18395362
QCD prerequisites for extra dimension searches
For the dilepton production at hadron collider in TeV scale gravity models, inclusion of QCD corrections to NLO stabilises the cross section with respect to scale variations. The K-factors for the various distributions for the ADD and RS model at both LHC and Tevatron are presented.
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.
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.
54538817
Quark and gluon spin-2 form factors to two-loops in QCD
A bstractWe present complete two-loop radiative corrections to the graviton-quark-antiquark form factor G∗ → q$ \overline{q} $ and graviton-gluon-gluon form factor G∗ → g g in SU(N) gauge theory with nf light flavours using d-dimensional regularisation to all orders in ε = d − 4. Thisisanimportantingredienttonext-to-next-to-leadingorderQCDcorrections to hadronic scattering processes in models with large extra-dimensions where Kaluza-Klein graviton modes couple to Standard Model fields. We show that these form factors obey Sudakov integro-differential equation and the resulting cusp, collinear and soft anomalous dimensions coincide with those of electroweak vector boson and gluon form factors. We also find the universal behaviour of the infrared singularities in accordance with the proposal by Catani.
119114678
Diphoton production in the ADD model to NLO + parton shower accuracy at the LHC
A bstractIn this paper, we present the next-to-leading order predictions for diphoton production in the ADD model, matched to the HERWIG parton shower using the MC@NLO formalism. A selection of the results is presented for d = 2–6 extra dimensions, using generic cuts as well as analysis cuts mimicking the search strategies as pursued by the ATLAS and CMS experiments.
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.
121160610
COVARIANT THEORY OF THE QUANTIZED ELECTROMAGNETIC FIELD WITH ONLY PHYSICAL PHOTONS.
A manifestly covariant procedure for quantization of the electro-magnetic potentials Amu is presented, wherein only two types of photons with space-like polarization vectors find a place. The non-appearance of unphysical photons corresponding to the longitudinal and scalar photons of other formulations is due to our insistence from the beginning that the Lorentz condition be satisfied (as an operator equation) by the Amu , and it makes the introduction of any indefinite metric unnecessary. The authors theory therefore leads to the same results in quantum electrodynamics as earlier formulations, but in a manifestly Lorentz covariant and gauge invariant fashion and without recourse to concepts like the indefinite metric or any other ad hoc prescriptions.
120479737
Arbitrary‐Spin Wave Equations and Lorentz Invariance
In an earlier paper it was shown that invariance of the arbitrary‐spin wave equation i(∂ψ/∂t) = Hψ [with ψ transforming according to the representation D(0,s)⊕D(s,0) under rotations, T, C, and P, and boosts in the direction of the momentum, permits four infinite classes of solutions for H. Here we show that when invariance under boosts transverse to the momentum also is imposed, just two possible forms for H survive (in the c‐number formalism). When we go over to the q‐number theory, one of these forms leads to a consistent theory for half‐integer spins only and the other for integer spins.
120662802
Commutation relations among members of internal-symmetry multiplets
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...