Project

General

Profile

Kaon LT Meetings » mtg_24mar14.txt

Garth Huber, 03/14/2024 06:49 PM

 
1
                 Mar 14/24 PionLT/KaonLT Analysis Meeting Notes
2
                 ----------------------------------------------
3
                                (Notes by GH)
4

    
5
                     Today: KaonLT will be discussed first
6

    
7
Please remember to post your slides at:
8
https://redmine.jlab.org/projects/kltexp/wiki/Kaon_LT_Meetings
9

    
10
Present
11
-------
12
Regina - Garth Huber, Nacer Hamdi, Ali Usman, Muhammad Junaid, Nathan Heinrich,
13
   Vijay Kumar, Alicia Postuma
14
CUA - Richard Trotta
15
York - Stephen Kay
16
CSULA - Konrad Aniol
17
JLab - Dave Gaskell
18

    
19
Ali
20
---
21
MM shape study for DeltaPi BSA
22
- reran MC's with new resolution parameter
23
- starting on settings with lower P_HMS, where delta correction is not needed
24
- shows Q2=3.0, W=3.14, high stats setting, positive helicity
25
  - initial fit of MCs to data
26
  - new 10 MeV/bin instead of previous 4 MeV/bin (lower statistical errors/bin)
27
  - with new MM binning, it is now more clear that strength of DeltaPi peak is
28
    underestimated for some phi-bins
29
  - since SIDIS and rho bkds are so similar, using a fixed ratio of 90%
30
    SIDIS/10% rho for now
31
  - cyan=sum of bkds, pi+n tail+SIDIS+rho
32
  - optimistic that 2 t-bins can eventually be used for this setting (data
33
    shown is over full t-range)
34
- GH: since they are so similar, why don't you try fitting just one of rho or
35
  SIDIS to see which one is better, and just use that one?
36
  - DG: this would be an unphysical choice, but it probably makes no difference
37
    to your analysis
38
- Nacer: why are you fitting each phi bin separately?
39
  - we have confidence that SIMC can properly describe the shapes for the
40
    different processes, but not their amplitudes, so we need to fit each phi
41
    bin separately
42

    
43
Alicia
44
------
45
MM cut study after resolution correction implemented in SIMC
46
- Dave suggested calculating Data/SIMC ratio for different MM cut values
47
  - UofR group meeting also suggested to compare w/ w/o HGC cut
48
    - HGC gets rid of KLambda leakthrough but not the shape of the region
49
      between pi+n and KLambda
50
  - ratios do not in general have a plateau vs MM cut
51
    - Q2=3, W=3.14 data shown
52
      - t-bins 1,2 show a decrease in ratio vs MM
53
      - t-bin 3 shows a plateau
54
      - t-bins 4-6 show an increase vs MM
55
    - behavior is similar for Q2=4.5, 5.5
56
- since the ratio is not flat, will instead try placing MM cut in region where
57
  expt yield is flat
58
  - Q2=5.5, flat region is MM=0.99-1.03, so will try MM cuts 1.01+/-0.02
59
  - Q2=4.4, Q2=3.0 W=3.14, flat region looks similar, so same MM cut
60
  - GH: can't think of anything better to try, given the situation
61

    
62
- Dave: have you looked at BSA vs MM cut?
63
  - a preliminary study was done last year, the final study will be done with
64
   these MM cuts
65

    
66
- Dave: if SIMC handles the radiative corrections properly, any cut below 2pi
67
  threshold should give the same answer
68
  - GH: not sure about this, the pion scattering in the collimator also
69
    populates this region, in Fpi-1,2 we had to use a cut well below 2pi
70
    threshold to avoid being too sensitive to this region
71

    
72
- Dave: there is no SHMS collimator routine in SIMC
73
  - GH: wasn't aware of no routine was included at all.
74
    *TASK for GH:* find the HMS collimator code used in Fpi-2 analysis, and get
75
    instructions on how to modify it for SHMS collimator geometry
76

    
77
- Nacer: can an RF cut be applied to help clean up this MM region?
78
  - no, only a small subset of 10.6 GeV data has the RF information available,
79
    unfortunately
80

    
81
HMS Delta-correction
82
- P_HMS=6.59, Q2=3, W=2.32 data
83
  - hcana uncorrected MMpi vs hsxpfp shows line with tilt on top half
84
  - using reconstructed MMpi script to determine correction
85
    - applying if hsxpfp>0: hsdelta+=3.0*hsxpfp
86
  - resulting MM distribution is narrowed
87
- P_HMS=5.292, Q2=2.1, W=2.95 data
88
  - hcana uncorrected MMpi vs hsxpfp shows line with tilt on bottom half
89
  - correction: if hsxpfp<0: hsdelta-=4.0*hsxpfp
90

    
91
- having difficulty implementing this correction in hcana
92
  - recompiling hcana on iFarm gives complaint about missing PODD variables
93
  - Stephen: please *send* the PODD error and he will look at his notes to see
94
    if he can fix
95
  - Nathan: thinks it might be better to implement correction in the kinematics
96
    file
97

