We study the violation of Bell-Mermin-Klyshko (BMK) inequalities in initial quantum states of scalar fields in inflation. We show that the Bell inequality is maximally violated by the Bunch-Davies vacuum which is a two-mode squeezed state of a scalar field. However, we find that the violation of the BMK inequalities does not increase with the number of modes to measure. We then consider a non-Bunch-Davies vacuum expressed by a four-mode squeezed state of two scalar fields. Remarkably, we find that the violation of the BMK inequalities increases exponentially with the number of modes to measure. This shows that the BMK inequalities are useful to classify the initial quantum state of the Universe.

Recently, the LIGO observatory reported the first direct observation of gravitational waves, with a signal consistent with a binary black hole merger. This detection triggered several follow-up searches for coincident emission in electromagnetic waves as well as neutrinos, but no such emission was found. In this article, the implications of the nondetection of counterpart neutrinos are investigated using general arguments. The results are interpreted with a parameter denoting the energy emitted in neutrinos relative to the energy emitted in gravitational waves. The bound on this parameter from the diffuse astrophysical neutrino flux detected by the IceCube Neutrino Observatory is discussed. It is found that, currently, the nondetection of counterpart neutrinos puts a bound comparable to the one from the diffuse astrophysical neutrino flux. This bound is then used to constrain the amount of matter in the black hole binary environment. Finally, the sensitivity to this parameter in future gravitational wave observation runs is investigated. It is shown how the detection of one or more neutrinos from a single merger would strongly constrain the source population and evolution.

The origin of the isotropic gamma-ray background (IGRB)—the portion of the extragalactic gamma-ray sky that is not resolvable into individual point sources—provides a powerful probe into the evolution of the high-energy Universe. Star-forming galaxies (SFGs) are among the most likely contributors to the IGRB, though their contribution is difficult to constrain because their flux distribution is dominated by numerous faint sources. We produce a novel joint-likelihood analysis of the $\gamma$-ray emission from 584 SFGs, utilizing advanced statistical techniques to compare the distribution of low-significance excesses against the non-Poissonian $\gamma$-ray background fluctuations. We first examine the theoretically well-motivated relationship between the far-IR and $\gamma$-ray luminosities of SFGs, utilizing a model where the $\gamma$-ray luminosity is given by ${\log }_{10}({\mathrm{L}}_{\gamma }/(\mathrm{erg}{\mathrm{s}}^{-1}))=\alpha {\log }_{10}({\mathrm{L}}_{\mathrm{IR}}/(10{{}^{10}\mathrm{L}}_{\odot }))+\beta$. We calculate best-fit parameters $\alpha =1.18\pm 0.15$, $\beta =38.49\pm 0.24$, with a log-normal dispersion in this relationship given by $\sigma =0.39\pm 0.12$. The best-fit values of $\alpha$ and $\beta$ are consistent with previous studies. We find a larger dispersion in the far-IR to $\gamma$-ray correlation than previous studies. This dispersion is significant at the level of $5.7\sigma$. These results imply that SFGs significantly contribute to the IGRB, producing between ${61.0}_{-18.3}^{+30.2}\%$ of the total IGRB intensity above an energy of 1 GeV. Along with recent works, this strongly indicates that multiple source classes provide comparable contributions to the IGRB intensity. We discuss the implication of these results for the interpretation of the IceCube neutrinos.

A search for cosmic neutrino sources using the data collected with the ANTARES neutrino telescope between early 2007 and the end of 2015 is performed. For the first time, all neutrino interactions—charged- and neutral-current interactions of all flavors—are considered in a search for point-like sources with the ANTARES detector. In previous analyses, only muon neutrino charged-current interactions were used. This is achieved by using a novel reconstruction algorithm for shower-like events in addition to the standard muon track reconstruction. The shower channel contributes about 23% of all signal events for an $E^{-2}$ energy spectrum. No significant excess over background is found. The most signal-like cluster of events is located at $(\alpha ,\delta )=(343.8°,23.5°)$ with a significance of $1.9\sigma$. The neutrino flux sensitivity of the search is about $E^{2}d\mathrm{\Phi }/dE=6\times {10}^{-9}\mathrm{GeV}{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$ for declinations from $-90°$ up to $-42°$, and below ${10}^{-8}\mathrm{GeV}{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$ for declinations up to 5°. The directions of 106 source candidates and 13 muon track events from the IceCube high-energy sample events are investigated for a possible neutrino signal and upper limits on the signal flux are determined.

