[Show abstract][Hide abstract] ABSTRACT: We consider the constraints on SO(10) unified models coming from the lower
limits on proton lifetime and on the scale of B-L symmetry breaking within the
framework of the seesaw model for neutrino masses. By upgrading a triangular
relationship for the inverse of Majorana masses to the experimental situation
with non maximal 2-3 mixing and non vanishing 1-3 mixing, we get for the sum of
neutrino masses the upper limit 0.16 eV.
[Show abstract][Hide abstract] ABSTRACT: Assuming a Zee-like matrix for the right-handed neutrino Majorana masses in the seesaw mechanism, one gets maximal mixing for vacuum solar oscillations, a very small value for Ue3 and an approximate degeneracy for the two lower neutrino masses. The scale of right-handed neutrino Majorana masses is in good agreement with the value expected in an SO(10)M model with Pati–Salam SU(4)×SU(2)×SU(2) intermediate symmetry.
Modern Physics Letters A 11/2011; 15(01). DOI:10.1142/S0217732300000049 · 1.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the framework of SO(10) gauge unification and the seesaw mechanism, we
show that the upper bound on the mass of the heaviest right-handed neutrino
$M_{R_3} < 3 \times 10^{11}$ GeV, given by the Pati-Salam intermediate scale of
$B-L$ spontaneous symmetry breaking, constrains the observables related to the
left-handed light neutrino mass matrix. We assume such an upper limit on the
masses of right-handed neutrinos and, as a first approximation, a Cabibbo form
for the matrix $V^L$ that diagonalizes the Dirac neutrino matrix $m_D$. Using
the inverse seesaw formula, we show that our hypotheses imply a triangular
relation in the complex plane of the light neutrino masses with the Majorana
phases. We obtain normal hierarchy with an absolute scale for the light
neutrino spectrum. Two regions are allowed for the lightest neutrino mass $m_1$
and for the Majorana phases, implying predictions for the neutrino mass
measured in Tritium decay and for the double beta decay effective mass
$|<m_{ee}>|$.
[Show abstract][Hide abstract] ABSTRACT: The discovery of some baryon-antibaryon resonances has led us to consider 3q~3\bar{q} systems as possible candidates. We predict their spectrum in the framework of a constituent model, where the chromo-magnetic interaction plays the main role. The relevant parameters are fixed by the present knowledge on tetraquarks. The emerging scenario complies well with experiment. Besides the description of the baryon-antibaryon resonances, we find evidence for new tetraquark states, namely the a0(Y) in the hidden strangeness sector and, in the cs\bar{c}\bar{s} sector, the Y(4140) and the X(4350). A detailed account of the spectra and the decay channels is provided for future comparisons with data. Comment: 17 pages
[Show abstract][Hide abstract] ABSTRACT: We present the spectrum of the lightest pentaquark states of both parities and compare it with the present experimental evidence for these states. We have assumed that the main role for their mass splittings is played by the chromo-magnetic interaction. We have also kept into account the $SU(3)_F$ breaking for their contribution and for the spin orbit term. The resulting pattern is in good agreement with experiment.
Advanced Studies in Theoretical Physics 07/2008; 2(19).
[Show abstract][Hide abstract] ABSTRACT: We determine the nu_{R} Majorana mass matrix from the experimental data on
neutrino oscillations in the framework of a see-saw SO(10) model, where we
impose the condition (M^R)_{33} = 0 to avoid too large fine-tunings in the
see-saw formula. We find a class of solutions with the two lowest neutrino
masses almost degenerate and the scale of the matrix elements of M^R in the
range 10^{11} -10^{12} GeV in agreement with Pati-Salam intermediate symmetry.
We find also solutions with smaller neutrino masses, for which the scale of M_R
depends on the solution to the "solar neutrino problem" and on the value of the
component of \nu_e along the highest mass eigenstate, U_{e3}.
