Crucial questions about solar and supernova neutrinos remain unanswered. Super-Kamiokande has the exposure needed for progress, but detector backgrounds are a limiting factor. A leading component is the beta decays of isotopes produced by cosmic-ray muons and their secondaries, which initiate nuclear spallation reactions. Cuts of events after and surrounding muon tracks reduce this spallation decay background by $\simeq \hspace{0.17em}90\%$ (at a cost of $\simeq \hspace{0.17em}20\%$ deadtime), but its rate at 6–18 MeV is still dominant. A better way to cut this background was suggested in a Super-Kamiokande paper by Bays et al. [Phys. Rev. D 85, 052007 (2012)] on a search for the diffuse supernova neutrino background. They found that spallation decays above 16 MeV were preceded near the same location by a peak in the apparent Cherenkov light profile from the muon; a more aggressive cut was applied to a limited section of the muon track, leading to decreased background without increased deadtime. We put their empirical discovery on a firm theoretical foundation. We show that almost all spallation decay isotopes are produced by muon-induced showers and that these showers are rare enough and energetic enough to be identifiable. This is the first such demonstration for any detector. We detail how the physics of showers explains the peak in the muon Cherenkov light profile and other Super-K observations. Our results provide a physical basis for practical improvements in background rejection that will benefit multiple studies. For solar neutrinos, in particular, it should be possible to dramatically reduce backgrounds at energies as low as 6 MeV.

We compute critical exponents of $O(N)$ models in fractional dimensions between $d=2$ and 4, and for continuous values of the number of field components $N$, in this way completing the RG classification of universality classes for these models. These curves represent nonperturbative approximation to the exact results, they respect all the qualitative features expected from such quantities conciliating previously known perturbative results in three dimensions with exact results in two dimensions and giving a strong indication of what could be the exact behavior of such curves. We also report critical exponents for some multicritical universality classes in the cases $N\ge 2$ and $N=0$. Finally, in the large-$N$ limit our critical exponents correctly approach those of the spherical model, allowing us to set $N\sim 100$ as the threshold for the quantitative validity of leading order large-$N$ estimates.

We study cold dense quark matter and hybrid neutron stars with a Dyson-Schwinger quark model and various choices of the quark-gluon vertex. We obtain the equation of state of quark matter in beta equilibrium and investigate the hadron-quark phase transition in combination with a hadronic equation of state derived within the Brueckner-Hartree-Fock many-body theory. Comparing with the results for quark matter within the rainbow approximation, the Ball-Chiu (BC) Ansatz and the 1BC Ansatz for the quark-gluon vertex lead to a reduction of the effective interaction at finite chemical potential, qualitatively similar to the effect of our gluon propagator. We find that the phase transition and the equation of state of the quark or mixed phase and consequently the resulting hybrid star mass and radius depend mainly on a global reduction of the effective interaction due to effects of both the quark-gluon vertex and gluon propagator, but are not sensitive to details of the vertex Ansatz.

We show that Calabi-Yau manifolds are emergent from the commutative limit of six-dimensional noncommutative Hermitian $U(1)$ instantons. Therefore, we argue that the noncommutative Hermitian $U(1)$ instantons correspond to quantized Calabi-Yau manifolds.

Massive black hole binaries are the primary source of gravitational waves (GWs) for the future eLISA observatory. The detection and parameter estimation of these sources to high redshift would provide invaluable information on the formation mechanisms of seed black holes, and on the evolution of massive black holes and their host galaxies through cosmic time. The Fisher information matrix has been the standard tool for GW parameter estimation in the last two decades. However, recent studies have questioned the validity of using the Fisher matrix approach. For example, the Fisher matrix approach sometimes predicts errors of $\ge 100\%$ in the estimation of parameters such as the luminosity distance and sky position. With advances in computing power, Bayesian inference is beginning to replace the Fisher matrix approximation in parameter estimation studies. In this work, we conduct a Bayesian inference analysis for 120 sources situated at redshifts of between $0.1\le z\le 13.2$, and compare the results with those from a Fisher matrix analysis. The Fisher matrix results suggest that for this particular selection of sources, eLISA would be unable to localize sources at redshifts of $z\lesssim 6$. In contrast, Bayesian inference provides finite error estimations for all sources in the study, and shows that we can establish minimum closest distances for all sources. The study further predicts that we should be capable with eLISA, out to a redshift of at least $z\le 13$, of predicting a maximum error in the chirp mass of $\lesssim 1\%$, the reduced mass of $\lesssim 20\%$, the time to coalescence of 2 h, and to a redshift of $z\sim 5$, the inclination of the source with a maximum error of $\sim 60\mathrm{deg}$.