We discuss phenomenological criteria for defining “axion windows,” namely regions in the parameter space of the axion-photon coupling where realistic models live. Currently, the boundaries of this region depend on somewhat arbitrary criteria, and it would be highly desirable to specify them in terms of precise phenomenological requirements. We first focus on hadronic axion models within post-inflationary scenarios, in which the initial abundance of the new vectorlike quarks $Q$ is thermal. We classify their representations $R_Q$ by requiring that (i) the $Q$ are sufficiently short lived to avoid issues with long-lived strongly interacting relics, (ii) the theory remains weakly coupled up to the Planck scale. The more general case of multiple $R_Q$ is also studied, and the absolute upper and lower bounds on the axion-photon coupling as a function of the axion mass is identified. Pre-inflationary scenarios in which the axion decay constant remains bounded as $f_a\le 5\times {10}^{11}\mathrm{GeV}$ allow for axion-photon couplings only about 20% larger. Realistic Dine-Fischler-Srednicki-Zhitnitsky type of axion models also remain encompassed within the hadronic axion window. Some mechanisms that can allow to enhance the axion-photon coupling to values sizeably above the preferred window are discussed.

Dark matter (DM) is added to the Froggatt-Nielsen (FN) mechanism, and conditions for its successful freeze-out identified. Requesting the FN scale ${\mathrm{\Lambda }}_{\mathrm{FN}}$ to be the cutoff of the theory renders freeze-out scenarios surprisingly few. Fermionic DM is typically charged under $U(1{)}_{\mathrm{FN}}$, with the dominant annihilation channel a $CP$-even flavon $+$ $CP$-odd flavon. A minimal case is when the DM-flavon coupling strength is $\mathcal{O}(1)$, with several implications: (1) the DM mass is $\mathcal{O}(100\mathrm{GeV}–1\mathrm{TeV})$, thanks to the WIMP coincidence, (2) requiring perturbativity of couplings puts a lower and upper limit on the flavor scale, $2\mathrm{TeV}\lesssim {\mathrm{\Lambda }}_{\mathrm{FN}}\lesssim 14\mathrm{TeV}$, on account of its relation to DM mass and couplings, (3) DM is a “secluded WIMP” effectively hidden from collider and direct detection searches. Limits on the masses of dark matter and mediators from kaon mixing measurements constitute the best constraints, surpassing Xenon1T, Fermi-LAT, and the LHC. Future direct detection searches, and collider searches for missing energy plus a single jet/bottom/top, are promising avenues for discovery.

We investigate a model with local ${\mathrm{U}(1)}_{B-L}$ and discrete $Z_2$ symmetries where two types of weak isospin singlet neutrinos, vectorlike charged leptons, and exotic scalar fields are introduced. The linear seesaw mechanism is induced at the one-loop level through Yukawa interactions associated with the standard model leptons and exotic fields. We also discuss lepton flavor violation and a muon anomalous dipole magnetic moment induced by the new Yukawa interaction. In addition, our model has dark matter candidate which is the lightest $Z_2$ odd neutral particle. We calculate the relic density and constraints from direct detection.

The parton distribution functions (PDFs) with QED corrections are obtained by solving the $\mathrm{QCD}\otimes \mathrm{QED}$ DGLAP evolution equations in the framework of the “valon” model at the next-to-leading-order QCD and the leading-order QED approximations. Our results for the PDFs with QED corrections in this phenomenological model are in good agreement with the newly related CT14QED global fits code [Phys. Rev. D 93, 114015 (2016)] and APFEL (NNPDF2.3QED) program [Comput. Phys. Commun. 185, 1647 (2014)] in a wide range of $x=[{10}^{-5},1]$ and $Q^2=[0.283,{10}^8]{\mathrm{GeV}}^2$. The model calculations agree rather well with those codes. In the latter, we proposed a new method for studying the symmetry breaking of the sea quark distribution functions inside the proton.

We study the impact of anomalous gauge boson and fermion couplings on the production of $W^{+}{W}^{-}$ pairs at the LHC. Helicity amplitudes are presented separately to demonstrate the sources of new physics contributions and the impact of QCD and electroweak corrections. The QCD corrections have important effects on the fits to anomalous couplings, in particular when one $W$ boson is longitudinally polarized and the other is transversely polarized. In effective field theory language, we demonstrate that the dimension-6 approximation to constraining new physics effects in $W^{+}{W}^{-}$ pair production fails at $p_T\sim 500–1000\mathrm{GeV}$.

