International Journal of Modern Physics A

In experiments at the luminosity frontier, New Physics is being searched for in precision studies of rare processes. The most important example of such an effort is experiments at B factories and super B factories. While B factories have fully established the CKM quark transition matrix as the only source of CP violation in the Standard Model, the next generation of B factories, the so-called super B factories, will look for departures from the Standard Model. To collect a 50 times larger data sample, needed to reach the required sensitivity, a substantial B factory upgrade is being carried out. The SuperKEKB accelerator complex is designed for an increase in luminosity by a factor of 40. The upgraded Belle II spectrometer is being constructed to operate at considerably higher event rates, as well as higher backgrounds, accompanied by an increase in occupancy and radiation damage. Higher event rates also require substantial modifications in the trigger scheme, data acquisition system and computing. The paper discusses the detectors at B factories, the motivation for SuperKEKB/Belle II, the super B factory at KEK, as well as the requirements for the new accelerator and for the new detector. The present status of the project will be presented together with plans for the future. We will also discuss its competition, the LHCb experiment at the LHC.

Experiments on neutrino oscillations have uncovered several small parameters, θ₁₃ being a prominent one. Others are the solar mass splitting vis-à-vis the atmospheric one and the deviation of θ₂₃ from maximal mixing. In this talk, (talk given at the International Conference on Massive Neutrinos, Singapore, 9–13 February 2015) we elaborate on a neutrino mass model based on the see-saw mechanism in which the mixing angles to start with are either vanishing (θ₁₃ and θ₁₂) or π/4 (θ₂₃). The atmospheric mass splitting is taken as a part of this initial structure but the solar splitting is absent. A perturbative contribution, originating from a Type-I see-saw, results in nonzero values of θ₁₃, θ₁₂, , and shifts θ₂₃ slightly from π/4, interrelating them all. The model incorporates CP-violation, the phase δ being close to 3π/2 for (a) quasidegeneracy or (b) inverted mass ordering. It will be put to test as the neutrino parameters get better determined.

Recent progress is presented on higher-order calculations for the mass spectrum of Higgs particles in the CP-conserving and CP-violating MSSM, covering diagrammatic two-loop calculations for neutral and charged Higgs bosons as well as all-order resummation of large logarithms arising from the strong and Yukawa coupling sectors.

We discuss the role of iϵ in quantum field theories and suggest that it can be identified with the dimensional regularization parameter iϵ = 4-d thus clarifying and simplifying issues related to the infrared divergences without altering any of the present knowledge in QFT. We further present the relevance of this assumption for the optical theorem.

We analyze the nonrelativistic quantum dynamics of a single neutral spin-half particle, with nonzero magnetic and electric dipole moments, moving in an external electromagnetic field in the presence of a Lorentz-symmetry violating background. We also study the geometric phase for this model taking in account the influence of the parameter that breaks the Lorentz-symmetry. These geometric phases are used to impose an upper bound on the background magnitude.

Many cosmological scenarios envisage either a bounce of the universe at early times, or a collapse locally to form a black hole which re-expands into a new expanding universe region. Energy conditions preclude this phenomena for ordinary matter in general relativistic universe, but scalar or other types of fields can violate some of these conditions, and so can, possibly, provide conditions for a bouncing universe. In this paper, we have investigated the necessary conditions for a bounce in Kantowski–Sachs (KS) and Bianchi type models in some modified theories of gravity like Hoyle–Narlikar creation field theory, Lyra geometry, general class of scalar–tensor theories, Einstein's theory with variable cosmological term.

Following the suggestion of Alexei Morozov, Andrey Morozov and Anton Morozov, Phys. Lett. B737, 48 (2014), arXiv:1407.6319, to lift the knot polynomials for virtual knots and links from Jones to HOMFLY, we apply the evolution method to calculate them for an infinite series of twist-like virtual knots and antiparallel two-strand links. Within this family one can check topological invariance and understand how differential hierarchy is modified in virtual case. This opens a way towards a definition of colored (not only cabled) knot polynomials, though problems still persist beyond the first symmetric representation.

Extra neutral gauge bosons suggested by models beyond the standard model can indirectly show up in e⁺e^- collisions through off-resonance deviations of various physical observables from the corresponding standard model values. We considered leptonic observables and studied the dependence of the deviations on the polarizations of the positron and electron beams. We showed that, for a given model, the magnitude of the deviation of a given observable can attain its maximum value if the polarizations of the positron and electron beams are properly chosen. We determined, for a given model, a single set of beam polarization so that if this set is employed in measuring all considered observables, it produces the highest extra gauge boson discovery limits.

The Bialas–Bzdak model of elastic proton–proton scattering assumes a purely imaginary forward scattering amplitude, which consequently vanishes at the diffractive minima. We extended the model to arbitrarily large real parts in a way that constraints from unitarity are satisfied. The resulting model is able to describe elastic pp scattering not only at the lower ISR energies but also at in a statistically acceptable manner, both in the diffractive cone and in the region of the first diffractive minimum. The total cross-section as well as the differential cross-section of elastic proton–proton scattering is predicted for the future LHC energies of , 14, 15 TeV and also to 28 TeV. A nontrivial, significantly nonexponential feature of the differential cross-section of elastic proton–proton scattering is analyzed and the excitation function of the nonexponential behavior is predicted. The excitation function of the shadow profiles is discussed and related to saturation at small impact parameters.

Based on the first principle calculation, a Lagrangian for the system describing quarks, gluons, and their interactions, is constructed. Ascribed to the existence of dissipative behavior as a consequence of strong interaction within quark–gluon plasma (QGP) matter, auxiliary terms describing viscosities are constituted into the Lagrangian. Through a "kind" of phase transition, gluon field is redefined as a scalar field with four-vector velocity inherently attached. Then, the Lagrangian is elaborated further to produce the energy–momentum tensor of dissipative fluid-like system and the equation of motion (EOM). By imposing the law of energy and momentum conservation, the values of shear and bulk viscosities are analytically calculated. Our result shows that, at the energy level close to hadronization, the bulk viscosity is bigger than shear viscosity. By making use of the conjectured values η/s~1/4π and ζ/s~1, the ratio of bulk to shear viscosity is found to be ζ/η>4π.

The Higgs mass value is derived from a Hamiltonian on the Lie group U(3) where we relate strong and electroweak energy scales. The baryon states of nucleon and delta resonances originate in specific Bloch wave degrees of freedom coupled to a Higgs mechanism which also gives rise to the usual gauge boson masses. The derived Higgs mass is around 125 GeV. From the same Hamiltonian, we derive the relative neutron to proton mass ratio and the N and Delta mass spectra. All compare rather well with the experimental values. We predict scarce neutral flavor baryon singlets that should be visible in scattering cross-sections for negative pions on protons, in photoproduction on neutrons, in neutron diffraction dissociation experiments and in invariant mass spectra of protons and negative pions in B-decays. The fundamental predictions are based on just one length scale and the fine structure constant. More particular predictions rely also on the weak mixing angle and the up–down quark flavor mixing matrix element. With differential forms on the measure-scaled wave function, we could generate approximate parton distribution functions for the u and d valence quarks of the proton that compare well with established experimental analysis.