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Articles 31 - 60 of 557
Full-Text Articles in Physics
Memory Formation In Matter, Joseph Paulsen, Nathan C. Keim, Zorana Zeravcic, Srikanth Sastry, Sidney R. Nagel
Memory Formation In Matter, Joseph Paulsen, Nathan C. Keim, Zorana Zeravcic, Srikanth Sastry, Sidney R. Nagel
Physics - All Scholarship
Memory formation in matter is a theme of broad intellectual relevance; it sits at the interdisciplinary crossroads of physics, biology, chemistry, and computer science. Memory connotes the ability to encode, access, and erase signatures of past history in the state of a system. Once the system has completely relaxed to thermal equilibrium, it is no longer able to recall aspects of its evolution. The memory of initial conditions or previous training protocols will be lost. Thus many forms of memory are intrinsically tied to far-from-equilibrium behavior and to transient response to a perturbation. This general behavior arises in diverse contexts …
The Propagation Of Active-Passive Interfaces In Bacterial Swarms, Alison E. Patteson, Arvind Gopinath, Paulo E. Arratia
The Propagation Of Active-Passive Interfaces In Bacterial Swarms, Alison E. Patteson, Arvind Gopinath, Paulo E. Arratia
Physics - All Scholarship
Propagating interfaces are ubiquitous in nature, underlying instabilities and pattern formation in biology and material science. Physical principles governing interface growth are well understood in passive settings; however, our understanding of interfaces in active systems is still in its infancy. Here, we study the evolution of an active-passive interface using a model active matter system, bacterial swarms. We use ultra-violet light exposure to create compact domains of passive bacteria within Serratia marcescens swarms, thereby creating interfaces separating motile and immotile cells. Post-exposure, the boundary re-shapes and erodes due to self-emergent collective flows. We demonstrate that the active-passive boundary acts as …
Hyperuniformity With No Fine Tuning In Sheared Sedimenting Suspensions, Joseph Paulsen, J. M. Schwarz, Jikai Wang
Hyperuniformity With No Fine Tuning In Sheared Sedimenting Suspensions, Joseph Paulsen, J. M. Schwarz, Jikai Wang
Physics - All Scholarship
Particle suspensions, present in many natural and industrial settings, typically contain aggregates or other microstructures that can complicate macroscopic flow behaviors and damage processing equipment. Recent work found that applying uniform periodic shear near a critical transition can reduce fluctuations in the particle concentration across all length scales, leading to a hyperuniform state. However, this strategy for homogenization requires fine tuning of the strain amplitude. Here we show that in a model of sedimenting particles under periodic shear, there is a well-defined regime at low sedimentation speed where hyperuniform scaling automatically occurs. Our simulations and theoretical arguments show that the …
Geometry-Driven Folding Of A Floating Annular Sheet, Joseph Paulsen, Vincent Démery, K. Buğra Toga, Zhanlong Qiu, Thomas P. Russell, Benny Davidovitch, Narayanan Menon
Geometry-Driven Folding Of A Floating Annular Sheet, Joseph Paulsen, Vincent Démery, K. Buğra Toga, Zhanlong Qiu, Thomas P. Russell, Benny Davidovitch, Narayanan Menon
Physics - All Scholarship
Predicting the large-amplitude deformations of thin elastic sheets is difficult due to the complications of self contact, geometric nonlinearities, and a multitude of low-lying energy states. We study a simple twodimensional setting where an annular polymer sheet floating on an air-water interface is subjected to different tensions on the inner and outer rims. The sheet folds and wrinkles into many distinct morphologies that break axisymmetry. These states can be understood within a recent geometric approach for determining the gross shape of extremely bendable yet inextensible sheets by extremizing an appropriate area functional. Our analysis explains the remarkable feature that the …
Electron And Hole Drift Mobility Measurements On Methylammonium Lead Iodide Perovskite Solar Cells, Brian Maynard, Qi Long, Eric A. Schiff, Mengjin Yang, Kai Zhu, Ranjith Kottokkaran, Hisham Abbas, Vikram L. Dalal
Electron And Hole Drift Mobility Measurements On Methylammonium Lead Iodide Perovskite Solar Cells, Brian Maynard, Qi Long, Eric A. Schiff, Mengjin Yang, Kai Zhu, Ranjith Kottokkaran, Hisham Abbas, Vikram L. Dalal
Physics - All Scholarship
We report nanosecond domain time-of-flight measurements of electron and hole photocarriers in methylammonium lead iodide perovskite solar cells. The mobilities ranged from 0.06 to 1.4 cm2/Vs at room temperature, but there is little systematic difference between the two carriers. We also find that the drift mobilities are dispersive (time-dependent). The dispersion parameters are in the range of 0.4–0.7, and they imply that terahertz domain mobilities will be much larger than nanosecond domain mobilities. The temperature-dependences of the dispersion parameters are consistent with confinement of electron and hole transport to fractal-like spatial networks within nanoseconds of their photogeneration.