The $H\to \tau \tau$ decays form a promising channel for tests of the $CP$ invariance of Higgs boson couplings. A previous study has shown the viability of deep learning techniques for such a measurement. In this paper, the study is extended to consider potential sources of uncertainty. Effects due to the limited experimental resolution are discussed. Furthermore, systematics due to $\tau$ decay modeling for complex cascade decays to ${\tau }^{\pm }\to a_1^{\pm }{\nu }_{\tau }\to {\rho }^0{\pi }^{\pm }{\nu }_{\tau }\to 3{\pi }^{\pm }{\nu }_{\tau }$ are also addressed. Various parametrizations using low-energy collision data are considered.

In the context of scalar quantum field theory, we introduce a class of generically nonlinear quantum-background splits for which the splitting Ward identity, encoding the single-field dependence in the effective action, can be solved exactly. We show that this can be used to construct an effective action which is both covariant and dependent on the background and fluctuation fields only through a single total field in a way independent from the dynamics. Moreover, we discuss the criteria under which the ultraviolet symmetries are inherited by the quantum effective action. The approach is demonstrated through some examples, including the $O(N)$ effective field theory, which might be of interest for the Higgs sector of the Standard Model or its extensions.

We study the Blume-Capel universality class in $d=\frac{10}{3}-\epsilon$ dimensions. The renormalization group flow is extracted by looking at poles in fractional dimension of three loop diagrams using $\overline{\mathrm{MS}}$. The theory is the only nontrivial universality class which admits an expansion to three dimensions with $\epsilon =\frac{1}{3}<1$. We compute the relevant scaling exponents and estimate some of the operator product expansion coefficients to the leading order. Our findings agree with and complement conformal field theory results. Finally we discuss a family of nonunitary multicritical models which includes the Lee-Yang and Blume-Capel classes as special cases.

Deviations from the standard model prediction have been observed not only in $b\to c$ charged current interactions but also in $b\to s$ flavor changing neutral current interactions. In particular, the deviation observed in the measured ratio of branching fractions $R_D=\mathcal{B}(B\to D\tau \nu )/\mathcal{B}(B\to Dl\nu )$ and $R_{D^{*}}=\mathcal{B}(B\to D^{*}\tau \nu )/\mathcal{B}(B\to D^{*}l\nu )$, where $l=(e,\mu )$, is more pronounced and the combined excess currently stands at a $3.9\sigma$ level. If it persists and is confirmed by future experiments, it would be a definite hint of new physics. In this context, we consider $B_c\to {\eta }_{c}l\nu$ and $B_c\to J/\mathrm{\Psi }l\nu$ decays mediated via $b\to cl\nu$ charged current interactions and employ an effective theory approach to give a prediction on various observables such as the ratio of the branching ratio, tau polarization fraction, and forward-backward asymmetry for these decay modes.

We compare correlators for pseudoscalar and vector mesons made from valence strange quarks using the clover quark and highly improved staggered quark (HISQ) formalisms in full lattice QCD. We use fully nonperturbative methods to normalize vector and axial vector current operators made from HISQ quarks, clover quarks and from combining HISQ and clover fields. This allows us to test expectations for the renormalization factors based on perturbative QCD, with implications for the error budget of lattice QCD calculations of the matrix elements of clover-staggered $b$-light weak currents, as well as further HISQ calculations of the hadronic vacuum polarization. We also compare the approach to the (same) continuum limit in clover and HISQ formalisms for the mass and decay constant of the $\varphi$ meson. Our final results for these parameters, using single-meson correlators and allowing an uncertainty for the neglect of quark-line disconnected diagrams are: $M_{\varphi }=1.023(6)\mathrm{GeV}$ and $f_{\varphi }=0.238(3)\mathrm{GeV}$ in good agreement with experiment. The results come from calculations in the HISQ formalism using gluon fields that include the effect of $u$, $d$, $s$ and $c$ quarks in the sea with three lattice spacing values and $m_{u/d}$ values going down to the physical point.

