Search NASAβŒ• Search

Engineering topics

de Marino, G. (ORCID:0000000265097793)

Publications and source records attributed to de Marino, G. (ORCID:0000000265097793).

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Model-agnostic likelihood for the reinterpretation of the 𝐡 + β†’ 𝐾 + ⁒$𝑣\bar{𝑣}$ measurement at Belle II

We recently measured the branching fraction of the 𝐡 + β†’ 𝐾 + ⁒$𝑣\bar{𝑣}$ decay using 362 fb βˆ’1 of on-resonance 𝑒 + ⁒𝑒 βˆ’ collision data under the assumption of Standard Model kinematics, providing the first evidence for this decay. To facilitate future reinterpretations and maximize the scientific impact of this measurement, we publicly release the full analysis likelihood along with all necessary material required for reinterpretation under arbitrary theoretical models sensitive to this measurement. In this work, we demonstrate how the measurement can be reinterpreted within the framework of the weak effective theory. Using a kinematic reweighting technique in combination with the published likelihood, we derive marginal posterior distributions for the Wilson coefficients, construct credible intervals, and assess the goodness of fit to the Belle II data. For the weak effective theory Wilson coefficients, the posterior mode of the magnitudes |𝐢 VL +𝐢 VR |, |𝐢 SL +𝐢 SR |, and |𝐢 TL | corresponds to the point (11.3, 0.0, 8.2). The respective 95% credible intervals are [1.9, 16.2], [0.0, 15.4], and [0.0, 11.2].

bottom quark↗
DOE OSTI2025

Measurement of the 𝐷 0 →𝐾 βˆ’ β’πœ‹ + ⁒𝑒 + ⁒𝑒 βˆ’ branching fraction and search for 𝐷 0 β†’ πœ‹ + β’πœ‹ βˆ’ ⁒𝑒 + ⁒𝑒 βˆ’ and 𝐷 0 →𝐾 + ⁒𝐾 βˆ’ ⁒𝑒 + ⁒𝑒 βˆ’ decays at Belle

We present a study of the rare charm meson decays 𝐷 0 →𝐾 + ⁒𝐾 βˆ’ ⁒𝑒 + ⁒𝑒 βˆ’ , πœ‹ + β’πœ‹ βˆ’ ⁒𝑒 + ⁒𝑒 βˆ’ , and 𝐾 βˆ’ β’πœ‹ + ⁒𝑒 + ⁒𝑒 βˆ’ using a 942 fb βˆ’1 dataset collected by the Belle detector at the KEKB asymmetric-energy 𝑒 + ⁒𝑒 βˆ’ collider. We identify 𝐷 0 candidates via the charge of the pion from 𝐷* + →𝐷 0 β’πœ‹ + decays and normalize the branching fractions to 𝐷 0 β†’ 𝐾 βˆ’ β’πœ‹ + β’πœ‹ βˆ’ β’πœ‹ + decays. The branching fraction for decay 𝐷 0 β†’ 𝐾 βˆ’ β’πœ‹ + ⁒𝑒 + ⁒𝑒 βˆ’ is measured to be (39.6 Β± 4.5 (stat) Β± 2.9 (syst)) Γ— 10 βˆ’7 , with the dielectron mass in the 𝜌/πœ” mass region 675 < π‘š 𝑒⁒𝑒 < 875 MeV/⁒𝑐 2 . We also search for 𝐷 0 β†’ β„Ž βˆ’ β‘β„Ž (β€²)+ ⁑𝑒 + ⁒𝑒 βˆ’ (β„Ž (β€²) = 𝐾, πœ‹) decays with the dielectron mass near the πœ‚ and πœ™ resonances, and away from these resonances for the 𝐾 + ⁒𝐾 βˆ’ ⁒𝑒 + ⁒𝑒 βˆ’ and πœ‹ + β’πœ‹ βˆ’ ⁒𝑒 + ⁒𝑒 βˆ’ modes. For these modes, we find no significant signals and set 90% confidence level upper limits on their branching fractions at the π’ͺ⁑(10 βˆ’7 ) level.

