Abstract: We propose a novel scale-invariant model with the 3-3-1-1 gauge symmetry featuring a universal seesaw mechanism for all fermion masses, which, through the inclusion of additional vectorlike quarks, provides a partial explanation for the observed fermion mass hierarchies. A discrete remnant of the gauge group, the matter parity (P-M), stabilizes a fermionic dark matter candidate, and the scalar sector includes two triplets (minimal for 3-3-1 breaking) and two scalar singlets. We identify the lightest P-M-odd fermion, f(d), as a viable dark matter candidate. Our analysis shows that f(d) satisfies the observed relic density constraint within the mass range 220 GeV less than or similar to mf(d) less than or similar to 555 GeV, primarily due to resonant annihilation via the new scalar H-2. While this mass range depends on the symmetry-breaking scale v(chi), which has a lower bound of v(chi) greater than or similar to 3.6 TeV from LEP constraints on the rho(0) parameter, we adopt a more conservative lower bound of v(chi) >10 TeV. This choice is made to ensure that the Z ' boson mass remains above approximately 4 TeV, and is motivated by recent LHC results and future projections for Z ' boson searches, which provide more stringent constraints than previous bounds or those from the rho(0) parameter. Spin-independent (SI) interactions dominate the direct detection phenomenology of f(d). We calculate the SI elastic scattering cross section and find that parameter points satisfying the relic density constraint are consistent with current experimental limits from LZ and PandaX-4T for certain parameter choices, particularly depending on the alpha(12) angle. Some regions of the viable parameter space lie below the neutrino floor. Prospects for detection by future experiments like XLZD and PandaX-xT are also presented and discussed.

Abstract: Fermionic asymmetric dark matter (ADM) can be captured in neutron stars (NSs) via scatterings with the star constituents. The absence of dark matter annihilation due to its asymmetric nature leads to ADM accumulation in the NS core, potentially reaching densities sufficient to exceed the Chandrasekhar limit and trigger its gravitational collapse into a black hole (BH), eventually consuming the NS from within. Therefore, the existence and observation of old neutron stars provide a means to constrain the properties of ADM. We revisit previous constraints on the mass and scattering cross section off neutrons of fermionic ADM across a class of models. We critically examine common simplifying approximations used in the literature to derive these limits. Our analysis includes improved treatments of dark matter capture, thermalization, BH formation, accretion, and evaporation. We find that previous results can be relaxed by a few orders of magnitude once these effects are properly accounted for.

Abstract: An angular analysis of the B-s(0)-> phi e(+)e(-) decay is performed using the proton-proton collision dataset collected between 2011 and 2018 by the LHCb experiment, corresponding to an integrated luminosity of 9 fb(-1) at centre-of-mass energies of 7, 8 and 13 TeV. The analysis is performed in the very low dielectron invariant mass-squared region between 0.0009 and 0.2615 GeV2/c(4). The longitudinal polarisation fraction of the phi meson is measured to be less than 11.5% at 90% confidence level. The A(T)(ReCP) observable, which is related to the lepton forward-backward asymmetry, is measured to be 0.116 +/- 0.155 +/- 0.006, where the first uncertainty is statistical and the second systematic. The transverse asymmetries, A(T)((2)) and A(T)(ImCP), which are sensitive to the virtual photon polarisation, are found to be -0.045 +/- 0.235 +/- 0.014 and 0.002 +/- 0.247 +/- 0.016, respectively. The results are consistent with Standard Model predictions.