We propose a possible explanation for the recent diphoton excess reported by ATLAS and CMS Collaborations at around a 750 GeV diphoton invariant mass within the framework of the $E_6$-motivated alternative left-right symmetric model, which is capable of addressing the $B$ decay anomalies in the flavor sector, the $eejj$ and $e{\cancel{p}}_{T}jj$ excesses reported by CMS in run 1 of the LHC, and high-scale leptogenesis. We find that gluon-gluon fusion can give the observed production rate of the 750 GeV resonance, $\tilde{n}$, through a loop of scalar leptoquarks (${\tilde{h}}^{(c)}$) with a mass below a few TeV range, while $\tilde{n}$ can subsequently decay into a $\gamma \gamma$ final state via loops of ${\tilde{h}}^{(c)}$ and ${\tilde{E}}^{(c)}$. Interestingly, the slepton $({\tilde{E}}^{(c)})$ loop can enhance the diphoton branching ratio significantly to successfully explain the observed cross section of the diphoton signal.

Supergravity grand unified models (SUGRA GUTs) are highly motivated and allow for a high degree of electroweak naturalness when the superpotential parameter $\mu \sim 100–300\mathrm{GeV}$ (preferring values closer to 100 GeV). We first illustrate that models with radiatively driven naturalness enjoy a generalized focus-point behavior wherein all soft terms are correlated instead of just scalar masses. Next, we generate spectra from four SUGRA GUT archetypes: 1. $SO(10)$ models where the Higgs doublets live in different ten-dimensional irreducible representations (irreps), 2. models based on $SO(10)$ where the Higgs multiplets live in a single ten-dimensional irrep but with $D$-term scalar mass splitting, 3. models based on $SU(5)$, and 4. a more general SUGRA model with 12 independent parameters. Electroweak naturalness implies for all models a spectrum of light Higgsinos with $m_{{\tilde{W}}_1,{\tilde{Z}}_{1,2}}\lesssim 300\mathrm{GeV}$ and gluinos with $m_{\tilde{g}}\lesssim 2–4\mathrm{TeV}$. However, masses and mixing in the third generation sfermion sector differ distinctly between the models. These latter differences would be most easily tested at a linear $e^{+}{e}^{-}$ collider with $\sqrt{s}\sim$ multi-TeV scale but measurements at a 50–100 TeV hadron collider are also possible.

Using ($2+1$)-flavor lattice QCD, we compute the 10 form factors describing the ${\mathrm{\Lambda }}_b\to \mathrm{\Lambda }$ matrix elements of the $b\to s$ vector, axial vector, and tensor currents. The calculation is based on gauge field ensembles generated by the RBC and UKQCD Collaborations with a domain-wall action for the $u$, $d$, and $s$ quarks and the Iwasaki gauge action. The $b$ quark is implemented using an anisotropic clover action, tuned nonperturbatively to the physical point, and the currents are renormalized with a mostly nonperturbative method. We perform simultaneous chiral, continuum, and kinematic extrapolations of the form factors through modified $z$ expansions. Using our form factor results, we obtain precise predictions for the ${\mathrm{\Lambda }}_b\to \mathrm{\Lambda }(\to p^{+}{\pi }^{-}){\mu }^{+}{\mu }^{-}$ differential branching fraction and angular observables in the Standard Model.

The widths of the strong decays $Z_c^{+}(3900)\to J/\psi {\pi }^{+}$ and $Z_c^{+}(3900)\to {\eta }_c{\rho }^{+}$ are calculated. To this end, the mass and decay constant of the exotic $Z_c^{+}(3900)$ state are computed by means of a two-point sum rule. The obtained results are then used to calculate the strong couplings $g_{Z_{c}J/\psi \pi }$ and $g_{Z_c{\eta }_c\rho }$ employing QCD sum rules on the light cone supplied by a technique of the soft-meson approximation. We compare our predictions on the mass and decay widths with available experimental data and other theoretical results.

