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ACHILLES-GENIE Interface for Neutrino Simulations, ADRIANO2 Tile Prototype for High-Granularity Dual-Readout Calorimetry
ICARUS (Imaging Cosmic And Rare Underground Signals) is a liquid argon time projection chamber (LArTPC) detector that pursues the sterile neutrino, which relies on accurate simulations of neutrino-argon interactions. REDTOP (Rare Eta Decays To Observe new Physics) is a proposed low-energy, high-intensity meson factory designed to explore rare $\eta$/$\eta'$ meson decays and probe physics beyond the Standard Model. As a next-generation experiment, this requires both accurate simulations and innovative detector technologies. This project contributes to both ICARUS, from a simulation perspective, and REDTOP, from both a simulation and detection perspective, through the event generation of lepton-nucleon interactions and the physical enhancement of the calorimeter technology within the REDTOP detector. We developed an interface between ACHILLES (A CHIcago Land Lepton Event Simulator), a theory-driven lepton-level event generator, and GENIE, a robust event generator framework used for neutrino physics. By incorporating the precise theoretical cross-section calculations of ACHILLES into the experimental realism of GENIE, the interface allows for improved accuracy of neutrino-nucleon simulations, which can be adapted for the proton beam specifications of the REDTOP meson factory as well as for the ICARUS experiment. In parallel, we developed an improved prototype for the ADRIANO2 (A Dual Readout Integrally Active Non-segmented Option) dual-readout calorimeter tiles for the REDTOP detector. To improve the efficiency of the lead-glass tiles trapping Cherenkov light for energy reconstruction and particle identification, we optimized the application of a highly reflective coating. Through viscosity and thickness control, masking, and a custom spray technique, we refined the coating process to reduce surface defects and improve light yield. Together, these efforts strengthen the ICARUS neutrino program and REDTOP's capability of detecting rare decay events.
Enhancing ICARUS and REDTOP Software and Hardware: Event Generator Interface Development and Calorimeter Tile Prototype
ICARUS (Imaging Cosmic And Rare Underground Signals) is a liquid argon time projection chamber (LArTPC) detector that pursues the sterile neutrino, which relies on accurate simulations of neutrino-argon interactions. REDTOP (Rare Eta Decays To Observe new Physics) is a proposed low-energy, high-intensity meson factory designed to explore rare $\eta$/$\eta'$ meson decays and probe physics beyond the Standard Model. As a next-generation experiment, this requires both accurate simulations and innovative detector technologies. This project contributes to both ICARUS, from a simulation perspective, and REDTOP, from both a simulation and detection perspective, through the event generation of lepton-nucleon interactions and the physical enhancement of the calorimeter technology within the REDTOP detector. We developed an interface between ACHILLES (A CHIcago Land Lepton Event Simulator), a theory-driven lepton-level event generator, and GENIE, a robust event generator framework used for neutrino physics. By incorporating the precise theoretical cross-section calculations of ACHILLES into the experimental realism of GENIE, the interface allows for improved accuracy of neutrino-nucleon simulations, which can be adapted for the proton beam specifications of the REDTOP meson factory as well as for the ICARUS experiment. In parallel, we developed an improved prototype for the ADRIANO2 (A Dual Readout Integrally Active Non-segmented Option) dual-readout calorimeter tiles for the REDTOP detector. To improve the efficiency of the lead-glass tiles trapping Cherenkov light for energy reconstruction and particle identification, we optimized the application of a highly reflective coating. Through viscosity and thickness control, masking, and a custom spray technique, we refined the coating process to reduce surface defects and improve light yield. Together, these efforts strengthen the ICARUS neutrino program and REDTOP's capability of detecting rare decay events.
Lepton Flavour Violation in Tau Decays at BaBar
Recent results from {tau} physics studies at BABAR are presented with an emphasis on Lepton Flavour Violation measurements. The results from the current generation of B-meson Factories are already beginning to constrain the parameter space of models that go beyond the Standard Model. By the end of their data-taking, the current generation of B-meson factories will have produced nearly 2 billion {tau} pair decays. The physics potential of this legacy has only just begun to be exploited.
