International Journal of Modern Physics A

This report will review the Higgs boson properties: the mass, the total width and the couplings to fermions and bosons. The measurements have been performed with the data collected in 2011 and 2012 at the LHC accelerator at CERN by the ATLAS and CMS experiments. Theoretical frameworks to search for new physics are also introduced and discussed.

We present the unique properties of oscillatory modes of $N_{\mathrm{\text{fl}}}=3$ light quarks — $u$, $d$, $s$ — using the $SU(2N_{\mathrm{\text{fl}}}=6)\times SO3(\overrightarrow{L})$ broken symmetry classification. $\overrightarrow{L}={\sum }_{n=1}^{N_{\mathrm{\text{fl}}}}{\overrightarrow{L}}_n$ stands for the space rotation group generated by the sum of the three individual angular momenta of quarks in their c.m. system. The baryonic multiplets are shown to emerge from the picture of oscillating quarks in three space dimensions in the center-of-mass system of the baryons. All oscillatory modes are fully relativistic with a finite number of oscillators and this is forming the unique harmonic oscillator with these properties. The density of states as a function of mass-square is calculated. This estimate is of relevance for the accounting of the missing states of unobserved hadrons, as the here estimated baryonic multiplets include both the observed and the unobserved (or “missing”) hadrons. The estimate is conceptually different from Hagedorn’s model and is based on field theory of QCD.

In this work, we point out that the apparent diphoton excess initially presented by the ATLAS and CMS collaborations could have originated from a radion in the bulk Higgs scenario within a warped extra dimension. In this scenario, the couplings of the radion to massive gauge bosons are suppressed, allowing it to evade existing searches. In the presence of mixing with the Higgs, due to the strong constraints from diboson searches, only points near what we denominate the alignment region were able to explain the diphoton signal and evade other experimental constraints. In light of the new measurements presented at ICHEP 2016 by both LHC collaborations, which do not confirm the initial diphoton excess, we study the current and future collider constraints on a radion within the bulk-Higgs scenario. We find that searches in the diphoton channel provide the most powerful probe of this scenario and already exclude large regions of parameter space, particularly for smaller warp factors. The radion has a sizeable branching ratio into top pairs and this channel may also give competitive constraints in the future. Finally, di-Higgs searches can provide a complementary probe in the case of nonzero radion-Higgs mixing but strong alignment.

The possibility of heavy neutralino dark matter (DM) in the gravity-mediation mechanism is explored. The appearance of the heavy lightest supersymmetric particle is seemingly suggested by Large Hadron Collider runs, which have not provided evidence of superparticles around the TeV region. On the basis of the so-called WIMPZILLA scenario, it is understood that the nonthermally produced DM has the larger mass than the reheating temperature. Hence, the expected DM mass should be more than 10⁹ GeV so that thermal leptogenesis successfully occurs. In this paper, we first examine the generation of the Higgsino mass parameter $(\mu )$ in the context of gravity mediation, postulating that the resolution of the strong CP problem should be the criterion for arriving at a valid hypothesis for heavy neutralino DM. Accordingly, we address how the Peccei–Quinn (PQ) symmetry could influence dynamical supersymmetry breaking (DSB) models. It is found that as long as ${\mathrm{\Lambda }}_{\mathrm{\text{SUSY}}}$ (the SUSY-breaking scale) approximately coincides with ${\mathrm{\Lambda }}_{\mathrm{\text{PQ}}}$ (the PQ-breaking scale), no DSB models can naturally account for the existence of the heavy neutralino DM, based upon the supersymmetric Dine–Fischler–Srednicki–Zhitinitski (DFSZ)-like mechanism. Thus, we attempt to construct a new model wherein hierarchical SUSY breakings occur. For this purpose, we propose gauge coupling unification in the hidden-sector dynamics at some high-energy scale, and we show that such a class of models can achieve ${\mathrm{\Lambda }}_{\mathrm{\text{SUSY}}}\gg {\mathrm{\Lambda }}_{\mathrm{\text{PQ}}}$ through renormalization flow. As a consequence, the nonthermal neutralino, practically the wino-like one in our model, is shown to be a rather natural and viable DM candidate. Moreover, we argue that on the basis of Kac–Moody algebra, multiple breakdowns of supersymmetry may entail unified gauge dynamics. We also present a possible unified model. Finally, the heavy wino-like neutralino may be a DM candidate that will favor future direct DM detection experiments, mainly because its scattering on nuclei well conserves isospin symmetry.

