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Ferber, T. (ORCID:0000000268490427)

Publications and source records attributed to Ferber, T. (ORCID:0000000268490427).

At least 37 records Β· Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Production cross sections of light and charmed mesons in 𝑒 + ⁒𝑒 βˆ’ annihilation near 10.58 GeV

We report measurements of production cross sections for 𝜌 + , 𝜌 0 , πœ”, 𝐾* + , 𝐾* 0 , πœ™, πœ‚, 𝐾$^0_𝑆$, 𝑓 0 ⁑(980), 𝐷 + , 𝐷 0 , 𝐷$^+_𝑠$, 𝐷* + , 𝐷* 0 , and 𝐷*$^+_𝑠$ in 𝑒 + ⁒𝑒 βˆ’ collisions at a center-of-mass energy near 10.58 GeV. The data were recorded by the Belle experiment, consisting of 571 fb βˆ’1 at 10.58 GeV and 74 fb βˆ’1 at 10.52 GeV. Production cross sections are extracted as a function of the fractional hadron momentum π‘₯ 𝑝 . The measurements are compared to pythia Monte Carlo generator predictions with various fragmentation settings, including those that have increased fragmentation into vector mesons over pseudoscalar mesons. The cross sections measured for light hadrons are consistent with no additional increase of vector over pseudoscalar mesons. The charmed-meson cross sections are compared to earlier measurementsβ€”when availableβ€”including older Belle results, which they supersede. They are in agreement before application of an improved initial-state radiation correction procedure that causes slight changes in their π‘₯ 𝑝 shapes.

fragmentation functions↗
DOE OSTI2025

Measurement of the time-integrated C P asymmetry in D 0 β†’ K S 0 K S 0 decays using Belle and Belle II data

We measure the time-integrated C P asymmetry in D 0 β†’ K S 0 K S 0 decays reconstructed in e + e βˆ’ β†’ c c Β― events collected by the Belle and Belle II experiments. The corresponding data samples have integrated luminosities of 980 and 428 fb βˆ’ 1 , respectively. The D 0 decays are required to originate from the D * + β†’ D 0 Ο€ + decay, which determines the charm flavor at production time. A control sample of D 0 β†’ K + K βˆ’ decays is used to correct for production and detection asymmetries. The result, ( βˆ’ 1.4 Β± 1.3 ( stat ) Β± 0.1 ( syst ) ) % , is consistent with previous determinations and with C P symmetry. Published by the American Physical Society 2025

Adachi, I. (ORCID:0000000322870173)β†—
DOE OSTI2025

Observation of time-dependent C P violation and measurement of the branching fraction of B 0 β†’ J / ψ Ο€ 0 decays

We present a measurement of the branching fraction and time-dependent charge-parity ( C P ) decay-rate asymmetries in B 0 β†’ J / ψ Ο€ 0 decays. The data sample was collected with the Belle II detector at the SuperKEKB asymmetric e + e βˆ’ collider in 2019–2022 and contains ( 387 Β± 6 ) Γ— 10 6 B B Β― meson pairs from Ο’ ( 4 S ) decays. We reconstruct 392 Β± 24 signal decays and fit the C P parameters from the distribution of the proper-decay-time difference of the two B mesons. We measure the branching fraction to be ( B 0 β†’ J / ψ Ο€ 0 ) = ( 2.00 Β± 0.12 Β± 0.09 ) Γ— 10 βˆ’ 5 and the direct and mixing-induced C P asymmetries to be C C P = 0.13 Β± 0.12 Β± 0.03 and S C P = βˆ’ 0.88 Β± 0.17 Β± 0.03 , respectively, where the first uncertainties are statistical and the second are systematic. We observe mixing-induced C P violation with a significance of 5.0 standard deviations for the first time in this mode. Published by the American Physical Society 2025

Adachi, I. (ORCID:0000000322870173)β†—
DOE OSTI2024

Measurement of the e + e βˆ’ β†’ Ο€ + Ο€ βˆ’ Ο€ 0 cross section in the energy range 0.62–3.50 GeV at Belle II

