Grand unification with local supersymmetry

We study general conditions for obtaining spontaneous breaking of local supersymmetry in N = 1 supergravity coupled to supersymmetric matter. We consider in particular the coupling of N = 1 supergravity to grand unified theories like SU(5) and study the conditions which must be met in order to obtain a realistic model. Specific models are built in which local supersymmetry is broken at a scale √M_Wm_p ～ 10¹⁰ GeV. This breaking of supersymmetry is only detected at low energies through soft terms breaking explicitly the global supersymmetry. These soft terms (scalar masses, gaugino masses and trilinear scalar couplings) are renormalized at low energies according to the renormalization group. The (mass)² of the Higgs doublet evolve towards negative values at low energies giving rise to SU(2) × U(1) breaking as a radiative effect of local supersymmetry breaking. We finally point out the possible relevance of non-renormalizable superpotentials for the problem of fermion masses.     

ΔB = 2 transitions in supersymmetric theories

We carry out a systematic analysis of ΔB = 2 interactions in supersymmetric theories. The selection rules in ΔB = 2 transition depend on the relative value of M (the mass scale that characterizes the ΔB = 2 interactions) and Λ_s (the super-symmetry-breaking scale). In particular, if M ? 10⁴GeV and Λ_s ～ 10²GeV, the effective ΔB = 2 interactions induce NN annihilation in a nucleus yielding two kaons in the final state while processes with only one or zero kaons are suppressed by mixing angles. On the other hand, if M ? 10⁴GeV, then supersymmetry does not imply any additional selection rules beyond those of ordinary (non-supersymmetric) theories.     

Light singlet particles and their cosmological consequences in witten-type supersymmetric models

In a class of supersymmetric gauge models which generate a large mass scale from a supersymmetry breaking mass scale M through loop corrections, there exists generally a very light scalar particle which transforms like a singlet under SU(3)_c × SU(2)_L with no U(1) charge. Cosmological constraints on such a particle are so severe that an upper bound is set on possible values of supersymmetry breaking scale in this class of models as M ? 500 TeV provided that the large mass scale is 10¹⁵ GeV and the mass of the light scalar particle is generated in one-loop order. This bound holds even if the goldstino is not absorbed into the gravitino.     

A grand unified theory based onSU(n, 1)-minimal supergravity

We discuss a grand unified theory in the framework ofSU(n, 1) minimal supergravity with the Planck mass as the only input mass scale.M _W ≈m _3/2 is fixed by radiative corrections to be naturally ?M _P1. Due to the particular form of explicit soft supersymmetry breaking a light singlet can be used to obtain naturally light Higgs doublets and for a new mechanism for radiativeSU (2)×U(1) breaking. The low energy particle spectrum is very restricted withm _3/2≈10⁴ GeV.     

Another calculation of the Higgs mass and the top mass from the principles of H. B. Nielsen: m H ≅ 163GeV for M t ≅ 190GeV

We calculate the Higgs mass and the top mass starting from the principle that there are two, essentially degenerate minima in the Higgs effective potential; the second is at about the Planck energy scale M _P = 1.2 × 10¹⁹ GeV. Thus the parameter of the quartic self-coupling λ _h vanishes, as does β _λH at M _P. The new element is the addition of a quantum interaction term which couples the square of the Higgs field to the square of a pseudoscalar field, in the domain of the energy scale between about 10¹⁴ GeV and M _P. We modify β _λH at one loop. The pseudoscalar field which is introduced may be the field which is responsible for a spontaneous breakdown of discrete symmetry — for CP noninvariance at an energy scale of (10¹⁵–10¹⁶) GeV. The result is then a closer value for m _H ? 163 GeV for the top pole-mass M _t ? 190 GeV; both values are now close to the electroweak scale parameter $\langle {\phi _H}\rangle /\sqrt 2 = 175{\text{ GeV}}$ . In terms of dimensionless running coupling parameters, which determine the masses near to the electroweak scale, we get $\sqrt {{\lambda _H}} \cong 0.06$ and $gt/\sqrt 2 \cong 0.72$ , values that are close to each other and close to unity.     

Constraints on the MSSM from the Higgs sector

We discuss the constraints on supersymmetry in the Higgs sector arising from LHC searches, rare B decays and dark matter direct detection experiments. We show that constraints derived on the mass of the lightest h ⁰ and the CP-odd A ⁰ bosons from these searches are covering a larger fraction of the SUSY parameter space compared to searches for strongly interacting supersymmetric particle partners. We discuss the implications of a mass determination for the lightest Higgs boson in the range 123<M _h <127?GeV, inspired by the intriguing hints reported by the ATLAS and CMS Collaborations, as well as those of a non-observation of the lightest Higgs boson for MSSM scenarios not excluded at the end of 2012 by LHC and direct dark matter searches and their implications on LHC SUSY searches.     

