7,951 research outputs found
Elliptic Schlesinger system and Painlev{\'e} VI
We construct an elliptic generalization of the Schlesinger system (ESS) with
positions of marked points on an elliptic curve and its modular parameter as
independent variables (the parameters in the moduli space of the complex
structure). ESS is a non-autonomous Hamiltonian system with pair-wise commuting
Hamiltonians. The system is bihamiltonian with respect to the linear and the
quadratic Poisson brackets. The latter are the multi-color generalization of
the Sklyanin-Feigin-Odeskii classical algebras. We give the Lax form of the
ESS. The Lax matrix defines a connection of a flat bundle of degree one over
the elliptic curve with first order poles at the marked points.
The ESS is the monodromy independence condition on the complex structure for
the linear systems related to the flat bundle.
The case of four points for a special initial data is reduced to the
Painlev{\'e} VI equation in the form of the Zhukovsky-Volterra gyrostat,
proposed in our previous paper.Comment: 16 pages; Dedicated to the centenary of the publication of the
Painleve VI equation in the Comptes Rendus de l'Academie des Sciences de
Paris by Richard Fuchs in 190
Why is the condensed phase of DNA preferred at higher temperature? DNA compaction in the presence of a multivalent cation
Upon the addition of multivalent cations, a giant DNA chain exhibits a large
discrete transition from an elongated coil into a folded compact state. We
performed single-chain observation of long DNAs in the presence of a
tetravalent cation (spermine), at various temperatures and monovalent salt
concentrations. We confirmed that the compact state is preferred at higher
temperatures and at lower monovalent salt concentrations. This result is
interpreted in terms of an increase in the net translational entropy of small
ions due to ionic exchange between higher and lower valence ions.Comment: 4pages,3figure
Nonlinear QCD Evolution: Saturation without Unitarization
We consider the perturbative description of saturation based on the nonlinear
QCD evolution equation of Balitsky and Kovchegov (BK). Although the nonlinear
corrections lead to saturation of the scattering amplitude locally in impact
parameter space, we show that they do not unitarize the total cross section.
The total cross section for the scattering of a strongly interacting probe on a
hadronic target is found to grow exponentially with rapidity. The origin of
this violation of unitarity is the presence of long range Coulomb fields away
from the saturation region. The growth of these fields with rapidity is not
tempered by the nonlinearity of the BK equation.Comment: 4 pages, RevTe
Has HERA reached a new QCD regime?
These notes are a summary of our efforts to answer the question in the title.
Our answer is in the affirmative as: (i) HERA data indicate a large value of
the gluon structure function; (ii) no contradictions with the asymptotic
predictions of high density QCD have been observed; and (iii) the numerical
estimates of our model give a natural description of the size of deviation from
the routine DGLAP explanation. We discuss the alternative approaches and
possible new experiments.Comment: 29 pages, 37 figures in eps file
Angular pattern of minijet transverse energy flow in hadron and nuclear collisions
The azimuthal asymmetry of minijet system produced at the early stage of
nucleon-nucleon and nuclear collisions in a central rapidity window is studied.
We show that in pp collisions the minijet transverse energy production in a
central rapidity window is essentially unbalanced in azimuth due to asymmetric
contributions in which only one minijet hits the acceptance window. We further
study the angular pattern of transverse energy flow generated by semihard
degrees of freedom at the early stage of high energy nuclear collisions and its
dependence on the number of semihard collisions in the models both including
and neglecting soft contributions to the inelastic cross section at RHIC and
LHC energies as well as on the choice of the infrared cutoff.Comment: 25 LaTeX pages, 11 figures embedded with epsf; expanded versio
Three charged particles in the continuum. Astrophysical examples
We suggest a new adiabatic approach for description of three charged
particles in the continuum. This approach is based on the Coulomb-Fourier
transformation (CFT) of three body Hamiltonian, which allows to develop a
scheme, alternative to Born-Oppenheimer one.
The approach appears as an expansion of the kernels of corresponding integral
transformations in terms of small mass-ratio parameter. To be specific, the
results are presented for the system in the continuum. The wave function
of a such system is compared with that one which is used for estimation of the
rate for triple reaction which take place as a step of
-cycle in the center of the Sun. The problem of microscopic screening for
this particular reaction is discussed
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
Benchmarks for the Forward Observables at RHIC, the Tevatron-run II and the LHC
We present predictions on the total cross sections and on the ratio of the
real part to the imaginary part of the elastic amplitude (rho parameter) for
present and future pp and pbar p colliders, and on total cross sections for
gamma p -> hadrons at cosmic-ray energies and for gamma gamma-> hadrons up to
sqrt{s}=1 TeV. These predictions are based on an extensive study of possible
analytic parametrisations invoking the biggest hadronic dataset available at
t=0. The uncertainties on total cross sections, including the systematic errors
due to contradictory data points from FNAL, can reach 1.9% at RHIC, 3.1% at the
Tevatron, and 4.8% at the LHC, whereas those on the rho parameter are
respectively 5.4%, 5.2%, and 5.4%.Comment: 11 pages, 2 figures, 4 tables, RevTeX
Enhanced tidal disruption rates from massive black hole binaries
"Hard" massive black hole (MBH) binaries embedded in steep stellar cusps can
shrink via three-body slingshot interactions. We show that this process will
inevitably be accompanied by a burst of stellar tidal disruptions, at a rate
that can be several orders of magnitude larger than that appropriate for a
single MBH. Our numerical scattering experiments reveal that: 1) a significant
fraction of stars initially bound to the primary hole are scattered into its
tidal disruption loss cone by gravitational interactions with the secondary
hole, an enhancement effect that is more pronounced for very unequal-mass
binaries; 2) about 25% (40%) of all strongly interacting stars are tidally
disrupted by a MBH binary of mass ratio q=1/81 (q=1/243) and eccentricity 0.1;
and 3) two mechanisms dominate the fueling of the tidal disruption loss cone, a
Kozai non-resonant interaction that causes the secular evolution of the stellar
angular momentum in the field of the binary, and the effect of close encounters
with the secondary hole that change the stellar orbital parameters in a chaotic
way. For a hard MBH binary of 10^7 solar masses and mass ratio 0.01, embedded
in an isothermal stellar cusp of velocity dispersion sigma*=100 km/s, the tidal
disruption rate can be as large as 1/yr. This is 4 orders of magnitude higher
than estimated for a single MBH fed by two-body relaxation. When applied to the
case of a putative intermediate-mass black hole inspiraling onto Sgr A*, our
results predict tidal disruption rates ~0.05-0.1/yr.Comment: 5 pages, 3 figures, accepted for publication in the Astrophysical
Journal Letter
- …