arXiv subjects

V. A. Khoze

Publications and source records attributed to V. A. Khoze.

At least 163 records · Page 9Linked to original sources

arXiv2001

Non-factorizable corrections and effective field theories

We analyze the structure of higher-order radiative corrections for processes with unstable particles. By subsequently integrating out the various scales that are induced by the presence of unstable particles we obtain a hierarchy of effective field theories. In the effective field theory framework the separation of physically different effects is achieved naturally. In particular, we automatically obtain a separation of factorizable and non-factorizable corrections to all orders in perturbation theory. At one loop this treatment is equivalent to the double-pole approximation (DPA) but generalizes to higher orders and, at least in principle, to beyond the DPA. It is known that one-loop non-factorizable corrections to invariant mass distributions are suppressed at high energy. We study the mechanism of this suppression and obtain estimates of higher-order non-factorizable corrections at high energy.

hep-ph↗

arXiv2001

Rapidity Gap Higgs Signal at the Tevatron and the LHC

We quantify the rate and the signal-to-background ratio for Higgs --> b anti-b detection in double-diffractive events at the Tevatron and the LHC. The signal is predicted to be very small at the Tevatron, but observable at the LHC. We show that the double-diffractive dijet production may serve as a unique gluon factory. This process can be used also as a Pomeron-Pomeron luminosity monitor.

hep-ph↗

arXiv2001

Probabilities of rapidity gaps in high energy interactions

We show that high energy hadronic reactions which contain a rapidity gap and a hard subprocess have a specific dependence on the kinematic variables, which results in a characteristic behaviour of the survival probability of the gap. We incorporate this mechanism in a two-channel eikonal model to make an essentially parameter-free estimate of diffractive dijet production at the Tevatron, given the diffractive structure functions measured at HERA. The estimates are in surprising agreement with the measurements of the CDF collaboration. We briefly discuss the application of the model to other hard processes with rapidity gaps.

hep-ph↗

arXiv2001

Comment on an invisible Higgs boson and 50 GeV neutrino

It has been recently suggested in hep-ph/9911535 and hep-ph/0006324 that the fourth generation of leptons and quarks is not excluded by the precision Z-boson measurements, provided that the mass of the fourth neutrino is around 50 GeV and that its mixing with the neutrinos of the first three generations is negligibly small. We would like to note that in this case the decay rate of the Standard Model Higgs boson into the pair of such neutrinos would be about two orders of magnitude higher than than the Higgs to b-bbar rate. Thus, the predominant decay mode of the Higgs would be invisible, which would require a special strategy for its searches.

hep-ph↗

arXiv2001

Double-diffractive processes in high-resolution missing-mass experiments at the Tevatron

We evaluate, in a model-independent way, the signal-to-background ratio for Higgs -> b bbar detection in exclusive double-diffractive events at the Tevatron and the LHC. For the missing-mass approach to be able to identify the Higgs boson, it will be necessary to use a central jet detector and to tag b quark jets. The signal is predicted to be very small at the Tevatron, but observable at the LHC. However we note that the background, that is double-diffractive dijet production, may serve as a unique gluon factory. We also give estimates for the double-diffractive production of chi_c and chi_b mesons at the Tevatron. We emphasize that a high-resolution missing-mass measurement, on its own, is insufficient to identify rare processes.

hep-ph↗

arXiv2001

High p_T Higgs signal for the LHC

We show that the broad transverse momentum distribution of the Higgs boson produced by WW fusion can provide a viable way to identify H --> b anti-b decays at the LHC, if particular kinematical configurations with large rapidity gaps are selected. We estimate the event rate of the signal and of the QCD b anti-b background. We also discuss Higgs boson detection via the H --> tau tau and H --> WW* decay modes.

hep-ph↗

arXiv2001

Rates for rapidity gap Higgs production

We present model-independent estimates of the signal-to-background ratio for Higgs --> b anti-b detection in double-diffractive events at the Tevatron and the LHC. For the missing-mass approach to be able to identify the Higgs boson, it will be necessary to tag the b quark jets in the central region. The signal is predicted to be very small at the Tevatron, but observable at the LHC. We note that the double-diffractive dijet production, may serve as a unique gluon factory. This process can be used also as a Pomeron-Pomeron luminosity monitor.

hep-ph↗

arXiv2001

The compatibility of diffractive hard scattering in p pbar and ep collisions

We show that the data for diffractive dijet production at the Tevatron p pbar collider are consistent with diffractive deep inelastic e p data collected at HERA. The breakdown of factorization between the two data sets is naturally explained by a strong tendency to populate the rapidity gap in the p pbar diffractive process by secondaries from soft underlying interactions and by bremsstrahlung associated with the presence of the hard dijet subprocess.

