We analyze the impact of effective axial-vector coupling of the gluon on spin polarization observables in $t\overline{t}$ pair production at the LHC. Working at leading order in QCD, we compute the $t\overline{t}$ spin correlation and left-right spin asymmetry coefficients in the helicity basis in the laboratory frame as functions of the new physics scale $\Lambda$ associated with this coupling. We found that the $t\overline{t}$ invariant mass dependent asymmetries are more sensitive to the scale $\Lambda$ than the corresponding inclusive ones, in particular when suitable cuts selecting high $t\overline{t}$ invariant mass regions are imposed. In the context of this scenario, we show that the LHC has potential either to confirm or to rule out the Tevatron forward-backward top asymmetry anomaly by analyzing the $t\overline{t}$ spin correlation and left-right polarization asymmetries. On the other hand, stringent lower bound on the new physics scale $\Lambda$ can be set in this scenario if no significant deviations from the standard model predictions for those observables will be measured.

Interpretation of $CP$ violation measurements using charmonium decays, in both the ${\overline{B}}^0$ and ${\overline{B}}_s^0$ systems, can be subject to changes due to “penguin” type diagrams. These effects can be investigated using measurements of the Cabibbo-suppressed ${\overline{B}}^0\to J/\psi {\pi }^{+}{\pi }^{-}$ decays. The final state composition of this channel is investigated using a $1.0{\mathrm{fb}}^{-1}$ sample of data produced in 7 TeV $pp$ collisions at the LHC and collected by the LHCb experiment. A modified Dalitz-plot analysis is performed using both the invariant mass spectra and the decay angular distributions. An improved measurement of the ${\overline{B}}^0\to J/\psi {\pi }^{+}{\pi }^{-}$ branching fraction of $(3.97\pm 0.09\pm 0.11\pm 0.16)\times {10}^{-5}$ is reported where the first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty of the branching fraction of the decay $B^{-}\to J/\psi K^{-}$ used as a normalization channel. Significant production of $f_0(500)$ and $\rho (770)$ resonances is found in the substructure of the $J/\psi {\pi }^{+}{\pi }^{-}$ final state, and this indicates that they are viable final states for $CP$ violation studies. In contrast evidence for the $f_0(980)$ resonance is not found. This allows us to establish the first upper limit on the branching fraction product $\mathcal{B}({\overline{B}}^0\to J/\psi f_0(980))\times \mathcal{B}(f_0(980)\to {\pi }^{+}{\pi }^{-})<1.1\times {10}^{-6}$, leading to an upper limit on the absolute value of the mixing angle of the $f_0(980)$ with the $f_0(500)$ of less than 31°, both at 90% confidence level.

It has been a long-standing problem that the rare electromagnetic decay process $J/\psi \to 3\gamma$ is plagued with both large and negative radiative and relativistic corrections. To date it remains futile to make a definite prediction to confront with the branching fraction of $J/\psi \to 3\gamma$ recently measured by the CLEO-c and BESIII collaborations. In this work, we investigate the joint perturbative and relativistic correction [i.e., the $\mathcal{O}({\alpha }_s{v}^2)$ correction, where $v$ denotes the characteristic velocity of the charm quark inside the $J/\psi$] for this decay process, which turns out to be very significant. After incorporating the contribution from this new ingredient, with the reasonable choice of the input parameters, we are able to account for the measured decay rates in a satisfactory degree.

The conformal gravity fit to observed galactic rotation curves requires $\gamma >0$. On the other hand, the conventional method for light deflection by galaxies gives a negative contribution to the Schwarzschild value for $\gamma >0$, which is contrary to observation. Thus, it is very important that the contribution to bending should in principle be positive, no matter how small its magnitude is. Here we show that the Rindler-Ishak method gives a positive contribution to Schwarzschild deflection for $\gamma >0$, as desired. We also obtain the exact local coupling term derived earlier by Sereno. These results indicate that conformal gravity can potentially test well against all astrophysical observations to date.

In this paper, we discuss the time-dependent brane solutions in higher-dimensional supergravity theories. We particularly focus on the dynamical extensions of the intersecting brane solutions involving three branes. We also show that in the near-horizon limits, where the time dependence is negligible, these branes describe warped anti–de Sitter spacetimes as in the corresponding static solutions. We finally examine the lower-dimensional cosmological dynamics obtained after compactifications of the higher-dimensional solutions and show the solutions we have found give the four-dimensional universe with power-law expansion.

We study the one dimensional $s$-wave holographic superconductor by turning on the vector potential $A_x$ in the bulk, which behaves as $A_x=A_x^{(0)}\ln z+A_x^{(1)}$ on the boundary. By solving the model with fixed $A_x^{(0)}$, we find that if we identify the $A_x^{(0)}$ with the supercurrent $j_x$ of the holographic superconductor, the results agree with the Ginzburg-Landau theory. For example, $A_x^{(0)}$ will break the superconductivity, and the critical value of $A_x^{(0)}$ is proportional to $(T_c-T{)}^{3/2}$. In analogy, these results also tell us we should identify the constant term of the expansion of $A_t$ on the boundary as the chemical potential.

