A simple way of explaining dark matter without modifying known Standard Model physics is to require the existence of a hidden (dark) sector, which interacts with the visible one predominantly via gravity. We consider a hidden sector containing two stable particles charged under an unbroken $U(1{)}^{\prime }$ gauge symmetry, hence featuring dissipative interactions. The massless gauge field associated with this symmetry, the dark photon, can interact via kinetic mixing with the ordinary photon. In fact, such an interaction of strength $\epsilon \sim {10}^{-9}$ appears to be necessary in order to explain galactic structure. We calculate the effect of this new physics on big bang nucleosynthesis and its contribution to the relativistic energy density at hydrogen recombination. We then examine the process of dark recombination, during which neutral dark states are formed, which is important for large-scale structure formation. Galactic structure is considered next, focusing on spiral and irregular galaxies. For these galaxies we modeled the dark matter halo (at the current epoch) as a dissipative plasma of dark matter particles, where the energy lost due to dissipation is compensated by the energy produced from ordinary supernovae (the core-collapse energy is transferred to the hidden sector via kinetic mixing induced processes in the supernova core). We find that such a dynamical halo model can reproduce several observed features of disk galaxies, including the cored density profile and the Tully-Fisher relation. We also discuss how elliptical and dwarf spheroidal galaxies could fit into this picture. Finally, these analyses are combined to set bounds on the parameter space of our model, which can serve as a guideline for future experimental searches.

The effective actions of gauge bosons, fermions, and scalars, which are obtained within the hard-loop approximation, are shown to have unique forms for a whole class of gauge theories including QED, scalar QED, super QED, pure Yang-Mills, QCD, and super Yang-Mills. The universality occurs irrespective of a field content of each theory and of a variety of specific interactions. Consequently, the long-wavelength or semiclassical features of plasma systems governed by these theories such as collective excitations are almost identical. An origin of the universality, which holds within the limits of applicability of the hard-loop approach, is discussed.

We present an exact solution to the Boltzmann equation which describes a system undergoing boost-invariant longitudinal and azimuthally symmetric radial expansion for arbitrary shear viscosity to entropy density ratio. This new solution is constructed by considering the conformal map between Minkowski space and the direct product of three-dimensional de Sitter space with a line. The resulting solution respects $SO(3{)}_q\otimes SO(1,1)\otimes Z_2$ symmetry. We compare the exact kinetic solution with exact solutions of the corresponding macroscopic equations that were obtained from the kinetic theory in ideal and second-order viscous hydrodynamic approximations. The macroscopic solutions are obtained in de Sitter space and are subject to the same symmetries used to obtain the exact kinetic solution.

Understanding the relation between underlying matter distribution and biased tracers such as galaxies or dark matter halos is essential to extract cosmological information from ongoing or future galaxy redshift surveys. At sufficiently large scales such as the baryon acoustic oscillation (BAO) scale, a standard approach for the bias problem on the basis of the perturbation theory (PT) is to assume the “local bias” model in which the density field of biased tracers is deterministically expanded in terms of matter density field at the same position. The higher-order bias parameters are then determined by combining the power spectrum with higher-order statistics such as the bispectrum. As is pointed out by recent studies, however, nonlinear gravitational evolution naturally induces nonlocal bias terms even if initially starting only with purely local bias. As a matter of fact, previous works showed that the second-order nonlocal bias term, which corresponds to the gravitational tidal field, is important to explain the characteristic scale-dependence of the bispectrum. In this paper we extend the nonlocal bias term up to third order, and investigate whether the PT-based model including nonlocal bias terms can simultaneously explain the power spectrum and the bispectrum of simulated halos in $N$-body simulations. The bias renormalization procedure ensures that only one additional term is necessary to be introduced to the power spectrum as a next-to-leading order correction, even if third-order nonlocal bias terms are taken into account. We show that the power spectrum, including density and momentum, and the bispectrum between halo and matter in $N$-body simulations can be simultaneously well explained by the model including up to third-order nonlocal bias terms at $k\lesssim 0.1h/\mathrm{Mpc}$. Also, the results are in a good agreement with theoretical predictions of a simple coevolution picture, although the agreement is not perfect. These trend can be found for a wide range of halo mass, $0.7\lesssim M_{\text{halo}}[10^{13}{M}_{\odot }/h]\lesssim 20$ at various redshifts, $0\le z\le 1$. These demonstrations clearly show a failure of the local bias model even at such large scales, and we conclude that nonlocal bias terms should be consistently included in order to accurately model statistics of halos.