Updated standard model predictions for $D_{(s)}\to P{l}^{+}{l}^{-}$, $l=e$, $\mu$, $P=\pi$, $K$ and inclusive decays are presented. Model-independent constraints on $|\mathrm{\Delta }C|=|\mathrm{\Delta }U|=1$ Wilson coefficients are worked out. New physics (NP) opportunities do arise in semileptonic branching ratios for very large couplings only, however, are not excluded outside the resonance regions yet. The NP potential of resonance-assisted $CP$ asymmetries and angular observables is worked out. Predictions are given for leptoquark models and include lepton flavor-violating and dineutrino decays. Whether NP can be seen depends on flavor patterns, and vice versa.

A search for Lorentz- and $CPT$-violating signals in the double beta decay spectrum of ${}^{136}\mathrm{Xe}$ has been performed using an exposure of $100\mathrm{kg}·\mathrm{yr}$ with the EXO-200 detector. No significant evidence of the spectral modification due to isotropic Lorentz-violation was found, and a two-sided limit of $-2.65\times {10}^{-5}\mathrm{GeV}<{â}_{\mathrm{of}}^{(3)}<7.60\times {10}^{-6}\mathrm{GeV}$ (90% C.L.) is placed on the relevant coefficient within the Standard-Model Extension (SME). This is the first experimental study of the effect of the SME-defined oscillation-free and momentum-independent neutrino coupling operator on the double beta decay process.

Vectorlike quarks, usually dubbed top partners, are a common presence in composite Higgs models. Being composite objects, their mass is expected to be of the order of their inverse size, that is the condensation scale of the new strong interactions. Light top partners, while not being a generic prediction, are, however, often considered in phenomenological models. We suggest that their lightness may be due to the matching of global ’t Hooft anomalies of the underlying theory. We check this mechanism in explicit models, showing that, in one case, composite fermions with the quantum numbers of the top quark obtain a mass which is controlled by a soft breaking term and can be made parametrically small.

We study Bogomol’nyi-Prasad-Sommerfield (BPS) excitations in M5-M2-brane configurations with a compact transverse direction, which are also relevant for type IIa and IIb little string theories. These configurations are dual to a class of toric elliptically fibered Calabi-Yau manifolds $X_N$ with manifest $SL(2,\mathbb{Z})\times SL(2,\mathbb{Z})$ modular symmetry. They admit two dual gauge theory descriptions. For both, the nonperturbative partition function can be written as an expansion of the topological string partition function of $X_N$ with respect to either of the two modular parameters. We analyze the resulting BPS-counting functions in detail and find that they can be fully constructed as linear combinations of the BPS-counting functions of M5-M2-brane configurations with noncompact transverse directions. For certain M2-brane configurations, we also find that the free energies in the two dual theories agree with each other, which points to a new correspondence between instanton and monopole configurations. These results are also a manifestation of T-duality between type IIa and IIb little string theories.

Combining new gravitational waveforms derived by long-term (14 to 16 orbit) numerical-relativity simulations with waveforms by an effective-one-body (EOB) formalism for coalescing binary neutron stars, we construct hybrid waveforms and estimate the measurability for the dimensionless tidal deformability of the neutron stars, $\mathrm{\Lambda }$, by advanced gravitational-wave detectors. We focus on the equal-mass case with the total mass $2.7M_{\odot }$. We find that for an event at a hypothetical effective distance of $D_{\mathrm{eff}}=200\mathrm{Mpc}$, the distinguishable difference in the dimensionless tidal deformability will be $\approx 100$, 400, and 800 at $1\sigma$, $2\sigma$, and $3\sigma$ levels, respectively, for Advanced LIGO. If the true equation of state is stiff and the typical neutron-star radius is $R\gtrsim 13\mathrm{km}$, our analysis suggests that the radius will be constrained within $\approx 1\mathrm{km}$ at $2\sigma$ level for an event at $D_{\mathrm{eff}}=200\mathrm{Mpc}$. On the other hand, if the true equation of state is soft and the typical neutron-star radius is $R\lesssim 12\mathrm{km}$, it will be difficult to narrow down the equation of state among many soft ones, although it is still possible to discriminate the true one from stiff equations of state with $R\gtrsim 13\mathrm{km}$. We also find that gravitational waves from binary neutron stars will be distinguished from those from spinless binary black holes at more than $2\sigma$ level for an event at $D_{\mathrm{eff}}=200\mathrm{Mpc}$. The validity of the EOB formalism, Taylor-T4, and Taylor-F2 approximants as the inspiral waveform model is also examined.

