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Belinski V.A.,ICRANet
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2017

In the present letter we indicate an extension of the pure gravity inverse scattering integration technique to the case when fermions (introduced on the base of supersymmetry) are present. In this way the integrability technique for simple (N=1) supergravity in two space-time dimensions coupled to the matter fields taking values in the Lie algebra of E8(+8) group is developed. This theory contains matter living only in one Weyl representation of SO(16) and represents the reduction to two dimensions of the three-dimensional simple supergravity constructed in [1]. Our spectral linear problem use superspace and covers the complete set of principal bosonic and fermionic equations of motion. This linear system, as in pure gravity, contains only the first order poles with respect to the spectral parameter. The procedure of constructing the exact super-solitonic solutions is outlined. © 2017 The Author


Mohammadi R.,Institute for Research in Fundamental Sciences | Xue S.-S.,ICRANet | Xue S.-S.,University of Rome La Sapienza
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

It is shown that for the reason of neutrinos being left-handed and their gauge-couplings being parity-violated, linearly polarized photons acquire their circular polarization by interacting with neutrinos. Calculating the ratio of linear and circular polarizations of laser photons interacting with either Dirac or Majorana neutrino beam, we obtain this ratio for the Dirac neutrino case, which is about twice less than the ratio for the Majorana neutrino case. Based on this ratio, we discuss the possibility of using advanced laser facilities and the T2K neutrino experiment to measure the circular polarization of laser beams interacting with neutrino beams in ground laboratories. This could be an additional and useful way to gain some insight into the physics of neutrinos, for instance their Dirac or Majorana nature. © 2014 The Authors.


Belinski V.,ICRANet
AIP Conference Proceedings | Year: 2010

The talk represents a review of the old results and contemporary development on the problem of cosmological singularity. © 2010 American Institute of Physics.


Xue S.-S.,ICRANeT | Xue S.-S.,University of Rome La Sapienza
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

We present a further study of the dynamics of high-dimension fermion operators attributed to the theoretical inconsistency of the fundamental cutoff (quantum gravity) and the parity-violating gauge symmetry of the standard model. Studying the phase transition from a symmetry-breaking phase to a strong-coupling symmetric phase and the β-function behavior in terms of four-fermion coupling strength, we discuss the critical transition point as a ultraviolet-stable fixed point where a quantum field theory preserving the standard model gauge symmetry with composite particles can be realized. The form-factors and masses of composite particles at TeV scales are estimated by extrapolating the solution of renormalization-group equations from the infrared-stable fixed point where the quantum field theory of standard model is realized and its phenomenology including Higgs mass has been experimentally determined. We discuss the probability of composite-particle formation and decay that could be experimentally verified in the LHC by measuring the invariant mass of relevant final states and their peculiar kinetic distributions. © 2014 The Author. Published by Elsevier B.V.


Belinski V.A.,ICRANet
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

The integrable ansatz for pure Einstein gravity is extended to supergravity, and the procedure for constructing exact supergravitational solitonic solutions is described. © 2015 American Physical Society.


Xue S.-S.,ICRANeT | Xue S.-S.,University of Rome La Sapienza
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

In the fermion content and gauge symmetry of the standard model (SM), we study the four-fermion operators in the torsion-free Einstein-Cartan theory. The collider signatures of irrelevant operators are suppressed by the high-energy cutoff (torsion-field mass) Λ, and cannot be experimentally accessible at TeV scales. Whereas the dynamics of relevant operators accounts for (i) the SM symmetry-breaking in the domain of infrared-stable fixed point with the energy scale v≈239.5GeV and (ii) composite Dirac particles restoring the SM symmetry in the domain of ultraviolet-stable fixed point with the energy scale E≳5 TeV. To search for the resonant phenomena of composite Dirac particles with peculiar kinematic distributions in final states, we discuss possible high-energy processes: multi-jets and dilepton Drell-Yan process in LHC pp collisions, the resonant cross-section in e-e+ collisions annihilating to hadrons and deep inelastic lepton-hadron e-p scatterings. To search for the nonresonant phenomena due to the form-factor of Higgs boson, we calculate the variation of Higgs-boson production and decay rate with the CM energy in LHC. We also present the discussions on four-fermion operators in the lepton sector and the mass-squared differences for neutrino oscillations in short baseline experiments. © 2015 The Author.