We report a measurement of the e + e βˆ’ β†’ Ο€ + Ο€ βˆ’ Ο€ 0 cross section in the energy range from 0.62 to 3.50 GeV using an initial-state radiation technique. We use an e + e βˆ’ data sample corresponding to 191 fb βˆ’ 1 of integrated luminosity, collected at a center-of-mass energy at or near the Ο’ ( 4 S ) resonance with the Belle II detector at the SuperKEKB collider. Signal yields are extracted by fitting the two-photon mass distribution in e + e βˆ’ β†’ Ο€ + Ο€ βˆ’ Ο€ 0 Ξ³ events, which involve a Ο€ 0 β†’ Ξ³ Ξ³ decay and an energetic photon radiated from the initial state. Signal efficiency corrections with an accuracy of 1.6% are obtained from several control data samples. The uncertainty on the cross section at the Ο‰ and Ο• resonances is dominated by the systematic uncertainty of 2.2%. The resulting cross sections in the 0.62–1.80 GeV energy range yield a ΞΌ 3 Ο€ = [ 48.91 Β± 0.23 ( stat ) Β± 1.07 ( syst ) ] Γ— 10 βˆ’ 10 for the leading-order hadronic vacuum polarization contribution to the muon anomalous magnetic moment. This result differs by 2.5 standard deviations from the most precise current determination. Published by the American Physical Society 2024

Adachi, I. (ORCID:0000000322870173)β†—
DOE OSTI2024

Search for the baryon number and lepton number violating decays Ο„ βˆ’ β†’ Ξ› Ο€ βˆ’ and Ο„ βˆ’ β†’ Ξ› Β― Ο€ βˆ’ at Belle II

We present a search for the baryon number B and lepton number L violating decays Ο„ βˆ’ β†’ Ξ› Ο€ βˆ’ and Ο„ βˆ’ β†’ Ξ› Β― Ο€ βˆ’ produced from the e + e βˆ’ β†’ Ο„ + Ο„ βˆ’ process, using a 364 fb βˆ’ 1 data sample collected by the Belle II experiment at the SuperKEKB collider. No evidence of signal is found in either decay mode, which have | Ξ” ( B βˆ’ L ) | equal to 2 and 0, respectively. Upper limits at 90% credibility level on the branching fractions of Ο„ βˆ’ β†’ Ξ› Ο€ βˆ’ and Ο„ βˆ’ β†’ Ξ› Β― Ο€ βˆ’ are determined to be 4.7 Γ— 10 βˆ’ 8 and 4.3 Γ— 10 βˆ’ 8 , respectively. Published by the American Physical Society 2024

Adachi, I. (ORCID:0000000322870173)β†—
DOE OSTI2024

Test of lepton flavor universality with a measurement of R ( D * ) using hadronic B tagging at the Belle II experiment

The ratio of branching fractions R ( D * ) = B ( B Β― β†’ D * Ο„ βˆ’ Ξ½ Β― Ο„ ) / B ( B Β― β†’ D * β„“ βˆ’ Ξ½ Β― β„“ ) , where β„“ is an electron or muon, is measured using a Belle II data sample with an integrated luminosity of 189 fb βˆ’ 1 at the SuperKEKB asymmetric-energy e + e βˆ’ collider. Data is collected at the Ο’ ( 4 S ) resonance, and one B meson in the Ο’ ( 4 S ) β†’ B B Β― decay is fully reconstructed in hadronic decay modes. The accompanying signal B meson is reconstructed as B Β― β†’ D * Ο„ βˆ’ Ξ½ Β― Ο„ using leptonic Ο„ decays. The normalization decay, B Β― β†’ D * β„“ βˆ’ Ξ½ Β― β„“ , produces the same observable final-state particles. The ratio of branching fractions is extracted in a simultaneous fit to two signal-discriminating variables in both channels and yields R ( D * ) = 0.262 βˆ’ 0.039 + 0.041 ( stat ) βˆ’ 0.032 + 0.035 ( syst ) . This result is consistent with the current world average and with Standard Model predictions. Published by the American Physical Society 2024

