The Large Hadron Collider experiments are probing the evolution of the strong coupling ${\alpha }_s$ up to the TeV scale. We show how the ratio of 3 to 2 jets cross sections is affected by the presence of new physics and argue that it can be used to place a model-independent bound on new particles carrying QCD color charge. The current data potentially constrains such states to be heavier than a few hundred GeVs.

We discuss the possible production and discovery channels in $e^{+}{e}^{-}$ and $pp$ machines of the $X_b$, the bottomonium counterpart of $X(3872)$ and the putative isoscalar analogue of the charged bottomoniumlike states $Z_b$ discovered by Belle. We suggest that the $X_b$ may be close in mass to the bottomonium state ${\chi }_{b1}(3P)$, mixing with it and sharing its decay channels, just as $X(3872)$ is likely a mixture of a $\overline{D}{D}^{*}$ molecule and ${\chi }_{c1}(2P)$. Consequently, the experiments which reported observing ${\chi }_{b1}(3P)$ might have actually discovered the $X_b$, or a mixture of the two states.

We analyze the transverse single-spin asymmetry in direct photon production from proton-proton collisions, denoted $A_N^{\gamma }$, within collinear twist-3 factorization. We provide a calculation of the contribution due to quark-gluon-quark correlations in the unpolarized proton as well as summarize previous studies on those effects in the polarized proton. Both soft-gluon poles and soft-fermion poles are considered. From this complete result we then estimate $A_N^{\gamma }$, including error bands due to uncertainties in the nonperturbative inputs, at kinematics relevant for planned measurements of this observable at the Relativistic Heavy Ion Collider. We find $A_N^{\gamma }$ can allow for a “clean” extraction of the Qiu-Sterman function, which could lead to a definitive solution to the so-called “sign-mismatch” crisis. Since we use the Sivers function extracted from semi-inclusive deep-inelastic scattering to develop our input for the Qiu-Sterman function, this reaction can also make a statement about the process dependence of the Sivers function.

We show how the $Z$ boson can be generated in gluon-gluon fusion and yield two photons, via $gg\to Z\to \gamma \gamma$, through massive fermion loops only, thereby contributing events to a candidate Higgs sample in the diphoton channel. A subleading contribution also exists from $q\overline{q}\to Z\to \gamma \gamma$ events. Assuming the Standard Model, the corresponding event rates are negligible at the Large Hadron Collider stages of 7 and 8 TeV, given the luminosities collected therein (about 5 and $20{\mathrm{fb}}^{-1}$, respectively). Conversely, at 14 TeV, the first process becomes accessible for luminosities of order $300{\mathrm{fb}}^{-1}$. Finally, we show how additional fermion states entering such loops, in production, in decay or in both cases, could affect the predictions in this channel by curiously mimicking Higgs signals.

Current data of charmless $B$ meson decays to two pseudoscalar mesons ($PP$) and one vector and one pseudoscalar mesons ($VP$) are analyzed within the framework of flavor SU(3) symmetry, a working principle that we have tested by allowing symmetry breaking factors in the decay amplitudes and found to be a good approximate symmetry. In the $PP$ sector, the color-suppressed tree amplitude is found to be larger than previously known and has a strong phase of $\sim -70^{°}$ relative to the color-favored tree amplitude. We have extracted for the first time the $W$-exchange and penguin-annihilation amplitudes. The former has a size of about the QCD-penguin amplitude and a phase opposite to that of the color-favored tree amplitude, while the latter is suppressed in magnitude but gives the dominant contribution to the $B_s^0\to {\pi }^{+}{\pi }^{-}$ and ${\pi }^0{\pi }^0$ decays. In the $VP$ sector, one striking feature is that the color-suppressed tree amplitude with the spectator quark ending up in the vector meson has a large size and a strong phase of $\sim -90^{°}$ relative to the color-favored tree amplitudes. The associated electroweak penguin amplitude also has a similar strong phase and a magnitude comparable to the corresponding QCD penguin amplitude. This leads to a large branching fraction of order $10^{-6}$ for $B_s^0\to \varphi {\pi }^0$. In contrast, the color-suppressed tree, QCD penguin, and electroweak penguin amplitudes with the spectator quark ending up in the pseudoscalar meson have magnitudes more consistent with naive expectations. Besides, current data are not sufficiently precise for us to fix the $W$-exchange amplitudes. For both the $PP$ and $VP$ sectors, predictions of all the decay modes are made based upon our preferred fit results and compared with data and those made by perturbative approaches. We have identified a few observables to be determined experimentally in order to discriminate among theory calculations.

