Sum rules for four-spinon dynamic structure factor in XXX model

In the context of the antiferromagnetic spin 1/2 Heisenberg quantum spin chain (XXX model), we estimate the contribution of the exact four-spinon dynamic structure factor $S_4$ by calculating a number of sum rules the total dynamic structure factor $S$ is known to satisfy exactly. These sum rules are: the static susceptibility, the integrated intensity, the total integrated intensity, the first frequency moment and the nearest-neighbor correlation function. We find that the contribution of $S_4$ is between 1% and 2.5%, depending on the sum rule, whereas the contribution of the exact two-spinon dynamic structure factor $S_2$ is between 70% and 75%. This is consistent with the expected scattering weight of states from outside the spin-wave continuum. The calculations are numerical and Monte Carlo based. Good statistics are obtained.Comment: 21 pages, Revtex, 02 figure

Quantum criticality in spin chains with non-ohmic dissipation

We investigate the critical behavior of a spin chain coupled to bosonic baths characterized by a spectral density proportional to $\omega^s$, with $s>1$. Varying $s$ changes the effective dimension $d_\text{eff} = d + z$ of the system, where $z$ is the dynamical critical exponent and the number of spatial dimensions $d$ is set to one. We consider two extreme cases of clock models, namely Ising-like and U(1)-symmetric ones, and find the critical exponents using Monte Carlo methods. The dynamical critical exponent and the anomalous scaling dimension $\eta$ are independent of the order parameter symmetry for all values of $s$. The dynamical critical exponent varies continuously from $z \approx 2$ for $s=1$ to $z=1$ for $s=2$, and the anomalous scaling dimension evolves correspondingly from $\eta \gtrsim 0$ to $\eta = 1/4$. The latter exponent values are readily understood from the effective dimensionality of the system being $d_\text{eff} \approx 3$ for $s=1$, while for $s=2$ the anomalous dimension takes the well-known exact value for the 2D Ising and XY models, since then $d_{\rm{eff}}=2$. A noteworthy feature is, however, that $z$ approaches unity and $\eta$ approaches 1/4 for values of $s < 2$, while naive scaling would predict the dissipation to become irrelevant for $s=2$. Instead, we find that $z=1,\eta=1/4$ for $s \approx 1.75$ for both Ising-like and U(1) order parameter symmetry. These results lead us to conjecture that for all site-dissipative $Z_q$ chains, these two exponents are related by the scaling relation $z = \text{max} {(2-\eta)/s, 1}$. We also connect our results to quantum criticality in nondissipative spin chains with long-range spatial interactions.Comment: 8 pages, 6 figure

Top quark spin correlations at hadron colliders: Predictions at next-to-leading order QCD

The collider experiments at the Tevatron and the LHC will allow for detailed investigations of the properties of the top quark. This requires precise predictions of the hadronic production of $t\bar t$ pairs and of their subsequent decays. In this Letter we present for the reactions $p {\bar p}, p p \to t{\bar t} + X \to \ell^+\ell'^-X$ the first calculation of the dilepton angular distribution at next-to-leading order (NLO) in the QCD coupling, keeping the full dependence on the spins of the intermediate $t\bar{t}$ state. The angular distribution reflects the degree of correlation of the $t$ and $\bar t$ spins which we determine for different choices of $t$ and $\bar t$ spin bases. In the case of the Tevatron, the QCD corrections are sizeable, and the distribution is quite sensitive to the parton content of the proton.Comment: 9 pages, 2 figure

Production rates for hadrons, pentaquarks Θ+\Theta ^+ and Θ∗++\Theta ^{*++}, and di-baryon (ΩΩ)0+(\Omega\Omega)_{0^{+}} in relativistic heavy ion collisions by a quark combination model

The hadron production in relativistic heavy ion collisions is well described by the quark combination model. The mixed ratios for various hadrons and the transverse momentum spectra for long-life hadrons are predicted and agree with recent RHIC data. The production rates for the pentaquarks $\Theta ^+$, $\Theta ^{*++}$ and the di-baryon $(\Omega\Omega)_{0^{+}}$ are estimated, neglecting the effect from the transition amplitude for constituent quarks to form an exotic state.Comment: The difference between our model and other combination models is clarified. The scaled transverse momentum spectra for pions, kaons and protoms at both 130 AGeV and 200 AGeV are given, replacing the previous results in transverse momentum spectr

The suppression of hidden order and onset of ferromagnetism in URu2Si2 via Re substitution