In the quark sector, we experience a correlation between the mixing angles and the mass ratios. A partial realization of the similar tie-up in the neutrino sector helps to constrain the parametrization of masses and mixing, and hints for a predictive framework. We derive five hierarchy dependent textures of neutrino mass matrix with minimum number of parameters ($\le 4$), following a model-independent strategy.

We explore a method developed in statistical physics which has been argued to have exponentially small finite-volume effects, in order to determine the critical temperature $T_{\mathrm{c}}$ of pure SU(3) gauge theory close to the continuum limit. The method allows us to estimate the critical coupling ${\beta }_c$ of the Wilson action for temporal extents up to $N_{\tau }\sim 20$ with $\lesssim 0.1\%$ uncertainties. Making use of the scale setting parameters $r_0$ and $\sqrt{t_0}$ in the same range of $\beta$-values, these results lead to the independent continuum extrapolations $T_{\mathrm{c}}{r}_0=0.7457(45)$ and $T_{\mathrm{c}}\sqrt{t_0}=0.2489(14)$, with the latter originating from a more convincing fit. Inserting a conversion of $r_0$ from literature (unfortunately with much larger errors) yields $T_{\mathrm{c}}/{\mathrm{\Lambda }}_{\overline{\mathrm{MS}}}=1.24(10)$.

We revisit the multicomponent leptonically decaying dark matter (DM) scenario to explain the possible electron/positron excesses with the recently updated AMS-02 data. We find that both the single- and two-component DM models can fit the positron fraction and $e^{+}/e^{-}$ respective fluxes, in which the two-component ones provide better fits. However, for the single-component models, the recent AMS-02 data on the positron fraction limit the DM cutoff to be smaller than 1 TeV, which conflicts with the high-energy behavior of the AMS-02 total $e^{+}+e^{-}$ flux spectrum, while the two-component DM models do not possess such a problem. We also discuss the constraints from the Fermi-LAT measurement of the diffuse $\gamma$-ray spectrum. We show that the two-component DM models are consistent with the current DM lifetime bounds. In contrast, the best-fit DM lifetimes in the single-component models are actually excluded.

Phenomenological aspects of simple dark matter models are studied. We discuss ways to discriminate the dark matter models in future experiments. We find that the measurements of the branching fraction of the Higgs boson into two photons, the electric dipole moment of the electron, and the direct-detection experiments are quite useful in discriminating particle models of dark matter. We also discuss the prospects of finding new particles in the dark sector at the LHC/ILC.

The Galactic center excess is explained in the framework of the Next-to-Minimal Supersymmetric Standard Model with a $Z_3$ discrete symmetry. We show that a resonant $CP$-odd Higgs boson with mass twice that of the Dark Matter (DM) candidate is favored. Meanwhile, the DM candidate is required to have relatively large coupling with the $Z$ boson through its Higgsino component in order to obtain correct DM relic density. Its LHC discovery potential via four signatures is discussed in detail. We find that the most sensitive signals are provided by the Higgsino-like chargino and neutralino pair production with their subsequent decays into $W$ bosons, $Z$ bosons, and DM. The majority of the relevant parameter space can be probed at the Large Hadron Collider with a center-of-mass energy of 14 TeV and an integrated luminosity $1000{\mathrm{fb}}^{-1}$.

Using the quark eigenmodes computed on the lattice with the overlap-Dirac operator, we investigate the spatial distribution of the chiral condensate around static color sources corresponding to quark-antiquark and three-quark systems. A flux structure of chromo fields appears in the presence of such color charges. The magnitude of the chiral condensate is reduced inside the color flux, which implies partial restoration of chiral symmetry inside hadrons. Taking a static baryon source in a periodic box as a toy model of nuclear matter, we estimate the magnitude of the chiral symmetry restoration as a function of baryon matter density.

