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.

A half–Bogomol’nyi-Prasad-Sommerfeld circular Wilson loop in $\mathcal{N}=4$ $SU(N)$ supersymmetric Yang-Mills theory in an arbitrary representation is described by a Gaussian matrix model with a particular insertion. The additional entanglement entropy of a spherical region in the presence of such a loop was recently computed by Lewkowycz and Maldacena using exact matrix model results. In this paper we utilize the supergravity solutions that are dual to such Wilson loops in a representation with order $N^2$ boxes to calculate this entropy holographically. Employing the matrix model results of Gomis, Matsuura, Okuda and Trancanelli we express this holographic entanglement entropy in a form that can be compared with the calculation of Lewkowycz and Maldacena. We find complete agreement between the matrix model and holographic calculations.

We compute the scattering cross section of Reissner-Nordström black holes for the case of an incident electromagnetic wave. We describe how scattering is affected by both the conversion of electromagnetic to gravitational radiation, and the parity dependence of phase shifts induced by the black hole charge. The latter effect creates a helicity-reversed scattering amplitude that is nonzero in the backward direction. We show that from the character of the electromagnetic wave scattered in the backward direction it is possible, in principle, to infer if a static black hole is charged.

We present the first results of searches for axions and axionlike particles with the XENON100 experiment. The axion-electron coupling constant, $g_{\mathrm{Ae}}$, has been probed by exploiting the axioelectric effect in liquid xenon. A profile likelihood analysis of 224.6 live days $\times$ 34-kg exposure has shown no evidence for a signal. By rejecting $g_{\mathrm{Ae}}$ larger than $7.7\times {10}^{-12}$ (90% C.L.) in the solar axion search, we set the best limit to date on this coupling. In the frame of the DFSZ and KSVZ models, we exclude QCD axions heavier than 0.3 and $80\mathrm{eV}/{\mathrm{c}}^2$, respectively. For axionlike particles, under the assumption that they constitute the whole abundance of dark matter in our galaxy, we constrain $g_{\mathrm{Ae}}$ to be lower than $1\times {10}^{-12}$ (90% C.L.) for masses between 5 and $10\mathrm{keV}/{\mathrm{c}}^2$.

An improved measurement of the mass of the Higgs boson is derived from a combined fit to the reconstructed invariant mass spectra of the decay channels $H\to \gamma \gamma$ and $H\to Z{Z}^{*}\to 4\ell$. The analysis uses the $pp$ collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at center-of-mass energies of 7 TeV and 8 TeV, corresponding to an integrated luminosity of $25{\mathrm{fb}}^{-1}$. The measured value of the Higgs boson mass is $m_H=125.36\pm 0.37(\text{stat})\pm 0.18(\text{syst})\mathrm{GeV}$. This result is based on improved energy-scale calibrations for photons, electrons, and muons as well as other analysis improvements, and supersedes the previous result from ATLAS. Upper limits on the total width of the Higgs boson are derived from fits to the invariant mass spectra of the $H\to \gamma \gamma$ and $H\to Z{Z}^{*}\to 4\ell$ decay channels.

In this paper we discuss search strategies at the LHC for light electroweak gauginos which are mostly wino-like, Higgsino-like or an admixture. These states are typically degenerate with decay products that are less energetic and hence difficult to detect. In addition, their production cross sections at a hadron collider are suppressed compared to colored states such as the gluinos. In order to detect these states one needs to trigger on initial-or final-state radiation. Many previous analyses have focussed on mono-jet and mono-photon triggers. In this paper we argue and show that these triggers are unlikely to succeed, due to the large background from QCD backgrounds for the mono-jet searches and the fact that the $p_T$ distribution of the mono-photons are rapidly decreasing functions of $p_T$. We show this with both an analytic calculation of photons in the initial-state radiation and also a detailed numerical analysis. We then argue that mono-$Z$ triggers, from $Z$ decaying into charged leptons may well provide the best search strategy, in particular for Higgsino-like and mixed cases.

Indirect constraints on the total Higgs width ${\mathrm{\Gamma }}_h$ from correlating Higgs signal strengths with cross-section measurements in the off-shell region for $p(g)p(g)\to 4\ell$ production have received considerable attention recently, and the CMS Collaboration have published a first measurement. We revisit this analysis from a new physics and unitarity constraints perspective and conclude that limits on ${\mathrm{\Gamma }}_h$ obtained in this fashion are not reliable unless we make model-specific assumptions, which cannot be justified at the current stage of the LHC program. Relaxing the ${\mathrm{\Gamma }}_h$ interpretation, we discuss the merits of high invariant mass cross-section measurements in the context of Higgs $\mathcal{C}\mathcal{P}$ analyses, higher-dimensional operator testing, and resolved new physics in the light of electroweak precision constraints beyond effective theory limitations. Furthermore, we show that a rather model-independent LHC constraint can be obtained from adapting the $gg\to 4\ell$ analysis to the weak boson fusion channels at lower statistical yield.