Active Colloids In Complex Fluids, Alison E. Patteson, Arvind Gopinath, Paulo E. Arratia
Active Colloids In Complex Fluids, Alison E. Patteson, Arvind Gopinath, Paulo E. Arratia
Physics - All Scholarship
We review recent work on active colloids or swimmers, such as self-propelled microorganisms, phoretic colloidal particles, and artificial micro-robotic systems, moving in fluid-like environments. These environments can be water-like and Newtonian but can frequently contain macromolecules, flexible polymers, soft cells, or hard particles, which impart complex, nonlinear rheological features to the fluid. While significant progress has been made on understanding how active colloids move and interact in Newtonian fluids, little is known on how active colloids behave in complex and non-Newtonian fluids. An emerging literature is starting to show how fluid rheology can dramatically change the gaits …
Particle Diffusion In Active Fluids Is Non-Monotonic In Size, Alison E. Patteson, Arvind Gopinath, Prashant K. Purohit, Paulo E. Arratia
Particle Diffusion In Active Fluids Is Non-Monotonic In Size, Alison E. Patteson, Arvind Gopinath, Prashant K. Purohit, Paulo E. Arratia
Physics - All Scholarship
We experimentally investigate the effect of particle size on the motion of passive polystyrene spheres in suspensions of Escherichia coli. Using particles covering a range of sizes from 0.6 to 39 microns, we probe particle dynamics at both short and long time scales. In all cases, the particles exhibit super-diffusive ballistic behavior at short times before eventually transitioning to diffusive behavior. Surprisingly, we find a regime in which larger particles can diffuse faster than smaller particles: the particle long-time effective diffusivity exhibits a peak in particle size, which is a deviation from classical thermal diffusion. We also find that …
Curvature-Induced Stiffness And The Spatial Variation Of Wavelength In Wrinkled Sheets, Joseph Paulsen, Evan Hohlfeld, Hunter King, Jiangshui Huang, Zhanglong Qiu, Thomas P. Russell, Narayanan Menon, Dominic Vella, Benny Davidovitch
Curvature-Induced Stiffness And The Spatial Variation Of Wavelength In Wrinkled Sheets, Joseph Paulsen, Evan Hohlfeld, Hunter King, Jiangshui Huang, Zhanglong Qiu, Thomas P. Russell, Narayanan Menon, Dominic Vella, Benny Davidovitch
Physics - All Scholarship
Wrinkle patterns in compressed thin sheets are ubiquitous in nature and technology, from the furrows on our foreheads to crinkly plant leaves, from ripples on plastic-wrapped objects to the protein film on milk. The current understanding of an elementary descriptor of wrinkles—their wavelength—is restricted to deformations that are parallel, spatially uniform, and nearly planar. However, most naturally occurring wrinkles do not satisfy these stipulations. Here we present a scheme that quantitatively explains the wrinkle wavelength beyond such idealized situations. We propose a local law that incorporates both mechanical and geometrical effects on the spatial variation of wrinkle wavelength. Our experiments …
Running And Tumbling With E. Coli In Polymeric Solutions, Alison E. Patteson, Arvind Gopinath, Mark Goulian, Paulo E. Arratia
Running And Tumbling With E. Coli In Polymeric Solutions, Alison E. Patteson, Arvind Gopinath, Mark Goulian, Paulo E. Arratia
