arXiv subjects
Publications and source records attributed to A. V. Kisselev.
The average charged hadron multiplicity in the $e^+e^-$ events with the primary $t\bar{t}$-pair at the collision energy 500 GeV, as well as the average multiplicity of charged hadrons from the top quark are calculated in QCD to be $86.7 \pm 1.11$ and $41.0 \pm 0.54$, respectively.
The Randall-Sundrum (RS) model with the small curvature is studied. In such a scheme the mass spectrum of Kaluza-Klein (KK) gravitons is similar to that in a model with one extra flat dimension. The gravity effects in the Bhabha scattering at the energy 1 TeV are estimated. The calculations are based on the analytical formula which describes virtual graviton contributions. It takes into account both a discrete character of the mass spectrum and nonzero widths of the KK gravitons.
The Randall-Sundrum (RS) model with a small curvature is considered. The mass spectrum of Kaluza-Klein (KK) gravitons in such a scheme is similar (although not equivalent) to that in a model with one extra dimension in a flat metric. The gravity effects in the processes $e^+e^- \to e^+e^-$ and $e^+e^- \toμ^+μ^-$ at the collision energy 1 TeV are presented. Our calculations are based on the previously obtained formula for virtual graviton contributions which takes into account both a discrete character of the mass spectrum and nonzero widths of the KK gravitons.
The multiple hadron production in the events induced by the heavy primary quarks in $e^+e^-$ annihilation is reconsidered with account of corrected experimental data. New value for the multiplicity in $b\bar{b}$ events is presented on the basis of pQCD estimates.
This paper has been withdrawn by the authors because the authors excluded the paper from electronic proceedings of the conference.
The small curvature option of the Randall-Sundrum model with two branes is considered which has almost continuous spectrum of low-mass Kaluza-Klein gravitons. It is shown that gravity effects related with these excitations can be detected in double diffractive events at the LHC and in inclined air showers induced by interactions of cosmic neutrinos with atmospheric nucleons at ultra-high energies.
The experimentally measurable effects related to extra dimensional gravity in a RS-type brane world are estimated. Two options of the RS framework (namely, with small and large curvature) are considered. It is shown that both can be detected by the joint experiment of the CMS and TOTEM Collaborations at the LHC.
The contribution of virtual s-channel Kaluza-Klein (KK) gravitons to high energy scattering of the SM fields in the Randall-Sundrum (RS) model with two branes is studied. The small curvature option of the RS model is considered in which the KK gravitons are narrow low-mass spin-2 resonances. The analytical tree-level expression for a process-independent gravity part of the scattering amplitude is derived, accounting for nonzero graviton widths. It is shown that one cannot get a correct result, if a series of graviton resonances is replaced by a continuous mass distribution, in spite of the small graviton mass splitting. Such a replacement appeared to be justified only in the trans-Planckian energy region.
The inelastic scattering of the brane fields induced by $t$-channel gravireggeons exchanges in the RS model with a small curvature $κ$ is considered, and the imaginary part of the eikonal is analytically calculated. It is demonstrated that the results can be obtained from the corresponding formulae previously derived in the ADD model with one extra dimension of the size $R_c$ by formal replacement $R_c \to (πκ)^{-1}$. The inelastic cross section for the scattering of ultra-high neutrino off the nucleon is numerically estimated for the case $κ\ll \bar{M}_5 \sim 1$ TeV, where $\bar{M}_5$ is a reduced Planck scale in five warped dimensions.
On the basis of some peculiar scaling properties of the OPE coefficient functions, we give the lower bounds for F_2^{c\bar{c}} and F_2^{b\bar{b}} independently of the properties of the gluon density function. Predictions for F_2^{b\bar{b}} within reach of HERA are made.
A new method for calculating the coefficient functions of the operator product expansion is proposed which does not depend explicitly on elementary fields. Coefficient functions are defined entirely in terms of composite operators. The method is illustrated in the case of QCD nonsinglet operators.
We consider the scattering of the brane fields due to t-channel massive graviton exchanges in the Randall-Sundrum model. The eikonal amplitude is analytically calculated and both differential and total neutrino-nucleon cross sections are estimated. The event rate of quasi-horizontal air showers induced by cosmic neutrinos, which can be detected at the Pierre Auger Observatory, is presented for two different fluxes of cosmogenic neutrinos.
The gravity effects in high-energy scattering, described by a four-dimensional eikonal amplitude related to gravireggeons induced by compact extra dimensions are studied. It is demonstrated that the real part of the eikonal (with a massless mode subtracted) dominates its imaginary part at both small and large impact parameters, in contrast to the usual case of hadronic high-energy behavior. The real part of the scattering amplitude exhibits an exponential falloff at large momentum transfer, similar to that of the imaginary part of the amplitude.
We present the results on non-perturbative quantum gravity effects related to extra dimensions which can be comparable, in some cases, with the SM contributions, e.g. in lepton-lepton or lepton-nucleon scattering. The case of cosmic neutrino gravitational interaction with atmospheric nucleons is considered in detail.
The multidimensional space-time with $(D-4)$ compact extra space dimensions and SM fields confined on four-dimensional brane is considered. The elastic scattering amplitude of two particles interacting by gravitational forces is calculated at superplanckian energies. A particular attention is paid to a proper account of zero (massless) graviton mode. The renormalized Born pole is reproduced in the eikonal amplitude which makes a leading contribution at small momentum transfers. This singular part of the amplitude coincides with well-known $D$-dimensional amplitude taken at $D \to 4$. The expression for a contribution from massive graviton modes to the eikonal is derived, and it asymptotics in the impact parameter are calculated. Our formula gives correct four-dimensional result at $R_c \to 0$, where $R_c$ is the radius of the higher dimensions, contrary to formulae obtained in recent papers on collisions of particles living on the brane. The results are also compared with those obtained previously for the scattering of the bulk fields in flat higher dimensions.
Different possibilities of a detection of signals from extra space dimensions at high energy colliders are reviewed.
Quark mass effects are analyzed at high $Q^2$ in the current fragmentation region of DIS. It is found that the linear combination $F_2-2.75F^c_2$ scales at large $Q^2$ and small $x$. We obtained a lower bound for the ratio $F^c_2/F_2$ which lies very close to the data from HERA.
The multiplicity of charged hadrons in the current fragmentation region of both the c.m.s. and the Breit frame of deep inelastic scattering is calculated and compared with the HERA data. The results are in agreeement with Yang's hypothesis that the efficiency of high energy processes increases at larger momentum transfer.