14104948
Two particle states in an asymmetric box and the elastic scattering phases
The exact two-particle energy eigenstates in a generic asymmetric rectangular box with periodic boundary conditions in all three directions are studied. Their relations with the elastic scattering phases of the two particles in the continuum are obtained for both ${D}_{4}$ and ${D}_{2}$ symmetries. These results can be viewed as a generalization of the corresponding formulas in a cubic box obtained by L\"uscher before. In particular, the s-wave scattering length is related to the energy shift in the finite box. Possible applications of these formulas are also discussed.
119273385
Symmetry and special relativity in Finsler spacetime with constant curvature
Within the framework of projective geometry, we investigate kinematics and symmetry in (alpha, beta) spacetime one special types of Finsler spacetime. The projectively flat (alpha, beta) spacetime with constant flag curvature is divided into four types. The symmetry in type A-Riemann spacetime with constant sectional curvature-is just the one in de Sitter special relativity. The symmetry in type B-locally Minkowski spacetime-is just the one in very special relativity. It is found that type C-Funk spacetime and type D-scaled Berwald's metric spacetime both possess the Lorentz group as its isometric group. The geodesic equation, algebra and dispersion relation in the (alpha, beta) spacetime are given. The corresponding invariant special relativity in the four types of (alpha, beta) spacetime contain two parameters, the speed of light and a geometrical parameter, which may relate to the new physical scale. They all reduce to Einstein's special relativity while the geometrical parameter vanishes. (C) 2012 Elsevier B.V. All rights reserved.
15016243
A Possible scenario of the Pioneer anomaly in the framework of Finsler geometry
The weak field approximation of geodesics in Randers-Finsler space is investigated. We show that a Finsler structure of Randers space corresponds to the constant and sunward anomalous acceleration demonstrated by the Pioneer 10 and 11 data. The additional term in the geodesic equation acts as "electric force", which provides the anomalous acceleration. (C) 2010 Elsevier B.V. All rights reserved.
118130623
Quantum resonance scheme to measure the gravitational constant G
14726570
Massive domain wall fermions on four-dimensional anisotropic lattices
We formulate the massive domain wall fermions on anisotropic lattices. For the massive domain wall fermion, we find that the dispersion relation assumes the usual form in the low momentum region when the bare parameters are properly tuned. The quark self-energy and the quark field renormalization constants are calculated to one-loop in bare lattice perturbation theory. For light domain wall fermions, we verified that the chiral mode is stable against quantum fluctuations on anisotropic lattices. This calculation serves as a guidance for the tuning of the parameters in the quark action in future numerical simulations.
118861755
Constraints from Type IA Supernovae on {\lambda}-CDM Model in Randers-Finsler Space
Abstract Gravitational field equations in Randers-Finsler space of approximate Berwald type are investigated. A modified Friedmann equation and a new luminosity distance-redshift relation is proposed. A best-fit to the Type Ia supernovae (SNe) observations yields that the ΩΛ in the Λ-CDM model is suppressed to almost zero. This fact indicates that the astronomical observations on the Type Ia SNe can be described well without invoking any form of dark energy. The best-fit age of the universe is given. It is in agreement with the age of our galaxy.
195859510
Front-end electronics for PHENIX time expansion chamber
Front-end electronics (FEE) has been developed for the PHENIX time expansion chamber (TEC), a multi-wire tracking detector with over 20k readout channels. The FEE for the TEC consists of an analog preamplifier shaping amplifier circuit board, a digital front-end module circuit board plus ancillary support boards for timing, control and communication. Signals from each chamber wire are sampled (/spl sim/40 MHz), digitized, buffered, and then formatted as 64 channel serial data packets to be transmitted via 1 GHz optical link. Three custom IC's have been designed for this system: 1) octal preamplifier and shaping amplifier with tail cancellation and dual-gain for large dynamic range with full serial control of gain, shaping time and tail; 2) nonlinear 5 bit flash-ADC with 9 bit dynamic range; 3) digital memory unit for programmable delay and memory depth. The FEE has been installed, commissioned and operated in the PHENIX experiment at Brookhaven National Laboratory.