We present a unifying theme relating BPS partition functions and superconformal indices. In the case with complex supersymmetry central charges (as in $\mathcal{N}=2$ in $d=4$ and $\mathcal{N}=(2,2)$ in $d=2$), the known results can be reinterpreted as the statement that the BPS partition functions can be used to compute a specialization of the superconformal indices. We argue that in the case with real central charge in the supersymmetry algebra, as in $\mathcal{N}=1$ in $d=5$ (or the $\mathcal{N}=2$ in $d=3$), the BPS degeneracy captures the full superconformal index. Furthermore, we argue that refined topological strings, which capture five-dimensional (5d) BPS degeneracies of M theory on Calabi-Yau 3-folds, can be used to compute a 5d supersymmetric index including in the sectors with three-dimensional defects for a large class of 5d superconformal theories. Moreover, we provide evidence that distinct Calabi–Yau singularities which are expected to lead to the same Superconformal field theory yield the same index.

We calculate the masses of baryons containing one, two, or three heavy quarks using lattice QCD. We consider all possible combinations of charm and bottom quarks, and compute a total of 36 different states with $J^P={\frac{1}{2}}^{+}$ and $J^P={\frac{3}{2}}^{+}$. We use domain-wall fermions for the up, down, and strange quarks, a relativistic heavy-quark action for the charm quarks, and nonrelativistic QCD for the bottom quarks. Our analysis includes results from two different lattice spacings and seven different pion masses. We perform extrapolations of the baryon masses to the continuum limit and to the physical pion mass using $\mathrm{SU}(4|2)$ heavy-hadron chiral perturbation theory including $1/m_Q$ and finite-volume effects. For the 14 singly heavy baryons that have already been observed, our results agree with the experimental values within the uncertainties. We compare our predictions for the hitherto unobserved states with other lattice calculations and quark-model studies.

The massless Gross-Neveu and chiral Gross-Neveu models are well known examples of integrable quantum field theories in $1+1$ dimensions. We address the question of whether integrability is preserved if one either replaces the four-fermion interaction in fermion-antifermion channels by a dual interaction in fermion-fermion channels, or if one adds such a dual interaction to an existing integrable model. The relativistic Hartree-Fock-Bogoliubov approach is adequate to deal with the large-$N$ limit of such models. In this way, we construct and solve three integrable models with Cooper pairing. We also identify a candidate for a fourth integrable model with maximal kinematic symmetry, the “perfect” Gross-Neveu model. This type of field theories can serve as exactly solvable toy models for color superconductivity in quantum chromodynamics.

We extend the notion of general coordinate invariance to many-body, not necessarily relativistic, systems. As an application, we investigate nonrelativistic general covariance in Galilei-invariant systems. The peculiar transformation rules for the background metric and gauge fields, first introduced by Son and Wingate in 2005 and refined in subsequent works, follow naturally from our framework. Our approach makes it clear that Galilei or Poincaré symmetry is by no means a necessary prerequisite for making the theory invariant under coordinate diffeomorphisms. General covariance merely expresses the freedom to choose spacetime coordinates at will, whereas the true, physical symmetries of the system can be separately implemented as “internal” symmetries within the vielbein formalism. A systematic way to implement such symmetries is provided by the coset construction. We illustrate this point by applying our formalism to nonrelativistic $s$-wave superfluids.

