119672029
Working group report: Quantum chromodynamics
This is the report of the QCD working sub-group at WHEPP-8 which was part of the QCD and QGP working group. Discussion and work on some aspects of resummation and parton distribution are reported.
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.
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.
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.
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.
120662802
Commutation relations among members of internal-symmetry multiplets
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.
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.
120399594
A simple accurate formula for the energy levels of oscillators with a quartic potential
Abstract In this note we present a simple analytical formula which reproduces the energy eigenvalues Ek(λ) of the pure quartic and quartic anharmonic oscillators with high accuracy for all values of the anharmonicity parameter λ and the level number k.