Planned cosmic microwave background (CMB) experiments will improve what we know about neutrino physics, inflation, and dark energy. The low level of noise, together with improved angular resolution, will increase the signal-to-noise ratio of the CMB polarized data as well as the reconstructed lensing potential of large scale structure. Projected constraints on cosmological parameters are tight, but these can be improved even further with information from external experiments. Here, we examine quantitatively the extent to which external priors can lead to improvement in projected constraints from a CMB-Stage IV (S4) experiment on neutrino and dark energy properties. We find that CMB S4 constraints on neutrino mass could be strongly enhanced by external constraints on the cold dark matter density ${\mathrm{\Omega }}_c{h}^2$ and the Hubble constant $H_0$. If polarization on the largest scales ($\ell <50$) will not be measured, an external prior on the primordial amplitude $A_s$ or the optical depth $\tau$ will also be important. A CMB constraint on the number of relativistic degrees of freedom, $N_{\mathrm{eff}}$, will benefit from an external prior on the spectral index $n_s$ and the baryon energy density ${\mathrm{\Omega }}_b{h}^2$. Finally, an external prior on $H_0$ will help constrain the dark energy equation of state ($w$).

Nonlocal gravity has been shown to provide a phenomenologically viable infrared modification of general relativity. A natural question is whether the required nonlocality can emerge from perturbative quantum loop corrections due to light particles. We show that this is not the case. For the value of the mass scale of the nonlocal models required by cosmology, the perturbative form factors obtained from the loop corrections, in the present cosmological epoch, are in the regime where they are local. The mechanism behind the generation of the required nonlocality must be more complex, possibly related to strong infrared effects and nonperturbative mass generation for the conformal mode.

We investigate QCD at large $\mu /T$ by using $Z_3$-symmetric $SU(3)$ gauge theory, where $\mu$ is the quark-number chemical potential and $T$ is temperature. We impose the flavor-dependent twist boundary condition on quarks in QCD. This QCD-like theory has the twist angle $\theta$ as a parameter, and agrees with QCD when $\theta =0$ and becomes symmetric when $\theta =2\pi /3$. For both QCD and the $Z_3$-symmetric $SU(3)$ gauge theory, the phase diagram is drawn in $\mu$–$T$ plane with the Polyakov-loop extended Nambu–Jona-Lasinio model. In the $Z_3$-symmetric $SU(3)$ gauge theory, the Polyakov loop $\phi$ is zero in the confined phase appearing at $T\lesssim 200\mathrm{MeV}$ and $\mu \lesssim 300\mathrm{MeV}$. The perfectly confined phase never coexists with the color superconducting (CSC) phase, since finite diquark condensate in the CSC phase breaks $Z_3$ symmetry and then makes $\phi$ finite. When $\mu \gtrsim 300\mathrm{MeV}$, the CSC phase is more stable than the perfectly confined phase at $T\lesssim 100\mathrm{MeV}$. Meanwhile, the chiral symmetry can be broken in the perfectly confined phase, since the chiral condensate is $Z_3$ invariant. Consequently, the perfectly confined phase is divided into the perfectly confined phase without chiral symmetry restoration in a region of $\mu \lesssim 300\mathrm{MeV}$ and $T\lesssim 200\mathrm{MeV}$ and the perfectly confined phase with chiral symmetry restoration in a region of $\mu \gtrsim 300\mathrm{MeV}$ and $100\lesssim T\lesssim 200\mathrm{MeV}$. At low temperature, the basic phase structure of $Z_3$-symmetric QCD-like theory remains in QCD. Properties of the sign problem in $Z_3$-symmetric theory are also discussed. We discuss a numerical framework to evaluate observables at $\theta =0$ from those at $\theta =2\pi /3$.

