Changes between Version 8 and Version 9 of MUED
 Timestamp:
 11/10/10 10:09:49 (9 years ago)
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MUED
v8 v9 9 9 === Description of the model & references === 10 10 11 One popular ap roach to solve the Hierarchy Problem of the Standard Model is to extend spacetime to higher dimensions. In this framework, the usual fourdimensional spacetime is contained in a fourdimensional brane embedded in a large structure with N additional dimensions, the bulk.11 One popular approach to solve the Hierarchy Problem of the Standard Model is to extend spacetime to higher dimensions. In this framework, the usual fourdimensional spacetime is contained in a fourdimensional brane embedded in a large structure with N additional dimensions, the bulk. 12 12 13 Here, we shall focus on the Universal Extra Dimensional theory, in which the usual Standard Model particles are free to propagate in the bulk. As a consequence, these particles will be seem on the effective theory as a tower of N 4dimensional particles with the same quantum numbers, but with increasing masses. This is called the KaluzaKlein tower. Momentum conservation in the 5dimensional spacetime generates a conserved KaluzaKlein number, which implies that different KaluzaKlein modes can not mix with each other.13 Here, we shall focus on the Universal Extra Dimensional theory, in which the usual Standard Model particles are free to propagate in the bulk. As a consequence, these particles will be seem on the effective theory as a tower of N 4dimensional particles with the same quantum numbers, but with increasing masses. This is called the KaluzaKlein tower. Momentum conservation in the 5dimensional spacetime generates a conserved KaluzaKlein number, which implies that different KaluzaKlein modes can not mix with each other. 14 14 15 In this implementation, a theory with five dimensions is considered, in which the fifth dimension is spatial and compactified on a S1/Z2 orbifold of radius R. We start from the most general fivedimensional Lagrangian. FeynRules derives the fourdimensional lagrangian automatically by imposing dimensional reduction and integrati g out the extracoordinate y.15 In this implementation, a theory with five dimensions is considered, in which the fifth dimension is spatial and compactified on a S1/Z2 orbifold of radius R. We start from the most general fivedimensional Lagrangian. FeynRules derives the fourdimensional lagrangian automatically by imposing dimensional reduction and integrating out the extracoordinate y. 16 16 17 17 The minimal Universal extra dimensional model is given in: … … 47 47 In order to validate our implementation, we have checked 118 processes using a centerofmass energy of 1400 GeV. It was done the following way: 48 48 * '''Comparison of the builtin Madgraph StandardModel and FeynRules generated''' '''Madgraph''' '''MUED for Standard Model''' '''processes.''' This comparison was done using squared matrix element at given phasespace points. 49 * '''Comparison of the existing''' '''CalcHEP''' '''MUED (CHST) with the FeynRules generated ones in''' '''CalcHEP''' *,*'''Madgraph''' '''and Sherpa: CHFR, MGFR and SHFR,''' through the calculation of several '''2to2''' crosssections. All the checks performed were conclusive.49 * '''Comparison of the existing''' '''CalcHEP''' '''MUED (CHST) with the FeynRules generated ones in''' '''CalcHEP''', '''Madgraph''' '''and Sherpa: CHFR, MGFR and SHFR,''' through the calculation of several '''2to2''' crosssections. All the checks performed were conclusive. 50 50 51 * Validation Table  SM + Fermions (Cross sections given in pb): ValidationMUED.jpg51 * Validation Table  SM + Fermions (Cross sections given in pb): [/attachment/wiki/MUED/ValidationMUED.jpg ValidationMUED.jpg] 52 52 53 * Validation Table  Gauge (Cross sections given in pb): ValidationGauge.jpg53 * Validation Table  Gauge (Cross sections given in pb): [/attachment/wiki/MUED/ValidationGauge.jpg ValidationGauge.jpg] 54 54 55 55