Related papers: Three Jet Events and New Strong Couplings at LEP a…
Higher-dimensional multi-gluon interactions affect essentially all effective Lagrangian analyses at the LHC. We show that, contrary to common lore, such operators are best constrained in multi-jet production. Our limit on the corresponding…
We list all possible dimension-six CP-conserving $SU_c(3)\times SU_L(2) \times U_Y(1)$ invariant operators involving the third-family quarks which could be generated by new physics at a higher scale. Expressions for these operators after…
In quark-antiquark pair production at LEP, many features of the hadronic final state can be predicted by QCD. Using data collected by the OPAL experiment, we present the statistical distributions of fourteen "event shape observables," which…
Multi-hadronic events produced in e+e- collisions provide an excellent laboratory to study QCD, the theory of strong interactions, and in particular to determine the strong coupling parameter alpha_s and demonstrate its predicted behavior…
We show how to detect and disentangle at the upgraded Tevatron and at LHC, the effects of the three purely gluonic $dim=6$ $SU(3)\times SU(2) \times U(1)$ CP-conserving and CP-violating gauge invariant operators $\ol{\O}_{DG}$, $\O_G$ and…
In an effective Lagrangian approach to physics beyond the Standard Model, it has been argued that imposing $SU(2) \times U(1)$ invariance severely restricts the discovery potential of future colliders. We exhibit a possible way out in an…
We analyze the potential of the CERN Large Hadron Collider to study anomalous quartic vector--boson interactions through the production of vector--boson pairs accompanied by jets. In the framework of $SU(2)_L \otimes U(1)_Y$ chiral…
New Physics that becomes relevant at some high scale $\Lambda$ beyond the experimental reach, can be described in the effective theory approach by adding higher-dimensional operators to the Standard Model (SM) Lagrangian. In Higgs pair…
In a bottom-up approach we investigate lepton-flavour violating processes $\tau \to 3 \ell$ that are mediated by New Physics encoded in effective-theory operators of dimension six. While the opportunity to scrutinize the underlying operator…
We listed all possible dimension-six CP-violating $SU_c(3)\times SU_L(2)\times U_Y(1)$ invariant operators involving the third-family quarks, which can be generated by new physics at a higher energy scale. The expressions of these operators…
We present sensitivity limits on the coefficients of a dimension-6 effective Lagrangian that parametrizes the possible effects of new physics beyond the Standard Model. Our results are based on the study of the process $e^+ e^- \to W^+ W^-…
Precision studies of QCD at $e^+e^-$ colliders are based on measurements of event shapes and jet rates. To match the high experimental accuracy, theoretical predictions to next-to-next-to-leading order (NNLO) in QCD are needed for a…
In this paper we study the effect of new physics contributions to the top quark pair production ($t\bar{t}$) in a possible future linear collider, such as the International Linear Collider (ILC). The use of a dimension-six gauge invariant…
The effective Lagrangian for the seesaw model is derived. Besides the usual dimension-5 operator responsible for light neutrino masses, a dimension-6 operator is included which, for three or less heavy neutrino generations, provides a…
Recently a lot of progress has been made towards a full classification of new physics effects in Higgs observables by means of effective dimension six operators. Specifically, Higgs production in association with a high transverse momentum…
Next-to-leading order calculation for three jet heavy quark production in e^+e^- collisions, including complete quark mass effects, is reviewed. Its applications at LEP/SLC are also discussed.
Three-jet event-shape distributions can be exploited to investigate the dependence of hadronisation effects on the colour and the geometry of the underlying hard event. We present here the first comparison of data in e+e- annihilation and…
Anomalous self-interactions of non-abelian gauge fields can be described by higher dimensional operators featuring gauge-invariant combinations of the field strengths. In the case of QCD, the gluon self-interactions start to be modified at…
Six--jet events via WW pairs, $e^+e^- \ar W^+W^- \ar q_1 \overline{q_1} q_2 \overline{q_2} g g$ are studied at tree level using helicity amplitudes. This is the dominant production mechanism for six--jet final states at Lep II energy. ISR…
Experimental results on jet physics at LEP and SLC are reviewed and compared with perturbative QCD predictions. The discussion includes determinations of the strong coupling $\as$, measurements of event shape distributions and jet cross…