The neutrino mixing parameters are thoroughly studied using renormalization-group evolution of Dirac neutrinos with recently proposed parametrization of the neutrino mixing angles referred to as “high-scale mixing relations.” The correlations among all neutrino mixing and $CP$ violating observables are investigated. The predictions for the neutrino mixing angle ${\theta }_{23}$ are precise, and could be easily tested by ongoing and future experiments. We observe that the high-scale mixing unification hypothesis is incompatible with Dirac neutrinos due to updated experimental data.

We present a new method to analyze upcoming results in the search for $CP$ violating neutrino oscillations. The $CP$ violating amplitudes ${\mathcal{A}}_{\alpha \beta }^{kj}$ provide parametrization independent observables, which will be accessible by experiments soon. The strong prediction of a unique ${\mathcal{A}}_{\alpha \beta }^{kj}$ (the Jarlskog invariant) in case of the standard three neutrino model does not hold in models with new physics beyond the standard model. Nevertheless there are still correlations among the amplitudes depending on the specific model. Due to these correlations it is possible to reject specific new physics models by determining only 3 of the $CP$ violating amplitudes.

An extended Higgs sector may allow for new scalar particles well below the weak scale. In this work, we present a detailed study of a light scalar $S$ with enhanced coupling to leptons, which could be responsible for the existing discrepancy between experimental and theoretical determinations of the muon anomalous magnetic moment. We present an ultraviolet completion of this model in terms of the lepton-specific two-Higgs-doublet model and an additional scalar singlet. We then analyze a plethora of experimental constraints on the universal low energy model, and this UV completion, along with the sensitivity reach at future experiments. The most relevant constraints originate from muon and kaon decays, electron beam dump experiments, electroweak precision observables, rare $B_d$ and $B_s$ decays and Higgs branching fractions. The properties of the leptonic Higgs portal imply an enhanced coupling to heavy leptons, and we identify the most promising search mode for the high-luminosity electron-positron colliders as $e^{+}+e^{-}\to {\tau }^{+}+{\tau }^{-}+S\to {\tau }^{+}+{\tau }^{-}+\ell +\overline{\ell }$, where $\ell =e$, $\mu$. Future analyses of existing data from BABAR and Belle, and from the upcoming Belle II experiment, will enable tests of this model as a putative solution to the muon $g-2$ problem for $m_S<3.5\mathrm{GeV}$.

The jet trimming procedure has been demonstrated to greatly improve event reconstruction in hadron collisions by mitigating contamination due initial state radiation, multiple interactions, and event pileup. Meanwhile, Qjets—a nondeterministic approach to tree-based jet substructure—has been shown to be a powerful technique in decreasing random statistical fluctuations, yielding significant effective luminosity improvements. This manifests through an improvement in the significance $S/\delta B$, relative to conventional methods. Qjets also provides novel observables in many cases, like mass-volatility, that could be used to further discriminate between signal and background events. The statistical robustness and volatility observables, for tagging, are obtained simultaneously. We explore here a combination of the two techniques, and demonstrate that significant enhancements in discovery potentials may be obtained in nontrivial ways. We will illustrate this by considering a diboson resonance analysis as a case study, enabling us to interpolate between scenarios where the gains are purely due to statistical robustness and scenarios where the gains are also reinforced by volatility variable discriminants. The former, for instance, is applicable to digluon/diquark resonances, while the latter will be of relevance to $\mathrm{di}\text{−}{W}^{\pm }/\mathrm{di}\text{−}{Z}^0$ resonances, where the boosted vector bosons are decaying hadronically and have an intrinsic mass scale attached to them. We argue that one can enhance signal significance and discovery potentials markedly through stochastic grooming, and help augment studies at the Large Hadron Collider and future hadron colliders.

