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.
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.
123141603
Solution of the Fisk-Tait Equation for Spin 3/2 Particles in Interaction with a Homogeneous Magnetic Field
The Fisk--Tait wave equation for spin-3/2 particles, which has been shown to remain causal even with coupling to external fields, is shown to be also free of other types of difficulties by which the Rarita--Schwinger formalism is plagued. Unlike the latter, the Fisk----Tait equation with coupling to a homogeneous magnetic field has no modes with complex frequencies irrespective of the magnetic field strength. We show this by explicit solution of the equation. Further, the invariant scalar product in the Fisk-Tait theory, expressed in terms of the independent components of the wave function, is shown to be unaffected by the presence of the external field. (AIP)
118914003
Wave equations for zero-mass particle with invariant helicities
SummaryWe present a brief discussion of the difficulties associated with taking the limitm→0 in massive-particle equations of the formi(∂ψ/∂t)=Hψ, in which ψ transforms according to theD(0,s)⊕D(s,0) representation of the homogeneous Lorentz group. It is pointed out that, though the HamiltonianH tends to a well-defined form asm→0, the resulting wave equation is still unsatisfactory as the invariant scalar product (in the space of solutions of the wave equation) has an unacceptable form. We observe that this difficulty is due to the indecomposability of the representation of the Poincaré group over wave functions transforming asD(0,s)⊕D(s,0) in the massless case. Making due allowance for this fact we obtain, in close parallel to the treatment for massive particles, wave equations for zero-mass particles with invariant helicities ±s. The relevant invariant scalar products are also determined.RiassuntoSi presenta una breve discussione associata con il limitem→0 in equazioni per particelle con massa della formai(∂ψ/∂t)=Hψ, in cuiψ si trasforma secondo la rappresentazioneD(0,s)⊕C(s,0) del gruppo di Lorentz omogeneo. Si mette in rilievo che, sebbene l’hamiltonianoH tenda ad una forma ben definita quandom→0, l’equazione d’onda risultante non è ancora soddisfacente in quanto il prodotto scalare invariante (nello spazio delle soluzioni dell’equazione d’onda) ha una forma inaccettabile. Si osserva che questa difficoltà è dovuta alla indecomponibilità della rappresentazione del gruppo di Poincaré rispetto alle funzioni d’onda che si trasformano comeD(0,s)⊕D(s, 0) nel caso senza massa. Tenendo dovuto conto di questo fatto si ottengono, in stretta analogia con il trattamento per particelle con massa, equazioni per particelle con massa nulla con elicità invarianti ±s. Si determinano anche i relativi prodotti scalari invarianti.РеэюмеВкратце обсуждаются трудности, воэникаюшие при переходе к пределуm→;0 в уравнениях видаi(∂ψ/∂t)=H у с отличной от нуля массой частиц, в которых ψ преобраэуется согласно представлениюD(0,s)⊕D(s, 0) однородной группы Лорентца. Отмечается, что хотя Гамильтониан Я стремится к хорощо иэвестному выражению приm→0, но окончательное волновое уравнение является неудовлетворит ельным, так как инвариантное скалярное проиэведение (в пространстве рещений волнового уравнения) имеет неприемлемый вид. Мы обнаруживаем, что зта трудность обусловлена неприводимостью представления группы Пуанкаре череэ волновые функции, преобраэуюшиеся, какD(0,s)⊕D(s,0) в случае нулевой массы. Учитывая зтот факт, мы, по аналогии с рассмотрением для частиц с отличной от нуля массой, получаем волновое уравнение для частиц нулевой массы с инвариантными спиральностями ±s. Также определяются соответствуюшие инвариантные скалярные проиэведения.
122581187
On the gauge problem in quantum field theory
122841960
On the energy levels of the anharmonic oscillator
121298874
Dynamics of a nonlinear field
Abstract A systematic study is made of the plane wave modes of a nonlinear c -number field ( λφ 4 model) and interesting features of the behavior of such fields, which do not seem to have been observed before, are brought out. These relate to the case λ lower bound on the energy density in the wave field. The case of fields with higher nonlinearities is briefly considered.