Scaling behaviours of the pTp_{T} spectra for identified hadrons in pppp collisions

We extend the scaling behaviour observed in the inclusive charged hadron transverse momentum ($p_{T}$) distributions to the $p_{T}$ spectra of pions, kaons and protons produced in proton-proton ($pp$) collisions with center of mass energies ($\sqrt{s}$ ) at 0.9, 2.76 and 7 TeV. This scaling behaviour arises when a linear transformation, $p_{T} \rightarrow p_{T}/K$, is applied on the pion, kaon or proton $p_{T}$ spectra. The scaling parameter $K$ depends on $\sqrt{s}$ and is determined by a new method, the quality factor method, which does not rely on the shape of the scaling function. We argue that the pions, kaons and protons originate from different distributions of clusters which are formed by strings overlapping, and the scaling behaviours of these identified particles $p_{T}$ spectra could be understood with the colour string percolation model in a quantitative way simultaneously.Comment: Accepted by J. Phys. G: Nucl. Part. Phys. 6 EPS figures include

Geometrical scaling of inclusive charged hadron pTp_{\rm T} spectra in Pb-Pb collsions at 2.76 TeV

In Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV, we report on a geometrical scaling in the transverse momentum ($p_{\rm T}$) spectra of inclusive charged hadrons at 0-5$\%$, 5-10$\%$, 10-20$\%$, 20-30$\%$, 30-40$\%$, 40-50$\%$, 50-60$\%$, 60-70$\%$ and 70-80$\%$ centralities. This geometrical scaling is exhibited when these spectra are expressed in terms of a new scaling variable, $p_{\rm T}^{\prime}=p_{\rm T}(191.5/N_{A})^{1/(3\lambda+6)}$, where $N_{A}$ is the number of participating nucleon pairs, $\lambda$ is the scaling parameter. With the method of ratios, this scaling parameter is determined to be 1.68. We then use a single Tsallis distribution to parameterize the spectra at different centralities, and find that the Tsallis temperature $T$ is proportional to $N_{A}^{1/(3\lambda+6)}$, which is exactly the prediction of the geometrical scaling. The geometrical scaling also predicts that the charged-particle density per participating nucleon pair ($(dN_{\rm ch}/d\eta)/N_{A}$) grows as a power of $N_{A}$, $N_{A}^{2/(3\lambda+6)}$, which is confirmed by the data collected by the ALICE collaboration.Comment: 6 pages, 5 EPS figures included. In v2, another table is added, and the fifth reference has been change

B−>πlνB -> \pi l \nu Form Factors Calculated on the Light-Front

A consistent treatment of $B\rightarrow \pi l \nu$ decay is given on the light-front. The $B$ to $\pi$ transition form factors are calculated in the entire physical range of momentum transfer for the first time. The valence-quark contribution is obtained using relativistic light-front wave functions. Higher quark-antiquark Fock-state of the $B$-meson bound state is represented effectively by the $|B^*\pi\rangle$ configuration, and its effect is calculated in the chiral perturbation theory. Wave function renormalization is taken into account consistently. The $|B^*\pi\rangle$ contribution dominates near the zero-recoil point ($q^2\simeq 25$ GeV$^2$), and decreases rapidly as the recoil momentum increases. We find that the calculated form factor $f_+(q^2)$ follows approximately a dipole $q^2$-dependence in the entire range of momentum transfer.Comment: Revtex, 19 pages, 9 figure

Scaling behavior of charged hadron pTp_{T} distributions in pppp and ppˉp\bar{p} collisions

We report on a scaling behaviour in the transverse momentum ($p_{T}$) distributions for charged hadrons produced in proton-proton ($pp$) collisions with different center of mass energies ($\sqrt{s}$ = 0.9, 2.76 and 7 TeV) at the Compact Muon Solenoid (CMS) detector. This scaling behaviour appears when the $p_{T}$ is replaced by $p_{T}/K$, where $K$ is a parameter and depends on $\sqrt{s}$. A similar scaling behaviour is observed in the $p_{T}$ distributions of charged hadrons produced in proton-antiproton ($p\bar{p}$) collisions with $\sqrt{s}$ = 0.63, 1.8 and 1.96 TeV at the Collider Detector at Fermilab (CDF). The particle production mechanism behind the scaling behaviour in the $pp$ or $p\bar{p}$ collisions could be explained by the model of percolation of strings.Comment: 10 pages in RevTeX, 5 eps figures included. Accepted by J.Phys.