branching fraction↗
DOE OSTI2025

Search for B 0 β†’ K *0 𝜏 + ⁒𝜏 βˆ’ Decays at the Belle II Experiment

We present a search for the rare flavor-changing neutral-current decay 𝐡 0 →𝐾 *0 ⁒𝜏 + ⁒𝜏 βˆ’ with data collected by the Belle II experiment at the SuperKEKB electron-positron collider. The analysis uses a 365 fb βˆ’1 data sample recorded at the center-of-mass energy of the ϒ⁑(4⁒𝑆) resonance. One of the 𝐡 mesons produced in the ϒ⁑(4⁒𝑆)→𝐡 0 $⁒\overline{𝐡}$ 0 process is fully reconstructed in a hadronic decay mode, while its companion 𝐡 meson is required to decay into a 𝐾 *0 and two 𝜏 leptons of opposite charge. The 𝜏 leptons are reconstructed in final states with a single electron, muon, charged pion or charged 𝜌 meson, and additional neutrinos. We set an upper limit on the branching fraction of ℬ⁑(𝐡 0 →𝐾 *0 ⁒𝜏 + ⁒𝜏 βˆ’ )<1.8Γ—10 βˆ’3 at the 90% confidence level, which is the most stringent constraint reported to date.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Search for a Dark Higgs Boson Produced in Association with Inelastic Dark Matter at the Belle II Experiment

Inelastic dark matter models that have two dark matter particles and a massive dark photon can reproduce the observed relic dark matter density without violating cosmological limits. The mass splitting between the two dark matter particles πœ’ 1 and πœ’ 2 , with π‘šβ‘(πœ’ 2 ) >π‘šβ‘(πœ’ 1 ), is induced by a dark Higgs field and a corresponding dark Higgs boson β„Žβ€². We present a search for dark matter in events with two vertices, at least one of which must be displaced from the interaction region, and missing energy. Using a 365 fb βˆ’1 data sample collected at Belle II, which operates at the SuperKEKB 𝑒 + ⁒𝑒 βˆ’ collider, we observe no evidence for a signal. We set upper limits on the product of the production cross section 𝜎⁑(𝑒 + ⁒𝑒 βˆ’ β†’ β„Žβ€²β‘πœ’ 1 β’πœ’ 2 ), and the product of branching fractions ℬ⁑(πœ’ 2 β†’ πœ’ 1⁒ 𝑒 + ⁒𝑒 βˆ’ ) ×ℬ⁑(β„Žβ€² β†’ π‘₯ + ⁒π‘₯ βˆ’ ), where π‘₯ + ⁒π‘₯ βˆ’ indicates πœ‡ + β’πœ‡ βˆ’ , πœ‹ + β’πœ‹ βˆ’ , or 𝐾 + ⁒𝐾 βˆ’ , as functions of β„Žβ€² mass and lifetime at the level of 10 βˆ’1 fb. We set model-dependent upper limits on the dark Higgs mixing angle at the level of 10 βˆ’5 and on the dark photon kinetic mixing parameter at the level of 10 βˆ’3 . This is the first search for dark Higgs bosons in association with inelastic dark matter.

dark matter↗
DOE OSTI2025

Search for lepton flavor-violating decay modes B 0 β†’ K* 0 Ο„ Β± β„“ βˆ“ (β„“ = e, ΞΌ) with hadronic B-tagging at Belle and Belle II

We present the results of a search for the charged-lepton-flavor violating decays B 0 β†’ K *0 Ο„ Β± β„“ βˆ“ , where β„“ βˆ“ is either an electron or a muon. The results are based on 365 fb βˆ’1 and 711 fb βˆ’1 datasets collected with the Belle II and Belle detectors, respectively. We use an exclusive hadronic B-tagging technique, and search for a signal decay in the system recoiling against a fully reconstructed B meson. We find no evidence for B 0 β†’ K* 0 Ο„ Β± β„“ βˆ“ decays and set upper limits on the branching fractions in the range of (2.9–6.4)Γ—10 βˆ’5 at 90% confidence level.

