Showing papers in "Physical Review D in 2011"
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TL;DR: In this article, the authors considered a modified theory of gravity, where the gravitational Lagrangian is given by an arbitrary function of the Ricci scalar and of the trace of the stress-energy tensor.
Abstract: We consider $f(R,T)$ modified theories of gravity, where the gravitational Lagrangian is given by an arbitrary function of the Ricci scalar $R$ and of the trace of the stress-energy tensor $T$. We obtain the gravitational field equations in the metric formalism, as well as the equations of motion for test particles, which follow from the covariant divergence of the stress-energy tensor. Generally, the gravitational field equations depend on the nature of the matter source. The field equations of several particular models, corresponding to some explicit forms of the function $f(R,T)$, are also presented. An important case, which is analyzed in detail, is represented by scalar field models. We write down the action and briefly consider the cosmological implications of the $f(R,{T}^{\ensuremath{\phi}})$ models, where ${T}^{\ensuremath{\phi}}$ is the trace of the stress-energy tensor of a self-interacting scalar field. The equations of motion of the test particles are also obtained from a variational principle. The motion of massive test particles is nongeodesic, and takes place in the presence of an extra-force orthogonal to the four velocity. The Newtonian limit of the equation of motion is further analyzed. Finally, we provide a constraint on the magnitude of the extra acceleration by analyzing the perihelion precession of the planet Mercury in the framework of the present model.
1,833 citations
TL;DR: In this article, a reevaluation applies to all reactor neutrino experiments and the compatibility of their results with the existence of a fourth nonstandard neutrinos state driving neutrini oscillations at short distances is discussed.
Abstract: Recently, new reactor antineutrino spectra have been provided for $^{235}\mathrm{U}$, $^{239}\mathrm{Pu}$, $^{241}\mathrm{Pu}$, and $^{238}\mathrm{U}$, increasing the mean flux by about 3%. To a good approximation, this reevaluation applies to all reactor neutrino experiments. The synthesis of published experiments at reactor-detector distances $l100\text{ }\text{ }\mathrm{m}$ leads to a ratio of observed event rate to predicted rate of $0.976\ifmmode\pm\else\textpm\fi{}0.024$. With our new flux evaluation, this ratio shifts to $0.943\ifmmode\pm\else\textpm\fi{}0.023$, leading to a deviation from unity at 98.6% C.L. which we call the reactor antineutrino anomaly. The compatibility of our results with the existence of a fourth nonstandard neutrino state driving neutrino oscillations at short distances is discussed. The combined analysis of reactor data, gallium solar neutrino calibration experiments, and MiniBooNE-$\ensuremath{
u}$ data disfavors the no-oscillation hypothesis at 99.8% C.L. The oscillation parameters are such that $|\ensuremath{\Delta}{m}_{\mathrm{new}}^{2}|g1.5\text{ }\text{ }{\mathrm{eV}}^{2}$ (95%) and ${sin }^{2}(2{\ensuremath{\theta}}_{\mathrm{new}})=0.14\ifmmode\pm\else\textpm\fi{}0.08$ (95%). Constraints on the ${\ensuremath{\theta}}_{13}$ neutrino mixing angle are revised.
1,257 citations
TL;DR: In this article, the most general scalar field theories with second-order field equations are derived from linear combinations of Lagrangians made by multiplying a particular form of the Galileon Lagrangian by an arbitrary scalar function of the field and its first derivatives.
Abstract: We determine the most general scalar field theories which have an action that depends on derivatives of order two or less, and have equations of motion that stay second order and lower on flat space-time. We show that those theories can all be obtained from linear combinations of Lagrangians made by multiplying a particular form of the Galileon Lagrangian by an arbitrary scalar function of the scalar field and its first derivatives. We also obtain curved space-time extensions of those theories which have second-order field equations for both the metric and the scalar field. This provides the most general extension, under the condition that field equations stay second order, of k-essence, Galileons, k-Mouflage as well as of the kinetically braided scalars. It also gives the most general action for a possible scalar classicalizer with second-order field equations. We discuss the relation between our construction and the Euler hierarchies of Fairlie et al. showing, in particular, that Euler hierarchies allow one to obtain the most general theory when the latter is shift symmetric. As a simple application of our formalism, we give the covariantized version of the conformal Galileon.
1,157 citations
TL;DR: In this article, the authors discuss aspects of global and gauged symmetries in quantum field theory and quantum gravity, focusing on discrete gauge symmetsries, and show that all continuous and continuous gauge symmetry are compact and all charges allowed by Dirac quantization are present in the spectrum.
Abstract: We discuss aspects of global and gauged symmetries in quantum field theory and quantum gravity, focusing on discrete gauge symmetries. An effective Lagrangian description of Zp gauge theories shows that they are associated with an emergent Zp one-form (KalbRamond) gauge symmetry. This understanding leads us to uncover new observables and new phenomena in nonlinear σ-models. It also allows us to expand on Polchinski’s classification of cosmic strings. We argue that in models of quantum gravity, there are no global symmetries, all continuous gauge symmetries are compact, and all charges allowed by Dirac quantization are present in the spectrum. These conjectures are not new, but we present them from a streamlined and unified perspective. Finally, our discussion about string charges and symmetries leads to a more physical and more complete understanding of recently found consistency conditions of supergravity.
