We perform model-independent statistical analyses of three scenarios accommodating new physics (NP) in $\Delta F=2$ flavor-changing neutral current amplitudes. In a scenario in which NP in $B_d-{\overline{B}}_d$ mixing and $B_s-{\overline{B}}_s$ mixing is uncorrelated, we find the parameter point representing the standard model disfavored by 2.4 standard deviations. However, recent LHCb data on $B_s$ neutral meson mixing forbid a good accommodation of the DØ data on the semileptonic $CP$ asymmetry $A_{\mathrm{SL}}$. We introduce a fourth scenario with NP in both $M_{12}^{d,s}$ and ${\Gamma }_{12}^{d,s}$, which can accommodate all data. We discuss the viability of this possibility and emphasize the importance of separate measurements of the $CP$ asymmetries in semileptonic $B_d$ and $B_s$ decays. All results have been obtained with the CKMfitter analysis package, featuring the frequentist statistical approach and using Rfit to handle theoretical uncertainties.

In 2006, a simple extension of the standard model was proposed in which neutrinos obtain radiative Majorana masses at one-loop level from their couplings with dark matter, hence the term “scotogenic,” from the Greek “scotos” meaning darkness. Here an analogous mechanism for Dirac neutrino masses is discussed in a minimal model. In different ranges of the parameter space, various candidates for dark matter are possible. In particular, the lightest Dirac fermion which appears in the loop diagram generating neutrino mass can be a viable dark-matter candidate. Such a possibility does not exist for the Majorana case. Realistic neutrino mixing in the context of $A_4$ is discussed. A possible supersymmetric extension is also briefly discussed.

Using a sample of $(225.2\pm 2.8)\times {10}^6$ $J/\psi$ events collected with the BESIII detector, we present results of a study of $J/\psi \to \gamma \mathit{\Lambda }\overline{\mathit{\Lambda }}$ and report the first observation of the isospin violating decay $J/\psi \to \mathit{\Lambda }{\overline{\mathit{\Sigma }}}^0+\mathrm{c}.\mathrm{c}.$, in which ${\overline{\mathit{\Sigma }}}^0$ decays to $\gamma \overline{\mathit{\Lambda }}$. The measured branching fractions are $\mathcal{B}(J/\psi \to \overline{\mathit{\Lambda }}{\mathit{\Sigma }}^0)=(1.46\pm 0.11\pm 0.12)\times {10}^{-5}$ and $\mathcal{B}(J/\psi \to \mathit{\Lambda }{\overline{\mathit{\Sigma }}}^0)=(1.37\pm 0.12\pm 0.11)\times {10}^{-5}$. We search for $\mathit{\Lambda }(1520)\to \gamma \mathit{\Lambda }$ decay, and find no evident signal, and an upper limit for the product branching fraction $\mathcal{B}(J/\psi \to \mathit{\Lambda }\overline{\mathit{\Lambda }}(1520)+\mathrm{c}.\mathrm{c}.)\times \mathcal{B}(\mathit{\Lambda }(1520)\to \gamma \mathit{\Lambda })<4.1\times {10}^{-6}$ is set at the 90% confidence level. We also report the observation of ${\eta }_c\to \mathit{\Lambda }\overline{\mathit{\Lambda }}$ in $J/\psi \to \gamma {\eta }_c$, ${\eta }_c\to \mathit{\Lambda }\overline{\mathit{\Lambda }}$ and measure the branching fraction $\mathcal{B}({\eta }_c\to \mathit{\Lambda }\overline{\mathit{\Lambda }})=(1.16\pm 0.12(\mathrm{stat})\pm 0.19(\mathrm{syst})\pm 0.28(\mathrm{PDG}))\times {10}^{-3}$.

We point out that the extra neutralinos and charginos, generically appearing in a large class of $E_6$ inspired models, lead to distinctive signatures from gluino cascade decays involving longer decay chains, more visible transverse energy, softer jets, and leptons with higher multiplicity and less missing transverse energy than in the minimal supersymmetric standard model (MSSM). Although this makes the gluino harder to discover for certain types of conventional analysis, it leads to enhanced 3- and 4-lepton signatures, as compared to the MSSM, making the gluino more visible in these channels. After extensive scans over the parameter space, we focus on representative benchmark points for the two models, and perform a detailed Monte Carlo analysis of the 3-lepton channel at the Large Hadron Collider showing that $E_6$ inspired models are clearly distinguishable from the MSSM in gluino cascade decays.

