Faculty Publications and Research

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Now showing 1 - 20 of 193
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    $\text{CPT}$ Violation and Baryogenesis
    (Physics Letters B, 1997) Bertolami, O.; Colladay, Don; Kostelecký, V.A.; Potting, R.
    We examine the effects on baryogenesis of spontaneous $\text{CPT}$ violation in a string-based scenario. Under suitable circumstances, certain $\text{CPT}$-violating terms can produce a large baryon asymmetry at the grand-unified scale that reduces to the observed value via sphaleron or other dilution mechanisms.
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    Nuclear null tests for spacelike neutrinos
    (Physics Letters B, 1994) Chodos, Alan; Kostelecký, V.A.
    Recently, a type of null experiment for spacelike neutrinos has been proposed. We examine in detail a class of null tests involving nuclear beta decay or capture in atoms and ions. The most promising candidate systems are identified.
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    The neutrino as a tachyon
    (Physics Letters B, 1985) Chodos, Alan; Hauser, Avi I.; Kostelecký, V.A.
    We investigate the hypothesis that at least one of the known neutrinos travels faster than light. The current experimental situation is examined within this purview.
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    $\text{CPT}$ and strings
    (Nuclear Physics B) Kostelecký, V.A.; Potting, Robertus
    We define the string space-time symmetries $\text{C,P,T}$ and their products. The effects of nonlocal interactions and the infinite number of particle fields are incorporated using string field theory. At the dynamical level, $\text{C,P,T}$ and their products are preserved by the open bosonic string. Only the product $\text{CPT}$ is dynamically preserved by the superstring, although a modified action can be constructed to preserve $\text{C}$. We show that these discrete symmetries may be spontaneously broken in a natural way by string interactions. In a favorable scenario, this might lead to $\text{CPT}$ violation in the K-K̄ system just below the limits of present experiments.
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    Constraints on Lorentz violation from gravitational Čerenkov radiation
    (Physics Letters B, 2015) Tasson, Jay D.; Kostelecký, V.A.
    Limits on gravitational Čerenkov radiation by cosmic rays are obtained and used to constrain coefficients for Lorentz violation in the gravity sector associated with operators of even mass dimensions, including orientation-dependent effects. We use existing data from cosmic-ray telescopes to obtain conservative two-sided constraints on 80 distinct Lorentz-violating operators of dimensions four, six, and eight, along with conservative one-sided constraints on three others. Existing limits on the nine minimal operators at dimension four are improved by factors of up to a billion, while 74 of our explicit limits represent stringent first constraints on nonminimal operators. Prospects are discussed for future analyses incorporating effects of Lorentz violation in the matter sector, the role of gravitational Čerenkov radiation by high-energy photons, data from gravitational-wave observatories, the tired-light effect, and electromagnetic Čerenkov radiation by gravitons.
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    Riemann-Finsler geometry and Lorentz-violating kinematics
    (Physics Letters B, 2011) Kostelecký, V.A.
    Effective field theories with explicit Lorentz violation are intimately linked to Riemann–Finsler geometry. The quadratic single-fermion restriction of the Standard-Model Extension provides a rich source of pseudo-Riemann–Finsler spacetimes and Riemann–Finsler spaces. An example is presented that is constructed from a 1-form coefficient and has Finsler structure complementary to the Randers structure.
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    Three-parameter Lorentz-violating texture for neutrino mixing
    (Physics Letters B, 2011) Dias, Jorge S.; Kostelecký, V.A.
    A three-parameter model of neutrino oscillations based on a simple Lorentz- and $\text{CPT}$-violating texture is presented. The model is consistent with established data and naturally generates low-energy and neutrino–antineutrino anomalies of the MiniBooNE type. A one-parameter extension incorporates the MINOS anomaly, while a simple texture enhancement accommodates the LSND signal.
