Assuming the same form of all mass matrices as motivated by quark-lepton symmetry, we discuss conditions under which bilarge mixing in the lepton sector can be obtained with a minimal amount of fine-tuning requirements for possible models. We assume hierarchical mass matrices, dominated by the 3-3 element, with off-diagonal elements much smaller than the larger neighboring diagonal element. Characteristic features of this scenario are strong hierarchy in masses of right-handed neutrinos, and comparable contributions of both lighter right-handed neutrinos to the resulting left-handed neutrino Majorana mass matrix. Because of obvious quark-lepton symmetry, this approach can be embedded into grand unified theories. The mass of the lightest neutrino does not depend on details of a model in the leading order. The right-handed neutrino scale can be identified with the GUT scale in which case the mass of the lightest neutrino is given as $(m_{\mathrm{t}\mathrm{o}\mathrm{p}}^2/M_{\mathrm{G}\mathrm{U}\mathrm{T}})|U_{\tau 1}{|}^2$.

This paper is a response to the preceding Comment by Klapdor-Kleingrothaus, Dietz, and Krivosheina. The criticisms are confronted, and the questions raised are answered. We demonstrate that the lower limit quoted by IGEX, , is correct and that there was no “arithmetical error” as claimed in the “Critical View” article.

Recently, a paper entitled “The IGEX neutrinoless double-beta decay experiment: Prospects for next generation experiments” has been published []. In view of the recently reported evidence for neutrinoless double-beta decay [; ; ], it is particularly unfortunate that the IGEX paper is rather incomplete in its presentation. We would like to point out in this Comment that and why it would be highly desirable to make more details about the experimental conditions and the analysis of IGEX available. We list some of the main points, which require further explanation. We also point to an arithmetic mistake in the analysis of the IGEX data, the consequence of which are too high half-life limits given in that paper.

We present a calculation of the complete electroweak $\mathcal{O}(\alpha )$ corrections to $p\stackrel{(-)}{p}\to W^{\pm }\to {\ell }^{\pm }\nu X$ ($\ell =e,\mu$) in the standard model of electroweak interactions, focusing on those corrections which do not contribute in the pole approximation. We study in detail the effect of these corrections on the transverse mass distribution, the $W$-width measurement, and the transverse mass ratio and cross section ratio of $W$ and $Z$ bosons.

We consider the Kawai-Lewellen-Tye (KLT) factorizations of gravity scalar-leg amplitudes into products of Yang-Mills scalar-leg amplitudes. We check and examine the factorizations at $\mathcal{O}(1)$ in ${\alpha }^{\prime }$ and extend the analysis by considering KLT mapping in the case of generic effective Lagrangians for Yang-Mills theory and gravity.

We study issues of duality and dual equivalence in noncommutative manifolds. In particular, the question of dual equivalence for the actions of the noncommutative extensions of the self-dual model in 3D space-time and the Maxwell-Chern-Simons model is investigated. We show that former model is not dual equivalent to the noncommutative extension of the Maxwell-Chern-Simons model, as widely believed, but a deformed version of it that is disclosed here. Our results are not restricted to any finite order in the Seiberg-Witten expansion involving the noncommutative parameter $\theta$.

Light-front quantization has important advantages for describing relativistic statistical systems, particularly systems for which boost invariance is essential, such as the fireball created in a heavy ion collision. In this paper we develop light-front field theory at finite temperature and density with special attention to quantum chromodynamics. We construct the most general form of the statistical operator allowed by the Poincaré algebra and show that there are no zero-mode related problems when describing phase transitions. We then demonstrate a direct connection between densities in light-front thermal field theory and the parton distributions measured in hard scattering experiments. Our approach thus generalizes the concept of a parton distribution to finite temperature. In light-front quantization, the gauge-invariant Green’s functions of a quark in a medium can be defined in terms of just 2-component spinors and have a much simpler spinor structure than the equal-time fermion propagator. From the Green’s function, we introduce the new concept of a light-front density matrix, whose matrix elements are related to forward and to off-diagonal parton distributions. Furthermore, we explain how thermodynamic quantities can be calculated in discretized light cone quantization, which is applicable at high chemical potential and is not plagued by the fermion-doubling problem.

