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Garg, R. (ORCID:0000000274064707)

Publications and source records attributed to Garg, R. (ORCID:0000000274064707).

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

Measurements of the branching fractions of ${\Xi }_{c}^{+}\to {\Sigma }^{+}{K}_{S}^{0}$, ${\Xi }_{c}^{+}\to {\Xi }^{0}{\pi }^{+}$, and ${\Xi }_{c}^{+}\to {\Xi }^{0}{K}+$ at Belle and Belle II

Using 983.0 fb βˆ’1 and 427.9 fb βˆ’1 data samples collected with the Belle and Belle II detectors at the KEKB and SuperKEKB asymmetric energy e + e βˆ’ colliders, respectively, we present studies of the Cabibbo-favored ${\Xi }_{c}^{+}$ decays ${\Xi }_{c}^{+}\to {\Sigma }^{+}{K}_{S}^{0}$ and ${\Xi }_{c}^{+}\to {\Xi }^{0}{\pi }^{+}$, and the singly Cabibbo-suppressed decay ${\Xi }_{c}^{+}\to {\Xi }^{0}{K}^{+}$. The ratios of branching fractions of ${\Xi }_{c}^{+}\to {\Sigma }^{+}{K}_{S}^{0}$ and ${\Xi }_{c}^{+}\to {\Xi }^{0}{K}^{+}$ relative to that of ${\Xi }_{c}^{+}\to {\Xi }^{-}{\pi }^{+}{\pi }^{+}$ are measured for the first time, while the ratio $\mathcal{B}({\Xi }_{c}^{+}\to {\Xi }^{0}{\pi }^{+})/\mathcal{B}({\Xi }_{c}^{+}\to {\Xi }^{-}{\pi }^{+}{\pi }^{+})$ is also determined and improved by an order of magnitude in precision. The measured branching fraction ratios are $\begin{array}{c}\frac{\mathcal{B}\left({\Xi }_{c}^{+}\to {\Sigma }^{+}{K}_{S}^{0}\right)}{\mathcal{B}\left({\Xi }_{c}^{+}\to {\Xi }^{-}{\pi }^{+}{\pi }^{+}\right)}=0.067\pm 0.007\pm 0.003,\\ \frac{\mathcal{B}\left({\Xi }_{c}^{+}\to {\Xi }^{0}{\pi }^{+}\right)}{\mathcal{B}\left({\Xi }_{c}^{+}\to {\Xi }^{-}{\pi }^{+}{\pi }^{+}\right)}=0.251\pm 0.005\pm 0.010,\\ \frac{\mathcal{B}\left({\Xi }_{c}^{+}\to {\Xi }^{0}{K}^{+}\right)}{\mathcal{B}\left({\Xi }_{c}^{+}\to {\Xi }^{-}{\pi }^{+}{\pi }^{+}\right)}=0.017\pm 0.003\pm 0.001.\end{array}$ Additionally, the ratio $\mathcal{B}({\Xi }_{c}^{+}\to {\Xi }^{0}{K}^{+})/\mathcal{B}({\Xi }_{c}^{+}\to {\Xi }^{0}{\pi }^{+})$ is measured to be 0.068 Β± 0.010 Β± 0.004. Here, the first and second uncertainties are statistical and systematic, respectively. Multiplying the ratios by the branching fraction of the normalization mode, $\mathcal{B}({\Xi }_{c}^{+}\to {\Xi }^{-}{\pi }^{+}{\pi }^{+})=(2.9\pm 1.3)%$, we obtain the following absolute branching fractions $\begin{array}{c}\mathcal{B}({\Xi }_{c}^{+}\to {\Sigma }^{+}{K}_{S}^{0})=(0.194\pm 0.021\pm 0.009\pm 0.087)\text{%},\\ \mathcal{B}({\Xi }_{c}^{+}\to {\Xi }^{0}{\pi }^{+})=(0.728\pm 0.014\pm 0.027\pm 0.326)\text{%},\\ \mathcal{B}({\Xi }_{c}^{+}\to {\Xi }^{0}{K}^{+})=(0.049\pm 0.007\pm 0.003\pm 0.022)\text{%},\end{array}$ where the third uncertainties are from $\mathcal{B}({\Xi }_{c}^{+}\to {\Xi }^{-}{\pi }^{+}{\pi }^{+})$.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
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

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 OSTI2025

Measurement of the time-integrated 𝐢⁒𝑃 asymmetry in 𝐷 0 β†’ πœ‹ 0 β’πœ‹ 0 decays at Belle II