Substitution of Re for Ru in the heavy fermion compound URu2Si2 suppresses the hidden order transition and gives rise to ferromagnetism at higher concentrations. The hidden order transition of URu(2-x)Re(x)Si2, tracked via specific heat and electrical resistivity measurements, decreases in temperature and broadens, and is no longer observed for x>0.1. A critical scaling analysis of the bulk magnetization indicates that the ferromagnetic ordering temperature and ordered moment are suppressed continuously towards zero at a critical concentration of x = 0.15, accompanied by the additional suppression of the critical exponents gamma and (delta-1) towards zero. This unusual trend appears to reflect the underlying interplay between Kondo and ferromagnetic interactions, and perhaps the proximity of the hidden order phase.Comment: 8 pgs, 5 figs, ICM 2009; please refer to Phys. Rev. Lett. 103, 076404 (2009), arXiv:0908.1809 for details on magnetic scaling and phase diagram (reference added to this version

Top Quark Pair Production and Decay including Spin Effects at Hadron Colliders: Predictions at NLO QCD

Top quark-antiquark ($t\bar t$) pairs will be produced copiously at the Tevatron collider and in huge numbers at the LHC. This will make possible detailed investigations of the properties and interactions of this quark flavor. The analysis and interpretation of future data requires precise predictions of the hadronic production of $t\bar t$ pairs and of their subsequent decays. In this talk the reactions $p {\bar p}, p p \to t{\bar t} + X \to l^+ l'^- + X$ are considered and results are presented of our calculation of the dilepton angular distribution at next-to-leading order QCD, keeping the full dependence on the spins of the intermediate $t\bar{t}$ state. The angular distribution is determined for different choices of reference axes that can be identified with the $t$ and $\bar t$ spin axes. While the QCD corrections to the leading-order distribution turn out to be small in the case of the LHC, we find them to be sizeable in the case of the Tevatron and find, moreover, the angular distribution to be sensitive to the parton content of the proton.Comment: Talk given at 3rd Circum-Pan-Pacific Symposium on "High Energy Spin Physics", Beijing, China, 8-13, 200

Study the Heavy Molecular States in Quark Model with Meson Exchange Interaction

Some charmonium-like resonances such as X(3872) can be interpreted as possible $D^{(*)}D^{(*)}$ molecular states. Within the quark model, we study the structure of such molecular states and the similar $B^{(*)}B^{(*)}$ molecular states by taking into account of the light meson exchange ($\pi$, $\eta$, $\rho$, $\omega$ and $\sigma$) between two light quarks from different mesons

Implementasi Lesson Study pada Mata Pelajaran Ekonomi dalam Menanamkan Kemandirian dan Sikap Kewirausahaan Siswa SMA di Kabupaten Pacitan Tahun Pelajaran 2012/2013

Tujuan penelitian ini adalah untuk mengetahui efektifitas implementasi Lesson Study pada mata pelajaran ekonomi di SMA, untuk mengetahui kemandirian siswa SMA pada mata pelajaran ekonomi, untuk mengetahui sikap kewirausahaan siswa di SMA pada mata pelajaran ekonomi. Data penelitian yang diambil data primer. Metode penelitian berbentuk deskriptif kualitatif. Populasi penelitian adalah seluruh siswa SMA Negeri 1 Ngadirojo dan SMA Negeri 2 Ngadirojo di Kabupaten Pacitan. Teknik pengambilan sampel menggunakan simple random sampling. Teknik analisis data yang digunakan melalui pemaparan data, reduksi data, kategorisasi data, penafsiran/pemaknaan, dan penyimpulan hasil analisis. Teknik pengumpulan data yaitu wawancara, observasi, angket, dan dokumentasi.Hasil penelitian menunjukkan bahwa Lesson Study sangat efektif dalam meningkatkan proses pembelajaran siswa dan aktivitas guru. Lesson Study efektif untuk menanamkan kemandirian siswa. Lesson Study dapat menumbuhkan sikap kewirausahaan pada siswa

Pengaruh Tenaga Kerja, Teknologi, dan Modal dalam Meningkatkan Produksi di Industri Pengolahan Garam Kabupaten Pati

The objective of this research is to investigate whether there is an effect of manpower, technology, and capital on the salt production improvement at salt processing industry of Pati regency. This research used the descriptive quantitative research method. The population of the research 58 persons in Pati regency. The samples consisted of 40 entrepreneurs. The data used were primary data, whick were collected through questionnaire. They study uses multiple regression analys. The results of the research the t test shows that the significance value is 0.005, meaning that the variables of manpower, technology, and capital partially have a significant effect on the salt production. The F test shows the significance value of 0.000 is smaller than that of the significance value of t test = 0.005, indicating that the variables of manpower, technology, and capital have a significant effect on the salt production. The value of R2 is 0.645 meaning that 64.5% of the salt production variations can be verified by the independent variables (manpower, technology, and capital), and the rest 35.4% are verified by other variables outside the regression model. Based on the results of the research it can be concluded that manpower, technology, and capital have a simultaneously significant effect on the salt production improvement at salt processing industry of Pati regency. In order to improve salt production it is suggested that the producers of salt should pay attention to the iodized salt quality in accordance with the SNI standards; and be manpower guidance and training as well as appropriate technology use at the salt industries shall be conducted