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Zhang Y. | Zhang L. | Zhang J. | Zhang Wei | Zhang Yu | Zhang Z. P. | Zhang Jun | Zhang Lei | Zhang Rui | Zhang S.

L | L Navaneet K | L Smitha M. | L Srikanth P | L Aashiha Priyadarshni. | L Alex F Estupiñán | L Alex F. Estupiñán | L Altamirano-Dévora | L Arun S | L Berdinskiy V.

M Rajesh Kumar | M Ajith K. | M | M Anand Kumar | M Malaya Kumar Biswal | M Gurunath Reddy | M J. L. Lucio | M Rahul | M Sasikumar | M Shyam Mohan

Search results


Search for the Decay $B_s^0 \rightarrow \eta^\prime \eta$

Belle Collaboration , Abdesselam A., Adachi I., Adamczyk K., Ahn J. K., Aihara H., Said S. Al, Arinstein K., Arita Y., Asner D. M.
13 Sep 2020 hep-ex arxiv.org/abs/2009.06052

In the Standard Model (SM) charmless hadronic decays $B_s^0 \rightarrow \eta^\prime \eta$ proceed via tree-level $b\to u$ and penguin $b\to s$ transitions. Penguin transitions are sensitive to Beyond-the-Standard-Model (BSM) physics scenarios and could affect the branching fractions and {\it CP} asymmetries in such decays. Once branching fractions for two-body decays $B_s \to \eta\eta, \eta\eta^{\prime}, \eta^{\prime}\eta^{\prime} $ are measured, and the theoretical uncertainties are reduced, it would be possible to extract {\it CP} violating parameters from the data using the formalism based on SU(3)/U(3) symmetry. To achieve this goal, at least four of these six branching fractions need to be measured. Only the branching fraction for $B_s^0 \to \eta^{\prime}\eta^{\prime}$ has been measured so far.

Measurement of two-particle correlations in hadronic $e^{+}e^{-}$ collisions at Belle

Belle Collaboration , Abdesselam A., Adachi I., Adamczyk K., Ahn J. K., Aihara H., Said S. Al, Arinstein K., Arita Y., Asner D. M.
10 Aug 2020 hep-ex arxiv.org/abs/2008.04187

The enhancement of charged-particle pairs with large pseudorapidity difference and small azimuthal angle difference, often referred to as the ``ridge signal'', is a phenomenon widely observed in high multiplicity proton-proton, proton-ion and deutron-ion collisions, which is not yet fully understood. In heavy-ion collisions, the hydrodynamic expansion of the Quark-Gluon Plasma is one of the possible explanations of the origin of the ridge signal. Measurements in the $e^+e^-$ collision system, without the complexities introduced by hadron structure in the initial state, can serve as a complementary probe to examine the formation of a ridge signal. The first measurement of two-particle angular correlation functions in high multiplicity $e^+e^-$ collisions at $\sqrt{s}=10.52$ GeV is reported. The hadronic $e^+e^-$ annihilation data collected by the Belle detector at KEKB are used in this study. Two-particle angular correlation functions are measured over the full azimuth and large pseudorapidity intervals which are defined by either the electron beam axis or the event thrust as a function of charged particle multiplicity. The measurement in the event thrust analysis, with mostly outgoing quark pairs determining the reference axis, is sensitive to the region of additional soft gluon emissions. No significant ridge signal is observed with either coordinates analyses. Near side jet correlations appear to be absent in the thrust axis analysis. The measurements are compared to predictions from various event generators and expected to provide new constraints to the phenomenological models in the low energy regime.

Measurement of {\boldmath $J/\psi\to\Xi(1530)^{-}\bar\Xi^{+}$} and evidence for the radiative decay {\boldmath $\Xi(1530)^{-}\to\gamma\Xi^-$}

BESIII Collaboration , Ablikim M., Achasov M. N., Adlarson P., Ahmed S., Albrecht M., Alekseev M., Amoroso A., An F. F., An Q.
15 Nov 2019 hep-ex arxiv.org/abs/1911.06669

The SU(3)-flavor violating decay $J/\psi\to\Xi(1530)^{-}\bar\Xi^{+}+c.c.$ is studied using $(1310.6\pm7.0)\times 10^{6} ~J/\psi$ events collected with the BESIII detector at BEPCII and the branching fraction is measured to be ${\cal{B}}(J/\psi\to\Xi(1530)^{-}\bar\Xi^{+}+c.c.)=(3.17\pm0.02_{\rm stat.}\pm0.08_{\rm syst.})\times10^{-4}$. This is consistent with previous measurements with an improved precision. The angular parameter for this decay is measured for the first time and is found to be $\alpha=-0.21\pm0.04_{\rm stat.}\pm0.06_{\rm syst.}$. In addition, we report evidence for the radiative decay $\Xi(1530)^{-}\to\gamma\Xi^- $ with a significance of 3.9$\sigma$, including the systematic uncertainties. The 90\% confidence level upper limit on the branching fraction is determined to be $\mathcal{B}(\Xi(1530)^{-}\to\gamma\Xi^- )\leq3.7$\%.