Physics - All Scholarship
Run-and-tumble motility is widely used by swimming microorganisms including numerous prokaryotic and eukaryotic organisms. Here, we experimentally investigate the run-and-tumble dynamics of the bacterium E. coli in polymeric solutions. We find that even small amounts of polymer in solution can drastically change E. colidynamics: cells tumble less and their velocity increases, leading to an enhancement in cell translational diffusion and a sharp decline in rotational diffusion. We show that suppression of tumbling is due to fluid viscosity while the enhancement in swimming speed is mainly due to fluid elasticity. Visualization of single fluorescently labeled DNA polymers reveals that the …
Electron And Hole Drift Mobility Measurements On Thin Film Cdte Solar Cells, Qi Long, Steluta A. Dinca, Eric A. Schiff, Ming Yu, Jeremy Theil
Electron And Hole Drift Mobility Measurements On Thin Film Cdte Solar Cells, Qi Long, Steluta A. Dinca, Eric A. Schiff, Ming Yu, Jeremy Theil
Physics - All Scholarship
We report electron and hole drift mobilities in thin film polycrystalline CdTe solar cells based on photocarrier time-of-flight measurements. For a deposition process similar to that used for high-efficiency cells, the electron drift mobilities are in the range of 10–100 cm2/Vs, and holes are in the range of 1–10 cm2/Vs. The electron drift mobilities are about a thousand times smaller than those measured in single crystal CdTe with time-of-flight; the hole mobilities are about ten times smaller. Cells were examined before and after a vapor phase treatment with CdCl2; treatment had little effect on …
Coalescence Of Bubbles And Drops In An Outer Fluid, Joseph Paulsen, Remi Carmigniani, Anerudh Kannan, Justin C. Burton
Coalescence Of Bubbles And Drops In An Outer Fluid, Joseph Paulsen, Remi Carmigniani, Anerudh Kannan, Justin C. Burton
Physics - All Scholarship
When two liquid drops touch, a microscopic connecting liquid bridge forms and rapidly grows as the two drops merge into one. Whereas coalescence has been thoroughly studied when drops coalesce in vacuum or air, many important situations involve coalescence in a dense surrounding fluid, such as oil coalescence in brine. Here we study the merging of gas bubbles and liquid drops in an external fluid. Our data indicate that the flows occur over much larger length scales in the outer fluid than inside the drops themselves. Thus, we find that the asymptotic early regime is always dominated by the viscosity …
Multiple Transient Memories In Experiments On Sheared Non-Brownian Suspensions, Joseph Paulsen, Nathan C. Keim, Sidney R. Nagel
Multiple Transient Memories In Experiments On Sheared Non-Brownian Suspensions, Joseph Paulsen, Nathan C. Keim, Sidney R. Nagel
Physics - All Scholarship
A system with multiple transient memories can remember a set of inputs but subsequently forgets almost all of them, even as they are continually applied. If noise is added, the system can store all memories indefinitely. The phenomenon has recently been predicted for cyclically sheared non-Brownian suspensions. Here we present experiments on such suspensions, finding behavior consistent with multiple transient memories and showing how memories can be stabilized by noise.
