Symmetric Mass Generation in Lattice Gauge Theory

We construct a four-dimensional lattice gauge theory in which fermions acquire mass without breaking symmetries as a result of gauge interactions. Our model consists of reduced staggered fermions transforming in the bifundamental representation of an SU(2)×SU(2) gauge symmetry. This fermion representation ensures that single-site bilinear mass terms vanish identically. A symmetric four-fermion operator is however allowed, and we give numerical results that show that a condensate of this operator develops in the vacuum.

Shift-type SMEFT effects in dileptons at the LHC

We explore the constraints which can be derived on Wilson coefficients in the Standard Model Effective Field Theory from dilepton production, notably including the constraints on operators which do not lead to cross sections growing with energy relative to the Standard Model rate, i.e. shifts. We incorporate essential theory error estimates from higher EFT orders in the analysis in order to provide robust bounds. We find that constraints on four-fermion operator contributions which do grow with energy are not materially weakened by the inclusion of these shifts, and that a constraint on the shifts can also be derived, with a characteristic strength comparable to, and a directionality in parameter space complementary to, those from LEP data. This completes the study of hadronically-quiet dilepton production in the SMEFT, and provides two new constraints which are linearly independent from others arising at the LHC and also rotated in Wilson coefficient space relative to, though not completely independent from, the LEP bounds.

Inclusive and Exclusive Decay of B- Meson

In our letter we deal with the inclusive and exclusive decay of B- meson. The inclusive b→dγ decay has been considered here including the QCD corrections to the Wilson coefficients and the matrix elements of the operators in the effective Hamiltonian. We calculate the O(αs) virtual corrections to the matrix element for b→dγ, taking into account the contributions of the four-fermion operator O2 and the electromagnetic and color dipole type operators. It drastically reduces the large scale dependence of the leading logarithmic approximation. Moreover, while we are considering the exclusive B-→ρ-γ decay, we have taken into consideration both the short distance as well as long distance contributions. Therefore, we have obtained better result for the partial decay width of B-→ρ-γ.

ACCELERATING WILSON FERMION MATRIX INVERSIONS BY MEANS OF THE STABILIZED BICONJUGATE GRADIENT ALGORITHM

The stabilized biconjugate gradient algorithm BiCGStab recently presented by van der Vorst is applied to the inversion of the lattice fermion operator in the Wilson formulation of lattice Quantum Chromodynamics. Its computational efficiency is tested in a comparative study against the conjugate gradient and minimal residual methods. Both for quenched gauge configurations at β=6.0 and gauge configurations with dynamical fermions at β=5.4, we find BiCGStab to be superior to the other methods. BiCGStab turns out to be particularly useful in the chiral regime of small quark masses.

LAUGHLIN STATES AT THE EDGE

An effective wavefunction for the edge excitations in the Fractional quantum Hall effect can be found by dimensionally reducing the bulk wavefunction. Treated this way the Laughlin ν = 1/(2n + 1) wavefunction yields a Luttinger model ground state. We identify the edge-electron field with a Luttinger hyper-fermion operator, and the edge electron itself with a non-backscattering Bogoliubov quasi-particle. The edge-electron propagator may be calculated directly from the effective wavefunction using the properties of a one-dimensional one-component plasma, provided a prescription is adopted which is sensitive to the extra flux attached to the electrons.