Experimental determination of the isospin of $\Lambda_c(2765)^+/\Sigma_c(2765)^+$

The Belle Collaboration , Abdesselam A., Adachi I., Adamczyk K., Ahn J. K., Aihara H., Said S. Al, Arinstein K., Arita Y., Asner D. M.
17 Aug 2019 hep-ex arxiv.org/abs/1908.06235

We report an experimental determination of the isospin of $\Lambda_c(2765)^+/\Sigma_c(2765)^+$ using 980 fb$^{-1}$ data in the $e^+e^-$ annihilation around $\sqrt{s} = 10.6$ GeV collected by the Belle detector located at the KEKB collider. The isospin partners are searched for in the $\Sigma_c(2455)^{++/0} \pi^{0}$ channels, and no evidence was obtained. Thus the isospin is determined to be zero, and the particle is established to be a $\Lambda_c$.

Measurement of $\mathcal{R}(D)$ and $\mathcal{R}(D^{\ast})$ with a semileptonic tagging method

The Belle Collaboration , Abdesselam A., Adachi I., Adamczyk K., Aihara H., Said S. Al, Arinstein K., Arita Y., Asner D. M., Aso T.
18 Apr 2019 hep-ex arxiv.org/abs/1904.08794

We report a measurement of the ratios of branching fractions $\mathcal{R}(D) = {\cal B}(\bar{B} \to D \tau^- \bar{\nu}{\tau})/{\cal B}(\bar{B} \to D \ell^- \bar{\nu}{\ell})$ and $\mathcal{R}(D^{\ast}) = {\cal B}(\bar{B} \to D^* \tau^- \bar{\nu}{\tau})/{\cal B}(\bar{B} \to D^* \ell^- \bar{\nu}{\ell})$, where $\ell$ denotes an electron or a muon. The results are based on a data sample containing $772\times10^6$ $B\bar{B}$ events recorded at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB $e^+ e^-$ collider. The analysis utilizes a method where the tag-side $B$ meson is reconstructed in a semileptonic decay mode, and the signal-side $\tau$ is reconstructed in a purely leptonic decay. The measured values are $\mathcal{R}(D)= 0.307 \pm 0.037 \pm 0.016$ and $\mathcal{R}(D^{\ast})= 0.283 \pm 0.018 \pm 0.014$, where the first uncertainties are statistical and the second are systematic. These results are in agreement with the Standard Model predictions within $0.2$ and $1.1$ standard deviations, respectively, while their combination agrees with the Standard Model predictions within $1.2$ standard deviations.

Measurement of the $D^{\ast-}$ polarization in the decay $B^0 \to D^{\ast -}\tau^+\nu_{\tau}$

Belle Collaboration , Abdesselam A., Adachi I., Adamczyk K., Ahn J. K., Aihara H., Said S. Al, Arinstein K., Arita Y., Asner D. M.
07 Mar 2019 hep-ex arxiv.org/abs/1903.03102

We report the first measurement of the $D^{\ast -}$ meson polarization in the decay $B^0 \to D^{*-} \tau^+\nu_{\tau}$ using the full data sample of 772$\times 10^6$ $B\bar{B}$ pairs recorded with the Belle detector at the KEKB electron-positron collider. Our result, $F_L^{D^\ast} = 0.60 \pm 0.08 ({\rm stat}) \pm 0.04 ({\rm sys})$, where $F_L^{D^\ast}$ denotes the $D^{\ast-}$ meson longitudinal polarization fraction, agrees within about $1.7$ standard deviations of the standard model prediction.

Study of charmless decays $B^{\pm} \to K^{0}_{S} K^{0}_{S} h^{\pm}$ ($h=K,\pi$) at Belle

The Belle Collaboration , Abdesselam A., Adachi I., Adamczyk K., Ahn J. K., Aihara H., Said S. Al, Arinstein K., Arita Y., Asner D. M.
01 Aug 2018 hep-ex arxiv.org/abs/1808.00174

We report a search for charmless hadronic decays of charged $B$ mesons to the final states $K^{0}{S} K^{0}{S} K^{\pm}$ and $K^{0}{S} K^{0}{S} \pi^{\pm}$ . The results are based on a $711 {fb}^{-1}$ data sample that contains $772 \times 10^6$ $B \bar{B}$ pairs, and was collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. For $B^{\pm} \to K^{0}{S} K^{0}{S} K^{\pm}$ decays, the measured branching fraction and direct $CP$ asymmetry are $[10.64\pm0.49(stat)\pm 0.44(syst)]\times10^{-6}$ and [$-0.6\pm3.9(stat)\pm 3.4(syst)$] %, respectively. In the absence of a statistically significant signal for $B^{\pm}\to K^{0}{S} K^{0}{S} \pi^{\pm}$, we set the 90 % confidence-level upper limit on its branching fraction at $1.14 \times 10^{-6}$.