Using data corresponding to an integrated luminosity of $1.3{\mathrm{fb}}^{-1}$, we observe a narrow mass state decaying into ${\rm Y}(1S)+\gamma$, where the ${\rm Y}(1S)$ meson is detected by its decay into a pair of oppositely charged muons, and the photon is identified through its conversion into an electron-positron pair. The significance of this observation is 5.6 standard deviations. The mass of the state is centered at $10.551\pm 0.014(\mathrm{stat})\pm 0.017(\mathrm{syst})\mathrm{GeV}/c^2$, which is consistent with that of the state recently observed by the ATLAS Collaboration.

Using samples of $102\times {10}^6$ ${\rm Y}(1S)$ and $158\times {10}^6$ ${\rm Y}(2S)$ events collected with the Belle detector, we study exclusive hadronic decays of these two bottomonium resonances to the three-body final states $\varphi K^{+}{K}^{-}$, $\omega {\pi }^{+}{\pi }^{-}$ and $K^{*0}(892)K^{-}{\pi }^{+}$, and to the two-body Vector-Tensor states ($\varphi f_2^{\prime }(1525)$, $\omega f_2(1270)$, $\rho a_2(1320)$ and $K^{*0}(892){\overline{K}}_2^{*0}(1430)$) and Axial-vector-Pseudoscalar ($K_1(1270{)}^{+}{K}^{-}$, $K_1(1400{)}^{+}{K}^{-}$ and $b_1(1235{)}^{+}{\pi }^{-}$) states. Signals are observed for the first time in the ${\rm Y}(1S)\to \varphi K^{+}{K}^{-}$, $\omega {\pi }^{+}{\pi }^{-}$, $K^{*0}{K}^{-}{\pi }^{+}$, $K^{*0}{K}_2^{*0}$ and ${\rm Y}(2S)\to \varphi K^{+}{K}^{-}$, $K^{*0}{K}^{-}{\pi }^{+}$ decay modes. Branching fractions are determined for all the processes, while 90% confidence level upper limits are established on the branching fractions for the modes with a statistical significance 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 OZI-suppressed bottomonium decays.

We find exact, analytic solutions of the Dirac equation for a charged, massless fermion in the background of a charged, dilatonic black hole in ${\mathrm{AdS}}_5$. The black hole descends from type IIB supergravity, where it describes D3-branes with equal angular momenta in two of the three independent planes of rotation orthogonal to the world-volume. The Green’s function near the Fermi surface for a strongly coupled fermionic system can be extracted holographically from an exact solution of the Dirac equation at zero frequency but nonzero momentum. There can be several Fermi momenta, and they take the form $k_F=q-n-1/2$ (in units of the chemical potential), where $q$ is the charge of the spinor, and $n$ is a non-negative integer that labels the Fermi surfaces. Much as for holographic Fermi surfaces based on the Reissner-Nordström-${\mathrm{AdS}}_5$ solution, the dispersion relation of the excitations near the Fermi surface is determined by the geometry close to the horizon, and one can obtain Fermi liquid, marginal Fermi liquid, and non-Fermi liquid behaviors depending on the value of $k_F$.

In this paper we study the non-Gaussian features of the primordial fluctuations in loop quantum cosmology with the inverse volume corrections. The detailed analysis is performed in the single field slow-roll inflationary models. However, our results reflect the universal characteristics of bispectrum in loop quantum cosmology. The main corrections to the scalar bispectrum come from two aspects: one is the modifications to the standard Bunch–Davies vacuum, and the other is the corrections to the background dependent variables, such as slow-roll parameters. Our calculations show that the loop quantum corrections make $f_{\mathrm{NL}}$ of the inflationary models increase 0.1%. Moreover, we find that two new shapes of non-Gaussian signal arise, which we name ${\mathcal{F}}_1$ and ${\mathcal{F}}_2$. The former gives a unique loop quantum feature, which is less correlated with the local, equilateral, and single types, while the latter is highly correlated with the local one.

We consider generic, or “dirty” (surrounded by matter), stationary rotating black holes with axial symmetry. The restrictions are found on the asymptotic form of metric in the vicinity of nonextremal, extremal and ultraextremal horizons, imposed by the conditions of regularity of increasing strength: boundedness on the horizon of the Ricci scalar, of scalar quadratic curvature invariants, and of the components of the curvature tensor in the tetrad attached to a falling observer. We show, in particular, that boundedness of the Ricci scalar implies the “rigidity” of the horizon’s rotation in all cases, while the finiteness of quadratic invariants leads to the constancy of the surface gravity. We discuss the role of quasiglobal coordinate $r$ that is emphasized by the conditions of regularity. Further restrictions on the metric are formulated in terms of subsequent coefficients of expansion of metric functions by $r$. The boundedness of the tetrad components of curvature tensor for an observer crossing the horizon is shown to lead in the horizon limit to diagonalization of the Einstein tensor in the frame of a zero angular momentum observer on a circular orbit (ZAMO frame) for horizons of all degrees of extremality.

