Engineering topics

Kuhr, T. (ORCID:0000000162518049)

Publications and source records attributed to Kuhr, T. (ORCID:0000000162518049).

30 records · Page 2

DOE OSTI2023

Measurement of differential distributions of B → D*$\ell\bar{v}_{\ell}$ and implications on | V cb |

We present a measurement of the differential shapes of exclusive B → D*$\ell\bar{v}_{\ell}$ (B = B - , $\bar{B}$ 0 and $\ell$ = e, μ) decays with hadronic tag-side reconstruction for the full 711 fb -1 Belle dataset. We extract the Caprini-Lellouch-Neubert (CLN) and Boyd-Grinstein-Lebed (BGL) form factor parameters and use an external input for the absolute branching fractions to determine the Cabibbo-Kobayashi-Maskawa matrix element and find |V cb | CLN = (40.2 ± 0.9) x 10 -3 and |V cb | BGL = (40.7 ± 1.0) x 10 -3 with the zero-recoil lattice QCD point $\mathcal{F}$(1) = 0.906 ± 0.013. We also perform a study of the impact of beyond zero-recoil lattice QCD calculations on the |V cb | determinations. Additionally, we present the lepton-flavor universality ratio R eμ = $\mathcal{B}$(B → D*e$\bar{v}$ e )/$\mathcal{B}$(B → D*μ$\bar{v}$ μ ) = 0.993 ± 0.023 ± 0.023, the electron and muon forwardbackward asymmetry and their difference ΔA FB = 0.028 ± 0.028 ± 0.008, and the electron and muon D* longitudinal polarization fraction and their difference ΔF$^{D*}_L$ = 0.030 ± 0.025 ± 0.007. The uncertainties quoted correspond to the statistical and systematic uncertainties, respectively.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2023

Study of the lineshape of X ( 3872 ) using B decays to D 0 D ¯ * 0 K

We present a study of the X⁡(3872) lineshape in the decay B →X(3872)⁢K →D 0 $\overline{D}$ *0 ⁢K using a data sample of 772 ×10 6 B$\overline{B}$ pairs collected at the Y⁡(4⁢S) resonance with the Belle detector at the KEKB asymmetric-energy e +⁢ e - collider. The peak near the threshold in the D 0 $\overline{D}$ *0 invariant mass spectrum is fitted using a relativistic Breit-Wigner lineshape. We determine the mass and width parameters to be m BW =3873.7⁢1$^{+0.56}_{-0.50⁢}$(stat) ±0.13⁢(syst) MeV/c 2 and Γ BW =5.2$^{+2.2}_{-1.5}$⁢(stat) ±0.4⁢(syst) MeV, respectively. The branching fraction is found to be $\mathscr{B}$⁡(B + → X⁡(3872)⁢K + ) × $\mathscr{B}$⁡(X⁡(3872) → D 0 $\overline{D}$ *0 ) = (0.9⁢7$^{+0.21}_{-0.18}$⁢(stat) ± 0.10⁢(syst)) ×10 -4 . The signal from B 0 decays is observed for the first time with 5.2σ significance, and the ratio of branching fractions between charged and neutral B decays is measured to be $\mathscr{B}$(B 0 → X⁡(3872)⁢K 0 )/$\mathscr{B}$⁡(B + →X⁡(3872)⁢K + ) =1.34$^{+0.47}_{-0.40}$⁢(stat) $^{+0.10}_{-0.12}$⁢(syst). The peak is also studied using a Flatté lineshape. We determine the lower limit on the D 0 $\overline{D}$ * coupling constant g to be 0.075 at 95% credibility in the parameter region where the ratio of g to the mass difference from the D 0 $\overline{D}$ *0 threshold is equal to -15.11 GeV -1 , as measured by LHCb.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Search for the Lepton Flavor Violating Decays B + → K + τ ± ℓ ∓ ( ℓ = e , μ ) at Belle