Structure And Dynamics Of Self-Assembling Colloidal Monolayers In Oscillating Magnetic Fields, Alison E. Patteson (Koser), Nathan C. Keim, Paulo E. Arratia
Structure And Dynamics Of Self-Assembling Colloidal Monolayers In Oscillating Magnetic Fields, Alison E. Patteson (Koser), Nathan C. Keim, Paulo E. Arratia
Physics - All Scholarship
Many fascinating phenomena such as large-scale collective flows, enhanced fluid mixing, and pattern formation have been observed in so-called active fluids, which are composed of particles that can absorb energy and dissipate it into the fluid medium. For active particles immersed in liquids, fluid-mediated viscous stresses can play an important role on the emergence of collective behavior. Here, we experimentally investigate their role in the dynamics of self-assembling magnetically driven colloidal particles which can rapidly form organized hexagonal structures. We find that viscous stresses reduce hexagonal ordering, generate smaller clusters, and significantly decrease the rate of cluster formation, all while …
Measuring Material Relaxation And Creep Recovery In A Microfluidic Device, Alison E. Patteson (Koser), Lichao Pan, Nathan C. Keim, Paulo E. Arratia
Measuring Material Relaxation And Creep Recovery In A Microfluidic Device, Alison E. Patteson (Koser), Lichao Pan, Nathan C. Keim, Paulo E. Arratia
Physics - All Scholarship
We present a novel method of testing creep recovery in a microfluidic device. This method allows for the measurement of relaxation time of fluids at low strain. After applying a steady pressure-driven flow along a microchannel, the pressure is released and the fluid is allowed to relax and come to rest. Local strains are observed via the time-dependent velocity profiles and are fit to a general viscoelastic model to obtain the fluids' relaxation times. The use of polymeric solutions of various molecular weights allows for the observation of time scales for strains ranging from 0.01 to 10. Results are consistent …
Multiple Transient Memories In Sheared Suspensions: Robustness, Structure, And Routes To Plasticity, Nathan C. Keim, Joseph D. Paulsen, Sidney R. Nagel
Multiple Transient Memories In Sheared Suspensions: Robustness, Structure, And Routes To Plasticity, Nathan C. Keim, Joseph D. Paulsen, Sidney R. Nagel
Physics - All Scholarship
Multiple transient memories, originally discovered in charge-density-wave conductors, are a remarkable and initially counterintuitive example of how a system can store information about its driving. In this class of memories, a system can learn multiple driving inputs, nearly all of which are eventually forgotten despite their continual input. If sufficient noise is present, the system regains plasticity so that it can continue to learn new memories indefinitely. Recently, Keim and Nagel [Phys. Rev. Lett. 107, 010603 (2011)] showed how multiple transient memories could be generalized to a generic driven disordered system with noise, giving as an example simulations of a …
Approach And Coalescence Of Liquid Drops In Air, Joseph Paulsen
Approach And Coalescence Of Liquid Drops In Air, Joseph Paulsen
Physics - All Scholarship
The coalescence of liquid drops has conventionally been thought to have just two regimes when the drops are brought together slowly in vacuum or air: a viscous regime corresponding to the Stokes-flow limit and a later inertially dominated regime. Recent work found that the Stokes-flow limit cannot be reached in the early moments of coalescence, because the inertia of the drops cannot be neglected then. Instead, the drops are described by an "inertially limited viscous" regime, where surface tension, inertia, and viscous forces all balance. The dynamics continue in this regime until either viscosity or inertia dominate on their own. …
Electron Drift-Mobility Measurements In Polycrystalline Cuin1-Xgaxse2 Solar Cells, Steluta A. Dinca, Eric A. Schiff, William N. Shafarman, Brian Egaas, Rommel Noufi, David L. Young
Electron Drift-Mobility Measurements In Polycrystalline Cuin1-Xgaxse2 Solar Cells, Steluta A. Dinca, Eric A. Schiff, William N. Shafarman, Brian Egaas, Rommel Noufi, David L. Young
Physics - All Scholarship
We report photocarrier time-of-flight measurements of electron drift mobilities for the p-type CuIn1-xGaxSe2 films incorporated in solar cells. The electron mobilities range from 0.02 to 0.05 cm^2/Vs and are weakly temperature-dependent from 100–300 K. These values are lower than the range of electron Hall mobilities (2-1100 cm2/Vs) reported for n-type polycrystalline thin films and single crystals. We propose that the electron drift mobilities are properties of disorder-induced mobility edges and discuss how this disorder could increase cell efficiencies.
