119490122
Isospin influences on particle emission and critical phenomena in nuclear dissociation
Features of particle emission and critical point behavior are investigated as functions of the isospin of disassembling sources and temperature at a moderate freeze-out density far medium-size Xe isotopes in the framework of the isospin-dependent lattice gas model. Multiplicities of emitted light particles, isotopic, and isobaric ratios of light particles show the strong dependence on the isospin of the dissociation source, but double ratios of light isotope pairs and the critical temperature determined by the extreme values of some critical observables are insensitive to the isospin of the systems. Values of the power law parameter of cluster mass distribution, mean multiplicity of intermediate mass fragments (IMF), information entropy, and Campi's second moment also show a minor dependence on the isospin of Xe isotopes at the critical point. In addition, the slopes of the average multiplicities of the neutrons (N-n), protons (N-p), charged particles (N-CP), and IMFs (N-IMF), slopes of the largest fragment mass number (A(max)), and the excitation energy per nucleon of the disassembling source (E*/A) to temperature are investigated as well as variances of the distributions of N-n, N-p, N-CP, N-IMF, A(max), and E*/A. It is found that they can be taken as additional judgements to the critical phenomena. [S0556-2813(99)302108-1].
123463436
Isospin Effect of Fragmentation Reaction on the Isotopic Distribution Produced in Intermediate Energy Heavy Ion Collisions
Fragments produced in the reaction of 60MeV/n O-18 On Be have been measured experimentally. The isotopic distribution of fragmentation reaction is well reproduced by a modified statistical abrasion-ablation model. It is predicted that the isotopic distribution shifts toward the neutron rich side for neutron rich projectile, but this isospin effect decreases with the increase of the atomic number difference Z - Z(A) and disappears at last, where Z and Z(A) are atomic numbers of the isotopic distribution and the projectile respectively.
123856190
Existence of a proton halo in Al-23 and its significance
Reaction cross section sigma(R) of proton-rich isotones (N = 10) near Al-23 and Al isotopes (Al23-28) on C target have been measured at intermediate energies around 30 MeV/nucleon. An abnormal increase of the experimental sigma(R) is observed for Al-23 and it suggests that there is an anomalously large matter rms radius in Al-23. Together with the very weakly binding of the last proton (S-p = 0.125 MeV), it indicates that there is a proton halo in Al-23. This conclusion is also supported by the difference factor d which is deduced from the measured and theoretical sigma(R) in the Glauber or Boltzmann-Uehling-Uhlenbeck model and is used for the manifest of halo phenomena. The theoretical calculation based,on the relativistic density dependent Hartree model shows that there is a proton halo when the last proton is in the 2s(1/2) orbit in Al-23. The significance of the proton halo in Al-23 is discussed.
53131397
Energy and system-size dependence of two- and four-particle $v_2$ measurements in heavy-ion collisions at RHIC and their implications on flow fluctuations and nonflow
We present STAR measurements of azimuthal anisotropy by means of the two- and four-particle cumulants $v_2$ ($v_2\{2\}$ and $v_2\{4\}$) for Au+Au and Cu+Cu collisions at center of mass energies $\sqrt{s_{_{\mathrm{NN}}}} = 62.4$ and 200 GeV. The difference between $v_2\{2\}^2$ and $v_2\{4\}^2$ is related to $v_{2}$ fluctuations ($\sigma_{v_2}$) and nonflow $(\delta_{2})$. We present an upper limit to $\sigma_{v_2}/v_{2}$. Following the assumption that eccentricity fluctuations $\sigma_{\epsilon}$ dominate $v_2$ fluctuations $\frac{\sigma_{v_2}}{v_2} \approx \frac{\sigma_{\epsilon}}{\epsilon}$ we deduce the nonflow implied for several models of eccentricity fluctuations that would be required for consistency with $v_2\{2\}$ and $v_2\{4\}$. We also present results on the ratio of $v_2$ to eccentricity.
119972193
Measurements of total reaction cross sections for some light nuclei at intermediate energies
Measurements of the total reaction cross section for C12-16, N14-17, and O16-18 on carbon target at intermediate energies were performed on the Radioactive Ion Beam Line of the Heavy ion Research Facility in Lanzhou. A larger enhancement of sigma(R) for C-15 was observed than for its neighbors. Evidence for possible anomalous nuclear structure in C-15 was revealed in the analysis of the total reaction cross section in terms of the difference factor d.
123342853
Azimuthal distribution, azimuthal correlation, and reaction plane dispersion in the reaction 10.6 MeV/nucleon Kr-84 on Al-27
The azimuthal distribution and azimuthal correlation of the emitted light charge particles in coincidence with the forward-going heavy fragments in the reaction of 10.6 MeV/nucleon Kr-84 on Al-27 have been studied in detail. A novel way to extract the reaction plane dispersion by combining the azimuthal distribution constructed using the experimental measured reaction plane which contains a reaction plane dispersion and a two-particle azimuthal correlation which is free of reaction plane dispersion was described. This method was applied to the low-energy fission reaction Kr-84+Al-27 at 10.6 MeV/nucleon for light particles, p and alpha, with success.