Model-independent analysis of B → πℓ{sup +}ℓ{sup −} decays
The results obtained by calculating, on the basis of the Standard Model, the branching fractions for the decays B → πℓ{sup +}ℓ{sup −} (ℓ{sup ±} = e{sup ±}, µ{sup ±}) and the invariant-mass spectrum of dileptons for the process B{sup +} → π{sup +}ℓ{sup +}ℓ{sup −} are presented. The resulting theoretical estimates depend on the choice of model for the B → π transition form factors f{sub +}(q{sup 2}), f{sub 0}(q{sup 2}), and f{sub T} (q{sup 2}). However, one can get rid of this arbitrariness by employing experimental data or the results of QCD lattice calculations to determine the parameter dependence of the form factors. Data from B-meson factories were used to determine the dependence of the form factor f{sub +}(q{sup 2}) on the transfer momentum squared. Yet another required form factor, f{sub T} (q{sup 2}), was extracted from available lattice data on B → π and B → K transitions with allowance for nearly identical effects of the breakdown of flavor SU(3){sub F} symmetry in the respective form factors. The resulting value of the decay branching fraction, B(B{sup +} → π{sup +}µ{sup +}µ{sup −}) = (1.88{sub −0.21}{sup +0.32}) × 10{sup −8}, is in good agreement with the results of measurements of the LHCb Collaboration. The branching fraction for the isospin analog of the decay under consideration is B(B{sup +} → π{sup +}µ{sup +}µ{sup −}) = (0.94{sub −0.11}{sup +0.16}) × 10{sup −8}. Therefore, this decay can be measured at the Super-B factory under construction.
Measurement of Charmless B to Vector-Vector decays at BaBar
The authors present results of B {yields} vector-vector (VV) and B {yields} vector-axial vector (VA) decays B{sup 0} {yields} {phi}X(X = {phi},{rho}{sup +} or {rho}{sup 0}), B{sup +} {yields} {phi}K{sup (*)+}, B{sup 0} {yields} K*K*, B{sup 0} {yields} {rho}{sup +}b{sub 1}{sup -} and B{sup +} {yields} K*{sup 0}{alpha}{sub 1}{sup +}. The largest dataset used for these results is based on 465 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays, collected with the BABAR detector at the PEP-II B meson factory located at the Stanford Linear Accelerator Center (SLAC). Using larger datasets, the BABAR experiment has provided more precise B {yields} VV measurements, further supporting the smaller than expected longitudinal polarization fraction of B {yields} {phi}K*. Additional B meson to vector-vector and vector-axial vector decays have also been studied with a view to shedding light on the polarization anomaly. Taking into account the available errors, we find no disagreement between theory and experiment for these additional decays.
Advancement of LANSCE accelerator facility as a 1-MW Fusion Prototypic Neutron Source
The Fusion Prototypic Neutron Source (FPNS) is considered to be a testbed for scientific understanding of material degradation in future nuclear fusion reactors (Zinkle and Moeslang, 2013; Summary Report on the FPNS Workshop, 2018; Pitcher et al., 2019). The primary mission of FPNS is to provide a damage rate in iron samples of 8-11 dpa/calendar year with He/dpa ratio of 10 appm in irradiation volume of 50 cm 3 or larger with irradiation temperature 300–1000 °C and flux gradient less than 20%/cm in the plane of the sample. The Los Alamos Neutron Science Center (LANSCE) is an attractive candidate for the FPNS project. The Accelerator Facility was designed and operated for an extended period as a 0.8-MW Meson Factory. The existing setup of the LANSCE accelerator complex can nearly fulfill requirements of the fusion neutron source station. The primary function of the upgraded accelerator systems is the safe and reliable delivery of a 1.25-mA continuous proton beam current at 800-MeV beam energy from the switchyard to the target assembly to create 1 MW power of proton beam interacting with a solid tungsten target. The present study describes existing accelerator setup and further development required to meet the needs of FPNS project.
