274 research outputs found
Construction of matryoshka nested indecomposable N-replications of Kac-modules of quasi-reductive Lie superalgebras, including the sl(m/n) and osp(2/2n) series
We construct a new class of finite dimensional indecomposable representations
of simple superalgebras which may explain, in a natural way, the existence of
the heavier elementary particles. In type I Lie superalgebras sl(m/n) and
osp(2/2n), one of the Dynkin weights labeling the finite dimensional
irreducible representations is continuous. Taking the derivative, we show how
to construct indecomposable representations recursively embedding N copies of
the original irreducible representation, coupled by generalized Cabibbo angles,
as observed among the three generations of leptons and quarks of the standard
model. The construction is then generalized in the appendix to quasi-reductive
Lie superalgebras.Comment: Revised version 2 with minor modifications. On the suggestion of the
referee, we show that the construction does not apply to the psl(n/n)
superalgebras. 15 pages, 32 references Revised version 3 no modification
except reformatting the bibliography and adding do
Masur-Veech volumes and intersection theory: the principal strata of quadratic differentials
We describe a conjectural formula via intersection numbers for the
Masur-Veech volumes of strata of quadratic differentials with prescribed zero
orders, and we prove the formula for the case when the zero orders are odd. For
the principal strata of quadratic differentials with simple zeros, the formula
reduces to compute the top Segre class of the quadratic Hodge bundle, which can
be further simplified to certain linear Hodge integrals. An appendix proves
that the intersection of this class with -classes can be computed by
Eynard-Orantin topological recursion.
As applications, we analyze numerical properties of Masur-Veech volumes, area
Siegel-Veech constants and sums of Lyapunov exponents of the principal strata
for fixed genus and varying number of zeros, which settles the corresponding
conjectures due to Grivaux-Hubert, Fougeron, and elaborated in [the7]. We also
describe conjectural formulas for area Siegel-Veech constants and sums of
Lyapunov exponents for arbitrary affine invariant submanifolds, and verify them
for the principal strata
On the Decomposition of Clifford Algebras of Arbitrary Bilinear Form
Clifford algebras are naturally associated with quadratic forms. These
algebras are Z_2-graded by construction. However, only a Z_n-gradation induced
by a choice of a basis, or even better, by a Chevalley vector space isomorphism
Cl(V) \bigwedge V and an ordering, guarantees a multi-vector decomposition
into scalars, vectors, tensors, and so on, mandatory in physics. We show that
the Chevalley isomorphism theorem cannot be generalized to algebras if the
Z_n-grading or other structures are added, e.g., a linear form. We work with
pairs consisting of a Clifford algebra and a linear form or a Z_n-grading which
we now call 'Clifford algebras of multi-vectors' or 'quantum Clifford
algebras'. It turns out, that in this sense, all multi-vector Clifford algebras
of the same quadratic but different bilinear forms are non-isomorphic. The
usefulness of such algebras in quantum field theory and superconductivity was
shown elsewhere. Allowing for arbitrary bilinear forms however spoils their
diagonalizability which has a considerable effect on the tensor decomposition
of the Clifford algebras governed by the periodicity theorems, including the
Atiyah-Bott-Shapiro mod 8 periodicity. We consider real algebras Cl_{p,q} which
can be decomposed in the symmetric case into a tensor product Cl_{p-1,q-1}
\otimes Cl_{1,1}. The general case used in quantum field theory lacks this
feature. Theories with non-symmetric bilinear forms are however needed in the
analysis of multi-particle states in interacting theories. A connection to
q-deformed structures through nontrivial vacuum states in quantum theories is
outlined.Comment: 25 pages, 1 figure, LaTeX, {Paper presented at the 5th International
Conference on Clifford Algebras and their Applications in Mathematical
Physics, Ixtapa, Mexico, June 27 - July 4, 199
A limiting velocity for quarkonium propagation in a strongly coupled plasma via AdS/CFT
We study the dispersion relations of mesons in a particular hot strongly
coupled supersymmetric gauge theory plasma. We find that at large momentum k
the dispersion relations become omega = v_0 k + a + b/k + ..., where the
limiting velocity v_0 is the same for mesons with any quantum numbers and
depends only on the ratio of the temperature to the quark mass T/m_q. We
compute a and b in terms of the meson quantum numbers and T/m_q. The limiting
meson velocity v_0 becomes much smaller than the speed of light at temperatures
below but close to T_diss, the temperature above which no meson bound states at
rest in the plasma are found. From our result for v_0, we find that the
temperature above which no meson bound states with velocity v exist is
T_diss(v) \simeq (1-v^2)^(1/4) T_diss, up to few percent corrections.We thus
confirm by direct calculation of meson dispersion relations a result inferred
indirectly in previous work via analysis of the screening length between a
static quark and antiquark in a moving plasma. Although we do not do our
calculations in QCD, we argue that the qualitative features of the dispersion
relation we compute, including in particular the relation between dissociation
temperature and meson velocity, may apply to bottomonium and charmonium mesons
propagating in the strongly coupled plasma of QCD. We discuss how our results
can contribute to understanding quarkonium physics in heavy ion collisions.Comment: 57 pages, 12 figures; references adde
Double Counting Ambiguities in the Linear Sigma Model
We study the dynamical consequences imposed on effective chiral field
theories such as the quark-level SU(2) linear model (LM) due
to the fundamental constraints of massless Goldstone pions, the normalization
of the pion decay constant and form factor, and the pion charge radius. We
discuss quark-level double counting LM ambiguities in the context of
the Salam-Weinberg compositeness condition. Then SU(3) extensions to
the kaon are briefly considered.Comment: 23 pages To be published in Journal of Physics
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