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    Background enhancement of $\text{CPT}$ reach at an asymmetric $\phi$ factory
    (Physics Letters B, 2001) Isgur, Nathan; Kostelecký, V.A.; Szczepaniak, Adam P.
    Photoproduction of neutral-kaon pairs is studied from the perspective of $\text{CP}$ and $\text{CPT}$ studies. Interference of the $\text{P}$- and $\text{S}$-waves, with the former due to diffractive $\phi$ production and the latter to $f_{0}/a_{0}$ production, is shown to enhance the $\text{CPT}$ reach. Results are presented of Monte Carlo studies based on rates expected in future experiments.
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    Cross sections and lorentz violation
    (Physics Letters B, 2001) Colladay, Don; Kostelecký, V.A.
    The derivation of cross sections and decay rates in the Lorentz-violating Standard Model extension is discussed. General features of the physics are described, and some conceptual and calculational issues are addressed. As an illustrative example, the cross section for the specific process of electron–positron pair annihilation into two photons is obtained.
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    $\text{CPT}$ violation and baryogenesis
    (Physics Letters B, 1997) Bertolami, O.; Colladay, Don; Kostelecký, V.A.; Potting, R.
    We examine the effects on baryogenesis of spontaneous $\text{CPT}$ violation in a string-based scenario. Under suitable circumstances, certain $\text{CPT}$-violating terms can produce a large baryon asymmetry at the grand-unified scale that reduces to the observed value via sphaleron or other dilution mechanisms.
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    Expectation values, Lorentz invariance, and $\text{CPT}$ in the open bosonic string
    (Physics Letters B, 1996) Potting, R.; Kostelecký, V.A.
    The issue of spontaneous breaking of Lorentz and $\text{CPT}$ invariance is studied in the open bosonic string using a truncation scheme to saturate the string-field action at successively higher levels. We find strong evidence for the existence of extrema of the action with nonzero expectation values for certain fields. The Lorentz- and $\text{CPT}$-preserving solution previously suggested in the literature is confirmed through level 12 in the action. A family of Lorentz-breaking, $\text{CPT}$-preserving solutions of the equations of motion is found to persist and converge through level 18 in the action. Two sequences of solutions spontaneously breaking both Lorentz invariance and $\text{CPT}$ are discussed. The analysis at this level involves the analytical form of over 20,000 terms in the static potential.
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    Tests of direct and indirect $\text{CPT}$ violation at a $\text{B}$ factory
    (Physics Letters B, 1995) Collady, Don; Kostelecký, V.A.
    The issue of testing $\text{CPT}$ invariance at a $\text{B}$ factory is considered. We present asymmetries that permit a clean extraction of quantities parametrizing direct and indirect $\text{CPT}$ violation, using information from $\text{ϒ}(4S)$ decay via coherent $\text{B}_{d}\overline{B}_{d}$ pairs into various final states. Estimates are given of the bounds on $\text{CPT}$ violation that could be obtained in present and planned machines.
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    Lorentz and $\text{CPT}$ violation in top-quark production and decay
    (American Physical Society, 2016) Berger, Michael S.; Kostelecký, V.A.; Liu, Zhi
    The prospects are explored for testing Lorentz and $\text{CPT}$ symmetry in the top-quark sector. We present the relevant Lagrange density, discuss physical observables, and describe the signals to be sought in experiments. For top-antitop pair production via quark or gluon fusion with subsequent semileptonic or hadronic decays, we obtain the matrix element in the presence of Lorentz violation using the narrow-width approximation. The issue of testing $\text{CPT}$ symmetry in the top-quark sector is also addressed. We demonstrate that single-top production and decay is well suited to a search for $\text{CPT}$ violation, and we present the matrix elements for single-top production in each of the four tree-level channels. Our results are applicable to searches for Lorentz violation and studies of $\text{CPT}$ symmetry in collider experiments, including notably high-statistics top-antitop and single-top production at the Large Hadron Collider.