International Journal of Modern Physics A 02/2001; 16(04):609-623. DOI:10.1142/S0217751X01003056 · 1.70 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Assuming a Zee-like matrix for the right-handed neutrino Majorana masses in the see-saw mechanism, one gets maximal mixing for vacuum solar oscillations, a very small value for $U_{e3}$ and an approximate degeneracy for the two lower neutrino masses. The scale of right-handed neutrino Majorana masses is in good agreement with the value expected in a SO(10) model with Pati-Salam $SU(4)\ts SU(2)\ts SU(2)$ intermediate symmetry. Comment: 11 pages, no figures. References added
Modern Physics Letters A 11/1999; 15(1). DOI:10.1016/S0217-7323(00)00004-9 · 1.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A unified gauge model is built with Higgs in 210SU(3)c ÄSU(2)L ÄSU(2)R ÄU(1)B - L .SU(3)_c \otimes SU(2)_L \otimes SU(2)_R \otimes U(1)_{B - L} .
. The vacuum of the210 is in a two-dimensional stratum. From the values sin2
\fracaas (MW )\frac{\alpha }{{\alpha _s }}(M_W )
one determines the high scales, with the result to predict leptoquarks heavier than 1015 GeV and Majorana masses for the right-handed neutrinos around 1011 GeV.
Zeitschrift für Physik C 01/1989; 44(4):589-598. DOI:10.1007/BF01549081
[Show abstract][Hide abstract] ABSTRACT: We have examined the description of the nucleon as soliton of an effective chiral lagrangian, in which the ρ meson is identified with the gauge boson of an hidden symmetry. We calculate some physical quantities of the nucleon. Numerical calculations seem to indicate that, though this model provides the soliton stabilization, it does not improve other static parameters.
Physics Letters B 03/1987; 187(3-4):390-394. DOI:10.1016/0370-2693(87)91116-6 · 6.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The stability of the breaking of SO(10) into SO(6) × SO(4) with Higgs in the 54 representation is studied in the range of scales 1016-1019 GeV. One finds constraints on the parameters of the potential.
Nuclear Physics B 01/1986; 263(2):336-346. DOI:10.1016/0550-3213(86)90121-5 · 3.93 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We have reexamined the description of the low-energy QCD physics in terms of the chiral symmetry group G = SU(2) ⊗ SU(2)⊗UV(1) broken spontaneously down to H = SU(2)⊗UV(1). The resultant effective lagrangian admits an extra hidde local symmetry group isomorphic to H, which can be gauged, as suggested by Bando et al., yielding the physics of the vector mesons. Moreover, the “strong coupling” approximation in terms of the gauge coupling constant leads precisely to the Skyrme form of non-linear sigma model. The possibility of improved phenomenology in the baryon sector over usual skyrmion physics is discussed.
Physics Letters B 09/1985; 159(2-3-159):155-160. DOI:10.1016/0370-2693(85)90877-9 · 6.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Results are presented of the minimization of the Higgs potential for the irreducible representation 75 of SU(5). Isotropy groups of minima are determined using a geometrical method developed recently by Abud and Sartori. Minima with the maximal isotropy algebras su(3)+su(2)+u(1), sp(4)+u(1), su(2)+su(2)+u(1) and su(2) were found as well as a minimum with a non-maximal isotropy algebra su(2)+su(2)+u(1)+u(1) and discrete symmetry. A minimum having a non-maximal isotropy group SU(2)xU(1)xU(1) was also found, contrary to Michel's conjecture. A detailed analysis of the results is presented and the limits of Michel's conjecture are pointed out.
Annals of Physics 06/1985; 162(1):155-191. DOI:10.1016/0003-4916(85)90232-5 · 2.10 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We have found a minimum of the Higgs potential for the representation 75 of SU(5) having a non maximal little group with algebra su(2) + u(1), contrary of Michel's conjecture. We also find a minimum with non maximal little algebra su(2) + su(2) + u(1) and discrete symmetry, and minima with maximal little algebra su(3) + su(2) + u(1), sp94) + u(1), su(2) + su(2) + u(1) and su(2).
