[Hps-analysis] HPS Analysis Meeting June 26 @ 10am/1pm PDT/EDT

[Graham, Mathew Thomas]

Can you show a plot of just the invariant mass @ z ~0mm (pick a mass) in a  similar format Omar showed today?  I don’t see how these plots address what we are worried about (radiative tails in the invariant mass).



On Jun 26, 2018, at 4:06 PM, Solt, Matthew Reagan <mrsolt at slac.stanford.edu<mailto:mrsolt at slac.stanford.edu>> wrote:

Thanks for looking into this Sho.

I think bottom line, I just apply the truth x cut for the efficiency curves. I don't think this is cheating since we care about the truth for these.

Nan (a rotation student), did a quick and dirty study similar to this. He cut on the residual of both electron and positron momentum, decay z, and mass at 3 sigma for all these. Then he took the ratio between the efficiency curves (as a function of z) of those curves and the curves without those cuts. Results are below (ratio vs z for several A' masses). I originally was curious in the affect of the recoil electron in the reconstruction (those cuts should get rid of most of them), not the radiative tail as discussed this morning. The results are what I expected, a very large affect for low mass (which always has a large tail in mass), and a slightly larger affect neat the target where reconstructing with the recoil electron is more likely. In our mass and z region of interest (~>30 mm and mass > 35 MeV), it seems like a 5-10% effect.

<pastedImage.png> at
Same plot but with error bars

<pastedImage.png>

More details are here if you want to see some of the tails he cut out: https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_nanw0321_HPS_tree_master_Plots_vertex-5Fcut&d=DwIGaQ&c=lz9TcOasaINaaC3U7FbMev2lsutwpI4--09aP8Lu18s&r=J4PP6Zl8IyGHpsqWaKegORCYw8hoCHePTw5O95a5lqQ&m=jUMosVsECpbuEahfoTOoLu_TzxRGB0wTRCrR6FYFUpA&s=ScIGqVD757qZ43t-TvjluH_aGZ2Vku-LXNpVDU9APUs&e= 

Matt Solt
________________________________
From: Hps-analysis <hps-analysis-bounces at jlab.org<mailto:hps-analysis-bounces at jlab.org>> on behalf of Sho Uemura <meeg at slac.stanford.edu<mailto:meeg at slac.stanford.edu>>
Sent: Tuesday, June 26, 2018 1:44:52 PM
To: Graham, Mathew Thomas
Cc: hps-analysis at jlab.org<mailto:hps-analysis at jlab.org>
Subject: Re: [Hps-analysis] HPS Analysis Meeting June 26 @ 10am/1pm PDT/EDT

I read the note, it looks good so far. I've made a couple of typo fixes
and I'll put more substantive comments in a text file (in the Dropbox,
comments_sho/comments.txt), but the only things I have there right now are
things I screwed up in my thesis.

I looked at the low-mass tail (pyroot macro and plots attached). See the
comments in the macro for detail, but summary: I'd misremembered what the
cut is that cleans it up: it's not the radiative cut on the recon vertex,
it's a x>0.8 cut on the truth A'. So, that's obviously cheating (in my
thesis I say I'm doing it, but completely sweep it under the rug). But the
tail I saw (might not be the same tail you see) is definitely recoil e-
misidentification in low-X A' events.

On Tue, 26 Jun 2018, Graham, Mathew Thomas wrote:

>
> Hi All,
>
> We?ll meet tomorrow for an update on things in the run-up to ICHEP.  We?ve got both the 2015 bump-hunt and vertexing analysis aiming for it and this Wednesday is the nominal deadline for presenting the results to the collaboration.
>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__confluence.slac.stanford.edu_display_hpsg_June-2B26-252C-2B2018-2BDAWG-2BMeeting&d=DwIGaQ&c=lz9TcOasaINaaC3U7FbMev2lsutwpI4--09aP8Lu18s&r=J4PP6Zl8IyGHpsqWaKegORCYw8hoCHePTw5O95a5lqQ&m=k4vmYUNmn_n-5PP-EHertr6XxvPSqcKO5XvWw2_iXGE&s=tfApseM4CjHLmQsSyzN2_qiQXCcyyhPiyBz4KuhbuJs&e=<https://urldefense.proofpoint.com/v2/url?u=https-3A__confluence.slac.stanford.edu_display_hpsg_June-2B26-2C-2B2018-2BDAWG-2BMeeting&d=DwIGaQ&c=lz9TcOasaINaaC3U7FbMev2lsutwpI4--09aP8Lu18s&r=J4PP6Zl8IyGHpsqWaKegORCYw8hoCHePTw5O95a5lqQ&m=k4vmYUNmn_n-5PP-EHertr6XxvPSqcKO5XvWw2_iXGE&s=0pcsXe14RWQBSJw6vopXDE59LApRfHspxGQ9MmL_W5o&e=>
>
> Thanks, Matt & Nathan
>
>
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