We describe a hybrid axion-monodromy inflation model motivated by the Dante’s Inferno scenario. In Dante’s Inferno, a two-field potential features a stable trench along which a linear combination of the two fields slowly rolls, rendering the dynamics essentially identical to that of single-field chaotic inflation. A shift symmetry allows for the Lyth bound to be effectively evaded as in other axion-monodromy models. In our proposal, the potential is concave downward near the origin and the inflaton trajectory is a gradual downward spiral, ending at a point where the trench becomes unstable. There, the fields begin falling rapidly towards the minimum of the potential and inflation terminates as in a hybrid model. We find parameter choices that reproduce observed features of the cosmic microwave background, and discuss our model in light of recent results from the BICEP2 and Planck experiments.

Ultrahigh-energy cosmic rays (UHECRs), if accelerated in the gamma-ray burst (GRB) blast wave, are expected to produce PeV-EeV neutrinos by interacting with long-lived GRB afterglow photons. Detailed spectral and temporal properties of the flux of these neutrinos depend on the GRB blast wave evolution scenario, but can last for days to years time scale in contrast to the seconds to minutes time scale for “burst” neutrino flux contemporaneous with the prompt gamma-ray emission and which has been constrained by IceCube in the $\sim 50\mathrm{TeV}-2\mathrm{PeV}$ range. We compute expected neutrino events in IceCube in the PeV-EeV range from the blast wave of long-duration GRBs, both for the diffuse flux and for individual GRBs in the nearby universe. We show that IceCube will be able to detect the diffuse GRB blast wave neutrino flux after 5 years in operation, and will be able to distinguish it from the cosmogenic neutrino flux arising from the Greisen-Zatsepin-Kuzmin process in case the ultrahigh-energy cosmic rays are heavy nuclei. We also show that EeV neutrinos from the blast wave of an individual GRB can be detected with long-term monitoring by a future high-energy extension of IceCube for redshift up to $z\sim 0.5$.

We explore new regimes of laser interferometric gravitational-wave detectors with multiple optical carriers which allow us to reduce the quantum noise of these detectors. In particular, we show that using two carriers with the opposite detunings, homodyne angles, and squeezing angles, but identical other parameters (the antisymmetric carriers), one can suppress the quantum noise in such a way that its spectrum follows the Standard Quantum Limit (SQL) at low frequencies. Relaxing this antisymmetry condition, it is also possible to slightly overcome the SQL in broadband. Combining several such pairs in the xylophone configuration, it is possible to shape the quantum noise spectrum flexibly.

We examine models and prospects for proton annihilation to dileptons, a process which violates baryon and lepton number each by two. We determine that currently Super-Kamiokande would place the most draconian bound on $pp\to {\ell }^{+}{\ell }^{+}$, ruling out new physics below a scale of $\sim 1.6\mathrm{TeV}$. We also find present and future hadron collider sensitivity to these processes. While 8 TeV LHC data exclude new physics at a scale below $\sim 800\mathrm{GeV}$, the reach of a 14 TeV LHC run is $\sim 1.8\mathrm{TeV}$, putting it on par with the sensitivity of Super-Kamiokande. On the other hand, a 100 TeV proton-proton collider would be sensitive to proton annihilation at a scale up to 10 TeV, allowing it to far exceed the reach of both Super-Kamiokande and the projected 2 TeV reach of Hyper-Kamiokande. Constraints from neutron star observation and cosmological evolution are not competitive. Therefore, although high-luminosity water Cherenkov experiments currently place the leading bounds on baryon and lepton number violation, next-generation high-energy hadron colliders will begin surpassing them in sensitivity to some $B/L$-violating processes.

We extend the study of Higgs boson couplings in the “golden” $gg\to H\to Z{Z}^{*}\to 4\ell$ channel in two important respects. First, we demonstrate the importance of off-shell Higgs boson production ($gg\to H^{*}\to ZZ\to 4\ell$) in determining which operators contribute to the $HZZ$ vertex. Second, we include the five operators of lowest nontrivial dimension, including the $Z_{\mu }{Z}^{\mu }\square H$ and $H{Z}_{\mu }\square Z^{\mu }$ operators that are often neglected. We point out that the former operator can be severely constrained by the measurement of the off-shell $H^{*}\to ZZ$ rate and/or unitarity considerations. We provide analytic expressions for the off-peak cross sections in the presence of these five operators. On shell, the $Z_{\mu }{Z}^{\mu }\square H$ operator is indistinguishable from its Standard Model counterpart $H{Z}_{\mu }{Z}^{\mu }$, while the $H{Z}_{\mu }\square Z^{\mu }$ operator can be probed, in particular, by the $Z^{*}$ invariant mass distribution.