953 citations
TL;DR: In this paper, the first law of thermodynamics for black holes is defined for a wide variety of rotating asymptotically anti-de Sitter (AdS) spacetimes, using the Smarr relation.
Abstract: In a theory where the cosmological constant $\ensuremath{\Lambda}$ or the gauge coupling constant $g$ arises as the vacuum expectation value, its variation should be included in the first law of thermodynamics for black holes. This becomes $dE=TdS+{\ensuremath{\Omega}}_{i}d{J}_{i}+{\ensuremath{\Phi}}_{\ensuremath{\alpha}}d{Q}_{\ensuremath{\alpha}}+\ensuremath{\Theta}d\ensuremath{\Lambda}$, where $E$ is now the enthalpy of the spacetime, and $\ensuremath{\Theta}$, the thermodynamic conjugate of $\ensuremath{\Lambda}$, is proportional to an effective volume $V=\ensuremath{-}\frac{16\ensuremath{\pi}\ensuremath{\Theta}}{D\ensuremath{-}2}$ ``inside the event horizon.'' Here we calculate $\ensuremath{\Theta}$ and $V$ for a wide variety of $D$-dimensional charged rotating asymptotically anti-de Sitter (AdS) black hole spacetimes, using the first law or the Smarr relation. We compare our expressions with those obtained by implementing a suggestion of Kastor, Ray, and Traschen, involving Komar integrals and Killing potentials, which we construct from conformal Killing-Yano tensors. We conjecture that the volume $V$ and the horizon area $A$ satisfy the inequality $R\ensuremath{\equiv}\phantom{\rule{0ex}{0ex}}((D\ensuremath{-}1)V/{\mathcal{A}}_{D\ensuremath{-}2}{)}^{1/(D\ensuremath{-}1)}({\mathcal{A}}_{D\ensuremath{-}2}/A{)}^{1/(D\ensuremath{-}2)}\ensuremath{\ge}1$, where ${\mathcal{A}}_{D\ensuremath{-}2}$ is the volume of the unit ($D\ensuremath{-}2$) sphere, and we show that this is obeyed for a wide variety of black holes, and saturated for Schwarzschild-AdS. Intriguingly, this inequality is the ``inverse'' of the isoperimetric inequality for a volume $V$ in Euclidean ($D\ensuremath{-}1$) space bounded by a surface of area $A$, for which $R\ensuremath{\le}1$. Our conjectured reverse isoperimetric inequality can be interpreted as the statement that the entropy inside a horizon of a given ''volume'' $V$ is maximized for Schwarzschild-AdS. The thermodynamic definition of $V$ requires a cosmological constant (or gauge coupling constant). However, except in seven dimensions, a smooth limit exists where $\ensuremath{\Lambda}$ or $g$ goes to zero, providing a definition of $V$ even for asymptotically flat black holes.
752 citations
TL;DR: In particular, when the operator is marginal in the IR CFT, the corresponding spectral function is precisely of the ''marginal Fermi liquid'' form, postulated to describe the optimally doped cuprates as discussed by the authors.
Abstract: Gravity solutions dual to $d$-dimensional field theories at finite charge density have a near-horizon region, which is ${\mathrm{AdS}}_{2}\ifmmode\times\else\texttimes\fi{}{\mathbb{R}}^{d\ensuremath{-}1}$. The scale invariance of the ${\mathrm{AdS}}_{2}$ region implies that at low energies the dual field theory exhibits emergent quantum critical behavior controlled by a ($0+1$)-dimensional conformal field theories (CFT). This interpretation sheds light on recently-discovered holographic descriptions of Fermi surfaces, allowing an analytic understanding of their low-energy excitations. For example, the scaling behavior near the Fermi surfaces is determined by conformal dimensions in the emergent IR CFT. In particular, when the operator is marginal in the IR CFT, the corresponding spectral function is precisely of the ``marginal Fermi liquid'' form, postulated to describe the optimally doped cuprates.
738 citations
TL;DR: In this paper, the construction of a Monte Carlo generator for high energy hadronic and nuclear collisions is discussed in detail, taking into consideration enhanced Pomeron diagrams which are resummed to all orders in the triple-Pomeron coupling.
Abstract: The construction of a Monte Carlo generator for high energy hadronic and nuclear collisions is discussed in detail. Interactions are treated in the framework of the Reggeon Field Theory, taking into consideration enhanced Pomeron diagrams which are resummed to all orders in the triple-Pomeron coupling. Soft and “semihard” contributions to the underlying parton dynamics are accounted for within the “semihard Pomeron” approach. The structure of cut enhanced diagrams is analyzed; they are regrouped into a number of subclasses characterized by positively-defined contributions which define partial weights for various “macro-configurations” of hadronic final states. An iterative procedure for a Monte Carlo generation of the structure of final states is described. The model results for hadronic cross sections and for particle production are compared to experimental data.
