International Journal of Modern Physics A

This review summarizes results on the production cross-section measurements of electroweak boson pairs (WW, WZ, ZZ, Wγ and Zγ) at the Large Hadron Collider (LHC) in pp collisions at a center-of-mass energy of . The two general-purpose detectors at the LHC, ATLAS and CMS recorded an integrated luminosity of ≈5 fb^-1 in 2011, which offered the possibility to study the properties of diboson production to high precision. These measurements test predictions of the Standard Model (SM) in a new energy regime and are crucial for the understanding and the measurement of the SM Higgs boson and other new particles. In this review, special emphasis is drawn on the combination of results from both experiments and a common interpretation with respect to state-of-the-art SM predictions.

The newly discovered boson was only observed in diboson final states. The measurement of the fermionic decay modes of this new particle is essential to establish its compatibility with the Standard Model Higgs boson. The two main final states accessible at the LHC are the decay into pairs of b quarks and τ leptons, both of which are experimentally challenging. In some cases, the exploitation of specific Higgs boson production modes allows to significantly increase the experimental sensitivity. One can also extend the search by looking for di-muon final states. This article gives an overview of the Higgs boson searches in these three fermionic final states at the ATLAS and CMS experiments, focusing on the most recent developments and results.

Recent lattice QCD results are reviewed with an emphasis on spectroscopic results concerning the charm quark. It is demonstrated that, with accurate computations from lattice QCD in recent years that can be compared with the existing or upcoming experiments, stringent test of the Standard Model can be performed which will greatly sharpen our knowledge on the strong interaction.

In this review, we discuss the effects of quantum gravity on black hole physics. After a brief review of the origin of the minimal observable length from various quantum gravity theories, we present the tunneling method. To incorporate quantum gravity effects, we modify the Klein–Gordon equation and Dirac equation by the modified fundamental commutation relations. Then we use the modified equations to discuss the tunneling radiation of scalar particles and fermions. The corrected Hawking temperatures are related to the quantum numbers of the emitted particles. Quantum gravity corrections slow down the increase of the temperatures. The remnants are observed as . The mass is quantized by the modified Wheeler–DeWitt equation and is proportional to n in quantum gravity regime. The thermodynamical property of the black hole is studied by the influence of quantum gravity effects.

We review the beginning of the effective Lagrangian in QED that was first introduced in the literature by W. Heisenberg and H. Euler in 1936. Deviating from their way of calculating the one-loop effective correction to the classical Maxwell Lagrangian, we use Green's functions and adopt the Fock–Schwinger proper-time method. The important role of the Heisenberg–Euler effective Lagrangian is explicitly demonstrated for low-energy photon–photon processes.

Measurable parameters of the electron indicate that its background should be described by the Kerr–Newman (KN) solution. The spin/mass ratio of the electron is extreme large and the black hole (BH) horizons disappear, opening a topological defect of space–time — the Kerr singular ring of Compton size, which may be interpreted as a closed fundamental string to low-energy string theory. The singular and two-sheeted structure of the corresponding Kerr space has to be regularized, and we consider the old problem of regularizing the source of the KN solution. As a development of the earlier Keres–Israel–Hamity–López model, we describe the model of smooth and regular source forming a gravitating and relativistically rotating soliton based on the chiral field model and the Higgs mechanism of broken symmetry. The model reveals some new remarkable properties: (1) the soliton forms a relativistically rotating bubble of Compton radius, which is filled by the oscillating Higgs field in a pseudo-vacuum state; (2) the boundary of the bubble forms a domain wall which interpolates between the internal flat background and the external exact KN solution; (3) the phase transition is provided by a system of chiral fields; (4) the vector potential of the external KN solution forms a closed Wilson loop which is quantized, giving rise to a quantized spin of the soliton and (5) the soliton is bordered by a closed string, which is a part of the general complex stringy structure.

The process of neutrino production of electron–positron pairs in a magnetic field of arbitrary strength, where electrons and positrons can be created in the states corresponding to excited Landau levels, is analyzed. The mean value of the neutrino energy loss due to the process ν → νe^-e⁺ is calculated. The result can be applied for calculating the efficiency of the electron–positron plasma production by neutrinos in the conditions of the Kerr black hole accretion disk considered by experts as the most possible source of a short cosmological gamma burst. The presented research can also be useful for further development of the calculation technique for an analysis of quantum processes in external active medium, and in part in the conditions of moderately strong magnetic field, when taking account of the ground Landau level appears to be insufficient.

