arXiv subjects
Publications and source records attributed to I. F. Ginzburg.
Study of charge asymmetry within a neutral system T produced in processes AB\to T X can help solve many problems in particle physics. We collect here some problems, which have been studied well, as well as proposals for future activity with a brief discussion of the main results expected in each case.
1. Discussing 2HDM and Higgs potential, we find the parameters range giving naturally weak effects of CP violation and Flavor Changing Neutral Currents. Within this approach, the widely discussed decoupling limit with heavy $H^\pm$, $H$ and $A$ corresponds to an unnatural set of 2HDM parameters. 2. We define the SM--like scenario as that in which after LHC and e^+e^- LC operations no visible deviations from the minimal SM will be found. We find all the parameter ranges of 2HDM compatible with this scenario. 3. We show that the study of Higgs boson production at Photon Colliders (processes $γγ\to h$ and $e γ\to eh$) can help to distinguish minimal SM from 2HDM with natural set of parameters.
In this report our main attention is focused on the problems which can be solved at Photon Colliders naturally but are hardly solved at LHC and e^+e^- Linear Collider: The New Physics - new particles, new interactions, supersymmetry, Dirac monopole, extra dimensions... SM and the case of a SM--like scenario - EWSB, Higgs bosons, anomalies in interactions of gauge bosons, QCD, Pomeron and odderon... By-product: Production of light Goldstone particles from region of e\toγconversion.
Ultra-peripheral collisions of relativistic heavy ions involve long-ranged electromagnetic interactions at impact parameters too large for hadronic interactions to occur. The nuclear charges are large; with the coherent enhancement, the cross sections are also large. Many types of photonuclear and purely electromagnetic interactions are possible. We present here an introduction to ultra-peripheral collisions, and present four of the most compelling physics topics. This note developed from a discussion at a workshop on ``Electromagnetic Probes of Fundamental Physics,'' in Erice, Italy, Oct. 16-21, 2001.
We discuss the potentialities of the study of CP-odd interactions of the Higgs boson with photons via its production at gamma-gamma and e-gamma colliders. Our treatment of H-gamma-gamma and H-Z-gamma anomalous interactions includes a set of parameters, whose impact on physical observables has not been considered before. We focus on two reactions - gamma+gamma-->H and e+gamma-->eH - and introduce the polarization and/or azimuthal asymmetries that are particularly sensitive to specific features of anomalies. We discuss the ways of disentangling effects of physically different parameters of anomalies and estimate what magnitude of CP violating phenomena can be seen in these experiments.
We discuss how the evasive Odderon signal can be enhanced by final state interactions. We suggest the charge asymmetry of pion spectra in diffractive pi+pi- photoproduction as a promising signature of the Odderon exchange.
The TESLA Technical Design Report Part III: Physics at an e+e- Linear Collider
We review the most important topics and objectives of the physics program of the gamma-gamma, gamma-electron collider (photon collider) option for an e+e- linear collider.
The study of the charge asymmetry of produced particles allows to investigate the interference of different production mechanisms and to determine new features of the corresponding amplitudes. In the process $e^- e^+ \to e^- e^+ π^+ π^-$ the two-pion system is produced via two mechanisms: two-photon (C-even state) and bremsstrahlung (C-odd state) production. We study the charge asymmetry of pions in a differential in the pion momenta cross section originating from an interference between these two mechanisms. At low effective mass of dipions this asymmetry is directly related to the s- and p-phases of elastic $ππ$ scattering. At higher energies it can give new information about the $f_0$ meson family, $f_2(1270)$ meson, etc. The asymmetry is expressed via the pion form factor $F_π$ and helicity amplitudes $M_{ab}$ for the subprocess $γ^*γ\to π^+π^-$ as $\sum G_{ab}{\rm Re}(F_π^*M_{ab})$ where we have calculated analytically the coefficients $G_{ab}$ for the region giving the main contribution to the effect. Several distributions of pions are presented performing a numerical analysis in a model with point-like pions. In the region near the dipion threshold the asymmetry is of the order of 1%. We show that with suitable cuts the signal to background ratio can be increased up to about 10%.
If next generations of heavy quarks and leptons exist within the standard model (SM), they can manifest themselves in Higgs boson production at the Tevatron and the LHC, before being actually observed. This generation leads to an increase of the Higgs boson production cross section via gluon fusion at hadron colliders by a factor 6-9. So, the study of this process at the Tevatron and LHC can finally fix the number of generations in the SM. Using the $WW^*$ Higgs boson decay channel, the studies at the upgraded Tevatron will answer the question about the next generation for mass values 135 GeV $\lsim M_H\lsim 190$ GeV. Studying the $τ\barτ$ channel we show its large potential for the study of the Higgs boson at the LHC even in the standard case of three generations. At the Tevatron, studies in this channel could explore the mass range 110-140 GeV.