We construct the perturbative solution of the charged black hole in the Kaluza-Klein spacetime with the matched asymptotic expansion method. The corrections to the thermodynamic variables are calculated up to the post-Newtonian order. We confirmed that the method can work very well in the Einstein-Maxwell theory.

We study the cosmological perturbations of the new bimetric gravity proposed by Hassan and Rosen [J. High Energy Phys. 02 (2012) 126] as a representation of massive gravity. The mass term in the model, in addition to ensuring ghost freedom for both metrics, causes the two scale factors to mix at the cosmological level, and this affects the cosmological perturbation of the model. We find two combinations corresponding to the entropy and adiabatic perturbations of the theory. In this sense we show that the adiabatic perturbations could be a source for the entropy perturbations. So in addition to the adiabatic perturbations, entropy perturbations can also be present in this theory. We also show that the adiabatic perturbations are not constant at the superhorizon scales, implying that the theory could not be used to describe the inflationary epoch, even if it can impose some corrections to the standard inflationary scenarios.

The Planck cluster catalog is expected to contain of order one thousand galaxy clusters, both newly discovered and previously known, detected through the Sunyaev-Zeldovich effect over the redshift range $0\lesssim z\lesssim 1$. Follow-up x-ray observations of a dynamically relaxed subsample of newly discovered Planck clusters will improve constraints on the dark energy equation of state found through measurement of the cluster gas mass fraction ($f_{\mathrm{gas}}$). In view of follow-up campaigns with XMM-Newton and Chandra satellites, we determine the optimal redshift distribution of a cluster sample to most tightly constrain the dark energy equation of state. The distribution is nontrivial even for the standard $w_0\mathrm{\text{−}}{w}_{\mathrm{a}}$ parametrization. We then determine how much the combination of expected data from the Planck satellite and $f_{\mathrm{gas}}$ data will be able to constrain the dark energy equation of state. Our analysis employs a Markov Chain Monte Carlo method as well as a Fisher Matrix analysis. With a suitably large program of observational time to observe only hot relaxed clusters, we find that these upcoming data would be able to improve the figure of merit by at least a factor two.

We show that a Dirac right-handed scalar neutrino can be dark matter (DM) as a weakly interacting massive particle in the neutrinophilic Higgs model. When the additional Higgs fields couple only to the leptonic sector through neutrino Yukawa couplings, the right number of relic density of DM can be obtained from thermal freeze-out of the DM annihilation into charged leptons and neutrinos. At present epoch, this tree-level annihilation into fermions is suppressed by the velocity of DM, and the one-loop annihilation cross section into $\gamma \gamma$ can be dominant because relevant coupling constants are different. Hence, the recently observed (tentative) gamma-ray line signal in the Fermi-Large Area Telescope can be naturally explained by the annihilation of right-handed sneutrino DM.

We study $SU(3)$-breaking effects in the neutral $B_d$-${\overline{B}}_d$ and $B_s$-${\overline{B}}_s$ systems with unquenched $N_f=2+1$ lattice quantum chromodynamics (QCD). We calculate the relevant matrix elements on the MILC collaboration’s gauge configurations with asqtad-improved staggered sea quarks. For the valence light-quarks ($u$, $d$, and $s$) we use the asqtad action, while for $b$ quarks we use the Fermilab action. We obtain $\xi =f_{B_s}\sqrt{B_{B_s}}/f_{B_d}\sqrt{B_{B_d}}=1.268\pm 0.063$. We also present results for the ratio of bag parameters $B_{B_s}/B_{B_d}$ and the ratio of Cabibbo-Kobayashi-Maskawa matrix elements $|V_{td}|/|V_{ts}|$. Although we focus on the calculation of $\xi$, the strategy and techniques described here will be employed in future extended studies of the $B$ mixing parameters $\Delta M_{d,s}$ and $\Delta {\Gamma }_{d,s}$ in the standard model and beyond.

It is argued that the ratio of the yield of pairs of charged and neutral $B^{(*)}$ mesons in the processes ${\rm Y}(5S)\to {\pi }^0+(B{\overline{B}}^{*}+\mathrm{c}.\mathrm{c}.)$ and ${\rm Y}(5S)\to {\pi }^0+B^{*}{\overline{B}}^{*}$ is very sensitive near the corresponding heavy meson threshold to the strong interaction between the mesons in the $I^G(J^P)=0^{-}(1^{+})$ channel due to significant isospin breaking by the Coulomb force. This channel, not readily accessible by other means, may contain near-threshold molecular meson-antimeson resonances—isoscalar analogs of the isovector states $Z_b(10610)$ and $Z_b(10650)$.

Extending previous work on two- and three-point functions, we study the four-point function and its conformal block structure in conformal quantum mechanics ${\mathrm{CFT}}_1$, which realizes the $SO(2,1)$ symmetry group. Conformal covariance is preserved even though the operators with which we work need not be primary and the states are not conformally invariant. We find that only one conformal block contributes to the four-point function. We describe some further properties of the states that we use and we construct dynamical evolution generated by the compact generator of $SO(2,1)$.

We investigate the relation between the Bogomol’nyi-Prasad-Sommerfeld (BPS) baby Skyrme model and its vector meson formulation, where the baby Skyrme term is replaced by a coupling between the topological current $B_{\mu }$ and the vector meson field ${\omega }_{\mu }$. The vector model still possesses infinitely many symmetries leading to infinitely many conserved currents which stand behind its solvability. It turns out that the similarities and differences of the two models depend strongly on the specific form of the potential. We find, for instance, that compactons (which exist in the BPS baby Skyrme model) disappear from the spectrum of solutions of the vector counterpart. Specifically, for the vector model with the old baby Skyrme potential we find that it has compacton solutions only provided that a delta function source term effectively screening the topological charge is inserted at the compacton boundary. For the old baby Skyrme potential squared we find that the vector model supports exponentially localized solitons, like the BPS baby Skyrme model. These solitons, however, saturate a BPS bound which is a nonlinear function of the topological charge and, as a consequence, higher solitons are unstable with respect to decay into smaller ones, which is at variance with the more conventional situation (a linear BPS bound and stable solitons) in the BPS baby Skyrme model.

The AdS/CFT correspondence allows us to map a dynamical cosmology to a dual quantum field theory living on the boundary of spacetime. Specifically, we study a five-dimensional model cosmology in type IIB supergravity, where the dual theory is an unstable deformation of $\mathcal{N}=4$ supersymmetric $SU(N)$ gauge theory on $\mathrm{IR}\times S^3$. A one-loop computation shows that the coupling governing the instability is asymptotically free, so quantum corrections cannot turn the potential around. The big crunch singularity in the bulk occurs when a boundary scalar field runs to infinity, in finite time. Consistent quantum evolution requires that we impose boundary conditions at infinite scalar field, i.e. a self-adjoint extension of the system. We find that quantum spreading of the homogeneous mode of the boundary scalar leads to a natural UV cutoff in particle production as the wave function for the homogeneous mode bounces back from infinity. However a perturbative calculation indicates that despite this, the logarithmic running of the boundary coupling governing the instability generally leads to significant particle production across the bounce. This prevents the wave packet of the homogeneous boundary scalar to return close to its initial form. Translating back to the bulk theory, we conclude that a quantum transition from a big crunch to a big bang is an improbable outcome of cosmological evolution in this class of five-dimensional models.

We use Monte Carlo simulation to probe the phase structure of a $SU(2)$ gauge theory containing $N_f$ Dirac fermion flavors transforming in the fundamental representation of the group and interacting through an additional four-fermion term. Pairs of physical flavors are implemented using the two tastes present in a reduced staggered fermion formulation of the theory. The resultant lattice theory is invariant under a set of shift symmetries which correspond to a discrete subgroup of the continuum chiral-flavor symmetry. The pseudoreal character of the representation guarantees that the theory has no sign problem. For the case of $N_f=4$ we observe a crossover in the behavior of the chiral condensate for strong four-fermi coupling associated with the generation of a dynamical mass for the fermions. At weak gauge coupling this crossover is consistent with the usual continuous phase transition seen in the pure (ungauged) Nambu–Jona-Lasinio model. However, if the gauge coupling is strong enough to cause confinement, we observe a much more rapid crossover in the chiral condensate consistent with a first order phase transition.

In this work we derive the expressions of the neutrino mean free path (MFP) and emissivity with non-Fermi-liquid corrections up to next-to-leading order (NLO) in degenerate quark matter. The calculation has been performed for both the absorption and the scattering processes. Subsequently the role of these NLO corrections on the cooling of the neutron star has been demonstrated. The cooling curve shows moderate enhancement compared to the leading order non-Fermi-liquid result. Although the overall correction to the MFP and emissivity are larger compared to the free Fermi gas, the cooling behavior is not altered significantly.