The final state obtained when a Higgs boson decays to a photon and a $Z$ boson has been mostly overlooked in current searches for a light Higgs boson. However, when the $Z$ boson decays leptonically, all final state particles in this channel can be measured, allowing for accurate reconstructions of the Higgs mass and angular correlations. We determine the sensitivity of the Large Hadron Collider (LHC) running at center of mass energies of 8 and 14 TeV to Standard Model (SM) Higgs bosons with masses in the 120–130 GeV range. For the 8 TeV LHC, sensitivity to several times the SM cross section times branching ratio may be obtained with 20 inverse femtobarns of integrated luminosity, while for the 14 TeV LHC, the SM rate is probed with about 100 inverse femtobarns of integrated luminosity.

In a sample of $471\times {10}^6$ $B\overline{B}$ events collected with the BABAR detector at the PEP-II $e^{+}{e}^{-}$ collider we study the rare decays $B\to K^{(*)}{\ell }^{+}{\ell }^{-}$, where ${\ell }^{+}{\ell }^{-}$ is either $e^{+}{e}^{-}$ or ${\mu }^{+}{\mu }^{-}$. We report results on partial branching fractions and isospin asymmetries in seven bins of dilepton mass-squared. We further present $CP$ and lepton-flavor asymmetries for dilepton masses below and above the $J/\psi$ resonance. We find no evidence for $CP$ or lepton-flavor violation. The partial branching fractions and isospin asymmetries are consistent with the Standard Model predictions and with results from other experiments.

We show to next-to-leading order accuracy in the strong coupling ${\alpha }_s$ how the collinear factorization properties of QCD in the generalized Bjorken regime relate exclusive amplitudes for spacelike and timelike hadronic processes. This yields simple space-to-timelike relations linking the amplitudes for electroproduction of a photon or meson to those for photo- or mesoproduction of a lepton pair. These relations constitute a new test of the relevance of leading twist analyses of experimental data.

We study the geodesic motion of test particles in the space-time of two Abelian-Higgs strings interacting via their magnetic fields. These bound states of cosmic strings constitute a field theoretical realization of p-q-strings that are predicted by inflationary models rooted in string theory, e.g., brane inflation. In contrast to previously studied models describing p-q-strings our model possesses a Bogomolnyi-Prasad-Sommerfield limit. If cosmic strings exist it would be exciting to detect them by direct observation. We propose that this can be done by the observation of test particle motion in the space-time of these objects. In order to be able to make predictions we have to solve the field equations describing the configuration as well as the geodesic equation numerically. The geodesics can then be classified according to the test particle’s energy, angular momentum, and momentum along the string axis. We find that the interaction of two Abelian-Higgs strings can lead to the existence of bound orbits that would be absent without the interaction. We also discuss the minimal and maximal radius of orbits and comment on possible applications in the context of gravitational wave emission.

The higher-dimensional Weyl curvature induces on the brane a new source of gravity. This Weyl fluid of geometrical origin (reducing in the spherically symmetric, static configuration to a dark radiation and dark pressure) modifies spacetime geometry around galaxies and has been shown to explain the flatness of galactic rotation curves. Independent observations for discerning between the Weyl fluid and other dark matter models are necessary. Gravitational lensing could provide such a test. Therefore we study null geodesics and weak gravitational lensing in the dark radiation dominated region of galaxies in a class of spherically symmetric braneworld metrics. We find that the lensing profile in the braneworld scenario is distinguishable from dark matter lensing, despite both the braneworld scenario and dark matter models fitting the rotation curve data. In particular, in the asymptotic regions, light deflection is 18% enhanced as compared to dark matter halo predictions. For a linear equation of state of the Weyl fluid, we further find a critical radius below which braneworld effects reduce, while above it they amplify light deflection. This is in contrast to any dark matter model, the addition of which always increases the deflection angle.

We utilize the Canny edge detection algorithm as an estimator for primordial non-Gaussianities. In preliminary tests on simulated sky patches with a window size of 57 degrees and multipole moments $l$ up to 1024, we find a 99% distinction between maps with local non-Gaussianity $|f_{\mathrm{NL}}|\approx 450$ and Gaussian maps. We present evidence that high-resolution cosmic microwave background studies will strongly enhance the sensitivity of the Canny algorithm to non-Gaussianity, making it a promising technique to estimate primordial non-Gaussianity.

This article describes the current most precise measurement of the $WZ$ production cross section as well as limits on anomalous $WWZ$ couplings at a center-of-mass energy of 1.96 TeV in proton-antiproton collisions for the Collider Detector at Fermilab (CDF). $WZ$ candidates are reconstructed from decays containing three charged leptons and missing energy from a neutrino, where the charged leptons are either electrons or muons. Using data collected by the CDF II detector ($7.1{\mathrm{fb}}^{-1}$ of integrated luminosity), 63 candidate events are observed with the expected background contributing $8\pm 1$ events. The measured total cross section $\sigma (p\overline{p}\to WZ)={3.93}_{-0.53}^{+0.60}(\mathrm{stat}{)}_{-0.46}^{+0.59}(\mathrm{syst})\mathrm{pb}$ is in good agreement with the standard model prediction of $3.50\pm 0.21$. The same sample is used to set limits on anomalous $WWZ$ couplings.

