A First-Quantized Model for Unparticles and Gauge Theories around Conformal Window

We first quantize an action proposed by Casalbuoni and Gomis in 2014 that describes two massless relativistic scalar particles interacting via a conformally invariant potential. The spectrum is a continuum of massive states that may be interpreted as unparticles. We then obtain in a similar way the mass operator for a deformed action in which two terms are introduced that break the conformal symmetry: a mass term and an extra position-dependent coupling constant. A simple Ansatz for the latter leads to a mass operator with linear confinement in terms of an effective string tension σ. The quantized model is confining when σ≠0 and its mass spectrum shows Regge trajectories. We propose a tensionless limit in which highly excited confined states reduce to (gapped) unparticles. Moreover, the low-lying confined bound states become massless in the latter limit as a sign of conformal symmetry restoration and the ratio between their masses and σ stays constant. The originality of our approach is that it applies to both confining and conformal phases via an effective interacting model.

On the Schwarzschild-Anti-de Sitter black hole with an f(R) global monopole

In this work, we follow the recently revisited f(R) theory of gravity for studying the interaction between quantum scalar particles and the gravitational field of a generalized black hole with an f(R) global monopole. This background has a term playing the role of an effective cosmological constant, which permits us to call it as Schwarzschild-Anti-de Sitter (SAdS) black hole with an f(R) global monopole. We examine the separability of the Klein–Gordon equation with a non-minimal coupling and then we discuss both the massless and massive cases for a conformal coupling. We investigate some physical phenomena related to the asymptotic behavior of the radial function, namely, the black hole radiation, the quasibound states, and the wave eigenfunctions.

Computation of gravitational particle production using adiabatic invariants

Analytic and numerical techniques are presented for computing gravitational production of scalar particles in the limit that the inflaton mass is much larger than the Hubble expansion rate at the end of inflation. These techniques rely upon adiabatic invariants and time modeling of a typical inflaton field which has slow and fast time variation components. A faster computation time for numerical integration is achieved via subtraction of slowly varying components that are ultimately exponentially suppressed. The fast oscillatory remnant results in production of scalar particles with a mass larger than the inflationary Hubble expansion rate through a mechanism analogous to perturbative particle scattering. An improved effective Boltzmann collision equation description of this particle production mechanism is developed. This model allows computation of the spectrum using only adiabatic invariants, avoiding the need to explicitly solve the inflaton equations of motion.

General one-loop contributions to the decay H → νl ν̄l γ

General one-loop contributions to the decay amplitudes H → νl ν̄l γ are presented, considering all possible contributions of additional heavy vector gauge bosons, fermions, and charged (and also neutral) scalar particles appearing in the loop diagrams. Moreover, the results can be applied directly when extra neutrinos (apart from three ones in standard model) are taken into account in final states. Analytic results are expressed in terms of Passarino-Veltman scalar functions which can be evaluated numerically using LoopTools. In the standard model framework, these analytical results are generated and cross-checked with previous computations. We find that our results are well consistent with these computations. Within standard model limit, phenomenological results for the decay channels are also studied using the present input parameters at the Large Hadron Collider. Lastly, the calculation is also applied to Two Higgs Doublet Model framework as another example.

One-loop Form Factors for \(H\rightarrow \gamma^*\gamma^*\) in \(R_{\xi}\) Gauge

In this paper, we present general one-loop form factors for \(H\rightarrow \gamma^* \gamma^*\) in \(R_{\xi}\) gauge, considering all cases of two on-shell, one on-shell and two off-shell for final photons. The calculations are performed in standard model and in arbitrary beyond the standard models which charged scalar particles may be exchanged in one-loop diagrams. Analytic results for the form factors are shown in general forms which are expressed in terms of the Passarino-Veltman functions. We also confirm the results in previous computations which are available for the case of two on-shell photons. The \(\xi\)-independent of the result is also discussed. We find that numerical results are good stability with varying \(\xi=0,1\) and $\xi\rightarrow \infty\).