We derive a phenomenological no-lose theorem for naturalness up to the TeV scale, which applies when quantum corrections to the Higgs mass from top quarks are canceled by perturbative beyond Standard Model (BSM) particles (top partners) of similar multiplicity due to to some symmetry. Null results from LHC searches already seem to disfavor such partners if they are colored. Any partners with SM charges and $\sim \mathrm{TeV}$ masses will be exhaustively probed by the LHC and a future 100 TeV collider. Therefore, we focus on neutral top partners. While these arise in twin Higgs theories, we analyze neutral top partners as model-independently as possible using effective field theory and simplified model methods. We classify all perturbative neutral top partner structures in order to compute their irreducible low-energy signatures at proposed future lepton and hadron colliders, as well as the irreducible tunings suffered in each scenario. Central to our theorem is the assumption that SM-charged BSM states appear in the UV completion of neutral naturalness, which is the case in all known examples. Direct production at the 100 TeV collider then allows this scale to be probed at the $\sim 10\mathrm{TeV}$ level. We find that proposed future colliders probe any such scenario of naturalness with tuning of 10% or better. This provides very strong model-independent motivation for both new lepton and hadron colliders, which in tandem act as discovery machines for general naturalness. We put our results in context by discussing other possibilities for naturalness, including “swarms” of top partners, inherently nonperturbative or exotic physics, or theories without SM-charged states in the UV completion. Realizing a concrete scenario which avoids our arguments while still lacking experimental signatures remains an open model-building challenge.

We discuss a possible explanation of the recently observed diphoton excess at around 750 GeV as seen by the ATLAS and CMS experiments at the Large Hadron Collider. We calculate the cross section of the diphoton signature in two-Higgs-doublet models with the addition of a real isospin scalar multiplet without a vacuum expectation value, where a neutral component of such a representation can be a dark matter candidate. We find that the branching fraction of an additional $CP$-even Higgs boson $H$ from the doublet fields into the diphoton mode can be significantly enhanced, by up to a factor of ${10}^3$, with respect to the case of the simple two-Higgs-doublet model. Such a sizable enhancement is realized due to multicharged inert particle loops entering the $H\to \gamma \gamma$ decay mode. Through this enhancement, we obtain a suitable cross section of the $gg\to H\to \gamma \gamma$ process to explain the data with the fixed mass of $H$ being 750 GeV.

Motivated by the recent diphoton excess by both ATLAS and CMS collaborations at the LHC, we systematically investigate the production and diphoton decay of onia formed by pair of all possible color exotic scalars in minimal extension. When such scalar massive metastable colored and charged (MMCC) particles are produced in pair near threshold, $\eta$ onium can be formed and decay into diphoton through annihilation as $pp\to \eta \to \gamma \gamma$. Squarkonium is formed by metastable squarks in supersymmetric models such as stoponium. Diquarkonium is formed by metastable color sextet diquarks which may be realized in the Pati-Salam model. Octetonium is formed by color octet scalars bosons as in the Manohar-Wise model. Stoponium prediction is much smaller than the required signal to account for the diphoton excess. Due to the enhancement factor from color and electric charge, predictions of diquarkonium and octetonium are of $\mathcal{O}(10\mathrm{fb})$ which are significantly greater than the stoponium prediction. Since the color enhancement also results in large production at the colliders, such light color exotic states of $\mathcal{O}(375\mathrm{GeV})$ suffer from severe direct search constraints. On the other hand, if their dominant decay mode involve top quark, they may be buried in the $t\overline{t}$ plus jets samples and can potentially be searched via $t+j$ resonance.

The nonobservation of new particles at the LHC suggests the existence of a mass gap above the electroweak scale. This situation is adequately described through a general electroweak effective theory with the established fields and Standard Model symmetries. Its couplings contain all information about the unknown short-distance dynamics which is accessible at low energies. We consider a generic strongly coupled scenario of electroweak symmetry breaking, with heavy states above the gap, and analyze the imprints that its lightest bosonic excitations leave on the effective Lagrangian couplings. Different quantum numbers of the heavy states imply different patterns of low-energy couplings, with characteristic correlations which could be identified in future data samples. The predictions can be sharpened with mild assumptions about the ultraviolet behaviour of the underlying fundamental theory.

