One-loop effects of Standard Model (SM) extensions comprising universal extra dimensions are essential as a consequence of Kaluza-Klein (KK) parity conservation, for they represent the very first presumable virtual effects on low-energy observables. In this paper, we calculate the one-loop $CP$-even contributions to the SM $WW\gamma$ and $WWZ$ gauge couplings produced by the KK excited modes that stand for the dynamical variables of the effective theory emerged from a generalization of the SM to five dimensions, in which the extra dimension is assumed to be universal, after compactification. The employment of a covariant gauge-fixing procedure that removes gauge invariance associated to gauge KK excited modes, while keeping electroweak gauge symmetry manifest, is a main feature of this calculation, which is performed in the Feynman-’t Hooft gauge and yields finite results that consistently decouple for a large compactification scale. After numerical evaluation, our results are comparable with the one-loop SM contributions and well within the reach of a next linear collider.

We explore the phenomenological implications on charged lepton flavor violating (LFV) processes from slepton flavor mixing within the Minimal Supersymmetric Standard Model (MSSM). We work under the model-independent hypothesis of general flavor mixing in the slepton sector, being parametrized by a complete set of dimensionless ${\delta }_{ij}^{AB}$ ($A$, $B=L$, $R$; $i$, $j=1$, 2, 3, $i\ne j$) parameters. The present upper bounds on the most relevant LFV processes, together with the requirement of compatibility in the choice of the MSSM parameters with the recent LHC and $(g-2{)}_{\mu }$ data, lead to updated constraints on all slepton flavor mixing parameters. A comparative discussion of the most effective LFV processes to constrain the various generation mixings is included.

We determine the prospects for direct and indirect detection of thermal relic neutralinos in supersymmetric theories with multi-TeV squarks and sleptons. We consider the concrete example of the focus point region of minimal supergravity, but our results are generically valid for all models with decoupled scalars and mixed Bino-Higgsino or Higgsino-like dark matter. We determine the parameter space consistent with a 125 GeV Higgs boson including 3-loop corrections in the calculation of the Higgs mass. These corrections increase $m_h$ by 1–3 GeV, lowering the preferred scalar mass scale and decreasing the fine-tuning measure in these scenarios. We then systematically examine prospects for dark matter direct and indirect detection. Direct detection constraints do not exclude these models, especially for $\mu <0$. At the same time, the scenario generically predicts spin-independent signals just beyond current bounds. We also consider indirect detection with neutrinos, gamma rays, antiprotons, and antideuterons. Current IceCube neutrino constraints are competitive with direct detection, implying bright prospects for complementary searches with both direct and indirect detection.

We present a lattice QCD calculation of form factors for the decay ${\Lambda }_b\to p{\mu }^{-}{\overline{\nu }}_{\mu }$, which is a promising channel for determining the Cabibbo-Kobayashi-Maskawa matrix element $|V_{ub}|$ at the Large Hadron Collider. In this initial study we work in the limit of static $b$ quarks, where the number of independent form factors reduces to two. We use dynamical domain-wall fermions for the light quarks, and perform the calculation at two different lattice spacings and at multiple values of the light-quark masses in a single large volume. Using our form factor results, we calculate the ${\Lambda }_b\to p{\mu }^{-}{\overline{\nu }}_{\mu }$ differential decay rate in the range $14{\mathrm{GeV}}^2\le q^2\le q_{\max }^2$, and obtain the integral ${\int }_{14{\mathrm{GeV}}^2}^{q_{\max }^2}[\mathrm{d}\Gamma /\mathrm{d}{q}^2]\mathrm{d}{q}^2/|V_{ub}{|}^2=15.3\pm 4.2{\mathrm{ps}}^{-1}$. Combined with future experimental data, this will give a novel determination of $|V_{ub}|$ with about 15% theoretical uncertainty. The uncertainty is dominated by the use of the static approximation for the $b$ quark, and can be reduced further by performing the lattice calculation with a more sophisticated heavy-quark action.