We propose methods and present calculations that can be used to search for evidence of cosmic fields by investigating the parity-violating effects, including parity nonconservation amplitudes and electric dipole moments, that they induce in atoms. The results are used to constrain important fundamental parameters describing the strength of the interaction of various cosmic fields with electrons, protons, and neutrons. Candidates for such fields are dark matter (including axions) and dark energy, as well as several more exotic sources described by standard-model extensions. Calculations of the effects induced by pseudoscalar and pseudovector fields are performed for H, Li, Na, K, Cu, Rb, Ag, Cs, Ba, ${\mathrm{Ba}}^{+}$, Dy, Yb, Au, Tl, Fr, and ${\mathrm{Ra}}^{+}$. Existing parity nonconservation experiments in Cs, Dy, Yb, and Tl are combined with these calculations to directly place limits on the interaction strength between the temporal component, $b_0$, of a static pseudovector cosmic field and the atomic electrons, with the most stringent limit of $|b_0^e|<7\times {10}^{-15}\mathrm{GeV}$, in the laboratory frame of reference, coming from Dy. From a measurement of the nuclear anapole moment of Cs, and a limit on its value for Tl, we also extract limits on the interaction strength between the temporal component of this cosmic field, as well as a related tensor cosmic-field component $d_{00}$, with protons and neutrons. The most stringent limits of $|b_0^p|<4\times {10}^{-8}\mathrm{GeV}$ and $|d_{00}^p|<5\times {10}^{-8}$ for protons and $|b_0^n|<2\times {10}^{-7}\mathrm{GeV}$ and $|d_{00}^n|<2\times {10}^{-7}$ for neutrons (in the laboratory frame) come from the results using Cs. Axions may induce oscillating parity- and time reversal-violating effects in atoms and molecules through the generation of oscillating nuclear magnetic quadrupole and Schiff moments, which arise from $P$- and $T$-odd intranuclear forces and from the electric dipole moments of constituent nucleons. Nuclear spin-independent parity nonconservation effects may be enhanced in diatomic molecules possessing close pairs of opposite-parity levels in the presence of time-dependent interactions.

Many theories beyond the Standard Model contain hidden photons. A light hidden photon will generically couple to the Standard Model through a kinetic mixing term, giving a powerful avenue for detection using “light-shining-through-a-wall”-type transmission experiments with resonant cavities. We demonstrate a parametric enhancement of the signal in such experiments, resulting from transmission of the longitudinal mode of the hidden photon. While previous literature has focused on the production and detection of transverse modes, the longitudinal mode allows a significant improvement in experimental sensitivity. Although optical experiments such as ALPS are unable to take useful advantage of this enhancement, the reach of existing microwave cavity experiments such as CROWS is significantly enhanced beyond their published results. Future microwave cavity experiments, designed with appropriate geometry to take full advantage of the longitudinal mode, will provide a powerful probe of hidden-photon parameter space extending many orders of magnitude beyond current limits, including significant regions where the hidden photon can be dark matter.

Galactic cosmic-ray (CR) transport parameters are usually constrained by the boron-to-carbon ratio. This procedure is generically plagued with degeneracies between the diffusion coefficient and the vertical extent of the Galactic magnetic halo. The latter is of paramount importance for indirect dark matter (DM) searches because it fixes the amount of DM annihilation or decay that contributes to the local antimatter CR flux. These degeneracies could be broken by using secondary radioactive species, but the current data still have large error bars, and this method is extremely sensitive to the very local interstellar medium properties. Here, we propose to use the low-energy CR positrons in the GeV range as another direct constraint on diffusion models. We show that the PAMELA data disfavor small diffusion halo ($L\lesssim 3\mathrm{kpc}$) and large diffusion slope models and exclude the minimal configuration [Maurin et al. Astrophys. J. 555, 585 (2001); Donato et al. Phys. Rev. D 69, 063501 (2004)] widely used in the literature to bracket the uncertainties in the DM signal predictions. This is complementary to indirect constraints (diffuse radio and gamma-ray emissions) and has a strong impact on DM searches. Indeed, this makes the antiproton constraints more robust while enhancing the discovery/exclusion potential of current and future experiments, like AMS-02 and GAPS, especially in the antiproton and antideuteron channels.

We have searched for proton decay via $p\to \nu K^{+}$ using Super-Kamiokande data from April 1996 to February 2013, $260\mathrm{kiloton}·\mathrm{year}$ exposure in total. No evidence for this proton decay mode is found. A lower limit of the proton lifetime is set to $\tau /B(p\to \nu K^{+})>5.9\times 10^{33}$ years at 90% confidence level.

The resonant substructure of $B_s^0\to {\overline{D}}^0{K}^{-}{\pi }^{+}$ decays is studied with the Dalitz plot analysis technique. The study is based on a data sample corresponding to an integrated luminosity of $3.0{\mathrm{fb}}^{-1}$ of $pp$ collision data recorded by LHCb. A structure at $m({\overline{D}}^0{K}^{-})\approx 2.86\mathrm{GeV}/c^2$ is found to be an admixture of spin-1 and spin-3 resonances. The masses and widths of these states and of the $D_{s2}^{*}(2573{)}^{-}$ meson are measured, as are the complex amplitudes and fit fractions for all the ${\overline{D}}^0{K}^{-}$ and $K^{-}{\pi }^{+}$ components included in the amplitude model. In addition, the $D_{s2}^{*}(2573{)}^{-}$ resonance is confirmed to be spin 2.

