Print

---

Hey Norman,


The corrected mass that Sho uses as discussed this morning is:

corrM = uncM - 0.15e-3 * (elePX/eleP - posPX/posP) * uncVZ/uncM


 This seems to work, but it is hard to understand what is going on here. Also the variable ele/posuncPY (I think momentum in the detector x direction) is not symmetric about PY=0, which leads me to think that somewhere this rotation is not done correctly. This variable may also be used to compute the invariant mass. I'm not sure, but it would make sense.


Thanks.


Matt Solt

________________________________
From: [log in to unmask] <[log in to unmask]> on behalf of Graf, Norman A. <[log in to unmask]>
Sent: Monday, April 3, 2017 8:24 AM
To: Holly Vance; hps-software
Subject: Re: Vertex re-fit momentum and mass


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);
        }
    }
}

________________________________

Use REPLY-ALL to reply to list

To unsubscribe from the HPS-SOFTWARE list, click the following link:
https://listserv.slac.stanford.edu/cgi-bin/wa?SUBED1=HPS-SOFTWARE&A=1

########################################################################
Use REPLY-ALL to reply to list

To unsubscribe from the HPS-SOFTWARE list, click the following link:
https://listserv.slac.stanford.edu/cgi-bin/wa?SUBED1=HPS-SOFTWARE&A=1