The Inexorable Resistance Of Inertia Determines The Initial Regime Of Drop Coalescence, Joseph Paulsen, Justin C. Burton, Sidney R. Nagel, Santosh Appathurai, Michael T. Harris, Osman A. Basaran
The Inexorable Resistance Of Inertia Determines The Initial Regime Of Drop Coalescence, Joseph Paulsen, Justin C. Burton, Sidney R. Nagel, Santosh Appathurai, Michael T. Harris, Osman A. Basaran
Physics - All Scholarship
Drop coalescence is central to diverse processes involving dispersions of drops in industrial, engineering, and scientific realms. During coalescence, two drops first touch and then merge as the liquid neck connecting them grows from initially microscopic scales to a size comparable to the drop diameters. The curvature of the interface is infinite at the point where the drops first make contact, and the flows that ensue as the two drops coalesce are intimately coupled to this singularity in the dynamics. Conventionally, this process has been thought to have just two dynamical regimes: a viscous and an inertial regime with a …
Are Three Flavors Special?, Joseph Schechter, Amir H. Fariborz, Renata Jora, M. Naeem Shahid
Are Three Flavors Special?, Joseph Schechter, Amir H. Fariborz, Renata Jora, M. Naeem Shahid
Physics - All Scholarship
It has become clearer recently that the regular pattern of three flavor nonets describing the low spin meson multiplets seems to require some modification for the case of the spin 0 scalar mesons. One picture which has had some success, treats the scalars in a chiral Lagrangian framework and considers them to populate two nonets. These are, in turn, taken to result from the mixing of two "bare" nonets, one of which is of quark- antiquark type and the other of two quark- two antiquark type. Here we show that such a mixing is, before chiral symmetry breaking terms are …
De Sitter Gravity From Lattice Gauge Theory, Simon Catterall, Daniel Ferrante, Arwen Nicholson
De Sitter Gravity From Lattice Gauge Theory, Simon Catterall, Daniel Ferrante, Arwen Nicholson
Physics - All Scholarship
We investigate a lattice model for Euclidean quantum gravity based on discretization of the Palatini formulation of General Relativity. Using Monte Carlo simulation we show that while a naive approach fails to lead to a vacuum state consistent with the emergence of classical spacetime, this problem may be evaded if the lattice action is supplemented by an appropriate counter term. In this new model we find regions of the parameter space which admit a ground state which can be interpreted as (Euclidean) de Sitter space.
Thermodynamic Limit To Photonic-Plasmonic Light-Trapping In Thin Films On Metals, Eric A. Schiff
Thermodynamic Limit To Photonic-Plasmonic Light-Trapping In Thin Films On Metals, Eric A. Schiff
Physics - All Scholarship
We calculate the maximum optical absorptance enhancements in thin semiconductor films on metals due to structures that diffuse light and couple it to surface plasmon polaritons. The calculations can be used to estimate plasmonic effects on light-trapping in solar cells. The calculations are based on the statistical distribution of energy in the electromagnetic modes of the structure, which include surface plasmon polariton modes at the metal interface as well as the trapped waveguide modes in the film. The enhancement has the form 4n2+nλ/h (n – film refractive index, λ – optical wavelength, h …
A Measurement Of The Semileptonic Branching Fraction Of The B_S Meson, Duncan Brown, J. P. Lees
A Measurement Of The Semileptonic Branching Fraction Of The B_S Meson, Duncan Brown, J. P. Lees
Physics - All Scholarship
We report a measurement of the inclusive semileptonic branching fraction of the B_s meson using data collected with the BaBar detector in the center-of-mass (CM) energy region above the Upsilon(4S) resonance. We use the inclusive yield of phi mesons and the phi yield in association with a high-momentum lepton to perform a simultaneous measurement of the semileptonic branching fraction and the production rate of B_s mesons relative to all B mesons as a function of CM energy. The inclusive semileptonic branching fraction of the B_s meson is determined to be B(B_s to l nu X)=9.5 (+2.5/-2.0)(stat)(+1.1/-1.9)(syst)%, where l indicates the …
The Importance Of Slow-Roll Corrections During Multi-Field Inflation, Scott Watson, Anastasios Avgoustidis, Sera Cremonini, Anne-Christine Davis