In metric-affine theories of gravity such as the C-theories, the spacetime connection is associated to a metric that is nontrivially related to the physical metric. In this article, such theories are rewritten in terms of a single metric, and it is shown that they can be recast as effectively nonlocal gravity. With some assumptions, known ghost-free theories with nonsingular and cosmologically interesting properties may be recovered. Relations between different formulations are analyzed at both perturbative and nonperturbative levels, taking carefully into account subtleties with boundary conditions in the presence of integral operators in the action, and equivalences between theories related by nonlocal redefinitions of the fields are verified at the level of equations of motion. This suggests a possible geometrical interpretation of nonlocal gravity as an emergent property of non-Riemannian spacetime structure.

Following our previous papers concerning the quantization of the vacuum Bianchi-IX model within or beyond the Born-Oppenheimer and adiabatic approximation, we develop a more elaborate analysis of the dynamical properties of the model based on the vibronic approach utilized in molecular physics. As in the previous papers, we restrict our approach to the harmonic approximation of the anisotropy potential in order to obtain resoluble analytical expressions.

Thermal inflation is an attractive idea to dilute cosmic density of unwanted particles such as moduli fields which cause cosmological difficulties. However, it also dilutes preexisting baryon asymmetry and some viable baryogenesis is necessary for a cosmologically consistent scenario. We investigate whether the Affleck-Dine mechanism can produce baryon asymmetry enough to survive after the dilution in gauge-mediated SUSY breaking models. Flat directions generally cannot provide such huge baryon number because of Q-ball formation. We show that although the $L{H}_u$ flat direction is special in terms of having $\mu$-term which prevents Q-ball formation, it cannot explain the observed baryon asymmetry either.

We study the correlation between the value of the triple Higgs coupling and the nature of the electroweak phase transition. We use an effective potential approach, including higher order, nonrenormalizable terms coming from integrating out new physics. We show that if only the dimension six operators are considered, large positive deviations of the triple Higgs coupling from its standard model (SM) value are predicted in the regions of parameter space consistent with a strong first order electroweak phase transition. We also show that at higher orders sizable and negative deviations of the triple Higgs coupling may be obtained, and the sign of the corrections tends to be correlated with the order of the phase transition. We also consider a singlet extension of the SM, which allows us to establish the connection with the effective field theory approach and analyze the limits of its validity. Furthermore, we study how to probe the triple Higgs coupling from the double Higgs production at the LHC. We show that selective cuts in the invariant mass of the two Higgs bosons should be used, to maximize the sensitivity for values of the triple Higgs coupling significantly different from the standard model one.

We compute and analyze correlation functions in the isovector vector channel at vanishing spatial momentum across the deconfinement phase transition in lattice QCD. The simulations are carried out at temperatures $T/T_c=0.156$, 0.8, 1.0, 1.25 and 1.67 with $T_c\simeq 203\mathrm{MeV}$ for two flavors of Wilson-Clover fermions with a zero-temperature pion mass of $\simeq 270\mathrm{MeV}$. Exploiting exact sum rules and applying a phenomenologically motivated Ansatz allows us to determine the spectral function $\rho (\omega ,T)$ via a fit to the lattice correlation function data. From these results we estimate the electrical conductivity across the deconfinement phase transition via a Kubo formula and find evidence for the dissociation of the $\rho$ meson by resolving its spectral weight at the available temperatures. We also apply the Backus-Gilbert method as a model-independent approach to this problem. At any given frequency, it yields a local weighted average of the true spectral function. We use this method to compare kinetic theory predictions and previously published phenomenological spectral functions to our lattice study.

We explore the quark mass effects on inclusive hadron production in proton-nucleus collisions at high energies. We consider two processes. First, we compute the single inclusive cross section for production of hadrons with open heavy flavor in the proton forward direction at leading order. Next, in the same kinematics, we calculate the heavy-quark contribution to single inclusive production of light or unidentified hadrons at next-to-leading order. For both studies, we exploit the hybrid formalism; that is, the collinear factorization on the proton side while high-density and high-energy effects are resummed on the side of the nucleus.