We study single spin asymmetries at one-loop accuracy in Drell-Yan processes in which one of the initial hadrons is transversely polarized. The spin-dependent part of differential cross sections can be factorized with various hadronic matrix elements of twist-2 and twist-3 operators. These operators can be of even and odd chirality. In this work, the studied observables of asymmetries are differential cross sections with different weights. These weights are selected so that the observables are spin dependent and their virtual corrections are completely determined by the quark form factor. In the calculations of one-loop corrections we meet collinear divergences in the contributions involving chirality-odd and chirality-even operators. We find that all of the divergences can be correctly subtracted. Therefore, our results give an explicit example of QCD factorization at one loop with twist-3 operators, especially QCD factorization with chirality-odd twist-3 operators.

The hidden-charmed pentaquark $P_c(4450)$ and the charmonium-like state $Y(4274)$ are investigated as a ${\overline{D}}^{*}{\mathrm{\Sigma }}_c$ and a $D_s{\overline{D}}_{s0}(2317)$ molecular state, respectively. The spin parities of these two states cannot be well understood if only S-wave ${\overline{D}}^{*}{\mathrm{\Sigma }}_c$ and $D_s{\overline{D}}_{s0}(2317)$ interactions are considered. In this work, the interactions are studied in a quasipotential Bethe-Salpeter equation approach with a partial wave decomposition on spin parity $J^P$, and the contributions of different partial waves are studied in a two-channel scattering model including a generating channel and an observation channel. Two poles at $4447\pm 4i$ and $4392\pm 46i\mathrm{MeV}$ are produced from the ${\overline{D}}^{*}{\mathrm{\Sigma }}_c$ interaction coupled with the $J/\psi p$ channel in $3/2^{-}$ wave and $5/2^{+}$ wave, respectively. The peak for the $5/2^{+}$ state has a comparable height as that of the $3/2^{-}$ state in the $J/\psi p$ invariant mass spectrum. The $D_s{\overline{D}}_{s0}(2317)$ interaction coupled with the $J/\psi \varphi$ channel is studied and a pole at $4275\pm 11i\mathrm{MeV}$ is produced in $J^P=1^{+}$ wave, which corresponds to P-wave $D_s{\overline{D}}_{s0}(2317)$ interaction. The pole from S-wave $D_s{\overline{D}}_{s0}(2317)$ interaction is far below that from P-wave interaction even the $J/\psi \varphi$ threshold, so cannot be observed in the $J/\psi \varphi$ channel. The result suggests that in these cases a state carrying a spin parity corresponding to P-wave interaction should be taken as seriously as these carrying a spin parity corresponding to S-wave interaction in the hadronic molecular state picture.

Information geometry can be used to understand and optimize Higgs boson measurements at the LHC. The Fisher information encodes the maximum sensitivity of observables to model parameters for a given experiment. Applied to higher-dimensional operators, it defines the new physics reach of any LHC signature. We calculate the Fisher information for Higgs production in weak boson fusion with decays into tau pairs and four leptons and for Higgs production in association with a single top quark. In a next step, we analyze how the differential information is distributed over phase space, which defines optimal event selections. Conversely, we consider the information in the distribution of a subset of the kinematic variables, showing which production and decay observables are the most powerful and how much information is lost in traditional histogram-based analysis methods compared to fully multivariate ones.

The rare decay $B\to K^{*}(\to K\pi )\nu \overline{\nu }$ is expected to play an important role in searches for physics beyond the Standard Model at the near future $B$-physics experiments. We investigate resonant and nonresonant backgrounds that arise beyond the narrow-width approximation for the $K^{*}$. Nonresonant $B\to K\pi \nu \overline{\nu }$ decays are analyzed in the region of low hadronic recoil, where $B\to K\pi$ form factors from the heavy-hadron-chiral-perturbation theory are available. In a Breit-Wigner–type model interference-induced effects in the $K^{*}$ signal region are found to be sizable, as large as 20% in the branching ratio. Corresponding effects in the longitudinal polarization fraction $F_L$ are smaller, at most around a few percent. Effects of the broad scalar states $K_0^{*}$ and $\kappa$ are at the level of percent in the branching fraction in the $K^{*}$ signal region and negligible in $F_L$. Since the backgrounds to $F_L$ are small, this observable constitutes a useful probe of form factor calculations or, alternatively, of right-handed currents in the entire $q^2$ region. The forward-backward asymmetry in the $K\pi$ system, $A_{\mathrm{FB}\mathrm{L}}^K$, with normalization to the longitudinal decay rate probes predominantly $S$, $P$-wave interference free of short-distance coefficients and can therefore be used to control the resonant and nonresonant backgrounds.