In this article we calculate the one-loop supersymmetric QCD (SQCD) corrections to the decay ${\tilde{u}}_1\to c{\tilde{\chi }}_1^0$ in the minimal supersymmetric standard model with generic flavor structure. This decay mode is phenomenologically important if the mass difference between the lightest squark ${\tilde{u}}_1$ (which is assumed to be mainly stoplike) and the neutralino lightest supersymmetric particle ${\tilde{\chi }}_1^0$ is smaller than the top mass. In such a scenario ${\tilde{u}}_1\to t{\tilde{\chi }}_1^0$ is kinematically not allowed and searches for ${\tilde{u}}_1\to Wb{\tilde{\chi }}_1^0$ and ${\tilde{u}}_1\to c{\tilde{\chi }}_1^0$ are performed. A large decay rate for ${\tilde{u}}_1\to c{\tilde{\chi }}_1^0$ can weaken the LHC bounds from ${\tilde{u}}_1\to Wb{\chi }_1^0$ which are usually obtained under the assumption $\text{Br}[{\tilde{u}}_1\to Wb{\chi }_1^0]=100\%$. We find the SQCD corrections enhance $\mathrm{\Gamma }[{\tilde{u}}_1\to c{\tilde{\chi }}_1^0]$ by approximately 10% if the flavor violation originates from bilinear terms. If flavor violation originates from trilinear terms, the effect can be $\pm 50\%$ or more, depending on the sign of $A^t$. We note that connecting a theory of supersymmetry breaking to LHC observables, the shift from the $\overline{\text{DR}}$ to the on-shell mass is numerically very important for light stop decays.

In flavored dark matter models, dark matter can scatter off of nuclei through Higgs and photon exchange, both of which can arise from renormalizable interactions and individually lead to strong constraints from direct detection. While these two interaction channels can destructively interfere in the scattering amplitude, for a thermal relic with equal abundances for the dark matter particle and its antiparticle, this produces no effect on the total event rate. Focusing on lepton-flavored dark matter, we show that it is quite natural for dark matter to have become asymmetric during high-scale leptogenesis, and that in this case the direct detection bounds can be significantly weakened due to interference. We quantify this by mapping out and comparing the regions of parameter space that are excluded by direct detection for the symmetric and asymmetric cases of lepton-flavored dark matter. In particular, we show that the entire parameter region except for a narrow Higgs resonance window is ruled out in the symmetric case for fermion dark matter when the coupling to the Higgs dominates over the coupling to leptons, while large portions of parameter space are still allowed for the asymmetric case. The same is also true for a dark matter mass above 8 GeV for scalar dark matter when the coupling to leptons dominates over the coupling to the Higgs.

The variational method is used widely for determining the hadronic spectrum for Wilson and improved Wilson fermions. The method has not been applied to staggered fermions because the hadronic correlation functions in that formalism include terms that oscillate with Euclidean time, and they often include states of both parities. We show that with a simple modification, the variational method can also be applied to staggered fermions. In some cases the method also provides a mechanism for separating the commonly paired parity-partner states. We discuss the extension to staggered fermions and illustrate it by applying it to the calculation of the spectrum of charmed-antistrange mesons consisting of a clover charm quark and a staggered strange antiquark.

We report the observation of the baryonic decay ${\overline{B}}^0\to {\mathrm{\Lambda }}_c^{+}\overline{p}{K}^{-}{K}^{+}$ using a data sample of $471\times 10^6$ $B\overline{B}$ pairs produced in $e^{+}{e}^{-}$ annihilations at $\sqrt{s}=10.58\mathrm{GeV}$. This data sample was recorded with the BABAR detector at the PEP-II storage ring at SLAC. We find $\mathcal{B}({\overline{B}}^0\to {\mathrm{\Lambda }}_c^{+}\overline{p}{K}^{-}{K}^{+})=(2.5\pm 0.4_{(\text{stat})}\pm 0.2_{(\text{syst})}\pm 0.6_{\mathcal{B}({\mathrm{\Lambda }}_c^{+})})\times 10^{-5}$, where the uncertainties are statistical, systematic, and due to the uncertainty of the ${\mathrm{\Lambda }}_c^{+}\to p{K}^{-}{\pi }^{+}$ branching fraction, respectively. The result has a significance corresponding to 5.0 standard deviations, including all uncertainties. For the resonant decay ${\overline{B}}^0\to {\mathrm{\Lambda }}_c^{+}\overline{p}\varphi$, we determine the upper limit $\mathcal{B}({\overline{B}}^0\to {\mathrm{\Lambda }}_c^{+}\overline{p}\varphi )<1.2\times 10^{-5}$ at 90% confidence level.