In this paper, we discuss the new hard-pole contribution to the $P_{h\perp }$-weighted single-transverse spin asymmetry in semi-inclusive deep inelastic scattering. We perform the complete next-to-leading-order calculation of the $P_{h\perp }$-weighted cross section and show that the new hard-pole contribution is required in order to obtain the complete evolution equation for the Qiu-Sterman function derived by different approaches.

We analyze transverse momentum ($Q_T$) resummation of a colorless final state, e.g. Higgs production in gluon fusion or the production of a lepton pair via the Drell-Yan mechanism, in the limit where the invariant mass of the final state is much less than the center-of-mass energy, i.e. $Q^2\ll s$. We show how the traditional resummation of logarithms of $Q_T/Q$ can be supplemented with the resummation of the leading logarithmic contributions at small $x=Q^2/s$ and we compute the necessary ingredients to perform such joint resummation.

Amplitude models are applied to studies of resonance structure in $D^0\to K_S^0{K}^{-}{\pi }^{+}$ and $D^0\to K_S^0{K}^{+}{\pi }^{-}$ decays using $pp$ collision data corresponding to an integrated luminosity of $3.0{\mathrm{fb}}^{-1}$ collected by the LHCb experiment. Relative magnitude and phase information is determined, and coherence factors and related observables are computed for both the whole phase space and a restricted region of $100\mathrm{MeV}/c^2$ around the $K^{*}(892{)}^{\pm }$ resonance. Two formulations for the $K\pi S$-wave are used, both of which give a good description of the data. The ratio of branching fractions $\mathcal{B}(D^0\to K_S^0{K}^{+}{\pi }^{-})/\mathcal{B}(D^0\to K_S^0{K}^{-}{\mathrm{\pi }}^{+})$ is measured to be $0.655\pm 0.004(\mathrm{stat})\pm 0.006(\mathrm{syst})$ over the full phase space and $0.370\pm 0.003(\mathrm{stat})\pm 0.012(\mathrm{syst})$ in the restricted region. A search for $CP$ violation is performed using the amplitude models and no significant effect is found. Predictions from SU(3) flavor symmetry for $K^{*}(892)K$ amplitudes of different charges are compared with the amplitude model results.

We study the thermodynamic properties of matter at vanishing temperature for nonextreme values of the isospin chemical potential and of the strange quark chemical potential. From the leading-order pressure obtained by maximizing the static chiral Lagrangian density, we derive a simple expression for the equation of state in the pion condensed phase and in the kaon condensed phase. We find an analytical expression for the maximum of the ratio between the energy density and the Stefan-Boltzmann energy density and for the isospin chemical potential at the peak, both in good agreement with lattice simulations of quantum chromodynamics. We speculate on the location of the crossover from the Bose-Einstein condensate state to the Bardeen-Cooper-Schrieffer state by a simple analysis of the thermodynamic properties of the system. For ${\mu }_I\gtrsim 2m_{\pi }$, the leading-order chiral perturbation theory breaks down; for example, it underestimates the energy density of the system and leads to a wrong asymptotic behavior.

We study entanglement entropy for parity-violating (time-reversal breaking) quantum field theories on ${\mathbb{R}}^{1,2}$ in the presence of a domain wall between two distinct parity-odd phases. The domain wall hosts a $1+1$-dimensional conformal field theory (CFT) with nontrivial chiral central charge. Such a CFT possesses gravitational anomalies. It has been shown recently that, as a consequence, its intrinsic entanglement entropy is sensitive to Lorentz boosts around the entangling surface. Here, we show using various methods that the entanglement entropy of the three-dimensional bulk theory is also sensitive to such boosts owing to parity-violating effects, and that the bulk response to a Lorentz boost precisely cancels the contribution coming from the domain wall CFT. We argue that this can naturally be interpreted as entanglement inflow (i.e., inflow of entanglement entropy analogous to the familiar Callan-Harvey effect) between the bulk and the domain-wall, mediated by the low-lying states in the entanglement spectrum. These results can be generally applied to $2+1$-d topological phases of matter that have edge theories with gravitational anomalies, and provide a precise connection between the gravitational anomaly of the physical edge theory and the low-lying spectrum of the entanglement Hamiltonian.