L. V. Laperashvili

Cosmological constant in SUGRA models and the multiple-point principle

An attempt is made to explain the tiny order of magnitude of the cosmological constant in a model involvingt he following ingredients: supersymmetry breaking in N = 1 supergravity and the multiple-point principle. We demonstrate the viability of this scenario in the minimal SUGRA model.

Dirac Relation and Renormalization Group Equations for Electric and Magnetic Fine Structure Constants

The quantum field theory describing electric and magnetic charges and revealing a dual symmetry was developed in the Zwanziger formalism. The renormalization group (RG) equations for both fine structure constants — electric α and magnetic — were obtained. It was shown that the Dirac relation is valid for the renormalized α and at the arbitrary scale, but these RG equations can be considered perturbatively only in the small region: 0.25≲α, with given by the Dirac relation: .

Monopoles near the Planck scale and unification

Considering our (3+1)-dimensional space–time as, in some way, discrete or lattice with a parameter a = λP, where λP is the Planck length, we have investigated the additional contributions of lattice artifact monopoles to beta functions of the renormalization group equations for the running fine structure constants αi(μ) (i = 1,2,3 correspond to the U(1), SU(2) and SU(3) gauge groups of the Standard Model) in the Family Replicated Gauge Group Model (FRGGM) which is an extension of the Standard Model at high energies. It was shown that monopoles have Nfam times smaller magnetic charge in FRGGM than in SM (Nfam is the number of families in FRGGM). We have estimated also the enlargement of a number of fermions in FRGGM leading to the suppression of the asymptotic freedom in the non-Abelian theory. We have shown that, in contrast to the case of anti-GUT when the FRGGM undergoes the breakdown at μ = μG ~ 1018GeV, we have the possibility of unification if the FRGGM-breakdown occurs at μG ~ 1014GeV. By numerical calculations we obtained an example of the unification of all gauge interactions (including gravity) at the scale μGUT ≈ 1018.4GeV. We discussed the possibility of [SU(5)]3 or [SO(10)]3 (SUSY or not SUSY) unifications.

Graviweak Unification, Invisible Universe and Dark Energy

We consider a graviweak unification model with the assumption of the existence of a hidden (invisible) sector of our Universe, parallel to the visible world. This Hidden World (HW) is assumed to be a Mirror World (MW) with broken mirror parity. We start with a diffeomorphism invariant theory of a gauge field valued in a Lie algebra , which is broken spontaneously to the direct sum of the space–time Lorentz algebra and the Yang–Mills algebra: — in the ordinary world, and — in the hidden world. Using an extension of the Plebanski action for general relativity, we recover the actions for gravity, SU(2) Yang–Mills and Higgs fields in both (visible and invisible) sectors of the Universe, and also the total action. After symmetry breaking, all physical constants, including the Newtons constants, cosmological constants, Yang–Mills couplings, and other parameters, are determined by a single parameter g present in the initial action, and by the Higgs VEVs. The dark energy problem of this model predicts a too large supersymmetric breaking scale (MSUSY ~1010GeV), which is not within the reach of the LHC experiments.

NEW BOUND STATES OF HEAVY QUARKS AT LHC AND TEVATRON

The present paper is based on the assumption that heavy quarks bound states exist in the Standard Model (SM). Considering New Bound States (NBS) of topanti-top quarks (named T-balls) we have shown that: 1) there exists the scalar 1S–bound state of 6t + 6t̄; 2) the forces which bind the top-quarks are very strong and almost completely compensate the mass of the twelve top-anti-top-quarks in the scalar NBS; 3) such strong forces are produced by the Higgs-top-quarks interaction with a large value of the top-quark Yukawa coupling constant gt ≃ 1. Theory also predicts the existence of the NBS 6t + 5t̄, which is a color triplet and a fermion similar to the t-quark of the fourth generation. We have also considered the “bquark-replaced” NBS. We have estimated the masses of the lightest fermionic NBS: MNBS & 300 GeV, and discussed the larger masses of T-balls. Searching for heavy quarks bound states at the Tevatron and LHC is discussed. crdas@cftp.ist.utl.pt c.froggatt@physics.gla.ac.uk laper@itep.ru hbech@nbi.dk

