7785355
Getting to the top with extra dimensions
Abstract The prospect of large extra dimensions and an effective theory of gravity at around a TeV has interesting experimental consequences. In these models, the Kaluza–Klein modes interact with Standard Model particles and these interactions lead to testable predictions at present and planned colliders. We investigate the effect of virtual exchanges of the spin-2 Kaluza–Klein modes in the production cross-section of t t pairs at the Tevatron and the LHC and find that the t t cross-section can be an effective probe of the large extra dimensions. This enables us to put bounds on the effective low-energy scale.
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.
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.
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.
120740147
Relativistic wave equations: proper Lorentz invariance and invariance under discrete transformations
Considering the standard form i∂ψ/∂t=Hψ [with ψ transforming according to D(0,s)⊕D(s,0)] of wave equations for free particles of arbitrary spin, we determined in a recent paper the admissible forms of H consistent with invariance of the equation under the Poincare group and under T, C, and P. Here we show that even if T and C invariance is not imposed, the admissible Hamiltonians are the same (apart from one extra possibility H = E). Expressed differently, except for the trivial case H = E, invariance of free‐particle equations under the connected Poincare group and P implies T and C also.
122581187
On the gauge problem in quantum field theory
122841960
On the energy levels of the anharmonic oscillator
118727721
Semi-coherent states of the quantum harmonic oscillator
SummaryIt is shown that there exists for the quantum harmonic oscillator a large class of « semi-coherent » states, which represent harmonically oscillating wave packets whose « spread » or « size » remains constant. These states are different from the coherent states in not having the minimum value 1/2ħ for the uncertainty product Δx·Δp.RiassuntoSi dimostra che esiste per l’oscillatore armonico quantistico una grande varietà di stati « semicoerenti », che rappresentano pacchetti d’onde oscillanti armonicamente, la cui « diffusione » o « dimensione » rimane costante. Questi stati differiscono dagli stati coerenti per non avere il valore minimo 1/2ħ per il prodotto d’indeterminazione Δx·Δp.РезюмеПоказывается, что для квантового гармонического осци ллятора существует б ольшой класс « полукоreр ентньIх» состояний, кот орые предст « полукоreрентньIх» состо яний, которые предста вляют гармони чески осциллирующие волновые пакеты, «разброс » или «разме ры » которых остаются постояннымгармонич ески осциллирующие волновые пакеты, «раз брос » или «размеры » которых остаются постоянными. Эти сост ояния отличаются от к огерентных состояни й тем, что не имеют мини мальной величины Р дл я произве или «размеры » которых остаются постоянными. Эти состояния отлича ются от когерентных с остояний тем, что не им еют минимальной вели чины Р для произведен ия неопределенносте й состояния отличаютс я от когерентных сост ояний тем, что не имеют минимальной величин ы Р для произведения н еопределенностей что не имеют минималь ной величины Р для про изведения неопредел енностей неопределенностей Ах Ар.
120859611
Inconsistencies in the symmetric tensor field description of spin-2 particles in an external homogeneous magnetic field
We present a systematic investigation of the problem of a spin-2 particle, described by a symmetric tensor wave function, moving in a homogeneous magnetic field (h.m.f.). An interaction involving a multiple of the Federbush term, besides the minimal interaction, is considered. By explicit solution of the wave equation with an external h.m.f., we show that the energy spectrum of the spin-2 particle, like that of the spin-3/2 particle (Rarita-Schwinger theory with minimal coupling) spills over into the complex plane. This happens even for arbitrarily small magnetic fields if the coupling is minimal, while the onset of the trouble is delayed till the field strength rises to 2m/sup 2//3e if the Federbush term is included. Our results also throw new light on the problem of the number of constraints, and bring into focus the associated breakdown of Lorentz invariance. We demonstrate that the correct number of constraints exists (irrespective of whether the Federbush term is present or not) if the electromagnetic field is a pure h.m.f.; but the number of constraints is too few for any other electromagnetic field (even one obtainable from a pure h.m.f. by a Lorentz transformation) unless the standard Federbush term is included. The results of ourmore » analysis are discussed in relation to a similar analysis for lower spins as well as their implications for higher-spin theories. (AIP)« less