Mario Abud

Batalin-Vilkovisky approach to the metric independence of TQFT

Abstract We address the problem of metric independence of the partition function of TQFT in the BV formalism. This generalizes results which are valid only where the Faddeev-Popov type gauge-fixing works. Our treatment includes, without difficulties, the interesting cases of theories with open BRST algebras (such as BF theories). We explicitly consider a few theories based on p -forms to show that they lead to metric independent partition functions.

A BRST lagrangian quantization of reducible gauge theories: Non-abelian p -forms and string field theories

SummaryBy a suitable deformation of the reducible BRST algebra of the Abelianp-forms we obtain an explicit nilpotent BRST for the corresponding open reducible non-Abelianp-forms theory. We consider the Freedman-Townsend model and the corresponding (topological) massless limit. This allows us to perform a standard BRST quantization of the theory which avoids the Batalin-Vilkovisky formalism. This procedure leads to the introduction of auxiliary fields (related to BV antifields) which assume a universal form in terms of a single object belonging to the universal enveloping algebra. The auxiliary fields are interpreted as a sort of connection. A formal extension to the case of string field theory is presented.

Consistent anomalies of the induced W gravities

Abstract The BRST anomaly which may be present in the induced W n gravity quantized on the light-cone is evaluated in the geometrical framework of Zucchini. The cocycles linked by the cohomology of the BRST operator to the anomaly are straightforwardly calculated thanks to the analogy between this formulation and the Yang-Mills theory. We give also a conformally covariant formulation of these quantities including the anomaly, which is valid on arbitrary Riemann surfaces. The example of the W 3 theory is discussed and a comparison with other candidates for the anomaly available in the literature is presented.

Stability of spontaneous symmetry breaking in SO(10)

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.

SO(10) inspired seesaw mechanism

We determine the νR 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 (MR)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 MR in the range 1011–1012 GeV in agreement with Pati–Salam intermediate symmetry. We find also solutions with smaller neutrino masses, for which the scale of MR depends on the solution to the solar neutrino problem and on the value of the component of νe along the highest mass eigenstate, Ue3.

LIGHT MASSES IN SHORT DISTANCE PENGUIN LOOPS

Abstract Penguin diagrams for decays such as b →( s , d ) γ involve virtual loops of u or other light quarks. Logarithms of the virtual quark mass could, in principle, influence the phenomenological analysis of the decay. It is thus important to study these logarithms to all orders in QCD perturbation theory. In this paper we show that, at arbitrary order, the matrix elements of operators in the effective hamiltonian contributing to b → sγ are finite for the limit of m u →0 in penguin loops.

Algebraic determination of covariant anomalies and Schwinger terms

Abstract Inclusion of the anti-ghost field in the BRST algebra allows us to derive simultaneously consistent and covariant anomalies and Schwinger terms (as well as Bardeen-Zumino counter-terms) by transgression from a Chern-Simons form. Our method which uses the natural variables of the gauged BRST symmetry encompasses all polynomials and descent equations of a previously proposed approach which relies on various homotopy operators. In conclusion, both approaches are generalized to gravitational theories.

Hints for the existence of hexaquark states in the baryon-antibaryon sector

The discovery of some baryon-antibaryon resonances has led us to consider 3q 3q systems as possible candidates. We predict their spectrum in the framework of a constituent model, where the chromomagnetic interaction plays the main role. The relevant parameters are fixed by the present knowledge of 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 a{sub 0}(Y) in the hidden strangeness sector and the Y(4140) and X(4350) in the cscs sector. A detailed account of the spectra and the decay channels is provided for future comparisons with data.

NEUTRINO MASSES AND MIXINGS INSO(10)M

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.

NEUTRINO MASSES AND MIXINGS IN SO(10)M

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.