711 citations
TL;DR: In this paper, a duality between the 2d conformal field theories and higher spin theories on the large $N$ 't Hooft limit was proposed. But the duality was not proved for the Singlet sector of large vector models.
Abstract: We propose a duality between the 2d ${\mathcal{W}}_{N}$ minimal models in the large $N$ 't Hooft limit, and a family of higher spin theories on ${\mathrm{AdS}}_{3}$. The 2d conformal field theories (CFTs) can be described as Wess-Zumino-Witten coset models, and include, for $N=2$, the usual Virasoro unitary series. The dual bulk theory contains, in addition to the massless higher spin fields, two complex scalars (of equal mass). The mass is directly related to the 't Hooft coupling constant of the dual CFT. We give convincing evidence that the spectra of the two theories match precisely for all values of the 't Hooft coupling. We also show that the renormalization group flows in the 2d CFT agree exactly with the usual AdS/CFT prediction of the gravity theory. Our proposal is in many ways analogous to the Klebanov-Polyakov conjecture for an ${\mathrm{AdS}}_{4}$ dual for the singlet sector of large $N$ vector models.
687 citations
TL;DR: In this article, a new class of non-Fermi liquids in (2+1)-dimensions were identified via the response functions of composite fermionic operators in a class of strongly interacting quantum field theories at finite density, computed using the AdS/CFT correspondence.
Abstract: We report on a potentially new class of non-Fermi liquids in (2+1)-dimensions. They are identified via the response functions of composite fermionic operators in a class of strongly interacting quantum field theories at finite density, computed using the AdS/CFT correspondence. We find strong evidence of Fermi surfaces: gapless fermionic excitations at discrete shells in momentum space. The spectral weight exhibits novel phenomena, including particle-hole asymmetry, discrete scale invariance, and scaling behavior consistent with that of a critical Fermi surface postulated by Senthil.
670 citations
TL;DR: In this article, the authors presented the resummation of collinear and soft-gluon corrections to single top quark production in the $t$ channel at next-to-next to-leading logarithm accuracy using two-loop soft anomalous dimensions.
Abstract: I present the resummation of collinear and soft-gluon corrections to single top quark production in the $t$ channel at next-to-next-to-leading logarithm accuracy using two-loop soft anomalous dimensions. The expansion of the resummed cross section yields approximate next-to-next-to-leading-order cross sections. Numerical results for $t$-channel single top quark (or single antitop) production at the Tevatron and the LHC are presented, including the dependence of the cross sections on the top quark mass and the uncertainties from scale variation and parton distributions. Combined results for all single top quark production channels are also given.
617 citations
TL;DR: In this paper, the morphology and spectrum of the gamma ray emission from the center of the Milky Way were studied using the Fermi Gamma Ray Space Telescope (FGSST) and the recently available Pass 7 ultraclean event class.
Abstract: The region surrounding the center of the Milky Way is both astrophysically rich and complex, and is predicted to contain very high densities of dark matter. Utilizing three years of data from the Fermi Gamma Ray Space Telescope (and the recently available Pass 7 ultraclean event class), we study the morphology and spectrum of the gamma ray emission from this region and find evidence of a spatially extended component which peaks at energies between 300 MeV and 10 GeV. We compare our results to those reported by other groups and find good agreement. The extended emission could potentially originate from either the annihilations of dark matter particles in the inner galaxy, or from the collisions of high energy protons that are accelerated by the Milky Way's supermassive black hole with gas. If interpreted as dark matter annihilation products, the emission spectrum favors dark matter particles with a mass in the range of 7-12 GeV (if annihilating dominantly to leptons) or 25-45 GeV (if annihilating dominantly to hadronic final states). The intensity of the emission corresponds to a dark matter annihilation cross section consistent with that required to generate the observed cosmological abundance in the early universe (sigma v ~ 3 x 10^-26 cm^3/s). We also present conservative limits on the dark matter annihilation cross section which are at least as stringent as those derived from other observations.
TL;DR: In this paper, the observable number of sources per solid angle and redshift to the underlying proper source density and velocity, background evolution, and line-of-sight potentials were derived.
Abstract: We relate the observable number of sources per solid angle and redshift to the underlying proper source density and velocity, background evolution, and line-of-sight potentials. We give an exact result in the case of linearized perturbations assuming general relativity. This consistently includes contributions of the source density perturbations and redshift distortions, magnification, radial displacement, and various additional linear terms that are small on subhorizon scales. In addition, we calculate the effect on observed luminosities and hence, the result for sources observed as a function of flux, including magnification bias and radial-displacement effects. We give the corresponding linear result for a magnitude-limited survey at low redshift, and discuss the angular power spectrum of the total count distribution. We also calculate the cross correlation with the CMB polarization and temperature including Doppler source terms, magnification, redshift distortions, and other velocity effects for the sources, and discuss why the contribution of redshift distortions is generally small. Finally, we relate the result for source number counts to that for the brightness of line radiation, for example, 21 cm radiation, from the sources.