Based on the full BABAR data sample of 466.5 million $B\overline{B}$ pairs, we present measurements of the electron spectrum from semileptonic $B$ meson decays. We fit the inclusive electron spectrum to distinguish Cabibbo-Kobayashi-Maskawa (CKM) suppressed $B\to X_{u}e\nu$ decays from the CKM-favored $B\to X_{c}e\nu$ decays, and from various other backgrounds, and determine the total semileptonic branching fraction $\mathcal{B}(B\to Xe\nu )=(10.34\pm {0.04}_{\mathrm{stat}}\pm 0.26_{\mathrm{syst}})\%$, averaged over $B^{\pm }$ and $B^0$ mesons. We determine the spectrum and branching fraction for charmless $B\to X_{u}e\nu$ decays and extract the CKM element $|V_{ub}|$, by relying on four different QCD calculations based on the heavy quark expansion. While experimentally, the electron momentum region above $2.1\mathrm{GeV}/c$ is favored, because the background is relatively low, the uncertainties for the theoretical predictions are largest in the region near the kinematic endpoint. Detailed studies to assess the impact of these four predictions on the measurements of the electron spectrum, the branching fraction, and the extraction of the CKM matrix element $|V_{ub}|$ are presented, with the lower limit on the electron momentum varied from $0.8\mathrm{GeV}/c$ to the kinematic endpoint. We determine $|V_{ub}|$ using each of these different calculations and find, $|V_{ub}|=(3.794\pm {0.107}_{\exp }{}_{-0.219\mathrm{SF}}^{+0.292}{}_{-0.068\text{theory}}^{+0.078})\times {10}^{-3}$ (De Fazio and Neubert), $(4.563\pm {0.126}_{\exp }{}_{-0.208\mathrm{SF}}^{+0.230}{}_{-0.163\text{theory}}^{+0.162})\times {10}^{-3}$ (Bosch, Lange, Neubert, and Paz), $(3.959\pm {0.104}_{\exp }{}_{-0.154\mathrm{SF}}^{+0.164}{}_{-0.079\text{theory}}^{+0.042})\times {10}^{-3}$ (Gambino, Giordano, Ossola, and Uraltsev), $(3.848\pm {0.108}_{\exp }{}_{-0.070\text{theory}}^{+0.084})\times {10}^{-3}$ (dressed gluon exponentiation), where the stated uncertainties refer to the experimental uncertainties of the partial branching fraction measurement, the shape function parameters, and the theoretical calculations.

We suggest that nonminimally coupled scalar fields can lead to modifications of the microphysics in the interiors of relativistic stars. As a concrete example, we consider the generation of a nonzero photon mass in such high-density environments. This is achieved by means of a light gravitational scalar, and the scalarization phase transition in scalar-tensor theories of gravitation. Two distinct models are presented, and phenomenological implications are briefly discussed.

We present a new test of gravitational physics by comparing the growth rate of cosmic structure measured around voids with that measured around galaxies in the same large-scale structure data set: the low-redshift 6-degree Field Galaxy Survey. By fitting a redshift space distortion model to the two-dimensional galaxy-galaxy and void-galaxy correlation functions, we recover the growth rate values $f{\sigma }_8=0.42\pm 0.06$ and $0.39\pm 0.11$, respectively. The environmental dependence of cosmological statistics can potentially discriminate between modified-gravity scenarios which modulate the growth rate as a function of scale or environment and test the underlying assumptions of homogeneity and isotropy.