Multihadron operators are crucial for reliably extracting the masses of excited states lying above multihadron thresholds in lattice QCD Monte Carlo calculations. The construction of multihadron operators with significant coupling to the lowest-lying multihadron states of interest involves combining single hadron operators of various momenta. The design and implementation of large sets of spatially-extended single-hadron operators of definite momentum and their combinations into two-hadron operators are described. The single hadron operators are all assemblages of gauge-covariantly-displaced, smeared quark fields. Group-theoretical projections onto the irreducible representations of the symmetry group of a cubic spatial lattice are used in all isospin channels. Tests of these operators on ${24}^3\times 128$ and ${32}^3\times 256$ anisotropic lattices using a stochastic method of treating the low-lying modes of quark propagation which exploits Laplacian Heaviside quark-field smearing are presented. The method provides reliable estimates of all needed correlations, even those that are particularly difficult to compute, such as $\eta \eta \to \eta \eta$ in the scalar channel, which involves the subtraction of a large vacuum expectation value. A new glueball operator is introduced, and the evaluation of the mixing of this glueball operator with a quark-antiquark operator, $\pi \pi$, and $\eta \eta$ operators is shown to be feasible.

We provide a compendium of results at the level of matrix elements for a systematic study of dark matter scattering and annihilation. We identify interactions that yield spin-dependent and spin-independent scattering and specify whether the interactions are velocity and/or momentum suppressed. We identify the interactions that lead to $s$-wave or $p$-wave annihilation, and those that are chirality suppressed. We also list the interaction structures that can interfere in scattering and annihilation processes. Using these results, we point out situations in which deviations from the standard lore are obtained.

Forward-backward asymmetries $A_{\mathrm{FB}}^t$ and $A_{\mathrm{FB}}^{\ell }$ are observed in the top-quark $t$ rapidity distribution and in the rapidity distribution of charged leptons $\ell$ from top-quark decay at the Tevatron proton-antiproton collider, and a charge asymmetry $A_{\mathrm{C}}$ is seen in proton-proton collisions at the Large Hadron Collider (LHC). In this paper, we update our previous studies of the Tevatron asymmetries using the most recent data. We provide expectations for $A_{\mathrm{C}}$ at the LHC based first on simple extrapolations from the Tevatron, and second based on new physics models that can explain the Tevatron asymmetries. We examine the relationship of the two asymmetries $A_{\mathrm{FB}}^t$ and $A_{\mathrm{FB}}^{\ell }$. We show their connection through the ($V-A$) spin correlation between the charged lepton and the top quark with different polarization states. We show that the ratio of the two asymmetries provides independent insight into the physics interpretation of the top-quark asymmetry. We emphasize the value of the measurement of both asymmetries, and we conclude that a model which produces more right-handed than left-handed top quarks is suggested by the present Tevatron data.

The initial data on the production and decay of the Higgs boson reported significant deviations from the Standard Model (SM) expectations, prompting much speculation about its couplings to the other particles. Although the latest data has veered towards conformity with the SM, there is yet room for a sizable deviation from the SM values of the coupling of the Higgs boson with $t\overline{t}$, and to a smaller extent, of that with $W^{+}{W}^{-}$ and $ZZ$. Keeping the fluid nature of the data in mind, this opens up an interesting avenue to explore regarding unitarity of gauge boson scattering and the stability of the electroweak vacuum in the presence of anomalous couplings. We show that, for some typical benchmark points, unitarity in gauge boson scattering breaks down between 1 and 10 TeV. We also show that if there are no new light degrees of freedom, the Higgs quartic coupling becomes negative at around the same point, making the electroweak vacuum unstable. Thus, some new ultraviolet completing new physics is demanded at that scale to cancel both these anomalous behaviours if such deviations from the SM couplings are indeed established.

A search for new particles that decay into top quark pairs ($t\overline{t}$) is performed with the ATLAS experiment at the LHC using an integrated luminosity of $4.7{\mathrm{fb}}^{-1}$ of proton–proton ($pp$) collision data collected at a center-of-mass energy $\sqrt{s}=7\mathrm{TeV}$. In the $t\overline{t}\to WbWb$ decay, the lepton plus jets final state is used, where one $W$ boson decays leptonically and the other hadronically. The $t\overline{t}$ system is reconstructed using both small-radius and large-radius jets, the latter being supplemented by a jet substructure analysis. A search for local excesses in the number of data events compared to the Standard Model expectation in the $t\overline{t}$ invariant mass spectrum is performed. No evidence for a $t\overline{t}$ resonance is found and 95% credibility-level limits on the production rate are determined for massive states predicted in two benchmark models. The upper limits on the cross section times branching ratio of a narrow $Z^{\prime }$ resonance range from 5.1 pb for a boson mass of 0.5 TeV to 0.03 pb for a mass of 3 TeV. A narrow leptophobic topcolor $Z^{\prime }$ resonance with a mass below 1.74 TeV is excluded. Limits are also derived for a broad color-octet resonance with $\Gamma /m=15.3\%$. A Kaluza–Klein excitation of the gluon in a Randall–Sundrum model is excluded for masses below 2.07 TeV.

