], pl=false)
 ```
 """
-function meff(corr::Vector{uwreal}, plat::Vector{Int64}; pl::Bool=true, data::Bool=false)     
+function meff(corr::Vector{uwreal}, plat::Vector{Int64}; pl::Bool=true, data::Bool=false, mu::Union{Vector{Float64}, Nothing}=nothing)     
     dim = length(corr)                                                                                    
-    aux = log.(corr[2:dim-2] ./ corr[3:dim-1])     
+    aux = 0.5 .* log.((corr[2:dim-2] ./ corr[3:dim-1]).^2)     
     mass = plat_av(aux, plat)                                                                            
     uwerr(mass)                       
     if pl == true
@@ -31,6 +31,10 @@ function meff(corr::Vector{uwreal}, plat::Vector{Int64}; pl::Bool=true, data::Bo
         errorbar(x, y, dy, fmt="x", color="black")
         ylabel(L"$m_\mathrm{eff}$")
         xlabel(L"$x_0$")
+    
+        if !isnothing(mu)
+            title(string(L"$\mu_1 = $", mu[1], L" $\mu_2 = $", mu[2]))
+        end
         display(gcf())
     end                                                  
     if data == false                   
@@ -40,7 +44,7 @@ function meff(corr::Vector{uwreal}, plat::Vector{Int64}; pl::Bool=true, data::Bo
     end                    
 end   
 meff(corr::Corr, plat::Vector{Int64}; pl::Bool=true, data::Bool=false) = 
-    meff(corr.obs, plat, pl=pl, data=data)
+    meff(corr.obs, plat, pl=pl, data=data, mu=corr.mu)
 
 ## Decay constants                                                                                       
 @doc raw"""
@@ -83,6 +87,7 @@ function dec_const_pcvc(corr::Vector{uwreal}, plat::Vector{Int64}, m::uwreal, mu
         errorbar(1:length(R), value.(R), err.(R), fmt="x", color="black")
         ylabel(L"$R$")
         xlabel(L"$x_0$")
+        title(string(L"$\mu_1 = $", mu[1], L" $\mu_2 = $", mu[2]))
         display(gcf())          
     end 
     if data == false