We present a search for the lepton flavor violating decays B + → K + ⁢$\tau$ ±⁢ ℓ ∓ , with ℓ = (e,μ), using the full data sample of 772×10 6 B$\overline{B}$ pairs recorded by the Belle detector at the KEKB asymmetric-energy e + ⁢e - collider. We use events in which one B meson is fully reconstructed in a hadronic decay mode. We find no evidence for B ± → K ±⁢ $\tau$⁢ℓ decays and set upper limits on their branching fractions at the 90% confidence level in the (1 - 3) × 10 -5 range. The obtained limits are the world’s best results.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

First observation of B → $\bar{D}$ 1 (→ $\bar{D}$ π + π - ) $\ell$ + ν $\ell$ and measurement of the B → $\bar{D}$ () π$\ell$ + ν $\ell$ and B → $\bar{D}$ () π + π - $\ell$+ ν $\ell$ branching fractions with hadronic tagging at Belle

We report measurements of the ratios of branching fractions for B → $\bar{D}$(*) π$\ell$+ v $\ell$ and B → $\bar{D}$(*)π + π - $\ell$ + v $\ell$ relative to B → $\bar{D}$*$\ell$ + v $\ell$ decays with $\ell$ = e, μ. These results are obtained from a data sample that contains 772 × 10 6 $B\bar{B}$ pairs collected near the $\Upsilon$(4S) resonance with the Belle detector at the KEKB asymmetric energy e + e - collider.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2023

Search for the decay B s 0 → π 0 π 0 at Belle

We report the results of the first search for the decay B$^{0}_{s}$ → π 0 ⁢π 0 using 121.4 fb -1 of data collected at the Y⁡(5⁢S) resonance with the Belle detector at the KEKB asymmetric-energy e + ⁢e - collider. We observe no signal and set a 90% confidence level upper limit of 7.7 ×10 -6 on the B$^{0}_{s}$ → π 0 π 0 decay branching fraction.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Averages of b -hadron, c -hadron, and τ -lepton properties as of 2021

Not Available

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Angular analysis of the low K + K – invariant mass enhancement in B + →K + K – π + decays

We study the decay B + →K + K – π + and investigate the angular distribution of K + K – pairs with invariant mass below 1.1 GeV / c 2 . This region exhibits both a strong enhancement in signal and very large direct CP violation. We construct a coherent sum model for the angular distribution of the S- and P-wave, and report the ratio of their amplitudes, the relative phase and the forward-backward asymmetry. We also report absolute differential branching fractions and direct CP asymmetry for the decay in bins of M K+K– and the differential branching fractions in bins of M K+π– . The results are based on a data sample that contains 772 × 10 6 $B\bar{B}$ pairs collected at the $Υ$(4S) resonance with the Belle detector at the KEKB asymmetric-energy e + e – collider. The result favors the presence of S- and D-waves in low M K+K– region to the detriment of a P-wave.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Search for CP violation and measurement of branching fractions and decay asymmetry parameters for Λ$^+_c$ → Λ h + and Λ$^+_c$ → Σ 0 h + ( h = K, π )

Here, we report a study of Λ$^+_c$ → Λ h + and Λ$^+_c$ → Σ 0 h + ( h = K, π ) decays based on a data sample of 980 fb -1 collected with the Belle detector at the KEKB energy-asymmetric e + e - collider. The first results of direct CP asymmetry in two-body singly Cabibbo-suppressed (SCS) decays of charmed baryons are measured, A$^{dir}_{CP}(Λ^+_{c} → ΛK^{+})$ = +0.021 ± 0.026 ± 0.001 and A$^{dir}_{CP}(Λ^+_{c} → Σ^{0}K^{+})$ = +0.025 ± 0.054 ± 0.004. We also make the most precise measurement of the decay asymmetry parameters (α) for the four modes of interest and search for CP violation via the α-induced CP asymmetry (A$^α_{CP}$ ). We measure A$^α_{CP}$ ($Λ^+_{c} → ΛK^{+}$) = -0.023 ± 0.086 ± 0.071 and A$^α_{CP}$ ($Λ^+_{c} → Σ^{0}K^{+}$) = +0.08 ± 0.35 ± 0.14, which are the first A$^α_{CP}$ results for SCS decays of charmed baryons. We search for Λ -hyperon CP violation in $Λ^+_{c}$ → (Λ, Σ 0 )π + and find A$^α_{CP}$(Λ → pπ - ) = +0.013 ± 0.007 ± 0.011 . This is the first time that hyperon CP violation has been measured via Cabibbo-favored charm decays. No evidence of baryon CP violation is found. We also obtain the most precise branching fractions for two SCS Λ$^+_c$ decays, $\mathscr{B}$($Λ^+_{c} → ΛK^{+}$) = (6.57 ± 0.17 ± 0.11 ± 0.35) x 10 -4 and $\mathscr{B}$($Λ^+_{c} → Σ^{0}K^{+}$) = (3.58 ± 0.19 ±0.06 ±0.19) x 10 -4 . The first uncertainties are statistical and the second systematic, while the third uncertainties come from the uncertainties on the world average branching fractions of $Λ^+_{c}$ → (Λ, Σ 0 )π + .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Measurement of branching fractions of Λ$^+_c$ → p⁢K$^0_S$K$^0_S$ and Λ$^+_c$ → p⁢K$^0_S$⁢η at Belle

