The phase structure of the two-flavor Polyakov-loop extended Nambu-Jona-Lashinio model is explored at finite temperature and imaginary chemical potential with a particular emphasis on the confinement-deconfinement transition. We point out that the confined phase is characterized by a $\cos 3{\mu }_I/T$ dependence of the chiral condensate on the imaginary chemical potential while in the deconfined phase this dependence is given by $\cos {\mu }_I/T$ and accompanied by a cusp structure induced by the $Z(3)$ transition. We demonstrate that the phase structure of the model strongly depends on the choice of the Polyakov loop potential $\mathcal{U}$. Furthermore, we find that by changing the four fermion coupling constant $G_s$, the location of the critical end point of the deconfinement transition can be moved into the real chemical potential region. We propose a new parameter characterizing the confinement-deconfinement transition.

Understanding and identifying ditau jets—jets consisting of pairs of tau particles—can be of crucial importance and may even turn out to be a necessity if the Higgs boson decays dominantly to new light scalars which, on the other hand, decay to tau pairs. As often seen in various models beyond the standard model such as in the next-to-minimal supersymmetric standard model, Higgs portals, etc., the lightness of these new states ensures their large transverse momenta and, as a consequence, the collinearity of their decay products. We show that the nonstandard signatures of these objects, which can easily be missed by standard analysis techniques, can be superbly exploited in an analysis based on subjet observables. When combined with additional selection strategies, this analysis can even facilitate an early discovery of the Higgs boson. To be specific, a light Higgs can be found with $S/\sqrt{B}\gtrsim 5$ from $\mathcal{L}\simeq 12{\mathrm{fb}}^{-1}$ of data. We combine all these observables into a single discriminating likelihood that can be employed toward the construction of a realistic and standalone ditau tagger.

This article provides an in-depth look at hadron high-energy scattering by using gravity dual descriptions of strongly coupled gauge theories. Just like deeply inelastic scattering (DIS) and deeply virtual Compton scattering (DVCS) serve as clean experimental probes into nonperturbative internal structure of hadrons, elastic scattering amplitude of a hadron and a (virtual) photon in gravity dual can be exploited as a theoretical probe. Since the scattering amplitude at sufficiently high energy (small Bjorken $x$) is dominated by parton contributions ($=\mathrm{\text{Pomeron contributions}}$) even in strong coupling regime, there is a chance to learn a lesson for generalized parton distribution (GPD) by using gravity dual models. We begin with refining derivation of the Brower–Polchinski–Strassler–Tan (BPST) Pomeron kernel in gravity dual, paying particular attention to the role played by the complex spin variable $j$. The BPST Pomeron on warped spacetime consists of a Kaluza–Klein tower of 4D Pomerons with nonlinear trajectories, and we clarify the relation between Pomeron couplings and the Pomeron form factor. We emphasize that the saddle-point value $j^{*}$ of the scattering amplitude in the complex $j$-plane representation is a very important concept in understanding qualitative behavior of the scattering amplitude. The total Pomeron contribution to the scattering is decomposed into the saddle-point contribution and at most a finite number of pole contributions, and when the pole contributions are absent (which we call saddle-point phase), kinematical variable $(q,x,t)$-dependence of $\ln (1/q)$ evolution and $\ln (1/x)$ evolution parameters ${\gamma }_{\mathrm{eff}}$ and ${\lambda }_{\mathrm{eff}}$ in DIS and $t$-slope parameter $B$ of DVCS in HERA experiment are all reproduced qualitatively in gravity dual. All of these observations shed a new light on modeling of GPD. Straightforward application of those results to other hadron high-energy scattering is also discussed.

We present a calculation of the Nucleon and Delta excited state spectra on dynamical anisotropic clover lattices. A method for operator construction is introduced that allows for the reliable identification of the continuum spins of baryon states, overcoming the reduced symmetry of the cubic lattice. Using this method, we are able to determine a spectrum of single-particle states for spins up to and including $J=\frac{7}{2}$, of both parities, the first time this has been achieved in a lattice calculation. We find a spectrum of states identifiable as admixtures of $SU(6)\otimes O(3)$ representations and a counting of levels that is consistent with the nonrelativistic $qqq$ constituent quark model. This dense spectrum is incompatible with quark-diquark model solutions to the “missing resonance problem” and shows no signs of parity doubling of states.