We use the Higgs coupling and the muon anomalous magnetic moment measurements to constrain the parameter space of the natural supersymmetry in the generalized minimal supergravity (GmSUGRA) model. We scan the parameter space of the GmSUGRA model with small electroweak fine-tuning measure (${\mathrm{\Delta }}_{\mathrm{EW}}\le 100$). The parameter space after applying various sparticle mass bounds; Higgs mass bounds; B-physics bounds; the muon magnetic moment constraint; and the Higgs coupling constraint from measurements at HL-LHC, ILC, and CEPC is shown in the planes of various interesting model parameters and sparticle masses. Our study indicates that the Higgs coupling and muon anomalous magnetic moment measurements can constrain the parameter space effectively. It is shown that ${\mathrm{\Delta }}_{\mathrm{EW}}\sim 30$, consistent with all constraints, and having supersymmetric contributions to the muon anomalous magnetic moment within $1\sigma$ can be achieved. The precision of $k_b$ and $k_{\tau }$ measurements at CEPC can bound $m_A$ to be above 1.2 TeV and 1.1 TeV respectively. The combination of the Higgs coupling measurement and muon anomalous magnetic moment measurement constrain the ${\tilde{e}}_R$ mass to be in the range from 0.6 TeV to 2 TeV. The range of both ${\tilde{e}}_L$ and ${\tilde{\nu }}_e$ masses is 0.4 TeV–1.2 TeV. In all cases, the ${\tilde{\chi }}_1^0$ mass needs to be small (mostly $\le 400\mathrm{GeV}$). The comparison of bounds in the $\tan \beta -m_A$ plane shows that the Higgs coupling measurement is complementary to the direct collider searches for heavy Higgs when constraining the natural SUSY. A few mass spectra in the typical region of parameter space after applying all constraints are shown as well.

We present the first detailed computation of the conversion of a bound muon into an electron mediated by a doubly charged $SU(2)$ singlet scalar. Although such particles are not too exotic, up to now their contribution to $\mu \text{−}e$ conversion is unknown. We close this gap by presenting a detailed calculation, which will allow the reader not only to fully comprehend the discussion but also to generalize our results to similar cases if needed. We furthermore compare the predictions, for both the general case and an example model featuring a neutrino mass at two-loop level, to current experimental data and future sensitivities. We show that, depending on the explicit values of the couplings as well as on the actual future limits on the branching ratio, $\mu \text{−}e$ conversion may potentially yield a lower limit on the doubly charged singlet scalar mass, which is stronger than what could be obtained by colliders. Our results considerably strengthen the case for low-energy lepton flavor violation searches being a very valuable addition to collider experiments.

We calculate the zeros of angular observables $P_4^{\prime }$ and $P_5^{\prime }$ of the angular distribution of 4-body decay $B\to K^{*}(\to K\pi )l^{+}{l}^{-}$ where LHCb, in its analysis of form-factor independent angular observables, has found deviations from the standard model predictions. In the large recoil region, we obtain relations between the zeros of $P_4^{\prime }$, $P_5^{\prime }$ and the zero (${\widehat{s}}_0$) of forward-backward asymmetry of lepton pair, $A_{FB}$. These relations are independent of hadronic uncertainties and depend only on the Wilson coefficients. We also construct a new observable, ${\mathcal{O}}_T^{L,R}$, whose zero in the standard model coincides with ${\widehat{s}}_0$, but in the presence of new physics contributions will show different behavior. Moreover, the profile of the new observable, even within the standard model, is very different from $A_{FB}$. We point out that precise measurements of these zeros in the near future would provide a crucial test of the standard model and would be useful in distinguishing between different possible new physics contributions to the Wilson coefficients.