Physics Letters B 08/1984; 142(5-6-142):371-374. DOI:10.1016/0370-2693(84)91342-X · 6.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We study the little groups of the minima of the Higgs potential built on the representation 75 of SU(5). We find a minimum with a non maximal little subalgebra, but an additional discrete group so that the little group is maximal. We find a large class of minimas with su(3) + su(2) + u(1) little algebra.
Lecture Notes in Physics 01/1984; DOI:10.1007/BFb0016136
[Show abstract][Hide abstract] ABSTRACT: The problem of classifying the theoretically allowed patterns of spontaneous symmetry breading, in theories where the ground state is determined as a minimum of a G-invariant potential (G a compact group of transformations), is analyzed. A detailed, complete, and rigorous justification of a recently proposed approach to the determination of the minima of G-invariant potentials (M. Abud and G. Sartori, Phys. Lett. B104 (1981), 147) is presented. The results are obtained through an analysis of the geometry of the finite-dimensional representations of G, which leads to a complete characterization of the structure of orbit space and its partition in subsets (strata) formed by orbits with the same symmetry under G-transformations (orbit type), and to a new theorem stating that the gradients of complex analytic G-invariant functions annihilate on one-dimensional strata. Polynomial potentials in particular are studied. Conditions for instability of the residual symmetry (second-order phase transitions) are determined.
Annals of Physics 10/1983; 150(2-150):307-372. DOI:10.1016/0003-4916(83)90017-9 · 2.10 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Calculation of Wilson loops (WL) to second order, are performed for different shapes of the path, using dimensional regularization techniques. Some useful formulae are developed. In particular, a discussion is given on the influence of points of contact, cusps and intersections, on the residue of the resultant pole. For smooth curves WLs are finite.
Nuclear Physics B 09/1982; 204(1):109-117. DOI:10.1016/0550-3213(82)90424-2 · 3.93 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Starting from an analysis of the geometry of orbit-space, we propose a new approach to the determination of those extrema of a G-invariant C∞-function (G is a compact linear group), which are associated to an arbitrary, but fixed, residual symmetry group. When applied to Higgs potentials of unified gauge field theories, the method allows one to state conditions for the minima to exist and be natural (stable) and to clarify the origin of a class of pseudo-Goldstone bosons.
Physics Letters B 08/1981; 104(2-104):147-152. DOI:10.1016/0370-2693(81)90578-5 · 6.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: High-energy two-photon collisions will be responsible for a large fraction of events in e+e- machines such as PETRA, PEP, and LEP. We suggest measuring the energy pattern of the γγ processes, which would provide very interesting information on the interplay between electromagnetic and strong interactions. The angular distribution of the hadronic energy (antenna pattern) is calculated for photon-photon collisions. By using energy-conservation sum rules, we give a model-independent, reliable computation of the corrections due to color confinement, as well as heavy-quark masses and decays. The contributions from the quantum chromodynamics (QCD) structure of the photon, which are characterized by three or four jets in the final state, are taken into account. The energy correlation, i.e.; the hadronic energy radiated through two calorimeters as a function of the relative angle is also calculated. We evaluate the energy pattern and energy correlation for the formation of C-even bound states, and find that an extremely good resolution in the hadronic energy would be needed in order to disentangle the bound-state contribution from the background. We present a detailed discussion of the two-photon processes as a background in the studies of the energy pattern of the e+e- annihilation into hadrons. By requiring that either the total hadronic energy or the invariant hadronic mass is larger than 60% of their maximum value, √s, the γγ background should be suppressed enough to allow for the experimental tests of QCD in e+e- annihilation which have been recently proposed.
Physical Review D 10/1979; 20(9). DOI:10.1103/PhysRevD.20.2224 · 4.64 Impact Factor