The luminosity distribution in the effective $γγ$ mass at photon collider has usually two peaks which are well separated: high energy peak with mean energy spread 5-7% and wide low energy peak.The low energy peak depends strongly on details of design it is unsuitablefor the study of New Physics phenomena. We find simple approximte form of spectra of collided photons for $γγ$ and $eγ$ colliders wich convolution describes high energy luminosity peak with good accuracy in the most essential preferable region of parameters.
We discuss the potentialities of the non-standard interaction study via the Higgs boson production at photon ($\ggam$ and $eγ$) colliders. We estimate the scale of New Physics phenomena beyond the standard model that can be seen in the experiments with Higgs boson production. In particular, the effect of new heavy particles within the standard model is shown to be quite observable.
If a heavy Dirac monopole exists, the light-to-light scattering below the monopole production threshold is enhanced due to strong coupling of monopoles to photons. At the next Linear Collider with electron beam energy 250 GeV this photon pair production could be observable at monopole masses less than 2.5-6.4 TeV in the $e^+e^-$ mode or 3.7-10 TeV in the $γγ$ mode, depending on the monopole spin. At the upgraded Tevatron such an effect is expected to be visible at monopole masses below 1-2.5 TeV. The strong dependence on the initial photon polarizations allows to find the monopole spin in experiments at $e^+e^-$ and $γγ$ colliders. We consider the $Zγ$ production and the $3γ$ production at $e^+e^-$ and $pp$ or $p\bar{p}$ colliders via the same monopole loop. The possibility to discover these processes is significantly lower than that of the $γγ$ case.
Dimuonium (the bound system of two muons, $μ^+μ^-$-atom) has not been observed yet. In this paper we discuss the electromagnetic production of dimuonium at RHIC and LHC in relativistic heavy ion collisions. The production of parastates is analyzed in the equivalent photon approximation. For the treatment of orthostates, we develop a three photon formalism. We determine the production rates at RHIC and LHC with an accuracy of a few percent and discuss problems related to the observation of dimuonium.
If a heavy Dirac monopole exists, the light to light scattering below the monopole production threshold is enhanced due to the strong coupling of monopoles to photons. This effect could be observable in the collision of virtual photons at proton colliders. At the Tevatron it will be seen as pair production of photons with energies 200--400 GeV and roughly compensated transverse momenta 100--400 GeV/c. This effect could be seen at monopole masses about 1--2.5 TeV at the upgraded Tevatron and 7.4--19 TeV at LHC depending on monopole spin.
A Higgs boson within the mass range $M_H=140-190$ GeV can be discovered at a photon collider in the reaction $γγ\to WW$ (with real or virtual W) with the luminosity integral about 1 fb$^{-1}$. The reasonable resolution in the effective mass of the WW system is required.
We consider two coupled problems. We study the dependence on photon virtuality $Q^2$ for the semihard quasi--elastic photoproduction of neutral vector mesons on a quark, gluon or real photon (at $s\gg p_{\bot}^2,\;Q^2; \; p_{\bot}^2\gg μ^2 \approx (0.3$ GeV)$^2$). To this end we calculate the corresponding amplitudes (in an analytical form) in the lowest nontrivial approximation of perturbative QCD. It is shown that the amplitude for the production of light meson varies very rapidly with the photon virtuality near $Q^2=0$. We estimate the bound of the pQCD validity region for such processes. For the real incident photon the obtained bound for the $ρ$ meson production is very high. This bound decreases fast with the increase of $Q^2$, and we expect that the virtual photoproduction at HERA gives opportunity to test the pQCD results. The signature of this region is discussed. For the hard Compton effect the pQCD should work good at not too high $p_{\bot}$, and this effect seems measurable at HERA.
We study the dependence on photon virtuality $Q^2$ for the semihard quasi--elastic photoproduction of neutral vector mesons on a quark, gluon or real photon (at $s\gg p_{\bot}^2, Q^2; p_{\bot}^2 \gg μ^2 \approx (0.3$ GeV)$^2$). To this end we calculate the corresponding amplitudes (in an analytical form) in the lowest nontrivial approximation of the perturbative QCD. The amplitudes for the production of mesons consisting of light quarks vary very rapidly with the photon virtuality near $Q^2=0$. We estimate the bound of the pQCD validity region for such processes. For the process with mass shell photon the obtained bound is very high, and this region seems beyond opportunities of real experiment. This bound decreases fast with the increase of $Q^2$, and we expect that the virtual photoproduction at HERA provides the opportunity to test the pQCD results. The signature of this region is discussed.