The pion-photon transition form factor is studied by employing two types of sum rules: light cone sum rules (LCSR) and anomaly sum rules (ASR). By comparing the predictions for the pion-photon transition form factor, obtained from these two approaches, the applicability limit of the LCSRs at low momenta is determined. Reciprocally, the ASR threshold dependence on the momentum was extracted using our LCSR-based method in combination with two different types of pion distribution amplitudes and found that at higher $Q^2$ it approaches a constant.

We interpret the newly discovered pentaquark $P_c(4450)$ as a bound state of charmonium $\psi (2S)$ and the nucleon. The binding potential is due to the charmonium-nucleon interaction that in the heavy quark approximation is proportional to the product of the charmonium chromoelectric polarizability and the nucleon energy-momentum distribution. We use the large $N_c$ expansion to estimate the quarkonium polarizability and calculate the nucleon properties in the framework of the mean-field picture of light baryons. Two almost degenerate states $J^P=(1/2{)}^{-}$ and $J^P=(3/2{)}^{-}$ are predicted at the position of the $P_c(4450)$ pentaquark. We find that the nucleon-$\psi (2S)$ bound state has a naturally narrow width in the range of tens of MeV. The unitary multiplet partners of the $P_c(4450)$ pentaquark and the generalization to $b\overline{b}$-nucleon pentaquark bound states are discussed.

We obtain a prediction for the hadron-collider event-shape variable transverse thrust in which the terms enhanced in the dijet limit are resummed to next-to-next-to-leading logarithmic accuracy. Our method exploits universality properties made manifest in the factorized expression for the cross section and only requires one-loop calculations. The necessary two-loop ingredients are extracted using known results and existing numerical codes. Our technique is general and applicable to other observables as well.

We calculate the inclusive gluon correlation function for arbitrary number of gluons with full rapidity and transverse momentum dependence for the initial glasma state of the p-p, p-A, and A-A collisions. The formula we derive via superdiagrams generates cumulants for any number of gluons. Higher order cumulants contain information on correlations between multiple gluons, and they are necessary for calculations of higher dimensional ridges as well as flow coefficients from multiparticle correlations.

In this article we investigate the prospects for probing the strength of the possible nonstandard neutrino interactions (NSI) in long baseline neutrino oscillation experiments. We find that these experiments are sensitive to NSI couplings down to the level of 0.01–0.1 depending on the oscillation channel and the baseline length, as well as on the detector’s fiducial mass. We also investigate the interference of the leptonic $CP$ angle ${\delta }_{CP}$ with the constraining of the NSI couplings. It is found that the interference is strong in the case of the ${\nu }_e\leftrightarrow {\nu }_{\mu }$ and ${\nu }_e\leftrightarrow {\nu }_{\tau }$ transitions but not significant in other transitions. In our numerical analysis we apply the GLoBES software and use the LBNO setup as our benchmark.

We discuss the computation of the Higgs boson decay amplitude to two photons through the $W$-loop using dispersion relations. The imaginary part of the form factor $F_W(s)$ that parametrizes this decay is unambiguous in four dimensions. When it is used to calculate the unsubtracted dispersion integral, the finite result for the form factor $F_W(s)$ is obtained. However, the $F_W(s)$ obtained in this way differs by a constant term from the result of a diagrammatic computation, based on dimensional regularization. It is easy to accommodate the missing constant by writing a once-subtracted dispersion relation for $F_W(s)$ but it is unclear why the subtraction needs to be done. The goal of this paper is to investigate this question in detail. We show that the correct constant can be recovered within a dispersive approach in a number of ways that, however, either require an introduction of an ultraviolet regulator or unphysical degrees of freedom; unregulated and unsubtracted computations in the unitary gauge are insufficient, in spite of the fact that such computations give a finite result.