Mesonic Tensor Form Factors with Light Front Quark Model

We study the tensor form factors for $P \to P$ and $P \to V$ transitions in the light-front quark model with $P$ and $V$ being pseudoscalar and vector mesons, respectively. We explore the behaviors of these form factors in the entire physical range of $0\leq p^2\leq (M_i - M_f)^2$. At the maximum recoil of $p^2=0$, we compare our results of the form factors in $B\to \pi,K,\rho,K^*$ with various other calculations in the literature.Comment: 22 pages, 4 Figures, LaTex fil

A tool framework for tweaking features in synthetic datasets

Researchers and developers use benchmarks to compare their algorithms and products. A database benchmark must have a dataset D. To be application-specific, this dataset D should be empirical. However, D may be too small, or too large, for the benchmarking experiments. D must, therefore, be scaled to the desired size. To ensure the scaled D' is similar to D, previous work typically specifies or extracts a fixed set of features F = {F_1, F_2, . . . , F_n} from D, then uses F to generate synthetic data for D'. However, this approach (D -> F -> D') becomes increasingly intractable as F gets larger, so a new solution is necessary. Different from existing approaches, this paper proposes ASPECT to scale D to enforce similarity. ASPECT first uses a size-scaler (S0) to scale D to D'. Then the user selects a set of desired features F'_1, . . . , F'_n. For each desired feature F'_k, there is a tweaking tool T_k that tweaks D' to make sure D' has the required feature F'_k. ASPECT coordinates the tweaking of T_1,...,T_n to D', so T_n(...(T_1(D'))...) has the required features F'_1,...,F'_n. By shifting from D -> F -> D' to D -> D' -> F', data scaling becomes flexible. The user can customise the scaled dataset with their own interested features. Extensive experiments on real datasets show that ASPECT can enforce similarity in the dataset effectively and efficiently

Nucleon localization and fragment formation in nuclear fission

An electron localization measure was originally introduced to characterize chemical bond structures in molecules. Recently, a nucleon localization based on Hartree-Fock densities has been introduced to investigate $\alpha$-cluster structures in light nuclei. Compared to the local nucleonic densities, the nucleon localization function has been shown to be an excellent indicator of shell effects and cluster correlations. Using the spatial nucleon localization measure, we investigate the emergence of fragments in fissioning heavy nuclei. To illustrate basic concepts of nucleon localization, we employ the self-consistent energy density functional method with a quantified energy density functional optimized for fission studies. We study the particle densities and spatial nucleon localization distributions along the fission pathways of $^{264}$Fm, $^{232}$Th and $^{240}$Pu. We demonstrate that the fission fragments are formed fairly early in the evolution, well before scission. We illustrate the usefulness of the localization measure by showing how the hyperdeformed state of $^{232}$Th can be understood in terms of a quasimolecular state made of $^{132}$Sn and $^{100}$Zr fragments. Compared to nucleonic distributions, the nucleon localization function more effectively quantifies nucleonic clustering: its characteristic oscillating pattern, traced back to shell effects, is a clear fingerprint of cluster/fragment configurations. This is of particular interest for studies of fragment formation and fragment identification in fissioning nuclei.Comment: 7 pages, 8 figure

Radio-mode feedback in local AGNs: dependence on the central black hole parameters

Radio mode feedback, in which most of the energy of an active galactic nucleus (AGN) is released in a kinetic form via radio-emitting jets, is thought to play an important role in the maintenance of massive galaxies in the present-day Universe. We study the link between radio emission and the properties of the central black hole in a large sample of local radio galaxies drawn from the Sloan Digital Sky Survey (SDSS), based on the catalogue of Best and Heckman (2012). Our sample is mainly dominated by massive black holes (mostly in the range $10^8-10^9 M_{\odot}$) accreting at very low Eddington ratios (typically $\lambda < 0.01$). In broad agreement with previously reported trends, we find that radio galaxies are preferentially associated with the more massive black holes, and that the radio loudness parameter seems to increase with decreasing Eddington ratio. We compare our results with previous studies in the literature, noting potential biases. The majority of the local radio galaxies in our sample are currently in a radiatively inefficient accretion regime, where kinetic feedback dominates over radiative feedback. We discuss possible physical interpretations of the observed trends in the context of a two-stage feedback process involving a transition in the underlying accretion modes.Comment: accepted for publication in Monthly Notices of the Royal Astronomical Societ

From Antiferromagnetism to Superconductivity: Numerical Evidence for SO(5) Symmetry

In this work, we present numerical results which support SO(5) symmetry as a concept unifying superconductivity and antiferromagnetism in the high-temperature superconductors. Using exact cluster diagonalization, we verify the recently proposed SO(5) multiplet structures for a widely used microscopic model, the t-J model. Our results show that the d-wave superconducting ground states away from half-filling are obtained from the higher spin states at half-filling through SO(5) rotations, that the dominant low energy resonance in the dynamical spin correlation function corresponds to a `pi-resonance' in the entire low doping region, and that the SO(5) symmetry is robust against inclusion of longer ranged Coulomb repulsion and next-nearest neighbor hopping.Comment: Revtex file, 7 pages and 7 eps-figure

Asymptotic expansions for distributions of compound sums of light subexponential random variables

We derive an asymptotic expansion for the distribution of a compound sum of independent random variables, all having the same light-tailed subexponential distribution. The examples of a Poisson and geometric number of summands serve as an illustration of the main result. Complete calculations are done for a Weibull distribution, with which we derive, as examples and without any difficulties, 7 terms expansions.Comment: 13 page