We estimate the long-distance contribution to the width difference of the $B_s\mathrm{\text{−}}{\overline{B}}_s$ system, based mainly on two-body $D_s^{(*)}{\overline{D}}_s^{(*)}$ modes and three-body $D_s^{(*)}{\overline{D}}^{(*)}{\overline{K}}^{(*)}$ modes (and their CP conjugates). Some higher $c\overline{s}$ resonances are also considered. The contribution to $\Delta {\Gamma }_s/{\Gamma }_s$ by two-body modes is $(10.2\pm 3.0)\%$, slightly smaller than the short-distance result of $(13.3\pm 3.2)\%$. The contribution to $\Delta {\Gamma }_s/{\Gamma }_s$ by $D_{s0}^{*}(2317)$, $D_{s1}(2460)$, and $D_{s1}(2536)$ resonances is negligible. For the three-body $D_s^{(*)}{\overline{D}}^{(*)}{\overline{K}}^{(*)}$ modes, we adopt the factorization formalism and model the form factors with off-shell $D_s^{(*)}$ poles, the $D_{sJ}(2700)$ resonance, and nonresonant contributions. These three-body modes can arise through current-produced or transition diagrams, but only SU(3)-related $D_{u,d}^{(*)}{\overline{D}}^{(*)}\overline{K}$ modes from the current diagram have been measured so far. The pole model results for $D_{u,d}^{*}{\overline{D}}^{(*)}\overline{K}$ agree well with the data, while $D_{u,d}{\overline{D}}^{(*)}\overline{K}$ rates agree with the data only within a factor of 2 to 3. All measured $D_{u,d}^{(*)}{\overline{D}}^{(*)}\overline{K}$ rates can be reproduced by including nonresonant contributions. The total $\Delta {\Gamma }_s/{\Gamma }_s$ obtained is $(16.7\pm 8.5)\%$, which agrees with the short-distance result within uncertainties. For illustration, we also demonstrate the effect of $D_{sJ}(2700)$ in modes with $D^{(*)}{K}^{*}$. In all scenarios, the total $\Delta {\Gamma }_s/{\Gamma }_s$ remain consistent with the short-distance result. Our results indicate that (a) the operator product expansion in the short-distance picture is a valid assumption, (b) approximating the $B_s\to D_s^{(*)}{\overline{D}}_s^{(*)}$ decays to saturate $\Delta {\Gamma }_s$ has a large correction, (c) the effect of three-body modes cannot be neglected, and (d) in addition to the $D_s$ and $D_s^{*}$ poles, the $D_{sJ}(2700)$ resonance also plays an important role in three-body modes. Future experiments are necessary to improve the estimation of $\Delta {\Gamma }_s$ from the long-distance point of view.

We consider the $U(1)$ charged sector of ABJM theory at finite temperature, which corresponds to the Reissner-Nordstrom AdS black hole in the dual type IIA supergravity description. Including back-reaction to the bulk geometry, we show that phase transitions occur to a broken phase where $SU(4)$ R-symmetry of the field theory is broken spontaneously by the condensation of dimension one or two operators. We construct the composite operators out of fields in ABJM theory and describe the phase transition with the dual gravity solutions. We show numerically and analytically that the relevant critical exponents for the dimension one operator agree precisely with those of mean field theory in the strongly coupled regime of the large $N$ planar limit.

The recently discovered high-energy transient Swift $J164449.3+573451$ (Sw $J1644+57$) is thought to arise from the tidal disruption of a passing star by a dormant massive black hole. Modeling of the broadband emission suggests the presence of a powerful relativistic jet, which contributes dominantly to the observed x-ray emission. Here we suggest that protons can be accelerated to ultrahigh energies by internal shocks occurring in the jets, but their flux is insufficient to account for the observed flux of ultrahigh-energy cosmic rays. High-energy protons can produce $\sim 0.1–10\mathrm{PeV}$ neutrinos through photomeson interactions with x-ray photons. The large x-ray fluence ($7\times {10}^{-4}\mathrm{erg}{\mathrm{cm}}^{-2}$) and high photopion efficiency, together with the insignificant cooling of secondary mesons, result in bright neutrino emission expected from Sw $J1644+57$ if the jet composition is matter-dominated. One to several neutrinos may be detected by a ${\mathrm{Km}}^3$-scale detector from one tidal disruption event similar to Sw $J1644+57$, thereby providing a powerful probe of the composition of the jets.