We study the lepton forward-backward asymmetry ${\mathcal{A}}_{FB}$ and the longitudinal $K^{*}$ polarization $F_L$, as well as an observable $P_2$ derived from them, in the rare decays $B\to K^{*}{\ell }^{+}{\ell }^{-}$, where ${\ell }^{+}{\ell }^{-}$ is either $e^{+}{e}^{-}$ or ${\mu }^{+}{\mu }^{-}$, using the full sample of 471 million $B\overline{B}$ events collected at the $\mathrm{\Upsilon }(4S)$ resonance with the BABAR, detector at the PEP-II $e^{+}{e}^{-}$ collider. We separately fit and report results for the $K^{*0}(892){\ell }^{+}{\ell }^{-}$ and $K^{*+}(892){\ell }^{+}{\ell }^{-}$ final states, as well as their combination $K^{*}{\ell }^{+}{\ell }^{-}$, in five disjoint dilepton mass-squared bins. An angular analysis of $B^{+}\to K^{*+}{\ell }^{+}{\ell }^{-}$ decays is presented here for the first time.

New data are reported from the operation of the PICO-60 dark matter detector, a bubble chamber filled with 36.8 kg of ${\mathrm{CF}}_3\mathrm{I}$ and located in the SNOLAB underground laboratory. PICO-60 is the largest bubble chamber to search for dark matter to date. With an analyzed exposure of 92.8 livedays, PICO-60 exhibits the same excellent background rejection observed in smaller bubble chambers. Alpha decays in PICO-60 exhibit frequency-dependent acoustic calorimetry, similar but not identical to that reported recently in a ${\mathrm{C}}_3{\mathrm{F}}_8$ bubble chamber. PICO-60 also observes a large population of unknown background events, exhibiting acoustic, spatial, and timing behaviors inconsistent with those expected from a dark matter signal. These behaviors allow for analysis cuts to remove all background events while retaining 48.2% of the exposure. Stringent limits on weakly interacting massive particles interacting via spin-dependent proton and spin-independent processes are set, and most interpretations of the DAMA/LIBRA modulation signal as dark matter interacting with iodine nuclei are ruled out.

Heavy quarkonia in a homogeneous magnetic field are analyzed by using a potential model with constituent quarks. To obtain anisotropic wave functions and corresponding eigenvalues, the cylindrical Gaussian expansion method is applied, where the anisotropic wave functions are expanded by a Gaussian basis in the cylindrical coordinates. Deformation of the wave functions and the mass shifts of the S-wave heavy quarkonia (${\eta }_c$, $J/\psi$, ${\eta }_c(2S)$, $\psi (2S)$ and bottomonia) are examined for the wide range of external magnetic field. The spatial structure of the wave functions changes drastically as adjacent energy levels cross each other. Possible observables in heavy-ion collision experiments and future lattice QCD simulations are also discussed.

Hydrodynamics can be formulated as the gradient expansion of conserved currents in terms of the fundamental fields describing the near-equilibrium fluid flow. In the relativistic case, the Navier-Stokes equations follow from the conservation of the stress-energy tensor to first order in derivatives. In this paper, we go beyond the presently understood second-order hydrodynamics and discuss the systematization of obtaining the hydrodynamic expansion to an arbitrarily high order. As an example of the algorithm that we present, we fully classify the gradient expansion at third order for neutral fluids in four dimensions, thus finding the most general next-to-leading-order corrections to the relativistic Navier-Stokes equations in curved space-time. In doing so, we list 20 new transport coefficient candidates in the conformal case and 68 in the nonconformal case. As we do not consider any constraints that could potentially arise from the local entropy current analysis, this is the maximal possible set of neutral third-order transport coefficients. To investigate the physical implications of these new transport coefficients, we obtain the third-order corrections to the linear dispersion relations that describe the propagation of diffusion and sound waves in relativistic fluids. We also compute the corrections to the scalar (spin-2) two-point correlation function of the third-order stress-energy tensor. Furthermore, as an example of a nonlinear hydrodynamic flow, we calculate the third-order corrections to the energy density of a boost-invariant Bjorken flow. Finally, we apply our field theoretic results to the $\mathcal{N}=4$ supersymmetric Yang-Mills fluid at infinite ’t Hooft coupling and an infinite number of colors to find the values of five new linear combinations of the conformal transport coefficients.