We study the effects of acceleration on fermionic Gaussian states of localized modes of a Dirac field. We consider two wave packets in a Gaussian state and transform these to an accelerated frame of reference. In particular, we formulate the action of this transformation as a fermionic quantum channel. Having developed the general framework for fermions, we then investigate the entanglement of the vacuum, as well as the entanglement in Bell states. We find that with increasing acceleration vacuum entanglement increases, while the entanglement of Bell states decreases. Notably, our results have an immediate operational meaning given the localization of the modes.

A general field-theoretic framework for the treatment of liquid-gas phase transitions is developed. Starting from a fundamental four-dimensional field theory at nonzero temperature and density, an effective three-dimensional field theory is derived. The effective field theory has a sign problem at finite density. Although finite density explicitly breaks charge conjugation $\mathcal{C}$, there remains a symmetry under $\mathcal{C}\mathcal{K}$, where $\mathcal{K}$ is complex conjugation. We consider four models: relativistic fermions, nonrelativistic fermions, static fermions and classical particles. The interactions are via an attractive potential due to scalar field exchange and a repulsive potential due to massive vector exchange. The field-theoretic representation of the partition function is closely related to the equivalence of the sine-Gordon field theory with a classical gas. The thermodynamic behavior is extracted from $\mathcal{C}\mathcal{K}$-symmetric complex saddle points of the effective field theory at tree level. In the cases of nonrelativistic fermions and classical particles, we find complex saddle point solutions but no first-order transitions, and neither model has a ground state at tree level. The relativistic and static fermions show a liquid-gas transition at tree level in the effective field theory. The liquid-gas transition, when it occurs, manifests as a first-order line at low temperature and high density, terminated by a critical end point. The mass matrix controlling the behavior of correlation functions is obtained from fluctuations around the saddle points. Due to the $\mathcal{C}\mathcal{K}$ symmetry of the models, the eigenvalues of the mass matrix are not always real but can be complex. This leads to the existence of disorder lines, which mark the boundaries where the eigenvalues go from purely real to complex. The regions where the mass matrix eigenvalues are complex are associated with the critical line. In the case of static fermions, a powerful duality between particles and holes allows for the analytic determination of both the critical line and the disorder lines. Depending on the values of the parameters, either zero, one, or two disorder lines are found. Numerical results for relativistic fermions give a very similar picture.

We present the first self-consistent direct calculation of a spectral function in the framework of the functional renormalization group. The study is carried out in the relativistic $O(N)$ model, where the full momentum dependence of the propagators in the complex plane as well as momentum-dependent vertices are considered. The analysis is supplemented by a comparative study of the Euclidean momentum dependence and of the complex momentum dependence on the level of spectral functions. This work lays the groundwork for the computation of full spectral functions in more complex systems.

We study indirect detection signals from solar annihilation of dark matter (DM) particles into light right-handed (RH) neutrinos with a mass in a 1–5 GeV range. These RH neutrinos can have a sufficiently long lifetime to allow them to decay outside the Sun, and their delayed decays can result in a signal in gamma rays from the otherwise “dark” solar direction, and also a neutrino signal that is not suppressed by the interactions with solar medium. We find that the latest Fermi-LAT and IceCube results place limits on the gamma ray and neutrino signals, respectively. Combined photon and neutrino bounds can constrain the spin-independent DM-nucleon elastic scattering cross section better than direct detection experiments for DM masses from 200 GeV up to several TeV. The bounds on spin-dependent scattering are also much tighter than the strongest limits from direct detection experiments.

