We perform a Bayesian analysis of pulsar-timing residuals from the NANOGrav pulsar-timing array to search for a specific form of stochastic narrow-band signal produced by oscillating gravitational potential (Gravitational Potential Background) in the galactic halo. Such oscillations arise in models of warm dark matter composed of an ultralight massive scalar field ($m\sim 10^{-23}\mathrm{eV}$), recently considered by Khmelnitsky and Rubakov [J. Cosmol. Astropart. Phys. 2 (2014) 019]. In the monochromatic approximation, the stringent upper limit (95% C.L.) on the variable gravitational potential amplitude is found to be ${\mathrm{\Psi }}_c<1.14\times 10^{-15}$, corresponding to the characteristic strain $h_c=2\sqrt{3}{\mathrm{\Psi }}_c<4\times 10^{-15}$ at $f=1.75\times 10^{-8}\mathrm{Hz}$. In the narrow-band approximation, the upper limit of this background energy density is ${\mathrm{\Omega }}_{\mathrm{GPB}}<1.27\times 10^{-9}$ at $f=6.2\times 10^{-9}\mathrm{Hz}$. These limits are an order of magnitude higher than the expected signal amplitude. The applied analysis of the pulsar-timing residuals can be used to search for any narrow-band stochastic signals with different correlation properties. As a by-product, parameters of the red noise present in four NANOGrav pulsars ($\mathrm{J}1713+0747$, $\mathrm{J}2145-0750$, $\mathrm{B}1855+09$, and $\mathrm{J}1744-1134$) have been evaluated.

The recent discovery of the 125.5 GeV Higgs boson at the LHC has fueled interest in the next-to-minimal supersymmetric standard model (NMSSM) as it may require less fine-tuning than the minimal model to accommodate such a heavy Higgs. To this end we present Bayesian naturalness priors to quantify fine-tuning in the (N)MSSM. These priors arise automatically as Occam razors in Bayesian model comparison and generalize the conventional Barbieri-Giudice measure. In this paper we show that the naturalness priors capture features of both the Barbieri-Giudice fine-tuning measure and a simple ratio measure that has been used in the literature. We also show that according to the naturalness prior the constrained version of the NMSSM is less tuned than the CMSSM.

We study the prospects for LHC discovery of a narrow resonance that decays to two Higgs bosons, using the final state of two photons and two bottom jets. Our work is motivated in part by a scenario in which two-body flavor-preserving decays of the top squark are kinematically forbidden. Stoponium, a hadronic bound state of the top squark and its antiparticle, will then form, and may have a large branching fraction into the two Higgs boson final state. We estimate the cross section needed for a 5-sigma discovery at the 14 TeV LHC for such a narrow di-Higgs resonance, using the invariant mass distributions of the final state bottom jets and photons, as a function of the integrated luminosity. The results are also applicable to any other di-Higgs resonance produced by gluon fusion.

The value of the quarkonium wave function at the origin is an important quantity for studying many physical problems concerning a heavy quarkonium. This is because it is widely used to evaluate the production and decay amplitudes of the heavy quarkonium within the effective field theory framework, e.g., the nonrelativistic QCD (NRQCD). In this paper, the values of the Schrödinger radial wave function or its first nonvanishing derivative at zero quark-antiquark separation, i.e., $|(|c\overline{c})[n]⟩$, $|(|b\overline{c})[n]⟩$, and $|(b\overline{b})[n]⟩$ quarkonium, have been tabulated under five potential models with new parameters for the heavy quarkonium. Moreover, the production of the lower-level Fock states $|(b\overline{Q})[1S]⟩$ and $|(b\overline{Q})[1P]⟩$, together with the higher excited Fock states $|(b\overline{Q})[nS]⟩$ and $|(b\overline{Q})[nP]⟩$ ($Q$ stands for the $c$ or $b$ quark; $n=2,\dots ,6$) through top quark decays has been studied with the new values of heavy quarkonium wave functions at the origin under the framework of NRQCD. At the LHC with the luminosity $\mathcal{L}\propto 10^{34}{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$ and the center-of-mass energy $\sqrt{S}=14\mathrm{TeV}$, sizable heavy quarkonium events can be produced through top quark decays, i.e., $4\times 10^5{B}_c$ and $B_c^{*}$, and $2\times 10^4{\eta }_b$, and $\mathrm{\Upsilon }$ events per year can be obtained according to our calculation.

In this paper, we study phenomenologically interesting soft radiation distributions in massless QCD. Specifically, we consider the emission of two soft partons off of a pair of lightlike Wilson lines, in either the fundamental or the adjoint representation, at next-to-leading order. Our results are an essential component of the next-to-next-to-next-to-leading order threshold corrections to both Higgs boson production in the gluon fusion channel and Drell-Yan lepton production. Our calculations are consistent with the recently published results for Higgs boson production. As a nontrivial cross-check on our analysis, we rederive a recent prediction for the Drell-Yan threshold cross section using a completely different strategy. Our results are compact, valid to all orders in the dimensional regularization parameter, and expressed in terms of pure functions.

The PHENIX experiment at the Relativistic Heavy Ion Collider has measured low-mass vector-meson, $\omega$, $\rho$, and $\varphi$, production through the dimuon decay channel at forward rapidity ($1.2<|y|<2.2$) in $p+p$ collisions at $\sqrt{s}=200\mathrm{GeV}$. The differential cross sections for these mesons are measured as a function of both $p_T$ and rapidity. We also report the integrated differential cross sections over $1<p_T<7\mathrm{GeV}/c$ and $1.2<|y|<2.2$: $d\sigma /dy(\omega +\rho \to \mu \mu )=80\pm 6(\mathrm{stat})\pm 12(\mathrm{syst})\mathrm{nb}$ and $d\sigma /dy(\varphi \to \mu \mu )=27\pm 3(\mathrm{stat})\pm 4(\mathrm{syst})\mathrm{nb}$. These results are compared with midrapidity measurements and calculations.

We present a measurement of the electric charge of top quarks using $t\overline{t}$ events produced in $p\overline{p}$ collisions at the Tevatron. The analysis is based on fully reconstructed $t\overline{t}$ pairs in $\text{lepton}+\text{jets}$ final states. Using data corresponding to $5.3{\mathrm{fb}}^{-1}$ of integrated luminosity, we exclude the hypothesis that the top quark has a charge of $Q=-4/3e$ at a significance greater than 5 standard deviations. We also place an upper limit of 0.46 on the fraction of such quarks that can be present in an admixture with the standard model top quarks ($Q=+2/3e$) at a 95% confidence level.

In this paper, we study the M5-brane configurations in ${\mathrm{AdS}}_4\times Q^{1,1,1}$ spacetime. We consider the configurations with an ${\mathrm{AdS}}_2$ factor embedding into ${\mathrm{AdS}}_4$ and manage to construct two solutions, which could be dual to line defects in the boundary gauge theory. Moreover, we discuss their Bogomol’nyi-Prasad-Sommerfield (BPS) nature and find that neither of them is supersymmetric. We show that the M5-brane with an $R_t$ or an ${\mathrm{AdS}}_3$ factor found previously is half-BPS.

A generalization of the action principle of classical mechanics, motivated by the closed time path scheme of quantum field theory, is presented to deal with initial condition problems and dissipative forces. The similarities of the classical and the quantum cases are underlined. In particular, effective interactions that describe classical dissipative forces represent the system-environment entanglement. The relation between the traditional effective theories and their closed time path extension is briefly discussed, and a few qualitative examples are mentioned.

Using functional renormalization methods, we study the one-loop renormalization group evolution of theories with four scalars, at second order in the derivative expansion, in which electroweak symmetry is nonlinearly realized. In this framework we study the stability of $O(4)$ symmetry and find the $O(4)$-violating eigenperturbations and their corresponding eigenspectrum around three different geometries of the target space, namely those of the flat space, cylinder, and sphere.