We study the gravity duals of supercurrent solutions in the anti–de Sitter (AdS) black hole background with general phase structure to describe both the first- and the second-order phase transitions at finite temperature in strongly interacting systems. We argue that the conductivity and the pair susceptibility can be possible phenomenological indications to distinguish the order of phase transitions. We extend our discussion to the AdS soliton configuration. Different from the black hole spacetime, in the probe limit, the first-order phase transition cannot be brought by introducing the spatial component of the vector potential of the gauge field in the AdS soliton background.

We use the Villain approximation to show that the Gross-Witten model, in the weak- and strong-coupling limits, is related to the unitary matrix model that describes $U(N)$ Chern-Simons theory on $S^3$. The weak-coupling limit corresponds to the $q\to 1$ limit of the Chern-Simons theory while the strong-coupling regime is related to the $q\to 0$ limit. In the latter case, there is a logarithmic relationship between the respective coupling constants. We also show how the Chern-Simons matrix model arises by considering two-dimensional Yang-Mills theory with the Villain action. This leads to a $U(1{)}^N$ theory which is the Abelianization of 2d Yang-Mills theory with the heat-kernel lattice action. In addition, we show that the character expansion of the Villain lattice action gives the $q$ deformation of the heat kernel as it appears in $q$-deformed 2d Yang-Mills theory. We also study the relationship between the unitary and Hermitian Chern-Simons matrix models and the rotation of the integration contour in the corresponding integrals.

In this work we study the well-known contact term, which is the key element in resolving the so-called $U(1{)}_A$ problem in QCD. We study this term using the dual holographic description. We argue that in the dual picture the contact term is saturated by the D2-branes which can be interpreted as the tunneling events in Minkowski space-time. We quote a number of direct lattice results supporting this identification. We also argue that the contact term receives a Casimir-like correction $\sim ({\Lambda }_{\mathrm{QCD}}R{)}^{-1}$ rather than the naively expected $\exp (-{\Lambda }_{\mathrm{QCD}}R)$ when the Minkowski space-time ${\mathcal{R}}_{3,1}$ is replaced by a large but finite manifold with a size $R$. Such a behavior is consistent with other quantum field theory (QFT)-based computations when powerlike corrections are due to nontrivial properties of topological sectors of the theory. In holographic description, such a behavior is due to a massless Ramond-Ramond (RR) field living in the bulk of multidimensional space when powerlike corrections is a natural outcome of a massless RR field. In many respects, the phenomenon is similar to the Aharonov-Casher effect when the “modular electric field” can penetrate into a superconductor where the electric field is exponentially screened. The role of “modular operator” from the Aharonov-Casher effect is played by a large-gauge transformation operator $\mathcal{T}$ in four-dimensional QCD, resulting in the transparency of the system to topologically nontrivial pure gauge configurations. We discuss some profound consequences of our findings. In particular, we speculate that a slow variation of the contact term in expanding universe might be the main source of the observed dark energy.

We consider Weyl symmetric structure of the classical vacuum in quantum chromodynamics. In the framework of formalism of gauge invariant Abelian projection, we show that classical vacuums can be constructed in terms of Killing vector fields on the group $SU(3)$. Consequently, homotopic classes of Killing vector fields determine the topological structure of the vacuum. In particular, the second homotopy group ${\pi }_2(SU(3)/U(1)\times U(1))$ describes all topologically nonequivalent vacuums that are classified by two topological numbers. Starting with a given Killing vector field, one can construct vacuums forming a Weyl sextet representation. An interesting feature of $SU(3)$ gauge theory is that it admits a Weyl symmetric vacuum represented by a linear superposition of the vacuums from the Weyl vacuum sextet. A nontrivial manifestation of the Weyl symmetry is demonstrated on monopole solutions. We construct a family of finite energy monopole solutions in Yang-Mills-Higgs theory that includes the Weyl monopole sextet. We conjecture that a similar Weyl symmetric vacuum structure can be realized at quantum level in quantum chromodynamics.

We derive a stationary and axisymmetric black hole solution to quadratic order in the spin angular momentum. The previously found, linear-in-spin terms modify the odd-parity sector of the metric, while the new corrections appear in the even-parity sector. These corrections modify the quadrupole moment, as well as the (coordinate-dependent) location of the event horizon and the ergoregion. Although the linear-in-spin metric is of Petrov type D, the quadratic-order terms render it of type I. The metric does not possess a second-order Killing tensor or a Carter-like constant. The new metric does not possess closed timelike curves or spacetime regions that violate causality outside of the event horizon. The new, even-parity modifications to the Kerr metric decay less rapidly at spatial infinity than the leading order in spin, odd-parity ones, and thus, the former are more important when considering black holes that are rotating moderately fast. We calculate the modifications to the Hamiltonian, binding energy and Kepler’s third law. These modifications are crucial for the construction of gravitational wave templates for black hole binaries, which will enter at second post-Newtonian order, just like dissipative modifications found previously.

