4,754 research outputs found
Color-octet scalar effects on Higgs boson production in gluon fusion
We compute the next-to-next-to-leading order QCD corrections to the
gluon-fusion production of a Higgs boson in models with massive color-octet
scalars in the representation using an effective-theory
approach. We derive a compact analytic expression for the relevant Wilson
coefficient, and explain an interesting technical aspect of the calculation
that requires inclusion of the quartic-scalar interactions at
next-to-next-to-leading order. We perform a renormalization-group analysis of
the scalar couplings to derive the allowed regions of parameter space, and
present phenomenological results for both the Tevatron and the LHC. The
modifications of the Higgs production cross section are large at both
colliders, and can increase the Standard Model rate by more than a factor of
two in allowed regions of parameter space. We estimate that stringent
constraints on the color-octet scalar parameters can be obtained using the
Tevatron exclusion limit on Higgs production.Comment: 18 pages, 6 figures, 3 table
Limits of elliptic hypergeometric biorthogonal functions
The purpose of this article is to bring structure to (basic) hypergeometric
biorthogonal systems, in particular to the q-Askey scheme of basic
hypergeometric orthogonal polynomials. We aim to achieve this by looking at the
limits as p->0 of the elliptic hypergeometric biorthogonal functions from
Spiridonov, with parameters which depend in varying ways on p. As a result we
get 38 systems of biorthogonal functions with for each system at least one
explicit measure for the bilinear form. Amongst these we indeed recover the
q-Askey scheme. Each system consists of (basic hypergeometric) rational
functions or polynomials.Comment: 27 pages. This is a self-contained article which can also be seen as
part 1 of a 3 part series on limits of (multivariate) elliptic hypergeometric
biorthogonal functions and their measure
Superconformal indices of three-dimensional theories related by mirror symmetry
Recently, Kim and Imamura and Yokoyama derived an exact formula for
superconformal indices in three-dimensional field theories. Using their
results, we prove analytically the equality of superconformal indices in some
U(1)-gauge group theories related by the mirror symmetry. The proofs are based
on the well known identities of the theory of -special functions. We also
suggest the general index formula taking into account the global
symmetry present for abelian theories.Comment: 17 pages; minor change
Local realizations of -Oscillators in Quantum Mechanics
Representations of the quantum q-oscillator algebra are studied with
particular attention to local Hamiltonian representations of the Schroedinger
type. In contrast to the standard harmonic oscillators such systems exhibit a
continuous spectrum. The general scheme of realization of the q-oscillator
algebra on the space of wave functions for a one-dimensional Schroedinger
Hamiltonian shows the existence of non-Fock irreducible representations
associated to the continuous part of the spectrum and directly related to the
deformation. An algorithm for the mapping of energy levels is described.Comment: 12 pages, LaTeX, Phys. Lett. A, to be publishe
Higgs Boson Production from Black Holes at the LHC
If the fundamental Planck scale is near a TeV, then TeV scale black holes
should be produced in proton-proton collisions at the LHC where \sqrt{s} = 14
TeV. As the temperature of the black holes can be ~ 1 TeV we also expect
production of Higgs bosons from them via Hawking radiation. This is a different
production mode for the Higgs boson, which would normally be produced via
direct pQCD parton fusion processes. In this paper we compare total cross
sections and transverse momentum distributions d\sigma/dp_T for Higgs
production from black holes at the LHC with those from direct parton fusion
processes at next-to-next-to-leading order and next-to-leading order
respectively. We find that the Higgs production from black holes can be larger
or smaller than the direct pQCD production depending upon the Planck mass and
black hole mass. We also find that d\sigma/dp_T of Higgs production from black
holes increases as a function of p_T which is in sharp contrast with the pQCD
predictions where d\sigma/dp_T decreases so we suggest that the measurement of
an increase in d\sigma/dp_T as p_T increases for Higgs (or any other heavy
particle) production can be a useful signature for black holes at the LHC.Comment: 20 pages latex, 5 figures, To appear in Phys. Rev.
S-duality and 2d Topological QFT
We study the superconformal index for the class of N=2 4d superconformal
field theories recently introduced by Gaiotto. These theories are defined by
compactifying the (2,0) 6d theory on a Riemann surface with punctures. We
interpret the index of the 4d theory associated to an n-punctured Riemann
surface as the n-point correlation function of a 2d topological QFT living on
the surface. Invariance of the index under generalized S-duality
transformations (the mapping class group of the Riemann surface) translates
into associativity of the operator algebra of the 2d TQFT. In the A_1 case, for
which the 4d SCFTs have a Lagrangian realization, the structure constants and
metric of the 2d TQFT can be calculated explicitly in terms of elliptic gamma
functions. Associativity then holds thanks to a remarkable symmetry of an
elliptic hypergeometric beta integral, proved very recently by van de Bult.Comment: 25 pages, 11 figure
On a modular property of N=2 superconformal theories in four dimensions
In this note we discuss several properties of the Schur index of N=2
superconformal theories in four dimensions. In particular, we study modular
properties of this index under SL(2,Z) transformations of its parameters.Comment: 23 page, 2 figure
Relation between the 4d superconformal index and the S^3 partition function
A relation between the 4d superconformal index and the S^3 partition function
is studied with focus on the 4d and 3d actions used in localization. In the
case of vanishing Chern-Simons levels and round S^3 we explicitly show that the
3d action is obtained from the 4d action by dimensional reduction up to terms
which do not affect the exact results. By combining this fact and a recent
proposal concerning a squashing of S^3 and SU(2) Wilson line, we obtain a
formula which gives the partition function depending on the Weyl weight of
chiral multiplets, real mass parameters, FI parameters, and a squashing
parameter as a limit of the index of a parent 4d theory.Comment: 20 pages, LaTeX; v2: comments added; v3: minor corrections, version
published in JHE
Unit circle elliptic beta integrals
We present some elliptic beta integrals with a base parameter on the unit
circle, together with their basic degenerations.Comment: 15 pages; minor corrections, references updated, to appear in
Ramanujan
A "missing" family of classical orthogonal polynomials
We study a family of "classical" orthogonal polynomials which satisfy (apart
from a 3-term recurrence relation) an eigenvalue problem with a differential
operator of Dunkl-type. These polynomials can be obtained from the little
-Jacobi polynomials in the limit . We also show that these polynomials
provide a nontrivial realization of the Askey-Wilson algebra for .Comment: 20 page
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