118442016
Extracting the nuclear symmetry potential and energy from neutron-nucleus scattering data
Abstract According to the Hugenholtz–Van Hove theorem, the symmetry energy and its density slope can be decomposed uniquely in terms of the single-nucleon potential in asymmetric nuclear matter which, at normal density, can be constrained by the nucleon optical model potential extracted from analyzing the nucleon–nucleus scattering data. To more accurately extract information on the symmetry energy and its density slope at normal density from neutron–nucleus scattering data, going beyond the well-known Lane potential, we include consistently the second-order terms in isospin asymmetry in both the optical model potential and the symmetry energy decomposition. We find that the strength of the second-order symmetry potential U sym , 2 in asymmetric nuclear matter is significant compared to the first-order one U sym , 1 , especially at high nucleon momentum. While the U sym , 1 at normal density decreases with nucleon momentum, the U sym , 2 is found to have the opposite behavior. Moreover, we discuss effects of the U sym , 1 and U sym , 2 on determining the density dependence of the symmetry energy, and we find that the available neutron–nucleus scattering data favor a softer density dependence of the symmetry energy at normal density with a negligible contribution from the U sym , 2 .
1941882
Reexamining charmless B ---> PV decays in QCD factorization approach
Using the QCD factorization approach, we reexamine the two-body hadronic charmless $B$-meson decays to final states involving a pseudoscalar~($P$) and a vector~($V$) meson, with inclusion of the penguin contractions of spectator-scattering amplitudes induced by the $b\to D g^\ast g^\ast$~(where $D=d$ or $s$, and $g^\ast$ denotes an off-shell gluon) transitions, which are of order $\alpha_s^2$. Their impacts on the CP-averaged branching ratios and CP-violating asymmetries are examined. We find that these higher order penguin contraction contributions have significant impacts on some specific decay modes. Since $B\to \pi K^{\ast}$, $K \rho$ decays involve the same electro-weak physics as $B\to \pi K$ puzzles, we present a detailed analysis of these decays and find that the five R-ratios for $B\to \pi K^{\ast}$, $K \rho$ system are in agreement with experimental data except for $R(\pi K^*)$. Generally, these new contributions are found to be important for penguin-dominated $B\to PV$ decays.
118446762
Neutron–proton effective mass splitting in neutron-rich matter at normal density from analyzing nucleon–nucleus scattering data within an isospin dependent optical model
Abstract The neutron–proton effective mass splitting in asymmetric nucleonic matter of isospin asymmetry δ and normal density is found to be m n − p ⁎ ≡ ( m n ⁎ − m p ⁎ ) / m = ( 0.41 ± 0.15 ) δ from analyzing globally 1088 sets of reaction and angular differential cross sections of proton elastic scattering on 130 targets with beam energies from 0.783 MeV to 200 MeV, and 1161 sets of data of neutron elastic scattering on 104 targets with beam energies from 0.05 MeV to 200 MeV within an isospin dependent non-relativistic optical potential model. It sets a useful reference for testing model predictions on the momentum dependence of the nucleon isovector potential necessary for understanding novel structures and reactions of rare isotopes.
117323209
Search for GRB counterparts using the ARGO‐YBJ experiment in shower mode
In this paper, the effective area of the ARGO‐YBJ experiment to detect the gamma rays with energy range from 10 GeV to 1 TeV for different incident zenith angles (0,10,20,30,40 degrees) is given respectively. The optimal event selections to search for GRB counterparts with different cutoff energy models (Ecut = 100 GeV and 1 TeV) are studied. Using these selections and their corresponding angular resolutions the searches are done within two hours around the GRB trigger time via different time windows. Finally, the result for the 20 GRBs in the field of view of ARGO between July 2006 and July 2008 is presented, and the fluence upper limit for each GRB is set at 99% confidence level.