A thermodynamic argument is presented suggesting that near-extremal spinning D1-D5-P black strings become unstable when their angular momentum exceeds $J_{\mathrm{c}\mathrm{r}\mathrm{i}\mathrm{t}}=3Q_1{Q}_5/2\sqrt{2}$. In contrast, the dimensionally reduced black holes are thermodynamically stable. The proposed instability involves a phase in which the spin angular momentum above $J_{\mathrm{c}\mathrm{r}\mathrm{i}\mathrm{t}}$ is transferred to gyration of the string in space, i.e., to orbital angular momentum of parts of the string about the mean location in space. Thus the string becomes a rotating helical coil. We note that an instability of this form would yield a counter-example to the Gubser-Mitra conjecture, which proposes a particular link between dynamic black string instabilities and the thermodynamics of black strings. There may also be other instabilities associated with radiation modes of various fields. Our arguments also apply to the D-brane bound states associated with these black strings in weakly coupled string theory.

The first objective of this work is to obtain practical prescriptions to calculate the absorption of mass and angular momentum by a black hole when external processes produce gravitational radiation. These prescriptions are formulated in the time domain (in contrast with the frequency-domain formalism of Teukolsky and Press) within the framework of black-hole perturbation theory. Two such prescriptions are presented. The first is based on the Teukolsky equation and it applies to general (rotating) black holes. The second is based on the Regge-Wheeler and Zerilli equations and it applies to nonrotating black holes. The second objective of this work is to apply the time-domain absorption formalisms to situations in which the black hole is either small or slowly moving; the mass of the black hole is then assumed to be much smaller than the radius of curvature of the external spacetime in which the hole moves. In the context of this small-hole/slow-motion approximation, the equations of black-hole perturbation theory can be solved analytically, and explicit expressions can be obtained for the absorption of mass and angular momentum. The changes in the black-hole parameters can then be understood in terms of an interaction between the tidal gravitational fields supplied by the external universe and the hole’s tidally-induced mass and current quadrupole moments. For a nonrotating black hole the quadrupole moments are proportional to the rate of change of the tidal fields on the hole’s world line. For a rotating black hole they are proportional to the tidal fields themselves. When placed in identical environments, a rotating black hole absorbs more energy and angular momentum than a nonrotating black hole.

We show that the microscopic black hole entropy formula based on Virasoro algebra can be derived from the usual properties of stationary Killing horizons alone and the absence of singularities of curvature invariants on them. In such a way some usual additional assumptions are shown to be fulfilled. In addition, for all quantities power expansion near the horizon and thus explicit insight of the limiting procedure is given. More important the near horizon conformal symmetry proposed by Carlip together with its consequences on microscopic entropy is given a clear geometric origin.

X-ray and Sunyaev-Zel’dovich data of clusters of galaxies enable to construct a test of the distance duality relation between the angular and luminosity distances. We argue that such a test on large cluster samples may be of importance, as a consistency check, while trying to distinguish between various models accounting for the acceleration of the universe. The analysis of a data set of 18 clusters shows no significant violation of this relation for a $\Lambda$-Cold Dark Matter (CDM) model. The origin and amplitude of systematic effects and the possibility to increase the precision of this method are discussed.

We study the 3-point functions generated at recombination in the squeezed triangle limit, when one mode has a wavelength much larger than the other two and is outside the horizon. The presence of the long-wavelength mode cannot change the physics inside the horizon but modifies how a late time observer sees the anisotropies. The effect of the long-wavelength mode can be divided into a redefinition of time and spatial scales, a Shapiro time delay and gravitational lensing. The separation is gauge dependent but helps develop intuition. We show that the resulting 3-point function corresponds to an $f_{\mathrm{N}\mathrm{L}}<1$ and that its shape is different from that created by the $f_{\mathrm{N}\mathrm{L}}$ (or local) model.

