R. Ciftci
Excited quark production at future $γp$ colliders is studied. Namely, $γp \to q^{*}X$ with subsequent $q^{*}\to gq$ and $γq $ decay channels are considered. Signatures for discovery of the excited quark and corresponding standard model backgrounds are discussed in detail. Discovery limits for excited quark masses and achievable values of compositeness parameters $f_s$, $f$ and $f^\prime $ are determined.
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We study the potential of the linear collider (LC) with sqrt{s}=0.5 TeV, linac-ring type ep collider (LCxLHC) with sqrt{s}=3.74 TeV and the large hadron collider (LHC) with sqrt{s}=14 TeV to search for excited neutrinos through transition magnetic type couplings with gauge bosons. The excited neutrino signal and corresponding backgrounds are studied in detail to obtain accessible mass limits and couplings for these three types of colliders.
In the framework of diquark model for production we discuss the yields and observation prospects for excited states of doubly heavy baryons at LHC kinematic conditions.
We analyze the potential of TESLA and CLIC based electron-photon colliders to search for excited spin-1/2 electrons. The production of excited electrons in the resonance channel through the electron-photon collision and their subsequent decays to leptons and electroweak gauge bosons are investigated. We study in detail the three signal channels of excited electrons and the corresponding backgrounds through the reactions e gamma --> e gamma, e gamma --> eZ and e gamma --> nu W. Excited electrons with masses up to about 90% of the available collider energy can be probed down to the coupling f=f'…
The possibility of single and pair excited neutrino production in high energy e+e-, gamma-e and gamma-gamma collisions on linear colliders is studied. The integrated cross sections of these subproceses are calculated. Special attention is paid to search for excited neutrino in e-gamma --> W- W+ e process. Lower limits for the compositeness parameter estimated which will be available on the experiments at VLEPP, SLAC, JLC and DESY future linear colliders.
We study the potential of future high energy e+e- colliders to probe excited neutrino signals in different channels coming from the single production process via gauge interactions. We calculate the production cross section, decay widths and branching ratios of excited spin-3/2 neutrinos according to their effective currents and we compare them with that of the spin-1/2 ones. The signals and corresponding backgrounds are examined in detail to get accessible limits on the masses and couplings of excited spin-3/2 neutrinos.
We analyzed the potential of the LC with $\sqrt{s}=0.5$ TeV, LC$\times$LHC based ep collider with $\sqrt{s}=3.74$ TeV and LHC with $\sqrt{s}=14$ TeV to search for excited electrons through transition magnetic type couplings with gauge bosons. The $e^{\star}\to eγ$ signal and corresponding backgrounds are studied in detail.
It is argued that in the context of TeV gravity with large extra dimensions, excited string states produced in colliders and in the interaction of cosmic rays with the atmosphere may decay preferentially into invisible bulk modes, rather than visible gauge fields on the brane. This contrast to the black hole case comes about because of the absence of a relationship between physical size and temperature for string ball states. We estimate the effect of this upon the number of events predicted at cosmic ray observatories and colliders.
Resonant production of excited $u$ and $d$ quarks at the Future Circular Collider and Super proton-proton Collider have been researched. Dominant jet-jet decay mode has been considered. It is shown that FCC and SppC have great potential for discovery of excited $u$ ($d$) quark: up to 44.1 (36.3) and 58.4 (47.8) TeV masses, respectively. For degenerate case (M$_{u^{\star}}$ = M$_{d^{\star}}$), these values are 45.9 and 60.9 TeV, respectively. This discovery will also afford an opportunity to determine the compositeness scale up to multi-PeV level.
We analyze the potential of the CERN Large Hadron Collider (LHC) to search for excited spin-1/2 electrons and neutrinos. Assuming a SU(2)_L X U(1)_Y invariant model, we study in detail the single production of excited electrons and neutrinos and respective backgrounds through the reactions p p -> e+ e- V and e+- νV with V=photon, W, or Z. We show that the LHC will be able to tighten considerably the direct constraints on these possible new states, probing excited lepton masses up to 1-2 TeV depending on their couplings to fermions and gauge bosons.