Fluid mechanics can be formulated on dynamical surfaces of arbitrary codimension embedded in a background space-time. This has been the main object of study of the blackfold approach in which the emphasis has primarily been on stationary fluid configurations. Motivated by this approach we show under certain conditions that a given stationary fluid configuration living on a dynamical surface of vanishing thickness and satisfying locally the first law of thermodynamics will behave like an elastic brane when the surface is subject to small deformations. These results, which are independent of the number of space-time dimensions and of the fluid arising from a gravitational dual, reveal the (electro)elastic character of (charged) black branes when considering extrinsic perturbations.

We study the shadow produced by a spinning Kaluza-Klein black hole in Einstein gravity coupled to a Maxwell field and a dilaton. The size and the shape of the shadow depend on the mass, the charge, and the angular momentum. We find that, for fixed values of these parameters, the shadow is slightly larger and less deformed than for its Kerr-Newman counterpart.

Several models of dark matter suggest the existence of hidden sectors consisting of $\mathrm{SU}(3{)}_C\times \mathrm{SU}(2{)}_L\times \mathrm{U}(1{)}_Y$ singlet fields. The interaction between the ordinary and hidden sectors could be transmitted by new Abelian ${\mathrm{U}}^{\prime }(1)$ gauge bosons $A^{\prime }$ (dark or hidden photons) mixing with ordinary photons. If such $A^{\prime }$’s have masses below the ${\pi }^0$ meson mass, they would be produced through $\gamma -A^{\prime }$ mixing in the ${\pi }^0\to \gamma \gamma$ decays and be observed via decays $A^{\prime }\to e^{+}{e}^{-}$. Using bounds from the SINDRUM experiment at the Paul Scherrer Institute that searched for an excess of $e^{+}{e}^{-}$ pairs in ${\pi }^{-}p$ interactions at rest, the area excluding the $\gamma -A^{\prime }$ mixing $ϵ\gtrsim {10}^{-3}$ for the $A^{\prime }$ mass region $25\lesssim M_{A^{\prime }}\lesssim 120\mathrm{MeV}$ is derived.

In this work, we report the determination of nonperturbative operator product expansion parameters from fits of continuum perturbation theory to the Landau gauge quark propagator. The propagators are computed numerically using lattice QCD with $N_f=2$ dynamical Wilson twisted mass fermions. We use four different values of the lattice spacing ranging from $a\approx 0.1\mathrm{fm}$ to $a\approx 0.05\mathrm{fm}$ as well as several quark masses per lattice spacing. This allows us to obtain continuum results for the chiral condensate and the up/down quark mass extrapolated to the physical point. The main results are the average up/down quark mass $m_q^{\overline{\mathrm{MS}}}(2\mathrm{GeV})=3.0(4)(2)\mathrm{MeV}$ at the physical point and $⟨\overline{\psi }\psi {⟩}^{\overline{\mathrm{MS}}}(2\mathrm{GeV})=-(299(26)(29)\mathrm{MeV}{)}^3$ in the chiral limit. We have also studied nonperturbative contaminations of our results at small values of the momenta, which are often interpreted as the contribution of the gluon condensate $⟨A^2⟩$. We do see contributions from such terms, which are, however, not stable over the order in perturbation theory.

We discuss dense states of QCD matter formed in high-energy hadronic and heavy-ion collisions from the point of view of statistical physics of nonequilibrium processes. For this sake, we first propose a formulation of the dynamical entropy of dense QCD states in the “saturation regime” leading to a color glass condensate. The statistical physics description amounts to describing the modification of the color correlation length with energy as a compression process for which nonequilibrium thermodynamic properties are applicable. We derive an expression of the dynamical entropy in terms of the rapidity evolution of the unintegrated gluon distributions in the colliding nuclei, verifying suitable positivity and irreversibility properties. We extend this approach to the initial preequilibrium (glasma) state of a heavy-ion collision. It allows for a definition of the initial entropy before the evolution towards the hydrodynamic regime as a function of the glasma correlation length and an overlap parameter characterizing the low-momentum spectrum of the glasma state. This initial entropy, by extension to the $\mathcal{N}=4$ Super Yang-Mills theory, is then matched as the key input parameter to the strong coupling evaluation of thermalization towards the hydrodynamic regime based on the AdS/CFT correspondence. It thus allows one to cast a bridge between the weak and strong coupling phases of a heavy-ion reaction.

We propose to measure the threshold lepton asymmetry, that is the forward-backward asymmetry of the charged lepton in $t\overline{t}$ events near the production threshold. At threshold, top quark pairs are produced in an s-wave. Angular momentum conservation then implies that the top spins equal the spin of the initial state which—in the case of quarks—is uniquely fixed by the chirality of the initial quarks. Thus, measuring final-state top spins determines the chirality of the quarks which produced them. Information about the top spins can be extracted by measuring the angular distribution of the charged lepton in semileptonic or dileptonic decays of the top pair. One such distribution, the threshold lepton asymmetry, vanishes in tree-level QCD but is nonzero if new physics modifies the relative contribution of right-handed and left-handed quarks to top pair production. This is interesting because realistic models addressing the anomalous $t\overline{t}$ asymmetry have chiral couplings to light quarks. Models with identical $t\overline{t}$ asymmetries at the Tevatron can be distinguished by their threshold lepton asymmetries, which range between plus and minus 25% in realistic models.

