This article reports world averages of measurements of
b
-hadron,
c
-hadron, and
τ
-lepton properties obtained by the Heavy Flavor Averaging Group using results available through summer 2016. For the ...averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters,
C
P
violation parameters, parameters of semileptonic decays, and Cabbibo–Kobayashi–Maskawa matrix elements.
Punzi-loss Abudinén, F.; Bertemes, M.; Bilokin, S. ...
The European physical journal. C, Particles and fields,
2022/2, Letnik:
82, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We present the novel implementation of a non-differentiable metric approximation and a corresponding loss-scheduling aimed at the search for new particles of unknown mass in high energy physics ...experiments. We call the loss-scheduling, based on the minimisation of a figure-of-merit related function typical of particle physics, a Punzi-loss function, and the neural network that utilises this loss function a Punzi-net. We show that the Punzi-net outperforms standard multivariate analysis techniques and generalises well to mass hypotheses for which it was not trained. This is achieved by training a single classifier that provides a coherent and optimal classification of all signal hypotheses over the whole search space. Our result constitutes a complementary approach to fully differentiable analyses in particle physics. We implemented this work using PyTorch and provide users full access to a public repository containing all the codes and a training example.
Punzi-loss Abudinén, F; Bertemes, M; Bilokin, S ...
European physical journal. C, Particles and fields,
02/2022, Letnik:
82, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We present the novel implementation of a non-differentiable metric approximation and a corresponding loss-scheduling aimed at the search for new particles of unknown mass in high energy physics ...experiments. We call the loss-scheduling, based on the minimisation of a figure-of-merit related function typical of particle physics, a Punzi-loss function, and the neural network that utilises this loss function a Punzi-net. We show that the Punzi-net outperforms standard multivariate analysis techniques and generalises well to mass hypotheses for which it was not trained. This is achieved by training a single classifier that provides a coherent and optimal classification of all signal hypotheses over the whole search space. Our result constitutes a complementary approach to fully differentiable analyses in particle physics. We implemented this work using PyTorch and provide users full access to a public repository containing all the codes and a training example.
Abstract This article reports world averages of measurements of b-hadron, c-hadron, and $$\tau $$ τ -lepton properties obtained by the Heavy Flavor Averaging Group using results available through ...summer 2016. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, $$C\!P$$ C P violation parameters, parameters of semileptonic decays, and Cabbibo–Kobayashi–Maskawa matrix elements.
This paper reports world averages of measurements of
b
-hadron,
c
-hadron, and
τ
-lepton properties obtained by the Heavy Flavour Averaging Group using results available through September 2018. In ...rare cases, significant results obtained several months later are also used. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters,
C
P
violation parameters, parameters of semileptonic decays, and Cabibbo–Kobayashi–Maskawa matrix elements.
Global decay chain vertex fitting at Belle II Krohn, J.-F.; Tenchini, F.; Urquijo, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2020, Letnik:
976, Številka:
C
Journal Article
Recenzirano
Odprti dostop
In this paper we report the implementation of a global vertex fitting algorithm within the Belle II analysis software environment, which was originally developed for BaBar (Hulsbergen, 2005). We ...explore the impact of global vertex fitting algorithms for flavour physics analyses with the Belle II detector at the SuperKEKB e+e− collider, such as in the reconstruction of final states with neutral particles, and in fits with geometrical constraints from SuperKEKB’s nano-beam interaction region. The algorithm is compared to the standard vertex fitting algorithm employed by the Belle experiment. We have developed the fitting framework to utilise the EIGEN library for linear algebra operations, reducing the computation time for vertex fitting operations by an order of magnitude over previous methods. This has a significant impact on physics analysis computing efficiency, where vertex fitting over large combinations of final state particles is one of the most CPU intensive operations at Belle II.
The Full Event Interpretation Keck, T.; Abudinén, F.; Bernlochner, Florian U. ...
Computing and software for big science,
12/2019, Letnik:
3, Številka:
1
Journal Article
Odprti dostop
The full event interpretation is presented: a new exclusive tagging algorithm used by the high-energy physics experiment Belle II. The experimental setup of Belle II allows the precise measurement of ...otherwise inaccessible
B
meson decay modes. The Full Event Interpretation algorithm enables many of these measurements. The algorithm relies on machine learning to automatically identify plausible
B
meson decay chains based on the data recorded by the detector. Compared to similar algorithms employed by previous experiments, the Full Event Interpretation provides a greater efficiency, yielding a larger effective sample size usable in the measurement.