TL;DR: The existence of light axions, an Axiverse, is evidence for the extra dimensions of string theory as discussed by the authors, and it has been suggested that the axion cloud can be observed directly either through precision mapping of the near-horizon geometry or through gravitational waves coming from the bosenova explosion, as well as axion transitions and annihilations in the gravitational atom.
Abstract: It has recently been suggested that the presence of a plenitude of light axions, an Axiverse, is evidence for the extra dimensions of string theory. We discuss the observational consequences of these axions on astrophysical black holes through the Penrose superradiance process. When an axion Compton wavelength is comparable to the size of a black hole, the axion binds to the black hole ``nucleus'' forming a gravitational atom in the sky. The occupation number of superradiant atomic levels, fed by the energy and angular momentum of the black hole, grows exponentially. The black hole spins down and an axion Bose-Einstein condensate cloud forms around it. When the attractive axion self-interactions become stronger than the gravitational binding energy, the axion cloud collapses, a phenomenon known in condensed matter physics as ``bosenova''. The existence of axions is first diagnosed by gaps in the mass vs spin plot of astrophysical black holes. For young black holes the allowed values of spin are quantized, giving rise to ``Regge trajectories'' inside the gap region. The axion cloud can also be observed directly either through precision mapping of the near-horizon geometry or through gravitational waves coming from the bosenova explosion, as well as axion transitions and annihilations in the gravitational atom. Our estimates suggest that these signals are detectable in upcoming experiments, such as Advanced LIGO, AGIS, and LISA. Current black hole spin measurements imply an upper bound on the QCD axion decay constant of $2\ifmmode\times\else\texttimes\fi{}{10}^{17}\text{ }\text{ }\mathrm{GeV}$, while Advanced LIGO can detect signals from a QCD axion cloud with a decay constant as low as the GUT scale. We finally discuss the possibility of observing the $\ensuremath{\gamma}$-rays associated with the bosenova explosion and, perhaps, the radio waves from axion-to-photon conversion for the QCD axion.
TL;DR: In this article, it was shown that the Lagrangians are algebraic functions of the usual teleparallel Lagrangian and the action and the field equations are not invariant under local Lorentz transformations.
Abstract: We show that in theories of generalized teleparallel gravity, whose Lagrangians are algebraic functions of the usual teleparallel Lagrangian, the action and the field equations are not invariant under local Lorentz transformations. We also argue that these theories appear to have extra degrees of freedom with respect to general relativity. The usual teleparallel Lagrangian, which has been extensively studied and leads to a theory dynamically equivalent to general relativity, is an exception. Both of these facts appear to have been overlooked in the recent literature on f(T) gravity, but are crucial for assessing the viability of these theories as alternative explanations for the acceleration of the Universe.
TL;DR: In this paper, the authors compute the quantity which is truly measured in a large galaxy survey, taking into account the effects coming from the fact that we actually observe galaxy redshifts and sky positions and not true spatial positions.
Abstract: In this paper we compute the quantity which is truly measured in a large galaxy survey. We take into account the effects coming from the fact that we actually observe galaxy redshifts and sky positions and not true spatial positions. Our calculations are done within linear perturbation theory for both the metric and the source velocities but they can be used for nonlinear matter power spectra. We shall see that the complications due to the fact that we only observe on our background light cone, and that we do not truly know the distance of the observed galaxy but only its redshift, not only cause an additional difficulty, but provide even more a new opportunity for future galaxy surveys.
TL;DR: In this article, the cosmological perturbations in gravity were investigated using a diagonal vierbein, and the corresponding dispersion relation was derived to obtain a theory free of instabilities.
Abstract: We investigate the cosmological perturbations in $f(T)$ gravity. Examining the pure gravitational perturbations in the scalar sector using a diagonal vierbein, we extract the corresponding dispersion relation, which provides a constraint on the $f(T)$ Ans\"atze that lead to a theory free of instabilities. Additionally, upon inclusion of the matter perturbations, we derive the fully perturbed equations of motion, and we study the growth of matter overdensities. We show that $f(T)$ gravity with $f(T)$ constant coincides with General Relativity, both at the background as well as at the first-order perturbation level. Applying our formalism to the power-law model we find that on large subhorizon scales ($\mathcal{O}(100\text{ }\text{ }\mathrm{Mpc})$ or larger), the evolution of matter overdensity will differ from $\ensuremath{\Lambda}\mathrm{CDM}$ cosmology. Finally, examining the linear perturbations of the vector and tensor sectors, we find that (for the standard choice of vierbein) $f(T)$ gravity is free of massive gravitons.
TL;DR: In this article, an electron antineutrino mass has been measured in tritium decay in the Troitsk $\ensuremath{
u}$-mass experiment, and the whole data set acquired from 1994 to 2004 was reanalyzed.