The noncommutative standard model apparently violates the Lorentz symmetry. We compare the Lorentz-violating terms in the Higgs sector of the noncommutative standard model with their counterparts in the standard model extension. We show that the Lorentz-violating parameters in the Higgs sector can be expressed directly in terms of the noncommutative parameter without any background field. The absence of the background field enhances the obtained bounds on the noncommutative parameter from the standard model extension.

We derive a constraint on patchy screening of the cosmic microwave background from inhomogeneous reionization using off-diagonal $TB$ and $TT$ correlations in WMAP-7 temperature/polarization data. We interpret this as a constraint on the rms optical-depth fluctuation $\Delta \tau$ as a function of a coherence multipole $L_C$. We relate these parameters to a comoving coherence scale, of bubble size $R_C$, in a phenomenological model where reionization is instantaneous but occurs on a crinkly surface, and also to the bubble size in a model of “Swiss cheese” reionization where bubbles of fixed size are spread over some range of redshifts. The current WMAP data are still too weak, by several orders of magnitude, to constrain reasonable models, but forthcoming Planck and future EPIC data should begin to approach interesting regimes of parameter space. We also present constraints on the parameter space imposed by the recent results from the EDGES experiment.

We investigate three dimensional anti–de sitter $({\mathrm{AdS}}_3)/{\mathrm{CFT}}_2$ correspondence in three-dimensional supergravity. We construct a current for the general coordinate invariance and that for local supersymmetry via the covariant approach. The Hamiltonian and supercharge are well defined in terms of vielbein and spin connection. After discussing the asymptotic supersymmetry group at the boundary of $\mathrm{Ad}{\mathrm{S}}_3$ geometry, we show that there exists a direct product of Virasoro algebras at the boundary. We also show that one of them is extended to super Virasoro algebra.

Gravitational radiation reaction affects the dynamics of gravitationally bound binary systems. Here we focus on the leading “tail” term which modifies binary dynamics at fourth post-Newtonian order, as first computed by Blanchet and Damour. We reproduce this result using effective field theory techniques in the framework of the Lagrangian formalism suitably extended to include dissipation effects. We recover the known logarithmic tail term, consistently with the recent interpretation of the logarithmic tail term in the mass parameter, as a renormalization group effect of the Bondi mass of the system.

We study the relation between minimal dilatonic gravity (MDG) and $f(R)$ theories of gravity and establish strict conditions for their global equivalence. Such equivalence takes place only for a certain class of cosmological potentials, dubbed here “withholding potentials,” since they prevent change of the sign of the dilaton $\Phi$. The withholding property ensures the attractive character of gravity, as well as absence of ghosts and a tachyon in the gravi-dilaton sector and yields certain asymptotic of the functions $f(R)$. Large classes of withholding cosmological potentials and functions $f(R)$ are found and described in detail. The particle content of the gravi-dilaton sector is found using perturbation theory around the de Sitter vacuum of MDG. Two phenomena, scalaron waves and induction of gravitational waves by the scalaron field, are discussed using the derived wave equations for MDG scalaron and graviton in the de Sitter background. Seemingly, the MDG and $f(R)$ theories offer a unified description of dark energy and dark matter.

Assuming that the recently discovered particle at LHC is the standard theory (ST) Higgs boson, we compare the ST predictions of $M_W$ and ${sin}^2{\theta }_{\mathrm{eff}}^{\mathrm{lept}}$ with the experimental values of these basic observables. While the ${sin}^2{\theta }_{\mathrm{eff}}^{\mathrm{lept}}$ prediction is in excellent agreement with its experimental value, that of $M_W$ shows a $1.33\sigma$ deviation. Implications of these comparisons for possible future developments at LHC and a future GigaZ linear collider are briefly discussed. It is also pointed out that these comparisons are consistent with the conjecture that the newly discovered particle is indeed the ST Higgs boson.

Transition form factors of ${\pi }^0$, $\eta$, ${\eta }^{\prime }$ mesons are investigated by means of the anomaly sum rule—an exact nonperturbative relation which follows from the dispersive representation of the axial anomaly. Considering the problem of contributions of operators originated from a non-(local) operator product expansion, we found that they are required by the available set of experimental data, including the most recent data from the Belle Collaboration (which, if taken alone, can be described without such contributions, although are compatible with them). In this approach, we analyzed the experimental data on $\eta$ and ${\eta }^{\prime }$ meson transition form factors and obtained the constraints on the decay constants and mixing parameters.

We revisit the role of color mixing in the quark model calculation of tetraquark states, and compare simple pairwise potentials to more elaborate string models with three- and four-body forces. We attempt to disentangle the improved dynamics of confinement from the approximations made in the treatment of the internal color degrees of freedom.