Little Higgs theory naturally predicts a light Higgs boson whose most important discovery channel at the LHC is the diphoton signal $pp\to h\to \gamma \gamma$. In this work, we perform a comparative study for this signal in some typical little Higgs models, namely, the littlest Higgs model, two littlest Higgs models with T-parity (named LHT-I and LHT-II), and the simplest little Higgs models. We find that compared with the standard model prediction, the diphoton signal rate is always suppressed and the suppression extent can be quite different for different models. The suppression is mild ($\lesssim 10\%$) in the littlest Higgs model but can be quite severe ($\simeq 90\%$) in other three models. This means that discovering the light Higgs boson predicted by the little Higgs theory through the diphoton channel at the LHC will be more difficult than discovering the standard model Higgs boson.

We study the azimuthal asymmetries in proton-proton Drell-Yan processes with one incident proton being transversely or longitudinally polarized. We consider particularly the asymmetries contributed by the leading-twist chiral-odd quark distributions. We analyze the asymmetries with $\sin (2\varphi +{\varphi }_S)$ and $\sin (2\varphi -{\varphi }_S)$ modulations in transverse single polarized $p^{\uparrow }p$ Drell-Yan and $\sin 2\varphi$ asymmetries in longitudinal single polarized $p^{\to }p$ Drell-Yan at the Relativistic Heavy Ion Collider, the Japan Proton Accelerator Research Complex, E906 (Fermi Lab), and the Nuclotron-based Ion Collider Facility (Joint Institute for Nuclear Research). We show that the measurements of the asymmetries in those facilities can provide valuable information of the chiral-odd structure of the nucleon both in the valence and sea regions.

We present searches for rare or forbidden charm decays of the form $X_c^{+}\to h^{\pm }{\ell }^{\mp }{\ell }^{(\prime )+}$, where $X_c^{+}$ is a charm hadron ($D^{+}$, $D_s^{+}$, or ${\Lambda }_c^{+}$), $h^{\pm }$ is a pion, kaon, or proton, and ${\ell }^{(\prime )\pm }$ is an electron or muon. The analysis is based on $384{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ annihilation data collected at or close to the ${\rm Y}(4S)$ resonance with the BABAR detector at the SLAC National Accelerator Laboratory. No significant signal is observed for any of the 35 decay modes that are investigated. We establish 90% confidence-level upper limits on the branching fractions between $1\times {10}^{-6}$ and $44\times {10}^{-6}$ depending on the channel. In most cases, these results represent either the first limits or significant improvements on existing limits for the decay modes studied.

We suggest a new possibility for ATLAS and CMS to explore the $t\overline{t}$ forward-backward asymmetry measured at the Tevatron, by attempting to reconstruct $t\overline{t}$ events, with one of the tops decaying semileptonically in the central region ($|\eta |<2.5$) and the other decaying hadronically in the forward region ($|\eta |>2.5$). For several models which give comparable Tevatron signals, we study the charge asymmetry at the LHC as a function of cuts on $|\eta |$ and on the $t\overline{t}$ invariant mass, $m_{t\overline{t}}$. We show that there is an interesting complementarity between cuts on $|\eta |$ and $m_{t\overline{t}}$ to suppress the dominant and symmetric $gg\to t\overline{t}$ rate, and different combinations of cuts enhance the distinguishing power between models. This complementarity is likely to hold in other new physics scenarios as well, which affect the $t\overline{t}$ cross section, so it motivates extending $t\overline{t}$ reconstruction to higher $|\eta |$.