Using samples of 102 million ${\rm Y}(1S)$ and 158 million ${\rm Y}(2S)$ events collected with the Belle detector, we study exclusive hadronic decays of these two bottomonium resonances to $K_S^0{K}^{+}{\pi }^{-}$ and charge-conjugate (c.c.) states, ${\pi }^{+}{\pi }^{-}{\pi }^0{\pi }^0$, and ${\pi }^{+}{\pi }^{-}{\pi }^0$, and to the two-body Vector-Pseudoscalar ($K^{*}(892{)}^0{\overline{K}}^0+\mathrm{c}.\mathrm{c}.$, $K^{*}(892{)}^{-}{K}^{+}+\mathrm{c}.\mathrm{c}.$, $\omega {\pi }^0$, and $\rho \pi$) final states. For the first time, signals are observed in the modes ${\rm Y}(1S)\to K_S^0{K}^{+}{\pi }^{-}+\mathrm{c}.\mathrm{c}.$, ${\pi }^{+}{\pi }^{-}{\pi }^0{\pi }^0$, and ${\rm Y}(2S)\to {\pi }^{+}{\pi }^{-}{\pi }^0{\pi }^0$, and evidence is found for the modes ${\rm Y}(1S)\to {\pi }^{+}{\pi }^{-}{\pi }^0$, $K^{*}(892{)}^0{\overline{K}}^0+\mathrm{c}.\mathrm{c}.$, and ${\rm Y}(2S)\to K_S^0{K}^{+}{\pi }^{-}+\mathrm{c}.\mathrm{c}.$ Branching fractions are measured for all the processes, while 90% confidence level upper limits on the branching fractions are also set for the modes with a statistical significance of less than $3\sigma$. The ratios of the branching fractions of ${\rm Y}(2S)$ and ${\rm Y}(1S)$ decays into the same final state are used to test a perturbative QCD prediction for Okubo-Zweig-Iizuka-suppressed bottomonium decays.

We add smeared D0 charges to the D4 background and discuss the Sakai-Sugimoto model under this background. The corresponding gauge theory is in a state with an expectation value of $⟨\mathrm{tr}(F_{\mu \nu }{\tilde{F}}^{\mu \nu })⟩$. The D8-branes go less deep than in the original S-S model and massless Goldstones are still found in the spectrum. The effects of this condensate on the meson spectra, pion decay constant, and couplings of the vector mesons and Goldstones in this background state are then investigated.

Results from spectral geometry such as Weyl’s formula can be used to relate the thermodynamic properties of a free massless field to the spatial manifold on which it is defined. We begin by calculating the free energy in two cases: manifolds posessing a boundary and spheres. The subextensive contributions allow us to test the Cardy-Verlinde formula and offer a new perspective on why it only holds in a free theory if one allows for a change in the overall coefficient. After this we derive an expression for the density of states that takes the form of a Taylor series. This series leads to an improvement over known results when the area of the manifold’s boundary is nonzero but much less than the appropriate power of its volume.

In dipole-dipole scattering at large rapidity $\chi =\ln (s/s_0)$, the induced instanton on the string world sheet carries entropy ${\mathbf{S}}_k=2({\alpha }_{\mathbf{P}k}-1)\chi$, with ${\alpha }_{\mathbf{P}k}-1$ the Pomeron intercept for a dipole source of N-ality $k$. We argue that this entropy is released promptly over a time $t_R\approx ({\mathbf{b}}_{\perp }/\chi {)}^3/(4{\alpha }^{\prime })$, with ${\alpha }^{\prime }/2$ the Pomeron slope and ${\mathbf{b}}_{\perp }$ the impact parameter. This stringy entropy may explain the $3/2$ jump in the total charged multiplicities at about ten participants reported over a wide range of collider energies by PHOBOS. We predict the charged multiplicities in $pp$, $pA$ and central $AA$ collisions at LHC.

We reformulate quantum tunneling in a multidimensional system where the tunneling sector is nonlinearly coupled to oscillators. The WKB wave function is explicitly constructed under the assumption that the system was in the ground state before tunneling. We find that the quantum state after tunneling can be expressed in the language of the conventional in-in formalism. Some implications of the result to cosmology are discussed.

