Physics Commons^™

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 …

Characterization Of Enhanced Interferometric Gravitational Wave Detectors And Studies Of Numeric Simulations For Compact-Binary Coalescences, Larne Pekowsky

Physics - Dissertations

Gravitational waves are a consequence of the general theory of relativity. Direct detection of such waves will provide a wealth of information about physics, astronomy, and cosmology. A worldwide effort is currently underway to make the first direct detection of gravitational waves. The global network of detectors includes the Laser Interferometer Gravitational-wave Observatory (LIGO), which recently completed its sixth science run.

A particularly promising source of gravitational waves is a binary system consisting of two neutron stars and/or black holes. As the objects orbit each other they emit gravitational radiation, lose energy, and spiral inwards. This produces a characteristic ``chirp'' …

Searching For Gravitational Waves From Compact Binary Coalescence Using Ligo And Virgo Data, Collin Capano

Physics - Dissertations

This thesis describes current efforts to search for gravitational waves from compact binary coalescences (CBCs) by the LIGO Scientific Collaboration (LSC) and the Virgo Collaboration. We briefly review the physics of gravitational-wave emission and detection, describing how gravitational waves are emitted from "inspiraling" compact stellar mass objects and how the LSC and Virgo try to detect them using interferometers. Next we review the data-analysis principles used to search for potential signals in the detectors' noise. These principles are employed by ``ihope," which is the data-analysis pipeline used to search for CBCs. We describe each step in this pipeline and discuss …

Interacting Stochastic Processes: From Viciousness To Caging To Force Chains, Shiliyang Xu

Physics - Dissertations

This thesis documents a quest to develop and study several novel interacting stochastic processes. As for the first example, we generalize a system of vicious random walkers in which the only interaction between any two random walkers is that when they intersect, both walkers are annihilated. We define a system of N vicious accelerating walkers with each walker undergoing random acceleration and compute the survival probability distribution for this system. We also define and study a system of N vicious Levy flights in which any two Levy flights crossing one another annihilate each other. The average mean-squared displacement of a …

The Design And Construction Of A Green Laser And Fabry-Perot Cavity System For Jefferson Lab's Hall A Compton Polarimeter, Abdurahim Rakhman

Physics - Dissertations

A high finesse Fabry-Perot cavity with a frequency doubled green laser (CW, 532 nm) have been built and installed in Hall A of Jefferson Lab for high precision Compton polarimetry project in spring of 2010. It provides a high intensity circularly polarized photon target for measuring the polarization of electron beam with energies from 1.0 GeV to 11.0 GeV in a nondestructive manner. The IR beam (CW, 1064 nm) from a Ytterbium doped fiber laser amplifier seeded by a Nd:YAG narrow linewidth NPRO laser is frequency doubled in by a single-pass Periodically Poled Lithium Niobate (PPMgLN) crystal. The maximum achieved …

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

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

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

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

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

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

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

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

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

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

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. …

Measurements Of The Branching Fractions For B_(S) -> D_(S)Πππ And Λ_B^0 -> Λ_C^+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. …

Amplitude Analyses Of The Decays Χc1 →Ηπ+Π- And Χc1→Η'Π+Π-, Raymond Mountain, Marina Artuso, S. Blusk, T. Skwarnicki

Physics - All Scholarship

Using a data sample of 2.59 x 10^7 psi(2S) decays obtained with the CLEO-c detector, we perform amplitude analyses of the complementary decay chains chi_c1 -> eta pi+ pi- and chi_c1 -> eta' pi+ pi-. We find evidence for a P-wave eta' pi scattering amplitude, which, if interpreted as a resonance, would have exotic J^PC = 1^-+ and parameters consistent with the pi_1(1600) state reported in other production mechanisms. We also make the first observation of the decay a_0(980) -> eta' pi and measure the ratio of branching fractions B(a_0(980) -> eta' pi)/B(a_0(980) -> eta pi) = 0.064 +- 0.014 …

Amplitude Analyses Of The Decays Chi_C1 -> Eta Pi+ Pi- And Chi_C1 -> Eta' Pi+ Pi-, Raymond Mountain, Marina Artuso, S. Blusk, T. Skwarnicki