Using a sample of $158\times {10}^6$ ${\rm Y}(2S)$ events collected with the Belle detector, charmonium and charmoniumlike states with even charge parity are searched for in ${\rm Y}(2S)$ radiative decays. No significant ${\chi }_{cJ}$ or ${\eta }_c$ signal is observed, and the following upper limits at 90% confidence level (C. L.) are obtained: $\mathcal{B}({\rm Y}(2S)\to \gamma {\chi }_{c0})<1.0\times {10}^{-4}$, $\mathcal{B}({\rm Y}(2S)\to \gamma {\chi }_{c1})<3.6\times {10}^{-6}$, $\mathcal{B}({\rm Y}(2S)\to \gamma {\chi }_{c2})<1.5\times {10}^{-5}$, and $\mathcal{B}({\rm Y}(2S)\to \gamma {\eta }_c)<2.7\times {10}^{-5}$. No significant signal of any charmoniumlike state is observed, and we obtain the limits $\mathcal{B}({\rm Y}(2S)\to \gamma X(3872))\times \mathcal{B}(X(3872)\to {\pi }^{+}{\pi }^{-}J/\psi )<0.8\times {10}^{-6}$, $\mathcal{B}({\rm Y}(2S)\to \gamma X(3872))\times \mathcal{B}(X(3872)\to {\pi }^{+}{\pi }^{-}{\pi }^{0}J/\psi )<2.4\times {10}^{-6}$, $\mathcal{B}({\rm Y}(2S)\to \gamma X(3915))\times \mathcal{B}(X(3915)\to \omega J/\psi )<2.8\times {10}^{-6}$, $\mathcal{B}({\rm Y}(2S)\to \gamma Y(4140))\times \mathcal{B}(Y(4140)\to \varphi J/\psi ))<1.2\times {10}^{-6}$, and $\mathcal{B}({\rm Y}(2S)\to \gamma X(4350))\times \mathcal{B}(X(4350)\to \varphi J/\psi ))<1.3\times {10}^{-6}$ at 90% C. L.

Recently there has been progress on the calculation of three-point functions with two “heavy” operators via semiclassical methods. We extend this analysis to the case of the Lunin-Maldacena background and examine the suggested procedure for several simple string solutions. By making use of AdS/CFT duality, we derive the relevant correlation functions of operators belonging to the dual $\mathcal{N}=1$ superconformal gauge theory, and recover an important relation connecting the dimensions of heavy states and the structure constants.

It has been argued that in noncommutative field theories, the sizes of physical objects cannot be taken smaller than an “elementary length” related to noncommutativity parameters. By gauge covariantly extending field equations of noncommutative $U(1{)}_{\star }$ theory to cover the presence of external sources, we find electric and magnetic fields produced by an extended static charge. We find that such a charge, apart from being an ordinary electric monopole, is also a magnetic dipole. By writing off the existing experimental clearance in the value of the lepton magnetic moments for the present effect, we get the bound on noncommutativity at the level of ${10}^4\mathrm{TeV}$.

We study how the dynamical vector degree of freedom in modified gravity affects the CMB $B$-mode polarization in terms of the Einstein-aether theory. In this theory, vector perturbations can be generated from inflation, which can grow on superhorizon scales in the subsequent epochs and thereby leaves imprints on the CMB $B$-mode polarization. We derive the linear perturbation equations in a covariant formalism, and compute the CMB $B$-mode polarization using the CAMB code modified so as to incorporate the effect of the aether vector field. We find that the amplitude of the $B$-mode signal from the aether field can be larger than the contribution from the inflationary gravitational waves for reasonable initial conditions and for a viable range of model parameters, in which perturbation modes propagate superluminally. We also give an analytic argument explaining the shape of the spectrum based on the tight coupling approximation.

Symmetry restoration in a theory of a self-interacting charged scalar field at finite temperature and in the presence of an external magnetic field is examined. The effective potential is evaluated nonperturbatively in the context of the optimized perturbation theory method. It is explicitly shown that in all ranges of the magnetic field, from weak to large fields, the phase transition is second order and that the critical temperature increases with the magnetic field. In addition, we present an efficient way to deal with the sum over the Landau levels, which is of interest especially in the case of working with weak magnetic fields.

The advent of precise measurements of the CMB anisotropies has motivated correspondingly precise calculations of the cosmic recombination history. Cosmic recombination proceeds far out of equilibrium because of a “bottleneck” at the $n=2$ level of hydrogen: atoms can only reach the ground state via slow processes—two-photon decay or Lyman-$\alpha$ resonance escape. However, even a small primordial abundance of molecules could have a large effect on the interline opacity in the recombination epoch and lead to an additional route for hydrogen recombination. Therefore, this paper computes the abundance of the ${\mathrm{H}}_2$ molecule during the cosmic recombination epoch. Hydrogen molecules in the ground electronic levels ${\mathrm{X}}^1{\Sigma }_g^{+}$ can either form from the excited ${\mathrm{H}}_2$ electronic levels ${\mathrm{B}}^1{\Sigma }_u^{+}$ and ${\mathrm{C}}^1{\Pi }_u$ or through the charged particles ${\mathrm{H}}_2^{+}$, ${\mathrm{HeH}}^{+}$, and ${\mathrm{H}}^{-}$. We follow the transitions among all of these species, resolving the rotational and vibrational sublevels. Since the energies of the ${\mathrm{X}}^1{\Sigma }_g^{+}-{\mathrm{B}}^1{\Sigma }_u^{+}$ (Lyman band) and ${\mathrm{X}}^1{\Sigma }_g^{+}-{\mathrm{C}}^1{\Pi }_u$ (Werner band) transitions are near the Lyman-$\alpha$ energy, the distortion of the CMB spectrum caused by escaped H Lyman-line photons accelerates both the formation and the destruction of ${\mathrm{H}}_2$ due to this channel relative to the thermal rates. This causes the populations of ${\mathrm{H}}_2$ molecules in ${\mathrm{X}}^1{\Sigma }_g^{+}$ energy levels to deviate from their thermal equilibrium abundances. We find that the resulting ${\mathrm{H}}_2$ abundance is ${10}^{-17}$ at $z=1200$ and ${10}^{-13}$ at $z=800$, which is too small to have any significant influence on the recombination history.

