Oscillons in dilaton-scalar theories

It is shown by both analytical methods and numerical simulations that extremely long living spherically symmetric oscillons appear in virtually any real scalar field theory coupled to a massless dilaton (DS theories). In fact such "dilatonic" oscillons are already present in the simplest non-trivial DS theory -- a free massive scalar field coupled to the dilaton. It is shown that in analogy to the previously considered cases with a single nonlinear scalar field, in DS theories there are also time periodic quasibreathers (QB) associated to small amplitude oscillons. Exploiting the QB picture the radiation law of the small amplitude dilatonic oscillons is determined analytically.Comment: extended discussion on stability, to appear in JHEP, 29 pages, 7 figure

Progress on Neutron-Target Multipoles above 1 GeV

We report a new extraction of nucleon resonance couplings using pi- photoproduction cross sections on the neutron. The world database for the process gn-->pi-p above 1 GeV has quadrupled with the addition of new differential cross sections from the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab in Hall B. Differential cross sections from CLAS have been improved with a new final-state interaction determination using a diagrammatic technique taking into account the SAID phenomenological NN and piN final-state interaction amplitudes. Resonance couplings have been extracted and compared to previous determinations. With the addition of these new cross sections, significant changes are seen in the high-energy behavior of the SAID cross sections and amplitudes.Comment: 4 pages, 3 figures, 1 table; talk given at 12th International Workshop on Meson Production, Properties and Interaction (MESON2012), 31 May - 5 June 2012, Krakow, Poland; will be published online in European Journal Web of Conference

Ratios of Elastic Scattering of Pions from 3H and 3He

We have measured the elastic-scattering ratios of normalized yields for charged pions from 3H and 3He in the backward hemisphere. At 180 MeV, we completed the angular distribution begun with our earlier measurements, adding six data points in the angular range of 119 deg to 169 deg in the pi-nucleus center of mass. We also measured an excitation function with data points at 142, 180, 220, and 256 MeV incident pion energy at the largest achievable angle for each energy between 160 deg and 170 deg in the pi-nucleus center of mass. This excitation function corresponds to the energies of our forward-hemisphere studies. The data, taken as a whole, show an apparent role reversal of the two charge-symmetric ratios r1 and r2 in the backward hemisphere. Also, for data > 100 deg we observe a strong dependence on the four-momentum transfer squared (-t) for all of the ratios regardless of pion energy or scattering angle, and we find that the superratio R data match very well with calculations based on the forward-hemisphere data that predicts the value of the difference between the even-nucleon radii of 3H and 3He. Comparisons are also made with recent calculations incorporating different wave functions and double scattering models.Comment: RevTex 8pages, 12 figure file

Measurement of RudsR_{\text{uds}} and RR between 3.12 and 3.72 GeV at the KEDR detector

Using the KEDR detector at the VEPP-4M $e^+e^-$ collider, we have measured the values of $R_{\text{uds}}$ and $R$ at seven points of the center-of-mass energy between 3.12 and 3.72 GeV. The total achieved accuracy is about or better than $3.3\%$ at most of energy points with a systematic uncertainty of about $2.1\%$. At the moment it is the most accurate measurement of $R(s)$ in this energy range

Search for narrow resonances in e+ e- annihilation between 1.85 and 3.1 GeV with the KEDR Detector

We report results of a search for narrow resonances in e+ e- annihilation at center-of-mass energies between 1.85 and 3.1 GeV performed with the KEDR detector at the VEPP-4M e+ e- collider. The upper limit on the leptonic width of a narrow resonance Gamma(R -> ee) Br(R -> hadr) < 120 eV has been obtained (at 90 % C.L.)

Evidence for a backward peak in the gamma+d->pi^0+d cross section near the eta threshold

High-quality cross sections for the reaction gamma+d->pi^0+d have been measured using the CLAS at Jefferson Lab over a wide energy range near and above the eta-meson photoproduction threshold. At backward c.m. angles for the outgoing pions, we observe a resonance-like structure near E_gamma=700 MeV. Our model analysis shows that it can be explained by eta excitation in the intermediate state. The effect is the result of the contribution of the N(1535)S_11 resonance to the amplitudes of the subprocesses occurring between the two nucleons and of a two-step process in which the excitation of an intermediate eta meson dominates.Comment: slightly modified title, additional paragraph and a table (Table 2) added on p. 5; to be submitted to EPJA, 6 pages, 3 figure

Search for long-living topological solutions of the nonlinear φ⁴ field theory

We look for long-living topological solutions of classical nonlinear $(1+1)-$ dimensional $\varphi^4$ field theory. To that effect we use the well-known cut-and-match method. In this framework, new long-living states are obtained in both topological sectors. In particular, in one case a highly excited state of a kink is found. We discover several ways of energy reset. In addition to the expected emission wave packets (with small amplitude), for some selected initial conditions the production of kink-antikink pairs results in a large energy reset. Also, the topological number of a kink in the central region changes in the contrast of saving full topological number. At lower excitation energies there is a long-living excited vibrational state of the kink; this phenomenon is the final stage of all considered initial states. Over time this excited state of the kink changes to a well-known linearized solution - a discrete kink excitation mode. This method yields a qualitatively new way to describe the large-amplitude bion, which was detected earlier in the kink-scattering processes in the nontopological sector.Comment: 13 pages, 11 figure