Spin-dependent scattering of sub-GeV dark matter: Models and constraints
We calculate the scattering rate of sub-GeV dark matter in solid-state targets for spin-dependent dark matter–nucleon interactions. For dark matter particles with mass below 100 MeV, the scattering occurs predominantly through incoherent phonon production. For dark matter heavier than 100 MeV, we match onto the nuclear recoil calculation. To compare the sensitivity of future direct detection experiments with existing constraints, we consider three models with interactions that are mediated by spin-0 or spin-1 particles. This allows us to derive bounds on the cross section from searches for the mediating particle, including bounds from stellar cooling, beam dump experiments, meson factories, and dark matter self-interactions. The existing bounds are very stringent, though for 𝑚 𝜒 ≳100 MeV there is parameter space, which may be accessible with direct detection, depending on the exposure and background rates.
Measurement and Interpretation of Moments in Inclusive Semileptonic Decays B-bar to X_c ell^-
We present results for the moments of observed spectra in inclusive semileptonic B-meson decays to charm hadrons {bar B} {yields} X{sub c} {ell}{sup -}{bar {nu}}. Moments of the hadronic-mass and the combined mass-and-energy spectra for different minimum electron or muon momenta between 0.8 and 1.9 GeV/c are obtained from a sample of 232 x 10{sup 6} {Gamma}(4S) {yields} B{bar B} events, collected with the BABAR detector at the PEP-II asymmetric-energy B-meson factory at SLAC. We also present a reevaluation of the moments of electron-energy spectra and partial decay fractions B({bar B} {yields} X{sub c}e{sup -}{bar {nu}}) for minimum electron momenta between 0.6 and 1.5 GeV/c based on a sample of 51 x 10{sup 6} {Gamma}(4S) {yields} B{bar B} events. The measurements are used for the extraction of the total decay fraction, the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |V{sub cb}|, the quark masses m{sub b} and m{sub c}, and four heavy-quark QCD parameters in the framework of a Heavy-Quark Expansion (HQE). We find B({bar B} {yields} X{sub c}{ell}{sup -}{bar {nu}}) = (10.64 {+-} 0.17 {+-} 0.06)% and |V{sub cb}| = (42.05 {+-} 0.45 {+-} 0.70) x 10{sup -3}.
New physics searches at kaon and hyperon factories
Rare meson decays are among the most sensitive probes of both heavy and light new physics. Among them, new physics searches using kaons benefit from their small total decay widths and the availability of very large datasets. On the other hand, useful complementary information is provided by hyperon decay measurements. We summarize the relevant phenomenological models and the status of the searches in a comprehensive list of kaon and hyperon decay channels. We identify new search strategies for under-explored signatures, and demonstrate that the improved sensitivities from current and next-generation experiments could lead to a qualitative leap in the exploration of light dark sectors.
The SuperB project
This paper presents a very short review of the SuperB project which aims to construct a new generation flavour factory with a designed luminosity of at least 10{sup 36} cm{sup -2} s{sup -1}. The main issues related to the physics programme, together with the description of the conceptual design of the accelerator and detector are briefly discussed.