We explore the cosmological consequences of kinetically mixed dark photons with a mass between 1 MeV and 10 GeV and an effective electromagnetic fine structure constant as small as $10^{-38}$. We calculate the freeze-in abundance of these dark photons in the early universe and explore the impact of late decays on big bang nucleosynthesis and the cosmic microwave background. This leads to new constraints on the parameter space of mass $m_V$ vs kinetic mixing parameter $\kappa$.

We revisit the computation of logarithmic corrections to black holes with $\mathcal{N}\ge 2$ supersymmetry. We employ an on-shell method that takes advantage of the symmetries in the ${\mathrm{AdS}}_2\times S^2$ near horizon geometry. For bulk modes interactions are incorporated through the spectrum of chiral primaries that we derive afresh. The spectrum of boundary states is computed explicitly by analyzing gauge variations. Elementary heat kernels in four and two dimensions then give the logarithmic corrections to the black hole entropy. Our computation represents a streamlined and simplified derivation that agrees with the results recently found by A. Sen.

We analyze the two-Higgs-doublet models (2HDMs) of Type I and Type II for consistency with the latest measurements of the $\sim 125.5\mathrm{GeV}$ Higgs-like signal at the LHC. To this end, we perform scans of the 2HDM parameter space taking into account all relevant pre-LHC constraints as well as the most recent limits coming from searches for heavy Higgs-like states at the LHC. The current status of the 2HDMs of Type I and Type II is discussed assuming that the observed 125.5 GeV state is one of the two $CP$-even Higgs bosons, either the lighter $h$ or the heavier $H$. Implications for future experiments, including expectations regarding other lighter or heavier Higgs bosons, are given. The possible importance of heavier Higgs bosons feeding the signals for the 125.5 GeV state is also evaluated.

The post-Newtonian (PN) approximation is still the most widely used approach to obtaining explicit solutions in general relativity, especially for the relativistic two-body problem with arbitrary mass ratio. Within many of its applications, it is often required to use a regularization procedure. Though frequently misunderstood, the regularization is essential for waveform generation without reference to the internal structure of orbiting bodies. In recent years, direct comparison with the self-force approach, constructed specifically for highly relativistic particles in the extreme mass ratio limit, has enabled preliminary confirmation of the foundations of both computational methods, including their very independent regularization procedures, with high numerical precision. In this paper, we build upon earlier work to carry this comparison still further, by examining next-to-next-to-leading order contributions beyond the half integral 5.5PN conservative effect, which arise from terms to cubic and higher orders in the metric and its multipole moments, thus extending scrutiny of the post-Newtonian methods to one of the highest orders yet achieved. We do this by explicitly constructing tail-of-tail terms at 6.5 and 7.5PN order, computing the redshift factor for compact binaries in the small mass ratio limit, and comparing directly with numerically and analytically computed terms in the self-force approach, obtained using solutions for metric perturbations in the Schwarzschild space-time, and a combination of exact series representations possibly with more typical PN expansions. While self-force results may be relativistic but with restricted mass ratio, our methods, valid primarily in the weak-field slowly moving regime, are nevertheless in principle applicable for arbitrary mass ratios.

We study the entanglement entropy of excited states in two-dimensional conformal field theories (CFTs). In particular, we consider excited states obtained by acting on a vacuum with primary operators. We show that the entanglement entropy increases by a finite constant amount under its time evolution. Moreover, in rational conformal field theories, we prove that this increase of the (both Renyi and von Neumann) entanglement entropy always coincides with the log of the quantum dimension of the primary operator.

We prove the generalized covariant entropy bound, $\mathrm{\Delta }S\le (A-A^{\prime })/4G\hslash$, for light-sheets with initial area $A$ and final area $A^{\prime }$. The entropy $\mathrm{\Delta }S$ is defined as a difference of von Neumann entropies of an arbitrary state and the vacuum, with both states restricted to the light-sheet under consideration. The proof applies to free fields, in the limit where gravitational backreaction is small. We do not assume the null energy condition. In regions where it is violated, we find that the bound is protected by the defining property of light-sheets: that their null generators are nowhere expanding.

We discuss the general structure and observational consequences of some of the simplest versions of chaotic inflation in supergravity in relation to the data by Planck 2013 and BICEP2. We show that minimal modifications to the simplest quadratic potential are sufficient to provide a controllable tensor mode signal and a suppression of CMB power at large angular scales.