Search results for "signal processing"
showing 10 items of 2451 documents
The track finding algorithm of the Belle II vertex detectors
2017
The Belle II experiment is a high energy multi purpose particle detector operated at the asymmetric e + e − - collider SuperKEKB in Tsukuba (Japan). In this work we describe the algorithm performing the pattern recognition for inner tracking detector which consists of two layers of pixel detectors and four layers of double sided silicon strip detectors arranged around the interaction region. The track finding algorithm will be used both during the High Level Trigger on-line track reconstruction and during the off-line full reconstruction. It must provide good efficiency down to momenta as low as 50 MeV/c where material effects are sizeable even in an extremely thin detector as the VXD. In a…
B meson decay constants f B c $$ {f}_{B_c} $$ , f B s $$ {f}_{B_s} $$ and f B from QCD sum rules
2014
Finite energy QCD sum rules with Legendre polynomial integration kernels are used to determine the heavy meson decay constant f B c $$ {f}_{B_c} $$ , and revisit f B and f B s $$ {f}_{B_s} $$ . Results exhibit excellent stability in a wide range of values of the integration radius in the complex squared energy plane, and of the order of the Legendre polynomial. Results are f B c $$ {f}_{B_c} $$ = 528 ± 19 MeV, f B = 186 ± 14 MeV, and f B s $$ {f}_{B_s} $$ = 222 ± 12 MeV.
Measurement of thee+e−→bb¯Cross Section betweens=10.54and 11.20 GeV
2009
We report e;{+}e;{-}-->bb[over ] cross section measurements by the BABAR experiment performed during an energy scan in the range of 10.54 to 11.20 GeV at the SLAC PEP-II e;{+}e;{-} collider. A total relative error of about 5% is reached in more than 300 center-of-mass energy steps, separated by about 5 MeV. These measurements can be used to derive precise information on the parameters of the Upsilon(10860) and Upsilon(11020) resonances. In particular we show that their widths may be smaller than previously measured.
Study of the process e+e−→ϕη at center-of-mass energies between 2.00 and 3.08 GeV
2021
We study the process e^+e^− → π^+π^−ηγ, where the photon is radiated from the initial state. About 8000 fully reconstructed events of this process are selected from the BABAR data sample with an integrated luminosity of 469 fb^(-1). Using the π^+π^−η invariant mass spectrum, we measure the e^+e^− → π^+π^−η cross section in the e^+e^− center-of-mass energy range from 1.15 to 3.5 GeV. The cross section is well described by the Vector-Meson dominance model with four ρ-like states. We observe 49±9 events of the J/ψ decay to π^+π^−η and measure the product Γ_(J/Ψ → e^+e^−)B_(J/Ψ → π^+π^−η) = 2.34 ± 0.43_(stat) ± 0.16_(syst) eV.
Unexplained Excess of Electronlike Events from a 1-GeV Neutrino Beam
2009
The MiniBooNE Collaboration observes unexplained electronlike events in the reconstructed neutrino energy range from 200 to 475 MeV. With 6.46 x 10(20) protons on target, 544 electronlike events are observed in this energy range, compared to an expectation of 415.2 +/- 43.4 events, corresponding to an excess of 128.8 +/- 20.4 +/- 38.3 events. The shape of the excess in several kinematic variables is consistent with being due to either nu(e) and (nu) over bar (e) charged-current scattering or nu(mu) neutral-current scattering with a photon in the final state. No significant excess of events is observed in the reconstructed neutrino energy range from 475 to 1250 MeV, where 408 events are obse…
Forward tracking at the nexte+e−collider. Part I. The physics case
2009
n a series of notes we explore the detector requirements of the forward tracking region for a future e(+)e(-) collider with a center-of-mass energy in the range from 500 GeV to 3 TeV. In this first part we investigate the relevance of the forward region for a range of physics processes that are likely to be relevant in such a machine. We find that many examples can be found where excellent performance of the forward detector system may lead to a considerable increase of the physics output of the experiment. A particularly clear physics case can be made for the reconstruction of electrons at small polar angle.
Soft-photon radiative corrections to the e−p→e−pl−l+ process
2021
We calculate the leading-order QED radiative corrections to the process ${e}^{\ensuremath{-}}p\ensuremath{\rightarrow}{e}^{\ensuremath{-}}p{l}^{\ensuremath{-}}{l}^{+}$ in the soft-photon approximation, in two different energy regimes which are of relevance to extract nucleon structure information. In the low-energy region, this process is studied to better constrain the hadronic corrections to precision muonic hydrogen spectroscopy. In the high-energy region, the beam-spin asymmetry for double-virtual Compton scattering allows us to directly access the generalized parton distributions. We find that the soft-photon radiative corrections have a large impact on the cross sections and are there…
Single-energy partial wave analysis for pion photoproduction with fixed-t analyticity
2021
Experimental data for pion photoproduction including differential cross sections and various polarization observables from four reaction channels, $\gamma p \to \pi^0 p$, $\gamma p \to \pi^+n$, $\gamma n \to \pi^- p$ and $\gamma n \to \pi^0 n$ from threshold up to $W=2.2$ GeV have been used in order to perform a single-energy partial wave analysis with minimal model dependence by imposing constraints from unitarity and fixed-$t$ analyticity in an iterative procedure. Reaction models were only used as starting point in the very first iteration. We demonstrate that with this procedure partial wave amplitudes can be obtained which show only a minimal dependence on the initial model assumptions…
Measurement of the Beam-Helicity Asymmetry in thep(e→,e′p)π0Reaction at the Energy of theΔ(1232)Resonance
2002
In a p((e) over right arrow, e' p)pi(0) out-of-plane coincidence experiment at the three-spectrometer setup of the Mainz Microtron MAMI, the beam-helicity asymmetry has been precisely measured around the energy of the Delta(1232) resonance and Q(2) = 0.2(GeV/c)(2). The results are in disagreement with three up-to-date model calculations. This is interpreted as a lack of understanding of the nonresonant background, which in dynamical models is related to the pion cloud.
Interplay of order-disorder phenomena and diffusion in rigid binary alloys in the presence of vacancies: Monte Carlo simulations
2006
Transport phenomena are studied for a binary $(AB)$ alloy on a rigid square lattice with nearest-neighbor attraction between unlike particles, assuming a small concentration ${c}_{v}$ of vacancies $V$ being present, to which $A$ $(B)$ particles can jump with rates ${\ensuremath{\Gamma}}_{A}$ $({\ensuremath{\Gamma}}_{B})$ in the case where the nearest-neighbor attractive energy ${ϵ}_{AB}$ is negligible in comparison with the thermal energy ${k}_{B}T$ in the system. This model exhibits a continuous order-disorder transition for concentrations ${c}_{A},{c}_{B}=1\ensuremath{-}{c}_{A}\ensuremath{-}{c}_{V}$ in the range ${c}_{A,1}^{\mathit{crit}}\ensuremath{\leqslant}{c}_{A}\ensuremath{\leqslant}…