Changes between Version 44 and Version 45 of Reweight

Timestamp:

Feb 22, 2016, 11:04:12 PM (8 years ago)

Author:

Olivier Mattelaer

Comment:

--

Reweight

@@ -43 +43 @@
    $$\mathcal{W}_V^{new} = \frac{V^{new}}{V^{old}} * \mathcal{W}_V^{old} $$
    $$\mathcal{W}_R^{new} = \frac{R^{new}}{R^{old}} * \mathcal{W}_R^{old} $$
- with the final weight computed by recombining these weights according to the prescription given before. This method of reweighting is called "NLO_basic".
-
-
- In MadGraph5_aMC@NLO, we have implemented a second NLO accurate method of re-weighting. This method dubbed "NLO_VT" is expected to have a smaller statistical uncertainty than the basic one. One potential problem of the "NLO_basic" method is related to the procedure adopted in the computation of the virtual contribution (see sect.2.4.3 http://arxiv.org/pdf/1405.0301.pdf). This speed optimisation method can easily statistical error associated to a sub-sample of events. To estimate such effect we propose this second reweighting  method --which should be less sensitive to such effects--. The difference between those two methods should be seen as a systematics. 
+ with the final weight computed by recombining these weights according to the prescription given before. This method of reweighting is called "'''NLO_basic'''".
+
+
+ In MadGraph5_aMC@NLO, we have implemented a second NLO accurate method of re-weighting. This method dubbed "'''NLO_VT'''" is expected to have a smaller statistical uncertainty than the basic one. One potential problem of the "NLO_basic" method is related to the procedure adopted in the computation of the virtual contribution (see sect.2.4.3 http://arxiv.org/pdf/1405.0301.pdf). This speed optimisation method can easily statistical error associated to a sub-sample of events. To estimate such effect we propose this second reweighting  method --which should be less sensitive to such effects--. The difference between those two methods should be seen as a systematics. 
 For this re-weighting, $\mathcal{W}_B$ is split in two pieces :$\mathcal{W}_{BC}$, $\mathcal{W}_{BB}$. $\mathcal{W}_{BC}$ is the part, proportional to the Born, related to the one of the counterterms, while $\mathcal{W}_{BB}$ includes all of the other contributions (the Born itself and the approximate virtual).
  The reweighting is then carried out as follows: