38,800 research outputs found
The phenomenology of electric dipole moments in models of scalar leptoquarks
We study the phenomenology of electric dipole moments (EDMs) induced in
various scalar leptoquark models. We consider generic leptoquark couplings to
quarks and leptons and match to Standard Model effective field theory. After
evolving the resulting operators to low energies, we connect to EDM experiments
by using up-to-date hadronic, nuclear, and atomic matrix elements. We show that
current experimental limits set strong constraints on the possible CP-violating
phases in leptoquark models. Depending on the quarks and leptons involved in
the interaction, the existing searches for EDMs of leptons, nucleons, atoms,
and molecules all play a role in constraining the CP-violating couplings. We
discuss the impact of hadronic and nuclear uncertainties as well as the
sensitivities that can be achieved with future EDM experiments. Finally, we
study the impact of EDM constraints on a specific leptoquark model that can
explain the recent -physics anomalies.Comment: Published versio
Transport in Almost Integrable Models: Perturbed Heisenberg Chains
The heat conductivity kappa(T) of integrable models, like the one-dimensional
spin-1/2 nearest-neighbor Heisenberg model, is infinite even at finite
temperatures as a consequence of the conservation laws associated with
integrability. Small perturbations lead to finite but large transport
coefficients which we calculate perturbatively using exact diagonalization and
moment expansions. We show that there are two different classes of
perturbations. While an interchain coupling of strength J_perp leads to
kappa(T) propto 1/J_perp^2 as expected from simple golden-rule arguments, we
obtain a much larger kappa(T) propto 1/J'^4 for a weak next-nearest neighbor
interaction J'. This can be explained by a new approximate conservation law of
the J-J' Heisenberg chain.Comment: 4 pages, several minor modifications, title change
Recommended from our members
"Things Are Different Now But": Older LGBT Adults' Experiences and Unmet Needs in Health Care.
Background: Approximately 2.7 million U.S. older adults self-identify as lesbian, gay, bisexual, and transgender (LGBT). Many felt unsafe revealing their sexual orientation until relatively recently, and may still not be "out" to medical providers. The aim of this study was to increase understanding of the experiences and needs of older LGBT adults when accessing care. Method: Individual semistructured interviews were conducted with 10 individuals aged 65 years or older from a local LGBT community. Interviews were audio taped and transcribed verbatim. Transcripts were analyzed via thematic analysis. Results: Major themes were "Outness," "Things are Different Now," and "Additional Resources." These describe participant comfort with being "out"; how treatment they received changed over time, and needed services or other options from the community. Conclusion: While many older LGBT adults are accustomed to navigating social mores to avoid negative experiences, nurses as well as other health care providers must be prepared to create trusting relationships with these individuals to provide truly comprehensive care
Strongly Correlated Two-Photon Transport in One-Dimensional Waveguide Coupled to A Two-Level System
We show that two-photon transport is strongly correlated in one-dimensional
waveguide coupled to a two-level system. The exact S-matrix is constructed
using a generalized Bethe-Ansatz technique. We show that the scattering
eigenstates of this system include a two-photon bound state that passes through
the two-level system as a composite single particle. Also, the two-level system
can induce effective attractive or repulsive interactions in space for photons.