Monopoles and family-replicated unification

The present theory is based on the assumption that, at very small (Planck scale) distances our spacetime is discrete, and this discreteness influences the Planck scale physics. Considering our (3+1)-dimensional spacetime as a regular hypercubic lattice with a parameter a=λPl, where λPl is the Planck length, we have investigated a role of lattice artifact monopoles, which is essential near the Planck scale if the family-replicated gauge group model (FRGGM) is an extension of the Standard Model (SM) at high energies. It was shown that monopoles have N times smaller magnetic charge in the FRGGM than in the SM (N is the number of families in the FRGGM). These monopoles can give an additional contribution to β functions of the renormalization-group equations for the running fine structure constants αi(μ) (i=1, 2, 3 correspond to the U(1), SU(2), and SU(3) gauge groups of the SM). We have used the Dirac relation for renormalized electric and magnetic charges. Also, we have estimated the enlargement of a number of fermions in the FRGGM leading to the suppression of the asymptotic freedom in the non-Abelian theory. The different role of monopoles in the vicinity of the Planck scale gives rise either to anti-GUT or to the new possibility of unification of gauge interactions (including gravity) at the scale μGUT≈1018.4 GeV. We discussed the possibility of the [SU(5)]3 SUSY or [SO(10)]3 SUSY unifications.

Flipped SU(5), seesaw scale physics and degenerate vacua

We investigate the requirement of the existence of two degenerate vacua of the effective potential as a function of the Weinberg–Salam Higgs scalar field norm, as suggested by the multiple point principle, in an extension of the Standard Model including seesaw scale physics. Results are presented from an investigation of an extension of the Standard Model to the gauge symmetry group SU(3)C×SU(2)L×U(1)′×Ũ(1), where U(1)′ and Ũ(1) originate at the seesaw scale MSS, when heavy (right-handed) neutrinos appear. The consequent unification of the group SU(3)C×SU(2)L×U(1)′ into the flipped SU(5) at the GUT scale leads to the group SU(5)×Ũ(1). We assume the position of the second minimum of the effective potential coincides with the fundamental scale, here taken to be the GUT scale. We solve the renormalization group equations in the one-loop approximation and obtain a top-quark mass of 171±3 GeV and a Higgs mass of 129±4 GeV, in the case when the Yukawa couplings of the neutrinos are less than half that of the top quark at the GUT scale.

Phase transition in gauge theories and multiple-point model

The phase transition in the regularized U(1) gauge theory is investigated by using the dual Abelian Higgs model of scalar monopoles. The corresponding-renormalization-group-improved effective potential, analogous to the Coleman-Weinberg one, is considered in the two-loop approximation for β functions, and the phase-transition (critical) dual and nondual couplings are calculated in the U(1) gauge theory. It is shown that the critical value of the renormalized electric fine-structure constant,αcrit≈0.208, obtained in this study agrees with the lattice result for compact QED: αcritlat≈0.20±0.015. This result and the behavior of α in the vicinity of the phase-transition point are compared with the multiple-point-model prediction for the values of α near the Planck scale. Such a comparison is very encouraging for the multiple point model assuming the existence of the multiple critical point at the Planck scale.

Top Yukawa New Strong Sector, Higgs Decay and Production

We call attention to the fact that the top-Yukawa-coupling gt being of order unity a priori opens up the possibility for there existing a new sector of strongly i nteracting particles. That is to say that you may have phenomena such as bound states among the particl es involved in these relatively strong interacions caused by the Yukawa coupling gt , much analogous to QCD. That is to say: top quarks and Higgses should form possible resonances and s tro g binding. Really one should rather ask for whether g2 t /2/(2π) is large or small compared to unity, and thus it seems at first n ot of order unity, but if we correct by a factor 12 for considerin g a bound state of 12 constituents, we get a number of order unity, and a strong sector is expected ! After the Korfu meeting a new diphoton resonace of mass 750 GeV were found in ATLAS and CMS, which could potentially be a bound state of 6 top + 6 anti top binding strongly, precisely b cause the top-Yukawa coupling is “large”.