Measurements of branching fraction and $CP$ asymmetry of the $\bar{B}^{0}(B^{0})\to K^{0}_{S}K^{\mp}\pi^{\pm}$ decay at Belle

Abdesselam A., Adachi I., Adamczyk K., Ahn J. K., Aihara H., Said S. Al, Arinstein K., Arita Y., Asner D. M., Atmacan H.
18 Jul 2018 hep-ex arxiv.org/abs/1807.06782

We report the measurement of the branching fraction and $CP$ asymmetry for the $\bar{B}^{0}(B^{0})\to K^{0}{S}K^{\mp}\pi^{\pm}$ decay. The analysis is performed on a data sample of 711 $\rm{fb}^{-1}$ collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. We obtain a branching fraction of $(3.60\pm0.33\pm0.15)\times10^{-6}$ and an $\mathcal{A}{CP}$ of $(-8.5\pm8.9\pm0.2)\%$, where the first uncertainties are statistical and the second are systematic. Hints of peaking structures are also observed in the differential branching fraction as functions of Dalitz variables.

Optimal Orientations of Quartz Crystals for Bulk Acoustic Wave Resonators with the Consideration of Thermal Properties

Wang J., Zhang L. M., Wang S. Y., Xie L. T., Huang B., Ma T. F., Du J. K., Chao M. C., Shen S., Wu R. X.
26 Dec 2017 cond-mat.mtrl-sci arxiv.org/abs/1712.09187

Piezoelectric crystals are widely used for acoustic wave resonators of different functioning modes and types including BAW and SAW. It is well-known that only some special orientations of crystals will exhibit desirable properties such as mode couplings, thermal sensitivity, acceleration sensitivity, and others that are important in design and applications of resonators. With extensive studies on physical properties in last decades and increasing industrial needs of novel products, it is necessary to comb the known knowledge of quartz crystal material for novel orientations and better products as agendas in the industry. With known material properties like elastic, piezoelectric, dielectric, and thermal constants, we can establish the relationships between vibrations and bias fields such as temperature to ensure a resonator immunizing from excessive response to changes causing significant degradation of resonator properties and performances. Since the theoretical framework of wave propagation in piezoelectric solids is known, we need to use the existing data and results for the validation of current orientations in actual products. The agreement will give us needed confidence of the theory and analytical procedures. Through rotations, we calculated physical properties as functions of angles and bias fields, enabling the calculation of resonator properties for the identification of optimal cuts. Such a procedure can also be applied to similar crystals for a careful examination of possible orientations to maximize the potential use of materials in acoustic wave resonators.

Measurement of the tau Michel parameters $\bar{\eta}$ and $\xi\kappa$ in the radiative leptonic decay $\tau^- \rightarrow \ell^- \nu_{\tau} \bar{\nu}_{\ell}\gamma$

The Belle Collaboration , Shimizu N., Aihara H., Epifanov D., Abdesselam A., Adachi I., Adamczyk K., Said S. Al, Arinstein K., Arita Y.
26 Sep 2017 hep-ex arxiv.org/abs/1709.08833

We present a measurement of the Michel parameters of the $\tau$ lepton, $\bar{\eta}$ and $\xi\kappa$, in the radiative leptonic decay $\tau^- \rightarrow \ell^- \nu_{\tau} \bar{\nu}{\ell} \gamma$ using 711~f$\mathrm{b}^{-1}$ of collision data collected with the Belle detector at the KEKB $e^+e^-$ collider. The Michel parameters are measured in an unbinned maximum likelihood fit to the kinematic distribution of $e^+e^-\rightarrow\tau^+\tau^-\rightarrow (\pi^+\pi^0 \bar{\nu}\tau)(\ell^-\nu_{\tau}\bar{\nu}_{\ell}\gamma)$ $(\ell=e$ or $\mu)$. The measured values of the Michel parameters are $\bar{\eta} = -1.3 \pm 1.5 \pm 0.8$ and $\xi\kappa = 0.5 \pm 0.4 \pm 0.2$, where the first error is statistical and the second is systematic. This is the first measurement of these parameters. These results are consistent with the Standard Model predictions within their uncertainties and constrain the coupling constants of the generalized weak interaction.