Abstract: An electron antineutrino mass has been measured in tritium $\ensuremath{\beta}$ decay in the Troitsk $\ensuremath{
u}$-mass experiment. The setup consists of a windowless gaseous tritium source and an electrostatic electron spectrometer. The whole data set acquired from 1994 to 2004 was reanalyzed. A thorough selection of data with the reliable experimental conditions has been performed. We checked every known systematic effect and obtained the following experimental estimate for neutrino mass squared ${m}_{\ensuremath{
u}}^{2}=\ensuremath{-}0.67\ifmmode\pm\else\textpm\fi{}2.53\text{ }\text{ }{\mathrm{eV}}^{2}$. This gives an experimental upper sensitivity limit of ${m}_{\ensuremath{
u}}l2.2\text{ }\text{ }\mathrm{eV}$, 95% C.L. and upper limit estimates ${m}_{\ensuremath{
u}}l2.12\text{ }\text{ }\mathrm{eV}$, 95% C.L. for Bayesian statistics and ${m}_{\ensuremath{
u}}l2.05\text{ }\text{ }\mathrm{eV}$, 95% C.L. for the Feldman and Cousins approach.
TL;DR: In this paper, a generalized uncertainty principle (GUP) consistent with string theory, black hole physics, and doubly special relativity theories was proposed to predict quantum gravity corrections to various quantum phenomena such as Lamb shift, simple harmonic oscillator, Landau levels, and tunneling current.
Abstract: Attempts to formulate a quantum theory of gravitation are collectively known as quantum gravity Various approaches to quantum gravity such as string theory and loop quantum gravity, as well as black hole physics and doubly special relativity theories predict a minimum measurable length, or a maximum observable momentum, and related modifications of the Heisenberg Uncertainty Principle to a so-called generalized uncertainty principle (GUP) We have proposed a GUP consistent with string theory, black hole physics, and doubly special relativity theories and have showed that this modifies all quantum mechanical Hamiltonians When applied to an elementary particle, it suggests that the space that confines it must be quantized, and in fact that all measurable lengths are quantized in units of a fundamental length (which can be the Planck length) On the one hand, this may signal the breakdown of the spacetime continuum picture near that scale, and on the other hand, it can predict an upper bound on the quantum gravity parameter in the GUP, from current observations Furthermore, such fundamental discreteness of space may have observable consequences at length scales much larger than the Planck scale Because this influences all the quantum Hamiltonians in an universal way, it predicts quantum gravity corrections to various quantum phenomena Therefore, in the present work we compute these corrections to the Lamb shift, simple harmonic oscillator, Landau levels, and the tunneling current in a scanning tunneling microscope
TL;DR: In this paper, the authors used the virial theorem to infer the average mass of galaxies within the Coma cluster, which is a value much larger than the mass of luminous material.
Abstract: Several recent astrophysical observations of distant type Ia supernovae have revealed that the content of the universe is made of about 70% of dark energy, 25% of dark matter and 5% of baryonic (visible) matter [1]. Thus, the overwhelming preponderance of matter and energy in the universe is believed to be dark i.e. unobservable by telescopes. The dark energy is responsible for the accelerated expansion of the universe. Its origin is mysterious and presumably related to the cosmological constant. Dark energy is usually interpreted as a vacuum energy and it behaves like a fluid with negative pressure. Dark matter also is mysterious. The suggestion that dark matter may constitute a large part of the universe was raised by Zwicky [2] in 1933. Using the virial theorem to infer the average mass of galaxies within the Coma cluster, he obtained a value much larger than the mass of luminous material. He realized therefore that some mass was “missing” in order to account for observations. This missing mass problem was confirmed later by accurate measurements of rotation curves of disc galaxies [3, 4]. The rotation curves of neutral hydrogen clouds in spiral galaxies measured from the Doppler effect are found to be roughly flat (instead of Keplerian) with a typical rotational velocity v∞ ∼ 200km/s up to the maximum observed radius of about 50 kpc. This mass profile is much more extended than the distribution of starlight which typically converges within ∼ 10 kpc. This implies that galaxies are surrounded by an extended halo of dark matter whose mass M(r) = rv 2/G increases linearly with radius [56]. This can be conveniently modeled by an isothermal self-gravitating gas the density of which scales asymptotically as r −2 [6].
University of Tokyo1, Kyoto University2, University of California, Irvine3, Autonomous University of Madrid4, Boston University5, University of Wisconsin-Madison6, Brookhaven National Laboratory7, California State University, Dominguez Hills8, Chonnam National University9, Duke University10, Fukuoka Institute of Technology11, Gifu University12, Kanagawa University13, Kobe University14, Miyagi University of Education15, Nagoya University16, Stony Brook University17, Niigata University18, Okayama University19, Osaka University20, Seoul National University21, Shizuoka University22, Sungkyunkwan University23, Tokai University24, Tsinghua University25, University of Warsaw26, University of Washington27, University of Minnesota28
TL;DR: The results of the third phase of the Super-Kamiokande solar neutrino measurement are presented and compared to the first and second phase results in this article, where improved detector calibrations, a full detector simulation, and improved analysis methods are estimated to be approximately 2.1%, which is about two thirds of the systematic uncertainty for the first phase.
