A measurement of the photon polarization in radiative penguin
B
decays provides a test of the Standard Model and a probe for New Physics, that can lead to a deviation from the Standard Model ...prediction of left-handed photons in
b
→
s
γ
. We propose a new method to measure the photon polarization using the baryonic decay
B
-
→
Λ
p
¯
γ
. The
P
-violating
Λ
-hyperon decay allows a measurement of the
Λ
helicity to be performed, which can be uniquely related to the photon polarization in a model-independent way. The
B
-
→
Λ
p
¯
γ
decay was recently measured to have a large branching fraction providing a possibility to get meaningful results with the data already available at LHC and B-factory experiments. An increase of the
B
-meson sample at high luminosity LHC experiments and Belle II should provide a really stringent test by using this method already in the near future.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In a previous paper we suggested an explanation for the peak designated as Z(4430)+ in the ψ′π+ mass spectrum, observed by Belle in B¯→ψ′π+K decays, as an effect of D¯⁎0D+→ψ′π+ rescattering in the ...decays B¯→Ds′−D, where the Ds′− is an as-yet unobserved radial excitation of the pseudoscalar ground state Ds−-meson. In this paper, we demonstrate that this hypothesis provides an explanation of the double Z+-like peaking structures, which were studied by LHCb with much higher statistics. While according to our hypothesis, the origin of the peaking structures is due to the kinematical reflection of conventional resonances in the unobserved intermediate state, the amplitude of the Z(4430)+ peak carries a Breit–Wigner-like complex phase, arising from the intermediate Ds′− resonance. Thus, our hypothesis is entirely consistent with the recent LHCb measurement of the resonant-like amplitude behavior of the Z(4430)+. We perform a toy fit to the LHCb data, which illustrates that our approach is also consistent with all the observed structure in the LHCb M(ψ′π+) spectrum. We suggest a critical test of our hypothesis that can be performed experimentally.
We have studied a system based on scintillator counters with WLS fiber light collection and SiPM readout for the Belle II experiment. We have identified a few simple improvements in the strip ...production technology which allow significant increases in the light collection efficiency, thus increasing the efficiency and robustness of the entire detector. The new system should work efficiently at background rates and radiation doses ∼100 times larger than those observed for the Belle experiment. As demonstrated by many tests, the system has sufficient robustness to operate well in a strong magnetic field and high radiation and interaction environment with no significant degradation anticipated after many years of data taking. While this system was designed for a particular experiment, namely Belle II, our study can be applied to the construction of muon systems in many experiments.
Experiments at the Super Charm-Tau factory Achasov, Mikhail N.; Blinov, Vladimir E.; Bobrov, Alexander V. ...
Physics Uspekhi,
01/2024, Letnik:
67, Številka:
1
Journal Article
We review numerous results from the B-Factories, obtained last decade. They provide currently strong constraints on New Physics extensions beyond the Standard Model. We discuss the physics program at ...Super B-factory, a next generation asymmetric collider with the luminosity almost two orders of magnitude higher than those achieved at the existing colliders, and its capability in cooperation with LHC of new insights into New Physics phenomena.
Data on open-charm channels collected by the Belle Collaboration are analyzed simultaneously using a unitary approach based on a coupled-channel model in a wide energy range √s = 3.7–4.7 GeV. The ...resulting fit provides a remarkably good overall description of the line shapes in all studied channels. The parameters of five vector charmonium resonances are extracted from the fit.
In this paper we discuss a possible interpretation of the charged charmonium-like states observed in B decays as a rescattering effect. This approach allows to avoid introduction of exotic hadrons ...into the theory, while explains the unusual peaking structures 4observed recently in three body B decays. In particular, the peaks in the ψ(2S)π+ mass spectrum are ascribed to the rescattering process with kinematics governed by the presence of conventional radial excitations, the Ds(*)' resonances, in the hidden intermediate state. Our predictions are compared to the LHCb results.
SuperKEKB, the next generation B factory, has been constructed in Japan as an upgrade of KEKB. This brand new e+ e- collider is expected to deliver a very large data set for the Belle II experiment, ...which will be 50 times larger than the previous Belle sample. Both the triggered physics event rate and the background event rate will be increased by at least 10 times than the previous ones, and will create a challenging data taking environment for the Belle II detector. The software system of the Belle II experiment is designed to execute this ambitious plan. A full detector simulation library, which is a part of the Belle II software system, is created based on Geant4 and has been tested thoroughly. Recently the library has been upgraded with Geant4 version 10.1. The library is behaving as expected and it is utilized actively in producing Monte Carlo data sets for various studies. In this paper, we will explain the structure of the simulation library and the various interfaces to other packages including geometry and beam background simulation.
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