56668894
First results on $A_1^p$ and $g_1^p$ at low x and low $Q^2$ from COMPASS
8883252
Observation of a New Narrow Axial-Vector Meson a1(1420).
The COMPASS Collaboration at CERN has measured diffractive dissociation of 190  GeV/c pions into the π(-)π(-)π(+) final state using a stationary hydrogen target. A partial-wave analysis (PWA) was performed in bins of 3π mass and four-momentum transfer using the isobar model and the so far largest PWA model consisting of 88 waves. A narrow peak is observed in the f0(980)π channel with spin, parity and C-parity quantum numbers J(PC)=1(++). We present a resonance-model study of a subset of the spin-density matrix selecting 3π states with J(PC)=2(++) and 4(++) decaying into ρ(770)π and with J(PC)=1(++) decaying into f0(980)π. We identify a new a1 meson with mass (1414(-13)(+15))  MeV/c2 and width (153(-23)(+8))  MeV/c2. Within the final states investigated in our analysis, we observe the new a1(1420) decaying only into f0(980)π, suggesting its exotic nature.
55417521
Evolution of semilocal string networks: large-scale properties
We report on a detailed numerical study of the evolution of semilocal string networks, based on the largest and most accurate field theory simulations of these objects to date. We focus on the large-scale network properties, confirming earlier indications (coming from smaller simulations) that linear scaling is the attractor solution for the entire parameter space of initial conditions that we are able to probe. We also provide a brief comparison of our numerical results with the predictions of a previously developed one-scale model for the overall evolution of these networks. Two subsequent papers will discuss in more detail the analytic modeling of the semilocal segment populations as well as optimized numerical diagnostics.
117951510
Parametric resonance with multi‐frequencies in preheating
We present here an extended abstract of the results derived in [1], We study the decay of the inflaton field to another scalar field χ in the parametric resonance preheating mechanism. We consider the presence of several simultaneous couplings between the fields. We show that the contribution for the χ field energy density of the higher harmonic is a small fraction of that of the fundamental frequency, and so the presence of a finite number of higher harmonics has limited cosmological implications
115300255
On the theory of the invisible arion
Models with an ''invisible'' arion, a massless Goldstone particle interacting weakly with quarks and leptons, are considered. The coupling constant with photons, which is needed for the occurrence of arion--photon oscillations in an external magnetic field, is estimated.
119519761
SCALAR FIELD PHASE DYNAMICS IN PREHEATING
We study the model of a massive inflaton field $\phi$ coupled to another scalar filed $\chi$ with interaction term $g^2\phi^2\chi^2$ for the first stage of preheating. We obtain the the behavior of the phase in terms of the iteration of a simple family of circle maps. When expansion of the universe is taken into account the qualitative behavior of the phase and growth number evolution is reminiscent of the behavior found in the case without expansion.
121568899
Dispersion relations for polarization operator of a photon in an external non-Abelian field
The thresholds for photoproduction of scalar quarks in an external non-Abelian field are determined. A dispersion relation is obtained for the trace of the photon polarization operator with internal quark loop in this field. The explicit form of the trace is calculated by means of this relation.