The approximate chiral invariance of the two-flavor (QCD) is known to be spontaneously broken. This effect explains the relatively small pion mass and, as is widely believed, the mass splittings of would-be chiral partners — the hadrons of equal spin but opposite parity lying in one multiplet of the chiral symmetry. We present experimental evidences that in reality such mass splittings in the meson sector seem to be approximately flavor-independent in all cases where they can be tested experimentally — the spin 0 and 1. In addition, a partial flavor independence holds for spin-1/2 baryons (namely among states in which at least one of the quark is not u or d one). This property allow to predict masses and quantum numbers for 10 new hadrons. The given flavor-independence, if confirmed for higher spins, hints at the existence of universal scale Λ_strong~300 MeV in the strong interactions which, in contrast to Λ_QCD, is flavor and scheme independent. Some manifestations of Λ_strong are discussed.

We present a systematic study of the noncommutative interaction of gravitational waves with matter at the quantum mechanical level in the long wavelength and small velocity limit. In particular, the noncommutative quantum dynamics of the Landau's problem is employed to measure the transmission amplitudes in terms of the Riemann's tensor elements by a gravitational wave in linearized approximation. It turns out that the Hamiltonian of the charged particles derived based on DeWitt's approach is valid by the deformed electromagnetic fields.

This paper is an extension for spinor fields the recently developed Dynamical Bridge formalism which relates a linear dynamics in a curved space to a nonlinear dynamics in Minkowski space. This leads to a new geometrical mechanism to generate a chiral symmetry breaking without mass, providing an alternative explanation for the absence of right-handed neutrinos. We analyze a spinor field obeying the Dirac equation in a curved space which is constructed by its own current. This way, both chiralities of the spinor field satisfy the same dynamics in the curved space. Afterward, the dynamical equation is re-expressed in terms of the flat Minkowski space and then each chiral component behaves differently. The left-handed part of the spinor field satisfies the Dirac equation while the right-handed part is trapped by a Nambu–Jona-Lasinio type potential.

It is shown that, in the supersymmetric smooth hybrid inflation model with the minimal Kähler potential, the spectral index n_s is larger than 0.97 in the standard inflation. In this context, we study the smooth hybrid inflationary model in the framework of the Randall–Sundrum type-II braneworld model. We derive all known inflationary spectrum parameters which are widely consistent with Planck data for a particular choice of brane tension values λ especially for number of e-folds N = 50. We reproduce the central value of the scalar spectral index n_s = 0.96 whereas the ratio r~(10^-4-10^-3). However, the running of the scalar spectral index is not excluded from the range given by the latest observational measurements.

We study the radial quantization of the 3dO(N) vector model. We calculate the higher spin charges whose commutation relations give the higher spin algebra. The Fock states of higher spin gravity in AdS₄ are realized as the states in the 3d CFT. The dynamical information is encoded in their inner products. This serves as the simplest explicit demonstration of the CFT definition for the quantum gravity.

We analyze the anomalous quartic gauge boson couplings WWγγ and ZZγγ, described by dimension-six effective quartic Lagrangian at the LHC. The sensitivities to anomalous quartic gauge couplings by examining the two different photon-induced processes pp → pγp → pWγqX and pp → pγp → pZZqX with W and Z's decaying leptonically are investigated. We show that γp mode of photon-induced reactions at the LHC are able to probe these couplings to the order of 10^-6–10^-7GeV^-2 at 95% confidence level (C.L.) with and for proton–proton luminosities in the range of 30–200 fb^-1.

We study spherically symmetric solutions of an SO(5) Chern–Simons–Yang–Mills–Higgs system in 3+1 dimensions. The Chern–Simons densities are defined in terms of both Yang–Mills fields and a five-component isomultiplet Higgs. The SO(3) × SO(2) solutions are analyzed in a systematic way, by employing numerical methods. These finite energy configurations possess both electric and magnetic global charges, differing radically, however, from Julia–Zee dyons. When two or more of these Chern–Simons densities are present in the Lagrangian, solutions with vanishing electric charge but nonvanishing electrostatic potential may exist.

We study the relationship between the family number of chiral fermions and the Wilson line phases, based on the orbifold family unification. We find that flavor numbers are independent of the Wilson line phases relating extra-dimensional components of gauge bosons, as far as the standard model gauge symmetry is respected. This feature originates from a hidden quantum-mechanical supersymmetry.

A gradual transition to the reflecting scattering mode developing already at the LHC energies is affecting multiparticle production dynamics, in particular, relation of the centrality with the impact parameter values of pp-collisions. We discuss the issues in the framework of the geometrical picture for the multiparticle production processes proposed by Chou and Yang. We consider effects of reflective scattering mode presence for the inclusive cross-sections.