Monoenergetic muon neutrinos (235.5 MeV) from positive kaon decay at rest are considered as a source for an electron neutrino appearance search. In combination with a liquid argon time projection chamber based detector, such a source could provide discovery-level sensitivity to the neutrino oscillation parameter space ($\Delta m^2\sim 1{\mathrm{eV}}^2$) indicative of a sterile neutrino. Current and future intense $\gtrsim 3\mathrm{GeV}$ kinetic energy proton facilities around the world can be employed for this experimental concept.

We consider the holographic prescription problem in a (Lorentzian) AdS background, deriving from first principles the explicit formulas that relate the field at infinity with the field in the bulk. In contrast with the previous studies of the “real-time” holography problem, our derivation uses purely classical arguments that involve causality, as in the usual treatment of the holographic prescription problem in Wick-rotated spaces of Euclidean signature. We show that there is a unique propagator that preserves causality and see that this provides a simple picture of the relationship between the bulk manifold and its conformal boundary.

“$\theta$-angle monodromy” occurs when a theory possesses a landscape of metastable vacua which reshuffle as one shifts a periodic coupling $\theta$ by a single period. “Axion monodromy” models arise when this parameter is promoted to a dynamical pseudoscalar field. This paper studies the phenomenon in two-dimensional gauge theories which possess a $U(1)$ factor at low energies: the massive Schwinger and gauged massive Thirring models, the $U(N)$ ’t Hooft model, and the $\mathbb{C}{P}^N$ model. In all of these models, the energy dependence of a given metastable false vacuum deviates significantly from quadratic dependence on $\theta$ just as the branch becomes completely unstable (distinct from some four-dimensional axion monodromy models). In the Schwinger, Thirring, and ’t Hooft models, the meson masses decrease as a function of $\theta$. In the $U(N)$ models, the landscape is enriched by sectors with non-Abelian $\theta$ terms. In the $\mathbb{C}{P}^N$ model, we compute the effective action and the size of the mass gap is computed along a metastable branch.

In this paper we compute stringent astrophysical and cosmological constraints on a recently proposed Eddington-inspired Born-Infeld theory of gravity. We find, using a generalized version of the Zel’dovich approximation, that in this theory a pressureless, cold-dark matter fluid has a nonzero effective sound speed. We compute the corresponding effective Jeans length and show that it is approximately equal to the fundamental length of the theory $R_{*}={\kappa }^{1/2}{G}^{-1/2}$, where $\kappa$ is the only additional parameter of theory with respect to general relativity and $G$ is the gravitational constant. This scale determines the minimum size of compact objects which are held together by gravity. We also estimate the critical mass above which pressureless compact objects are unstable against collapse into a black hole, showing that it is approximately equal to the fundamental mass $M_{*}={\kappa }^{1/2}{c}^2{G}^{-3/2}$, and we show that the maximum density attainable inside stable compact stars is roughly equal to the fundamental density ${\rho }_{*}={\kappa }^{-1}{c}^2$, where $c$ is the speed of light in vacuum. We find that the mere existence of astrophysical objects of size $R$, which are held together by their own gravity, leads to the constraint $\kappa <G{R}^2$. In the case of neutron stars this implies that $\kappa <{10}^{-2}{\mathrm{m}}^5{\mathrm{kg}}^{-1}{\mathrm{s}}^{-2}$, a limit which is stronger by about 10 orders of magnitude than big bang nucleosynthesis constraints and by more than 7 orders of magnitude than solar constraints.

We use dimensional regularization to compute the one loop quantum gravitational contribution to the vacuum polarization on flat space background. Adding the appropriate Bogoliubov-Parsiuk-Hepp-Zimmermann counterterm gives a fully renormalized result which we employ to quantum correct Maxwell’s equations. These equations are solved to show that dynamical photons are unchanged, provided the free state wave functional is appropriately corrected. The response to the instantaneous appearance of a point dipole reveals a perturbative version of the long-conjectured, “smearing of the light cone”. There is no change in the far radiation field produced by an alternating dipole. However, the correction to the static electric field of a point charge shows strengthening at short distances, in contrast to expectations based on the renormalization group. We check for gauge dependence by working out the vacuum polarization in a general 3-parameter family of covariant gauges.

