Recent Improvements of the ROOT Fitting and Minimization Classes

Moneta, L.; Maline, D González; Antcheva, I

doi:10.22323/1.070.0075

Cited by 5 publications

(5 citation statements)

References 7 publications

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“…as the distribution is sometimes given, the logic changes and the right peak is always more likely. We note that the ROOT implementation [70,71] of the Breit-Wigner function has unit numerator.…”

Section: Impact Of the Transfer Functionsmentioning

confidence: 99%

On the ATLAS top mass measurements and the potential for stealth stop contamination

Cohen¹,

Majewski²,

Ostdiek³

et al. 2020

J. High Energ. Phys.

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The discovery of the stop-the Supersymmetric partner of the top quarkis a key goal of the physics program enabled by the Large Hadron Collider. Although much of the accessible parameter space has already been probed, all current searches assume the top mass is known. This is relevant for the "stealth stop" regime, which is characterized by decay kinematics that force the final state top quark off its mass shell; such decays would contaminate the top mass measurements. We investigate the resulting bias imparted to the template method based ATLAS approach. A careful recasting of these results shows that effect can be as large as 2.0 GeV, comparable to the current quoted uncertainty on the top mass. Thus, a robust exploration of the stealth stop splinter requires the simultaneous consideration of the impact on the top mass. Additionally, we explore the robustness of the template technique, and point out a simple strategy for improving the methodology implemented for the semi-leptonic channel.

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Section: Impact Of the Transfer Functionsmentioning

confidence: 99%

On the ATLAS top mass measurements and the potential for stealth stop contamination

Cohen¹,

Majewski²,

Ostdiek³

et al. 2020

J. High Energ. Phys.

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“…(5.1), using Φ I (0 • ) and n as free parameters. The MINUIT package [31] of the ROOT program [32] was used to perform the fit and the estimation of the parameter errors. The χ 2 /ndf of the three fits, where ndf = 9 is the number of degrees of freedom, are below 1 when the quadratic sum of the statistical and systematic uncertainties is attributed to the integral flux errors of figure 5.…”

Section: Resultsmentioning

confidence: 99%

Angular distribution of low momentum atmospheric muons at ground level

Briki

Mazouz

Ghedira

2023

J. Cosmol. Astropart. Phys.

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We report measurements of the angular distributions of low momentum atmospheric muons at 38 m above sea level for zenith angles θ between -60 and 60 degrees in the south-north direction. The muon detection was performed with two NaI(Tl) scintillation detectors mounted in coincidence. An adjustable lead thickness placed between the detectors allowed to select muons with a minimal momentum ranging from 0.3 to 0.9 GeV/c. The integrated and the differential muon flux were determined by analyzing the deposited energy spectra in the scintillators backed up by a Geant4 simulation of the experimental setup. The results are consistent with the cos n (θ) distribution in good agreement with the literature. These data contribute to fill the gap in the geomagnetic cutoff rigidity interval 8 GV < Pc < 14 GV where no similar measurements were performed before. We found that n = 1.88 - 0.12 Pμ c in this domain of muon momenta cutoff Pμ c < 1 GeV/c. The present measurements are useful for many muon studies requiring an accurate integrated flux.

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“…A software package, called BLUEFIN 1 , was specifically prepared to study all these issues. Within this package, numerical minimizations are performed using the MINUIT [12] libraries through their integration in ROOT [13], imposing the constraints that scale factors remain between 0 and 1. All scale factors are varied in the minimization, except those which are known to have no effect on information because the information derivatives with respect to them (which are essentially those presented in Sec.…”

Section: Minimizing Information By Numerical Methodsmentioning

confidence: 99%

Information and treatment of unknown correlations in the combination of measurements using the BLUE method

Valassi

Chierici

2014

Eur. Phys. J. C

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We discuss the effect of large positive correlations in the combinations of several measurements of a single physical quantity using the Best Linear Unbiased Estimate (BLUE) method. We suggest a new approach for comparing the relative weights of the different measurements in their contributions to the combined knowledge about the unknown parameter, using the well-established concept of Fisher information. We argue, in particular, that one contribution to information comes from the collective interplay of the measurements through their correlations and that this contribution cannot be attributed to any of the individual measurements alone. We show that negative coefficients in the BLUE weighted average invariably indicate the presence of a regime of high correlations, where the effect of further increasing some of these correlations is that of reducing the error on the combined estimate. In these regimes, we stress that assuming fully correlated systematic uncertainties is not a truly conservative choice, and that the correlations provided as input to BLUE combinations need to be assessed with extreme care instead. In situations where the precise evaluation of these correlations is impractical, or even impossible, we provide tools to help experimental physicists perform more conservative combinations.

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Recent Improvements of the ROOT Fitting and Minimization Classes

Cited by 5 publications

References 7 publications

On the ATLAS top mass measurements and the potential for stealth stop contamination

On the ATLAS top mass measurements and the potential for stealth stop contamination

Angular distribution of low momentum atmospheric muons at ground level

Information and treatment of unknown correlations in the combination of measurements using the BLUE method

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