The Importance Of Slow-Roll Corrections During Multi-Field Inflation, Scott Watson, Anastasios Avgoustidis, Sera Cremonini, Anne-Christine Davis
Physics - All Scholarship
We re-examine the importance of slow-roll corrections during the evolution of cosmological perturbations in models of multi-field inflation. We find that in many instances the presence of light degrees of freedom leads to situations in which next to leading order slow-roll corrections become significant. Examples where we expect such corrections to be crucial include models in which modes exit the Hubble radius while the inflationary trajectory undergoes an abrupt turn in field space, or during a phase transition. We illustrate this with two examples -- hybrid inflation and double quadratic inflation. Utilizing both analytic estimates and full numerical results, we …
Generic Phases Of Cross-Linked Active Gels: Relaxation, Oscillation And Contractility, Shiladitya Banerjee, Tanniemola B. Liverpool, M. C. Marchetti
Generic Phases Of Cross-Linked Active Gels: Relaxation, Oscillation And Contractility, Shiladitya Banerjee, Tanniemola B. Liverpool, M. C. Marchetti
Physics - All Scholarship
We study analytically and numerically a generic continuum model of an isotropic active solid with internal stresses generated by non-equilibrium `active' mechano-chemical reactions. Our analysis shows that the gel can be tuned through three classes of dynamical states by increasing motor activity: a constant unstrained state of homogeneous density, a state where the local density exhibits sustained oscillations, and a steady-state which is spontaneously contracted, with a uniform mean density.
Systematic Errors Of The Mcrg Method, Simon Catterall, Luigi Del Debbio, Joel Giedt, Liam Keegan
Systematic Errors Of The Mcrg Method, Simon Catterall, Luigi Del Debbio, Joel Giedt, Liam Keegan
Physics - All Scholarship
We present a Monte Carlo Renormalisation Group (MCRG) study of the SU(2) gauge theory with two Dirac fermions in the adjoint representation. Using the two-lattice matching technique we measure the running of the coupling and the anomalous mass dimension. We find slow running of the coupling, compatible with an infrared fixed point. Assuming this running is negligible we find a vanishing anomalous dimension, gamma=-0.03(13), however without this assumption our uncertainty in the running of the coupling leads to a much larger range of allowed values, -0.6 < gamma < 0.6. We discuss the systematic errors affecting the current analysis and possible improvements.
Three-Dimensional Folding Of The Triangular Lattice, Mark Bowick, P Di Francesco, Oliver Golinelli, Emmanuel Guitter
Three-Dimensional Folding Of The Triangular Lattice, Mark Bowick, P Di Francesco, Oliver Golinelli, Emmanuel Guitter
Physics - All Scholarship
We study the folding of the regular triangular lattice in three dimensional embedding space, a model for the crumpling of polymerised membranes. We consider a discrete model, where folds are either planar or form the angles of a regular octahedron. These "octahedral" folding rules correspond simply to a discretisation of the 3d embedding space as a Face Centred Cubic lattice. The model is shown to be equivalent to a 96--vertex model on the triangular lattice. The folding entropy per triangle ${\rm ln} q_{3d}$ is evaluated numerically to be $q_{3d}=1.43(1)$. Various exact bounds on $q_{3d}$ are derived.
Search For The Lepton Number Violating Decays B+ → Π- Μ+Μ+ And B+→ K-Μ+ Μ+, Raymond Mountain, Marina Artuso, S. Blusk, Alessandra Borgia
Search For The Lepton Number Violating Decays B+ → Π- Μ+Μ+ And B+→ K-Μ+ Μ+, Raymond Mountain, Marina Artuso, S. Blusk, Alessandra Borgia
Physics - All Scholarship
A search is performed for the lepton number violating decay B^{+}\rightarrow h^- \mu^+ \mu^+, where h^- represents a K^- or a \pi^-, using data from the LHCb detector corresponding to an integrated luminosity of 36pb^{-1}. The decay is forbidden in the Standard Model but allowed in models with a Majorana neutrino. No signal is observed in either channel and limits of B(B^{+} \rightarrow K^- \mu^+ \mu^+) < 5.4\times 10^{-8} and B(B^{+} \rightarrow \pi^- \mu^+ \mu^+) < 5.8\times 10^{-8} are set at the 95% confidence level. These improve the previous best limits by factors of 40 and 30, respectively.