Nambu sum rule in the NJL Models: from superfluidity to top quark condensation

It may appear that the recently found resonance at 125 GeV is not the only Higgs boson. We point out the possibility that the Higgs bosons appear in models of top-quark condensation, where the masses of the bosonic excitations are related to the top quark mass by the sum rule similar to the Nambu sum rule of the NJL models [1]. This rule was originally considered by Nambu for superfluid ³He-B and for the BCS model of superconductivity. It relates the two masses of bosonic excitations existing in each channel of Cooper pairing to the fermion mass. An example of the Nambu partners is provided by the amplitude and the phase modes in the BCS model describing Cooper pairing in the s-wave channel. This sum rule suggests the existence of the Nambu partners for the 125 GeV Higgs boson. Their masses can be predicted by the Nambu sum rule under certain circumstances. For example, if there are only two states in the given channel, the mass of the Nambu partner is ～ 325 GeV. They together satisfy the Nambu sum rule M ₁ ² + M ₂ ² = 4M _t ² , where M _t ～ 174 GeV is the mass of the top quark. If there are two doubly degenerated states, then the second mass is ～210 GeV. In this case the Nambu sum rule is 2M ₁ ² + 2M ₂ ² = 4M _t ² . In addition, the properties of the Higgs modes in superfluid ³He-A, where the symmetry breaking is similar to that of the Standard Model of particle physics, suggest the existence of two electrically charged Higgs particles with masses around 245 GeV, which together also obey the Nambu sum rule M ₊ ² + M _? ² = 4M _t ² .     

Finite temperature behavior of gauge hierarchy models with quantum mechanical resuscitation

We investigate the finite temperature behavior of Dimopoulos and Georgi's hierarchy model where the grand unification scale M_G is naturally generated by the quantum corrections. Owing to the particular form, M²π²(e²lnπ ? 1), of the scalar potential, the first order GUT phase transition takes place at the critical temperature T_c ～ 10^9?12GeV much lower than M_G. If M_G should be of O(M_P) (Planck mass), the universe may undergo an inflationary stage to expand enough. Baryon number asymmetry might be produced by the decay of colored scalars with a mass of 10^10?12 GeV.     

Split supersymmetry in brane models

Type-I string theory in the presence of internal magnetic fields provides a concrete realization of split supersymmetry. To lowest order, gauginos are massless while squarks and sleptons are superheavy. For weak magnetic fields, the correct Standard Model spectrum guarantees gauge coupling unification with sin² ϑW=3/8 at the compactification scale of M _GUT ⋍ 2 × 10¹⁶ GeV. I discuss mechanisms for generating gaugino and higgsino masses at the TeV scale, as well as generalizations to models with split extended supersymmetry in the gauge sector.     

Supersymmetry breaking,open strings and M-theory

We study supersymmetry breaking by Scherk-Schwarz compactifications in type I string theory. While in the gravitational sector all mass splittings are proportional to a (large) compactification radius, supersymmetry remains unbroken for the massless excitations of D-branes orthogonal to the large dimension. In this sector, supersymmetry breaking can then be mediated by gravitational interactions alone, that are expected to be suppressed by powers of the Planck mass. The mechanism is non-perturbative from the heterotic viewpoint and requires a compactification radius at intermediate energies of order 10¹²−10¹⁴ GeV This can also explain the value of Newton's constant if the string scale is close to the unification scale, of order 10¹⁶ GeV.     

Radiative decays of quarkonia into Goldstone fermions

We consider the decay of³ S ₁ quarkonia into a photon and two Goldstone fermions in a model realizing supersymmetry in a nonlinear way. We derive a lower bound of 3.5 GeV for the scale of spontaneous supersymmetry breaking from Υ-decays. We show that the decay of a³ S ₁ quarkonium into two Goldstone fermions is forbidden in the order we consider.     

Limits to possible scalar-boson mass and coupling from e+e− collisions

Measurements of e⁺e^? → e⁺e^? at 2.8 GeV are reported and interpreted in terms of limits for the mass and coupling of a possible scalar boson of the type introduced in recent renormalizable models of weak interactions. In particular, in the Georgi-Glashow scheme of leptons we find that the scalar boson mass must be larger than 10 GeV for an m_W = 10 GeV (m_W mass of the W-boson) and of 6.5 GeV for m_W = 15 GeV. Alternatively its coupling is extremely weak.     