We consider the possible existence of gravitationally bound general relativistic strings consisting of Bose-Einstein condensate (BEC) matter which is described, in the Newtonian limit, by the zero temperature time-dependent nonlinear Schrödinger equation (the Gross-Pitaevskii equation), with repulsive interparticle interactions. In the Madelung representation of the wave function, the quantum dynamics of the condensate can be formulated in terms of the classical continuity equation and the hydrodynamic Euler equations. In the case of a condensate with quartic nonlinearity, the condensates can be described as a gas with two pressure terms, the interaction pressure, which is proportional to the square of the matter density, and the quantum pressure, which is without any classical analogue, though, when the number of particles in the system is high enough, the latter may be neglected. Assuming cylindrical symmetry, we analyze the physical properties of the BEC strings in both the interaction pressure and quantum pressure dominated limits, by numerically integrating the gravitational field equations. In this way we obtain a large class of stable stringlike astrophysical objects, whose basic parameters (mass density and radius) depend sensitively on the mass and scattering length of the condensate particle, as well as on the quantum pressure of the Bose-Einstein gas.

We continue the study, initiated in [L. Fei, S. Giombi, and I. R. Klebanov, Phys. Rev. D 90, 025018 (2014)], of the $O(N)$ symmetric theory of $N+1$ massless scalar fields in $6-\epsilon$ dimensions. This theory has cubic interaction terms $\frac{1}{2}{g}_1\sigma ({\varphi }^i{)}^2+\frac{1}{6}{g}_2{\sigma }^3$. We calculate the three loop beta functions for the two couplings and use them to determine certain operator scaling dimensions at the IR stable fixed point up to order ${\epsilon }^3$. We also use the beta functions to determine the corrections to the critical value of $N$ below which there is no fixed point at real couplings. The result suggests a significant reduction in the critical value as the dimension is decreased to 5. We also study the theory with $N=1$, which has a $Z_2$ symmetry under $\varphi \to -\varphi$. We show that it possesses an IR stable fixed point at imaginary couplings which can be reached by flow from a nearby fixed point describing a pair of $N=0$ theories. We calculate certain operator scaling dimensions at the IR fixed point of the $N=1$ theory and suggest that, upon continuation to two dimensions, it describes a nonunitary conformal minimal model.

This article proposes a comprehensive analysis of light propagation in an anisotropic and spatially homogeneous Bianchi I universe. After recalling that null geodesics are easily determined in such a spacetime, we derive the expressions of the redshift and direction drifts of light sources; by solving analytically the Sachs equation, we then obtain an explicit expression of the Jacobi matrix describing the propagation of narrow light beams. As a by-product, we recover the old formula by Saunders for the angular diameter distance in a Bianchi I spacetime, but our derivation goes further since it also provides the optical shear and rotation. These results pave the way to the analysis of both supernovae data and weak lensing by the large-scale structure in Bianchi universes.

Gravitational-wave observations of inspiralling binary neutron-star systems can be used to measure the neutron-star equation of state (EOS) through the tidally induced shift in the waveform phase that depends on the tidal deformability parameter $\lambda$. Previous work has shown that $\lambda$, a function of the neutron-star EOS and mass, is measurable by Advanced LIGO for a single event when including tidal information up to the merger frequency. In this work, we describe a method for stacking measurements of $\lambda$ from multiple inspiral events to measure the EOS. We use Markov chain Monte Carlo simulations to estimate the parameters of a four-parameter piecewise-polytrope EOS that matches theoretical EOS models to a few percent. We find that, for “realistic” event rates ($\sim 40$ binary neutron-star inspiral events per year with signal-to-noise ratio $>8$ in a single Advanced LIGO detector), combining a year of gravitational-wave data from a three-detector network with the constraints from causality and recent high-mass neutron-star measurements, the EOS above nuclear density can be measured to better than a factor of 2 in pressure in most cases. We also find that in the mass range $1M_{\odot }–2M_{\odot }$, the neutron-star radius can be measured to better than $\pm 1\mathrm{km}$ and the tidal deformability can be measured to better than $\pm 1\times 10^{36}\mathrm{g}{\mathrm{cm}}^2{\mathrm{s}}^2$ (10%–50% depending on the EOS and mass). The overwhelming majority of this information comes from the loudest $\sim 5$ events. Current uncertainties in the post-Newtonian waveform model, however, lead to systematic errors in the EOS measurement that are as large as the statistical errors, and more accurate waveform models are needed to minimize this error.

Zero-dimensional $O(n)$-symmetric sigma models are studied using the Picard-Lefschetz integration method in the presence of small symmetry-breaking perturbations. Because of approximate symmetry, downward flows turn out to show significant structures: They slowly travel along the set of pseudoclassical points, and branch into other directions so as to span middle-dimensional integration cycles. We propose an efficient way to find such slow motions for computing Lefschetz thimbles. In the limit of symmetry restoration, we figure out that only special combinations of Lefschetz thimbles can survive as convergent integration cycles: Other integrations become divergent due to noncompactness of the complexified group of symmetry. We also compute downward flows of $O(2)$-symmetric fermionic systems, and confirm that all of these properties are true also with fermions.

