Energy On The Number Of New Physical Phenomena In The Collider Studies

The naissance of the gauge theory is an extremely conspicuous step toward the unification of all kinds of interactions.The Standard Model was born in this background and has obtained enormous success.The present precise experimental data have shown an excellent agreement with the predictions of the Standard Model,which based on the SU(3)(?)SU(2)(?)U(1)gauge theory.But another foundation stone of the SM,the Higgs Mechanism,hasn't been proved yet.However people believe that the SM has only been considered to be an effective theory of some underlying theory in low energy.The Minimal Supersymmetry Standard Model(MSSM),the Large Extra Dimension Model(LED)and the Littlest Higgs Model(LH)have solved the hierarchy problem in different ways,and are widely considered as the most appealing extensions of the Standard Model.The MSSM settles the hierarchy problem by introducing supersymmetry and super particles.It predicts that the new physics beyond the Standard Model will appear at the TeV energy scale.We expect the lighter charginos((?)^±)and neutralinos((?)⁰)to be detected at the Tevatron and the Large Hadron Collider.We also expect all the SM particles' supersymmetric partners and the predicted Higgs bosons to be found.The hierarchy problem can be overcome by adding new dimensions in Large Extra Dimension Model.It's a common thought that the space-time dimensions are larger than 4 in String theory,so the LED can be considered as an effective theory of the String theory. The gravity is involved in this theory,and as Arkani-Hamed,Dimopoulos,and Dvali proposed,the picture of a massless graviton propagating in D dimensions is equivalent with the picture of massive Kaluza-Klein gravitons propagating in 4 dimensions.This makes it possible to study the interaction between the graviton and common SM particles, especially the interaction with Higgs bosons.The cancellations of the quadratic divergence in the Littlest Higgs model occur between particles with the same statistics:divergences due to gauge bosons are canceled by new gauge bosons and similarly for the heavy quarks.One of the most important task of present and future experiments is to search for Higgs boson and investigate its properties. Studying the properties of the Higgs potential will reveal details of mass-generation mechanism in spontaneously broken gauge theories,which can be obtained through measuring the Higgs boson self-interactions.Due to the coupling strength of the top-quark-Higgs Yukawa coupling is proportional to the top-quark mass,the top quark Yukawa coupling g_t(?)his very large and the cross section of t(?)h⁰ will be strongly enhanced.Besides,the top quark and Higgs boson play an important role in the particle physics.Therefore,the t(?)h⁰ associated production can be used to probe this coupling and further test of the predicted models and reveal new physics.One of the most important missions of future high energy experiments is to explore the electroweak symmetry break mechanism and search for predicted particles such as Higgs in SM,Higgs in other expanded models,graviton in Extra Dimension,(?)^±,(?)⁰,etc, predicted in MSSM.To investigate the discovering potential of colliders,not only a proper understanding of the production mechanisms is necessary,but also accurate theoretical predictions of the signature should be provided.In our paper,we have studied several production effects of new physics,including:investigate((?)₂⁰(?)₁^±)associated production process at hardon colliders,one can expect the accuracy of the cross section measurement of the neutralino-chargino((?)₂⁰(?)₁^±)associated production at the upgraded Tevatron can reach few percent.Therefore,for the precise experiments at TeV scale hadron colliders,both the higher order QCD and electroweak corrections should be considered in the theoretical predictions,and thereby one can improve experimental mass bounds and exclusion limits for the new particles.Moreover,the consideration of higher order QCD contributions can reduce the dependence of the cross sections on the renormalization and factorization scales in the LO.And the cross sections in NLO are under much better theoretical control than the leading order estimates.We also studied the t(?)h⁰ associated production processes at linear colliders in the large extra-dimension model and in the Littlest Higgs model and also its extension with T-parity up to NLO.Due to the Yukawa coupling is proportional to the top-quark mass which is very large and might be probed in experiments,the t(?)h⁰ associated production processes are very important.Through the study of the top physics,the Higgs physics and their Yukawa coupling,we can learn their production at the accelerators and further test the models and find new physics.The main innovations in this thesis are listed below:·Different from the traditional method of using a fictitious gluon(photon)mass to regularize the IR singularities,we use the dimensional regularization scheme to cancel and separate the UV divergences and IR singularities when we perform NLO QCD calculations and the full one-loop electroweak calculation.We can easily check the cancellation of IR singularities in the analytic expressions and get finite results. ·I use the Two Cutoff Phase Space Slicing Method to calculate the real gluon emission corrections and the real photon emission corrections.This method is one of the newest and most reliable methods of performing NLO QCD calculations which I also used to treat the full electroweak calculations for the first time.·The((?)₂⁰(?)₁^±)associated production with their possible further decay to trilepton signature might be detected at hadron colliders.The trilepton signature which called "Gold-plated signature" can be the most promising channel for supersymmetric particle searches at hadron colliders.In this thesis,I calculated the((?)₂⁰(?)₁^±)associated production at hadron colliders including NLO QCD and full one-loop electroweak corrections in MSSM.The results of my calculation are the most accurate results of this process so far.My results will be helpful for the experiments at hadron colliders to look for predicted supersymmetry particles.·In this thesis,I calculated a single charged Higgs boson production associated with a bottom-charm pair at CERN Large Hadron Collider.We conclude that the squark mixing mechanism in the MSSM makes the pp→(?)cH^-+X process a new channel for discovering a charged Higgs boson and investigating flavor changing mechanism.I present the most accurate results of this process so far.My calculation will be helpful for the LHC experiments to detect charged Higgs boson and look for physics beyond the Standard Model.·The process of t(?)h⁰ associated production at future colliders is an important instrument in measuring the Yukawa coupling strength.The precise calculation is necessary to distinguish the property of the Yukawa coupling in different models.For the first time we consider the t(?)h⁰ associated production at future linear colliders in both polarized and unpolarized collision modes in order to test the large extra-dimension effects.We also study the corrections to this process up to QCD next-to-leading order in the Littlest Higgs model with and without T-parity for the first time,and further use it to test the models and the LH/LHT effects.