Adachi, I. (ORCID:0000000322870173)β†—
DOE OSTI2024

Angular analysis of B β†’ K * e + e βˆ’ in the low- q 2 region with new electron identification at Belle

We perform an angular analysis of the B β†’ K * e + e βˆ’ decay for the dielectron mass squared, q 2 , range of 0.0008 – 1.1200 GeV 2 / c 4 using the full Belle dataset in the K * 0 β†’ K + Ο€ βˆ’ and K * + β†’ K S 0 Ο€ + channels, incorporating new methods of electron identification to improve the statistical power of the dataset. This analysis is sensitive to contributions from right-handed currents from physics beyond the Standard Model by constraining the Wilson coefficients C 7 ( β€² ) . We perform a fit to the B β†’ K * e + e βˆ’ differential decay rate and measure the imaginary component of the transversality amplitude to be A T Im = βˆ’ 1.27 Β± 0.52 Β± 0.12 , and the K * transverse asymmetry to be A T ( 2 ) = 0.52 Β± 0.53 Β± 0.11 , with F L and A T Re fixed to the Standard Model values. The resulting constraints on the value of C 7 β€² are consistent with the Standard Model within a 2 Οƒ confidence interval. Published by the American Physical Society 2024

Ferlewicz, D. (ORCID:0000000243741234)β†—
DOE OSTI2024

Measurement of Angular Coefficients of B Β― β†’ D * β„“ Ξ½ Β― β„“ : Implications for | V c b | and Tests of Lepton Flavor Universality

We measure the complete set of angular coefficients J i for exclusive B Β― β†’ D * β„“ Ξ½ Β― β„“ decays ( β„“ = e , ΞΌ ). Our analysis uses the full 711 fb βˆ’ 1 Belle dataset with hadronic tag-side reconstruction. The results allow us to extract the form factors describing the B Β― β†’ D * transition and the Cabibbo-Kobayashi-Maskawa matrix element | V cb | . Using recent lattice QCD calculations for the hadronic form factors, we find | V cb | = ( 40.7 Β± 0.7 ) Γ— 10 βˆ’ 3 using the Boyd-Grinstein-Lebed parametrization, compatible with determinations from inclusive semileptonic decays. We search for lepton flavor universality violation as a function of the hadronic recoil parameter w and investigate the differences of the electron and muon angular distributions. We find no deviation from standard model expectations. Published by the American Physical Society 2024

Physics↗
DOE OSTI2024

Search for lepton-flavor-violating Ο„ – β†’ ΞΌ – ΞΌ + ΞΌ – decays at Belle II

We present the result of a search for the charged-lepton-flavor violating decay Ο„ – β†’ ΞΌ – ΞΌ + ΞΌ – using a 424 fb –1 sample of data recorded by the Belle II experiment at the SuperKEKB e + e – collider. The selection of e + e – β†’ Ο„ + Ο„ – events is based on an inclusive reconstruction of the non-signal tau decay, and on a boosted decision tree to suppress background. We observe one signal candidate, which is compatible with the expectation from background processes. We set a 90% confidence level upper limit of 1.9 Γ— 10 –8 on the branching fraction of the Ο„ – β†’ ΞΌ – ΞΌ + ΞΌ – decay, which is the most stringent bound to date.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Search for Rare b β†’ d β„“ + β„“ βˆ’ Transitions at Belle

We present the results of a search for the b β†’ d β„“ + β„“ βˆ’ flavor-changing neutral-current rare decays B + , 0 β†’ ( Ξ· , Ο‰ , Ο€ + , 0 , ρ + , 0 ) e + e βˆ’ and B + , 0 β†’ ( Ξ· , Ο‰ , Ο€ 0 , ρ + ) ΞΌ + ΞΌ βˆ’ using a 711 fb βˆ’ 1 data sample that contains 772 Γ— 10 6 B B Β― events. The data were collected at the Ο’ ( 4 S ) resonance with the Belle detector at the KEKB asymmetric-energy e + e βˆ’ collider. We find no evidence for signal and set upper limits on branching fractions at the 90% confidence level in the range ( 3.8 – 47 ) Γ— 10 βˆ’ 8 depending on the decay channel. The obtained limits are the world’s best results. This is the first search for the channels B + , 0 β†’ ( Ο‰ , ρ + , 0 ) e + e βˆ’ and B + , 0 β†’ ( Ο‰ , ρ + ) ΞΌ + ΞΌ βˆ’ . Published by the American Physical Society 2024