Generation and annihilation of scalar particles due to a curved expanding and contracting space-time.

While a theory calculating a cosmological generation of particles ina case of the expanding space-time is quite developed, we study here a theory of a cosmological generation of particles in a case of a space- time which is expanding and then contracting back. The simplest case of fields studied in this connection is a scalar field. We will show in our paper that the quantum scalar field has delocalized in the conformal time η particle-like modes uⁱⁿ and two localized in the conformal time modes uⁱⁿ and uⁱⁿ for our choosen scale factor C(η). The vacuum for these states | 0, out > defined through massive modes uᵒᵘᵗ and through modes uᵒᵘᵗ and uᵒᵘᵗ is the same as the vacuum | 0, in >. A detector shows that there are no mass particles and no localized states forη → +∞ for non-accelerating case. For η → −∞ a Minkowski space- time is realized, as it is realized also in the out case. The quantum field has delocalized in the conformal time η particle-like modes uᵒᵘᵗ which in the -out region have k-dependent phase shifts with respect to the quantum field delocalized in the conformal time η particle-like modes uⁱⁿ in the -in region. The phase shift of delocalized modes (k-particles) is due to scattering in the gravitational field leading toexpansion and contraction of the space. Thus while in the expansion phase there is present generation of particles, due to nonpresence of particles in η → +∞ conformal time it is clear that in the phase of contraction of the scale factor there is present annihilation of particles from their peak state, where they are occurring from the generationprocess.

Black hole S-matrix for a scalar field

We describe a unitary scattering process, as observed from spatial infinity, of massless scalar particles on an asymptotically flat Schwarzschild black hole background. In order to do so, we split the problem in two different regimes governing the dynamics of the scattering process. The first describes the evolution of the modes in the region away from the horizon and can be analysed in terms of the effective Regge-Wheeler potential. In the near horizon region, where the Regge-Wheeler potential becomes insignificant, the WKB geometric optics approximation of Hawking’s is replaced by the near-horizon gravitational scattering matrix that captures non-perturbative soft graviton exchanges near the horizon. We perform an appropriate matching for the scattering solutions of these two dynamical problems and compute the resulting Bogoliubov relations, that combines both dynamics. This allows us to formulate an S-matrix for the scattering process that is manifestly unitary. We discuss the analogue of the (quasi)-normal modes in this setup and the emergence of gravitational echoes that follow an original burst of radiation as the excited black hole relaxes to equilibrium.

Effects of Linear Central Potential Induced by Lorentz Symmetry Violation framework and Cornell-type Non-electromagnetic Potential on Spin-0 Scalar Particles

The relativistic quantum dynamics of a spin-0 scalar particle under the effects of the violation of Lorentz symmetry in the presence of a non-electromagnetic potential is analyzed. The central potential induced by the Lorentz symmetry violation is a linear electric and constant magnetic field and, analyze the effects on the eigenvalues and the wave function. We see there is a dependence of the linear charge density on the quantum numbers of the system

The electro-weak phase transition at colliders: confronting theoretical uncertainties and complementary channels

We explore and contrast the capabilities of future colliders to probe the nature of the electro-weak phase transition. We focus on the real singlet scalar field extension of the Standard Model, representing the most minimal, yet most elusive, framework that can enable a strong first-order electro-weak phase transition. By taking into account the theoretical uncertainties and employing the powerful complementarity between gauge and Higgs boson pair channels in the searches for new scalar particles, we find that a 100 TeV proton collider has the potential to confirm or falsify a strong first-order transition. Our results hint towards this occurring relatively early in its lifetime. Furthermore, by extrapolating down to 27 TeV, we find that a lower-energy collider may also probe a large fraction of the parameter space, if not all. Such early discoveries would allow for precise measurements of the new phenomena to be obtained at future colliders and would pave the way to definitively verify whether this is indeed the physical remnant of a scalar field that catalyses a strong first-order transition.