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Full-Text Articles in Physical Sciences and Mathematics
Quantum-Monte-Carlo Calculations For Bosons In A Two-Dimensional Harmonic Trap, Stefan Heinrichs, William J. Mullin
Quantum-Monte-Carlo Calculations For Bosons In A Two-Dimensional Harmonic Trap, Stefan Heinrichs, William J. Mullin
Physics Department Faculty Publication Series
Path-Integral-Monte-Carlo simulation has been used to calculate the properties of a two-dimensional (2D) interacting Bose system. The bosons interact with hard-core potentials and are confined to a harmonic trap. Results for the density profiles, the condensate fraction, and the superfluid density are presented. By comparing with the ideal gas we easily observe the effects of finite size and the depletion of the condensate because of interactions. The system is known to have no phase transition to a Bose-Einstein condensation in 2D, but the finite system shows that a significant fraction of the particles are in the lowest state at low …
Brownian Motion And Polymer Statistics On Certain Curved Manifolds, Radu P. Mondescu, M. Muthukumar
Brownian Motion And Polymer Statistics On Certain Curved Manifolds, Radu P. Mondescu, M. Muthukumar
Physics Department Faculty Publication Series
No abstract provided.
Can Nearby Resonances Enhance D-0-(D)Over-Bar(0) Mixing?, E Golowich, Aa Petrov
Can Nearby Resonances Enhance D-0-(D)Over-Bar(0) Mixing?, E Golowich, Aa Petrov
Physics Department Faculty Publication Series
We study the contributions of resonances to mixing. Both and hybrid states are considered. Assuming reasonable values for the resonance parameters, we find relatively sizeable individual contributions to both ΔmD and ΔΓD. We derive a variant of the GIM cancellation mechanism for the resonance amplitudes and show that broken SU(3) can allow for appreciable residual effects. Additional input from meson spectroscopy and lattice gauge simulations will be needed to improve the accuracy of these predictions.
The Dmo Sum Rule Revisited, E Golowich, J Kambor
The Dmo Sum Rule Revisited, E Golowich, J Kambor
Physics Department Faculty Publication Series
We reconsider the DMO sum rule in light of our recent two-loop calculations of isospin and hypercharge vector and axialvector current propagators in chiral perturbation theory. A modified derivation valid to second order in the light quark masses is presented, and a phenomenological analysis yields determination of a combination of finite counterterms occurring in the p4 and p6 chiral lagrangians. Suggestions are given for further study.
Exact, Complete, And Universal Continuous-Time Worldline Monte Carlo Approach To The Statistics Of Discrete Quantum Systems, Nikolai Prokof'ev, Boris Svistunov, Tupitsyn
Exact, Complete, And Universal Continuous-Time Worldline Monte Carlo Approach To The Statistics Of Discrete Quantum Systems, Nikolai Prokof'ev, Boris Svistunov, Tupitsyn
Physics Department Faculty Publication Series
We show how the worldline quantum Monte Carlo procedure, which usually relies on an artificial time discretization, can be formulated directly in continuous time, rendering the scheme exact. For an arbitrary system with discrete Hilbert space, none of the configuration update procedures contain small parameters. We find that the most effective update strategy involves the motion of worldline discontinuities (both in space and time), i.e., the evaluation of the Green’s function. Being based on local updates only, our method nevertheless allows one to work with the grand canonical ensemble and nonzero winding numbers, and to calculate any dynamical correlation function …
U Duality, D-Branes, And Black Hole Emission Rates: Agreements And Disagreements, F Dowker, David Kastor, Jennie Traschen
U Duality, D-Branes, And Black Hole Emission Rates: Agreements And Disagreements, F Dowker, David Kastor, Jennie Traschen
Physics Department Faculty Publication Series
An expression for the spacetime absorption coefficient of a scalar field in a five-dimensional, near-extremal black hole background is derived, which has the same form as that presented by Maldacena and Strominger, but is valid over a larger, U-duality invariant region of parameter space and in general disagrees with the corresponding D-brane result. We develop an argument, based on D-brane thermodynamics, which specifies the range of parameters over which agreement should be expected. For neutral emission, the spacetime and D-brane results agree over this range. However, for charged emission, we find disagreement in the “fat black hole” regime, in which …
Non-Extreme Calabi-Yau Black Holes, David Kastor, K.Z Win
Non-Extreme Calabi-Yau Black Holes, David Kastor, K.Z Win
Physics Department Faculty Publication Series
Non-extreme black hole solutions of four dimensional, N = 2 supergravity theories with Calabi-Yau prepotentials are presented, which generalize certain known double-extreme and extreme solutions. The boost parameters characterizing the nonextreme solutions must satisfy certain constraints, which effectively limit the functional independence of the moduli scalars. A necessary condition for being able to take certain boost parameters independent is found to be block diagonality of the gauge coupling matrix. We present a number of examples aimed at developing an understanding of this situation and speculate about the existence of more general solutions.