Abstract: The results of the third phase of the Super-Kamiokande solar neutrino measurement are presented and compared to the first and second phase results. With improved detector calibrations, a full detector simulation, and improved analysis methods, the systematic uncertainty on the total neutrino flux is estimated to be $\ifmmode\pm\else\textpm\fi{}2.1%$, which is about two thirds of the systematic uncertainty for the first phase of Super-Kamiokande. The observed $^{8}\mathrm{B}$ solar flux in the 5.0 to 20 MeV total electron energy region is $2.32\ifmmode\pm\else\textpm\fi{}0.04(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.05(\mathrm{sys})\ifmmode\times\else\texttimes\fi{}{10}^{6}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}2}\text{ }{\mathrm{sec}}^{\ensuremath{-}1}$ under the assumption of pure electron-flavor content, in agreement with previous measurements. A combined oscillation analysis is carried out using SK-I, II, and III data, and the results are also combined with the results of other solar neutrino experiments. The best-fit oscillation parameters are obtained to be ${sin }^{2}{\ensuremath{\theta}}_{12}={0.30}_{\ensuremath{-}0.01}^{+0.02}({tan }^{2}{\ensuremath{\theta}}_{12}={0.42}_{\ensuremath{-}0.02}^{+0.04})$ and $\ensuremath{\Delta}{m}_{21}^{2}={6.2}_{\ensuremath{-}1.9}^{+1.1}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\text{ }\text{ }{\mathrm{eV}}^{2}$. Combined with KamLAND results, the best-fit oscillation parameters are found to be ${sin }^{2}{\ensuremath{\theta}}_{12}=0.31\ifmmode\pm\else\textpm\fi{}0.01({tan }^{2}{\ensuremath{\theta}}_{12}=0.44\ifmmode\pm\else\textpm\fi{}0.03)$ and $\ensuremath{\Delta}{m}_{21}^{2}=7.6\ifmmode\pm\else\textpm\fi{}0.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\text{ }\text{ }{\mathrm{eV}}^{2}$. The $^{8}\mathrm{B}$ neutrino flux obtained from global solar neutrino experiments is $5.3\ifmmode\pm\else\textpm\fi{}0.2(\mathrm{stat}+\mathrm{sys})\ifmmode\times\else\texttimes\fi{}{10}^{6}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}2}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$, while the $^{8}\mathrm{B}$ flux becomes $5.1\ifmmode\pm\else\textpm\fi{}0.1(\mathrm{stat}+\mathrm{sys})\ifmmode\times\else\texttimes\fi{}{10}^{6}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}2}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$ by adding KamLAND results. In a three-flavor analysis combining all solar neutrino experiments, the upper limit of ${sin }^{2}{\ensuremath{\theta}}_{13}$ is 0.060 at 95% C.L.. After combination with KamLAND results, the upper limit of ${sin }^{2}{\ensuremath{\theta}}_{13}$ is found to be 0.059 at 95% C.L.
TL;DR: In this article, the authors propose a deepening of the relativity principle according to which the invariant arena for nonquantum physics is a phase space rather than spacetime, and they also discuss a natural set of physical hypotheses which singles out the cases of energy-momentum space with a metric compatible connection and constant curvature.
Abstract: We propose a deepening of the relativity principle according to which the invariant arena for nonquantum physics is a phase space rather than spacetime. Descriptions of particles propagating and interacting in spacetimes are constructed by observers, but different observers, separated from each other by translations, construct different spacetime projections from the invariant phase space. Nonetheless, all observers agree that interactions are local in the spacetime coordinates constructed by observers local to them. This framework, in which absolute locality is replaced by relative locality, results from deforming energy-momentum space, just as the passage from absolute to relative simultaneity results from deforming the linear addition of velocities. Different aspects of energy-momentum space geometry, such as its curvature, torsion and nonmetricity, are reflected in different kinds of deformations of the energy-momentum conservation laws. These are in principle all measurable by appropriate experiments. We also discuss a natural set of physical hypotheses which singles out the cases of energy-momentum space with a metric compatible connection and constant curvature.
TL;DR: In this article, the authors studied a class of multimatrix integrals describing supersymmetric Chern-Simons gauge theories, and they presented a simple method that allows them to evaluate the eigenvalue densities and the free energies in the large $N$ limit.
Abstract: Localization methods reduce the path integrals in $\mathcal{N}\ensuremath{\ge}2$ supersymmetric Chern-Simons gauge theories on ${S}^{3}$ to multimatrix integrals. A recent evaluation of such a two-matrix integral for the $\mathcal{N}=6$ superconformal $U(N)\ifmmode\times\else\texttimes\fi{}U(N)$ Aharony-Bergman-Jafferis-Maldacena theory produced detailed agreement with the AdS/CFT correspondence, explaining, in particular, the ${N}^{3/2}$ scaling of the free energy. We study a class of $p$-matrix integrals describing $\mathcal{N}=3$ superconformal $U(N{)}^{p}$ Chern-Simons gauge theories. We present a simple method that allows us to evaluate the eigenvalue densities and the free energies in the large $N$ limit keeping the Chern-Simons levels ${k}_{i}$ fixed. The dual M-theory backgrounds are ${\mathrm{AdS}}_{4}\ifmmode\times\else\texttimes\fi{}Y$, where $Y$ are seven-dimensional tri-Sasaki Einstein spaces specified by the ${k}_{i}$. The gravitational free energy scales inversely with the square root of the volume of $Y$. We find a general formula for the $p$-matrix free energies that agrees with the available results for volumes of the tri-Sasaki Einstein spaces $Y$, thus providing a thorough test of the corresponding ${\mathrm{AdS}}_{4}/{\mathrm{CFT}}_{3}$ dualities. This formula is consistent with the Seiberg duality conjectured for Chern-Simons gauge theories.