Physics↗
DOE OSTI2024

Search for charmed baryons in the Ξ› c + Ξ· system and measurement of the branching fractions of Ξ› c ( 2880 ) + and Ξ› c ( 2940 ) + decaying to Ξ› c + Ξ· and p D 0 relative to Ξ£ c ( 2455 ) Ο€

We search for excited charmed baryons in the Ξ› c + Ξ· system using a data sample corresponding to an integrated luminosity of 980 fb βˆ’ 1 . The data were collected by the Belle detector at the KEKB e + e βˆ’ asymmetric-energy collider. No significant signals are found in the Ξ› c + Ξ· mass spectrum, including the known Ξ› c ( 2880 ) + and Ξ› c ( 2940 ) + . Clear Ξ› c ( 2880 ) + and Ξ› c ( 2940 ) + signals are observed in the p D 0 mass spectrum. We set upper limits at 90% credibility level on ratios of branching fractions of Ξ› c ( 2880 ) + and Ξ› c ( 2940 ) + decaying to Ξ› c + Ξ· relative to Ξ£ c ( 2455 ) Ο€ of < 0.13 for the Ξ› c ( 2880 ) + and < 1.11 for the Ξ› c ( 2940 ) + . We measure ratios of branching fractions of Ξ› c ( 2880 ) + and Ξ› c ( 2940 ) + decaying to p D 0 relative to Ξ£ c ( 2455 ) Ο€ of 0.75 Β± 0.03 ( stat ) Β± 0.07 ( syst ) for the Ξ› c ( 2880 ) + and 3.59 Β± 0.21 ( stat ) Β± 0.56 ( syst ) for the Ξ› c ( 2940 ) + . Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Search for the decay B 0 β†’ Ξ³ Ξ³ using Belle and Belle II data

We report the result of a search for the rare decay B 0 β†’ Ξ³ Ξ³ using a combined dataset of 753 Γ— 10 6 B B Β― pairs collected by the Belle experiment and 387 Γ— 10 6 B B Β― pairs collected by the Belle II experiment from decays of the Ο’ ( 4 S ) resonance produced in e + e βˆ’ collisions. A simultaneous fit to the Belle and Belle II data sets yields 11.0 βˆ’ 5.5 + 6.5 signal events, corresponding to a 2.5 Οƒ significance. We determine the branching fraction B ( B 0 β†’ Ξ³ Ξ³ ) = ( 3.7 βˆ’ 1.8 + 2.2 ( stat ) Β± 0.5 ( syst ) ) Γ— 10 βˆ’ 8 and set a 90% credibility level upper limit of B ( B 0 β†’ Ξ³ Ξ³ ) < 6.4 Γ— 10 βˆ’ 8 . Published by the American Physical Society 2024

Adachi, I. (ORCID:0000000322870173)β†—
DOE OSTI2024

Measurements of the Branching Fraction, Polarization, and C P Asymmetry for the Decay B 0 β†’ Ο‰ Ο‰

We present a comprehensive study of B 0 β†’ Ο‰ Ο‰ decays using 772 Γ— 10 6 B B Β― pairs collected with the Belle detector at the KEKB e + e βˆ’ collider. This process is a suppressed charmless decay into two vector mesons and can exhibit interesting polarization and C P 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 Β± 0.29 Β± 0.17 ) Γ— 10 βˆ’ 6 , a fraction of longitudinal polarization f L = 0.87 Β± 0.13 Β± 0.13 , and a time-integrated C P asymmetry A C P = βˆ’ 0.44 Β± 0.43 Β± 0.11 , where the first uncertainties listed are statistical and the second are systematic. This is the first observation of B 0 β†’ Ο‰ Ο‰ and the first measurements of f L and A C P for this decay. Published by the American Physical Society 2024

