International Journal of Modern Physics A

The discovery of the Higgs boson has been one the most important results in the whole story of particle physics. A review of the aspects of the long path, starting from the speculative introduction of the Brout–Englert–Higgs mechanism, continuing with the long search to detect the Higgs particle, and arriving to the discovery is given. The first measurements of the properties are described, their implications are discussed and the future prospects are given.

The LHCb detector is a forward spectrometer at the Large Hadron Collider (LHC) at CERN. The experiment is designed for precision measurements of CP violation and rare decays of beauty and charm hadrons. In this paper the performance of the various LHCb sub-detectors and the trigger system are described, using data taken from 2010 to 2012. It is shown that the design criteria of the experiment have been met. The excellent performance of the detector has allowed the LHCb collaboration to publish a wide range of physics results, demonstrating LHCb's unique role, both as a heavy flavour experiment and as a general purpose detector in the forward region.

A model is presented where the Higgs mechanism of the Standard Model is deduced from the alignment of a strongly correlated fermion system in an internal space with A₄ symmetry. The ground state is constructed and its energy calculated. Finally, it is claimed that the model may be derived from a field theory in 6 + 1 dimensions.

We introduce a novel approach to estimate the thermodynamic pressure from heavy-ion collisions based on recently measured higher-order moments of particle multiplicities by the STAR experiment. We start with fitting the experimental results in the most-central collisions. Then, we integrate them back to lower ones. For example, we find that the first-order moment, the mean multiplicity, is exactly reproduced from the integral of variance, the second-order moment. Therefore, the zeroth-order moment, the thermodynamic pressure, can be estimated from the integral of the mean multiplicity. The possible comparison between such a kind of pressure (deduced from the integral of particle multiplicity) and the lattice pressure and the relating of Bjorken energy density to the lattice energy density are depending on lattice QCD at finite baryon chemical potential and first-principle estimation of the formation time of the quark–gluon plasma (QGP).

We study the Langevin equation with both a white noise and a colored noise. We construct the Lagrangian as well as the Hamiltonian for the generalized Langevin equation which leads naturally to a path integral description from first principles. This derivation clarifies the meaning of the additional fields introduced by Martin, Siggia and Rose in their functional formalism. We show that the transition amplitude, in this case, is the generating functional for correlation functions. We work out explicitly the correlation functions for the Markovian process of the Brownian motion of a free particle as well as for that of the non-Markovian process of the Brownian motion of a harmonic oscillator (Uhlenbeck–Ornstein model). The path integral description also leads to a simple derivation of the Fokker–Planck equation for the generalized Langevin equation.

In Schwinger effect, quantum vacuum instability under the influence of an electric field leads to decay of vacuum into pairs of charged particles. We consider the entanglement of pair produced particles. We will show that the measure of entanglement depends on the geometry of space–time. Using the Schwinger pair production in curved space–time, dS₂ and AdS₂, we propose and demonstrate that the electric field can generate entanglement. In dS₂ space–time, we study entanglement for scalar particles with zero spin in the absence and presence of a constant electric field. We show that the entanglement entropy depends on the choice of the α-vacua. But, for some values of the related parameters (mass, charge, scalar curvature, electric field), the entanglement entropy is independent of α. Also, we consider the generation of entanglement in the presence of a constant electric field for anti-de Sitter space–time. We will show that the positive (negative) curvature of space–time upgrades (degrades) the generated entanglement.

In this paper we will analyze the anti-BRST symmetries of Bagger–Lambert–Gustavsson (BLG) theory in presence of a boundary. We will analyze these symmetries in both linear and nonlinear gauges. We will also derive the finite field version of the anti-BRST transformations for the BLG theory in presence of a boundary. These finite field transformations will be used to relate generating functional in linear gauge to the generating functional in the nonlinear gauge.

We investigate whether inclusion of dimension 6 terms in the Standard Model Lagrangian may cause the unification of the coupling constants at a scale comprised between 10¹⁴ and 10¹⁷ GeV. Particular choice of the dimension 6 couplings is motivated by the spectral action. Given the theoretical and phenomenological constraints, as well as recent data on the Higgs mass, we find that the unification is indeed possible, with a lower unification scale slightly favored.

Topologically massive Yang–Mills theory is studied in the framework of geometric quantization. Since this theory has a mass gap proportional to the topological mass m, Yang–Mills contribution decays exponentially at very large distances compared to 1/m, leaving a pure Chern–Simons theory with level number k. In this paper, the near Chern–Simons limit is studied where the distance is large enough to give an almost topological theory, with a small contribution from the Yang–Mills term. It is shown that this almost topological theory consists of two copies of Chern–Simons with level number k/2, very similar to the Chern–Simons splitting of topologically massive AdS gravity. Also, gauge invariance of these half-Chern–Simons theories is discussed. As m approaches to infinity, the split parts add up to give the original Chern–Simons term with level k. Reduction of the phase space is discussed in this limit. Finally, a relation between the observables of topologically massive Yang–Mills theory and Chern–Simons theory is shown. One of the two split Chern–Simons pieces is shown to be associated with Wilson loops while the other with 't Hooft loops. This allows one to use skein relations to calculate topologically massive Yang–Mills theory observables in the near Chern–Simons limit.

We investigate the analytical method in studying the holographic superfluid model which is described by Maxwell field minimally coupling to a charged scalar field in a fixed AdS black hole background. We propose a method that enables us to find exact value of coefficient in the solution and thus obtain higher-order expansion of the associated Landau free energy of the holographic superfluid with flow. We determine the critical value of superfluid velocity at the tricritical point of holographic superfluid and compare it with the numerical value.