We consider a light supersymmetric top-quark (top-squark) scenario, where a top squark and a neutralino are the lightest supersymmetric particles and the top-squark mass is close to the sum of the neutralino mass and the top-quark mass. In this scenario, the top quark and the neutralino coming from the decay of a top squark have almost equal velocity vectors, and hence the missing transverse momentum in top-squark pair production events at colliders is suppressed, which makes the top-squark search challenging, as in the degenerate scenario where the top-squark mass and the neutralino mass are similar. In this paper, we propose a novel analysis technique aimed at discovering the top-squark pair production signal in such an “equal-velocity” scenario. The key is to look for events where the missing transverse momentum vector is proportional to the transverse momentum vector of the top-quark pair with specific values for the proportionality coefficient, as this coefficient is equal to the ratio of the neutralino mass over the top-quark mass in the equal-velocity limit. We examine the possibility that the top-squark signal can be identified at the $\sqrt{s}=14\mathrm{TeV}$ LHC using our analysis method.

We consider backward vector meson exclusive electroproduction off nucleons in the framework of collinear QCD factorization. Nucleon to vector meson transition distribution amplitudes (TDAs) arise as building blocks for the corresponding factorized amplitudes. In the near-backward kinematics, the suggested factorization mechanism results in the dominance of the transverse cross section of vector meson production (${\sigma }_T\gg {\sigma }_L$) and in the characteristic $1/Q^8$-scaling behavior of the cross section. We evaluate nucleon to vector meson TDAs in the cross-channel nucleon exchange model and present estimates of the differential cross section for backward ${\rho }^0$, $\omega$ and $\varphi$ meson production off protons. The resulting cross sections are shown to be measurable in the forthcoming JLab@12 GeV experiments.

We present for the first time the full automation of collider predictions matched with parton showers at the next-to-leading accuracy in QCD within nontrivial extensions of the standard model. The sole inputs required from the user are the model Lagrangian and the process of interest. As an application of the above, we explore scenarios beyond the standard model where new colored scalar particles can be pair produced in hadron collisions. Using simplified models to describe the new field interactions with the standard model, we present precision predictions for the LHC within the MadGraph5_aMC@NLO framework.

We study the masses and wave functions of heavy-light quark-antiquark system in the relativistic potential model, where we focus on the higher excited states of $B$ and $D$ mesons. The resonances of $D_J(2740)$, $D_J^{*}(2760)$, $D_J^{*}(3000)$, and $D_{sJ}^{*}(2860)$ recently observed in experiments are considered. We find that these four resonances can be identified as the $|1{{}^{1,3}D}_2⟩$, $|1{{}^{3}D}_3⟩$, $|1{{}^{1,3}F}_3⟩$, and $|1{{}^{3}D}_3⟩$ states due to the prediction to the states with $l=2$ and $l=3$ in the potential-model calculation. The masses of $n=2$ excited states are also calculated. All the observed mesons can be accommodated successfully in the potential model.

We present results from the analytic calculation of $t\overline{t}H$ hadronic production at next-to-leading order in QCD interfaced with parton-shower Monte Carlo event generators in the POWHEG BOX framework. We consider kinematic distributions of the top quark and Higgs boson at the 8 TeV Large Hadron Collider and study the theoretical uncertainties due to specific choices of renormalization/factorization scales and parton-showering algorithms, namely PYTHIA and HERWIG. The importance of spin correlations in the production and decay stages of a top/antitop quark is discussed on the example of kinematic distributions of leptons originating from the top/antitop decays. The corresponding code is now part of the public release of the POWHEG BOX.

The search for ${\nu }_{\mu }\to {\nu }_e$ oscillations by the MiniBooNE Collaboration at Fermilab has revealed a low-energy signal which could be due either to electrons produced by ${\nu }_e$ or photons produced by the interaction of the weak neutral current on the target nucleus. One contribution to the latter is a Wess-Zumino-Witten anomaly leading to a term in the Lagrangian proportional to ${\epsilon }^{\mu \nu \kappa \lambda }{Z}_{\mu }{\omega }_{\nu }{F}_{\kappa \lambda }$. This term is normalized with the help of the known rates for the processes $f_1\to \rho \gamma$ and $\tau \to {\nu }_{\tau }{a}_1$. A rate of about $1/4$ of that employed in several previous estimates is obtained. As the anomaly term had already been found to play a subdominant role in photon production (e.g., in comparison with $\mathrm{\Delta }$ excitation and decay), the present estimate reduces its strength even further.