Physics↗
DOE OSTI2024

Search for Baryon-Number-Violating Processes in B βˆ’ Decays to the Ξ Β― c 0 Ξ› Β― c βˆ’ Final State

We report the results of the first search for B βˆ’ decays to the Ξ Β― c 0 Ξ› Β― c βˆ’ final state using 711 fb βˆ’ 1 of data collected at the Ο’ ( 4 S ) resonance with the Belle detector at the KEKB asymmetric-energy e + e βˆ’ collider. The results are interpreted in terms of both direct baryon-number-violating B βˆ’ decay and Ξ c 0 βˆ’ Ξ Β― c 0 oscillations which follow the standard model decay B βˆ’ β†’ Ξ c 0 Ξ› Β― c βˆ’ . 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 βˆ’ β†’ Ξ Β― c 0 Ξ› Β― c βˆ’ ) / B ( B βˆ’ β†’ Ξ c 0 Ξ› Β― c βˆ’ ) to be < 2.7 % and on the effective angular frequency of mixing Ο‰ in Ξ c 0 βˆ’ Ξ Β― c 0 oscillations to be < 0.76 ps βˆ’ 1 (equivalent to Ο„ mix > 1.3 ps ). Published by the American Physical Society 2024

Physics↗
DOE OSTI2024

Measurement of the branching fractions of $$ \overline{B} $$ β†’ D(*)Kβˆ’$$ {K}_{(S)}^{\left(\ast \right)0} $$ and $$ \overline{B} $$ β†’ D(*)$$ {D}_s^{-} $$ decays at Belle II

Abstract We present measurements of the branching fractions of eight$$ {\overline{B}}^0 $$ B Β― 0 β†’D (*)+ K βˆ’ $$ {K}_{(S)}^{\left(\ast \right)0} $$ K S βˆ— 0 ,B βˆ’ β†’D (*)0 K βˆ’ $$ {K}_{(S)}^{\left(\ast \right)0} $$ K S βˆ— 0 decay channels. The results are based on data from SuperKEKB electron-positron collisions at the Ξ₯(4S) resonance collected with the Belle II detector, corresponding to an integrated luminosity of 362 fb βˆ’1 . The event yields are extracted from fits to the distributions of the difference between expected and observedBmeson energy, and are efficiency-corrected as a function ofm(K βˆ’ $$ {K}_{(S)}^{\left(\ast \right)0} $$ K S βˆ— 0 ) andm(D (*) $$ {K}_{(S)}^{\left(\ast \right)0} $$ K S βˆ— 0 ) in order to avoid dependence on the decay model. These results include the first observation of$$ {\overline{B}}^0 $$ B Β― 0 β†’D + K βˆ’ $$ {K}_S^0 $$ K S 0 ,B βˆ’ β†’D* 0 K βˆ’ $$ {K}_S^0 $$ K S 0 , and$$ {\overline{B}}^0 $$ B Β― 0 β†’D* + K βˆ’ $$ {K}_S^0 $$ K S 0 decays and a significant improvement in the precision of the other channels compared to previous measurements. The helicity-angle distributions and the invariant mass distributions of theK βˆ’ $$ {K}_{(S)}^{\left(\ast \right)0} $$ K S βˆ— 0 systems are compatible with quasi-two-body decays via a resonant transition with spin-parityJ P = 1 βˆ’ for theK βˆ’ $$ {K}_S^0 $$ K S 0 systems andJ P = 1 + for theK βˆ’ K* 0 systems. We also present measurements of the branching fractions of four$$ {\overline{B}}^0 $$ B Β― 0 β†’D (*)+ $$ {D}_s^{-} $$ D s βˆ’ ,B βˆ’ β†’D (*)0 $$ {D}_s^{-} $$ D s βˆ’ decay channels with a precision compatible to the current world averages.

