A simple fix to the eps_K prediction (see flav-io#172) (flav-io#181)

As discussed in flav-io#172, the RG factors assume the quark masses used
are mq(mq), not mq(160 GeV).
- For the top, we add a new function to the running module get_mt_mt
  which calculates mt(mt) using the RunDec function mOS2mSI and the
  top pole mass.
- For the charm, the input parameter m_c is already mc(mc) from PDG,
  so use that.
- For the up, the input m_u is actually mu(2 GeV), but this is closer
  to mu(mu) than mu(160 GeV), and numerically the up mass is extremely
  unimportant anyway.

The epsK NP test has to be changed, since with the correct value of mc
the charm contribution to imag(M12) is larger (around 30% vs 10% with
the old value), and so the NP doesn't exactly double the SM value.

flavio/physics/mesonmixing/test_mesonmixing.py

@@ -190,4 +190,4 @@ def test_np(self):
         self.assertAlmostEqual(
             flavio.np_prediction('eps_K', w) / flavio.sm_prediction('eps_K'),
             2,
-            delta=0.15)  # difference due to NNLO evolution of SM contribution + charm contribution
+            delta=0.30)  # difference due to NNLO evolution of SM contribution + charm contribution

flavio/physics/mesonmixing/wilsoncoefficient.py

@@ -56,9 +56,9 @@ def cvll_d(par, meson, scale=160):
     charm-, and charm-top-contribution to the Wilson coefficient. This
     separation is necessary as they run differently.
     """
-    mt = flavio.physics.running.running.get_mt(par, scale)
-    mc = flavio.physics.running.running.get_mc(par, scale)
-    mu = flavio.physics.running.running.get_mu(par, scale)
+    mt = flavio.physics.running.running.get_mt_mt(par)
+    mc = par["m_c"]
+    mu = par["m_u"]
     mW = par['m_W']
     xt = mt**2/mW**2
     xc = mc**2/mW**2

flavio/physics/running/running.py

@@ -268,6 +268,21 @@ def _get_mt(mt_pole, alpha_s, scale):
     return crd.mOS2mMS(mt_pole, None, alpha_s, scale, 6, 3)
 
 
+def get_mt_mt(par):
+    r"""Get the scale invariant top quark mass mt(mt)."""
+    mt_pole = par['m_t']
+    return _get_mt_mt(mt_pole=mt_pole,
+                      alpha_s=get_alpha_s(par, mt_pole))
+
+
+# cached version
+@lru_cache(maxsize=config['settings']['cache size'])
+def _get_mt_mt(mt_pole, alpha_s):
+    r"""Get the scale invariant top quark mass mt(mt)."""
+    crd = rundec.CRunDec()
+    return crd.mOS2mSI(mt_pole, None, alpha_s, 6, 3)
+
+
 def make_wilson_rge_derivative(adm):
     if adm is None:
         return None