Cosmic-ray Monte Carlo predictions for forward particle production in p-p, p-Pb, and Pb-Pb collisions at the LHC

We present and compare the predictions of various cosmic-ray Monte Carlo models for the energy (dE/deta) and particle (dN/deta) flows in p-p, p-Pb and Pb-Pb collisions at sqrt(s) = 14, 8.8, and 5.5 TeV respectively, in the range covered by forward LHC detectors like CASTOR or TOTEM (5.2<|eta|<6.6) and ZDC or LHCf (|eta|>8.1 for neutrals).Comment: 5 pages, 5 figs. Poster proceedings Quark-Matter'08, Jaipur. To appear in Indian J. of Phy

Particle production azimuthal asymmetries in a clustering of color sources model

The collective interactions of many partons in the first stage of the collisions is the usual accepted explanation of the sizable elliptical flow. The clustering of color sources provides a framework of partonic interactions. In this scheme, we show a reasonable agreement with RHIC data for pT<1.5 GeV/c in both the dependence of v2 transverse momentum and in the shape of the nuclear modified factor on the azimuthal angle for different centralities. We show the predictions at LHC energies for Pb-Pb. In the case of proton-proton collisions a sizable v2 is obtained at this energy.Comment: To appear in Journal of Physics

Generalized Q-functions

The modulus squared of a class of wavefunctions defined on phase space is used to define a generalized family of Q or Husimi functions. A parameter lambda specifies orderings in a mapping from the operator psi)(sigma to the corresponding phase space wavefunction, where sigma is a given fiducial vector. The choice lambda = 0 specifies the Weyl mapping and the Q-function so obtained is the usual one when sigma is the vacuum state. More generally, any choice of of lambda in the range (-1,1) corresponds to orderings varying between standard and anti-standard. For all such orderings the generalized Q-functions are non-negative by construction. They are shown to be proportional to expectation of the system state rho with respect to a generalized displaced squeezed state which depends on lambda and position (p,q) in phase space. Thus, when a system has been prepared in the state rho, a generalized Q-function is proportional to the probability of finding it in the generalized squeezed state. Any such Q-function can also be written as the smoothing of the Wigner function for the system state rho by convolution with the Wigner function for the generalized squeezed state

Squeezed States of the Generalized Minimum Uncertainty State for the Caldirola-Kanai Hamiltonian

We show that the ground state of the well-known pseudo-stationary states for the Caldirola-Kanai Hamiltonian is a generalized minimum uncertainty state, which has the minimum allowed uncertainty $\Delta q \Delta p = \hbar \sigma_0/2$, where $\sigma_0 (\geq 1)$ is a constant depending on the damping factor and natural frequency. The most general symmetric Gaussian states are obtained as the one-parameter squeezed states of the pseudo-stationary ground state. It is further shown that the coherent states of the pseudo-stationary ground state constitute another class of the generalized minimum uncertainty states.Comment: RevTex4, 9 pages, no fingure; to be published in Journal of Physics

Sharpening Low-Energy, Standard-Model Tests via Correlation Coefficients in Neutron Beta-Decay

The correlation coefficients a, A, and B in neutron beta-decay are proportional to the ratio of the axial-vector to vector weak coupling constants, g_A/g_V, to leading recoil order. With the advent of the next generation of neutron decay experiments, the recoil-order corrections to these expressions become experimentally accessible, admitting a plurality of Standard Model (SM) tests. The measurement of both a and A, e.g., allows one to test the conserved-vector-current (CVC) hypothesis and to search for second-class currents (SCC) independently. The anticipated precision of these measurements suggests that the bounds on CVC violation and SCC from studies of nuclear beta-decay can be qualitatively bettered. Departures from SM expectations can be interpreted as evidence for non-V-A currents.Comment: 4 pages, REVTeX, intro. broadened, typos fixed, to appear in PR

The orbits of the quadruple star system 88 Tau A from PHASES differential astrometry and radial velocity

