Production properties of A1 in πp interactions at 5.45 GeV/c

The production of the peripheral 3π mass enhancement in the A₁ region is described. The differential cross section and its variation with 3π mass is studied and the spin density matrix elements are given for the t-channel and s-channel helicity frames. As observed in π⁻p interactions t channel but not s channel helicity is conserved. A Deck type double Regge trajectory exchange amplitude gives good fits to the experimental distributions. Its use is supported by the equality of ?_{0 0} for the A₁ and ?00 for the ? in the t-channel, as noted by Donohue.     

Lower bounds on the slope parameter

A rigorous lower bound on the slope parameter γ(s, t) = d ln A(s, t)/dt is derived for 0 < t < t₀ where A(s, t) is the absorptive part of the elastic scattering amplitude and t₀ is related to the right extreme of the Lehmann-Martin ellipse. When A(s, t) has high-energy behavior like s^α(t)ln^η(t)s…, this lower bound on α(s, t) is used to obtain lower bounds on α′(t) for 0 < t < t₀, which saturate for ‘parabolic trajectories’. We also obtain a lower bound on γ(s, t) for t < 0 which can be used to find the nearforward region in which γ(s, t) cannot vanish.     

On the behavior of the πN partial wave amplitudes ats=0

The behavior of theπN partial wave amplitudes in the limitss→+0 ands→? 0 is related to backward scattering in thes- andt-channel, respectively. Assuming Mandelstam analyticity we prove with the aid of the Phragmen-Lindelöf theorem that the amplitudes for high energy backward scattering inπN→πN andππ→N¯N are equal and therefore dominated by the same exchange mechanism, namely Reggeized Fermion exchange. The dominating Regge trajectory is the Δ_δ-trajectory, and it is shown that theπN partial wave amplitudes diverge fors→±0 as \(s^{ - \alpha \Delta _\delta (0) - {1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-0em} 2}} \) . — Reduced amplitudes are defined which are regular ats=0. — Using recent results ofπN backward scattering real and imaginary part of thes-wave amplitudef ₀₊ ^(?) are calculated in the interval 0≦s≦7.     

L ∞ estimates for the space-homogeneous Boltzmann equation

This paper studies the boundedness of solutionsf of the initial-value problem for the space-homogeneous Boltzmann equation for inverse kth power forces, whenk>5, and under angular cutoff. The main result is that if the initial value isf ₀ ? 0 with (1 + ¦υ¦²)φ₀ εL ¹ and (1 + ¦υ¦)^s f ₀ε L^∞ for somes > 2, then (1 + ¦υ¦^s'f _tεL ^∞ fort>0 and ess_υ,t sup(1 + ¦υ¦)^s'f(υ, t,) < ∞ for anys′ ? s whens ? 5, and anys′ ? s ifs > 5.     

Construction of tensor exchange amplitudes in KN and KN CEX reactions

K⁺n charge exchange (CEX) polarization data obtained recently by the Saclay group at CERN are supplemented by differential cross-section data and by information on K^?p CEX, and used to construct tensor exchange non-flip and flip components T₀ and T₁ of the s-channel helicity amplitudes directly from data at 6 GeV/c and for |t| ? 0.9. Vector exchange amplitudes are assumed to be known from πN scattering. The sensitivity of solutions to the uncertainties in the input data is examined in great detail. In general we find a unique solution for all t.We observe new features in the t-structure of non-flip and flip amplitudes. Re T₀Re T₀ have simple zeros at t ≈ ?0.45 and t ≈ ?0.65. Im T₀ has a dip or a double zero at t ≈ ?0.16 and a double zero structure at t ≈ ?0.45. Im T₁ has two simple zeros at t ≈ ?0.45 and t ≈ ?0.70. Violations of weak EXD in both amplitudes correspond to a lower A₂ trajectory by approximately Δα ≈ 0.1. If certain conditions are satisfied by the input data, a discrete ambiguity exists in the solutions for |t| ? 0.55 and this possibility is also carefully examined.     

s-and t-channel helicity conservation of pion induced nucleon diffraction dissociation at 3.9 GeV/c and the implications of a two-component model

A study of schannel and t-channel helicity conservation has been carried out on a prism plot separated sample of 3.9 GeV/cπ^±p → π (Nπ)_dd diffraction dissociation events. s-channel helicity conservation is found to be strongly violated while t-channel helicity conservation is found to be mildly violated. These results are similar to that found at 11.7 GeV/c. We explain these violations on the basis of a “two-component model” of which the first component is a single exchange amplitude. We postulate that this amplitude is the generalization of the pomeron exchange amplitude which may conserve s-channel helicity. The second component of the model is a double exchange mechanism which strongly violates s-channel helicity. The predictions of this model agree with the experimental data.     

A comparative study of ϱ0 photoproduced on d,n and p at 7.5 GeV

A 7.5 GeV linearly polarized photon beam was used to study ?⁰ production on d, n and p in the SLAC 82 inch bubble chamber. The production of ?⁰ is found to proceed mainly viat-channel natural parity exchange and to conserve s-channel c.m.s. helicity for small t. The I = 1 contribution to the γN → ?⁰t-channel amplitude is found to be small at 7.5 GeV.     