hep-ph↗

arXiv2000

Soft diffraction at the LHC and properties of the Pomeron

We briefly describe a model for soft diffraction. The model description of ISR, SppbarS and Tevatron data, and the predictions of the total, elastic, single and double diffractive cross sections at the LHC can be found in the original paper. Here we address issues raised at Diffraction 2000, in particular concerning the nature of the resulting Pomeron trajectory.

hep-ph↗

arXiv2000

Luminosity monitors at the LHC

We study the theoretical accuracy of various methods that have been proposed to measure the luminosity of the LHC pp collider, as well as for Run II of the Tevatron p barp collider. In particular we consider methods based on (i) the total and forward elastic data, (ii) lepton-pair production and (iii) W and Z production.

hep-ph↗

arXiv2000

Radiative Corrections to the Hadronic Cross-Section Measurement at DAPHNE

The hadronic invariant mass distribution for the process of electron-positron annihilation into a pair of charged pions accompanied by a photon radiated from the initial state has been studied for the region of DA$Φ$NE energies. The Born cross-section and the electromagnetic radiative corrections to it are calculated for realistic conditions of the KLOE detector. The dependence on the physical parameters which define the event selection is obtained.

hep-ph↗

arXiv2000

Soft diffraction and the elastic slope at Tevatron and LHC energies: a multi-Pomeron approach

We present a formalism for high energy soft processes, mediated by Pomerons, which embodies pion-loop insertions in the Pomeron trajectory, rescattering effects via a two-channel eikonal and high-mass diffractive dissociation. It describes all the main features of the data throughout the ISR to Tevatron energy interval. We give predictions for soft diffractive phenomena at the LHC energy, and we calculate the different survival probabilities of rapidity gaps which occur in various diffractive processes.

hep-ph↗

arXiv2000

Impact of the W boson decay width on photon bremsstrahlung accompanying W pair production

The bremsstrahlung spectrum of photons accompanying $W$ pair production depends on the decay width of the unstable $W$ bosons. The dependence arises from the interference between emission at different stages of the production and decay process. We present a quantitative discussion of this effect, and consider the implications for measurements at LEP2 and LC energies.

hep-ph↗

arXiv2000

Higgs or dijet production in double rapidity gap events

We quantify the rate of double diffractive Higgs/dijet production at $pp$ (or $p\bar{p}$) colliders. The suppression due to QCD bremsstrahlung is calculated perturbatively up to single $\log$ accuracy. The survival probability of the rapidity gaps is discussed. A first comparison with experiment is made.

hep-ph↗

arXiv2000

Can the Higgs be seen in rapidity gap events at the Tevatron or the LHC?

Double diffractive Higgs production at $pp$ (or $\bar{p}p$) colliders continues to attract attention as a potential signal in the search for the boson. We present improved perturbative QCD estimates of the event rates for both the exclusive and inclusive double diffractive Higgs processes, paying particular attention to the survival probability of the rapidity gaps. We find that the major uncertainty is in the prediction for the survival probability associated with soft rescattering. We show that an analogous process, the double diffractive production of a pair of jets with large values of $E_T$, has an event rate which makes it accessible at the Tevatron. Observation of this process can therefore be used as a luminosity monitor for two- gluon exchange processes, such as the production of a Higgs boson with rapidity gaps on either side.

hep-ph↗

arXiv1999

Hadronic returns to the Z in electron-positron annihilation at high energy

The production of four hadronic jets in e+e- collisions above the Z pole is dominated by the QCD e+e- --> qqqq,qqgg processes and, for sufficiently high energy, the electroweak e+e- --> W+W- --> qqqq process. However there is another mechanism for producing four jets, e+e- --> Z gg --> qqgg, which can be regarded as a `hadronic return' to the Z pole. We investigate this new process in detail

hep-ph↗

arXiv1999

On Particle Multiplicities in Three-jet Events

A thorough verification of the distinct differences in the properties of quark and gluon jets is considered as one of the most instructive tests of the basic ideas of QCD. In the real life experiments such a comparison appears to be quite a delicate task and various subtle issues require further theoretical efforts. In this paper we discuss in detail the possibility to extract the theoretically adequate information from the particle multiplicity patterns in three-jet events in e+e- annihilation.

hep-ph↗

arXiv1999

Screened-Coulomb ansatz for the non-factorizable radiative corrections to the off-shell W^+ W^- production

We demonstrate that the results of the complete first order calculation of the non-factorizable QED corrections to the single-inclusive cross-sections for $e^+e^- \to W^+W^- \to 4$ fermions could be very well reproduced by a simple physically motivated ansatz. The latter allows to take into account effectively the screening role of the non-Coulomb radiative mechanisms by introducing a dampening factor in front of the width-dependent part of the known first-order Coulomb correction, the so-called screened-Coulomb ansatz.

hep-ph↗