We measure the time-integrated 𝐢⁒𝑃 asymmetry, 𝐴 𝐢⁒𝑃 , in 𝐷 0 β†’ πœ‹ 0 β’πœ‹ 0 decays reconstructed in 𝑒 + ⁒𝑒 βˆ’ β†’ $𝑐⁒\bar{𝑐}$ events collected by Belle II during 2019–2022. The data corresponds to an integrated luminosity of 428 fb βˆ’1 . The 𝐷 0 decays are required to originate from the flavor-conserving 𝐷 *+ β†’ 𝐷 0 β’πœ‹ + decay to determine the charm flavor at production time. Control samples of 𝐷 0 β†’ 𝐾 βˆ’ β’πœ‹ + decays, with or without an associated pion from a 𝐷 *+ decay, are used to correct for detection asymmetries. The result, 𝐴 𝐢⁒𝑃 ⁑(𝐷 0 β†’ πœ‹ 0 β’πœ‹ 0 ) = (0.30 Β± 0.72 Β± 0.20)%, where the first uncertainty is statistical and the second systematic, is consistent with 𝐢⁒𝑃 symmetry.

CP violation↗
DOE OSTI2025

Model-independent measurement of 𝐷 0 βˆ’$\overline{D}$ 0 mixing parameters in 𝐷 0 β†’ 𝐾$^{0}_{𝑆}$β’πœ‹ + β’πœ‹ βˆ’ decays at Belle and Belle II

We perform a model-independent measurement of the 𝐷 0 βˆ’$\overline{D}$ 0 mixing parameters using samples of 𝑒 + ⁒𝑒 βˆ’ -collision data collected by the Belle and Belle II experiments that have integrated luminosities of 951 fb βˆ’1 and 408 fb βˆ’1 , respectively. Approximately 2.05 Γ— 10 6 neutral 𝐷 mesons are reconstructed in the 𝐷 0 β†’ 𝐾$^{0}_{S}$β’πœ‹ + β’πœ‹ βˆ’ channel, with the neutral 𝐷 flavor tagged by the charge of the pion in the 𝐷* + β†’ 𝐷 0⁒ πœ‹ + decay. Assuming charge-parity symmetry, the mixing parameters are measured to be π‘₯ = (4.0 Β±1.7 Β±0.4) Γ— 10 βˆ’3 and 𝑦 = (2.9 Β±1.4 Β±0.3) Γ— 10 βˆ’3 , where the first uncertainties are statistical and the second systematic. The results are consistent with previous determinations.

Charmed mesons↗
DOE OSTI2025

Measurement of the branching fraction, polarization, and time-dependent C P asymmetry in B 0 β†’ ρ + ρ βˆ’ decays and constraint on the CKM angle Ο• 2

We present a measurement of the branching fraction and fraction of longitudinal polarization of B 0 β†’ ρ + ρ βˆ’ decays, which have two Ο€ 0 ’s in the final state. We also measure time-dependent C P violation parameters for decays into longitudinally polarized ρ + ρ βˆ’ pairs. This analysis is based on a data sample containing ( 387 Β± 6 ) Γ— 10 6 Ο’ ( 4 S ) mesons collected with the Belle II detector at the SuperKEKB asymmetric-energy e + e βˆ’ collider in 2019–2022. We obtain B ( B 0 β†’ ρ + ρ βˆ’ ) = ( 2.8 9 βˆ’ 0.22 + 0.23 βˆ’ 0.27 + 0.29 ) Γ— 10 βˆ’ 5 , f L = 0.92 1 βˆ’ 0.025 + 0.024 βˆ’ 0.015 + 0.017 , S = βˆ’ 0.26 Β± 0.19 Β± 0.08 , and C = βˆ’ 0.02 Β± 0.1 2 βˆ’ 0.05 + 0.06 , where the first uncertainties are statistical and the second are systematic. We use these results to perform an isospin analysis to constrain the Cabibbo-Kobayashi-Maskawa angle Ο• 2 and obtain two solutions; the result consistent with other Standard Model constraints is Ο• 2 = ( 92.6 βˆ’ 4.7 + 4.5 ) Β° . 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

Evidence of h b ( 2 P ) β†’ Ο’ ( 1 S ) Ξ· Decay and Search for h b ( 1 P , 2 P ) β†’ Ο’ ( 1 S ) Ο€ 0 with the Belle Detector