We present a comprehensive study of B^{0}→ωω decays using 772×10^{6} BBover ¯ pairs collected with the Belle detector at the KEKB e^{+}e^{-} collider. This process is a suppressed charmless decay ...into two vector mesons and can exhibit interesting polarization and CP violation. The decay is observed for the first time with a significance of 7.9 standard deviations. We measure a branching fraction B=(1.53±0.29±0.17)×10^{-6}, a fraction of longitudinal polarization f_{L}=0.87±0.13±0.13, and a time-integrated CP asymmetry A_{CP}=-0.44±0.43±0.11, where the first uncertainties listed are statistical and the second are systematic. This is the first observation of B^{0}→ωω and the first measurements of f_{L} and A_{CP} for this decay.We present a comprehensive study of B^{0}→ωω decays using 772×10^{6} BBover ¯ pairs collected with the Belle detector at the KEKB e^{+}e^{-} collider. This process is a suppressed charmless decay into two vector mesons and can exhibit interesting polarization and CP violation. The decay is observed for the first time with a significance of 7.9 standard deviations. We measure a branching fraction B=(1.53±0.29±0.17)×10^{-6}, a fraction of longitudinal polarization f_{L}=0.87±0.13±0.13, and a time-integrated CP asymmetry A_{CP}=-0.44±0.43±0.11, where the first uncertainties listed are statistical and the second are systematic. This is the first observation of B^{0}→ωω and the first measurements of f_{L} and A_{CP} for this decay.
We report the results of the first search for B^{-} decays to the Ξover ¯_{c}^{0}Λover ¯_{c}^{-} final state using 711 fb^{-1} of data collected at the ϒ(4S) resonance with the Belle detector at the ...KEKB asymmetric-energy e^{+}e^{-} collider. The results are interpreted in terms of both direct baryon-number-violating B^{-} decay and Ξ_{c}^{0}-Ξover ¯_{c}^{0} oscillations which follow the standard model decay B^{-}→Ξ_{c}^{0}Λover ¯_{c}^{-}. We observe no evidence for baryon number violation and set the 95% confidence-level upper limits on the ratio of baryon-number-violating and standard model branching fractions B(B^{-}→Ξover ¯_{c}^{0}Λover ¯_{c}^{-})/B(B^{-}→Ξ_{c}^{0}Λover ¯_{c}^{-}) to be <2.7% and on the effective angular frequency of mixing ω in Ξ_{c}^{0}-Ξover ¯_{c}^{0} oscillations to be <0.76 ps^{-1} (equivalent to τ_{mix}>1.3 ps).We report the results of the first search for B^{-} decays to the Ξover ¯_{c}^{0}Λover ¯_{c}^{-} final state using 711 fb^{-1} of data collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. The results are interpreted in terms of both direct baryon-number-violating B^{-} decay and Ξ_{c}^{0}-Ξover ¯_{c}^{0} oscillations which follow the standard model decay B^{-}→Ξ_{c}^{0}Λover ¯_{c}^{-}. We observe no evidence for baryon number violation and set the 95% confidence-level upper limits on the ratio of baryon-number-violating and standard model branching fractions B(B^{-}→Ξover ¯_{c}^{0}Λover ¯_{c}^{-})/B(B^{-}→Ξ_{c}^{0}Λover ¯_{c}^{-}) to be <2.7% and on the effective angular frequency of mixing ω in Ξ_{c}^{0}-Ξover ¯_{c}^{0} oscillations to be <0.76 ps^{-1} (equivalent to τ_{mix}>1.3 ps).
We report the first measurement of the Michel parameter ξ′ in the τ−→μ−¯νμντ decay with a new method proposed just recently. The measurement is based on the reconstruction of the τ−→μ−¯νμντ events ...with subsequent muon decay in flight in the Belle central drift chamber. The analyzed data sample of 988 fb−1 collected by the Belle detector corresponds to approximately 912×106 τ+τ− pairs. We measure ξ′=0.22±0.94(stat)±0.42(syst), which is in agreement with the standard model prediction of ξ′=1. Statistical uncertainty dominates in this study, being a limiting factor, while systematic uncertainty is well under control. Our analysis proved the practicability of this promising method and its prospects for further precise measurement in future experiments.
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