We study the impact of dimension-six operators on single- and double-Higgs production rates via gluon fusion at the Large Hadron Collider (LHC). If the top-Yukawa coupling is modified by some new physics whose scale is of the TeV scale, its effect changes the cross sections of single-Higgs production $gg\to H$ and double-Higgs production $gg\to HH$ through the top-loop diagram. In particular, double-Higgs production can receive significant enhancement from the effective top-Yukawa coupling and the new dimension-five coupling $t{\bar t}HH$ which are induced by the dimension-six operator. Comparing these results to the forthcoming data at the LHC, one can extract information of the dimension-six operators relevant to the top quark and the Higgs boson.
Single production of t-quarks at the THERA and LinacxLHC based gamma-p colliders via anomalous gamma-u-t and gamma-c-t couplings have been studied. We show that gamma-p colliders will be a powerful tool for searching for the anomalous couplings.
Possible single productions of the fourth standard model family charged leptons via anomalous interactions at the future ep colliders are studied. Signatures of such anomalous processes and backgrounds are discussed in detail.
Possible single productions of the fourth standard model generation neutrino via anomalous interactions at the future ep colliders are studied. Signatures of such anomalous processes and backgrounds are discussed in detail. Discovery limits for neutrino mass and achievable values of anomalous coupling strength are determined.
While it is natural for supersymmetric particles to be well within the mass range of the large hadron collider, it is possible that the sparticle masses could be very heavy. Signatures are examined at a very high energy hadron collider and an very high luminosity option for the Large Hadron Collider in such scenarios.
We examine anomalous ZZH and gammaZH interactions in the process e+e- -> HZ followed by Z -> l+l- at a linear collider. We study the effects of beam polarization, both longitudinal and transverse, in probing these anomalous couplings. We study various correlations constructed out of the initial and final state lepton momenta and the spins of electron and positron. We evaluate the sensitivity of these observables to probe anomalous couplings at the linear collider.
We study the process $e^+e^- \rightarrow W^+W^- γ$ at high-energy $e^+ e^-$ colliders to investigate the effect of genuine quartic $W^+W^-γγ$ and $W^+W^- Zγ$ anomalous couplings on the cross section. Deviations from the Standard Model predictions are quantified. We show how bounds on the anomalous couplings can be improved by choosing specific initial state helicity combinations. The dependence of the anomalous contributions on the collider energy is studied.
We consider possible production of heavy leptons via anomalous interactions at future $ep$ colliders (THERA and LHeC), $e^+e^-$ colliders (ILC and CLIC) and $pp$ collider CERN LHC. The production, backgrounds and signatures of heavy leptons are analyzed. We obtain the upper mass limits of 800 GeV at LHeC, 450 GeV at ILC and 650 GeV at LHC for optimal choices of relevant parameters.
This talk gives a brief introduction to open questions in jet physics and QCD which come to the fore in the high-luminosity regime characterizing the upcoming phase of the Large Hadron Collider and future hadron colliders.
We propose some channels for the possible observation of anomalous interactions of the fourth standard model generation quarks at the Large Hadron Collider based ep and gamma-p colliders. Namely, u_4 (d_4) -> q gamma and u_4 (d_4) -> q Z -> q l^+ l^- decay processes are considered. Signatures for signals and corresponding standard model backgrounds are investigated at both colliders comperatively. The lowest necessary luminosities to observe these processes and the achievable values of the anomalous coupling strengths are determined. It is shown that the gamma-p collider is advantageous compar…
The single production of top quark due to flavor changing neutral current (FCNC) interaction and its decay to bW are studied at CLIC+LHC based gamma-p colliders. We consider both t-c-gamma and t-u-gamma anomalous couplings. The anomalous charm (up) quark anomalous coupling parameter kappa_gamma^c (kappa_gamma^u) can be probed down to 9.5x10^-3 (8.0x10^-3) at a gamma-p collider with sqrt{s_ep}=6.48 TeV and L_int=100 fb^-1.
We point out that a study of event shapes at hadron colliders allows to explore novel aspects of QCD. These studies are today made easier by the development of a program which automates the resummation.
Anomalous chromomagnetic and chromoelectric dipole moments of the top quark may arise from various high scale theories. We carry out a model independent study of such interactions focusing on the limits that can be obtained from current Tevatron data and the improvements that may be possible at the LHC or at a future Linear Collider.