Physics - All Scholarship

Using a data sample of 2.59 x 10^7 psi(2S) decays obtained with the CLEO-c detector, we perform amplitude analyses of the complementary decay chains chi_c1 -> eta pi+ pi- and chi_c1 -> eta' pi+ pi-. We find evidence for a P-wave eta' pi scattering amplitude, which, if interpreted as a resonance, would have exotic J^PC = 1^-+ and parameters consistent with the pi_1(1600) state reported in other production mechanisms. We also make the first observation of the decay a_0(980) -> eta' pi and measure the ratio of branching fractions B(a_0(980) -> eta' pi)/B(a_0(980) -> eta pi) = 0.064 +- 0.014 …

Implementation And Testing Of The First Prompt Search For Electromagnetic Counterparts To Gravitational Wave Transients, Duncan Brown, J. Abadie, Stefan Ballmer, Collin Capano, P. Couvares

Physics - All Scholarship

Aims. A transient astrophysical event observed in both gravitational wave (GW) and electromagnetic (EM) channels would yield rich scientific rewards. A first program initiating EM follow-ups to possible transient GW events has been developed and exercised by the LIGO and Virgo community in association with several partners. In this paper, we describe and evaluate the methods used to promptly identify and localize GW event candidates and to request images of targeted sky locations. Methods. During two observing periods (Dec 17 2009 to Jan 8 2010 and Sep 2 to Oct 20 2010), a low-latency analysis pipeline was used to identify …

The Baryon-Dark Matter Ratio Via Moduli Decay After Affleck-Dine Baryogenesis, Scott Watson, Gordon Kane, Jing Shao, Hai-Bo Yu

Physics - All Scholarship

Low-scale supersymmetry breaking in string motivated theories implies the presence of O(100) TeV scale moduli, which generically lead to a significant modification of the history of the universe prior to Big Bang Nucleosynthesis. Such an approach implies a non-thermal origin for dark matter resulting from scalar decay, where the lightest supersymmetric particle can account for the observed dark matter relic density. We study the further effect of the decay on the baryon asymmetry of the universe, and find that this can satisfactorily address the problem of the over-production of the baryon asymmetry by the Affleck-Dine mechanism in the MSSM. Remarkably, …

Observation Of J/Ψ Pair Production In Pp Collisions At √S=7 Tev, Raymond Mountain, Marina Artuso, S. Blusk, Alessandra Borgia

Physics - All Scholarship

The production of J/\psi pairs in proton-proton collisions at a centre-of-mass energy of 7 TeV has been observed using an integrated luminosity of 37.5 pb^{-1} collected with the LHCb detector. The production cross-section for pairs with both \jpsi in the rapidity range 2

Observation Of J/Ψ Pair Production In Pp Collisions At \Sqrt{S}=7 Tev, Raymond Mountain, Marina Artuso, S. Blusk, Alesandra Borgia

Physics - All Scholarship

The production of J/\psi pairs in proton-proton collisions at a centre-of-mass energy of 7 TeV has been observed using an integrated luminosity of 37.5 pb^{-1} collected with the LHCb detector. The production cross-section for pairs with both \jpsi in the rapidity range 2

Observation Of The H_C(1p) Using E^+E^- Collisions Above Ddbar Threshold, Raymond Mountain, Marina Artuso, S. Blusk, T. Skwarnicki

Physics - All Scholarship

Using 586pb^-1 of e^+e^- collision data at E_CM = 4170MeV, produced at the CESR collider and collected with the CLEO-c detector, we observe the process e^+e^- --> pi^+ pi^- h_c(1P). We measure its cross section to be 15.6+-2.3+-1.9+-3.0pb, where the third error is due to the external uncertainty on the branching fraction of psi(2S) --> pi^0 h_c(1P), which we use for normalization. We also find evidence for e^+e^- --> eta h_c(1P) at 4170MeV at the 3sigma level, and see hints of a rise in the e^+e^- --> pi^+ pi^- h_c(1P) cross section at 4260MeV.