Apparent channel-dependent violations of the Okubo-Zwieg-Iizuka (OZI) rule in nucleon-antinucleon annihilation reactions in the presence of an intrinsic strangeness component in the nucleon are discussed. Admixture of $s\overline{s}$ quark pairs in the nucleon wave function enables the direct coupling to the $\varphi$-meson in the annihilation channel without violating the OZI rule. Three forms are considered in this work for the strangeness content of the proton wave function, namely, the $uud$ cluster with a $s\overline{s}$ sea-quark component, kaon-hyperon clusters based on a simple chiral quark model, and the pentaquark picture $uuds\overline{s}$. Nonrelativistic quark model calculations reveal that the strangeness magnetic moment ${\mu }_s$ and the strangeness contribution to the proton spin ${\sigma }_s$ from the first two models are consistent with recent experimental data, where ${\mu }_s$ and ${\sigma }_s$ are negative. For the third model, the $uuds$ subsystem with the configurations $[31{]}_{FS}[211{]}_F[22{]}_S$ and $[31{]}_{FS}[31{]}_F[22{]}_S$ leads to negative values of ${\mu }_s$ and ${\sigma }_s$. With effective quark line diagrams incorporating the ${}^{3}P_0$ model, we give estimates for the branching ratios of the annihilation reactions at rest $p\overline{p}\to \varphi X$ ($X={\pi }^0$, $\eta$, ${\rho }^0$, $\omega$). Results for the branching ratios of $\varphi X$ production from atomic $p\overline{p}$ $s$-wave states are for the first and third model found to be strongly channel dependent, in good agreement with measured rates.

Recent experimental results from the CDF collaboration which study the top forward-backward asymmetry have strengthened the case that new physics is playing a role in $t\overline{t}$ production. Here, we propose a set of measurements, built from the charged lepton kinematics in semileptonic and fully leptonic $t\overline{t}$ events, designed to further probe the underlying causes of this asymmetry both at the Tevatron and at the LHC. Using a set of conservative reference models, we find that measurements of the charged lepton asymmetry, top polarization, and $t\overline{t}$ spin correlation can establish the existence of new physics and distinguish between competing models both at the Tevatron and the LHC. At the Tevatron, discrimination between models is possible at the $3\sigma$ level. At the LHC, we demonstrate that a top forward-backward asymmetry can be established at $\gtrsim 3\sigma$ in the first $\sim 5{\mathrm{fb}}^{-1}$ of data and show how competing explanations can be further disentangled.

We search for resonant production of $t\overline{t}$ pairs in $4.8{\mathrm{fb}}^{-1}$ integrated luminosity of $p\overline{p}$ collision data at $\sqrt{s}=1.96\mathrm{TeV}$ in the $\mathrm{\text{lepton}}+\mathrm{\text{jets}}$ decay channel, where one top quark decays leptonically and the other hadronically. A matrix-element reconstruction technique is used; for each event a probability density function of the $t\overline{t}$ candidate invariant mass is sampled. These probability density functions are used to construct a likelihood function, whereby the cross section for resonant $t\overline{t}$ production is estimated, given a hypothetical resonance mass and width. The data indicate no evidence of resonant production of $t\overline{t}$ pairs. A benchmark model of leptophobic $Z^{\prime }\to t\overline{t}$ is excluded with $m_{Z^{\prime }}<900\mathrm{GeV}/{\mathrm{c}}^2$ at 95% confidence level.