The PADME experiment at the LNF Beam Test Facility searches for dark photons produced in the annihilation of positrons with the electrons of a fix target. The strategy is to look for the reaction ...\(e^{+}+e^{-}\rightarrow \gamma+A'\), where \(A'\) is the dark photon, which cannot be observed directly or via its decay products. The electromagnetic calorimeter plays a key role in the experiment by measuring the energy and position of the final-state \(\gamma\). The missing four-momentum carried away by the \(A'\) can be evaluated from this information and the particle mass inferred. This paper presents the design, construction, and calibration of the PADME's electromagnetic calorimeter. The results achieved in terms of equalisation, detection efficiency and energy resolution during the first phase of the experiment demonstrate the effectiveness of the various tools used to improve the calorimeter performance with respect to earlier prototypes.
We report on the first Belle II measurement of the branching fraction
($\mathcal{B}$) and longitudinal polarization fraction ($f_L$) of $B^+\to
\rho^+\rho^0$ decays. We reconstruct $B^+\to \rho^+(\to ...\pi^+\pi^0(\to
\gamma\gamma))\rho^0(\to \pi^+\pi^-)$ decays in a sample of SuperKEKB
electron-positron collisions collected by the Belle II experiment in 2019 and
2020 at the $\Upsilon$(4S) resonance and corresponding to $62.8$ fb$^{-1}$ of
integrated luminosity. We fit the distributions of the difference between
expected and observed $B$ candidate energy, continuum-suppression variable,
dipion masses, and angular distributions of the resulting samples, to determine
a signal yield of $104\pm16$ events. The signal yields are corrected for
efficiencies determined from simulation and control data samples to obtain
$\mathcal{B}(B^+ \to \rho^+\rho^0) = 20.6 \pm 3.2(\rm stat) \pm 4.0(\rm
syst)\times 10^{-6}$, and $f_L(B^+ \to \rho^+\rho^0) = 0.936
^{+0.049}_{-0.041}(\rm stat)\pm 0.021(\rm syst)$. This first Belle II $B^+ \to
\rho^+\rho^0$ angular analysis yields results compatible with previous
determinations, and indicates Belle II performance superior to early Belle
results.
We report on measurements of branching fractions ($\mathcal{B}$) and
CP-violating charge asymmetries ($\mathcal{A}_{\rm CP}$) of multibody charmless
$B$ decays reconstructed by the Belle II ...experiment at the SuperKEKB
electron-positron collider. We use a sample of collisions collected in 2019 and
2020 at the $\Upsilon(4S)$ resonance and corresponding to $62.8$ fb$^{-1}$ of
integrated luminosity. We use simulation to determine optimized event
selections. The $\Delta E$ and $M_{\rm bc}$ distributions of the resulting
samples are fit to determine signal yields of approximately 690, 840, and 380
decays for the channels $B^+ \to K^+K^-K^+$, $B^+ \to K^+\pi^-\pi^+$, and $B^0
\to K^+\pi^-\pi^0$, respectively. These yields are corrected for efficiencies
determined from simulation and control data samples to obtain $\mathcal{B}(B^+
\to K^+K^-K^+) = 35.8 \pm 1.6(\rm stat) \pm 1.4 (\rm syst)\times 10^{-6}$,
$\mathcal{B}(B^+ \to K^+\pi^-\pi^+) = 67.0 \pm 3.3 (\rm stat)\pm 2.3 (\rm
syst)\times 10^{-6}$, $\mathcal{B}(B^0 \to K^+\pi^-\pi^0) = 38.1 \pm 3.5 (\rm
stat)\pm 3.9 (\rm syst)\times 10^{-6}$, $\mathcal{A}_{\rm CP}(B^+ \to
K^+K^-K^+) = -0.103 \pm 0.042(\rm stat) \pm 0.020 (\rm syst)$,
$\mathcal{A}_{\rm CP}(B^+ \to K^+\pi^-\pi^+) = -0.010 \pm 0.050 (\rm stat)\pm
0.021(\rm syst)$, and $\mathcal{A}_{\rm CP}(B^0 \to K^+\pi^-\pi^0) = 0.207 \pm
0.088 (\rm stat)\pm 0.011(\rm syst)$. Results are consistent with previous
measurements and demonstrate detector performance comparable with the best
Belle results.
Since the 1990s Grid Computing has emerged as a paradigm for accessing and managing distributed, heterogeneous and geographically spread resources, promising that we will be able to access computer ...power as easily as we can access the electric power grid. Later on, Cloud Computing brought the promise of providing easy and inexpensive access to remote hardware and storage resources. Exploiting pay-per-use models and virtualization for resource provisioning, cloud computing has been rapidly accepted and used by researchers, scientists and industries.In this volume, contributions from internationally recognized experts describe the latest findings on challenging topics related to grid and cloud database management. By exploring current and future developments, they provide a thorough understanding of the principles and techniques involved in these fields. The presented topics are well balanced and complementary, and they range from well-known research projects and real case studies to standards and specifications, and non-functional aspects such as security, performance and scalability. Following an initial introduction by the editors, the contributions are organized into four sections: Open Standards and Specifications, Research Efforts in Grid Database Management, Cloud Data Management, and Scientific Case Studies.With this presentation, the book serves mostly researchers and graduate students, both as an introduction to and as a technical reference for grid and cloud database management. The detailed descriptions of research prototypes dealing with spatiotemporal or genomic data will also be useful for application engineers in these fields.