We consider in this work the electromagnetic current for a system composed of two charged bosons and show that it has a structure of many bodies even in the impulse approximation, when described in the light-front time $x^{+}$. In terms of the two-body component for the bound state, the current contains two-body operators. We consider the photon interacting with two bosons and the process of pair creation connected to this interaction, interpreting it as a zero mode contribution to the current and discuss the consequences of this pair creation to the components of currents in the light front.

We study the imaginary part of the Lorentzian gravitational action for bounded regions, as described in previous work [Y. Neiman, arXiv:1301.7041]. By comparison to a Euclidean calculation, we explain the agreement between the formula for this imaginary part and the formula for black hole entropy. We also clarify the topological structure of the imaginary part in Lovelock gravity. We then evaluate the action’s imaginary part for some special regions. These include cylindrical slabs spanning the exterior of a stationary black hole spacetime and “maximal diamonds” in various symmetric spacetimes, as well as local near-horizon regions. In the first setup, the black hole’s entropy and conserved charges contribute to the action’s imaginary and real parts, respectively. In the other two setups, the imaginary part coincides with the relevant entropy.

We study the effects of screened modified gravity of the $f(R)$, dilaton and symmetron types on structure formation, from the quasilinear to the nonlinear regime, using semianalytical methods. For such models, where the range of the new scalar field is typically within the Mpc range and below in the cosmological context, nonlinear techniques are required to understand the deviations of the power spectrum of the matter density contrast compared to the $\Lambda \mathrm{CDM}$ template. This is nowadays commonly tackled using extensive $N$-body simulations. Here we present new results combining exact perturbation theory at the one-loop level (and a partial resummation of the perturbative series) with a halo model. The former allows one to extend the linear perturbative analysis up to $k\lesssim 0.15h{\mathrm{Mpc}}^{-1}$ at the perturbative level while the latter leads to a reasonable, up to a few percent, agreement with numerical simulations for $k\lesssim 3h{\mathrm{Mpc}}^{-1}$ for large-curvature $f(R)$ models, and $k\lesssim 1h{\mathrm{Mpc}}^{-1}$ for dilatons and symmetrons, at $z=0$. We also discuss how the behaviors of the perturbative expansions and of the spherical collapse differ for $f(R)$, dilaton, and symmetron models.

We present a simple extension of the standard model that gives rise to baryogenesis and has a dark matter candidate of $\mathcal{O}(\mathrm{GeV})$ mass. A minimal set of new fields required for baryogenesis includes two $\mathcal{O}(\mathrm{TeV})$ colored scalars and a singlet fermion. The fermion also becomes a viable dark matter candidate when its is nearly degenerate in mass with the proton. Dark matter and baryon asymmetry are produced from the decay of heavy scalars, which can lead to a natural explanation of the baryon-dark matter coincidence problem. The dark matter candidate escapes direct and indirect detection, but can be probed at the LHC. The supersymmetric extension of this model is straightforward and leads to a multicomponent dark matter scenario, which improves the direct and indirect detection prospects.

There are many mixing schemes based upon flavor symmetries that predict a vanishing ${\theta }_{13}$. These mixing schemes need corrections or modifications to account for recent experimental measurements of nonzero ${\theta }_{13}$. We propose new parametrizations for the lepton mixing matrix to quantify the minimal modifications needed in these mixing schemes. The parametrizations can be factorized in two parts: $U_0(a,b)$ and $R(\theta ,\varphi )$. The first factor can be viewed as a zeroth order mixing matrix coming from some flavor symmetry. It reproduces the popular mixing schemes based upon flavor symmetries for suitable values of $a$ and $b$. The second factor can be interpreted as a minimal modification to the mixing matrix and is responsible for nonzero ${\theta }_{13}$, nonmaximal ${\theta }_{23}$ and $CP$ violation. We also find the experimentally allowed parameter space for the parameters $a$ and $b$ and compare it with the symmetry based values for these parameters.

Studying the hidden-charm dipion decays of the charmoniumlike state $Y(4360)$, we show that there exist charged charmoniumlike structures near $D{\overline{D}}^{*}$ and $D^{*}{\overline{D}}^{*}$ thresholds in the $J/\psi {\pi }^{+}$, $\psi (2S){\pi }^{+}$, and $h_c(1P){\pi }^{+}$ invariant mass spectra of the corresponding hidden-charm dipion decays of $Y(4360)$ using the initial single pion emission mechanism. We suggest further experimental study on these predicted charged enhancement structures, especially by BESIII, Belle, and the forthcoming BelleII.