We present a study of a singly Cabibbo-suppressed decay Λ$^+_c$ → p⁢K$^0_S$K$^0_S$ and a Cabibbo-favored decay Λ$^+_c$ → p⁢K$^0_S$⁢η based on 980 fb -1 of data collected by the Belle detector, operating at the KEKB energy-asymmetric e + ⁢e - collider. We measure their branching fractions relative to Λ$^+_c$ → p⁢K$^0_S$: $\mathscr{B}$(Λ$^+_c$ → p⁢K$^0_S$K$^0_S$)/$\mathscr{B}$(Λ$^+_c$ → p⁢K$^0_S$) = (1.48 ± 0.08 ± 0.04) × 10 -2 and $\mathscr{B}$(Λ$^+_c$ → p⁢K$^0_S$η)/$\mathscr{B}$(Λ$^+_c$ → p⁢K$^0_S$) = (2.73 ± 0.06 ± 0.13) × 10 -1 . Combining with the world average $\mathscr{B}$(Λ$^+_c$ → p⁢K$^0_S$), we have the absolute branching fractions, $\mathscr{B}$(Λ$^+_c$ → p⁢K$^0_S$K$^0_S$) = (2.35 ± 0.12 ± 0.07 ± 0.12) × 10 -4 and $\mathscr{B}$(Λ$^+_c$ → p⁢K$^0_S$η) = (4.35 ± 0.10 ± 0.20 ± 0.22) × 10 -3 . The first and second uncertainties are statistical and systematic, respectively, while the third ones arise from the uncertainty on $\mathscr{B}$(Λ$^+_c$ → p⁢K$^0_S$). The mode Λ$^+_c$ → p⁢K$^0_S$K$^0_S$ is observed for the first time and has a statistical significance of >10σ. The branching fraction of Λ$^+_c$ → p⁢K$^0_S$η has been measured with a threefold improvement in precision over previous results and is found to be consistent with the world average.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2023

Measurements of branching fractions of Λ$^{+}_{c}$ → Σ + ⁢η and Λ$^{+}_{c}$ → Σ + ⁢η' and asymmetry parameters of Λ$^{+}_{c}$ → Σ + ⁢π 0 , Λ$^{+}_{c}$ → Σ + ⁢η, and Λ$^{+}_{c}$ → Σ + ⁢η'