We study Yangian-invariant deformations of scattering amplitudes in 4d $\mathcal{N}=4$ super Yang-Mills theory and 3d $\mathcal{N}=6$ Aharony-Bergman-Jafferis-Maldacena (ABJM) theory. In particular, we obtain the deformed Graßmannian integral for 4d $\mathcal{N}=4$ supersymmetric Yang-Mills theory, both in momentum and momentum-twistor space. For 3d ABJM theory, we initiate the study of deformed scattering amplitudes. We investigate general deformations of on-shell diagrams, and find the deformed Graßmannian integral for this theory. We furthermore introduce the algebraic R-matrix construction of deformed Yangian invariants for ABJM theory.

We study the dynamics of the Nambu-Goto membranes with cohomogeneity one symmetry, i.e., the membranes whose trajectories are foliated by homogeneous surfaces. It is shown that the equation of motion reduces to a geodesic equation on a certain manifold, which is constructed from the original spacetime and Killing vector fields thereon. A general method is presented for classifying the symmetry of cohomogeneity one membranes in a given spacetime. The classification is completely carried out in Minkowski spacetime. We analyze one of the obtained classes in depth and derive an exact solution.

The renormalization factors of local quark-bilinear operators are computed nonperturbatively for $N_f=3$ flavors of stout link nonperturbative clover (SLiNC) fermions, with emphasis on the various procedures for the chiral and continuum extrapolations. The simulations are performed at a lattice spacing $a=0.074\mathrm{fm}$, and for five values of the pion mass in the range of 290–465 MeV, allowing a safe and stable chiral extrapolation. Emphasis is given in the subtraction of the well-known pion pole which affects the renormalization factor of the pseudoscalar current. We also compute the inverse propagator and the Green’s functions of the local bilinears to one loop in perturbation theory. We investigate lattice artifacts by computing them perturbatively to second order as well as to all orders in the lattice spacing. The renormalization conditions are defined in the ${\mathrm{RI}}^{\prime }\text{−}\mathrm{MOM}$ scheme, for both the perturbative and nonperturbative results. The renormalization factors, obtained at different values of the renormalization scale, are translated to the $\overline{\mathrm{MS}}$ scheme and are evolved perturbatively to 2 GeV. Any residual dependence on the initial renormalization scale is eliminated by an extrapolation to the continuum limit. We also study the various sources of systematic errors. Particular care is taken in correcting the nonperturbative estimates by subtracting lattice artifacts computed to one-loop perturbation theory using the same action. We test two different methods, by subtracting either the $\mathcal{O}(g^2{a}^2)$ contributions, or the complete (all orders in $a$) one-loop lattice artifacts.

The general Ginzburg-Landau (GL) formulation of a holographic superconductor is developed near the transition temperature in the probe limit for two kinds of conformal dimension. elow the transition temperature, $T<T_c$, the order parameter scales with $\sqrt{1-\frac{T}{T_c}}$ as expected. The analytical expressions of GL free energy in the grand canonical ensemble and the canonical ensemble are derived and the gradient term is studied. Furthermore this scaling coefficient of the order parameter takes different values in the grand canonical ensemble and the canonical ensemble, suggesting the strong coupling nature of the boundary field theory of the superconductivity.

We perform a detailed semianalytical analysis of the electroweak phase transition (EWPT) property in the Next-to-Minimal Supersymmetric standard model, which serves as a good benchmark model in which the 126 GeV Higgs mixes with a singlet. In this case, a strongly first-order electroweak phase transition (SFOEWPT) is achieved by the tree-level effects, and the phase transition strength ${\gamma }_c$ is determined by the vacua energy gap at $T=0$. We make an anatomy of the energy gap at both tree level and loop level and extract out a dimensionless phase transition parameter $R_{\kappa }\equiv 4\kappa v_s/A_{\kappa }$, which can replace $A_{\kappa }$ in the parameterization and affect the light CP-odd/even Higgs spectra. We find that SFOEWPT only occurs in $R_{\kappa }\sim -1$ and positive $R_{\kappa }\lesssim \mathcal{O}(10)$, which in the non-PQ limit case would prefer either a relatively light CP-odd or CP-even Higgs boson $\sim (60,100)\mathrm{GeV}$, and therefore serves as a smoking gun signal and requires new search strategies at the LHC.

In this paper, static wormholes in the brane-world scenario are studied. We show that the existence of extra terms coming from the bulk help construct exact solutions that satisfy the null energy condition. Two important classes of solutions found earlier are analyzed in more depth in order to determine the conditions necessary for consistent solutions. Two new classes of solutions with different asymptotic behavior are also introduced. We focus on the conservation of the stress-energy tensor to achieve new solutions which have the important property of asymptotic flatness. Some main mathematical and physical properties of the solutions are addressed.