We perform an extensive survey of nonstandard Higgs decays that are consistent with the 125 GeV Higgs-like resonance. Our aim is to motivate a large set of new experimental analyses on the existing and forthcoming data from the Large Hadron Collider (LHC). The explicit search for exotic Higgs decays presents a largely untapped discovery opportunity for the LHC collaborations, as such decays may be easily missed by other searches. We emphasize that the Higgs is uniquely sensitive to the potential existence of new weakly coupled particles and provide a unified discussion of a large class of both simplified and complete models that give rise to characteristic patterns of exotic Higgs decays. We assess the status of exotic Higgs decays after LHC run I. In many cases we are able to set new nontrivial constraints by reinterpreting existing experimental analyses. We point out that improvements are possible with dedicated analyses and perform some preliminary collider studies. We prioritize the analyses according to their theoretical motivation and their experimental feasibility. This document is accompanied by a Web site that will be continuously updated with further information [http://exotichiggs.physics.sunysb.edu].

This paper explores a novel tractable regime for ultraviolet-complete quantum field theories—the large $N_c$ limit of non-Abelian gauge theories with quarks in high-dimensional representations (scaling with $N_c$ faster than $N_c^2$), such as quarks with “a” fundamental indices with $a\ge 3$. A smooth and nontrivial $N_c$ limit can be obtained if $g^2{N}_c^{a-1}$ is held fixed instead of the standard ’t Hooft coupling $g^2{N}_c$ as $N_c\to \infty$ where $g$ is the gauge coupling. $\mathrm{SU}(N_c)$ gauge theories in $3+1$ dimensions are not asymptotically free at large $N_c$ when they contain quarks in representations for which the dimensions scale faster than $N_c^2$ and hence are not ultraviolet complete. However, in lower space-time dimensions ($2+1$, $1+1$), for any $N_c$, renormalization group flow for such theories always has a stable ultraviolet fixed point at $g=0$; the theory is thus ultraviolet complete. For the case of massless quarks, the theory has an infrared fixed point. For massive quarks, the theory is confining. The confining scale is parametrically of the order $N_c^{\frac{2-a}{4-d}}$ and is driven to zero at large $N_c$ for theories with $a>2$ and $d<4$ where $d$ is the space-time dimension.

Direct detection dark matter experiments looking for WIMP-nucleus elastic scattering will soon be sensitive to an irreducible background from neutrinos which will drastically affect their discovery potential. Here we explore how the neutrino background will affect future ton-scale experiments considering both spin-dependent and spin-independent interactions. We show that combining data from experiments using different targets can improve the dark matter discovery potential due to target complementarity. We find that in the context of spin-dependent interactions, combining results from several targets can greatly enhance the subtraction of the neutrino background for WIMP masses below $10\mathrm{GeV}/c^2$ and therefore probe dark matter models to lower cross sections. In the context of target complementarity, we also explore how one can tune the relative exposures of different target materials to optimize the WIMP discovery potential.

We study $\mathcal{N}=1$ field theories with a $U(1{)}_R$ symmetry on compact four-manifolds $\mathcal{M}$. Supersymmetry requires $\mathcal{M}$ to be a complex manifold. The supersymmetric theory on $\mathcal{M}$ can be described in terms of conventional fields coupled to background supergravity, or in terms of twisted fields adapted to the complex geometry of $\mathcal{M}$. Many properties of the theory that are difficult to see in one formulation are simpler in the other one. We use the twisted description to study the dependence of the partition function $Z_{\mathcal{M}}$ on the geometry of $\mathcal{M}$, as well as coupling constants and background gauge fields, recovering and extending previous results. We also indicate how to generalize our analysis to three-dimensional $\mathcal{N}=2$ theories with a $U(1{)}_R$ symmetry. In this case supersymmetry requires $\mathcal{M}$ to carry a transversely holomorphic foliation, which endows it with a near-perfect analogue of complex geometry. Finally, we present new explicit formulas for the dependence of $Z_{\mathcal{M}}$ on the choice of $U(1{)}_R$ symmetry in four and three dimensions, and illustrate them for complex manifolds diffeomorphic to $S^3\times S^1$, as well as general squashed three-spheres.