We investigate five-dimensional vacuum solutions which represent rotating multiblack holes in asymptotically Kaluza-Klein spacetimes. We show that multiblack holes rotate maximally along extra dimension, and stationary configurations in vacuum are achieved by the balance of the gravitational attraction force and repulsive force caused by the rotations of black holes. We also show that each black hole can have the different topology of the lens space in addition to the spherical topology, and the mass of black holes is quantized by the size of the extra dimension and horizon topology.

In this paper we discuss the entropy of quantum black holes in the Loop quantum gravity; formalism when the number of punctures on the horizon is treated as a quantum hair, that is we compute the black hole entropy in the grand canonical (area) ensemble. The entropy is a function of both the average area and the average number of punctures and bears little resemblance to the Bekenstein-Hawking entropy. In the thermodynamic limit, both the “temperature” and the chemical potential can be shown to be functions only of the average area per puncture. At a fixed temperature, the average number of punctures becomes proportional to the average area and we recover the Bekenstein-Hawking area-entropy law to leading order provided that the Barbero-Immirzi parameter, $\gamma$, is appropriately fixed. This also relates the chemical potential to $\gamma$. We obtain a subleading correction, which differs in signature from that obtained in the microcanonical and canonical ensembles in its sign but agrees with earlier results in the grand canonical ensemble.

We consider the Eddington-Born-Infeld (EBI) model here without assuming any cosmological constant. The EBI scalar field is supposed to play a role of both dark matter and dark energy. Different eras in cosmology are reconstructed for the model. A comparison is drawn with the $\Lambda \mathrm{CDM}$ model using Supernova Type Ia data, WMAP7 and baryon acoustic oscillations data. It seems that the EBI field in this form does not give a good fit to observational data in comparison to the $\Lambda \mathrm{CDM}$ model.

We propose selection cuts on the LHC $t\overline{t}$ production sample which should enhance the sensitivity to new physics signals in the study of the $t\overline{t}$ invariant mass distribution. We show that selecting events in which the $t\overline{t}$ object has little transverse and large longitudinal momentum enlarges the quark-fusion fraction of the sample and therefore increases its sensitivity to new physics which couples to quarks and not to gluons. We find that systematic error bars play a fundamental role and assume a simple model for them. We check how a non-visible new particle would become visible after the selection cuts enhance its resonance bump. A final realistic analysis should be done by the experimental groups with a correct evaluation of the systematic error bars.

We present a detailed analysis of nucleon electromagnetic and axial form factors in a holographic soft-wall model. This approach is based on an action which describes hadrons with broken conformal invariance and incorporates confinement through the presence of a background dilaton field. For $N_c=3$ we describe the nucleon structure in a superposition of a three-valence quark state with high Fock states including an adjustable number of partons (quarks, antiquarks and gluons) via studying the dynamics of 5D fermion fields of different scaling dimension in anti-de Sitter space. According to the gauge/gravity duality the 5D fermion fields of different scaling dimension correspond to the Fock state components with a specific number of partons. In the present application we restrict to the contribution of 3, 4 and 5 parton components in the nucleon Fock state. With a minimal number of free parameters (dilaton scale parameter, mixing parameters of partial contributions of Fock states, coupling constants in the effective Lagrangian) we achieve a reasonable agreement with data for the nucleon form factors.

We evaluate all two-body decay modes of the heavy scalar top quark in the minimal supersymmetric standard model with complex parameters (cMSSM) and no generation mixing. The evaluation is based on a full one-loop calculation of all decay channels, also including hard QED and QCD radiation. The renormalization of the complex parameters is described in detail. The dependence of the heavy scalar top quark decay on the relevant cMSSM parameters is analyzed numerically, including also the decay to Higgs bosons and another scalar quark or to a top quark and the lightest neutralino. We find sizable contributions to many partial decay widths and branching ratios. They are roughly of $\mathcal{O}(10\%)$ of the tree-level results, but can go up to 30% or higher. These contributions are important for the correct interpretation of scalar top quark decays at the LHC and, if kinematically allowed, at the ILC. The evaluation of the branching ratios of the heavy scalar top quark will be implemented into the Fortran code FeynHiggs.

We present a new determination of the $B$ and $B_s$ meson decay constants using nonrelativistic quantum chromodynamics (NRQCD) $b$-quarks, highly improved staggered quark (HISQ) light and strange valence quarks and the MILC collaboration $N_f=2+1$ lattices. The new calculations improve on HPQCD’s earlier work with NRQCD $b$-quarks by replacing AsqTad with HISQ valence quarks, by including a more chiral MILC fine ensemble in the analysis, and by employing better tuned quark masses and overall scale. We find $f_B=0.191(9)\mathrm{GeV}$, $f_{B_s}=0.228(10)\mathrm{GeV}$ and $f_{B_s}/f_B=1.188(18)$. Combining the new value for $f_{B_s}/f_B$ with a recent very precise determination of the $B_s$ meson decay constant based on HISQ $b$-quarks, $f_{B_s}=0.225(4)\mathrm{GeV}$, leads to $f_B=0.189(4)\mathrm{GeV}$. With errors of just 2.1% this represents the most precise $f_B$ available today.