4,304 research outputs found
Quark Loop Contributions to Neutron, Deuteron, and Mercury EDMs from Supersymmetry without R parity
We present a detailed analysis of the neutron, deuteron and mercury electric
dipole moment from supersymmetry without R parity, focusing on the quark-scalar
loop contributions. Being proportional to top Yukawa and top mass, such
contributions are often large. Analytical expressions illustrating the explicit
role of the R-parity violating parameters are given following perturbative
diagonalization of mass-squared matrices for the scalars. Dominant
contributions come from the combinations for which
we obtain robust bounds. It turns out that neutron and deuteron EDMs receive
much stronger contributions than mercury EDM and any null result at the future
deuteron EDM experiment or Los Alamos neutron EDM experiment can lead to
extra-ordinary constraints on RPV parameter space. Even if R-parity violating
couplings are real, CKM phase does induce RPV contribution and for some cases
such a contribution is as strong as contribution from phases in the R-parity
violating couplings.Hence, we have bounds directly on even if the RPV parameters are all real.
Interestingly, even if slepton mass and/or is as high as 1 TeV, it
still leads to neutron EDM that is an order of magnitude larger than the
sensitivity at Los Alamos experiment. Since the results are not much sensitive
to , our constraints will survive even if other observables tighten
the constraints on .Comment: 16 pages, 10 figures, accepted for publication in Physical Review
Foldy-Wouthuysen transformation for a Dirac-Pauli dyon and the Thomas-Bargmann-Michel-Telegdi equation
The classical dynamics for a charged point particle with intrinsic spin is
governed by a relativistic Hamiltonian for the orbital motion and by the
Thomas-Bargmann-Michel-Telegdi equation for the precession of the spin. It is
natural to ask whether the classical Hamiltonian (with both the orbital and
spin parts) is consistent with that in the relativistic quantum theory for a
spin-1/2 charged particle, which is described by the Dirac equation. In the
low-energy limit, up to terms of the 7th order in ( and
is the particle mass), we investigate the Foldy-Wouthuysen (FW) transformation
of the Dirac Hamiltonian in the presence of homogeneous and static
electromagnetic fields and show that it is indeed in agreement with the
classical Hamiltonian with the gyromagnetic ratio being equal to 2. Through
electromagnetic duality, this result can be generalized for a spin-1/2 dyon,
which has both electric and magnetic charges and thus possesses both intrinsic
electric and magnetic dipole moments. Furthermore, the relativistic quantum
theory for a spin-1/2 dyon with arbitrary values of the gyromagnetic and
gyroelectric ratios can be described by the Dirac-Pauli equation, which is the
Dirac equation with augmentation for the anomalous electric and anomalous
magnetic dipole moments. The FW transformation of the Dirac-Pauli Hamiltonian
is shown, up to the 7th order again, to be also in accord with the classical
Hamiltonian.Comment: 18 page
Decoherent Scattering of Light Particles in a D-Brane Background
We discuss the scattering of two light particles in a D-brane background. It
is known that, if one light particle strikes the D brane at small impact
parameter, quantum recoil effects induce entanglement entropy in both the
excited D brane and the scattered particle. In this paper we compute the
asymptotic `out' state of a second light particle scattering off the D brane at
large impact parameter, showing that it also becomes mixed as a consequence of
quantum D-brane recoil effects. We interpret this as a non-factorizing
contribution to the superscattering operator S-dollar for the two light
particles in a Liouville D-brane background, that appears when quantum D-brane
excitations are taken into account.Comment: 18 pages LATEX, one figure (incorporated
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Common DNA sequence variation influences 3-dimensional conformation of the human genome.
BACKGROUND:The 3-dimensional (3D) conformation of chromatin inside the nucleus is integral to a variety of nuclear processes including transcriptional regulation, DNA replication, and DNA damage repair. Aberrations in 3D chromatin conformation have been implicated in developmental abnormalities and cancer. Despite the importance of 3D chromatin conformation to cellular function and human health, little is known about how 3D chromatin conformation varies in the human population, or whether DNA sequence variation between individuals influences 3D chromatin conformation. RESULTS:To address these questions, we perform Hi-C on lymphoblastoid cell lines from 20 individuals. We identify thousands of regions across the genome where 3D chromatin conformation varies between individuals and find that this variation is often accompanied by variation in gene expression, histone modifications, and transcription factor binding. Moreover, we find that DNA sequence variation influences several features of 3D chromatin conformation including loop strength, contact insulation, contact directionality, and density of local cis contacts. We map hundreds of quantitative trait loci associated with 3D chromatin features and find evidence that some of these same variants are associated at modest levels with other molecular phenotypes as well as complex disease risk. CONCLUSION:Our results demonstrate that common DNA sequence variants can influence 3D chromatin conformation, pointing to a more pervasive role for 3D chromatin conformation in human phenotypic variation than previously recognized
On the unitarity of higher-dervative and nonlocal theories
We consider two simple models of higher-derivative and nonlocal quantu
systems.It is shown that, contrary to some claims found in literature, they can
be made unitary.Comment: 8 pages, no figure
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