TL;DR: In this article, the geometry of detector configurations preferable for identifying the binary signals was discussed and the minimum signal-to-noise ratios of the binaries for several static detector configurations that are characterized by adjustable geometrical parameters, and determined the optimal values for these parameters.
Abstract: The primary target for the planned space-borne gravitational wave interferometers DECIGO/BBO (Decihertz Interferometer Gravitational Wave Observatory/Big Bang Observer) is a primordial gravitational wave background. However there exist astrophysical foregrounds, and among them, gravitational waves from neutron-star (NS) binaries are the solid and strong component that must be identified and subtracted. In this paper, we discuss the geometry of detector configurations preferable for identifying the NS/NS binary signals. As a first step, we analytically estimate the minimum signal-to-noise ratios of the binaries for several static detector configurations that are characterized by adjustable geometrical parameters, and determine the optimal values for these parameters. Next we perform numerical simulations to take into account the effect of detector motions, and find reasonable agreements with the analytical results. We show that, with the standard network formed by 4 units of triangle detectors, the proposed BBO sensitivity would be sufficient in receiving gravitational waves from all the NS/NS binaries at $z\ensuremath{\le}5$ with signal-to-noise ratios higher than 25. We also discuss the minimum sensitivity of DECIGO required for the foreground identification.
TL;DR: In this paper, the authors used LEP data on monophoton events with large missing energy to constrain the coupling of dark matter to electrons, which is complementary to and competitive with limits on dark matter annihilation and WIMP-nucleon scattering from indirect and direct searches.
Abstract: Dark matter pair production at high energy colliders may leave observable signatures in the energy and momentum spectra of the objects recoiling against the dark matter. We use LEP data on monophoton events with large missing energy to constrain the coupling of dark matter to electrons. Within a large class of models, our limits are complementary to and competitive with limits on dark matter annihilation and on WIMP-nucleon scattering from indirect and direct searches. Our limits, however, do not suffer from systematic and astrophysical uncertainties associated with direct and indirect limits. For example, we are able to rule out light ($\ensuremath{\lesssim}10\text{ }\text{ }\mathrm{GeV}$) thermal relic dark matter with universal couplings exclusively to charged leptons. In addition, for dark matter mass below about 80 GeV, LEP limits are stronger than Fermi constraints on annihilation into charged leptons in dwarf spheroidal galaxies. Within its kinematic reach, LEP also provides the strongest constraints on the spin-dependent direct detection cross section in models with universal couplings to both quarks and leptons. In such models the strongest limit is also set on spin-independent scattering for dark matter masses below $\ensuremath{\sim}4\text{ }\text{ }\mathrm{GeV}$. Throughout our discussion, we consider both low energy effective theories of dark matter, as well as several motivated renormalizable scenarios involving light mediators.
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TL;DR: The cosmological solutions of a recently proposed extension of General Relativity with a Lorentz-invariant mass term were explored in this article, where the same constraint that removes the Boulware-Deser ghost in this theory also prohibits the existence of homogeneous and isotropic cosmologies.
Abstract: We explore the cosmological solutions of a recently proposed extension of General Relativity with a Lorentz-invariant mass term We show that the same constraint that removes the Boulware-Deser ghost in this theory also prohibits the existence of homogeneous and isotropic cosmological solutions Nevertheless, within domains of the size of inverse graviton mass we find approximately homogeneous and isotropic solutions that can well describe the past and present of the Universe At energy densities above a certain crossover value, these solutions approximate the standard FRW evolution with great accuracy As the Universe evolves and density drops below the crossover value the inhomogeneities become more and more pronounced In the low density regime each domain of the size of the inverse graviton mass has essentially non-FRW cosmology This scenario imposes an upper bound on the graviton mass, which we roughly estimate to be an order of magnitude below the present-day value of the Hubble parameter The bound becomes especially restrictive if one utilizes an exact self-accelerated solution that this theory offers Although the above are robust predictions of massive gravity with an explicit mass term, we point out that if the mass parameter emerges from some additional scalar field condensation, the constraint no longer forbids the homogeneous and isotropic cosmologies In the latter case, there will exist an extra light scalar field at cosmological scales, which is screened by the Vainshtein mechanism at shorter distances
TL;DR: In this paper, the authors improved the description of π π scattering data by imposing additional requirements on previous fits, in the form of once-subtracted Roy-like equations, while extending their analysis up to 1100 MeV.