The observational relation between the density of baryon and dark matter in the Universe, ${\Omega }_{\mathrm{DM}}/{\Omega }_B\simeq 5$, is one of the most difficult problems to solve in modern cosmology. We discuss a scenario that explains this relation by combining the asymmetric dark matter scenario and the spontaneous baryogenesis associated with the flat direction in the supersymmetric standard model. A part of baryon asymmetry is transferred to charge asymmetry $D$ that dark matter carries, if a symmetry violating interaction that works at high temperature breaks not only $B\mathrm{\text{−}}L$ but also $D$ symmetries simultaneously. In this case, the present number density of baryon and dark matter can be same order if the symmetric part of dark matter annihilates sufficiently. Moreover, the baryon number density can be enhanced as compared to that of dark matter if another $B\mathrm{\text{−}}L$ violating interaction is still in thermal equilibrium after the spontaneous genesis of dark matter, which accommodates a TeV scale asymmetric dark matter model.

We compute various processes involving neutrinos in the initial and/or final state, and we assume that neutrinos have energy momentum relation with a general power law $E^2=p^2+{\xi }_n{p}^n$ correction due to Lorentz invariance violation. We find that for $n>2$, the bounds on ${\xi }_n$ from direct time of flight measurement are much more stringent than from constraining the neutrino Čerenkov decay process.

We investigate the phase of the quark determinant with finite chemical potential in lattice QCD using both analytic and numerical methods. Applying the winding expansion and the hopping parameter expansion to the logarithm of the determinant, we show that the absolute value of the phase has an upper bound that grows with the spatial volume but decreases exponentially with an increase in the temporal extent of the lattice. This analytic but approximate result is confirmed with a numerical study in four-flavor QCD in which the phase is calculated exactly. Since the phase is well controlled on lattices with larger time extents, we try the phase reweighting method in a region beyond $\mu /T=1$ where the Taylor expansion method cannot be applied. Working in four-flavor QCD, we find a first-order like behavior on a $6^3\times 4$ lattice at $\mu /T\approx 0.8$ which was previously observed by the Kentucky group with the canonical method. We also show that the winding expansion has a nice convergence property beyond $\mu /T=1$. We expect that this expansion is useful to study the high density region of the QCD phase diagram at low temperatures.

The factorization theorem for exclusive processes in perturbative QCD predicts the behavior of the pion electromagnetic form factor $F(t)$ at asymptotic spacelike momenta $t(=-Q^2)<0$. We address the question of the onset energy using a suitable mathematical framework of analytic continuation, which uses as input the phase of the form factor below the first inelastic threshold, known with great precision through the Fermi-Watson theorem from $\pi \pi$ elastic scattering, and the modulus measured from threshold up to 3 GeV by the BABAR Collaboration. The method leads to almost model-independent upper and lower bounds on the spacelike form factor. Further inclusion of the value of the charge radius and the experimental value at $-2.45{\mathrm{GeV}}^2$ measured at JLab considerably increases the strength of the bounds in the region $Q^2\lesssim 10{\mathrm{GeV}}^2$, excluding the onset of the asymptotic perturbative QCD regime for $Q^2<7{\mathrm{GeV}}^2$. We also compare the bounds with available experimental data and with several theoretical models proposed for the low and intermediate spacelike region.

Doubly charged Higgs bosons are predicted in many new physics models with an extended Higgs sector that contains a Higgs triplet field. Current experimental searches have been focusing mainly on the scenario in which the same-sign dilepton decay modes are the dominant ones. We study the scenario where the vacuum expectation value of the triplet field is sufficiently large so that the associated charged Higgs bosons decay dominantly to a pair of weak gauge bosons instead. A detailed simulation of the signal and the backgrounds is performed for the CERN Large Hadron Collider (LHC) at the collision energy of 8 TeV and 14 TeV. We find that different cuts should be imposed for the events, depending on whether the doubly charged Higgs boson mass is greater than about 200 GeV. In the higher mass region, the forward jet tagging proves to be useful in enhancing the signal significance. We show the discovery reach of the LHC running at 8 and 14 TeV, with two benchmark triplet vacuum expectation values. With an integrated luminosity of $10{\mathrm{fb}}^{-1}$ at 8 TeV, the doubly charged Higgs boson with a mass of $\sim 180\mathrm{GeV}$ can be tested at $5\sigma$ level in such a scenario.

