119185858
Neutral triple electroweak gauge boson production in the large extra-dimension model at the LHC
We study the prospects of probing large extra dimension model at the LHC through neutral triple gauge boson production processes. In theories with extra dimensions these processes result from the exchange of a tower of massive graviton modes between the SM particles. We consider \gamma\gamma\gamma, \gamma \gamma Z, \gamma Z Z and ZZZ production processes, and present our results for various kinematic distributions at the LHC for \sqrt{S}=14 TeV.
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.
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.
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.
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.
120046449
Evaluation of the density matrix for an ensemble of anharmonic oscillators by a path integral approach
Considering the Feynman path integral representation for the configuration-space density matrix for an ensemble of anharmonic oscillators, we determine the ‘stationary paths’ near which the integrand remains stationary. By taking the path integral to be saturated by contributions from the neighborhood of the path which maximizes the integrand we evaluate the density matrix explicitly in analytic form. This seems to be the first such evaluation of a path integral for a system not describable by a quadratic Hamiltonian. We also comment briefly on the question of analyticity with respect to the perturbation parameter.
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.
120364020
Causality and indefiniteness of charge in spin 3/2 field theories
The possibility of retaining causality of propagation of classical spin 3/2 fields in the presence of an external electromagnetic interaction is investigated. It is shown that in the case of the mixed spin 3/2-spin 1/2 theory of Bhabha and Gupta, causality in the interacting situation may be retained by giving up the positive definiteness of the free total charge and making an appropriate choice of the arbitrary parameters appearing in the Bhabha-Gupta Lagrangian. The authors demonstrate that the causal spin 3/2 equation proposed recently by Fisk and Tait (see abstr. A22979 of 1973) also shares the same feature, namely the indefiniteness of the free total charge.
123041317
Indecomposability of poincare-group representations over massless fields, and the quantization problem for electromagnetic potentials
Considering the little group of the Poincare group associated with a lightlike four-vector, we determine explicitly, in global form, the representation of this little group over the space of covariant massless fields transforming according to some irreducible representation D (m,n) of the homogeneous Lorentz group. The little-group representation is indecomposable and nonunitary. Exploiting the knowledge of this representation for D (½, ½) (i.e., vector fields), we prove that the vector transformation property of the electromagnetic potentials A μ together with the invariance of their two-point Wightman functions (in momentum space) make it impossible to have any nontrivial scheme of quantization in which the metric is positive-definite or even semidefinite. The proof does not involve any axioms beyond those required for the definition and invariance of the Wightman functions; in particular, we do not assume the spectral condition, local commutativity, or any equations of motion or constraint.
18827201
Comments on the ERA-2005 numerical theory of Earth rotation
Two papers recently published in Celestial Mechanics (Krasinsky 2006, and Krasinsky and Vasilyev 2006) have presented a model for Earth-rotation variations, called ERA-2005, based on numerical integration of a new set of equations for the rotation of a deformable Earth followed by a fit of the results of the integration to VLBI data. These papers claimed that this model was superior to any other existing model. The purpose of this Note is to bring to light fundamental errors in the derivation of the basic equations of the new theory, compounded by serious deficiencies in the process of fitting to the data; they make ERA-2005 unsuitable for consideration as a geophysics-based model of nutation and precession.