From Euclidean to Minkowski space with the Cauchy-Riemann equations

We present an elementary method to obtain Green's functions in non-perturbative quantum field theory in Minkowski space from calculated Green's functions in Euclidean space. Since in non-perturbative field theory the analytical structure of amplitudes is many times unknown, especially in the presence of confined fields, dispersive representations suffer from systematic uncertainties. Therefore we suggest to use the Cauchy-Riemann equations, that perform the analytical continuation without assuming global information on the function in the entire complex plane, only in the region through which the equations are solved. We use as example the quark propagator in Landau gauge Quantum Chromodynamics, that is known from lattice and Dyson-Schwinger studies in Euclidean space. The drawback of the method is the instability of the Cauchy-Riemann equations to high-frequency noise, that makes difficult to achieve good accuracy. We also point out a few curiosities related to the Wick rotation.Comment: 12 pages in EPJ double-column format, 16 figures. This version: added paragraph, two reference

Satellite galaxies in semi-analytic models of galaxy formation with sterile neutrino dark matter

The sterile neutrino is a viable dark matter candidate that can be produced in the early Universe via non-equilibrium processes, and would therefore possess a highly non-thermal spectrum of primordial velocities. In this paper we analyse the process of structure formation with this class of dark matter particles. To this end we construct primordial dark matter power spectra as a function of the lepton asymmetry, L6, that is present in the primordial plasma and leads to resonant sterile neutrino production. We compare these power spectra with those of thermally produced dark matter particles and show that resonantly produced sterile neutrinos are much colder than their thermal relic counterparts. We also demonstrate that the shape of these power spectra is not determined by the free-streaming scale alone. We then use the power spectra as an input for semi-analytic models of galaxy formation in order to predict the number of luminous satellite galaxies in a Milky Way-like halo. By assuming that the mass of the Milky Way halo must be no more than 2 × 1012 M⊙ (the adopted upper bound based on current astronomical observations) we are able to constrain the value of L6 for Ms ≤ 8 keV. We also show that the range of L6 that is in best agreement with the 3.5 keV line (if produced by decays of 7 keV sterile neutrino) requires that the Milky Way halo has a mass no smaller than 1.5 × 1012 M⊙. Finally, we compare the power spectra obtained by direct integration of the Boltzmann equations for a non-resonantly produced sterile neutrino with the fitting formula of Viel et al. and find that the latter significantly underestimates the power amplitude on scales relevant to satellite galaxies

Proton Decay in Minimal Supersymmetric SU(5)

We systematically study proton decay in the minimal supersymmetric SU(5) grand unified theory. We find that although the available parameter space of soft masses and mixings is quite constrained, the theory is still in accord with experiment.Comment: 12 pages, uses axodraw.sty, few more comments, one new referenc

Predictors of Cervical Cancer Screening among Infrequently Screened Women Completing Human Papillomavirus Self-Collection: My Body My Test-1

Background: Approximately one-half of cervical cancer cases in the United States occur in underscreened or never-screened women. We examined predictors to completing Papanicolaou (Pap) testing and whether a positive human papillomavirus (HPV) self-collection result affects Pap testing adherence among underscreened women. Materials and Methods: Low-income women aged 30-65 years who reported no Pap testing in ≥4 years were recruited in North Carolina. Knowledge, attitudes, and barriers regarding cervical cancer and Pap testing were assessed by telephone questionnaires. We mailed self-collection kits for HPV testing and provided information regarding where to obtain affordable Pap testing. Participants received $45 for completing all activities. We used multivariable logistic regression to assess the predictors of longer reported time since last Pap (≥10 vs. 4-9 years) and of completion of Pap testing following study enrollment (follow-up Pap). Results: Participants (n = 230) were primarily black (55%), uninsured (64%), and with ≤high school education (59%). Cost and finding an affordable clinic were the most commonly reported barriers to screening. White women and those with ≤high school education reported longer intervals since last Pap test. Half of the participants reported completing a follow-up Pap test (55%). Women with a positive HPV self-collection were five times more likely to report completing a follow-up Pap test than those with negative self-collection (odds ratio = 5.1, 95% confidence interval 1.4-25.7). Conclusions: Improving awareness of resources for affordable screening could increase cervical cancer screening in underserved women. Home-based HPV self-collection represents an opportunity to re-engage infrequently screened women into preventive screening services