Quantum Equivalence Principle Violations In Scalar-Tensor Theories, Christian Armendariz-Picon, Riccardo Penco

Physics - All Scholarship

We study the equivalence principle and its violations by quantum effects in scalar-tensor theories that admit a conformal frame in which matter only couples to the spacetime metric. These theories possess Ward identities that guarantee the validity of the weak equivalence principle to all orders in the matter coupling constants. These Ward identities originate from a broken Weyl symmetry under which the scalar field transforms by a shift, and from the symmetry required to couple a massless spin two particle to matter (diffeomorphism invariance). But the same identities also predict violations of the weak equivalence principle relatively suppressed by at …

Observation Of The Hc(1p) Using E+E- Collisions Above Dd Threshold, Raymond Mountain, Marina Artuso, S. Blusk, T. Skwarnicki

Physics - All Scholarship

Using 586pb^-1 of e^+e^- collision data at E_CM = 4170MeV, produced at the CESR collider and collected with the CLEO-c detector, we observe the process e^+e^- --> pi^+ pi^- h_c(1P). We measure its cross section to be 15.6+-2.3+-1.9+-3.0pb, where the third error is due to the external uncertainty on the branching fraction of psi(2S) --> pi^0 h_c(1P), which we use for normalization. We also find evidence for e^+e^- --> eta h_c(1P) at 4170MeV at the 3sigma level, and see hints of a rise in the e^+e^- --> pi^+ pi^- h_c(1P) cross section at 4260MeV.

Substrate Rigidity Deforms And Polarizes Active Gels, Shiladitya Banerjee, M. C. Marchetti

Physics - All Scholarship

We present a continuum model of the coupling between cells and substrate that accounts for some of the observed substrate-stiffness dependence of cell properties. The cell is modeled as an elastic active gel, adapting recently developed continuum theories of active viscoelastic fluids. The coupling to the substrate enters as a boundary condition that relates the cell's deformation field to local stress gradients. In the presence of activity, the coupling to the substrate yields spatially inhomogeneous contractile stresses and deformations in the cell and can enhance polarization, breaking the cell's front-rear symmetry.

Branching Fractions For Y(3s) -> Pi^0 H_B And Psi(2s) -> Pi^0 H_C, Raymond Mountain, Marina Artuso, S. Blusk, T. Skwarnicki

Physics - All Scholarship

Using e^+e^- collision data corresponding to 5.88M Y(3S) [25.9M psi(2S)] decays and acquired by the CLEO III [CLEO-c] detectors operating at CESR, we study the single-pion transitions from Y(3S) [psi(2S)] to the respective spin-singlet states h_{b[c]}. Utilizing only the momentum of suitably selected transition-pi^0 candidates, we obtain the upper limit B(Y(3S) -> pi^0 h_b) < 1.2\times 10^{-3} at 90% confidence level, and measure B(psi(2S) -> pi^0 h_c) = (9.0+-1.5+-1.3)\times 10^{-4}. Signal sensitivities are enhanced by excluding very asymmetric pi^0 -> gamma gamma candidates.

Branching Fractions For ϒ(3s)→ Π0hb And Ψ(2s) →Π0hc, Raymond Mountain, Marina Artuso, S. Blusk, T. Skwarnicki

Physics - All Scholarship

Using e^+e^- collision data corresponding to 5.88M Y(3S) [25.9M psi(2S)] decays and acquired by the CLEO III [CLEO-c] detectors operating at CESR, we study the single-pion transitions from Y(3S) [psi(2S)] to the respective spin-singlet states h_{b[c]}. Utilizing only the momentum of suitably selected transition-pi^0 candidates, we obtain the upper limit B(Y(3S) -> pi^0 h_b) < 1.2\times 10^{-3} at 90% confidence level, and measure B(psi(2S) -> pi^0 h_c) = (9.0+-1.5+-1.3)\times 10^{-4}. Signal sensitivities are enhanced by excluding very asymmetric pi^0 -> gamma gamma candidates.

Plasmonic Nanogels With Robustly Tunable Optical Properties, Tao Cong, Satvik N. Wani, Georo Zhou, Elia Baszczuk, Radhakrishna Sureshkumar

Biomedical and Chemical Engineering - All Scholarship

Low viscosity fluids with tunable optical properties can be processed to manufacture thin film and interfaces for molecular detection, light trapping in photovoltaics and reconfigurable optofluidic devices. In this work, self-assembly in wormlike micelle solutions is used to uniformly distribute various metallic nanoparticles to produce stable suspensions with localized, multiple wavelength or broad-band optical properties. Their spectral response can be robustly modified by varying the species, concentration, size and/or shape of the nanoparticles. Structure, rheology and optical properties of these plasmonic nanogels as well as their potential applications to efficient photovoltaics design are discussed.