International Journal of Modern Physics A

In 2002, the ATHENA experiment was the first to produce large amounts of antihydrogen atoms at the CERN Antiproton Decelerator (AD). In this review article, we collect and discuss all the relevant results of the experiment: antiproton and positron cooling and their recombination dynamics in the nested Penning trap, the methods used to unambiguously identify the antiatoms as well as the protonium background, the dependence of the antihydrogen formation on mixing time and temperature. An attempt to interpret the results in terms of the two-body and three-body formation reactions, taking into account the complicated nested-trap dynamics, is also made. The relevance of the ATHENA results on future experiments is discussed, together with a short overview of the current antimatter physics at the AD.

The group theoretical description of the three-particle problem provides successful techniques for the solution of different questions. We present here a review of this approach.

In Standard Model, CP violation arises from an irreducible complex phase in the quark mixing matrix, now under the name Cabibbo–Kobayashi–Maskawa matrix. This description has shown remarkable overall agreement with various experimental measurements. In this review, we discuss recent experimental data and theoretical developments on three quantities of CKM matrix that are most uncertain: the V_ub, including its magnitude and the phase γ in standard parametrization, and the mixing phase β_s.

The conventional baryogenesis mechanism is based on the one Higgs doublet within the Standard Model, at the electroweak scale T ~ 100 GeV. In this model, the strong first-order phase transition due to the spontaneous symmetry breaking imposes the following condition on the mass of the Higgs field: m_H ≲ 40 GeV, which is contrary to the recently observed value m_H ≃ 126 GeV. In this paper, we propose a baryogenesis mechanism within a two-Higgs-doublet model in which the phase transition occurs in one stage. This model is consistent with the observed mass of the Higgs. We obtain the true vacuum bubble wall velocity and thickness in this model. Then, we use nonlocal baryogenesis mechanism in which the interaction of fermions with the boundary of the expanding bubbles leads to CP violation and sphaleron mediated baryogenesis.

In the backdrop of generalized Randall–Sundrum braneworld scenario, we look for the possible origin of an effective four-dimensional cosmological constant (Ω_vis) on the visible three-brane due to the effects of bulk curvature and the modulus field that can either be a constant or a time-dependent quantity. In case of constant modulus field, the induced Ω_vis leads to an exponentially expanding universe and the presence of vacuum energy densities on either of the three-branes as well as a nonvanishing bulk curvature are essential to generate an effective Ω_vis. The Hubble constant turns out to be equal to the visible brane cosmological constant which agrees with the present result. In an alternative scenario, a time-dependent modulus field is found to be capable of decelerating the universe. The Hubble parameter, in this case is determined for a slowly time-varying modulus field.

In the probe limit, we study the holographic p-wave phase transition in the Gauss–Bonnet gravity via numerical and analytical methods. Concretely, we study the influences of the external magnetic field on the Maxwell complex vector model in the five-dimensional Gauss–Bonnet–AdS black hole and soliton backgrounds, respectively. For the two backgrounds, the results show that the magnetic field enhances the superconductor phase transition in the case of the lowest Landau level, while the increasing Gauss–Bonnet parameter always hinders the vector condensate. Moreover, the Maxwell complex vector model is a generalization of the SU(2) Yang–Mills model all the time. In addition, the analytical results backup the numerical results. Furthermore, this model might provide a holographic realization for the QCD vacuum instability.

Surface tension of quark–gluon plasma (QGP) evolution with one-loop correction in the mean-field potential is studied. First, with the correction, the stable QGP droplet size decreases. Then, the value of surface tension is found to be improved and it approaches to the lattice value of surface tension . Moreover, the ratio of the surface tension to the cube of the critical temperature is found to increase the value in comparison to earlier studies without correction factor [R. Ramanathan, K. K. Gupta, A. K. Jha and S. S. Singh, Pram. J. Phys. 68, 757 (2007)].

Leptogenesis is the most favorable mechanism for generating the observed baryon asymmetry of the universe (BAU) which implies CP violation in the high energy scale. The low energy leptonic CP violation is expected to be observed in the neutrino oscillations and 0ν2β decay experiments. Generally, it is not possible to connect both the CP violations. Here we revisit the issue of connecting the two in flavored leptogenesis scenario within the Type I seesaw in the light of recent neutrino oscillation and Planck data. With the recent precise measurements of θ₁₃ and BAU, we are able to find new correlations between the low and high energy CP violating phases when leptogenesis occurs at temperature between 10⁹ to 10¹² GeV and there is no contribution to CP violation from the heavy neutrino sector.

In this paper, we will analyze the consequences of deforming the canonical commutation relations consistent with the existence of a minimum length and a maximum momentum. We first generalize the deformation of first quantized canonical commutation relation to second quantized canonical commutation relation. Thus, we arrive at a modified version of second quantization. A modified Wheeler–DeWitt equation will be constructed by using this deformed second quantized canonical commutation relation. Finally, we demonstrate that in this modified theory the big bang singularity gets naturally avoided.

The technical breakthroughs of multiple detectors developed by Daya Bay and RENO collaborations have gotten great attention. Yet the optimal determination of neutrino mixing parameters from reactor data depends on the statistical method and demands equal attention. We find that a straightforward method using minimal parameters will generally outperform a multi-parameter method by delivering more reliable values with sharper resolution. We review standard confidence levels and statistical penalties for models using extra parameters, and apply those rules to our analysis. We find that the methods used in recent work of the Daya Bay and RENO collaborations have several undesirable properties. The existing work also uses nonstandard measures of significance which we are unable to explain. A central element of the current methods consists of variationally fitting many more parameters than data points. As a result, the experimental resolution of sin²(2θ₁₃) is degraded. The results also become extremely sensitive to certain model parameters that can be adjusted arbitrarily. The number of parameters to include in evaluating significance is an important issue that has generally been overlooked. The measures of significance applied previously would be consistent if and only if all parameters but one were considered to have no physical relevance for the experiment's hypothesis test. Simpler, more transparent methods can improve the determination of the mixing angle θ₁₃ from reactor data, and exploit the advantages from superb hardware technique of the experiments. We anticipate that future experimental analysis will fully exploit those advantages.

We review the construction of the fermionic basis for sinh–Gordon model and investigate numerically the ultraviolet limit of the one-point functions. We then compare the predictions obtained from this formalism against previously established results.

We show that for every qubit of quantum information, there is a well-defined notion of "the amount of energy that carries it," because it is a conserved quantity. This generalizes to larger systems and any conserved quantities: the eigenvalue spectrum of conserved charges has to be preserved while transferring quantum information. It is possible to "apparently" violate these conservations by losing a small fraction of information, but that must invoke a specific process which requires a large scale coherence. We discuss its implication regarding the black hole information paradox.