We study the single production of excited spin-3/2 and spin-1/2 leptons in future high energy $e^+e^-$ collisions. We calculate the production cross section and decay widths of excited spin-3/2 and spin-1/2 leptons according to their effective currents. We show that these possible new excited states can be probed up to the mass $m^*$ ~ $\sqrt{s}$ depending on their couplings to leptons and gauge bosons. We present the angular distributions of final state particles as a measure to discriminate between an excited spin-3/2 and spin-1/2 lepton signal. The signals and the corresponding backgrounds …
We have investigated the production potential of the spin-1/2 excited muons, predicted by the preonic models, at the four SPPC (Super Proton-Proton Collider)-based muon-proton colliders in different center-of-mass energies. For the signal process μp\rightarrowμ^{\star}X\rightarrowμγX, the production cross-section and the decay width values of the excited muons have been calculated. The pseudorapidity and transverse momentum distributions of the final state particles of muons and photons have been obtained to be determine the kinematical cuts best suited for discovery of the excited muons. By a…
Potential discovery, observation and exclusion limits of excited $u$ and $d$ quarks with gamma+jet final state are researched at the multi-TeV scale colliders, FCC and S$pp$C in this work. Both colliders, FCC and S$pp$C, show that excited $u$ and $d$ quarks could be discovered up to 42.1 TeV and 55.2 TeV for $u^\star$, 30.3 TeV and 39.4 TeV for $d^\star$ and 42.3 TeV and 55.5 TeV mass values for degenerate case (m$_{u^\star}$ = m$_{d^\star}$), respectively. Determination of excited quarks compositeness scale is examined, which will be up to multi-PeV level. Beside these analysis, free paramete…
We study the excited muon production at the FCC based muon-hadron colliders. We give the excited muon decay widths and production cross section. We deal with the $μp\rightarrowμ^{\star}q\rightarrowμγq$ process and we plot the transverse momentum, rapidity and invariant mass distributions of final state particles to get the discovery cuts. By using discovery cuts, we get the mass limits for excited muons. It is shown that the discovery limits on the mass of $μ^{\star}$ are 2.2 TeV, 5.9 TeV and 7.5 TeV for $\mu63$-FCC, $\mu750$-FCC and $\mu1500$-FCC, respectively.
Excited electron production at the SPPC-based ep colliders via contact interactions
本文研究未来基于SPPC的电子-质子对撞机上通过接触相互作用产生自旋1/2激发电子，分析信号与背景，给出发现、观测和排除质量极限及复合尺度最高可达值。
The significant excess recently found by the CDF Collaboration in the inclusive jet cross section for jet transverse energies $E_T \ge 200$ GeV over current QCD predictions can be explained either by possible production of excited bosons (excited gluons, weak bosons, Higgs scalars, etc.) or by that of excited quarks. The masses of the excited boson and the excited quark are estimated to be around 1600 GeV and 500 GeV, respectively.
We study composite electron production at the FCC-based three electron-proton colliders with the center-of-mass energies of $3.46$, $10$ and $31.6$ TeV. For the signal process of $ep\rightarrow e^{\star}X\rightarrow eγX$ , the production cross-sections and decay widhts of the excited electrons have been calculated. The differences of some kinematical quantities of the final state particles between the signal and background have been analyzed. For this purpose, transverse momentum and pseudorapidity distributions of electron and photon have been obtained and the kinematical cuts for discovery o…
In recent years, with the enlightenment of some issues encountered at muon colliders, muon colliders have become more feasible for the high-energy physics community. For this reason, we studied single production of excited muon at muon colliders via contact interaction. Besides, we assumed that the excited muon is produced via contact interactions and decays to the photon and the muon through the gauge interaction. Then, signal and background analyses were performed at the muon anti-muon collider options with 6 TeV, 14 TeV, and 100 TeV center-of-mass energies for the excited muon. Attainable m…
I briefly report on what we can learn about the top quark at hadron colliders.
The dilepton final states, e+e- and mu+mu-, are the most clear channels for new heavy neutral resonances search. Their advantage is that the main irreducible background from the Standard Model Drell-Yan process contributes usually two orders of magnitude lower than the expected signal under the peak region. In this paper we are focused on the search of the excited neutral bosons Z*. At present only the ATLAS Collaboration is looking for such excitations at LHC. We compare our evaluations with the official collaboration results at 7 TeV, and present our estimations at higher centre-of-mass ener…
I review the studies, which were reported after the last Linear Collider Workshop, on top quark physics and QCD physics at a future e+e- linear collider.