Anthropic Considerations In Multiple-Domain Theories And The Scale Of Electroweak Symmetry Breaking, V Agrawal, Sm Barr, Jf Donoghue, D Seckel
Anthropic Considerations In Multiple-Domain Theories And The Scale Of Electroweak Symmetry Breaking, V Agrawal, Sm Barr, Jf Donoghue, D Seckel
Physics Department Faculty Publication Series
One of the puzzles of the Standard Model is why the mass parameter which determines the scale of the Weak interactions is closer to the scale of Quantum Chromodymanics (QCD) than to the Grand Unification or Planck scales. We discuss a novel approach to this problem which is possible in theories in which different regions of the universe can have different values of the the physical parameters. In such a situation, we would naturally find ourselves in a region which has parameters favorable for life. We explore the whole range of possible values of the mass parameter in the Higgs …
Low Energy Compton Scattering And Nucleon Structure, Br Holstein
Low Energy Compton Scattering And Nucleon Structure, Br Holstein
Physics Department Faculty Publication Series
The low energy virtual Compton scattering process eN\rightarrow e'N\gamma offers a new and potentially high resolution window on nucleon structure via measurement of so-called generalized polarizabilities (GPs). We present calculations of GPs within heavy baryon chiral perturbation theory and discuss present experimental efforts.
A Study Of Bose-Einstein Condensation In A Two-Dimensional Trapped Gas, Wj Mullin
A Study Of Bose-Einstein Condensation In A Two-Dimensional Trapped Gas, Wj Mullin
Physics Department Faculty Publication Series
We examine the possibility of Bose-Einstein condensation (BEC) in two-dimensional (2D) system of interacting particles in a trap. We use a self-consistent mean-field theory of Bose particles interacting by a contact interaction in the Popov and WKB approximations. The equations show that the normal state has a phase transition at some critical temperature T c but below T c the Bose-Einstein condensed state is not a consistent solution of the equations in the thermodynamic limit. This result agrees with a theorem recently discussed by the author that shows that a BEC state is impossible for an interacting gas in a …
Chiral Predictions For K-L ->Pi(0)Gamma Mu(+)Mu(-), Jf Donoghue, F Gabbiani
Chiral Predictions For K-L ->Pi(0)Gamma Mu(+)Mu(-), Jf Donoghue, F Gabbiani
Physics Department Faculty Publication Series
We have previously analysed the chiral predictions for the decay KL ! 0 e+e− and discussed how experimental measurements of this process can help our understanding of chiral theories and of CP tests. Motivated by the possibility that the analogous muonic process may soon be measurable, we extend this calculation to the decay KL ! 0 μ+μ−. Branching ratios and differential branching ratios are calculated and presented. Measurements of these will help shed some light on the puzzles in our understanding of the chiral loop effects which were raised by the rate for KL ! 0 .
Generalized Polarizabilities And The Chiral Structure Of The Nucleon, Tr Hemmert, Br Holstein, G Knochlein, S Scherer
Generalized Polarizabilities And The Chiral Structure Of The Nucleon, Tr Hemmert, Br Holstein, G Knochlein, S Scherer
Physics Department Faculty Publication Series
We discuss the virtual Compton scattering reaction e−p → e−pγ at low energies. We present results for the generalized polarizabilities of the nucleon obtained in heavy baryon chiral perturbation theory at O(p3).
Chiral Anomaly And Eta-Eta ' Mixing, Ep Venugopal, Br Holstein
Chiral Anomaly And Eta-Eta ' Mixing, Ep Venugopal, Br Holstein
Physics Department Faculty Publication Series
We determine the η-η′ mixing angle via a procedure relatively independent of theoretical assumptions by simultaneously fitting η,η′ reactions involving the anomaly η,η′→γγ, π+π-γ. We extract reasonably precise renormalized values of the octet and singlet pseudoscalar decay constants F8, F0, as well as the mixing angle θ.
Heavy Baryon Chiral Perturbation Theory With Light Deltas, Tr Hemmert, Br Holstein, J Kambor
Heavy Baryon Chiral Perturbation Theory With Light Deltas, Tr Hemmert, Br Holstein, J Kambor
Physics Department Faculty Publication Series
We demonstrate how heavy mass methods, previously applied to chiral perturbation theory calculations involving the interactions of nucleons and pions, can be generalized to include interactions with the (1232) in a systematic formalism which we call the `small-scale expansion'.
Compton Scattering And The Spin Structure Of The Nucleon At Low Energies, Tr Hemmert, Br Holstein, J Kambor, G Knochlein
Compton Scattering And The Spin Structure Of The Nucleon At Low Energies, Tr Hemmert, Br Holstein, J Kambor, G Knochlein
Physics Department Faculty Publication Series
We analyze polarized Compton scattering which provides information on the spin-structure of the nucleon. For scattering processes with photon energies up to 100 MeV the spin-structure dependence can be encoded into four independent parameters—the so-called spin-polarizabilities γi, i=1,…,4, of the nucleon, which we calculate within the framework of the “small scale expansion” in SU(2) baryon chiral perturbation theory. Specific application is made to “forward” and “backward” spin-polarizabilities.