This general procedure can be applied to the Anderson model as well.Comment: 12 pages. 3 figures. Accepted by Physical Review Letter
Long-term Running Experience with the Silicon Micro-strip Tracker at the D{\O} detector
The SiliconMicro-strip Tracker (SMT) at the D{\O} experiment in the Fermilab
Tevatron collider has been operating since 2001. In 2006, an additional layer,
referred to as 'Layer 0', was installed to improve impact parameter resolution
and compensate for detector degradation due to radiation damage to the original
innermost SMT layer. The SMT detector provides valuable tracking and vertexing
information for the experiment. This contribution will highlight aspects of the
long term operation of the SMT, including the impact of the silicon readout
test-stand. Due to the full integration of the test-stand into the D{\O}
trigger framework, this test-stand provides an advantageous tool for training
of new experts and studying subtle effects in the SMT while minimizing impact
on the global data acquisition.Comment: Proceedings of TIPP 2011 (Technology and Instrumentation for Particle
Physics 2011), June 9-14 2011, Chicago, US
Ionic and Electronic Conductivity of Nanostructured, Samaria-Doped Ceria
The ionic and electronic conductivities of samaria doped ceria electrolytes, Ce_(0.85)Sm_(0.15)O_(1.925−δ), with nanometric grain size have been evaluated. Nanostructured bulk specimens were obtained using a combination of high specific-surface-area starting materials and suitable sintering profiles under conventional, pressureless conditions. Bulk specimens with relatively high density (≥92% of theoretical density) and low medium grain size (as small as 33 nm) were achieved. Electrical A.C. impedance spectra were recorded over wide temperature (150 to 650°C) and oxygen partial pressure ranges (0.21 to 10^(−31) atm). Under all measurement conditions the total conductivity decreased monotonically with decreasing grain size. In both the electrolytic and mixed conducting regimes this behavior is attributed to the high number density of high resistance grain boundaries. The results suggest a possible variation in effective grain boundary width with grain size, as well as a possible variation in specific grain boundary resistance with decreasing oxygen partial pressure. No evidence appears for either enhanced reducibility or enhanced electronic conductivity upon nanostructuring
Does three-tangle properly quantify the three-party entanglement for Greenberger-Horne-Zeilinger-type states?
Some mixed states composed of only GHZ states can be expressed in terms of
only W-states. This fact implies that such states have vanishing three-tangle.
One of such rank-3 states, , is explicitly presented in this paper.
These results are used to compute analytically the three-tangle of a rank-4
mixed state composed of four GHZ states. This analysis with
considering Bloch sphere of qudit system allows us to derive the
hyper-polyhedron. It is shown that the states in this hyper-polyhedron have
vanishing three-tangle. Computing the one-tangles for and ,
we prove the monogamy inequality explicitly. Making use of the fact that the
three-tangle of is zero, we try to explain why the W-class in the
whole mixed states is not of measure zero contrary to the case of pure states.Comment: 10 pages, no figure V2: new calculational results are included. 11
pages: V3 accepted in the Rapid Communication of PRA, 4 pages (two column
The intrinsic strangeness and charm of the nucleon using improved staggered fermions
We calculate the intrinsic strangeness of the nucleon, - ,
using the MILC library of improved staggered gauge configurations using the
Asqtad and HISQ actions. Additionally, we present a preliminary calculation of
the intrinsic charm of the nucleon using the HISQ action with dynamical charm.
The calculation is done with a method which incorporates features of both
commonly-used methods, the direct evaluation of the three-point function and
the application of the Feynman- Hellman theorem. We present an improvement on
this method that further reduces the statistical error, and check the result
from this hybrid method against the other two methods and find that they are
consistent. The values for and found here, together with
perturbative results for heavy quarks, show that dark matter scattering through
Higgs-like exchange receives roughly equal contributions from all heavy quark
flavors.Comment: 17 pages, 14 figure
Partially composite 2-Higgs-doublet model
In the extra dimensional scenarios with gauge fields in the bulk, the
Kaluza-Klein (KK) gauge bosons can induce Nambu-Jona-Lasinio (NJL) type
attractive four-fermion interactions, which can break electroweak symmetry
dynamically with accompanying composite Higgs fields. We consider a possibility
that electroweak symmetry breaking (EWSB) is triggered by both a fundamental
Higgs and a composite Higgs arising in a dynamical symmetry breaking mechanism
induced by a new strong dynamics. The resulting Higgs sector is a partially
composite two-Higgs doublet model with specific boundary conditions on the
coupling and mass parameters originating at a compositeness scale .
The phenomenology of this model is discussed including the collider
phenomenology at LHC and ILC.Comment: To appear in the proceeding of LCWS06, Bangalore, Indi
- …