We elucidate the mechanism of enhancement of the ${\bar{\nu }}_{\mu }\to {\bar{\nu }}_s$ transitions at small mixing angles of Earth-core-crossing neutrinos, which is at the basis of the recent result of the IceCube experiment on atmospheric muon antineutrino oscillations into sterile antineutrino.

In this paper, we establish the analysis of noncommutative Yukawa theory, encompassing neutral and charged scalar fields. We approach the analysis by considering carefully the derivation of the respective effective actions. Hence, based on the obtained results, we compute the one-loop contributions to the neutral and charged scalar field self-energy, as well as to the Chern–Simons polarization tensor. In order to properly define the behavior of the quantum fields, the known UV/IR mixing due to radiative corrections is analyzed in the one-loop physical dispersion relation of the scalar and gauge fields.

The complete spectrum of $c\bar{b}$ states is obtained in a phenomenological nonrelativistic quark model (NRQM), which consists of a confinement potential and one gluon exchange potential (OGEP) as effective quark–antiquark potential. We make predictions for the radiative decay (E1 and M1) widths and weak decay widths of $c\bar{b}$ states in the framework of NRQM formalism.

In this paper, we calculate the strong decays of $2^{+}$ heavy-light states, namely, the charmed $D_2^{\ast }{(2460)}^0$ meson and the charm-strange $D_{s2}^{\ast }{(2573)}^{+}$ meson. The method we adopt is the reduction formula, PCAC relation and low energy theorem, following which, the transition amplitudes are calculated. The wave functions of the heavy mesons involved are achieved by solving the instantaneous Bethe–Salpeter equation. As the OZI-allowed two-body strong decays give the dominant contribution, they can be used to estimate the total widths of mesons. Our results are: $\mathrm{\Gamma }[D_2^{\ast }{(2460)}^0]=51.3\mathrm{\text{MeV}}$ and $\mathrm{\Gamma }[D_{s2}^{\ast }{(2573)}^{+}]=19.6\mathrm{\text{MeV}}$. The ratios of branching ratios of two main channels are $\mathrm{\text{Br}}[D_2^{\ast }{(2460)}^0\to D^{+}{\pi }^{-}]/\mathrm{\text{Br}}[D_2^{\ast }{(2460)}^0\to D^{\ast +}{\pi }^{-}]=2.13$ and $\mathrm{\text{Br}}[D_{s2}^{\ast }{(2573)}^{+}\to D^{\ast 0}{K}^{+}]/\mathrm{\text{Br}}[D_{s2}^{\ast }{(2573)}^{+}\to D^0{K}^{+}]=0.08$, respectively.

In the context of the covariant symmetry breaking in gravity, we study the quantum aspect of Chamseddine–Mukhanov model by making use of path integral method. Utilizing one of the gauge fixing constraints, we remove the specific ghost degree of freedom. In continuation, we define an auxiliary effective action. Introducing an auxiliary field, we will have a new dynamic field in addition to the fundamental field.

In this paper, we study a nonlocal Nambu–Jona-Lasinio (nNJL) model with a Gaussian regulator in presence of a uniform magnetic field. We take a mixed approach to the incorporation of temperature in the model, and consider aspects of both real and imaginary time formalisms. We include confinement in the model through the quasiparticle interpretation of the poles of the propagator. By working in the real time formalism and computing the spectral density function, we find that the effect of the magnetic field on the poles of the propagator can be entirely absorbed within the mean field value of the scalar field. The analytic structure of our propagator is then preserved in the weak magnetic field limit. The effect of the magnetic field in the deconfinement phase transition is then studied. It is found that, like with chiral symmetry restoration, magnetic catalysis occurs for the deconfinement phase transition. It is also found that the magnetic field enhances the thermodynamical instability of the system. We work in the weak field limit, i.e. $(eB)<5m_{\pi }^2$. At this level there is no splitting of the critical temperatures for chiral and deconfinement phase transitions.