The entropic approach to dissociation of bound states immersed in strongly coupled systems is developed. In such systems, the excitations of the bound state are often delocalized and characterized by a large entropy, so that the bound state is strongly entangled with the rest of the statistical system. If this entropy $S$ increases with the separation $r$ between the constituents of the bound state, $S=S(r)$, then the resulting entropic force $F=T$ $\partial S/\partial r$ ($T$ is temperature) can drive the dissociation process. As a specific example, we consider the case of heavy quarkonium in strongly coupled quark-gluon plasma, where lattice QCD indicates a large amount of entropy associated with the heavy quark pair at temperatures $0.9T_c\le T\le 1.5T_c$ ($T_c$ is the deconfinement temperature); this entropy $S(r)$ grows with the interquark distance $r$. We argue that the entropic mechanism results in an anomalously strong quarkonium suppression in the temperature range near $T_c$. This entropic self-destruction may thus explain why the experimentally measured quarkonium nuclear modification factor at RHIC (lower energy density) is smaller than at LHC (higher energy density), possibly resolving the “quarkonium suppression puzzle”—all of the previously known mechanisms of quarkonium dissociation operate more effectively at higher energy densities, and this contradicts the data. Moreover, we find that near $T_c$ the entropic force leads to delocalization of the bound hadron states; we argue that this delocalization may be the mechanism underlying deconfinement.

We describe an alternative approach to the analysis of gravitational-wave backgrounds, based on the formalism used to characterize the polarization of the cosmic microwave background. In contrast to standard analyses, this approach makes no assumptions about the nature of the background and so has the potential to reveal much more about the physical processes that generated it. An arbitrary background can be decomposed into modes whose angular dependence on the sky is given by gradients and curls of spherical harmonics. We derive the pulsar timing overlap reduction functions for the individual modes, which are given by simple combinations of spherical harmonics evaluated at the pulsar locations. We show how these can be used to recover the components of an arbitrary background, giving explicit results for both isotropic and anisotropic uncorrelated backgrounds. We also find that the response of a pulsar timing array to curl modes is identically zero, so half of the gravitational-wave sky will never be observed using pulsar timing, no matter how many pulsars are included in the array. An isotropic, unpolarized and uncorrelated background can be accurately represented using only three modes, and so a search of this type will be only slightly more complicated than the standard cross-correlation search using the Hellings and Downs overlap reduction function. However, by measuring the components of individual modes of the background and checking for consistency with isotropy, this approach has the potential to reveal much more information. Each individual mode on its own describes a background that is correlated between different points on the sky. A measurement of the components that indicates the presence of correlations in the background on large angular scales would suggest startling new physics.

We analyze the feasibility of detecting the polarization of the cosmic microwave background (CMB) caused by scattering of the remote temperature quadrupole by galaxy clusters with forthcoming CMB polarization surveys. For low-redshift clusters, the signal is strongly correlated with the local large-scale temperature and polarization anisotropies, and the best prospect for detecting the cluster signal is via cross-correlation. For high-redshift clusters, the correlation with the local temperature is weaker and the power in the uncorrelated component of the cluster polarization can be used to enhance detection. We derive linear and quadratic maximum-likelihood estimators for these cases, and forecast signal-to-noise values for the Sunyaev-Zeldovich (SZ) surveys of a Planck-like mission and SPTPol. Our estimators represent an optimal “stacking” analysis of the polarization from clusters. We find that the detectability of the effect is sensitive to the cluster gas density distribution, as well as the telescope resolution, cluster redshift distribution, and sky coverage. We find that the effect is too small to be detected in current and near-future SZ surveys without dedicated polarization follow-up, and that a rms noise on the Stokes parameters of roughly $1\mu \mathrm{K}$-arcmin for each cluster field is required for a $2\sigma$ detection, assuming roughly 550 clusters are observed. We show that ACTPol is in a better position to observe the effect than SPTPol due to its advantageous survey location on the sky, and we discuss the novel spatial dependence of the signal. We discuss and quantify potential biases from the kinetic part of the signal caused by the relative motion of the cluster with respect to the CMB, and from the background CMB polarization behind the cluster, discussing ways in which these biases might be mitigated. Our formalism should be important for next-generation CMB polarization missions, which we argue will be able to measure this effect with high signal-to-noise. This will allow for an important consistency test of the $\mathrm{\Lambda }\mathrm{CDM}$ model on scales that are inaccessible to other probes.