A study of the charge-exchange reaction pp → nΔ++(1232) at ISR energies

We report on a study of the charge-exchange reaction pp → nΔ⁺⁺(1232) at the CERN intersecting storage rings (ISR) in the energy range √s = 23 to 53 GeV. From our analysis of the energy dependence of the total cross-section, of the differential cross-section dσ/dt and of the decay angular distributions we find evidence that pion exchange is dominant up to √s = 23 GeV and that (?+A₂) exchange dominates the reaction for √s ? 30 GeV, as described by simple Regge-pole models.     

Factorization and the couplings of the vacuum trajectory

The decoupling theorems associated with an isolated factorizable pomeron pole of unit intercept are re-examined. It is found that the coupling of three such poles, Γ(t, t, 0), need not vanish, precisely at the point t = 0. This is demonstrated by summing only over states in the appropriate unitarity sum, and sum rule, which are consistent with the M², s/M² → ∞ limit. The triple-Regge region then makes a constant contribution to σ_total, insteadsb of the ln lns result obtained if the isolated pole is assumed to couple also to states such that s/M² = constant. The physical implications regarding factorization and the pole-cut relationship are discussed. The relationship between higher order optical theorems (Mueller discontinuities) and particular terms in the unitarity sum for the two → two absorptive part A₂₂ is exploited. Consistent contributions to the triple-Regge region contribute constant vertex corrections to pure pole behaviour in A₂₂. There is no cut contribution and the magnitude of the vertex corrections reflects the relative amount of diffractive production. The analysis is extended to multiple fireball production where pure multipole structures emerge. The series naturally terminates if the diffractive component is sufficiently small. The implications for the behaviour of the total cross section at machine energies are discussed.     

On Asymptotics for the Airy Process

The Airy process t→A(t), introduced by Prähofer and Spohn, is the limiting stationary process for a polynuclear growth model. Adler and van Moerbeke found a PDE in the variables s ₁,s ₂, and t for the probability Pr(A(0)≤s ₁, A(t)≤s ₂). Using this they were able, assuming the truth of a certain conjecture and appropriate uniformity, to obtain the first few terms of an asymptotic expansion for this probability as t→∞, with fixed s ₁ and s ₂. We shall show that the expansion can be obtained by using the Fredholm determinant representation for the probability. The main ingredients are formulas obtained by the author and C. A. Tracy in the derivation of the Painlevé II representation for the distribution function F ₂ plus a few others obtained in the same way.     

Two-body propagators with dynamic effective interactions in a many-fermion medium: I. General structure

Excitations of the many-body medium cause dynamic effective interactions between fermions. In actual calculations these interactions are almost always replaced by static approximations. In this paper a Green function approach is outlined which preserves the dynamic structure of the interactions. The central quantity is the four-vertex or two-fermion scattering amplitude Γ in the medium, which depends on three energy variables s, t, and u. Integral equations connect Γ to irreducible effective interactions in the three channels. With static interactions the s- and t-channels correspond to particle-particle and particle-hole configurations, respectively. Dynamic interactions mix these configurations. They also introduce poles in the crossed channels: the exchange of a phonon is a t-pole in the s-channel while pairons induce s-poles in the t-channel. Poles of the one-body propagator G(ω) and the two-body propagators K(s) and K(t) correspond to states of the A ± 1, A ± 2 and A-particle systems. The dynamic coupling between channels results in an intricate connection between various aspects of the many-fermion problem.     

Supersymmetry and the division algebras

We show how spinors in space-times of dimension D = t + s, where t is the time dimension, are associated for s - t = 1, 2, 4, 8 (and if t = 0, 1, 2) with the number systems (division algebras), $\text{|R, C, H, O}$. For t = 1 and s - t = 1, 2, 4 this association is “realized” by the sequence of Lorentz groups S1(2,$\text{|R}$), S1(2;$\text{|C}$), S1(2;$\text{|H}$) for D = 3, 4, 6 respectively. We discuss how octonions may be related to D = 10. For D = 6 we give details of S1(2; $\text{|H}$) spinors and construct supersymmetric models with them. These results explain various “empirical” observations in the literature relating quaternions and supersymmetry.     

Rigorous lower and upper bounds for the slope parameter

It is proved within the framework of axiomatic field theory that the logarithmic derivative of the absorptive part of the scattering amplitude with respect to momentum transfer is bounded from above by $\text{(15}\text{log}\text{s)}\text{[4√t(2 ? √t)]}$ for a sequence of s→+∞, and from below either in the s-channel by const. × s^?5 log^?4s or in the u-channel by const. × u^?5 log^?4u for at least one sequence of s or u →+∞, respectively. In the particular case of the s?u even-symmetric amplitude, a stronger lower bound is obtained; namely, const. × s^?5 log^?4s for at least one sequence of s→+∞. Here s, t, and u are the usual Mandelstam variables, and all bounds are obtained in the forward and the unphysical regions: 0?t<4 (in units of pion mass).It is observed that the Regge amplitude β(t)s^α(t) of high-energy scattering gives the same energy dependence as the above upper bound, and, furthermore, that the slope of the Regge trajectory is bounded from above by $\text{15}\text{[4√t(2 ? √t)]}\text{for}\text{0 < t < 4}$.     