The production potential of the excited neutrinos at the FCC-based electron-hadron colliders, namely the ERL60$\otimes$FCC with $\sqrt{s}=3.46$ TeV, the ILC$\otimes$FCC with $\sqrt{s}=10$ TeV, and the PWFA-LC$\otimes$FCC with $\sqrt{s}=31.6$ TeV, has been analyzed. The branching ratios of the excited neutrinos have been calculated for the different decay channels and shown that the dominant channel is $ν^{\star}\rightarrow eW^{+}$. We have calculated the production cross sections with the process of $ep\rightarrowν^{\star}q\rightarrow eW^{+}q$ and the decay widths of the excited neutrinos with…
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 potential of $μ^{+}μ^{-}$ colliders to investigate the fourth SM family fermions predicted by flavour democracy has been analyzed. It is shown that muon colliders are advantageous for both pair production of fourth family fermions and resonance production of fourth family quarkonia. Also isosinglet quarks production at $μ^{+}μ^{-}$ colliders has been investigated.
A review of results on top quark physics expected at the Photon Linear Colliders is presented.
We discuss the prospects to observe effects of transverse polarization and spin-spin correlations of top quark pairs produced at hadron colliders.
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.
Mass spectra of excited meson states consisting of u-, d-quarks and antiquarks with I = 1 are considered. The comparison between the existing experimental data and the mass values evaluated with phenomenological formulae is carried out. Problems of identification of vector and scalar meson excited states are discussed.
The charge form factor and charge radius of neutron are investigated in the perturbative chiral quark model (PCQM) with considering both the ground and excited states in the quark propagator. A Cornell-like potential is extracted in accordance with the predetermined ground state quark wavefunction, and the excited quark states are derived by solving the Dirac equation with the extracted PCQM potential numerically. The study reveals that the contributions of the excited quark states are considerably influential in the charge form factor and charge radius of neutron as expected, and the total re…
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.
Top-quark physics plays an important role at hadron colliders such as the Tevatron collider at Fermilab or the upcoming Large Hadron Collider (LHC) at CERN. Given the planned experimental precision, detailed theoretical predictions are mandatory. In this article we present analytic results for the complete electroweak corrections to gluon induced top-quark pair production, completing our earlier results for the quark-induced reaction. As an application we discuss top-quark pair production at Tevatron and at LHC. In particular we show that, although small for inclusive quantities, weak correcti…
I discuss strategies for probing CP properties in the top quark system at $e^-e^+$ and hadron Colliders. The magnitudes of CP violation effects predicted by various models are reviewed. I also discuss the potential of various current and future colliders in measuring the CP asymmetry associated with the productions and/or decays of the top quarks.
I review the NRQCD factorization approach for quarkonium production and compare its predictions with measurements in hadron-hadron and ep collisions.
In this talk we review some of the most relevant effects that the mixing with a Q=2/3 quark singlet might give at high energy colliders and K and B factories.
The ability of high energy lepton and photon colliders to probe the gauge couplings of the top-quark is summarized.
In this talk, I briefly review several models of the heavy quarkonium production at collider energies, and discuss the status of QCD factorization for these production models.
The Kaluza-Klein excitations of the Higgs bosons of the universal extra dimension model are extremely challenging to detect. We discuss the production and possible detection mechanisms of such excited scalars at the LHC. The dominant production mechanism of such scalars is from the decay of the excited third generation quarks. In particular, the charged Higgs boson has a large production cross-section over most of the parameter space. We highlight how one may detect these excited scalars. We also comment on the production and detection of excited neutral scalars.
We provide a brief overview of some current experimental and theoretical issues of heavy quark production.
L=1 excited heavy baryon masses are analyzed by heavy quark and large N_c expansions. In heavy quark limit, mass is parameterized by Λ-bar and it is expanded further by spin-flavor breaking operators to the zeroth order of 1/N_c. Expanding coefficients will be fixed by more data on the excited baryons in the near future.
The top quark will be extensively studied at future muon colliders. The threshold cross section can be measured precisely, and the small beam energy spread is especially effective at making the measurement useful. We report on all the activities of the top quark working group, including talks on top quark physics at other future colliders.
Spectroscopy of excited quarkonium states in the light-front quark model
本文在LFQM中系统计算粲偶素与底偶素的1S、2S、3S及1P态的电磁形状因子、衰变常数、PDFs和DAs等性质，补足以往缺乏的3S与1P研究。
The current theoretical predictions for the observables related to the top-quark pair and the single-top productions at hadron colliders are briefly reviewed. The theoretical predictions are compared to the experimental measurements carried out at the Tevatron and the LHC.