We have used high precision differential astrometry from the Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES) project and radial velocity measurements covering a time-span of 20 years to determine the orbital parameters of the 88 Tau A system. 88 Tau is a complex hierarchical multiple system comprising a total of six stars; we have studied the brightest 4, consisting of two short-period pairs orbiting each other with an 18-year period. We present the first orbital solution for one of the short-period pairs, and determine the masses of the components and distance to the system to the level of a few percent. In addition, our astrometric measurements allow us to make the first determination of the mutual inclinations of the orbits. We find that the sub-systems are not coplanar.Comment: Corrected Author Ordering; 12 Pages, Accepted for publication in Ap

Preformed and regenerated phosphate in ocean general circulation models: can right total concentrations be wrong?

Phosphate distributions simulated by seven state-of-the-art biogeochemical ocean circulation models are evaluated against observations of global ocean nutrient distributions. The biogeochemical models exhibit different structural complexities, ranging from simple nutrient-restoring to multi-nutrient NPZD type models. We evaluate the simulations using the observed volume distribution of phosphate. The errors in these simulated volume class distributions are significantly larger when preformed phosphate (or regenerated phosphate) rather than total phosphate is considered. Our analysis reveals that models can achieve similarly good fits to observed total phosphate distributions for a very different partitioning into preformed and regenerated nutrient components. This has implications for the strength and potential climate sensitivity of the simulated biological carbon pump. We suggest complementing the use of total nutrient distributions for assessing model skill by an evaluation of the respective preformed and regenerated nutrient components

Measurement of zero degree single photon energy spectra for sqrt(s) = 7TeV proton-proton collisions at LHC

In early 2010, the Large Hadron Collider forward (LHCf) experiment measured very forward neutral particle spectra in LHC proton-proton collisions. From a limited data set taken under the best beam conditions (low beam-gas background and low occurance of pile-up events), the single photon spectra at sqrt(s)=7TeV and pseudo-rapidity (eta) ranges from 8.81 to 8.99 and from 10.94 to infinity were obtained for the first time and are reported in this paper. The spectra from two independent LHCf detectors are consistent with one another and serve as a cross check of the data. The photon spectra are also compared with the predictions of several hadron interaction models that are used extensively for modeling ultra high energy cosmic ray showers. Despite conservative estimates for the systematic errors, none of the models agree perfectly with the measurements. A notable difference is found between the data and the DPMJET 3.04 and PYTHIA 8.145 hadron interaction models above 2TeV where the models predict higher photon yield than the data. The QGSJET II-03 model predicts overall lower photon yield than the data, especially above 2TeV in the rapidity range 8.81<eta<8.99

Wii-Fit for Improving Gait and Balance in an Assisted Living Facility: A Pilot Study

Objectives. To determine the effects on balance and gait of a Wii-Fit program compared to a walking program in subjects with mild Alzheimer's dementia (AD). Methods. A prospective randomized (1 : 1) pilot study with two intervention arms was conducted in an assisted living facility with twenty-two mild AD subjects. In both groups the intervention occurred under supervision for 30 minutes daily, five times a week for eight weeks. Repeated measures ANOVA and paired t-tests were used to analyze changes. Results. Both groups showed improvement in Berg Balance Scale (BBS), Tinetti Test (TT) and Timed Up and Go (TUG) over 8 weeks. However, there was no statistically significant difference between the groups over time. Intragroup analysis in the Wii-Fit group showed significant improvement on BBS (P = 0.003), and TT (P = 0.013). The walking group showed a trend towards improvement on BBS (P = 0.06) and TUG (P = 0.07) and significant improvement in TT (P = 0.06). Conclusion. This pilot study demonstrates the safety and efficacy of Wii-Fit in an assisted living facility in subjects with mild AD. Use of Wii-Fit resulted in significant improvements in balance and gait comparable to those in the robust monitored walking program. These results need to be confirmed in a larger, methodologically sound study