We report a study of Λ c + → Σ + π 0 , Λ c + → Σ + η , and Λ c + → Σ + η ' using the data sample corresponding to an integrated luminosity of 980 fb - 1 collected with the Belle detector at the KEKB asymmetric-energy e + e - collider. The branching fractions relative to Λ c + → Σ + π 0 are measured as B Λ c + → Σ + η / B Λ c + → Σ + π 0 = 0.25 ± 0.03 ± 0.01 and B Λ c + → Σ + η ' / B Λ c + → Σ + π 0 = 0.33 ± 0.06 ± 0.02 . Using B Λ c + → Σ + π 0 = ( 1.25 ± 0.10 ) % , we obtain B Λ c + → Σ + η = ( 3.14 ± 0.35 ± 0.17 ± 0.25 ) × 10 - 3 and B Λ c + → Σ + η ' = ( 4.16 ± 0.75 ± 0.25 ± 0.33 ) × 10 - 3 . Here the uncertainties are statistical, systematic, and from B Λ c + → Σ + π 0 , respectively. The ratio of the branching fraction of Λ c + → Σ + η ' with respect to that of Λ c + → Σ + η is measured to be B Λ c + → Σ + η ' / B Λ c + → Σ + η = 1.34 ± 0.28 ± 0.08 . We update the asymmetry parameter of Λ c + → Σ + π 0 , α Σ + π 0 = - 0.48 ± 0.02 ± 0.02 , with a considerably improved precision. The asymmetry parameters of Λ c + → Σ + η and Λ c + → Σ + η ' are measured to be α Σ + η = - 0.99 ± 0.03 ± 0.05 and α Σ + η ' = - 0.46 ± 0.06 ± 0.03 for the first time.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Measurement of the branching fractions for Cabibbo-suppressed decays D + → K + K - π + π 0 and D ( s ) + → K + π - π + π 0 at Belle

We present measurements of the branching fractions for the singly Cabibbo-suppressed decays and , and the doubly Cabibbo-suppressed decay , based on of data recorded by the Belle experiment at the KEKB e + ⁢e - collider. We measure these modes relative to the Cabibbo-favored modes D + → K - ⁢π + ⁢π + ⁢π 0 and D$^{+}_{s}$ → K + ⁢K -⁢ π + ⁢π 0 . Our results for the ratios of branching fractions are $\mathscr{B}$⁡(D + →K + ⁢K -⁢ π + ⁢π 0 )/$\mathscr{B}$⁡(D + → K - ⁢π + ⁢π + ⁢π 0 ) =(11.32±0.13±0.26)%, $\mathscr{B}$⁡(D + →K + π - ⁢π + ⁢π 0 )/$\mathscr{B}$(D + →K -⁢ π + ⁢π + ⁢π 0 ) =(1.68±0.11±0.03)%, and $\mathscr{B}$⁡(D$^{+}_{s}$ → K + ⁢π - π + ⁢π 0 )/$\mathscr{B}$⁡(D$^{+}_{s}$ → K + ⁢K - π + π 0 ) =(17.13±0.62±0.51)%, where the uncertainties are statistical and systematic, respectively. The second value corresponds to (5.83 ±0.42) ×tan 4 ⁡θ C , where θ C is the Cabibbo angle; this value is larger than other measured ratios of branching fractions for a doubly Cabibbo-suppressed charm decay to a Cabibbo-favored decay. Multiplying these results by world average values for $\mathscr{B}$⁡(D + → K - ⁢π + ⁢π + ⁢π 0 ) and $\mathscr{B}$⁡(D$^{+}_{s}$ → K + ⁢K - π + π 0 ) yields $\mathscr{B}$( + →K + ⁢K -⁢ π + ⁢π 0 ) = (7.08±0.08±0.16±0.20)×10 -3 , $\mathscr{B}$⁡(D + → K +⁢ π - π + ⁢π 0 ) =(1.05±0.07±0.02±0.03)×10 -3 , and $\mathscr{B}$⁡(D$^{+}_{s}$ → K + ⁢π - π + ⁢π 0 ) =(9.44±0.34±0.28±0.32)×10 -3 , where the third uncertainty is due to the branching fraction of the normalization mode. The first two results are consistent with, but more precise than, the current world averages. The last result is the first measurement of this branching fraction.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2021

Averages of b-hadron, c-hadron, and $$\tau $$-lepton properties as of 2018: Heavy Flavor Averaging Group (HFLAV)

Abstract This paper reports world averages of measurements of b -hadron, c -hadron, and $$\tau $$ 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, $$C\!P$$ C P violation parameters, parameters of semileptonic decays, and Cabibbo–Kobayashi–Maskawa matrix elements.

Amhis, Y. (ORCID:0000000342821512)↗