The theoretical description of heavy quarkonium production at high-energy p-pbar and e-p colliders is reviewed. Predictions based on non-relativistic QCD factorisation are confronted with recent charmonium and bottomonium data from the Tevatron and HERA. Potential shortcomings of the present theoretical analyses are discussed, and the prospects for quarkonium physics at the upgraded Tevatron and HERA colliders and at the LHC are summarised.
Relativistic properties of qqbar potentail, mass spectra of orbitally and radially excited B and D mesons as well as semileptonic decays of B mesons to orbitally excited D mesons are discussed in the framework of the relativistic quark model based on the quasipotential approach.
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.
We discuss the polarization and spin correlations of top quarks produced above threshold at a future linear collider, including QCD radiative corrections.
We interpret the recent ATLAS multi-jet search results using 20.3 fb-1 data at sqrt(s)=8 TeV in the context of searching for excited quarks. Within the effective field theory framework, using the null results of that search, our analysis shows that the excited quark mass below 5 TeV can be excluded at the 95% confidence level. Our analysis also indicates that when the validation of effective field theory is considered, the limit can be largely compromised.
In this note we consider the sensitivity of the Large Hadron Collider (LHC) to the single production of new heavy vector-like quarks. We consider a model with large mixing with the standard model top quark with electroweak production of single heavy top quarks. We consider center of mass energies of 14, 33, and 100 TeV with various pileup scenarios and present the expected sensitivity and exclusion limits.
Heavy quark production is studied at the high energy linear e^+e^- collider (LC) TESLA both in its nominal and Photon Collider (PC) mode. Leading order cross-sections are calculated for the production of heavy quarks, e^+e^- -> e^+e^- Q\bar{Q}X, at high transverse momenta. The sensitivity of this process to the gluon content in the photon is studied.
In a composite model of the weak bosons the excited bosons, in particular the p-wave bosons, are studied. The state with the lowest mass is identified with the boson, which has been discovered recently at the "Large Hadron Collider" at CERN. Specific properties of the excited weak bosons are studied, in particular their decays into weak bosons and into photons.
The azimuthal asymmetry of heavy quarks production on double polarized proton-proton and proton-antiproton colliders are studied in this work at next-to-leading order in $α_s$, with some details included. The purpose is to see whether the effect of extracted transversity distribution functions can be seen on present and near future colliders. All analytic one-loop hard coefficients are given. Numerical results for the asymmetry on proton-(anti)proton colliders are presented.
We examined the single production of fourth family b' quarks at the Large Hadron electron Collider (LHeC).We have analyzed the background and the signal processes for the mass range 300-800 GeV. We find the discovery region for an optimal parametrization of the Vqb' matrix elements.
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.
Heavy quark production in multijet events at $e^+e^-$ colliders is studied at tree level. Total production rates are given and compared with the corresponding results for massless quarks. A new method of computing helicity amplitudes is briefly sketched. Talk presented at the XXIXth Rencontres de Moriond, QCD and High Energy Hadronic Interactions, Meribel, France, March 19-26 1994.
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.
Parity violation induced by the chromo-anapole form factor of the bottom quark, generated from weak corrections, is studied in polarized hadron collisions. The forward-backward asymmetry in the bottom quark pair production at polarized $pp$ and $p\bar{p}$ colliders is evaluated in the Standard Model and in a Two Higgs Doublet Model to examine the effects of parity violation. In the models studied, promising results are found for polarized $p\bar{p}$ 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…
We present a detailed study of the production and decay of the excited quark at the QCD next-to-leading order (NLO) level at the Large Hadron Collider, using the narrow width approximation and helicity amplitudes method. We find that the QCD NLO corrections can tighten the constraints on the model parameters and reduce the scale dependencies of the total cross sections. We discuss the signals of the excited quark production with decay mode $q^{\ast}\rightarrow qγ$ and $q^{\ast}\rightarrow qg$, and present several important kinematic distributions. Moreover, we give the upper limits of the exci…
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.
The study of the properties of the top quark is one of the main goals of the Large Hadron Collider (LHC) physics program. The experimental precision expected at the LHC requires the calculation of several top-quark related observables beyond leading order in the strong coupling constant. In this work we briefly review the status of the theoretical predictions for the top-quark production processes at hadron colliders. Special attention is devoted to recent progress in the calculation of next-to-next-to-leading-order corrections to the top-quark pair production cross section.
The top quark data in the lepton plus $τ$ channel offers a viable probe for the charged Higgs boson signal. We analyse the recent Tevatron collider data in this channel to obtain a significant limit on the $H^\pm$ mass in the large $\tanβ$ region.
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