B physics↗
DOE OSTI2025

Search for lepton-flavor-violating ${\tau }^{-}\to {{\ell}}^{-}{K}_{s}^{0}$ decays at Belle and Belle II

We present the results of a search for charged-lepton-flavor violating decays ${\tau }^{-}\to {{\ell}}^{-}{K}_{s}^{0}$, where β„“ βˆ’ is either an electron or a muon. We combine e + e βˆ’ data samples recorded by the Belle II experiment at the SuperKEKB collider (428 fb βˆ’1 ) with samples recorded by the Belle experiment at the KEKB collider (980 fb βˆ’1 ) to obtain a sample of 1.3 billion e + e βˆ’ β†’ Ο„ + Ο„ βˆ’ events. We observe 0 and 1 events and set 90% confidence level upper limits of 0.8 Γ— 10 βˆ’8 and 1.2 Γ— 10 βˆ’8 on the branching fractions of the decay modes ${\tau }^{-}\to {e}^{-}{K}_{S}^{0}$ and ${\tau }^{-}\to {\mu }^{-}{K}_{S}^{0}$, respectively. These are the most stringent upper limits to date.

beyond Standard Model↗
DOE OSTI2025

Search for Lepton-Flavor-Violating Decay Modes 𝐡 0 →𝐾$^0_𝑆$⁒𝜏 Β± ⁒ℓ βˆ“ with Hadronic 𝐡 Tagging at Belle and Belle II

We present the first search for the lepton-flavor-violating decay modes 𝐡 0 →𝐾$^0_𝑆$⁒𝜏 Β± ⁒ℓ βˆ“ (β„“=πœ‡,𝑒) using the 711 and 365 fb βˆ’1 data samples recorded by the Belle and Belle II detectors, respectively. We use a hadronic 𝐡-tagging technique to fully reconstruct a 𝐡 meson and search for signal decays in the system recoiling against the tagged meson, considering 𝜏 decays to either light leptons, one charged hadron, or one charged hadron and a neutral pion. We find no evidence for 𝐡 0 →𝐾$^0_𝑆$⁒𝜏 Β± ⁒ℓ βˆ“ decays and set 90% confidence level upper limits on the branching fractions in the range of [0.8,3.6] Γ—10 βˆ’5 .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Measurement of the time-integrated 𝐢⁒𝑃 asymmetry in 𝐷 0 β†’ 𝐾$^{0}_{S}$𝐾$^{0}_{S}$ decays using opposite-side flavor tagging at Belle and Belle II

We measure the time-integrated 𝐢⁒𝑃 asymmetry in 𝐷 0 β†’ 𝐾$^{0}_{S}$𝐾$^{0}_{S}$ decays reconstructed in 𝑒 + ⁒𝑒 βˆ’ β†’ $c\bar{c}$ events collected by the Belle and Belle II experiments. The corresponding data samples have integrated luminosities of 980 and 428 fb βˆ’1 , respectively. To infer the flavor of the 𝐷 0 meson, we exploit the correlation between the flavor of the reconstructed decay and the electric charges of particles reconstructed in the rest of the 𝑒 + ⁒𝑒 βˆ’ β†’ $c\bar{c}$ event. This results in a sample which is independent from any other previously used at Belle or Belle II. The result, 𝐴 𝐢⁒𝑃 ⁑(𝐷 0 β†’ 𝐾$^{0}_{S}$𝐾$^{0}_{S}$)=(1.3Β±2.0Β±0.2)%, where the first uncertainty is statistical and the second systematic, is consistent with previous determinations and with 𝐢⁒𝑃 symmetry.

CP violation↗
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

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

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

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

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↗
DOE OSTI2024

First Measurement of R ( X Ο„ / β„“ ) as an Inclusive Test of the b β†’ c Ο„ Ξ½ Anomaly

We measure the tau-to-light-lepton ratio of inclusive B -meson branching fractions R ( X Ο„ / β„“ ) ≑ B ( B β†’ X Ο„ Ξ½ ) / B ( B β†’ X β„“ Ξ½ ) , where β„“ indicates an electron or muon, and thereby test the universality of charged-current weak interactions. We select events that have one fully reconstructed B meson and a charged lepton candidate from 189 fb βˆ’ 1 of electron-positron collision data collected with the Belle II detector. We find R ( X Ο„ / β„“ ) = 0.228 Β± 0.016 ( stat ) Β± 0.036 ( syst ) , in agreement with standard-model expectations. This is the first direct measurement of R ( X Ο„ / β„“ ) . Published by the American Physical Society 2024

