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Good Morning Holly,



I've started looking into this. I had already noticed that there are some issues with the information in the vertex collections that I was trying to understand. I'm beginning to doubt that we are applying the correct transformation to the input stdhep files.



Norman

________________________________
From: Holly Vance <[log in to unmask]>
Sent: Friday, March 31, 2017 3:11 PM
To: Graf, Norman A.; hps-software
Subject: Vertex re-fit momentum and mass

Hi Norman,

There seems to be some problem in obtaining the vertex re-fit momentum in our code (maybe I am not understanding). You wrote an old example driver, that I've copied below for reference, and we have implemented the following into our code:

uncV0.getStartVertex().getParameters().get("p1X")
uncV0.getMass()


It seems that this mass is not good for the L2L2 dataset, and I think Matt is seeing something funny in the L0 data using this. However, the result is better if we don't use the vertex re-fit momentum and just use the XYZ momentum components of the track prior to the re-fit.

Can you take a look into this? Matt S is also working on this and might also comment. He thinks it's possible that the beam rotation is not in this output and is maybe also contributing the poor mass reconstruction.

-Holly




~~~~~~~~~
Example code:

package org.hps.analysis.examples;

import java.util.List;
import java.util.Map;
import org.lcsim.event.EventHeader;
import org.lcsim.event.Vertex;
import org.lcsim.util.Driver;

/**
 *
 * @author Norman A. Graf
 */
public class VertexAnalysis extends Driver {

    String vertexCollectionName = "TargetConstrainedV0Vertices";

    protected void process(EventHeader event) {
        List<Vertex> vertices = event.get(Vertex.class, vertexCollectionName);
        for (Vertex v : vertices) {
            Map<String, Double> vals = v.getParameters();
            System.out.println(vals);
        }
    }
}

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