119400238
Modelling power corrections to the Bjorken sum rule for the neutrino structure function F1
Direct measurements of the structure functions Fνp1 and Fνn1 at a neutrino factory would allow for an accurate extraction of αs from the Q2-dependence of the Bjorken sum rule, complementing that based on the Gross–Llewellyn-Smith sum rule for F3. We estimate the power (1/Q2-) corrections to the Bjorken sum rule in the instanton vacuum model. For the reduced matrix element of the flavour-nonsinglet twist-4 operator ūgμνγνγ5u − (u → d) we obtain a value of 0.18 GeV2, in good agreement with the QCD sum rule calculations of Braun and Kolesnichenko. Our result allows one to reduce the theoretical error in the determination of αs.
16303633
Rapidity gap survival in central exclusive diffraction: Dynamical mechanisms and uncertainties
We summarize our understanding of the dynamical mechanisms governing rapidity gap survival in central exclusive diffraction, pp -> p + H + p (H = high-mass system), and discuss the uncertainties in present estimates of the survival probability. The main suppression of diffractive scattering is due to inelastic soft spectator interactions at small pp impact parameters and can be described in a mean-field approximation (independent hard and soft interactions). Moderate extra suppression results from fluctuations of the partonic configurations of the colliding protons. At LHC energies absorptive interactions of hard spectator partons associated with the gg -> H process reach the black-disk regime and cause substantial additional suppression, pushing the survival probability below 0.01.
55072904
Transverse nucleon structure and diagnostics of hard parton-parton processes at LHC
We propose a new method to determine at what transverse momenta particle production in high-energy pp collisions is governed by hard parton-parton processes. Using information on the transverse spatial distribution of partons obtained from hard exclusive processes in ep/\gamma p scattering, we evaluate the impact parameter distribution of pp collisions with a hard parton-parton process as a function of p_T of the produced parton (jet). We find that the average pp impact parameters in such events depend very weakly on p_T in the range 2 < p_T < few 100 GeV, while they are much smaller than those in minimum-bias inelastic collisions. The impact parameters in turn govern the observable transverse multiplicity in such events (in the direction perpendicular to the trigger particle or jet). Measuring the transverse multiplicity as a function of p_T thus provides an effective tool for determining the minimum p_T for which a given trigger particle originates from a hard parton-parton process.
125666710
Nucleon matrix elements of twist - three and twist -4 operators from the instanton vacuum
16801030
Polarized antiquark flavor asymmetry in Drell–Yan pair production
Abstract. We investigate the role of the flavor asymmetry of the nucleon's polarized antiquark distributions in Drell–Yan lepton pair production in polarized nucleon–nucleon collisions at HERA (fixed–target) and RHIC energies. It is shown that the large polarized antiquark flavor asymmetry predicted by model calculations in the large–$N_c$ limit (chiral quark–soliton model) has a dramatic effect on the double spin asymmetries in high mass lepton pair production, as well as on the single spin asymmetries in lepton pair production through $W^\pm$–bosons at $M^2 = M_W^2$.
121347456
On nucleon parton distributions from the chiral quark-soliton model
27937897
Creation and detection of a mesoscopic gas in a nonlocal quantum superposition.
We investigate the scattering of a quantum matter wave soliton on a barrier in a one-dimensional geometry, and we show that it can lead to mesoscopic quantum superposition states, where the atomic gas is in a coherent superposition of being in the half-space to the left of the barrier and being in the half-space to the right of the barrier. We propose an interferometric method to reveal the coherent nature of this superposition, and we discuss in detail the experimental feasibility.