    
98
CKY Regge model
99
- received LT' predictions from BG Yu for the BSA paper
100

    
101
Richard
102
-------
103
Subtracting pion leakthrough
104
- last week's results had HGC hole cut inverted, taking only events in the hole
105
- now the pi+ dist comes all the way across the MM acceptance
106
- Q2=2.1 setting, high epsilon
107
  - pi+ subtraction does not clean up region left of KLambda peak
108
  - planning to re-optimize PID cuts after graduation
109

    
110
Unsep and Separated Q2=3.0, W=2.32 xsect
111
- shows ratios vs phi,t at high, low epsilon
112
  - looking at what's responsible for Data/SIMC ratios being much larger at
113
    high eps than low eps
114
  - trying various initial values of model parameters
115
    sigL=g(W)*(p1+p2*logQ2)exp(p3+p4*logQ2)*(-t+0.2) 
116
    -- changed last part to just -t to get better t-dependence
117
    sigT=g(W)*p5/(1+p6*Q2)
118
  - Dave: maybe remove the Q2-dependence and only have a simple t-dependence
119

    
120
- Dave: the *real issue*, however, is that if you have sigL<0 from the
121
  beginning, there's a problem with the data itself, not the iteration
122
  - GH: exactly what MM region is integrated for these yields?
123
  - MM cut is applied after pi-subtraction
124
    - GH: if we can't clean up the region left of KLambda with cuts or pion
125
      subtraction, then we will have to consider fitting a polynomial and
126
      subtracting it
127
    - Dave: yes, we will need to sort this out
128

    
129
- Richard shows MM plots for same setting at high and low epsilon
130
  - RF cut can be used only at low epsilon, region left of KLambda is
131
    noticeably cleaner than high epsilon
132
  - GH notices that pion subtraction peak is much narrower than the pi+n MM
133
    leakthrough peak
134
  - Ali's pion sample was analyzed as if pions, not K, hence the peak is narrow
135
    - normalizing to the height of the pi+n peak will result in too little pion
136
      leakthrough being subtracted, as the integrals won't match
137
  - *Ali* will give Richard his cuts and RT will make a branch of his analysis
138
    for the pion subtraction
139

    
140
Vijay
141
-----
142
PionLT low Q2 lt-analysis
143
- found bug in script, error bars vs phi now more reasonable
144
- shows results after 1 iteration for Q2=0.38, all 3 epsilons
145
  - some discussion about phi-dependence of lowest t-bin
146
  - the low epsilon setting seems to have a different phi-dependence than mid
147
    and high eps, which is weird
148
    - Dave: this could indicate a residual offset issue, lowest t-bin is always
149
      more sensitive to the offsets
150
    - Vijay will investigate further
151
  - t-bins 2-7 have more consistent phi-dependence at low, mid, high epsilon
152
  - 8th t-bin has poor statistics, might have to be removed from analysis
153

    
154
- shows separated cross sections after 1st iteration, and model fits for
155
  iteration #2
156
  - t-bins 1,8 look like outliers for sigT,L after iteration #1
157
  - if only t-bins 2-7 included in fit, things are more consistent
158
  - will have to see what this looks like after more study
159

    
160
Nacer
161
-----
162
KaonLT low Q2 event selection
163
- won't show any plots, since the meeting is getting long
164
- tweaking some cuts, changing the RF windows
165
  - RF cut is very effective, needs fine tuning
166
  - GH: since the RF cut is so effective, you can probably get by with a
167
    combination of slightly looser PID cuts, to avoid cut-dependence to the
168
    result
169

    
170
Nathan
171
------
172
Setting up PionLT Luminosity analysis
173
- in contact with Dave Mack regarding BCM calibrations
174
  - DM did our first calibs from 2021 run, NH will follow up with him on run#'s
175
  - Dave: if you can generate ROOT trees for him to analyze, it would be even
176
    better
177

    
178
Weird hcana issue
179
- hcana suddenly did not know what replay variables were
180
  - spent a day debugging
181
  - restored things, but no idea what happened, as could not find any
182
    difference from how things were set up before
183

    
184
Going through Richard's python scripts and finding what's missing
185
- will plan on meeting RT in early April, after his defense
186

    
187
Junaid
188
------
189
Setting up PionLT Heep study
190
- had some issues with lt-sep package
191
- merged cut files for 2021,22
192
- added ngcer
193
- updated RF time offsets
194

    
195
PID cuts
196
- HMS cal-etot-track-norm>0.7
197
- HMS cer NPE>1.5
198
- CoinTime, extremely clean, practically no randoms
199
  - should be able to just place a cut around prompt peak, no random
200
    subtraction
201

    
202
Next Meeting
203
------------
204
- Thur Mar 21 @ 15:00 Eastern/13:00 Regina
205
  - PionLT will go first
206

    
207

    
208

    
(387-387/430)