We discuss a Chern-Simons (CS) scalar field around a rapidly rotating black hole in dynamical CS modified gravity. The CS correction can be obtained perturbatively by considering the Kerr spacetime to be the background. We obtain the CS scalar field solution around the black hole analytically and numerically, assuming a stationary and axisymmetric configuration. The scalar field diverges on the inner horizon when we impose the boundary conditions that the scalar field be regular on the outer horizon and vanish at infinity. Therefore, the CS scalar field becomes problematic on the inner horizon.

We examine reheating in the two-field matter bounce cosmology. In this model, the Universe evolves from a matter-dominated phase of contraction to an Ekpyrotic phase of contraction before the nonsingular bounce. The Ekpyrotic phase frees the model from unwanted anisotropies, but leaves the Universe cold and empty of particles after the bounce. For this reason, we explore two particle production mechanisms which take place during the course of the cosmological evolution: Parker particle production where the matter field couples only to gravity and particle creation via interactions between the matter field and the bounce field. Although we show that both mechanisms can produce particles in this model, we find that Parker particle production is sufficient to reheat the Universe to high temperatures. Thus there is a priori no need to add an interaction term to the Lagrangian of the model. Still, particle creation via interactions can contribute to the formation of matter and radiation, but only if the coupling between the fields is tuned to be large.

Squeezed states of light have been successfully employed in interferometric gravitational-wave detectors to reduce quantum noise, thus becoming one of the most promising options for extending the astrophysical reach of the generation of detectors currently under construction worldwide. In these advanced instruments, quantum noise will limit sensitivity over the entire detection band. Therefore, to obtain the greatest benefit from squeezing, the injected squeezed state must be filtered using a long-storage-time optical resonator, or “filter cavity,” so as to realize a frequency-dependent rotation of the squeezed quadrature. While the ultimate performance of a filter cavity is determined by its storage time, several practical decoherence and degradation mechanisms limit the experimentally achievable quantum noise reduction. In this paper we develop an analytical model to explore these mechanisms in detail. As an example, we apply our results to the 16 m filter cavity design currently under consideration for the Advanced LIGO interferometers.

Laser frequency stabilization is a critical part of the interferometry measurement system of space-based gravitational wave observatories such as the Laser Interferometer Space Antenna (LISA). Arm locking as a proposed frequency stabilization technique transfers the stability of the long arm lengths to the laser frequency. The arm locking sensor synthesizes an adequately filtered linear combination of the interspacecraft phase measurements to estimate the laser frequency noise, which can be used to control the laser frequency. At the University of Florida we developed the hardware-based University of Florida LISA Interferometer Simulator to study and verify laser frequency noise reduction and suppression techniques under realistic LISA-like conditions. These conditions include the variable Doppler shifts among the spacecraft, LISA-like signal travel times, optical transponders, realistic laser frequency, and timing noise. We review the different types of arm locking sensors and discuss their expected performance in LISA. The presented results are supported by results obtained during experimental studies of arm locking under relevant LISA-like conditions. We measured the noise suppression as well as initial transients and frequency pulling in the presence of Doppler frequency errors. This work has demonstrated the validity and feasibility of arm locking in LISA.

We consider rapidly rotating black holes and neutron stars in dilatonic Einstein-Gauss-Bonnet (EGBd) theory and determine their quadrupole moments, which receive a contribution from the dilaton. The quadrupole moment of EGBd black holes can be considerably larger than the Kerr value. For neutron stars, the universality property of the $\widehat{I}$-$\widehat{Q}$ relation between the scaled moment of inertia and the scaled quadrupole moment appears to extend to EGBd theory.

