We present the first lattice QCD calculation of the leading-order momentum-independent parity violating coupling between pions and nucleons, h 1 πNN . The calculation performs measurements on dynamical anisotropic clover gauge configurations, with a spatial extent of L ∼ 2.5 fm, a spatial lattice spacing of as ∼ 0.123 fm, and a pion mass of mπ ∼ 389 MeV. While this first calculation does not include non-perturbative renormalization of the bare parity-violating operators, a chiral extrapolation to the physical pion mass, or contributions from disconnected (quark-loop) diagrams, these are expected to result in systematic errors within the quoted statistical error. We find a contribution from the 'connected' diagrams of h 1,con πNN = (1.099 ± 0.505 +0.058 −0.064 ) × 10 −7 , consistent with current experimental bounds and previous model-dependent theoretical predictions.

Matrix elements of six-quark operators are needed to extract new physics constraints from experimental searches for neutron-antineutron oscillations. This work presents in detail the first lattice quantum chromodynamics calculations of the necessary neutron-antineutron transition matrix elements including calculation methods and discussions of systematic uncertainties. Implications of isospin and chiral symmetry on the matrix elements, power counting in the isospin limit, and renormalization of a chiral basis of six-quark operators are discussed. Calculations are performed with a chiral-symmetric discretization of the quark action and physical light quark masses in order to avoid the need for chiral extrapolation. Non-perturbative renormalization is performed, including a study of lattice cutoff effects. Excited-state effects are studied using two nucleon operators and multiple values of source-sink separation. Results for the dominant matrix elements are found to be significantly larger compared to previous results from the MIT bag model. Future calculations are needed to fully account for systematic uncertainties associated with discretization and finite-volume effects but are not expected to significantly affect this conclusion. * erinaldi@bnl.gov †

Composite dark matter candidates, which can arise from new strongly-coupled sectors, are wellmotivated and phenomenologically interesting, particularly in the context of asymmetric generation of the relic density. In this work, we employ lattice calculations to study the electromagnetic form factors of electroweak-neutral dark-matter baryons for a three-color, QCD-like theory with N f = 2 and 6 degenerate fermions in the fundamental representation. We calculate the (connected) charge radius and anomalous magnetic moment, both of which can play a significant role for direct detection of composite dark matter. We find minimal N f dependence in these quantities. We generate mass-dependent cross-sections for dark matter-nucleon interactions and use them in conjunction with experimental results from XENON100, excluding dark matter candidates of this type with masses below 10 TeV.PACS numbers: 11.10. Hi, 11.15.Ha, 95.35.+d Introduction Experimental bounds on the interaction of the dark matter with Standard-Model (SM) particles have strengthened by many orders of magnitude in recent years. In particular, dark-matter particles cannot have SMstrength couplings to electroweak gauge bosons, based on direct-detection constraints [1, 2]. At the same time, there is a strong motivation for the dark matter to couple to the SM in some way for the purpose of relic density generation, either as a thermal relic via the so-called "WIMP miracle" (see [3] for a recent review) or through an asymmetric scenario which may be related to the creation of baryon asymmetry [4][5][6][7][8][9][10][11]. Construction of dark matter models thus requires a careful balance between the presence and absence of dark-sector interactions with the SM.Composite dark matter models provide a simple mechanism for attaining this balance, one which can lead to interesting and unique phenomenology. By hypothesizing a new, confining gauge force in the dark sector, an electroweak-neutral composite dark matter candidate can be constructed as a bound state of electroweak-charged constituents. In this way, electroweak interactions can be active in the early Universe for the generation of relic density, but only neutral bound states survive to the present day. Electroweak coupling to the constituents is still possible, leading to form-factor suppressed interactions with the neutral composites. They can be roughly estimated from QCD analogs, but in general can be determined quantitatively only by lattice calculations.In this paper, we consider an underlying SU (3) gauge theory with fermions in the fundamental representation, but

We explore the interactions of two strangeness -3 baryons in multiple spin channels with lattice QCD. This system provides an ideal laboratory for exploring the interactions of multi-baryon systems with minimal dependence on light quark masses. Model calculations of the two-Ω − system in two previous works have obtained conflicting results, which can be resolved by lattice QCD.The lattice calculations are performed using two different volumes with L ∼ 2.5 and 3.9 fm on anisotropic clover lattices at m π ∼ 390 MeV with a lattice spacing of a s ∼ 0.123 fm in the spatial direction and a t ∼ a s /3.5 in the temporal direction. Using multiple interpolating operators from a non-displaced source, we present scattering information for two ground state Ω − baryons in both the S=0 and S=2 channels. For S=0, k cot δ is extracted at two volumes, which lead to an extrapolated scattering length of a ΩΩ S=0 = 0.16 ± 0.22 fm, indicating a weakly repulsive interaction. Additionally, for S=2, two separate highly repulsive states are observed. We also present results on the interactions of the excited strangeness −3, spin-1 2 states with the ground spin-3 2 states for the spin-1 and spin-2 channels. Results for these interactions are consistent with attractive behavior.