Physics↗
DOE OSTI2023

First Simultaneous Determination of Inclusive and Exclusive | V u b |

The first simultaneous determination of the absolute value of the Cabibbo-Kobayashi-Maskawa matrix element V ub using inclusive and exclusive decays is performed with the full Belle data set at the $Ξ₯$(4S) resonance, corresponding to an integrated luminosity of 711 fb -1 . We analyze collision events in which one B meson is fully reconstructed in hadronic modes. This allows for the reconstruction of the hadronic X u system of the semileptonic b β†’ $Ο€β„“e_β„“$ decay. We separate exclusive B β†’ $Ο€β„“\overline{Ξ½}_β„“$ decays from other inclusive B β†’ $X_uβ„“\overline{Ξ½}_β„“$ and backgrounds with a two-dimensional fit that utilizes the number of charged pions in the X u system and the four-momentum transfer q 2 between the B and X u systems. Combining our measurement with information from lattice QCD and QCD calculations of the inclusive partial rate as well as external experimental information on the shape of the B β†’ $Ο€β„“e_β„“$ form factor, we determine |$V^{excl}_{ub}$| = (3.78 Β± 0.23 Β± 0.16 Β± 0.14) Γ— 10 -3 and |$V^{incl}_{ub}$| = (3.88 Β± 0.20 Β± 0.31 Β± 0.09) x 10 -3 , respectively, with the uncertainties being the statistical error, systematic errors, and theory errors. The ratio of |$V^{excl}_{ub}$|/|$V^{incl}_{ub}$| 0.97 Β± 0.12 is compatible with unity.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Precise Measurement of the D s + Lifetime at Belle II

We measure the lifetime of the $D^+_s$ meson using a data sample of 207 fb -1 collected by the Belle II experiment running at the SuperKEKB asymmetric-energy e + e - collider. The lifetime is determined by fitting the decay-time distribution of a sample of 116 Γ— 10 3 $D^+_s$ β†’ φπ + decays. Our result is Ο„$D^+_s$ = (499.5 Β± 1.7 Β± 0.9) fs, where the first uncertainty is statistical and the second is systematic. This result is significantly more precise than previous measurements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Search for a Ο„ + Ο„ - Resonance in e + e - β†’ ΞΌ + ΞΌ - Ο„ + Ο„ - Events with the Belle II Experiment

We report the first search for a nonstandard-model resonance decaying into $Ο„$ pairs in $e^+e^-$ β†’ $ΞΌ^+ΞΌ^-Ο„^+Ο„^-$ events in the 3.6–10 GeV/c 2 mass range. We use a 62.8 fb -1 sample of $e^+e^-$ collisions collected at a center-of-mass energy of 10.58 GeV by the Belle II experiment at the SuperKEKB collider. The analysis probes three different models predicting a spin-1 particle coupling only to the heavier lepton families, a Higgs-like spin-0 particle that couples preferentially to charged leptons (leptophilic scalar), and an axionlike particle, respectively. We observe no evidence for a signal and set exclusion limits at 90% confidence level on the product of cross section and branching fraction into $Ο„$ pairs, ranging from 0.7 to 24 fb, and on the couplings of these processes. We obtain world-leading constraints on the couplings for the leptophilic scalar model for masses above 6.5 GeV/c 2 and for the axionlike particle model over the entire mass range.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Measurement of C P Violation in B 0 β†’ K S 0 Ο€ 0 Decays at Belle II

We report a measurement of the C P -violating parameters C and S in B 0 β†’ K S 0 Ο€ 0 decays at Belle II using a sample of 387 Γ— 10 6 B B Β― events recorded in e + e βˆ’ collisions at a center-of-mass energy corresponding to the Ο’ ( 4 S ) resonance. These parameters are determined by fitting the proper decay-time distribution of a sample of 415 signal events. We obtain C = βˆ’ 0.0 4 βˆ’ 0.15 + 0.14 Β± 0.05 and S = 0.7 5 βˆ’ 0.23 + 0.20 Β± 0.04 , where the first uncertainties are statistical and the second are systematic. Published by the American Physical Society 2023

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