International Journal of Modern Physics A

In this review, we present a derivation of the on-shell renormalization conditions for scalar and fermionic fields in theories with and without parity conservation. We also discuss the specifics of Majorana fermions. Our approach only assumes a canonical form for the renormalized propagators and exploits the fact that the inverse propagators are nonsingular in $𝜀=p^2-m_n^2$, where $p$ is the external four-momentum and $m_n$ is a pole mass. In this way, we obtain full agreement with commonly used on-shell conditions. We also discuss how they are implemented in renormalization.

We review the recent progress on the calculations on the inclusive forward hadron production within the saturation formalism. After introducing the concept of perturbative parton saturation and nonlinear evolution we discuss the formalism for the forward hadron production at high energy in the leading and next-to-leading order. Numerical results are presented and compared with the experimental data on forward hadron production in $dA$ and $pA$. We discuss the problem of the negativity of the NLO cross-section at high transverse momenta, study its origin in detail and present possible improvements which include the corrected kinematics and the suitable choice of the rapidity cutoff.

We give a short overview of Newton–Cartan geometry and gravity including its matter couplings. We also present results on a new non-relativistic gravity model in three spacetime dimensions, called extended Bargmann gravity, and show that this model has matter couplings that differ from those of Newton–Cartan gravity.

In this paper, we study the false vacuum decay of a single scalar field $\varphi$ coupled to gravity described by the Coleman–de Luccia (CdL) instanton. We show that it is possible to numerically calculate the bounce factor, which is related to the CdL tunneling rate, without using the thin-wall approximation. In this paper, we consider $1/cosh(\varphi )$- and $cos(\varphi )$-type potentials as examples, which have cosmological and phenomenological applications. Especially, in the $cos(\varphi )$-type potential, we show that the range of values in which axion decay constant can take is restricted by the form of the periodic potential if the CdL tunneling occurs.

We present a detailed analysis and phenomenological consequences of neutrino mass matrix, $M_{\nu }$, with one-zero texture in the flavor basis where the active neutrino sector is extended by one sterile neutrino (3+1 case). In particular, our aim is to explore behavior of the sterile mixing parameters in detail when one of the elements of the neutrino mass matrix goes to zero. To study this, we consider two distinct mass spectrum of the active neutrinos: (i) completely hierarchical mass spectrum with a vanishing neutrino mass and (ii) completely quasidegenerate mass spectrum. In 3+1 scenario, the low energy neutrino mass matrix, $M_{\nu }$, is a $4\times 4$ matrix and has 10 independent elements. Thus it can have 10 possible one-zero textures. From the earlier studies it can be inferred that, if one assumes one vanishing neutrino mass, then only seven of these $M_{\nu }$ are phenomenologically allowed by the current neutrino oscillation data. On the other hand, if the neutrinos are quasidegenerate then there are eight phenomenologically viable one-zero textures. In this paper, we study the correlations between the sterile mixing parameters for each of these allowed textures for both mass spectrum and also their implications on the effective Majorana mass.

It was suggested by dimensional analysis that there exists a limit called the Planck energy scale coming close to which the gravitational effects of physical processes would inflate and struggle for equal rights so as to spoil the validity of pure nongravitational physical theories that governed well below the Planck energy. Near the Planck scale, the Planck charges, Planck currents, or Planck parameters can be defined and assigned to physical quantities such as the single particle electric charge and magnetic charge as the ceiling value obeyed by the low energy ordinary physics. The Dirac electric-magnetic charge quantization relation as one form of electric-magnetic duality dictates that, the present low value electric charge corresponds to a huge magnetic charge value already passed the Planck limit so as to render theories of magnetic monopoles into the strong coupling regime, and vice versa, that small and tractable magnetic charge values correspond to huge electric charge values. It suggests that for theoretic models in which the renormalization group equation provides rapid growth for the running electric coupling constant, it is easier for the dual magnetic monopoles to emerge at lower energy scales. Allowing charges to vary with the Dirac electric-magnetic charge quantization relation while keeping values under the Planck limit informs that the magnetic charge value drops below the Planck ceiling value into the manageable region when the electric coupling constant grows to one fourth at a model dependent energy scale, and continues dropping toward half the value of the Planck magnetic charge as the electric coupling constant continues growing at the model dependent rate toward one near Planck energy scale.

In this paper, we reformulate topological string theory using supermanifolds and supermoduli spaces, following the approach worked out by Witten (Superstring perturbation theory revisited, arXiv:1209.5461). We intend to make the construction geometrical in nature, by using supergeometry techniques extensively. The goal is to establish the foundation of studying topological string amplitudes in terms of integration over appropriate supermoduli spaces.

The shape of the transverse momentum $(p_T)$ distribution of primary charged particles in minimum bias (nonsingle-diffractive) p–Pb collisions at $\sqrt{s_{NN}}=5.02\mathrm{\text{TeV}}$ is studied in the pseudorapidity regions: $\left|\eta \right|<0.3$, $0.3<\eta <0.8$ and $0.8<\eta <1.3$ and in the transverse momentum range $0.5<p_T<20\mathrm{\text{GeV}}/c$ using simulated data produced with the HIJING 1.0 code. These are compared with the ALICE data measured by the ALICE detector at the LHC. In the model, the central and forward $\eta$-regions differ more than in the ALICE data and due to this fact HIJING 1.0 cannot describe well the high $p_T$ region in the $p_T$ distributions. The comparison of results from simulation implies that the HIJING 1.0 considered narrower pseudorapidity distribution for the charged particles than it is in the ALICE data. It cannot take into account satisfactorily leading effect due to the asymmetric p–Pb fragmentation.

We analyze the constraints for a system of antiself-dual Yang–Mills (ASDYM) equations by means of the modified Faddeev–Jackiw method in $K$ and $J$ gauges à la Yang. We also establish the Hamiltonian flow for ASDYM system through the hidden BRS invariance in both the gauges. Finally, we remark on the bi-Hamiltonian nature of ASDYM and the compatibility of the symplectic structures therein.

We construct the amplitudes of $\pi \eta$ photoproduction taking into account the effects of the $\pi \eta \text{–}K\bar{K}$ interchannel coupling. The idea of our model is to describe the scalar isovectors as dynamically produced in the final state while the initial stage of the reaction being described in terms of meson exchanges. Meson loops which arise this way include not only pseudoscalars but also vector mesons. These amplitudes are used to calculate the $S$-wave cross-sections and mass distributions in the $\pi \eta$ effective mass region corresponding to the scalar resonances $a_0(980)$ and $a_0(1450)$. The values we obtained for $a_0(980)$ are comparable with predictions of other models while the cross-section for $a_0(1450)$ is about an order of magnitude larger than prediction based on the quark model. We show that the amplitudes with loops containing vector mesons calculated in the on-shell approximation are not suppressed in contrast to amplitudes containing only pseudoscalar loops. We also estimate the cross-sections for the $P$- and $D$-waves in the $\pi \eta$ channel.