Moduli stabilization in stringy ISS models

We present a stringy realization of the ISS metastable SUSY breaking model with moduli stabilization. The mass moduli of the ISS model is stabilized by gauging of a U(1)$U(1)$ symmetry and its D-term potential. The SUSY is broken both by F-terms and D-terms. It is possible to obtain de Sitter vacua with a vanishingly small cosmological constant by an appropriate fine-tuning of flux parameters.     

Radiative corrections to quark-lepton mass matrices in superstring-inspired models

We examine if quark-lepton mass matrices are modified by generation changing currents in superstring-inspired models. It is shown that sufficiently large corrections to the quark mass matrices can be derived in an SU(3)_C × SU(2)_L × SU(2)_R × U(1)_L × U(1)_R model with δ ⩾ 2 and an SU(3)_C × SU(2)_L × U(1)_L × U(1)_R model. Consistency with other experiments are investigated by means of renormalization group equations.     

Gauge coupling and fermion mass relations in low string scale brane models

We analyze the gauge coupling evolution in brane inspired models with U(3) x U(2) x U(1)^N symmetry at the string scale. We restrict our work to the case of brane configurations with two and three abelian factors (N = 2,3) and where only one Higgs doublet is coupled to down quarks and leptons and only one to the up quarks. We find that the correct hypercharge assignment of the standard model particles is reproduced for six viable models distinguished by different brane configurations. We investigate the third generation fermion mass relations and find that the correct low energy m_b/m_τ ratio can be obtained for b-τ Yukawa coupling equality at a string scale as low as M_S~10³ TeV. Received: 30 August 2005, Published online: 16 November 2005 PACS: 11.25.Wx, 11.25.Uv, 12.10.Kt     

Screening in three-dimensional QED with arbitrary fermion mass

We compute the quark–antiquark potential in three-dimensional massive quantum electrodynamics for an arbitrary fermion mass. The result indicates that screening prevails for any quark masses, contrary to the classical expectations, generalizing our previous result obtained for large masses. We also test the validity of several approximation schemes using a detailed numerical analysis. The classical result is still reproduced for a small separation of the quarks. Received: 16 May 2000 / Published online: 25 September 2000     

Tevatron constraints on the Higgs boson mass in the fourth-generation fermion models revisited

Recent Tevatron exclusion interval of the masses of Higgs boson considerably reduces in case of the light quasistable fourth generation neutral lepton.     

Theory of fermion field with zero mass

A theory is constructed for a free fermion field with spin 1/2 and zero mass, on the basis of the equation (d+a₅-b)(x) = 0, wherea ² = b² = 1. The theory is invariant against continuous Lorentz transformation. It is also invariant against combined Landau reflection, time reversal, and the Schwinger strong space-time inversion, but is not invariant against space reflection or change transformation. An important role is played in this theory by the appearance of projectors. The latter arise as a result of the presence of a zero divisor in the mass term of the equation. They enter in the normalization conditions for the solutions of the equation, and hence in all the conserved operators and their eigenfunctions. Results of the analogous researches by Tokuoka [20] and Gupta [21] are also discussed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 7–12, December, 1970.In conclusion, the author is grateful to Professor S. V. Izmailov for his attention and interest in discussions of the work.     

On the corrections to scaling in three-dimensional Ising models

The leading correction-to-scaling amplitudes for the spin-1/2, nearest-neighbor sc, bcc, and fee Ising models are considered with the particular aim of determining their signs. On the basis of previous two-variable series analyses by Chen, Fisher, and Nickel and renormalization group=4–d expansions, it is concluded that the correction amplitudes for the susceptibility, correlation length, specific heat, and spontaneous magnetization arenegative for all three lattices. Thus, for example, the effective exponent _eff(T) asymptotically approaches the true susceptibility exponent fromabove. Other earlier and more recent high-temperature series and field-theoretic analyses are seen to be consistent with this result. However, the usual nonasymptotic, perturbative field-theoretic approaches are essentially committed to positive correction amplitudes. The question of the signs therefore relates directly to the applicability of these non-asymptotic field-theoretic calculations to three-dimensional Ising models as well as to different experimental systems.     

Ambiguities in zeroth order fermion mass matrices

The six quark Weinberg-Salam model with the symmetry of the three generation permutation group S₃ has an extra O(2) pseudosymmetry when the Higgs fields lie in an S₃ doublet. We use this model as a prototype to question the derivation of zeroth order relations between fermion mixing angles and fermion masses.     

Curing fermion mass gauge variance in QED

The problem of the gauge dependence of the fermion mass in the Maxwell-Chern-Simons QED is revisited. Using Proca mass term as an intermediate infrared regulator we are demonstrating gauge-invariance of the fermion mass shell in QED in all orders of the perturbation theory.     

A mechanism for fermion mass generation

We present a mechanism for fermion mass generation, and apply it to the lepton sector of the Weinberg-Salam model. Extra fields, necessary to produce the large mass splittings of the observed fermions, form bound states more massive than the electroweak scale.     

On the dynamical vacuum rearrangement and the problem of fermion mass generation

We discuss the conditions under which the dynamical fermion mass generation mechanism may occur. The analogy between the vacuum rearrangement in massless electrodynamics, which results in the generation of a physical fermion mass, and the vacuum rearrangement concerned with the fall into the Coulomb centre with a large charge (Z > 137) is considered.     

Radiative corrections in compactified superstring models

One-loop corrections to the effective potential in models obtained from compactification of ten-dimensional superstring theories are calculated. It is found that no masses are generated for gauge non-singlet scalars even in the presence of supersymmetry breaking terms induced by gauge and gaugino condensation, but that the gravitino mass is determined at one loop. The scales of grand unification, supersymmetry breaking and condensation are fixed by the gauge singlet scalars and are found to be close to Planck scale. Requiring M_GUT<M_Planck restricts the other parameters of the theory. The one-loop effective potential at scales between the condensate and compactification scales is also discussed, with possible implications for the allowed particle content of the effective theory.     

Properties of fermion mixings in intersecting D-brane models

We consider the Yukawa couplings for quarks and leptons in the context of Pati–Salam model using intersecting D-brane models where the Yukawa coupling matrices are rank one in a simple choice of family replication. The CKM mixings can be explained by perturbing the rank 1 matrix using higher order terms involving new Higgs fields available in the model. We show that the near bi-large neutrino mixing angles can be naturally explained, choosing the light neutrino mass matrix to be type II seesaw dominant. The predicted value of U_e3$U_{e3}$ is in the range ?0.05–0.15$?0.05\text{–}0.15$. In the quark sector, V_cb$V_{cb}$ is naturally close to the strange/bottom quark mass ratio and we obtain an approximate relation V_ubV_cb?(ms/mb)²V_us$V_{ub}{V}_{cb}?{(m_s/m_b)}^2{V}_{us}$. The geometrical interpretations of the neutrino mixings are also discussed.