The Laser Interferometer Space Antenna will detect thousands of gravitational wave sources. Many of these sources will be overlapping in the sense that their signals will have a nonzero cross correlation. Such overlaps lead to source confusion, which adversely affects how well we can extract information about the individual sources. Here we study how source confusion impacts parameter estimation for galactic compact binaries, with emphasis on the effects of the number of overlaping sources, the time of observation, the gravitational wave frequencies of the sources, and the degree of the signal correlations. Our main findings are that the parameter resolution decays exponentially with the number of overlapping sources and superexponentially with the degree of cross correlation. We also find that an extended mission lifetime is key to disentangling the source confusion as the parameter resolution for overlapping sources improves much faster than the usual square root of the observation time.

High-precision interpolation of LISA phase measurements allows signal reconstruction and formulation of time-delay interferometry (TDI) combinations to be conducted in postprocessing. The reconstruction is based on phase measurements made at approximately 10 Hz (for a 1 Hz signal bandwidth) at regular intervals independent of the TDI delay times. Interpolation introduces an error less than $1\times {10}^{-8}$ with continuous data segments as short as 2 s in duration. The 10 Hz sampling rate represents an increase from the 2 Hz sampling rate needed for the original implementation of TDI. The advantages of this technique include increased flexibility of the data analysis and significantly simplified hardware.

The static limit of Lorentz-violating electrodynamics in vacuum and in media is investigated. Features of the general solutions include the need for unconventional boundary conditions and the mixing of electrostatic and magnetostatic effects. Explicit solutions are provided for some simple cases. Electromagnetostatics experiments show promise for improving existing sensitivities to parity-odd coefficients for Lorentz violation in the photon sector.

The sum of the $CP$-violating asymmetries $A_{\Omega }$ and $A_{\Lambda }$ in the decay sequence $\Omega \to \Lambda K$, $\Lambda \to p\pi$ is presently being measured by the E871 experiment. We evaluate contributions to $A_{\Omega }$ from the standard model and from possible new physics and find them to be smaller than the corresponding contributions to $A_{\Lambda }$, although not negligibly so. We also show that the partial-rate asymmetry in $\Omega \to \Lambda K$ is nonvanishing due to final-state interactions. Taking into account constraints from kaon data, we discuss how the upcoming result of E871 and future measurements may probe the various contributions to the observables.

The implementation of the little Higgs mechanism to solve the hierarchy problem provides an interesting guiding principle to build particle physics models beyond the electroweak scale. Most model building works, however, do not pay much attention to the fermionic sector. Through a case example, we illustrate how a complete and consistent fermionic sector of the TeV effective field theory may actually be largely dictated by the gauge structure of the model. The completed fermionic sector has a specific flavor physics structure, and many phenomenological constraints on the model can thus be obtained beyond gauge, Higgs, and top physics. We take a first look at some of the quark sector constraints.

We consider the collider signature of right-handed neutrinos propagating in $\delta$ (large) extra dimensions, and interacting with standard model fields only through a Yukawa coupling to the left-handed neutrino and the Higgs boson. These theories are attractive as they can explain the smallness of the neutrino mass, as has already been shown. We show that if $\delta$ is bigger than two, it can result in an enhancement in the production rate of the Higgs boson, decaying either invisibly or to a $b$ anti-$b$ quark pair, associated with an isolated high $p_T$ charged lepton and missing transverse energy at future hadron colliders, such as the LHC. The enhancement is due to the large number of Kaluza-Klein neutrinos produced in the final state. The observation of the signal event would provide an opportunity to distinguish between the normal and inverted neutrino mass hierarchies, and to determine the absolute scale of neutrino masses by measuring the asymmetry of the observed event numbers in the electron and muon channels.

The semi-inclusive deep inelastic scattering (SIDIS) process is considered. A theoretical procedure is proposed allowing the direct extraction from the SIDIS data of the first moments of the polarized valence distributions and of the first moment difference of the light sea quark polarized distributions in the next to leading QCD order. The validity of the procedure is confirmed by the respective simulations.