Xue S.-S.,ICRANeT | Xue S.-S.,University of Rome La Sapienza
Nuclear Physics B | Year: 2015

With a basic varying space-time cutoff ℓ~, we study a regularized and quantized Einstein-Cartan gravitational field theory and its domains of ultraviolet-unstable fixed point gir≳0 and ultraviolet-stable fixed point guv≈4/3 of the gravitational gauge coupling g=(4/3)G/GNewton. Because the fundamental operators of quantum gravitational field theory are dimension-2 area operators, the cosmological constant is inversely proportional to the squared correlation length Λ∝ξ-2. The correlation length ξ characterizes an infrared size of a causally correlate patch of the universe. The cosmological constant Λ and the gravitational constant G are related by a generalized Bianchi identity. As the basic space-time cutoff ℓ~ decreases and approaches to the Planck length ℓpl, the universe undergoes inflation in the domain of the ultraviolet-unstable fixed point gir, then evolves to the low-redshift universe in the domain of ultraviolet-stable fixed point guv. We give the quantitative description of the low-redshift universe in the scaling-invariant domain of the ultraviolet-stable fixed point guv, and its deviation from the ΛCDM can be examined by low-redshift (z ≲1) cosmological observations, such as supernova Type Ia. © 2015 The Author.


Xue S.-S.,ICRANeT | Xue S.-S.,University of Rome La Sapienza
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

By introducing diffeomorphism and local Lorentz gauge invariant holonomy fields, we study in the recent article [S.-S. Xue, Phys. Rev. D 82 (2010) 064039] the quantum Einstein-Cartan gravity in the framework of Regge calculus. On the basis of strong coupling expansion, mean-field approximation and dynamical equations satisfied by holonomy fields, we present in this Letter calculations and discussions to show the phase structure of the quantum Einstein-Cartan gravity, (i) the order phase: long-range condensations of holonomy fields in strong gauge couplings; (ii) the disorder phase: short-range fluctuations of holonomy fields in weak gauge couplings. According to the competition of the activation energy of holonomy fields and their entropy, we give a simple estimate of the possible ultra-violet critical point and correlation length for the second-order phase transition from the order phase to disorder one. At this critical point, we discuss whether the continuum field theory of quantum Einstein-Cartan gravity can be possibly approached when the macroscopic correlation length of holonomy field condensations is much larger than the Planck length. © 2012 Elsevier B.V.


Raffaelli B.,ICRANet
General Relativity and Gravitation | Year: 2016

We examine in a semiclassical framework the deflection function of strong gravitational lensing, for static and spherically symmetric black holes, endowed with a photon sphere. From a first-order WKB analysis near the maximum of the Regge-Wheeler potential, we extract the real phase shifts from the S-matrix elements and then we derive the associated semiclassical deflection function, characterized by a logarithmic divergent behavior. More precisely, using the complex angular momentum techniques, we show that the Regge poles and the associated greybody factor residues, for a massless scalar field theory, from which one can recover the black hole quasinormal complex frequencies as well as the fluctuations of the high energy absorption cross section, play naturally the role of critical parameters in the divergent behavior of the semiclassical deflection function. For very high frequencies, we finally recover the logarithmic part of the classical strong deflection limit, which clarifies analytically the fundamental link between quasinormal modes and strong gravitational lensing, suggested in recent works. © 2016, Springer Science+Business Media New York.


Xue S.-S.,ICRANeT | Xue S.-S.,University of Rome La Sapienza
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

The recent ATLAS and CMS experiments show the first observations of a new particle in the search for the Standard Model Higgs boson at the LHC. We revisit the scenario that high-dimensional operators of fermions must be present due to the theoretical inconsistency of the fundamental cutoff (quantum gravity) with the parity-violating gauge symmetry of the Standard Model. Studying the four-fermion interaction of the third quark family, we show that at an intermediate energy threshold E≈4.27×103GeV for the four-fermion coupling being larger than a critical value, the spontaneous symmetry-breaking phase transits to the strong-coupling symmetric phase where composite Dirac fermions form fully preserving the chiral gauge symmetry of the Standard Model and the parity-symmetry is restored. Under this circumstance, we perform the standard analysis of renormalization-group equations of the Standard Model in the spontaneous symmetry-breaking phase. As a result, the Higgs boson mass mH≈126.7GeV and top-quark mass mt≈172.7GeV are obtained without drastically fine-tuning the four-fermion coupling. © 2013 Elsevier B.V.

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