We consider the late-time one-loop quantum backreaction from inflationary fluctuations of a nonminimally coupled, massless scalar field. The scalar is assumed to be a spectator field in an inflationary model with a constant principal slow-roll $\epsilon$ parameter. We regulate the infrared by matching onto a pre-inflationary radiation era. We find a large late-time backreaction when the nonminimal coupling $\xi$ is negative (in which case the scalar exhibits a negative mass term during inflation). The one-loop quantum backreaction becomes significant today for moderately small nonminimal couplings, $\xi \sim -1/20$, and it changes sign (from negative to positive) at a recent epoch when inflation lasts not much longer than what is minimally required, $N\gtrsim 66$. Since currently we do not have a way of treating the classical fluid and the quantum backreaction in a self-consistent manner, we cannot say decidedly whether the backreaction from inflationary quantum fluctuations of a nonminimally coupled scalar can mimic dark energy.

The integrability conditions for the existence of a conformal Killing–Yano tensor of arbitrary order are worked out in all dimensions and expressed in terms of the Weyl tensor. As a consequence, the integrability conditions for the existence of a Killing–Yano tensor are also obtained. By means of such conditions, it is shown that in certain Einstein spaces one can use a conformal Killing–Yano tensor of order $p$ to generate a Killing–Yano tensor of order $(p-1)$. Finally, it is proved that in maximally symmetric spaces the covariant derivative of a Killing–Yano tensor is a closed conformal Killing–Yano tensor and that every conformal Killing–Yano tensor is uniquely decomposed as the sum of a Killing–Yano tensor and a closed conformal Killing–Yano tensor.

Searches for a stochastic gravitational-wave background (SGWB) using terrestrial detectors typically involve cross-correlating data from pairs of detectors. The sensitivity of such cross-correlation analyses depends, among other things, on the separation between the two detectors: the smaller the separation, the better the sensitivity. Hence, a colocated detector pair is more sensitive to a gravitational-wave background than a noncolocated detector pair. However, colocated detectors are also expected to suffer from correlated noise from instrumental and environmental effects that could contaminate the measurement of the background. Hence, methods to identify and mitigate the effects of correlated noise are necessary to achieve the potential increase in sensitivity of colocated detectors. Here we report on the first SGWB analysis using the two LIGO Hanford detectors and address the complications arising from correlated environmental noise. We apply correlated noise identification and mitigation techniques to data taken by the two LIGO Hanford detectors, H1 and H2, during LIGO’s fifth science run. At low frequencies, 40–460 Hz, we are unable to sufficiently mitigate the correlated noise to a level where we may confidently measure or bound the stochastic gravitational-wave signal. However, at high frequencies, 460–1000 Hz, these techniques are sufficient to set a 95% confidence level upper limit on the gravitational-wave energy density of $\mathrm{\Omega }(f)<7.7\times 10^{-4}(f/900\mathrm{Hz}{)}^3$, which improves on the previous upper limit by a factor of $\sim 180$. In doing so, we demonstrate techniques that will be useful for future searches using advanced detectors, where correlated noise (e.g., from global magnetic fields) may affect even widely separated detectors.

Photon-photon interactions, as described with the standard Heisenberg-Euler interaction, can transform plane polarization of the CMB into circular polarization, in the period right after last scattering. We estimate the distribution of the resulting circular polarization parameters, as constrained by confining observations to very small angular regions of large plane polarization, and find results of the order of $10^{-9}$ for the Stokes parameter $V$ in some of these regions.

We investigate gravitational effects on the so-called multiple point criticality principle (MPCP) at the Planck scale. The MPCP requires two degenerate vacua, whose necessary conditions are expressed by vanishing Higgs quartic coupling [$\lambda (M_{\mathrm{Pl}})=0$] and vanishing its $\beta$ function [${\beta }_{\lambda }(M_{\mathrm{Pl}})=0$]. We discuss a case that a specific form of gravitational corrections are assumed to contribute to $\beta$ functions of coupling constants [although it is accepted that gravitational corrections do not alter the running of the standard model (SM) couplings]. To satisfy the above two boundary conditions at the Planck scale, we find that the top pole mass and the Higgs mass should be $170.8\mathrm{GeV}\lesssim M_t\lesssim 171.7\mathrm{GeV}$ and $M_h=125.7\pm 0.4\mathrm{GeV}$, respectively, as well as include suitable magnitude of gravitational effects (a coefficient of gravitational contribution as $|a_{\lambda }|>2$). In this case, however, since the Higgs quartic coupling $\lambda$ becomes negative below the Planck scale, two vacua are not degenerate. We find that $M_h\gtrsim 131.5\mathrm{GeV}$ with $M_t\gtrsim 174\mathrm{GeV}$ is required by the realization of the MPCP. Therefore, the MPCP at the Planck scale cannot be realized in the SM, and also the SM with gravity since $M_h\gtrsim 131.5\mathrm{GeV}$ is experimentally ruled out.

We analyze the perturbative cusp and closed polygons of Wilson lines for massless gauge theories in coordinate space, and express them as exponentials of two-dimensional integrals. These integrals have geometric interpretations, which link renormalization scales with invariant distances.