We develop the modification of the top-quark condensation scenario, in which the Higgs boson is composed of all Standard Model fermions. Within this scenario, we suggest the phenomenological model with nonlocal four-fermion interactions in which at the distances of the order of $\sim 1/100\mathrm{GeV}$ the theory is represented in terms of only one Majorana spinor that carries the $U(12)$ index and, in addition, belongs to the spinor representation of $O(4)$. The Standard Model fermions are the components of this spinor. The symmetry $U(12)\otimes O(4)$ is responsible for the one-loop relation between the Higgs boson mass and the top-quark mass $M_H^2=m_t^2/2$. At the distances $\gg 1/100\mathrm{GeV}$, the mentioned symmetry is broken, and the interaction term dominates that provides the nonzero mass of the top quark. Our phenomenological model should be considered in zeta or dimensional regularization. In conventional cutoff regularization, this is equivalent to the existence of the additional counterterms that cancel all quadratic divergences. As a result, the $1/N$ expansion may be applied.

The octet-baryon axial-vector charges and the $g_1/f_1$ ratios measured in the semileptonic hyperon decays are studied up to $\mathcal{O}(p^3)$ using the covariant baryon chiral perturbation theory with explicit decuplet contributions. We clarify the role of different low-energy constants and find a good convergence for the chiral expansion of the axial-vector charges of the baryon octet, $g_1(0)$, with $\mathcal{O}(p^3)$ corrections typically around 20% of the leading ones. This is a consequence of strong cancellations between different next-to-leading-order terms. We show that considering only nonanalytic terms is not enough and that analytic terms appearing at the same chiral order play an important role in this description. The same effects still hold for the chiral extrapolation of the axial-vector charges and result in a rather mild quark-mass dependence. As a result, we report a determination of the leading-order chiral couplings, $D=0.623(61)(17)$ and $F=0.441(47)(2)$, as obtained from a completely consistent chiral analysis up to $\mathcal{O}(p^3)$. Furthermore, we note that the appearance of an unknown low-energy constant precludes the extraction of the proton octet charge from semileptonic decay data alone, which is relevant for an analysis of the composition of the proton spin.

If two particles collide near a black hole, the energy in their center of mass can, under certain conditions, grow unbounded. This is Bañados-Silk-West effect. We show that this effect retains its validity even if some force acts on a particle, provided some reasonable and weak restrictions are imposed on this force. In the present paper we discuss the case of nonextremal horizons. The result under discussion is similar to that for extremal horizons considered in our previous paper. The problem can be viewed both in its own right and as a simple setup in which this force models in the first approximation the complicated gravitational self-force.

In conformal field theories (CFTs) with a gravitational anti–de Sitter (AdS) dual it is possible to calculate the entanglement entropy of a region $A$ holographically by using the Ryu-Takayanagi formula. In this work we consider systems that are in a pure state that is not the vacuum. We study in particular the two-dimensional conformal field theory dual to type IIB string theory on ${\mathrm{AdS}}_3\times S^3\times T^4$ and focus on the $1/4$-BPS states described holographically by the two-charge microstate geometries. We discuss a general prescription for the calculation of the entanglement entropy in these geometries that are asymptotically ${\mathrm{AdS}}_3\times S^3$. In particular we study analytically the perturbative expansion for a single, short interval: we show that the first nontrivial terms in this expansion are consistent with the expected CFT structure and with previous results on the vacuum expectation values of chiral primary operators for the $1/4$-BPS configurations.

It is well known that charged black $Dp$ branes of type II string theory share a universal phase structure of van der Waals–Maxwell liquid-gas type except $D5$ and $D6$ branes. Interestingly, the phase structure of $D5$ and $D6$ branes can be changed to the universal form with the inclusion of particular delocalized charged lower-dimensional branes. For $D5$ branes, one needs to introduce delocalized $D1$ branes, and for $D6$ branes, one needs to introduce delocalized $D0$ branes to obtain the universal structure. In a previous paper [J. High Energy Phys. 04 (2013) 100], Lu with Wei study the phase structure of black $D6$ branes with the introduction of delocalized $D0$ branes in a special case when their charges are equal and the dilaton charge vanishes. In this paper, we look at the phase structure of the black $D6/D0$ system with the generic values of the parameters, which makes the analysis more involved but the structure more rich. We also provide reasons why the respective modifications of the phase structures to the universal form for the black $D5$ and $D6$ branes occur when specific delocalized lower-dimensional branes are introduced.