The transverse polarization of $\mathrm{\Lambda }$ and $\overline{\mathrm{\Lambda }}$ hyperons produced in proton-proton collisions at a center-of-mass energy of 7 TeV is measured. The analysis uses $760\mu {\mathrm{b}}^{-1}$ of minimum bias data collected by the ATLAS detector at the LHC in the year 2010. The measured transverse polarization averaged over Feynman $x_{\mathrm{F}}$ from $5\times 10^{-5}$ to 0.01 and transverse momentum $p_{\mathrm{T}}$ from 0.8 to 15 GeV is $-0.010\pm 0.005(\text{stat})\pm 0.004(\text{syst})$ for $\mathrm{\Lambda }$ and $0.002\pm 0.006(\text{stat})\pm 0.004(\text{syst})$ for $\overline{\mathrm{\Lambda }}$. It is also measured as a function of $x_{\mathrm{F}}$ and $p_{\mathrm{T}}$, but no significant dependence on these variables is observed. Prior to this measurement, the polarization was measured at fixed-target experiments with center-of-mass energies up to about 40 GeV. The ATLAS results are compatible with the extrapolation of a fit from previous measurements to the $x_{\mathrm{F}}$ range covered by this measurement.

We construct “connected” (0, 2) sigma models starting from $n$ copies of (2, 2) $\mathrm{CP}(N-1)$ models. General aspects of models of this type (known as $T+O$ deformations) had been previously studied in the context of heterotic string theories. Our construction presents a natural generalization of the nonminimally deformed (2, 2) model with an extra (0, 2) fermion superfield on tangent bundle $\mathrm{T}[\mathrm{CP}(N-1)\times {\mathrm{C}}^1]$. We had thoroughly analyzed the latter model previously and found the exact $\beta$ function and a spontaneous breaking of supersymmetry. In contrast, in certain connected sigma models the spontaneous breaking of supersymmetry disappears. We study the connected sigma models in the large-$N$ limit finding supersymmetric vacua and determining the particle spectrum. While the Witten index vanishes in all the models under consideration, in these special cases of connected models, one can use a permutation symmetry to define a modification of the Witten index which does not vanish. This eliminates the spontaneous breaking of supersymmetry. We then examine the exact $\beta$ functions of our connected (0, 2) sigma models.

High-energy cosmic neutrino observations provide a sensitive test of Lorentz invariance violation (LIV), which may be a consequence of quantum gravity theories. We consider a class of nonrenormalizable, Lorentz invariance violating operators that arise in an effective field theory (EFT) description of Lorentz invariance violation in the neutrino sector inspired by Planck-scale physics and quantum gravity models. We assume a conservative generic scenario for the redshift distribution of extragalactic neutrino sources and employ Monte Carlo techniques to describe superluminal neutrino propagation, treating kinematically allowed energy losses of superluminal neutrinos caused by both vacuum pair emission (VPE) and neutrino splitting. We consider EFTs with both nonrenormalizable $\mathcal{C}\mathcal{P}\mathcal{T}$-odd and nonrenormalizable $\mathcal{C}\mathcal{P}\mathcal{T}$-even operator dominance. We then compare the spectra derived using our Monte Carlo calculations in both cases with the spectrum observed by IceCube in order to determine the implications of our results regarding Planck-scale physics. We find that if the dropoff in the neutrino flux above $\sim 2\mathrm{PeV}$ is caused by Planck-scale physics, rather than by a limiting energy in the source emission, a potentially significant pileup effect would be produced just below the dropoff energy in the case of $\mathcal{C}\mathcal{P}\mathcal{T}$-even operator dominance. However, such a clear dropoff effect would not be observed if the $\mathcal{C}\mathcal{P}\mathcal{T}$-odd, $\mathcal{C}\mathcal{P}\mathcal{T}$-violating term dominates.

We argue that Lovelock theories of gravity suffer from shock formation, unlike general relativity. We consider the propagation of (i) a discontinuity in curvature, and (ii) weak, high frequency, gravitational waves. Such disturbances propagate along characteristic hypersurfaces of a “background” spacetime and their amplitude is governed by a transport equation. In general relativity, the transport equation is linear. In Lovelock theories, it is nonlinear and its solutions can blow up, corresponding to the formation of a shock. We show that this effect is absent in some simple cases, e.g. a flat background spacetime, and demonstrate its presence for a plane wave background. We comment on weak cosmic censorship, the evolution of shocks, and the nonlinear stability of Minkowski spacetime, in Lovelock theories.