Search For Physics Beyond The Standard Model Via A Polarization-Asymmetry Correlation Experiment On In-107, B Vereecke, J Camps, N Severijns, J Deutsch, T Otto, J Govaerts, Ba Brown, B Holstein, R Kirchner, O Naviliat-Cuncic, R Prieels, Pa Quin, E Thomas, P De Moor, P Schuurmans, A Van Geert, L Vanneste
Search For Physics Beyond The Standard Model Via A Polarization-Asymmetry Correlation Experiment On In-107, B Vereecke, J Camps, N Severijns, J Deutsch, T Otto, J Govaerts, Ba Brown, B Holstein, R Kirchner, O Naviliat-Cuncic, R Prieels, Pa Quin, E Thomas, P De Moor, P Schuurmans, A Van Geert, L Vanneste
Physics Department Faculty Publication Series
We report on a new precision measurement of the longitudinal polarization of positrons emitted by polarized 107In nuclei. If interpreted in the framework of the manifest left-right symmetric model, preliminary results yield a lower limit of 303 GeV/c2 for the mass of a possible, predominantly right-handed W gauge boson.
Improved Treatment Of Loop Diagrams In Su(3) Baryon Chiral Perturbation Theory, Jf Donoghue, Br Holstein
Improved Treatment Of Loop Diagrams In Su(3) Baryon Chiral Perturbation Theory, Jf Donoghue, Br Holstein
Physics Department Faculty Publication Series
Baryon chiral perturbation theory as conventionally applied has a well-known problem with the SU(3) chiral expansion in that loop diagrams generate very large SU(3) breaking corrections and greatly upset the subsequent phenomenology. We argue that the problem comes from the portions of loop integrals corresponding to propagation at such short distances that the effective theory is not valid. One can reformulate the theory equally rigorously by regulating the loop integrals using a momentum-space cutoff which removes the spurious short-distance physics. We show that this reformulation improves the phenomenology for reasonable values of the cutoff.
Weight For Random Quark Masses, Jf Donoghue
Weight For Random Quark Masses, Jf Donoghue
Physics Department Faculty Publication Series
In theories in which the parameters of the low energy theory are not unique, perhaps having different values in different domains of the universe as is possible in some inflationary models, the fermion masses would be distributed with respect to some weight. In such a situation the specifics of the fermion masses do not have a unique explanation, yet the weight provides the visible remnant of the structure of the underlying theory. This paper introduces this concept of a weight for the distribution of masses and provides a quantitative estimate of it from the observed quarks and leptons. The weight …
Two-Loop Analysis Of Axial Vector Current Propagators In Chiral Perturbation Theory, E Golowich, J Kambor
Two-Loop Analysis Of Axial Vector Current Propagators In Chiral Perturbation Theory, E Golowich, J Kambor
Physics Department Faculty Publication Series
We perform a calculation of the isospin and hypercharge axial vector current propagators [ΔA3μν(q) and ΔA8μν(q)] to two loops in SU(3)×SU(3) chiral perturbation theory. A large number of O(p6) divergent counterterms are fixed, and complete two-loop renormalized expressions for the pion and eta masses and decay constants are obtained. The calculated isospin and hypercharge axial vector polarization functions are used as input in new chiral sum rules, valid to second order in the light quark masses. Some phenomenological implications of these sum rules are considered.
Nucleon Axial Matrix Elements, Br Holstein
Nucleon Axial Matrix Elements, Br Holstein
Physics Department Faculty Publication Series
Current issues associated with nucleon axial matrix elements are studied, including the Goldberger-Treiman discrepancy, the induced pseudoscalar, and SU(3) chiral perturbation theory.
Is Su(3) Chiral Perturbation Theory An Effective Field Theory?, Br Holstein
Is Su(3) Chiral Perturbation Theory An Effective Field Theory?, Br Holstein
Physics Department Faculty Publication Series
We argue that the difficulties associated with the convergence properties of conventional SU(3) chiral perturbation theory can be ameliorated by use of a cutoff, which suppresses the model-dependent short distance effects in such calculations.
Very Effective String Model?, David Kastor, Jennie Traschen
Very Effective String Model?, David Kastor, Jennie Traschen
Physics Department Faculty Publication Series
Additional evidence is presented for a recently proposed effective string model, conjectured to hold throughout the parameter space of the basic 5 dimensional, triply charged black holes, which includes the effects of brane excitations, as well as momentum modes. We compute the low energy spacetime absorption coefficient σ for the scattering of a triply charged scalar field in the near extremal case, and conjecture an exact form for σ. It is shown that this form of σ arises simply from the effective string model. This agreement encompasses both statistical factors coming from the Bose distributions of string excitations and a …