We perform a high statistics study of the $J^P=0^{+}$ and $1^{+}$ charmed-strange mesons, $D_{s0}^{*}(2317)$ and $D_{s1}(2460)$, respectively. The effects of the nearby $DK$ and $D^{*}K$ thresholds are taken into account by employing the corresponding four-quark operators. Six ensembles with $N_f=2$ nonperturbatively $\mathcal{O}(a)$ improved clover Wilson sea quarks at $a=0.07\mathrm{fm}$ are employed, covering different spatial volumes and pion masses: linear lattice extents $L/a=24$, 32, 40, 64, equivalent to 1.7 fm to 4.5 fm, are realized for $m_{\pi }=290\mathrm{MeV}$ and $L/a=48$, 64 or 3.4 fm and 4.5 fm for an almost physical pion mass of 150 MeV. Through a phase shift analysis and the effective range approximation we determine the scattering lengths, couplings to the thresholds and the infinite-volume masses. Differences relative to the experimental values are observed for these masses, however, this is likely to be due to discretization effects as spin-averaged quantities and splittings are reasonably compatible with experiment. We also compute the weak decay constants of the scalar and axialvector and find $f_V^{0^{+}}=114(2)(0)(+5)(10)\mathrm{MeV}$ and $f_A^{1^{+}}=194(3)(4)(+5)(10)\mathrm{MeV}$, where the errors are due to statistics, renormalization, finite-volume and lattice spacing effects.

We perform a global Bayesian analysis of currently available neutrino data, putting data from oscillation experiments, neutrinoless double beta decay ($0\nu \beta \beta$), and precision cosmology on an equal footing. We evaluate the discovery potential of future $0\nu \beta \beta$ experiments and the Bayes factor of the two possible neutrino mass ordering schemes for different prior choices. We show that the indication for normal ordering is still very mild and does not strongly depend on realistic prior assumptions or different combinations of cosmological data sets. We find a wide range for $0\nu \beta \beta$ discovery potential, depending on the absolute neutrino mass scale, mass ordering and achievable background level.

We report a Dalitz plot analysis of charmless hadronic decays of charged $B$ mesons to the final state $K_S^0{\pi }^{+}{\pi }^0$ using the full BABAR data set of $470.9\pm 2.8\mathrm{million}$ $B\overline{B}$ events collected at the $\mathrm{{\rm Y}}(4S)$ resonance. We measure the overall branching fraction and $CP$ asymmetry to be $\mathcal{B}(B^{+}\to K^0{\pi }^{+}{\pi }^0)=(31.8\pm 1.8\pm 2.1_{-0.0}^{+6.0})\times {10}^{-6}$ and $A_{CP}(B^{+}\to K^0{\pi }^{+}{\pi }^0)=0.07\pm 0.05\pm 0.03_{-0.03}^{+0.02}$, where the uncertainties are statistical, systematic, and due to the signal model, respectively. This is the first measurement of the branching fraction for $B^{+}\to K^0{\pi }^{+}{\pi }^0$. We find first evidence of a $CP$ asymmetry in $B^{+}\to K^{*}(892{)}^{+}{\pi }^0$ decays: $A_{CP}(B^{+}\to K^{*}(892{)}^{+}{\pi }^0)=-0.52\pm 0.14\pm 0.04_{-0.02}^{+0.04}$. The significance of this asymmetry, including systematic and model uncertainties, is 3.4 standard deviations. We also measure the branching fractions and $CP$ asymmetries for three other intermediate decay modes.

Anti-Hermitian mass terms are considered, in addition to Hermitian ones, for $\mathcal{P}\mathcal{T}$-symmetric complex-scalar and fermionic field theories. In both cases, the Lagrangian can be written in a manifestly symmetric form in terms of the $\mathcal{P}\mathcal{T}$-conjugate variables, allowing for an unambiguous definition of the equations of motion. After discussing the resulting constraints on the consistency of the variational procedure, we show that the invariance of a non-Hermitian Lagrangian under a continuous symmetry transformation does not imply the existence of a corresponding conserved current. Conserved currents exist, but these are associated with transformations under which the Lagrangian is not invariant and which reflect the well-known interpretation of $\mathcal{P}\mathcal{T}$-symmetric theories in terms of systems with gain and loss. A formal understanding of this unusual feature of non-Hermitian theories requires a careful treatment of Noether’s theorem, and we give specific examples for illustration.