Entanglement dynamics in Coriolis coupled rovibrational states of formaldehyde

The entanglement dynamics of two vibrational modes of a polyatomic molecule coupled by Coriolis interaction to overall molecular rotation is studied in terms of two negativities, N(t) and N_s(t), respectively, defined by the minimum of the eigenvalues and by the sum of the negative eigenvalues of the partial transpose of a density matrix. Various initial states are the products of Dicke states and the products of coherent states of vibrations and rotations. Formaldehyde is taken as an example, and the von Neumann entropy s(t) is simulated for the comparison with both negativities. It is shown that negativity N_s(t) is positively correlated with entropy s(t), and the correlated behavior between negativity N(t) and entropy s(t) strongly depends on initial states. However, these three indicators of entanglement display a dominantly positive correlation for the coherent states with small or large parameters. In addition, for the latter state two quantities N(t) and s(t) are nearly unchanged for a long time. This time can be further increased by the increasing of vibrational quantum number so that molecular information processing and quantum computing is allowed. These results are useful in quantum information theory.     

Quark loops and spin-flip effects in pomeron exchange

On the basis of QCD at large distances with taking account of some nonperturbative properties of the theory, the possibility of spin-flip effects in high energy hadron processes at fixed momenta transfer is investigated. It is shown that the diagrams with the quark loops in QCD at large distances may lead to the spin-flip amplitude growing ass fors→∞,t-fixed. The confirmation of this result is obtained by calculations of the nonleading contributions from quark loops int-channel exchange in QED up to the end. Physical mechaisms leading to that behavour of the spin-flip amplitude is discussed. So we conclude that the pomeron has a complicated spin structure.     

Theory of the froissaron exchange

The results of the multi-pomeron exchange theory considered earlier, are shown to depend crucially on the threshold behaviour of the pomeron contribution at t = 4μ_π², under the condition α(0) ? 1 = Δ > α′(0) 4μ_π². The t-channel partial wave f(t) of the multi-pomeron exchange is calculated. In the limit ξ · Δ > 1, where ξ = ln s/4μ², it corresponds to the scattering on a black disk of expanding radius b₀ ≈ a · ξ where a = s/2μ_π ? α′2μ_π. Due to the threshold singularity influence, it does not violate the t-channel unitarity condition. At a sufficiently small value of the froissaron coupling constant g₀₀ ～ Δ³/a², the theory is shown to be simultaneously s-unitary.     

On the zero points of the mandelstam denominators in the complexs-plane: The general two-body process

The relativistic two-body into two-body processes are considered. The areas are described where the denominators of the Mandelstam representation vanish in the complexs-plane if the momentum transfer squaredt and the scattering angle? in the direct channel have physical values. The equations of the lines are given along which either cos?=const andt varies ort=const and cos? varies. The cuts along later lines are suggested if the continua in the crossed channels are replaced by particles. In the general mass case, it is shown that the location of the branch points in the integrand of the partial wave amplitude in the complexs-plane depends on the integration involved. However, any elastic process represents a degeneration when the mentioned dependence does not appear.     

Computable upper bounds for the adiabatic approximation errors

For a given Hermitian Hamiltonian H(s)(s∈[0,1])with eigenvalues Ek(s)and the corresponding eigenstates|Ek(s)(1 k N),adiabatic evolution described by the dilated Hamiltonian HT(t):=H(t/T)(t∈[0,T])starting from any fixed eigenstate|En(0)is discussed in this paper.Under the gap-condition that|Ek(s)-En(s)|λ0 for all s∈[0,1]and all k n,computable upper bounds for the adiabatic approximation errors between the exact solution|ψT(t)and the adiabatic approximation solution|ψadi T(t)to the Schr¨odinger equation i|˙ψT(t)=HT(t)|ψT(t)with the initial condition|ψT(0)=|En(0)are given in terms of fidelity and distance,respectively.As an application,it is proved that when the total evolving time T goes to infinity,|ψT(t)-|ψadi T(t)converges uniformly to zero,which implies that|ψT(t)≈|ψadi T(t)for all t∈[0,T]provided that T is large enough.     

Measurement of π−p → π0n at large momentum transfer

New results on a high statistics measurement of pion-nucleon charge exchange scattering at 40 GeV/c, extending in momentum transfer up to ?t = 1.8 (GeV/c)², are reported and compared with an optical impact parameter model, together with previous data for the reaction π^?p → ηn at the same energy. The imaginary part of the pole trajectory b₀(s) is determined from the slope of the tangent to the maxima of $\text{(?t)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{d}\text{σ}\text{d}\text{t}$. The linear increase of Im b₀(s) with log s, which has been observed at low energies, continues up to 40 GeV/c.