We examine the sensitivity of $e γ$ colliders (based on $e^+ e^-$ linear colliders of c.m. energy 500 GeV) to the anomalous couplings of the Higgs to W-bosons via the process $e^- γ\longrightarrow νW H$. This has the advantage over $e^+ e^-$ collider in being able to dissociate WWH vertex from ZZH. We are able to construct several dynamical variables which may be used to constrain vrious couplings in the WWH vertex.
We consider the production of a single top quark in association with a $W$ boson at LHeC based $γp$ collider. We compute the cross section for the process $γp\rightarrow WtX$ with the anomalous $Wtb$ and $Wtbγ$ couplings. We find that the sensitivities to anomalous couplings of top quark are shown to be comparable, even better than the ones obtained from direct searches at hadron colliders.
A compilation is given of the pair production cross sections for scalar and vector leptoquarks in the kinematic range of the hadron colliders Tevatron and LHC.
I discuss the impact of the the coherent parton radiation on semi-inclusive production of hadrons in deep inelastic scattering at lepton-proton colliders. Such radiation can be consistently described in the $b$-space resummation formalism, which was originally developed to improve theoretical description of production of hadrons at $e^+e^-$ colliders and electroweak vector bosons at hadron-hadron colliders. I present the detailed derivation of the resummed cross section and the energy flow at the next-to-leading order of perturbative QCD. The theoretical results are compared to the experimenta…
The theoretical status of Higgs boson and supersymmetric particle production at hadron colliders is reviewed with particular emphasis on recent results and open problems.
The potential of LC+HERA based gamma-p collider to probe WW-gamma vertex is presented through the discussion of sensitivity to anomalous couplings and p_{T} distribution of the final quark. The limits of -0.16<(kappa-1)<0.14, -0.30<lambda<0.30, at 95% C.L. can be reached with integrated luminosity 100pb^{-1} and they are competitive to projected future limits from other colliders. The results are compared with corresponding ep collider using Weizsacker-Williams Approximation.
We show that a search for $e^+ e^- \to t \bar q$ $(\bar q = \bar c, \bar u)$ events at LEP--2 collider provide a possibility to improve significantly the modern constraints on coupling constants of anomalous $t$--quark interaction via flavor--changing neutral currents.
To provide context for discussions of experiments at future muon colliders, I survey what is known and what will be known about the top quark and the Higgs boson from experiments at hadron colliders.
The top quark could provide very important information for the Standard Model extentions due to its large mass close to the electroweak symmetry breaking scale. In this work, anomalous single top production is studied by using gamma p-->W^{+}b process at the LHeC based gamma p collider. The sensitivity to anomalous coupling kappa/Lambda could be reached down to 0.01 TeV^{-1}.
The energy spectra of the lepton(s) in eebar --> ttbar --> l^{+-}X/ l^+l^- X' at next linear colliders (NLC) are analyzed a model-independent way for arbitrary longitudinal beam polarizations as a general test of possible anomalous top-quark couplings.
This writeup gives an introduction to the theoretical understanding that lies behind automated resummation. It then discusses its applications to hadron-collider event shapes.
We analyze allowed region of muon anomalous magnetic moment (muon $g-2$), satisfying lepton flavor violations, $Z$ boson decays, and collider physics, in a framework of multi-charged particles. Then we explore the typical size of the muon $g-2$, and discuss which modes dominantly affect muon $g-2$.
I survey the characteristics of hadron colliders as tools to investigate top-quark physics and to explore the 1-TeV scale of electroweak symmetry breaking.
We report the calculation of next-to-next-to-leading order (NNLO) QCD corrections in the purely gluonic channel to dijet production and related observables at hadron colliders. Our result represents the first NNLO calculation of a massless jet observable at hadron colliders, and opens the path towards precision QCD phenomenology with the LHC.
We study the flavor-changing decay $h\to τμ$ with $τ=τ^-+τ^+$ and $μ=μ^-+μ^+$ of a Higgs boson at future hadron colliders, namely: a) High Luminosity Large Hadron Collider, b) High Energy Large Hadron Collider and c) Future hadron-hadron Circular Collider. The theoretical framework adopted is the Two-Higgs-Doublet Model type III. The free model parameters involved in the calculation are constrained through Higgs boson data, Lepton Flavor Violating processes and the muon anomalous magnetic dipole moment; later they are used to analyze the branching ratio of the decay $h\toτμ$ and to evaluate th…
We discuss theoretical aspects of parton distribution functions for very high energy scattering in relation with upcoming measurements in DIS and hadron-hadron collisions.
