121500354
Gluonic corrections to spin dependent weak structure functions
We compute gluonic corrections to the spin dependent weak structure functions g1, g3 and g4. g1WP is found o be directly proportional to the singlet part of g1μP and is ∑i(Δqi + Δqi−αsΔg/2π). In the gluon sector, g3 and g4 are both free from infrared and collinear divergences since they do not receive any gluonic corrections. Hence the Callan-Gross relation in the weak sector is nor corrected by the g→q, q subprocess. g3WP measures Δuv + Δdv. The distribution functions are identified with corresponding OPE matrix elements.
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.
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.
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.
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.
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.
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...
121001129
Arbitrary spin fields: Spectral representations for the two-point functions, and the connection between spin and statistics
Two-point Wightman functions of arbitrary finite component relaticistic fields (which may in general be reducible under the homogeneous Lorentz group) are related to those involving auxiliary fields transforming according to representations of the type D(j, 0), and explicit representations are obtained on the basis of the usual axioms. Our construction does not require the choice of any special kind of basis for the physical states. Using the spectral representations and the weak local commutativity condition a general proof is given for the spin-statistics connection. Special problems which arise in the case of reducible fields are discussed.
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.
118460186
A quantum-mechanically solvable nonpolynomial Lagrangian with velocity-dependent interaction
SummaryThe quantum-mechanical problem of the nonlinear oscillator with the Lagrangian L= 1/2 [x2-k0x2)/(l-λx2)] is solved exactly and the energy levels and eigenfunctions are obtained completely. This model (whenk0=0) is the zero-space-dimensional isoscalar analogue of the nonlinearSU2⊗ SU2 chirally invariant Lagrangian in the Gasiorowicz-Geffen co-ordinates and may also be considered as a modified version of the anharmonic-oscillator and Lee-Zumino models. The bound-state energy levels are found to have a linear dependence on the coupling parameter, in sharp contrast to the case of the familiar oscillator With quartic anharmonicity where the energy, as a function of λ, has complicated singularities at λ = 0. We investigate how far certain standard approximation procedures reproduce the exact results. The Bohr-Sommerfeld quantization procedure is found to reproduce the form of the boundstate energy levels correctly. Interestingly a perturbation-theoretic treatment also reproduces the correct results at least up to the order (λ2) to which we have carried our calculations.RiassuntoSi risolve esattamente il problema della meccanica quantistica dell’osoillatore non lineare con lagrangianoL = 1/2 [(x2-k0x2)/(l-λx2)] e se ne ottengono completamente le autofunzioni e i livelli energetici. Questo modello (quandok0 = 0) è l’analogo isoscalare con dimensione spaziale nulla del lagrangiano chiralmente invarianteSU2 ⊗ SU2 non lineare nelle coordinate di Gasiorowicz-Greffen e si può anche considerare come una versione modificata dei modelli dell’oscillatore anarmonico e di Lee-Zumino. Si trova che i livelli energetici di stato legato dipendono linearmente dal parametro di accoppiamento, in evidente contrasto con il caso familiare di oscillatore con anarmonicità del quart’ordine in cui l’energia, espressa in funzione di λ, presenta complicate singolarità per λ = 0. Si cerca di vedere sino a che punto certi procedimenti standard di approssimazione riproducono i risultati esatti. Si trova che il metodo di quantizzazione di Bohr-Sommerfeld riproduce correttamente la forma dei livelli di energia degli stati legati. È interessante che anche un trattamento con la teoria delle perturbazioni riproduca correttamente i risultati almeno fino all’ordine (λ2) al quale si sono spinti i calcoli.РезюмеТочно решается квант овомеханическая проблема нелинейног о осциллятора с Лагранжианом 

$$L = \frac{1}{2}\left[ {(x^2 - k_0 x^2 )/\left( {1 - \lambda x^2 } \right)} \right]$$

. Полу чены уровни энергии и собственные функции. Эта модель (когда k0=0) представляет изоска лярный аналог с нулевой пространст венной размерностью для нелинейногоSU2⊗SU2, ки рально инвариантного Лагра нжиана в координатах Газиоровича-Геффена и может рассматриват ься как модифицированны й вариант ангармонич еского осциллятора и моделей Ли-Зумино. Обн аружено, что энергети ческие уровни связанных сос тояний имеют линейную завис имость от параметра с вязи в противоположность с лучаю обычного осциллятор а с квадратичной ангармоничностью, дл я которого энергия, как функция Л, имеет си нгулярность при λ=0. Мы исследуем, насколько процедуры стандартных приближ ений воспроизводят т очные результаты. Получено, что процедура квантования Бора-Зом мерфельда правильно воспроизводит форму энергетических уровней свазанных со стояний. Интересно от метить, что в теории возмущений также получаются пра вильные результаты, п о крайней мере, до порядка (λ2), в ко тором мы производили наши в ычисления.