A low right-handed scale in a supersymmetric context

We investigate the prospects for a low right-handed scale M_R in the context of locally supersymmetric O(10), limiting ourselves to the most interesting case of a single breaking scale between the grand unified scale M_X and the W-mass. It is found that supersymmetry seems to imply a unique solution as regards the Higgs content and the intermediate symmetry group if a low right-handed scale (less than 10⁴ GeV) exist at all. Apart from a minimal set of representations providing the symmetry battern, the Higgs sector consist of a pair of 16 and $\text{16}$ spinor representations ying at scale M_R and the residual symmetry is SU(3)_c × U(1)_B?L × SU(2)_L × U(1)_R.     

Diffraction dissociation in the reaction p+p→Λ°+K++p at the CERN ISR

The exclusive reaction pp→Λ°K⁺p has been studied at 0.1<?t_pp<0.6 GeV² and energies √s=45 GeV and 53 GeV at the CERN ISR. Diffractive excitation p→Λ°K⁺ occurs predominantly in the mass range M(Λ°K⁺)≈2.1 GeV and peaks at 1.7 GeV. The cross section for pp→Λ°K⁺p is 10±3μb for M(Λ°K⁺)<2.5 GeV, and the t_pp dependence is exp (bt) with b=7.0±0.5 GeV^?2.     

Resonances in the ωω system

Results of a partial-wave analysis for the reaction π ^? → ωωn studied at the VES spectrometer (Institute for High Emergy Physics, Protvino) are presented. The behavior of the J ^PC = 2⁺⁺ amplitudes in the ωω system is described by the f ₂(1565) and f ₂(1910) resonances, whose parameters were fixed at M = 1.590 ± 0.010 GeV and Γ = 0.140 ± 0.011 GeV for the former and at M = 1.890 ± 0.010 GeV and Γ = 0.165 ± 0.019 GeV for the latter. The decay f ₄(2050) → ωω was observed at parameters values of M = 1.960 ± 0.015 GeV, Γ = 0.290 ± 0.020 GeV.     

Cosmological and astrophysical bounds on the scale of supersymmetry breaking

We derive an upper bound f < 10⁶ GeV on the scale of the breaking of supersymmetry from the mass density of the universe and a lower bound f 40 GeV from stellar evolution.     

Ultra heavy fermion bound states via Higgs exchange

We study the characteristic features of the ultra heavy fermion bound state via Higgs exchange. The constraint under which such a bound state occurs is presented. For a typical example of Higgs and fermion mass, M_H≅ 100 GeV / c² and M_F≅ 700 GeV/c², the wave function at the origin of the bound states via Higgs exchange becomes about 100 times larger than that via gluon exchange.     

Search for heavy quasistable leptons

Negative results of a search for heavy quasistable charged leptons at the IHEP accelerator are reported. For the selection of heavy leptons a system of scintillation and gas ?erenkov counters was used. The upper limit estimations of the differential cross sections for heavy lepton production in pN collisions at E_p = 70 GeV are, for example, d²σ/dpω (p = 30 GeV/c, θ = 2 mrad, 1 ? M_λ ? 4.8 GeV) = 4.10^?38 cm²/sr · GeV. The results of the present work, together with the data on muon pair production in nucleon-nucleon interactions, show that there are no heavy charged leptons with masses from 0.55 GeV (τ_λ > 7 · 10^?10 sec) up to 4.5 GeV (τ_λ > 3 · 10^?8 sec).     

The mass difference of the KL and KS mesons in the chiral quark-loop model

The low-energy (the long-distance) contribution is calculated to the K_L − K_S mass difference: δM_(LD) = 1.4 × 10⁻¹⁵ GeV. The estimation of δM_(SD) (the short-distance contribution) is made. Strong low-energy interactions are described in the chiral quark-loop model. Weak interaction is described with the use of the effective lagrangian obtained in the standard Kobayashi-Maskawa model with the account of QCD-interaction.     

Search for narrow resonances in the reaction γ + Be → e+e− + X at 1.8 ⩽ Me+e− ⩽ 2.6 GeV

The reaction γ + Be → e⁺e^? + X was studied with a bremsstrahlung beam of 7.2 GeV maximum energy. For invariant pair masses 1.8 ? M_e⁺e^? 2.6 GeV, no evidence for narrow resonance of width smaller than 40 MeV was found. For the mass interval 2.1 ? M_e⁺e^? ? 2.6 GeV, we obtained an upper limit of σ · B_e⁺e^? < 2 × 10^?35 cm²/nucleon (90% confidence level), assuming a production mechanism similar to the θ (1019) meson.