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    Lorentz and $\text{CPT}$ tests with hydrogen, antihydrogen, and related systems
    (American Physical Society, 2015) Vargas, Arnaldo J.; Kostelecký, V.A.
    The potential of precision spectroscopy as a tool in systematic searches for effects of Lorentz and $\text{CPT}$ violation is investigated. Systems considered include hydrogen, antihydrogen, deuterium, positronium, and hydrogen molecules and molecular ions. Perturbative shifts in energy levels and key transition frequencies are derived, allowing for Lorentz-violating operators of arbitrary mass dimensions. Observable effects are deduced from various direct measurements, sidereal and annual variations, comparisons among species, and gravitational responses. We use existing data to place new and improved constraints on nonrelativistic coefficients for Lorentz and $\text{CPT}$ violation, and we provide estimates for the future attainable reach in direct spectroscopy of the various systems or tests with hydrogen and deuterium masers. The results reveal prospective sensitivities to many coefficients unmeasured to date, along with potential improvements of a billionfold or more over certain existing results.
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    Search for Lorentz violation in short-range gravity
    (American Physical Society, 2015) Long, J.C.; Kostelecký, V.A.
    A search for sidereal variations in the force between two planar tungsten oscillators separated by about 80 $\mu m$ sets the first experimental limits on Lorentz violation involving quadratic couplings of the Riemann curvature, consistent with no effect at the level of $10 ^{(-7)}$ $m^{(2)}$.
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    Bipartite Riemann–Finsler geometry and Lorentz violation
    (Elsevier, 2012) Kostelecký, V.A.; Russell, N.; Tso, R.
    Bipartite Riemann–Finsler geometries with complementary Finsler structures are constructed. Calculable examples are presented based on a bilinear-form coefficient for explicit Lorentz violation.
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    Classical kinematics for Lorentz violation
    (Elsevier, 2010) Kostelecký, V.A.; Russell, N.
    Classical point-particle relativistic lagrangians are constructed that generate the momentum–velocity and dispersion relations for quantum wave packets in Lorentz-violating effective field theory.
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    Astrophysical Tests of Lorentz and CPT Violation with Photons
    (IOP Publishing, 2008) Kostelecký, V.A.; Mewes, M.
    A general framework for tests of Lorentz invariance with electromagnetic waves is presented, allowing for operators of arbitrary mass dimension. Signatures of Lorentz violations include vacuum birefringence, vacuum dispersion, and anisotropies. Sensitive searches for violations using sources such as active galaxies, gamma-ray bursts, and the cosmic microwave background are discussed. Direction-dependent dispersion constraints are obtained on operators of dimension 6 and 8 using gamma-ray bursts and the blazar Markarian 501. Stringent constraints on operators of dimension 3 are found using 5 year data from the Wilkinson Microwave Anisotropy Probe. No evidence appears for isotropic Lorentz violation, while some support at 1 σ is found for anisotropic violation.
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    Spontaneous Lorentz violation and nonpolynomial interactions
    (Elsevier, 2005) Altschul, B.; Kostelecký, V.A.
    Gauge-noninvariant vector field theories with superficially nonrenormalizable nonpolynomial interactions are studied. We show that nontrivial relevant and stable theories have spontaneous Lorentz violation, and we present a large class of asymptotically free theories. The Nambu–Goldstone modes of these theories can be identified with the photon, with potential experimental implications.
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    Limit on Lorentz and $CPT$ Violation of the Neutron Using a Two-Species Noble-Gas Maser
    (American Physical Society, 2000) Bear, D.; Stoner, R.E.; Walsworth, R.L.; Kostelecký, V.A.; Lane, C.D.
    A search for sidereal variations in the frequency difference between co-located $^{129}\text{Xe}$ and $^{3}\text{He}$ Zeeman masers sets the most stringent limit to date on leading-order Lorentz and $CPT$ violation involving the neutron, consistent with no effect at the level of $10^{−31}$ $\text{GeV}$.