Closing the window on WIMP Dark Matter

We study scenarios where Dark Matter is a weakly interacting particle (WIMP) embedded in an ElectroWeak multiplet. In particular, we consider real SU(2) representations with zero hypercharge, that automatically avoid direct detection constraints from tree-level Z-exchange. We compute for the first time all the calculable thermal masses for scalar and fermionic WIMPs, including Sommerfeld enhancement and bound states formation at leading order in gauge boson exchange and emission. WIMP masses of few hundred TeV are shown to be compatible both with s-wave unitarity of the annihilation cross-section, and perturbativity. We also provide theory uncertainties on the masses for all multiplets, which are shown to be significant for large SU(2) multiplets. We then outline a strategy to probe these scenarios at future experiments. Electroweak 3-plets and 5-plets have masses up to about 16 TeV and can efficiently be probed at a high energy muon collider. We study various experimental signatures, such as single and double gauge boson emission with missing energy, and disappearing tracks, and determine the collider energy and luminosity required to probe the thermal Dark Matter masses. Larger multiplets are out of reach of any realistic future collider, but can be tested in future $$\gamma $$ γ -ray telescopes and possibly in large-exposure liquid Xenon experiments.

Interacting Shell Model Calculations for Neutrinoless Double Beta Decay of 82Se With Left-Right Weak Boson Exchange

In the present work, the λ mechanism (left-right weak boson exchange) and the light neutrino-exchange mechanism of neutrinoless double beta decay is studied. In particular, much attention is paid to the calculation of nuclear matrix elements for one of the neutrinoless double beta decaying isotopes 82Se. The interacting shell model framework is used to calculate the nuclear matrix element. The widely used closure approximation is adopted. The higher-order effect of the pseudoscalar term of nucleon current is also included in some of the nuclear matrix elements that result in larger Gamow-Teller matrix elements for the λ mechanism. Bounds on Majorana neutrino mass and lepton number violating parameters are also derived using the calculated nuclear matrix elements.

Prediction of an ΩbbbΩbbb Dibaryon in the Extended One-Boson Exchange Model

Since Yukawa proposed that the pion is responsible for mediating the nucleon-nucleon interaction, meson exchanges have been widely used in understanding hadron-hadron interactions. The most studied mesons are the σ, π, ρ, and ω, while other heavier mesons are often argued to be less relevant because they lead to short range interactions. However, whether the range of interactions is short or long should be judged with respect to the size of the system studied. We propose that one charmonium exchange is responsible for the formation of the ΩcccΩccc dibaryon, recently predicted by lattice QCD simulations. The same approach can be extended to the strangeness and bottom sectors, leading to the prediction on the existence of ΩΩ and ΩbbbΩbbb dibaryons, while the former is consistent with the existing lattice QCD results, the latter remains to checked. In addition, we show that the Coulomb interaction may break up the ΩcccΩccc pair but not the ΩbbbΩbbb and ΩΩ dibaryons.

Newly observed X(4630): a new charmoniumlike molecule

Very recently, the LHCb Collaboration at the Large Hadron Collider at CERN observed new resonance X(4630). The X(4630) is decoded as a charmoniumlike molecule with hidden-strange quantum number well in the one-boson-exchange mechanism. Especially, the study of its hidden-charmed decays explicitly shows the dominant role of $$J/\psi \phi $$ J / ψ ϕ among all allowed hidden-charmed decays of the X(4630), which enforces the conclusion of X(4630) as a charmoniumlike molecule. The discovery of the X(4630) is a crucial step of constructing charmoniumlike molecule zoo.

The influence of δ meson on the isospin splitting of in-medium NN → NΔ cross-sections

The isospin splitting of the in-medium [Formula: see text] cross-sections in asymmetric nuclear medium is investigated in the framework of the one-boson exchange model by including [Formula: see text] and [Formula: see text] mesons. Our results show that the medium correction factors [Formula: see text] have [Formula: see text] and [Formula: see text] by using the without-[Formula: see text] sets. By including the [Formula: see text] meson, there appear the totally opposite results in the [Formula: see text] for different channels, i.e., [Formula: see text] and [Formula: see text].

Underlying SUSY in a generalized Jaynes–Cummings model

We present a general qubit-boson interaction Hamiltonian that describes the Jaynes–Cummings model and its extensions as a single Hamiltonian class. Our model includes non-linear processes for both the free qubit and boson field as well as non-linear, multi-boson excitation exchange between them. It shows an underlying algebra with supersymmetric quantum mechanics features allowing an operator based diagonalization that simplifies the calculations of observables. As a practical example, we show the evolution of the population inversion and the boson quadratures for an initial state consisting of the qubit in the ground state interacting with a coherent field for a selection of cases covering the standard Jaynes–Cummings model and some of its extensions including Stark shift, Kerr-like, intensity dependent coupling, multi-boson exchange and algebraic deformations.

Quark-sector Lorentz violation in Z-boson production

Quark-sector Lorentz violation is studied in the context of Drell-Yan dilepton production including effects from Z-boson exchange. We show the chiral nature of the weak interactions enables parity-violating and spin-dependent effects to be studied using unpolarized initial states. Constraints are placed on dimensionless and CPT-even coefficients for Lorentz violation for the first two generations of quarks using measurements from the Large Hadron Collider.