Physics↗
DOE OSTI2024

New graph-neural-network flavor tagger for Belle II and measurement of sin 2β’πœ™ 1 in 𝐡 0 β†’ 𝐽/πœ“β’πΎ$^0_ S$ decays

We present GFlaT, a new algorithm that uses a graph-neural-network to determine the flavor of neutral 𝐡 mesons produced in ϒ⁑(4⁒𝑆) decays. It improves previous algorithms by using the information from all charged final-state particles and the relations between them. We evaluate its performance using 𝐡 decays to flavor-specific hadronic final states reconstructed in a 362 fb βˆ’1 sample of electron-positron collisions collected at the ϒ⁑(4⁒𝑆) resonance with the Belle II detector at the SuperKEKB collider. We achieve an effective tagging efficiency of (37.40 Β± 0.43 Β± 0.36%), where the first uncertainty is statistical and the second systematic, which is 18% better than the previous Belle II algorithm. Demonstrating the algorithm, we use 𝐡 0 →𝐽/πœ“β’πΎ$^0_ S$ decays to measure the mixing-induced and direct 𝐢⁒𝑃 violation parameters, 𝑆 = (0.724 Β± 0.035 Β± 0.009) and 𝐢 = (βˆ’0.035 Β± 0.026 Β± 0.029).

CP violation↗
DOE OSTI2024

Study of Ξ₯(10753) decays to Ο€+Ο€βˆ’Ξ₯(nS) final states at Belle II

Abstract We present an analysis of the processe + e βˆ’ β†’Ο€ + Ο€ βˆ’ Ξ₯(nS) (wheren= 1, 2, or 3) reconstructed in 19.6 fb βˆ’1 of Belle II data during a special run of the SuperKEKB collider at four energy points near the peak of the Ξ₯(10753) resonance. By analyzing the mass distribution of theΟ€ + Ο€ βˆ’ Ξ₯(nS) system and the Born cross sections of thee + e βˆ’ β†’Ο€ + Ο€ βˆ’ Ξ₯(nS) process, we report the first observation of Ξ₯(10753) decays to theΟ€ + Ο€ βˆ’ Ξ₯(1S) andΟ€ + Ο€ βˆ’ Ξ₯(2S) final states, and find no evidence for decays toΟ€ + Ο€ βˆ’ Ξ₯(3S). Possible intermediate states in theΟ€ + Ο€ βˆ’ Ξ₯(1S,2S) transitions are also investigated, and no evidence for decays proceeding via the$$ {\pi}^{\mp }{Z}_b^{\pm } $$ Ο€ βˆ“ Z b Β± orf 0 (980)Ξ₯(nS) intermediate states is found. We measure Born cross sections for thee + e βˆ’ β†’Ο€ + Ο€ βˆ’ Ξ₯(nS) process that, combined with results from Belle, obtain the mass and width of Ξ₯(10753) to be (10756.6 Β± 2.7 Β± 0.9) MeV/c 2 and (29.0 Β± 8.8 Β± 1.2) MeV, respectively. The relative ratios of the Born cross sections at the Ξ₯(10753) resonance peak are also reported for the first time.

Physics↗
DOE OSTI2024

Measurement of the branching fraction of the decay B βˆ’ β†’ D 0 ρ ( 770 ) βˆ’ at Belle II

We measure the branching fraction of the decay B βˆ’ β†’ D 0 ρ ( 770 ) βˆ’ using data collected with the Belle II detector. The data contain 387 million B B Β― pairs produced in e + e βˆ’ collisions at the Ο’ ( 4 S ) resonance. We reconstruct 8360 Β± 180 decays from an analysis of the distributions of the B βˆ’ energy and the ρ ( 770 ) βˆ’ helicity angle. We determine the branching fraction to be ( 0.939 Β± 0.021 ( stat ) Β± 0.050 ( syst ) ) % , in agreement with previous results. Our measurement improves the relative precision of the world average by more than a factor of two. Published by the American Physical Society 2024

Astronomy & Astrophysics↗