118087093
Properties of possible composite lepton states induced by neutrinos
SummaryIn the hypothesis that the long-range forces due to exchange of neutrino pairs between leptons remain unaltered up to distances of the order of the square root of the Fermi coupling constant, the possibility of existence of lepton-antilepton massless vector bound states is considered and studied with a Bethe-Salpeter equation in the ladder approximation. The equation is reduced to a system of coupled Fredholm integral equations for the spectral function of the vertex free-lepton-bound-state. In the zeroth-order approximation the form factor of the vertex is given and the effective renormalized coupling constant computed. It turns out to be rather insensitive to the dependence of the neutrino forces from the distance near the origin (with exception of the Coulomb dependence) and in our approximation it results about 7 times larger than the electric one. This result is interpreted as an indication that also for leptons the electromagnetic vertex must be conceived as belonging to a higher-symmetry invariant vertex.RiassuntoNell’ipotesi che le forze a lungo raggio dovute allo scambio di coppie di neutrini tra leptoni agiscano fino a distanze dell’ordine della radice della costante di Fermi, si considera la possibile esistenza di stati legati leptone-antileptone, vettoriali di massa zero, a mezzo di una equazione di Bethe-Salpeter. L’equazione si riduce ad un sistema di equazioni di Fredholm per la funzione spettrale del vertice leptoni liberi-stato legato. Nell’approssimazione di ordine zero si dà il fattore di forma del vertice e si calcola la costante d’accoppiamento rinormalizzata. Questa risulta poco dipendente dalla forma della regolarizzazione e dall’andamento delle forze neutriniche a distanze molto piccole. Nelle nostre approssimazioni la costante d’accoppiamento risulta all’incirca sette volte più grande della carica elettrica. Questo risultato è interpretato come un’indicazione che anche per i leptoni il vertice elettromagnetico è una componente di un vertice invariante rispetto a un gruppo di simmetria più elevato che nonU1.РеэюмеРассматривается воэможность сушествования лептон-антилептонных векторных свяэанных состояний с нулевой массой, предполагая, что длиннодейст-вуюшие силы, обусловленные обменом нейтринных пар, между лептонами сохра-няются неиэменными вплоть до расстояний порядка квадратного корня иэ фер-миевской константы свяэи. Исследование проводится с помошью уравнения Бете-Салпетера в лестничном приближении. Это уравнение сводится к системе свяэанных интегральных уравнений Фредгольма для спектральной функции верщины «сво-бодный лептон — свяэанное состояние». Приводится выражение форм-фактора верщины в нулевом приближении и вычисляется зффективная перенормированная константа свяэи. Окаэывается, что зтот реэультат довольно нечувствителен к эави-симости нейтринных сил от расстояния вблиэи источника (эа исключением куло-новской эависимости) и в нащем приближении константа свяэи в семь раэ больще, чем злектрическая. Этот реэультат интерпретируется как укаэание, что также для лептонов злектромагнитная верщина должна рассматриваться, как принадлежашая инвариантной верщине более высокой симметрии.
118403927
Singular vector of W algebras via DS reduction of A2(1)
The BRST quantisation of the Drinfeld-Sokolov reduction applied to the case of A2(1) is explored to construct in an unified and systematic way the general singular vectors in W3 and W3(2) Verma modules. The construction relies on the use of proper quantum analoques of the classic DS gauge fixing transformations. Furthermore the stability groups W(gh) of the highest weights of the W Verma modules play an important role in the proof of the BRST equivalence of the Malikov-Feigin-Fuks singular vectors and the W algebra ones. The resulting singulary vectors are essentially classified by the affine Weyl group W modulo Wη. This is a detailed presentation of the results announced in a recent of theauthors.
12289422
Non-critical string pentagon equations and their solutions
We derive pentagon-type relations for the three-point boundary tachyon correlation functions in the non-critical open string theory with generic cmatter < 1 and study their solutions in the case of Fateev–Zamolodchikov–Zamolodchikov branes. A new general formula for the Liouville boundary three-point factor corresponding to degenerate matter is derived.
120683606
Exchange relations and correlation functions for a quantum particle on the SU2 group manifold
The SO4 invariant quantum dynamics of a point particle moving on the 3 sphere (or equivalently, of the relative motion of the spherical top) is considered. Quantum exchange relations for different times are derived with an ‘‘R matrix’’ depending on the time difference and on the conserved angular momentum. Their implications for correlation functions are spelled out. The chiral exchange relations of Alekseev and Faddeev [Commun. Math. Phys. 141, 413–422 (1991)] are also extended to different times.
16434321
Operator realization of the SU(2) WZNW model
Decoupling the chiral dynamics in the canonical approach to the WZNW model requires an extended phase space that includes left and right monodromy variables M and M. Earlier work on the subject, which traced back the quantum group symmetry of the model to the Lie-Poisson symmetry of the chiral symplectic form, left some open questions: 
• 
- How to reconcile the necessity to set MM−1 = 1 (in order to recover the monodromy invariance of the local 2D group valued field g = uu) with the fact the M and M obey different exchange relations? 
 
• 
- What is the status of the quantum symmetry in the 2D theory in which the chiral fields u(x−t) and u(x + t) commute? 
 
• 
- Is there a consistent operator formalism in the chiral (and the extended 2D) theory in the continuum limit? 
 
 
 
 
We propose a constructive affirmative answer to these questions for G = SU(2) by presenting the quantum fields u and u as sums of products of chiral vertex operators and q-Bose creation and annihilation operators.
125161041
Weyl Fields as a Basis for Unitary Symmetry
199514134
SURVEY AND ALIGNMENT FOR THE SYNCHROTRON LIGHT SOURCE ELETTRA
ELETTRA is a third generation light Source currently under construction in Trieste, Italy, which will be commissioned in 1993. As a high brilliance machine, ELETTRA is designed for extremely small emittance, which causes a high sensitivity to alignment errors. First results and the general alignment method, as well as the instruments, survey tools and applied software, are described.