Search For Lepton-Number Violating Processes In B+ -> H- L+ L+ Decays, Raymond Mountain, Marina Artuso, S. Blusk, Alessandra Borgia
Search For Lepton-Number Violating Processes In B+ -> H- L+ L+ Decays, Raymond Mountain, Marina Artuso, S. Blusk, Alessandra Borgia
Physics - All Scholarship
A search is performed for the lepton number violating decay B^{+}\rightarrow h^- \mu^+ \mu^+, where h^- represents a K^- or a \pi^-, using data from the LHCb detector corresponding to an integrated luminosity of 36pb^{-1}. The decay is forbidden in the Standard Model but allowed in models with a Majorana neutrino. No signal is observed in either channel and limits of B(B^{+} \rightarrow K^- \mu^+ \mu^+) < 5.4\times 10^{-8} and B(B^{+} \rightarrow \pi^- \mu^+ \mu^+) < 5.8\times 10^{-8} are set at the 95% confidence level. These improve the previous best limits by factors of 40 and 30, respectively.
All-Sky Search For Periodic Gravitational Waves In The Full S5 Ligo Data, Duncan Brown, J. Abadie, Stefan Ballmer, Collin Capano, P. Couvares
All-Sky Search For Periodic Gravitational Waves In The Full S5 Ligo Data, Duncan Brown, J. Abadie, Stefan Ballmer, Collin Capano, P. Couvares
Physics - All Scholarship
We report on an all-sky search for periodic gravitational waves in the frequency band 50-800 Hz and with the frequency time derivative in the range of 0 through -6e-9 Hz/s. Such a signal could be produced by a nearby spinning and slightly non-axisymmetric isolated neutron star in our galaxy. After recent improvements in the search program that yielded a 10x increase in computational efficiency, we have searched in two years of data collected during LIGO's fifth science run and have obtained the most sensitive all-sky upper limits on gravitational wave strain to date. Near 150 Hz our upper limit on …
Measurements Of The Branching Fractions For B(S) → D(S)Πππ And Λb0 → Λc+Πππ, Raymond Mountain, Marina Artuso, S. Blusk, Alessandra Borgia
Measurements Of The Branching Fractions For B(S) → D(S)Πππ And Λb0 → Λc+Πππ, Raymond Mountain, Marina Artuso, S. Blusk, Alessandra Borgia
Physics - All Scholarship
Branching fractions of the decays H_b\to H_c\pi^-\pi^+\pi^- relative to H_b\to H_c\pi^- are presented, where H_b (H_c) represents B^0-bar(D^+), B^- (D^0), B_s^0-bar (D_s^+) and \Lambda_b^0 (\Lambda_c^+). The measurements are performed with the LHCb detector using 35{\rm pb^{-1}} of data collected at \sqrt{s}=7 TeV. The ratios of branching fractions are measured to be B(B^0-bar -> D^+\pi^-\pi^+\pi^-)/ B(B^0-bar -> D^+\pi^-) = 2.38\pm0.11\pm0.21 B(B^- -> D^0\pi^-\pi^+\pi^-) / B(B^- -> D^0\pi^-) = 1.27\pm0.06\pm0.11 B(B_s^0-bar -> D_s^+\pi^-\pi^+\pi^-) / B(B_s^0-bar -> D_s^+\pi^-) = 2.01\pm0.37\pm0.20 B(\Lambda_b^0->\Lambda_c^+\pi^-\pi^+\pi^-) / B(\Lambda_b^0 -> \Lambda_c^+\pi^-) = 1.43\pm0.16\pm0.13. We also report measurements of partial decay rates of these decays to excited charm hadrons. …