118146782
Amplitude analysis and the branching fraction measurement of $\bar{B}^0_s \to J/\psi K^+K^-$
An amplitude analysis of the final state structure in the Bs0→J/ψK+K- decay mode is performed using 1.0  fb-1 of data collected by the LHCb experiment in 7 TeV center-of-mass energy pp collisions produced by the LHC. A modified Dalitz plot analysis of the final state is performed using both the invariant mass spectra and the decay angular distributions. Resonant structures are observed in the K+K- mass spectrum as well as a significant non-resonant S-wave contribution over the entire K+K- mass range. The largest resonant component is the ϕ(1020), accompanied by f0(980), f2′(1525), and four additional resonances. The overall branching fraction is measured to be B(Bs0→J/ψK+K-)=(7.70±0.08±0.39±0.60)×10-4, where the first uncertainty is statistical, the second systematic, and the third due to the ratio of the number of Bs0 to B- mesons produced. The mass and width of the f2′(1525) are measured to be 1522.2±2.8-2.0+5.3  MeV and 84±6-5+10  MeV, respectively. The final state fractions of the other resonant states are also reported.
118274966
Search for electroweak production of charginos and neutralinos using leptonic final states in pp collisions at $ \sqrt{s}=7 $ TeV
A bstractThe 2011 dataset of the CMS experiment, consisting of an integrated luminosity of 4.98 fb−1 of pp collisions at $ \sqrt{s}=7 $ TeV, enables expanded searches for direct electroweak pair production of charginos and neutralinos in supersymmetric models as well as their analogs in other models of new physics. Searches sensitive to such processes, with decays to final states that contain two or more leptons, are presented. Final states with three leptons, with a same-sign lepton pair, and with an opposite-sign lepton pair in conjunction with two jets, are examined. No excesses above the standard model expectations are observed. The results are used in conjunction with previous results on four-lepton final states to exclude a range of chargino and neutralino masses from approximately 200 to 500 GeV in the context of models that assume large branching fractions of charginos and neutralinos to leptons and vector bosons.
118660389
TWO-PHASE ICM IN THE CENTRAL REGION OF THE RICH CLUSTER OF GALAXIES A1795: A JOINT CHANDRA, XMM-NEWTON, AND SUZAKU VIEW
Based on a detailed analysis of the high-quality Chandra, XMM-Newton, and Suzaku data of the X-ray bright cluster of galaxies A1795, we report clear evidence for a two-phase intracluster medium (ICM) structure, which consists of a cool (with a temperature T-c approximate to 2.0-2.2 keV) and a hot (T-h approximate to 5.0-5.7 keV) component that coexist and dominate the X-ray emission at least in the central 80 kpc. A third weak emission component (T-3 approximate to 0.8 keV) is also detected within the innermost 144 kpc and is ascribed to a portion of interstellar medium of the cD galaxy. Deprojected spectral analysis reveals flat radial temperature distributions for both the hot phase and cool phase components. These results are consistent with the ASCA measurements reported by Xu et al. and resemble the previous findings for the Centaurus Cluster. By analyzing the emission measure ratio and gas metal abundance maps created from the Chandra data, we find that the cool phase component is more metal-enriched than the hot phase one in the 50-100 kpc region, which agrees with that found in M87. The coexistence of the cool phase and hot phase ICM cannot be realized by bubble uplifting from active galactic nuclei (AGNs) alone. Instead, the two-phase ICM properties are better reconciled with a cD corona model. In this model, the cool phase may be ascribed to the plasmas confined in magnetic loops, which are surrounded by the intruding hot phase ICM and have been polluted by metals synthesized in the cD galaxy. AGN feedback energy released in the innermost 10 kpc can serve as the heating source to prevent the loop-interior gas from cooling down to temperatures much lower than the observed value. The total gravitating mass profile exhibits a hierarchical structure, regardless of the ICM temperature modeling.
7377062
Gauge invariant effective Lagrangian for Kaluza-Klein modes
We construct a manifestly gauge invariant Lagrangian in $3+1$ dimensions for N Kaluza-Klein modes of an $\mathrm{SU}(m)$ gauge theory in the bulk. For example, if the bulk is $4+1,$ the effective theory is ${\ensuremath{\Pi}}_{i=1}^{N+1}{\mathrm{SU}(m)}_{i}$ with N chiral $(\overline{m},m)$ fields connecting the groups sequentially. This can be viewed as a Wilson action for a transverse lattice in ${x}^{5},$ and is shown explicitly to match the continuum $4+1$ compactified Lagrangian truncated in momentum space. Scale dependence of the gauge couplings is described by the standard renormalization group technique with threshold matching, leading to effective power law running. We also discuss the unitarity constraints, and chiral fermions.
15099712
Dark energy model with spinor matter and its quintom scenario
A class of dynamical dark energy models, dubbed spinor quintom, can be constructed by a spinor field psi with a nontraditional potential. We find that, if choosing suitable potential, this model is able to allow the equation-of-state to cross the cosmological constant boundary without introducing any ghost fields. In a further investigation, we show that this model is able to mimic a perfect fluid of Chaplygin gas with p = -c/rho during the evolution, and also realizes the quintom scenario with its equation-of-state across -1.