The measurement of the Higgs coupling to W bosons is an important program at the international linear collider (ILC) to search for the anomaly in the coupling to the gauge bosons. We study the sensitivity of ILC to the Higgs anomalous coupling to W bosons by using ZH->vvWW* events. In this article, we report the status of the study.
In this talk, I review the T-odd correlations induced by CP violating anomalous top-quark couplings at both production and decay level in the process gg --> t t_bar --> (b mu+ nu_mu) (b_bar mu-nu_mu_bar). In addition I will also focus on experimental sensitivities corresponding to the anomalous couplings at the LHC.
We investigate the production of fourth family up-type quarks using effective lagrangian approach at future lepton-hadron colliders and study the kinematical characteristics of the signal with an optimal set of cuts. We obtain the upper mass limits 500 GeV at THERA and one TeV at Linac $\otimes$ LHC.
The current theoretical understanding of anomalous gauge boson couplings is reviewed, and the direct measurement of these couplings in present and future hadron collider experiments is briefly discussed.
We compute the effects of anomalous gauge-boson couplings at high-energy hadron colliders using next-to-leading order $SU(2) \times SU(2)$ chiral perturbation theory. By comparing the yields from the universal $p^2$ terms with those arising from new physics at order $p^4$, we estimate the sensitivity of the SSC and LHC to the indirect effects of electroweak symmetry breaking.
We review the recent theoretical progress in single-top physics at hadron colliders. Apart from single-top production within the Standard Model we treat certain aspects of single-top production in beyond Standard Model scenarios.
We consider the possibility of observing deviations from the Standard Model gauge-boson self-couplings at a future $500$~GeV $e^+ e^-$ linear collider. We concentrate on the case in which the electroweak symmetry breaking sector is strongly interacting and there are no new resonances within reach of the collider. We find a sensitivity to the anomalous couplings that is two orders of magnitude higher than that achievable at LEP II. We also show how a polarized electron beam extends the reach of the collider, allowing experiments to probe different directions in parameter space.
We present compact analytic expressions for all one-loop helicity amplitudes contributing to ttbar production at hadron colliders. Using recently developed generalised unitarity methods and a traditional Feynman based approach we produce a fast and flexible implementation.
We investigate the discovery potential of Kaluza-Klein gluons as a dijet resonance at hadron colliders with different center-of-mass energies, from 14 TeV to 33 TeV to 100 TeV. We also present the current bounds from dijet searches at UA2, Tevatron, and LHC.
We present here the results for Higgs and Supersymmetry prospective searches at the Large Hadron Collider. We show that for one year at high luminosity, Standard Model and MSSM Higgs should be observed within the theoretically expected mass range. MSUGRA and restricted phenomenological MSSM searches lead to discovery of up to 2.5 TeV squarks and gluinos.
Chromomagnetic and chromoelectric dipole interactions of the top quark are studied in a model independent framework. Limits are set on the scale of new physics that might lead to such contributions using available Tevatron data. Prospects at the LHC are reviewed.
We compute the pair production cross section of two Kaluza Klein modes in the Randall-Sundrum model at $e^+e^-$ and hadron hadron colliders. These processes are interesting because they get dominant contribution from the graviton interaction at next to leading order. Hence they provide a nontrivial test of the low scale gravity models. All the Feynman rules at next to leading order are also presented. These rules may be useful for many phenomenological applications including the computation of higher order loop corrections.
The International Linear Collider (ILC) will be able to precisely measure the electroweak couplings of the top in e+e- -> tt~. We compare the limits which can be achieved at the ILC with those which can be obtained in tt~gamma$ and tt~Z production at the Large Hadron Collider (LHC).
The quartic Higgs self-coupling is the final measurement in the Higgs potential needed to fully understand electroweak symmetry breaking. None of the present or future colliders are known to be able to determine this parameter. We study the chances of measuring the quartic self-coupling at hadron colliders in general and at the VLHC in particular. We find the prospects challenging.