Some problems in heavy-quarkonium decays
Problems proposed by the present authors for studies at c-τ, b, super-c-τ, and super-b factories are formulated. First, a comparison of the mechanisms of light-scalar-meson production in the process D{sub s}{sup +}→ss̄e{sup +}ν→[σ(600)+f{sub 0}(980)]e{sup +}ν→π{sup +}π{sup −}e{sup +}ν with the mechanisms of light-pseudoscalar-meson production in the process D{sub s}{sup +}→ss̄e{sup +}ν→(η/η{sup ′})e{sup +}ν reveals that the transition ss̄→σ(600) is negligible in relation to the transition ss̄→f{sub 0}(980). As for f{sub 0}(980), ss̄→f{sub 0}(980) is not more than 30% of ss̄→η{sub s}(η{sub s}=ss̄). It is proposed to study light scalar mesons in the semileptonic decays of D{sup +}(D{sup −}) D{sup 0}(D̄{sup 0}), B{sup +}(B{sup −}), and B{sup 0}(B̄{sup 0}). Second, interference phenomena observed in the ψ(3770)-resonance region in the reaction e{sup +}e{sup −}→DD̄ are described on the basis of models satisfying the elastic-unitarity requirement. As a model, we propose the model of mixed ψ(3770) and ψ(2S) resonances. In order to select theoretical models, it is proposed to employ non-DD̄ decay channels such as e{sup +}e{sup −} → ψ(3770) → γχ{sub c0}, J/ψη, and ϕη. Third, branching ratios are calculated for ψ(3770) and ϒ(10580) decays proceeding to light (non-DD̄ and non-BB̄) hadrons owing to the contributions of real DD̄ and BB̄ intermediate states. The predictions obtained for these branching ratios lie in the range of 1% ≲ BR ≲ 15%. The lower boundary of this range is ten times higher than the branching ratio for annihilation to three gluons.
Radiative and Leptonic B-meson Decays from the B-factories
Radiative and leptonic decays of B-mesons represent an excellent laboratory for the search for New Physics. I present here recent results on radiative and leptonic decays from the Belle and BABAR collaborations. Radiative penguin and leptonic B-meson decays are excellent probes for investigating the effects of New Physics. Although current measurements are in agreement with the Standard Model expectations, they are still quite useful for setting bounds on possible NP models. The B {yields} X{sub s}{gamma} and B {yields} {tau}{nu} measurements, for example, put strong constraints on the mass of charged Higgs bosons in Type II two-Higgs double models. The B {yields} X{sub s}{gamma} branching fraction measurements also constrain models with universal extra dimensions.
Prospects of charmonium studies in the Belle-II experiment
TheBelle-II experiment at the SuperKEKB super-B factorywill begin data acquisition in 2016, the expected integrated luminosity being 50 ab{sup -1}. A statistical data sample of record volume 50 times as large as that of the statistical data sample accumulated earlier at the Belle detector will make it possible to measure precisely the parameters of new exotic states discovered recently at B factories and to clarify the origin of these states.
Relativistic description of pair production of doubly heavy baryons in e{sup +}e{sup −} annihilation
Relativistic corrections in the pair production of S-wave doubly heavy diquarks in electron-positron annihilation were calculated on the basis of perturbative QCD and the quark model. The relativistic corrections to the wave functions for quark bound states were taken into account with the aid of the Breit potential in QCD. Relativistic effects change substantially the nonrelativistic cross sections for pair diquark production. The yield of pairs of (ccq) doubly heavy baryons at B factories was estimated.
Project of a Super Charm-Tau factory at the Budker Institute of Nuclear Physics in Novosibirsk
A project of a Super Charm-Tau factory is being developed at the Budker Institute of Nuclear Physics (Siberian Branch, Russian Academy of Sciences) in Novosibirsk. The electron-positron collider to be employed will operate at c.m. energies in the range between 2 and 5 GeV at an unprecedentedly high luminosity of 10{sup 35} cm{sup -2} s{sup -1} with a longitudinal electron polarization at the beam-interaction point. The main objective of experiments at the Super Charm-Tau factory is to study processes involving the production and properties of charmed quarks and tau leptons. A high luminosity of this setup will make it possible to obtain a statistical data sample that will be three to four orders of magnitude vaster than that from any other experiment performed thus far. Experiments at this setup are assumed to be sensitive to effects of new physics beyond the Standard Model. Investigations to be carried out at the Super-Charm-Tau factory will supplement future experiments at Super-B factories under construction in Italy and in Japan.
Results on charmonium-like states at BaBar
We present recent results on charmonium and charmonium-like states from the BaBar B-factory located at the PEP-II asymmetric energy e{sup +}e{sup -} storage ring at the SLAC National Accelerator Laboratory.