A new variational approach to the stability of gravitational systems

We consider the three dimensional gravitational Vlasov Poisson system which describes the mechanical state of a stellar system subject to its own gravity. A well-known conjecture in astrophysics is that the steady state solutions which are nonincreasing functions of their microscopic energy are nonlinearly stable by the flow. This was proved at the linear level by several authors based on the pioneering work by Antonov in 1961. Since then, standard variational techniques based on concentration compactness methods as introduced by P.-L. Lions in 1983 have led to the nonlinear stability of subclasses of stationary solutions of ground state type. In this paper, inspired by pioneering works from the physics litterature (Lynden-Bell 94, Wiechen-Ziegler-Schindler MNRAS 88, Aly MNRAS 89), we use the monotonicity of the Hamiltonian under generalized symmetric rearrangement transformations to prove that non increasing steady solutions are local minimizer of the Hamiltonian under equimeasurable constraints, and extract compactness from suitable minimizing sequences. This implies the nonlinear stability of nonincreasing anisotropic steady states under radially symmetric perturbations

On Neutrino Masses and a Low Breaking Scale of Left-Right Symmetry

In left-right symmetric models (LRSM) the light neutrino masses arise from two sources: the seesaw mechanism and a VEV of an SU(2)$_L$ triplet. If the left-right symmetry breaking, $v_R$, is low, v_R\lsim15\TeV, the contributions to the light neutrino masses from both the seesaw mechanism and the triplet Yukawa couplings are expected to be well above the experimental bounds. We present a minimal LRSM with an additional U(1) symmetry in which the masses induced by the two sources are below the eV scale and the two-fold problem is solved. We further show that, if the U(1) symmetry is also responsible for the lepton flavor structure, the model yields a small mixing angle within the first two lepton generations.Comment: 18 pages references added published versio

RS1, Custodial Isospin and Precision Tests

We study precision electroweak constraints within a RS1 model with gauge fields and fermions in the bulk. The electroweak gauge symmetry is enhanced to SU(2)_L \times SU(2)_R \times U(1)_{B-L}, thereby providing a custodial isospin symmetry sufficient to suppress excessive contributions to the T parameter. We then construct complete models, complying with all electroweak constraints, for solving the hierarchy problem, without supersymmetry or large hierarchies in the fundamental couplings. Using the AdS/CFT correspondence our models can be interpreted as dual to a strongly coupled conformal Higgs sector with global custodial symmetry, gauge and fermionic matter being fundamental fields external to the CFT. This scenario has interesting collider signals, distinct from other RS models in the literature.Comment: 32 pages, 6 figures, latex2e, minor changes, references adde

Lepton Masses and Mixing in a Left-Right Symmetric Model with a TeV-scale Gravity

We construct a left-right symmetric (LRS) model in five dimensions which accounts naturally for the lepton flavor parameters. The fifth dimension is described by an orbifold, S_1/Z_2 times Z'_2, with a typical size of order TeV^{-1}. The fundamental scale is of order 25 TeV which implies that the gauge hierarchy problem is ameliorated. In addition the LRS breaking scale is of order few TeV which implies that interactions beyond those of the standard model are accessible to near future experiments. Leptons of different representations are localized around different orbifold fixed points. This explains, through the Arkani-Hamed-Schmaltz mechanism, the smallness of the tau mass compared to the electroweak breaking scale. An additional U(1) horizontal symmetry, broken by small parameters, yields the hierarchy in the charged lepton masses, strong suppression of the light neutrino masses and accounts for the mixing parameters. The model yields several unique predictions. In particular, the branching ratio for the lepton flavor violating process mu^- --> e^+ e^- e^- is comparable with its present experimental sensitivity.Comment: 21 pages, 1 figure, references added, discussion on the predictiveness of the model in the generic non-universal case added, to appear in PR

Adsorption of mono- and multivalent cat- and anions on DNA molecules

Adsorption of monovalent and multivalent cat- and anions on a deoxyribose nucleic acid (DNA) molecule from a salt solution is investigated by computer simulation. The ions are modelled as charged hard spheres, the DNA molecule as a point charge pattern following the double-helical phosphate strands. The geometrical shape of the DNA molecules is modelled on different levels ranging from a simple cylindrical shape to structured models which include the major and minor grooves between the phosphate strands. The densities of the ions adsorbed on the phosphate strands, in the major and in the minor grooves are calculated. First, we find that the adsorption pattern on the DNA surface depends strongly on its geometrical shape: counterions adsorb preferentially along the phosphate strands for a cylindrical model shape, but in the minor groove for a geometrically structured model. Second, we find that an addition of monovalent salt ions results in an increase of the charge density in the minor groove while the total charge density of ions adsorbed in the major groove stays unchanged. The adsorbed ion densities are highly structured along the minor groove while they are almost smeared along the major groove. Furthermore, for a fixed amount of added salt, the major groove cationic charge is independent on the counterion valency. For increasing salt concentration the major groove is neutralized while the total charge adsorbed in the minor groove is constant. DNA overcharging is detected for multivalent salt. Simulations for a larger ion radii, which mimic the effect of the ion hydration, indicate an increased adsorbtion of cations in the major groove.Comment: 34 pages with 14 figure