Dihadron and isolated direct photon-hadron angular correlations are measured in $p+p$ collisions at $\sqrt{s}=510\mathrm{GeV}$. Correlations of charged hadrons of $0.7<p_T<10\mathrm{GeV}/c$ with ${\pi }^0$ mesons of $4<p_T<15\mathrm{GeV}/c$ or isolated direct photons of $7<p_T<15\mathrm{GeV}/c$ are used to study nonperturbative effects generated by initial-state partonic transverse momentum and final-state transverse momentum from fragmentation. The nonperturbative behavior is characterized by measuring the out-of-plane transverse momentum component $p_{\mathrm{out}}$ perpendicular to the axis of the trigger particle, which is the high-$p_T$ direct photon or ${\pi }^0$. Nonperturbative evolution effects are extracted from Gaussian fits to the away-side inclusive-charged-hadron yields for different trigger-particle transverse momenta ($p_T^{\mathrm{trig}}$). The Gaussian widths and root mean square of $p_{\mathrm{out}}$ are reported as a function of the interaction hard scale $p_T^{\mathrm{trig}}$ to investigate possible transverse-momentum-dependent evolution differences between the ${\pi }^0\text{−}{\mathrm{h}}^{\pm }$ and direct photon-${\mathrm{h}}^{\pm }$ correlations and factorization breaking effects. The widths are found to decrease with $p_T^{\mathrm{trig}}$, which indicates that the Collins-Soper-Sterman soft factor is not driving the evolution with the hard scale in nearly back-to-back dihadron and direct photon-hadron production in $p+p$ collisions. This behavior is in contrast to Drell-Yan and semi-inclusive deep-inelastic scattering measurements.

We study a holographic theory of general spacetimes that does not rely on the existence of asymptotic regions. This theory is to be formulated in a holographic space. When a semiclassical description is applicable, the holographic space is assumed to be a holographic screen: a codimension-1 surface that is capable of encoding states of the gravitational spacetime. Our analysis is guided by conjectured relationships between gravitational spacetime and quantum entanglement in the holographic description. To understand basic features of this picture, we catalog predictions for the holographic entanglement structure of cosmological spacetimes. We find that qualitative features of holographic entanglement entropies for such spacetimes differ from those in AdS/CFT but that the former reduce to the latter in the appropriate limit. The Hilbert space of the theory is analyzed, and two plausible structures are found: a direct-sum and “spacetime-equals-entanglement” structure. The former preserves a naive relationship between linear operators and observable quantities, while the latter respects a more direct connection between holographic entanglement and spacetime. We also discuss the issue of selecting a state in quantum gravity, in particular how the state of the multiverse may be selected in the landscape.

The surprising simplicity of Barvinsky-Nesterov or equivalently Gelfand-Yaglom methods of calculation of quantum determinants permits us to obtain compact expressions for a UV-finite difference of one-loop quantum energies for two arbitrary values of the parameter of the double-trace asymptotic boundary conditions. This result generalizes the Gubser and Mitra calculation for the particular case of difference of “regular” and “irregular” one-loop energies in the one-brane Randall-Sundrum model. The approach developed in the paper also allows us to get “in one line” the one-loop quantum energies in the two-brane Randall-Sundrum model. The relationship between “one-loop” expressions corresponding to the mixed Robin and to double-trace asymptotic boundary conditions is traced.

Dynamical solutions are always of interest to people in gravity theories. We derive a series of generalized Vaidya solutions in the $n$-dimensional de Rham-Gabadadze-Tolley massive gravity with a singular reference metric. Similar to the case of the Einstein gravity, the generalized Vaidya solution can describe shining/absorbing stars. Moreover, we also find a more general Vaidya-like solution by introducing a more generic matter field than the pure radiation in the original Vaidya spacetime. As a result, the above generalized Vaidya solution is naturally included in this Vaidya-like solution as a special case. We investigate the thermodynamics for this Vaidya-like spacetime by using the unified first law and present the generalized Misner-Sharp mass. Our results show that the generalized Minser-Sharp mass does exist in this spacetime. In addition, the usual Clausius relation $\delta Q=TdS$ holds on the apparent horizon, which implicates that the massive gravity is in a thermodynamic equilibrium state. We find that the work density vanishes for the generalized Vaidya solution, while it appears in the more general Vaidya-like solution. Furthermore, the covariant generalized Minser-Sharp mass in the $n$-dimensional de Rham-Gabadadze-Tolley massive gravity is also derived by taking a general metric ansatz into account.