121477714
Publisher's Note: Unparticle physics in diphoton production at the CERN LHC [Phys. Rev. D 77, 055013 (2008)]
121827797
Finite tension strings in SU(2) gauge theory
Abstract The second-order field equations of the SU(2) Higgs model are studied and a new class of string solutions is obtained. The tension is finite and scale-dependent and the strings are of minus one unit flux.
119270253
NNLO QCD corrections to the resonant sneutrino/slepton production at hadron colliders
We present a complete next to next to leading order QCD corrections to the resonant sneutrino and charged slepton production cross sections at hadronic colliders such as the Tevatron and the Large Hadron Collider within the context of R-parity violating supersymmetric model. We have demonstrated the role of these corrections in reducing uncertainties resulting from renormalisation and factorisation scales and thereby making our predictions reliable. We have incorporated soft gluon effects at N 3 LO level in order to study the stability of our results under perturbation. The NNLO corrections are found to be large and significant. The results obtained in this article are also applicable to resonance production of any color-neutral scalar.
121522381
GLUONIC CONTRIBUTIONS TO SPIN-DEPENDENT WEAK STRUCTURE FUNCTIONS: METHOD OF FACTORIZATION
We compute the gluonic contributions to the spin-dependent weak structure functions (i=1, 3, 4), using the factorization theorem in the minimal subtraction scheme, . We have considered the most general case where the quark flavor masses are distinguished and the gluons are off mass shell. The gluonic contribution to the first moment of is found to vanish and do not receive leading order gluonic contribution. These results are shown to be free of mass singularities.
9952561
Testing TeV scale quantum gravity using Dijet production at the Tevatron
Dijet production at the Tevatron including effects of virtual exchanges of spin-2 Kaluza-Klein modes in theories with large extra dimensions is considered. The experimental dijet mass and angular distribution are exploited to obtain stringent limits ( > 1.2 TeV) on the effective string scale MS.
15386012
Searching for signals of minimal length in extra dimensional models using dilepton production at hadron colliders
Theories of quantum gravity suggest the existence of a minimal length scale. It is interesting to speculate what the consequences of the existence of such a length scale would be for models of large extra dimensions, in particular, the ADD model. When ADD model is conflated with the minimal length scale scenario, processes involving virtual exchange of gravitons cease to be ulraviolet divergent. We study the production of dileptons at hadron colliders as an example of a process mediated by virtual gravitons. We find that the bounds we derive on the effective string scale are significantly different (in fact, less stringent) from those derived in the conventional ADD model, both at the upgraded Tevatron and the large hadron collider.
120877004
SO+(n, 1)‐Invariant Finite‐Component Wave Equations and Reflection Invariance
First‐order finite‐dimensional equations of the generalized Bhabha type in a space with n spacelike and one timelike dimensions are considered. It is observed that invariance under the connected part SO+(n, 1) of the pseudo‐orthogonal group in this space requires the use of a wavefunction transforming according to a representation of the larger group SO+(n + 1, 1). It is shown that though the wavefunction [and each part of it obtained by reduction with respect to SO+(n, 1)] transforms into itself under the strong reflection R also, nevertheless the wave equation in an odd‐dimensional space (n + 1 = 2k + 1) may or may not be invariant under R, when the wavefunction employed transforms irreducibly under the connected group SO+(n + 1, 1). Thus, contrary to the suggestion contained in the recent literature, where specific equations are considered, the mere fact of oddness of the dimension of the space does not force the use of representations reducible with respect to the latter group (the matter is represent...
119726764
On the degree of the minimal equation of the matrices in first-order relativistic wave equations
Starting with an analysis of the general structure of the matrix beta 0 entering in first-order relativistic wave equations, the authors show that the degree of the minimal equation of beta 0 is determined by the size and nature of the various spin blocks of the 'skeleton matrix' of the theory. Since it is the numbers of Lorentz irreducible representations contributing to particular spins which determine the sizes of the spin blocks (and the value jm of the maximum spin contained in psi has no direct bearing on these), the reason for the failure of the Umezawa-Visconti rule and its extrapolation by Chandrasekaran et al. (1972) becomes clear. The authors obtain some general results concerning the minimal degree in certain types of theories and on certain procedures whereby the minimal degree can be raised without altering jm, and finally analyse a few interesting examples.
119919377
On mass zero indecomposable representations of the Poincaré group
Considering the space of massless‐particle wavefunctions transforming locally according to the irreducible representation D(m,n) of the homogeneous Lorentz group, we determine explicitly, by a direct and elementary method, the matrices constituting the (reducible but indecomposable) representation of Lorentz transformations with respect to a helicity basis.
120713624
Covariant fields: Poincaré group representations and metric structure in the space of quantum states
The representations of the Poincaré group realized over the space of covariant fields transforming according to any irreducible representationD(m,n) of the Lorentz group are constructed explicitly with reference to a helicity basis. The representation is indecomposable in the massless case. The form of this representation together with the invariance of two-point Wightman functions of the field (which follows from a weak set of axioms) determines the metric structure in the space of quantum states of the field. This structure is explicitly determined for generalD(m,n). Certain particular cases (especially the symmetric traceless tensor field) are discussed in detail. Finally we consider the representation pertaining to massive fields, and examine the passage to the limit of vanishing mass. We present a limiting procedure which leads from the unitary representation of the massive field to the indecomposable non-unitary representation of the massless field.
124211973
Stationary states of a spin-1 particle in a homogeneous magnetic field
We present a simple and complete determination of the energy spectrum and eigenfunctions of a relativistic spin-1 particle with arbitrary magnetic moment in a homogeneous magnetic field. The particle is described by a four-vector field satisfying the usual second-order equation including anomalous-magnetic-moment interaction. In the light of our results and those pertaining to the case when the external field is a Coulomb field, we discuss briefly the question of consistency of the vector theory at the basic c-number level.