At a high energy $ep$ collider, such as the Large Hadron-Electron Collider (LHeC) which is being planned at CERN, one can access the $WWγ$ vertex exclusively in charged current events with a radiated photon, with no interference from the $WWZ$ vertex. We find that the azimuthal angle between the jet and the missing momentum in each charged current event is a sensitive probe of anomalous $WWγ$ couplings, and show that for quite reasonable values of integrated luminosity, the LHeC can extend the discovery reach for these couplings beyond all present experimental bounds.
In this work we seek to compute precisely the rate at which these Higgs particles are produced as a function of the transverse momentum and the rapidity at the Large Hadron Collider. This calculation is carried out to next leading order in the QCD strong coupling $α_s$. In particular, this calculation includes the dominant gluon-initiated mechanism, which is responsible for the majority of the cross section. We work in the infinite top mass approximation, and argue that this is very precise in the domain of applicability.
The theoretical status of squark and gluino production at present and future hadron colliders is reviewed. I shall concentrate on the evaluation of SUSY-QCD corrections to the production cross sections and their phenomenological implications.
The production of three electroweak gauge bosons in high-energy $e^+e^-$ collisions offers a window on anomalous quartic gauge boson couplings. We investigate the effect of three possible anomalous couplings on the cross sections for $W^+W^-γ$, $Z^0Z^0γ$ and $Z^0γγ$ productions at LEP2 ($\sqrt{s} = 200$ GeV) and at a future linear collider ($\sqrt{s} = 500$ GeV). We find that the combination of energies and processes provides reasonable discrimination between the various anomalous contributions.
Single production of top quarks at hadron colliders via $gW$ fusion is examined as a probe of possible anomalous chromomagnetic and/or chromoelectric moment type couplings between the top and gluons. We find that this channel is far less sensitive to the existence of anomalous couplings of this kind than is the usual production of top pairs by $gg$ or $q\bar q$ fusion. This result is found to hold at both the Tevatron as well as the LHC although somewhat greater sensitivity for anomalous couplings in this channel is found at the higher energy machine.
The production of a pair of jets with large rapidity separation in hadron-hadron collisions, and of forward jets in deep inelastic scattering, can in principle be used to test the predictions of the BFKL equation. However in practice kinematic constraints lead to a strong suppression of BFKL effects for these processes. This is illustrated using a BFKL Monte Carlo approach.
We studied the dimension-6 leptonic anomalous gauge couplings in the formulation of linearly realized gauge symmetry effective Lagrangian and investigated the constraints on these anomalous couplings from the existed experimental data including LEP2 and $W$/$Z$ boson decay. Some bounds of $O(0.1-10){\rm TeV}^{-2}$ on four relevant anomalous couplings are given by the Z factories. We studied the sensitivity of testing the leptonic anomalous couplings via the process $e^+e^-\rightarrow W^+W^-$ at future $e^+e^-$ linear colliders. We discussed different sensitivities to anomalous couplings at pol…
The dimension-four genuine anomalous quartic couplings are studied in processes of six-fermion production via e+e- collisions. Complete tree-level electroweak calculations are performed including initial-state-radiation and beamstrahlung. The analysis of final-state distributions can be used to find kinematical cuts to enhance the effects of anomalous couplings. For the parameters of the custodial-symmetry-conserving anomalous couplings a sensitivity in the range between 10^{-3} and 10^{-2} can be expected at 1 TeV.
The production of a pair of jets with large rapidity separation in hadron-hadron collisions, and of forward jets in deep inelastic scattering, can in principle be used to test the predictions of the BFKL equation. However in practice kinematic constraints lead to a strong suppression of BFKL effects for these processes. This is illustrated using a BFKL Monte Carlo approach.
We investigate the potential of a high-energy $γγ$ collider to detect an anomalous $\bar t q γ$ coupling from observation of the reaction $γγ\to t\bar q$, $\bar t q$, where $q=c$ or $u$. We find that with $b$-tagging and suitable kinematic cuts this process should be observable if the anomalous coupling $κ/Λ$ is no less than about 0.05/TeV, where $Λ$ is the scale of new physics associated with the anomalous interaction. This improves upon the bound possible from observation of top decays at the Tevatron.
We review the TeV scale $B-L$ extension of the Minimal Supersymmetric Standard Model (BLSSM) where an inverse seesaw mechanism of light neutrino mass generation is naturally implemented and concentrate on its hallmark manifestations at the Large Hadron Collider (LHC).
