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Monitoring of physics performance of ILC Software based on Higgs Recoil Mass
This content has been downloaded from IOPscience. Please scroll down to see the full text. 2016 J. Phys.: Conf. Ser. 675 022024 (http://iopscience.iop.org/1742-6596/675/2/022024) View the table of contents for this issue, or go to the journal homepage for more
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International Conference on Particle Physics and Astrophysics (ICPPA-2015) IOP Publishing Journal of Physics: Conference Series 675 (2016) 022024 doi:10.1088/1742-6596/675/2/022024
Monitoring of physics performance of ILC Software based on Higgs Recoil Mass E Volkova1,∗ and G Voutsinas2 1
National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe highway 31, Moscow, 115409, Russia 2 DESY, 22607, Hamburg, Germany E-mail: ∗
[email protected],
[email protected] Abstract. We discuss a part of ILC software development, that allow us to make automated testing of ILC results. The testing code consists of automated everyday Higgs recoil mass analysis and compares Higgs recoil mass with one of the previous day result. This code uses the result of generation, Mokka simulation and Marlin reconstruction of ILC events.
1. Introduction The ILD detector is one of two detectors of the International Linear Collider [1], that will collide electrons and positrons at energies of initially 500 GeV, upgradeable to 1 TeV. The ILC software will consists of ≈60 packages, developed by people in different institutes. A key task in software development is the automated testing on different levels of the process: at compile and build time, at runtime and on the results level. The first testing tasks are more technical, while the latter one relies on physics and statistics understanding. The physics performance will be monitored via the simulation study of the Higgs boson production for processes in which the Higgs is produced together with a well measurable dimuon system using the current proposal of the ILD detector. This part of ILC software can be included in the highly builds, comparing everyday the obtained value of the Higgs recoil mass with the one of the previous day. The higgs recoil mass reconstruction was conducted based on Marlin and Mokka modeling of ILD. More information about ILC is in [2]. 2. Higgs recoil mass The relevant process for the present study is the recoil reaction e+ e− → HZ → Hf f¯ (where f=leptons and quarks), also called Higgs-strahlung. Higgs recoil mass was reconstructed in the HZ → µ+ µ− X process, because the track quality for muons is better and the Z-boson mass peak is more clear than for electrons [3]. All data analysed in this discussion have been produced by the GEANT4 generation (Ecms = 250 GeV), Mokka detector simulation and Marlin reconstruction. The generated Higgs boson mass is 120GeV /c2 . 500 f b−1 have been reconstructed with the use of Marlin software and two different reconstruction algorithms: DBD tracking and cellular automaton [4]. The final program will compare resalts of two parts with 5000 events every day. On development stage the programm reconstructed 2000 events and all interim results were showed for 2000 events. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by IOP Publishing Ltd 1
International Conference on Particle Physics and Astrophysics (ICPPA-2015) IOP Publishing Journal of Physics: Conference Series 675 (2016) 022024 doi:10.1088/1742-6596/675/2/022024
The first step of analysis was muon tracks selection and recovery of Z-boson from two muons, and the result is shown in figure 1.
a)
b)
Figure 1. Z-boson mass of two data parts: a) for first part of date; b) for secondpart of date. The Higgs recoil mass was calculated via the relative kinematic equation: √ 2 = s + MZ2 − 2EZ s, Mrecoil
(1)
Then the selection of one muon pair from each event was included for peak improvement. The idea of selection is to choose a muon pair that has the most close mass to the well known Z-boson mass [5]. The results for Higgs recoil mass with muons selection are shown in figure 2.
a)
b)
Figure 2. Higgs recoil mass with Z-boson select: a) for first part of date; b) for secondpart of date. The energy of the incoming beams is smeared with an energy spread of 0.3%, that is a one of the sources of tail. The another one is initial state radiation and beamstrahlung [6]. Fit function for resulting spectra consists of Gaussian for the Peak with Gaussian and Exponent functions for tail. Then for peak improvement the 70GeV/c2 < Mz < 110GeV/c2 cut and rebin was made, and the final result for two parts of 5000 events is represented in figure 3. This work was conducted in the framework of the DESY summer student program. 2
International Conference on Particle Physics and Astrophysics (ICPPA-2015) IOP Publishing Journal of Physics: Conference Series 675 (2016) 022024 doi:10.1088/1742-6596/675/2/022024
a)
b)
Figure 3. Final Higgs recoil mass: a) for first part of date Mreco =120.76±0.06; b) for secondpart of date 120.76±0.06. 3. Conclusion The testing code of ILC software was created and will be use in automated testing of ILC results via higgs recoil mass analyse of a lot of pairs independent parts, that will consist of 5000 events. The results of the program are shown on table 1, total error = 0.5GeV/c2 , the difference of values = 0.3GeV/c2 . Table 1. Higgs recoil mass for two different parts with 1000 events. Mean
Err
121.9 GeV/c2 122.17 GeV/c2
±0.5GeV/c2 ±0.19GeV/c2
The result for parts with 5000 events is shown on table 2, total error = 0.08GeV/c2 .
Table 2. Higgs recoil mass for two different parts with 5000 events. Mean
Err GeV/c2
±0.06GeV/c2 ±0.06GeV/c2
120.76 120.76 GeV/c2
The next step is to improve the fitting of the distribution. After that, the presented in the discussion part of ILC software can be included in the ILC software diagnostic tools. References [1] T Behnke et al. 2013 The International Linear Collider Technical Design ReportVolume 4: Detectors arXiv:1306.6329
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International Conference on Particle Physics and Astrophysics (ICPPA-2015) IOP Publishing Journal of Physics: Conference Series 675 (2016) 022024 doi:10.1088/1742-6596/675/2/022024
[2] K Fujii, et al. 2015 Physics Case for the International Linear Collider arXiv:hep-ex 1506.05992 [3] H Li, R Pschl and F. Richard 2009 HZ Recoil Mass and Cross Section Analysis at ILD LC-PHSM-2009-006 arXiv: 1202.1439 [4] F Gaede et al. 2014 Track reconstruction at the ILC: the ILD tracking software, in proceedings of 20th International Conference on Computing in High Energy and Nuclear Physics (CHEP2013) Journal of Physics 513 (2014) 022011 [5] J Beringer et al. 2012 (Particle Data Group), Review of Particle Physics Phys. Rev. D 86 010001 [6] T Barklow and P Chen 1992 Beamstrahlung Spectra in Next Generation Linear Colliders SLAC-PUB-5718 Rev. DAPNIA/SPP 92-02
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