Quark structure of hadrons and high energy collisions

There exists a large field for phenomenological models in which the knowledge of the structure of hadrons in terms of QCD constituents obtained from deep inelastic scatterings is related to their behaviour in soft processes. One of the simplest and oldest models is the additive quark model, with the rules of quark statistics following from it. Originally, the relations of quark combinatorics for hadron yields were based on the qualitative description of a multiparticle production process as a process of the production of non-correlated quarks and antiquarks followed by their subsequent fusion into hadrons [20],[21]. As a large amount of new precision measurements appear, and, on the other hand, our understanding of QCD becomes deeper, a new level of understanding of quark-gluon physics in the region of soft interactions forces us to review the relations of quark combinatorics. To do so, an especially good possibility is provided by the experimental data for hadronic Z^0 decays which allow us to check the relations of quark combinatorics for a new type of processes: quark jets in the decays Z^0 -> q\bar{q} -> hadrons [32].Comment: 55 pages, 23 figure

QND and higher order effects for a nonlinear meter in an interferometric gravitational wave antenna

A new optical topology and signal readout strategy for a laser interferometer gravitational wave detector were proposed recently by Braginsky and Khalili . Their method is based on using a nonlinear medium inside a microwave oscillator to detect the gravitational-wave-induced spatial shift of the interferometer's standing optical wave. This paper proposes a quantum nondemolition (QND) scheme that could be realistically used for such a readout device and discusses a "fundamental" sensitivity limit imposed by a higher order optical effect.Comment: LaTex, 17 pages, 3 figure

Charge renormalization and phase separation in colloidal suspensions

We explore the effects of counterion condensation on fluid-fluid phase separation in charged colloidal suspensions. It is found that formation of double layers around the colloidal particles stabilizes suspensions against phase separation. Addition of salt, however, produces an instability which, in principle, can lead to a fluid-fluid separation. The instability, however, is so weak that it should be impossible to observe a fully equilibrated coexistence experimentally.Comment: 7 pages, Europhysics Letters (in press

How to reduce the suspension thermal noise in LIGO without improving the Q's of the pendulum and violin modes

The suspension noise in interferometric gravitational wave detectors is caused by losses at the top and the bottom attachments of each suspension fiber. We use the Fluctuation-Dissipation theorem to argue that by careful positioning of the laser beam spot on the mirror face it is possible to reduce the contribution of the bottom attachment point to the suspension noise by several orders of magnitude. For example, for the initial and enhanced LIGO design parameters (i.e. mirror masses and sizes, and suspension fibers' lengths and diameters) we predict a reduction of $\sim 100$ in the "bottom" spectral density throughout the band $35-100\hbox{Hz}$ of serious thermal noise. We then propose a readout scheme which suppresses the suspension noise contribution of the top attachment point. The idea is to monitor an averaged horizontal displacement of the fiber of length $l$; this allows one to record the contribution of the top attachment point to the suspension noise, and later subtract it it from the interferometer readout. For enhanced LIGO this would allow a suppression factor about 100 in spectral density of suspension thermal noise.Comment: a few misprints corrected; submitted to Classical and Quantum Gravit

Next-to-leading-order corrections to exclusive processes in kTk_T factorization

We calculate next-to-leading-order (NLO) corrections to exclusive processes in $k_T$ factorization theorem, taking $\pi\gamma^*\to\gamma$ as an example. Partons off-shell by $k_T^2$ are considered in both the quark diagrams from full QCD and the effective diagrams for the pion wave function. The gauge dependences in the above two sets of diagrams cancel, when deriving the $k_T$-dependent hard kernel as their difference. The gauge invariance of the hard kernel is then proven to all orders by induction. The light-cone singularities in the $k_T$-dependent pion wave function are regularized by rotating the Wilson lines away from the light cone. This regularization introduces a factorization-scheme dependence into the hard kernel, which can be minimized in the standard way. Both the large double logarithms $\ln^2k_T$ and $\ln^2 x$, $x$ being a parton momentum fraction, arise from the loop correction to the virtual photon vertex, the former being absorbed into the pion wave function and organized by the $k_T$ resummation, and the latter absorbed into a jet function and organized by the threshold resummation. The NLO corrections are found to be only few-percent for $\pi\gamma^*\to\gamma$, if setting the factorization scale to the momentum transfer from the virtual photon.Comment: 13 pages; version to appear in Physical Review

Inclusive production in a QCD and N=4 SYM motivated model for soft interactions

The results presented in this paper differ from our previous unsuccessful attempt to predict the rapidity distribution at $W = 7 \,TeV$. The original version of our model (GLMM) only summed a particular class of Pomeron diagrams (enhanced diagrams). We believe that this was the reason for our failure to describe the $7 \,TeV$ inclusive LHC data. We have developed a new approach (GLM) that also includes the summation of the semi-enhanced diagrams.This contribution is essential for a successful description of the inclusive distributions, which is presented here.Comment: 4 pages, 3 figure

Speed Meter As a Quantum Nondemolition Measuring Device for Force

Quantum noise is an important issue for advanced LIGO. Although it is in principle possible to beat the Standard Quantum Limit (SQL), no practical recipe has been found yet. This paper dicusses quantum noise in the context of speedmeter-a devise monitoring the speed of the testmass. The scheme proposed to overcome SQL in this case might be more practical than the methods based on monitoring position of the testmass.Comment: 7 pages of RevTex, 1 postscript figur

Monopole solutions to the Bogomolny equation as three-dimensional generalizations of the Kronecker series

The Dirac monopole on a three-dimensional torus is considered as a solution to the Bogomolny equation with non-trivial boundary conditions. The analytical continuation of the obtained solution is shown to be a three-dimensional generalization of the Kronecker series. It satisfies the corresponding functional equation and is invariant under modular transformations.Comment: 13 pages, 1 figur

Stochastic stabilization of cosmological photons

The stability of photon trajectories in models of the Universe that have constant spatial curvature is determined by the sign of the curvature: they are exponentially unstable if the curvature is negative and stable if it is positive or zero. We demonstrate that random fluctuations in the curvature provide an additional stabilizing mechanism. This mechanism is analogous to the one responsible for stabilizing the stochastic Kapitsa pendulum. When the mean curvature is negative it is capable of stabilizing the photon trajectories; when the mean curvature is zero or positive it determines the characteristic frequency with which neighbouring trajectories oscillate about each other. In constant negative curvature models of the Universe that have compact topology, exponential instability implies chaos (e.g. mixing) in the photon dynamics. We discuss some consequences of stochastic stabilization in this context.Comment: 4 pages, 3 postscript figures in color which are also appropriate for black and white printers; v2 emphasizes relevance to flat as well as negatively curved cosmologies; to appear in J. Phys.

Equation of state of charged colloidal suspensions and its dependence on the thermodynamic route

The thermodynamic properties of highly charged colloidal suspensions in contact with a salt reservoir are investigated in the framework of the Renormalized Jellium Model (RJM). It is found that the equation of state is very sensitive to the particular thermodynamic route used to obtain it. Specifically, the osmotic pressure calculated within the RJM using the contact value theorem can be very different from the pressure calculated using the Kirkwood-Buff fluctuation relations. On the other hand, Monte Carlo (MC) simulations show that both the effective pair potentials and the correlation functions are accurately predicted by the RJM. It is suggested that the lack of self-consistency in the thermodynamics of the RJM is a result of neglected electrostatic correlations between the counterions and coions