Abstract: We improve our description of π π scattering data by imposing additional requirements on our previous fits, in the form of once-subtracted Roy-like equations, while extending our analysis up to 1100 MeV. We provide simple and ready to use parametrizations of the amplitude. In addition, we present a detailed description and derivation of these once-subtracted dispersion relations that, in the 450 to 1100 MeV region, provide an additional constraint which is much stronger than our previous requirements of forward dispersion relations and standard Roy equations. The ensuing constrained amplitudes describe the existing data with rather small uncertainties in the whole region from threshold up to 1100 MeV, while satisfying very stringent dispersive constraints. For the S0 wave, this requires an improved matching of the low and high energy parametrizations. Also for this wave we have considered the latest low energy K_(l4) decay results, including their isospin violation correction, and we have removed some controversial data points. These changes on the data translate into better determinations of threshold and subthreshold parameters which remove almost alldisagreement with previous chiral perturbation theory and Roy equation calculations below 800 MeV. Finally, our results favor the dip structure of the S0 inelasticity around the controversial 1000 MeV region.
TL;DR: In this article, the Weizsacker-Williams distribution and dipole gluon distribution were investigated for dijet production in the small-x limit and large-Nc limit, respectively.
Abstract: We systematically study dijet production in various processes in the small-x limit and establish an effective kt-factorization for hard processes in a system with dilute probes scattering on a dense target. In the large-Nc limit, the unintegrated gluon distributions involved in different processes are shown to be related to two widely proposed ones: the Weizsacker-Williams gluon distribution and the dipole gluon distribution.
TL;DR: In this article, a new measurement of the inclusive forward-backward t{bar t} production asymmetry and its rapidity and mass dependence was presented, with data corresponding to an integrated luminosity of 5.3 fb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV.
Abstract: We present a new measurement of the inclusive forward-backward t{bar t} production asymmetry and its rapidity and mass dependence. The measurements are performed with data corresponding to an integrated luminosity of 5.3 fb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV, recorded with the CDF II Detector at the Fermilab Tevatron. Significant inclusive asymmetries are observed in both the laboratory frame and the t{bar t} rest frame, and in both cases are found to be consistent with CP conservation under interchange of t and {bar t}. In the t{bar t} rest frame, the asymmetry is observed to increase with the t{bar t} rapidity difference, {Delta}y, and with the invariant mass M{sub t{bar t}} of the t{bar t} system. Fully corrected parton-level asymmetries are derived in two regions of each variable, and the asymmetry is found to be most significant at large {Delta}y and M{sub t{bar t}}. For M{sub t{bar t}} {ge} 450 GeV/c{sup 2}, the parton-level asymmetry in the t{bar t} rest frame is A{sup t{bar t}} = 0.475 {+-} 0.114 compared to a next-to-leading order QCD prediction of 0.088 {+-} 0.013.
TL;DR: In this paper, the authors assess the current phenomenological status of transverse momentum dependent (TMD) parton distribution functions (PDFs) and study the effect of consistently including perturbative QCD (pQCD) evolution.
Abstract: We assess the current phenomenological status of transverse momentum dependent (TMD) parton distribution functions (PDFs) and fragmentation functions (FFs) and study the effect of consistently including perturbative QCD (pQCD) evolution. Our goal is to initiate the process of establishing reliable, QCD-evolved parametrizations for the TMD PDFs and TMD FFs that can be used both to test TMD factorization and to search for evidence of the breakdown of TMD factorization that is expected for certain processes. In this article, we focus on spin-independent processes because they provide the simplest illustration of the basic steps and can already be used in direct tests of TMD factorization. Our calculations are based on the Collins-Soper-Sterman (CSS) formalism, supplemented by recent theoretical developments which have clarified the precise definitions of the TMD PDFs and TMD FFs needed for a valid TMD-factorization theorem. Starting with these definitions, we numerically generate evolved TMD PDFs and TMD FFs using as input existing parametrizations for the collinear PDFs, collinear FFs, nonperturbative factors in the CSS factorization formalism, and recent fixed-scale fits. We confirm that evolution has important consequences, both qualitatively and quantitatively, and argue that it should be included in future phenomenological studies of TMD functions. Our analysis is also suggestive of extensions to processes that involve spin-dependent functions such as the Boer-Mulders, Sivers, or Collins functions, which we intend to pursue in future publications. At our website [http://projects.hepforge.org/tmd/], we have made available the tables and calculations needed to obtain the TMD parametrizations presented herein.
TL;DR: In this article, the Nucleon and Delta excited state spectra on dynamical anisotropic clover lattices were calculated and the first time this has been achieved in a lattice calculation.
Abstract: We present a calculation of the Nucleon and Delta excited state spectra on dynamical anisotropic clover lattices. A method for operator construction is introduced that allows for the reliable identification of the continuum spins of baryon states, overcoming the reduced symmetry of the cubic lattice. Using this method, we are able to determine a spectrum of single-particle states for spins up to and including $J=\frac{7}{2}$, of both parities, the first time this has been achieved in a lattice calculation. We find a spectrum of states identifiable as admixtures of $SU(6)\ensuremath{\bigotimes}O(3)$ representations and a counting of levels that is consistent with the nonrelativistic $qqq$ constituent quark model. This dense spectrum is incompatible with quark-diquark model solutions to the ``missing resonance problem'' and shows no signs of parity doubling of states.