We report the first evidence for the h b ( 2 P ) β†’ Ο’ ( 1 S ) Ξ· transition with a significance of 3.5 standard deviations. The decay branching fraction is measured to be B [ h b ( 2 P ) β†’ Ο’ ( 1 S ) Ξ· ] = ( 7.1 βˆ’ 3.2 + 3.7 Β± 0.8 ) Γ— 10 βˆ’ 3 , which is noticeably smaller than expected. We also set upper limits on Ο€ 0 transitions of B [ h b ( 2 P ) β†’ Ο’ ( 1 S ) Ο€ 0 ] < 1.8 Γ— 10 βˆ’ 3 , and B [ h b ( 1 P ) β†’ Ο’ ( 1 S ) Ο€ 0 ] < 1.8 Γ— 10 βˆ’ 3 , at the 90% confidence level. These results are obtained with a 131.4 fb βˆ’ 1 data sample collected near the Ο’ ( 5 S ) resonance with the Belle detector at the KEKB asymmetric-energy e + e βˆ’ collider. Published by the American Physical Society 2024

Kovalenko, E. (ORCID:0000000180841931)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

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

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 OSTI2024

Search for the semileptonic decays Ξ c 0 β†’ Ξ 0 β„“ + β„“ βˆ’ at Belle

Using the full data sample of 980 fb βˆ’ 1 collected with the Belle detector at the KEKB asymmetric energy electron-positron collider, we report the results of the first search for the rare semileptonic decays Ξ c 0 β†’ Ξ 0 β„“ + β„“ βˆ’ ( β„“ = e or ΞΌ ). No significant signals are observed in the Ξ 0 β„“ + β„“ βˆ’ invariant-mass distributions. Taking the decay Ξ c 0 β†’ Ξ βˆ’ Ο€ + as the normalization mode, we report 90% credibility upper limits on the branching fraction ratios B ( Ξ c 0 β†’ Ξ 0 e + e βˆ’ ) / B ( Ξ c 0 β†’ Ξ βˆ’ Ο€ + ) < 6.7 Γ— 10 βˆ’ 3 and B ( Ξ c 0 β†’ Ξ 0 ΞΌ + ΞΌ βˆ’ ) / B ( Ξ c 0 β†’ Ξ βˆ’ Ο€ + ) < 4.3 Γ— 10 βˆ’ 3 based on the phase-space assumption for signal decays. The 90% credibility upper limits on the absolute branching fractions of B ( Ξ c 0 β†’ Ξ 0 e + e βˆ’ ) and B ( Ξ c 0 β†’ Ξ 0 ΞΌ + ΞΌ βˆ’ ) are found to be 9.9 Γ— 10 βˆ’ 5 and 6.5 Γ— 10 βˆ’ 5 , respectively. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Search for the decay B s 0 β†’ J / ψ Ο€ 0 at Belle experiment

We have analyzed 121.4 fb βˆ’ 1 of data collected at the Ο’ ( 5 S ) resonance by the Belle experiment using the KEKB asymmetric-energy e + e βˆ’ collider to search for the decay B s 0 β†’ J / ψ Ο€ 0 . We observe no signal and report an upper limit on the branching fraction B ( B s 0 β†’ J / ψ Ο€ 0 ) of 1.21 Γ— 10 βˆ’ 5 at 90% confidence level. This result is the most stringent, improving the previous bound by 2 orders of magnitude. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Search for baryon and lepton number violating decays D β†’ p β„“

We search for the baryon and lepton number violating charm decays, D β†’ p β„“ , where D is either a D 0 or a D Β― 0 and β„“ is a muon or an electron, using a data sample of 921 fb βˆ’ 1 collected by the Belle detector at the KEKB asymmetric energy e + e βˆ’ collider. In the absence of significant signals, we set upper limits on the branching fractions in the range ( 5 – 8 ) Γ— 10 βˆ’ 7 at a 90% confidence level, depending on the decay mode. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2023

Observation of a threshold cusp at the Ξ› Ξ· threshold in the pK - mass spectrum with Ξ›$^{+}_{c}$ β†’ pK - Ο€ + decays

We observe a narrow peaking structure in the pK - invariant-mass spectrum near the Λη threshold. The peak is clearly seen in 1.5 million events of Ξ›$^{+}_{c}$ β†’ pK - Ο€ + decay using the 980 fb -1 data sample collected by the Belle detector at the KEKB asymmetric-energy e + e - collider. We try two approaches to explain this structure: as a new resonance and as a cusp at the Λη threshold. The best fit is obtained with a coherent sum of a Flatte function and a constant background amplitude with the reduced X 2 of 257/243 (p = 0.25), while the fits to Breit-Wigner functions are unfavored by more than 7Οƒ. The best fit explains the structure as a cusp at the Λη threshold, and the obtained parameters are consistent with the known properties of Ξ›(1670). The observation gives the first identification of a threshold cusp in hadrons from the spectrum shape.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