Sensitivity of the SHiP experiment to light dark matter

Dark matter is a well-established theoretical addition to the Standard Model supported by many observations in modern astrophysics and cosmology. In this context, the existence of weakly interacting massive particles represents an appealing solution to the observed thermal relic in the Universe. Indeed, a large experimental campaign is ongoing for the detection of such particles in the sub-GeV mass range. Adopting the benchmark scenario for light dark matter particles produced in the decay of a dark photon, with αD = 0.1 and mA′ = 3mχ, we study the potential of the SHiP experiment to detect such elusive particles through its Scattering and Neutrino detector (SND). In its 5-years run, corresponding to 2 · 1020 protons on target from the CERN SPS, we find that SHiP will improve the current limits in the mass range for the dark matter from about 1 MeV to 300 MeV. In particular, we show that SHiP will probe the thermal target for Majorana candidates in most of this mass window and even reach the Pseudo-Dirac thermal relic.

Accidental SO(10) axion from gauged flavour

An accidental U(1) Peccei-Quinn (PQ) symmetry automatically arises in a class of SO(10) unified theories upon gauging the SU(3)f flavour group. The PQ symmetry is protected by the ℤ4 × ℤ3 center of SO(10) × SU(3)f up to effective operators of canonical dimension six. However, high-scale contributions to the axion potential posing a PQ quality problem arise only at d = 9. In the pre-inflationary PQ breaking scenario the axion mass window is predicted to be ma ∈ [7 × 10−8, 10−3] eV, where the lower end is bounded by the seesaw scale and the upper end by iso-curvature fluctuations. A high-quality axion, that is immune to the PQ quality problem, is obtained for ma ≳ 2 0.02 eV. We finally offer a general perspective on the PQ quality problem in grand unified theories.

Studies of the resonance components in the $$B_s$$ decays into charmonia plus kaon pair

In this work, the decays of $$B_s$$Bs meson to a charmonium state and a $$K^+K^-$$K+K- pair are carefully investigated in the perturbative QCD approach. Following the latest fit from the LHCb experiment, we restrict ourselves to the case where the produced $$K^+K^-$$K+K- pair interact in isospin zero S, P, and D wave resonances in the kinematically allowed mass window. Besides the dominant contributions of the $$\phi (1020)$$ϕ(1020) resonance in the P-wave and $$f_2'(1525)$$f2′(1525) in the D-wave, other resonant structures in the high mass region as well as the S-wave components are also included. The invariant mass spectra for most of the resonances in the $$B_s\rightarrow J/\psi K^+K^-$$Bs→J/ψK+K- decay are well reproduced. The obtained three-body decay branching ratios can reach the order of $$10^{-4}$$10-4, which seem to be accessible in the near future experiments. The associated polarization fractions of those vector-vector and vector-tensor modes are also predicted, which are compared with the existing data from the LHCb Collaboration.

Numerical and experimental studies on the energy performance of thermal mass windows

Thermal mass window is a transparent water storage envelope for improving energy efficiency of building. Currently, the embedded algorithms in all energy simulation programs disable the explicit energy simulation of building zones with thermal mass windows. The energy simulation methodology for building zones with thermal mass windows, as well as the comparative experiment for testing their energy performance, is presented in the article. For solving the inherent energy simulation problem, the integrated numerical approach based on the simplified one-dimensional nodal thermal model and the optical model was proposed. In a case study, the numerical approach was applied to an office-building zone with a typical thermal mass window to investigate its energy performance. Meanwhile, a comparative experiment on two thermal boxes with and without thermal mass windows under the identical outdoor conditions was also performed for the verification of energy performance of thermal mass windows. Both the simulation and the experimental results reveal that thermal mass windows can outperform conventional glazing in terms of thermal performance and energy efficiency. Shaded thermal mass windows in summer can produce cooling load reduction, while exposed ones in sunny winter days contribute to heating load reduction, which is beneficial for building energy saving.

Fast open modification spectral library searching through approximate nearest neighbor indexing

Open modification searching (OMS) is a powerful search strategy that identifies peptides carrying any type of modification by allowing a modified spectrum to match against its unmodified variant by using a very wide precursor mass window. A drawback of this strategy, however, is that it leads to a large increase in search time. Although performing an open search can be done using existing spectral library search engines by simply setting a wide precursor mass window, none of these tools have been optimized for OMS, leading to excessive runtimes and suboptimal identification results. Here we present the ANN-SoLo tool for fast and accurate open spectral library searching. ANN-SoLo uses approximate nearest neighbor indexing to speed up OMS by selecting only a limited number of the most relevant library spectra to compare to an unknown query spectrum. This approach is combined with a cascade search strategy to maximize the number of identified unmodified and modified spectra while strictly controlling the false discovery rate, as well as a shifted dot product score to sensitively match modified spectra to their unmodified counterparts. ANN-SoLo achieves state-of-the-art performance in terms of speed and the number of identifications. On a previously published human cell line data set, ANN-SoLo confidently identifies more spectra than SpectraST or MSFragger and achieves a speedup of an order of magnitude compared to SpectraST.ANN-SoLo is implemented in Python and C++. It is freely available under the Apache 2.0 license athttps://github.com/bittremieux/ANN-SoLo.

Improvements in identification and quantitation of pesticide residues in food by LC-QTOF using sequential mass window acquisition (SWATH®)

The efficiency of a data independent acquisition by the sequential window acquisition of all theoretical fragment ions (SWATH®) in high resolution accurate mass spectrometry was evaluated for pesticide residue analysis.