We report the first reconstruction of the $B^{0} \to \pi^{0} \pi^{0}$ decay
mode at Belle II using samples of 2019 and 2020 data that correspond to 62.8
fb$^{-1}$ of integrated luminosity. We find ...$14.0^{+6.8}_{-5.6}$ signal decays,
corresponding to a significance of 3.4 standard deviations and determine a
branching ratio of $\mathcal{B}(B^{0} \rightarrow \pi^{0} \pi^{0}) =
0.98^{+0.48}_{-0.39} \pm 0.27 \times 10^{-6}$. The results agree with
previous determinations and contribute important information to an early
assessment of detector performance and Belle II's potential for future
determinations of $\alpha/\phi_2$ using $B \rightarrow \pi \pi$ modes.
We present preliminary results on the reconstruction of the $B^0\to J\mskip
1mu / \psi\mskip 2mu K^0_{\scriptscriptstyle L}$ decay, where $J\mskip 1mu /
\psi\mskip 2mu\to\mu^+\mu^-$ or $e^+e^-$. ...Using a dataset corresponding to a
luminosity of $62.8\pm0.6\mbox{fb}^{-1}$ collected by the Belle II experiment
at the SuperKEKB asymmetric energy $e^+e^-$ collider, we measure a total of
$267\pm21$ candidates with $J\mskip 1mu / \psi\mskip 2mu\to\mu^+\mu^-$ and
$226\pm20$ with with $J\mskip 1mu / \psi\mskip 2mu\to e^+e^-$. The quoted
errors are statistical only.
We report updated measurements of branching fractions ($\mathcal{B}$) and
CP-violating charge asymmetries ($\mathcal{A_{\rm CP}}$) for charmless $B$
decays at Belle II, which operates on or near the ...$\Upsilon$(4S) resonance at
the SuperKEKB asymmetric energy $e^{+}e^{-}$ collider. We use samples of 2019
and 2020 data corresponding to 62.8 fb$^{-1}$ of integrated luminosity. The
samples are analysed using two-dimensional fits in $\Delta E$ and $M_{\it bc}$
to determine signal yields of approximately 568, 103, and 115 decays for the
channels $B^0 \to K^+\pi^-$, $B^+ \to K_{\rm S}^0\pi^+$, and $B^0 \to
\pi^+\pi^-$, respectively. Signal yields are corrected for efficiencies
determined from simulation and control data samples to obtain branching
fractions and CP-violating asymmetries for flavour-specific channels. The
results are compatible with known determinations and contribute important
information to an early assessment of Belle II detector performance.
We present the first measurement of the time-integrated mixing probability
$\chi_d$ using Belle II data collected at a center-of-mass (CM) energy of 10.58
GeV, corresponding to the mass of the ...$\Upsilon$(4S) resonance, with an
integrated luminosity of $34.6 {\rm fb}^{-1}$ at the SuperKEKB $e^+ e^-$
collider. We reconstruct pairs of B mesons both of which decay to semileptonic
final states. Using a novel methodology, we measure $\chi_d = 0.187 \pm 0.010
\text{ (stat.)} \pm 0.019 \text{ (syst.)}$, which is compatible with existing
indirect and direct determinations.
We report measurements of branching fractions ($\mathcal B$) and direct ${\it
CP}$-violating asymmetries ($\mathcal A_{\it CP}$) for the decays $B^+\to
K^+\pi^0$ and $B^+ \to \pi^+\pi^0$ ...reconstructed with the Belle II detector in
a sample of asymmetric-energy electron-positron collisions at the
$\Upsilon(4S)$ resonance corresponding to 62.8 $\text{fb}^{-1}$ of integrated
luminosity. The results are $\mathcal{B}(B^+ \to K^+\pi^0) = 11.9
^{+1.1}_{-1.0} (\rm stat)\pm 1.6(\rm syst)\times 10^{-6}$, $\mathcal{B}(B^+
\to \pi^+\pi^0) = 5.5 ^{+1.0}_{-0.9} (\rm stat)\pm 0.7(\rm syst)\times
10^{-6}$, $\mathcal A_{\it CP}(B^+ \to K^+\pi^0) = -0.09 \pm 0.09 (\rm stat)\pm
0.03(\rm syst)$, and $\mathcal A_{\it CP}(B^+ \to \pi^+\pi^0) = -0.04 \pm 0.17
(\rm stat)\pm 0.06(\rm syst)$. The results are consistent with previous
measurements and show a detector performance comparable with early Belle
performance.
