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.
We present the first model-independent measurement of the CKM unitarity triangle angle ϕ3 using B±→ D(KS0\ {K}_{\mathrm{S}}^0 \π+π−π0) K± decays, where D indicates either a D0 or D¯\ \overline{D} \0 ...meson. Measurements of the strong-phase difference of the D →KS0\ {K}_{\mathrm{S}}^0 \π+π−π0 amplitude obtained from CLEO-c data are used as input. This analysis is based on the full Belle data set of 772 × 106BB¯\ \overline{B} \ events collected at the Υ(4S) resonance. We obtain ϕ3 = (5.7−8.8+10.2\ {5.7}_{-8.8}^{+10.2} \±3.5±5.7)° and the suppressed amplitude ratio rB = 0.323±0.147±0.023±0.051. Here the first uncertainty is statistical, the second is the experimental systematic, and the third is due to the precision of the strong-phase parameters measured from CLEO-c data. The 95% confidence interval on ϕ3 is (−29.7, 109.5)°, which is consistent with the current world average.
Charged lepton flavor violation is forbidden in the Standard Model but possible in several new physics scenarios. In many of these models, the radiative decays τ± → ℓ±γ (ℓ = e, μ) are predicted to ...have a sizeable probability, making them particularly interesting channels to search at various experiments. An updated search via τ± → ℓ±γ using full data of the Belle experiment, corresponding to an integrated luminosity of 988 fb–1, is reported for charged lepton flavor violation. No significant excess over background predictions from the Standard Model is observed, and the upper limits on the branching fractions, B(τ± → μ±γ) ≤ 4.2 × 10–8 and B(τ± → e±γ) ≤ 5.6 × 10–8, are set at 90% confidence level.
A
bstract
We present the first model-independent measurement of the CKM unitarity triangle angle
ϕ
3
using
B
±
→ D
(
K
S
0
π
+
π
−
π
0
)
K
±
decays, where
D
indicates either a
D
0
or
D
¯
0
meson. ...Measurements of the strong-phase difference of the
D →
K
S
0
π
+
π
−
π
0
amplitude obtained from CLEO-c data are used as input. This analysis is based on the full Belle data set of 772
×
10
6
B
B
¯
events collected at the Υ(4
S
) resonance. We obtain
ϕ
3
= (
5.7
−
8.8
+
10.2
±
3
.
5
±
5
.
7)
°
and the suppressed amplitude ratio
r
B
= 0
.
323
±
0
.
147
±
0
.
023
±
0
.
051. Here the first uncertainty is statistical, the second is the experimental systematic, and the third is due to the precision of the strong-phase parameters measured from CLEO-c data. The 95% confidence interval on
ϕ
3
is (
−
29
.
7
,
109
.
5)
°
, which is consistent with the current world average.
We report evidence for the charged charmed-strange baryon Formula omitted with a signal significance of 3.9 Formula omitted with systematic errors included. The charged Formula omitted is found in ...its decay to Formula omitted in the substructure of Formula omitted decays. The measured mass and width are Formula omitted MeV/ Formula omitted and Formula omitted MeV, respectively, and the product branching fraction is Formula omitted. We also measure Formula omitted with greater precision than previous experiments, and present the results of a search for the charmonium-like state Y(4660) and its spin partner, Formula omitted, in the Formula omitted invariant mass spectrum. No clear signals of the Y(4660) or Formula omitted are observed and the 90% credibility level (C.L.) upper limits on their production rates are determined. These measurements are obtained from a sample of Formula omitted pairs collected at the Formula omitted resonance by the Belle detector at the KEKB asymmetric energy electron-positron collider.
We report evidence for the charged charmed-strange baryon \(\Xi _{c}(2930)^+\) with a signal significance of 3.9 \(\sigma \) with systematic errors included. The charged \(\Xi _{c}(2930)^+\) is found ...in its decay to \(K_{S}^{0} \Lambda _{c}^+\) in the substructure of \(\bar{B}^{0} \rightarrow K^{0}_{S} \Lambda _{c}^{+} \bar{\Lambda }_{c}^{-}\) decays. The measured mass and width are \(2942.3 \pm 4.4 ({\mathrm{stat.}}) \pm {1.5}({\mathrm{syst.}})\) MeV/ \(c^{2}\) and \(14.8 \pm 8.8({\mathrm{stat.}}) \pm {2.5}({\mathrm{syst.}})\) MeV, respectively, and the product branching fraction is \(\mathcal{B}(\bar{B}^{0} \rightarrow \Xi _c(2930)^{+} \bar{\Lambda }_{c}^{-}) \mathcal{B}(\Xi _c(2930)^{+}\rightarrow \bar{K}^{0} \Lambda _{c}^{+})=2.37 \pm 0.51 ({\mathrm{stat.}})\pm 0.31({\mathrm{syst.}})\times 10^{-4}\) . We also measure \(\mathcal{B}(\bar{B}^{0} \rightarrow \bar{K}^{0} \Lambda _{c}^{+} \bar{\Lambda }_{c}^{-}) = 3.99 \pm 0.76({\mathrm{stat.}}) \pm 0.51({\mathrm{syst.}}) \times 10^{-4}\) with greater precision than previous experiments, and present the results of a search for the charmonium-like state Y(4660) and its spin partner, \(Y_{\eta }\) , in the \(\Lambda _{c}^{+}\bar{\Lambda }_{c}^{-}\) invariant mass spectrum. No clear signals of the Y(4660) or \(Y_{\eta }\) are observed and the 90% credibility level (C.L.) upper limits on their production rates are determined. These measurements are obtained from a sample of \((772\pm 11)\times 10^{6} B\bar{B}\) pairs collected at the \(\Upsilon (4S)\) resonance by the Belle detector at the KEKB asymmetric energy electron-positron collider.
We study bottomonium production in association with an Formula omitted meson in Formula omitted annihilations near the Formula omitted, at a centre-of-mass energy of Formula omitted GeV. The results ...are based on the 121.4 fb Formula omitted data sample collected by the Belle experiment at the asymmetric-energy KEKB collider. Only the Formula omitted meson is reconstructed and the missing-mass spectrum of Formula omitted candidates is investigated. We observe the Formula omitted process and find evidence for the Formula omitted process, while no significant signals of Formula omitted, Formula omitted, nor Formula omitted are found. Cross sections for the studied processes are reported.
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