We determine the (pseudo)critical lines of QCD with two degenerate staggered fermions at nonzero temperature and quark or isospin density, in the region of imaginary chemical potentials; analytic continuation is then used to prolongate to the region of real chemical potentials. We obtain an accurate determination of the curvatures at zero chemical potential, quantifying the deviation between the case of finite quark and of finite isospin chemical potential. Deviations from a quadratic dependence of the pseudocritical lines on the chemical potential are clearly seen in both cases: we try different extrapolations and, for the case of nonzero isospin chemical potential, confront them with the results of direct Monte Carlo simulations. Finally we find that, as for the finite quark density case, an imaginary isospin chemical potential can strengthen the transition until turning it into strong first order.

We explore the interactions of two strangeness $-3$ baryons in multiple spin channels with lattice QCD. This system provides an ideal laboratory for exploring the interactions of multibaryon systems with minimal dependence on light-quark masses. Model calculations of the two-${\Omega }^{-}$ system in two previous works have obtained conflicting results, which can be resolved by lattice QCD. The lattice calculations are performed using two different volumes with $L\sim 2.5$ and 3.9 fm on anisotropic clover lattices at $m_{\pi }\sim 390\mathrm{MeV}$ with a lattice spacing of $a_s\sim 0.123\mathrm{fm}$ in the spatial direction and $a_t\sim a_s/3.5$ in the temporal direction. Using multiple interpolating operators from a nondisplaced source, we present scattering information for two ground state ${\Omega }^{-}$ baryons in both the $S=0$ and $S=2$ channels. For $S=0$, $k\cot \delta$ is extracted at two volumes, which lead to an extrapolated scattering length of $a_{S=0}^{\Omega \Omega }=0.16\pm 0.22\mathrm{fm}$, indicating a weakly repulsive interaction. Additionally, for $S=2$, two separate highly repulsive states are observed. We also present results on the interactions of the excited strangeness $-3$, spin-$\frac{1}{2}$ states with the ground spin-$\frac{3}{2}$ states for the spin-1 and spin-2 channels. Results for these interactions are consistent with attractive behavior.

We discuss production of two pairs of $c\overline{c}$ within a simple formalism of double-parton scattering. Surprisingly very large cross sections, comparable to single-parton scattering single $c\overline{c}$ pair production contribution, are predicted for LHC energies. Both the total inclusive cross section as a function of energy and differential distributions in rapidity and transverse momentum of charm quark/antiquark as well as some correlation distributions for $\sqrt{s}=7\mathrm{TeV}$ are shown. We have presented results for commonly used factorized Ansatz and with QCD-evolved double-parton distributions as discussed recently in the literature. The difference found between results of the naive and QCD refined approaches is found to be rather small. We discuss perspectives on how to identify the double-scattering contribution. The region of the phase space when $cc$, $\overline{c}\overline{c}$, $c\overline{c}$ are produced with a large rapidity interval between them is potentially very promising. We have compared the results of the double- and single-scattering $c\overline{c}c\overline{c}$ pair production mechanisms. The contribution of the latter mechanism is much smaller. A good signature of the $c\overline{c}c\overline{c}$ production is e.g. a measurement of two identical $D^0{D}^0$ or ${\overline{D}}^0{\overline{D}}^0$ mesons in one event. Predictions for ATLAS, CMS, ALICE, and LHCb are presented. Other options of possible measurements are discussed.

Some long-standing problems in the experimental data for semileptonic $b\to c\ell \overline{\nu }$ decay rates have resisted attempts to resolve them, despite substantial efforts. We summarize the issues, and propose a possible resolution, which may alleviate several of these tensions simultaneously, including the “$1/2$ vs $3/2$ puzzle” and the composition of the inclusive decay rate in terms of exclusive channels.

The most recent results of searches at the LHC for the Higgs boson $h$ have turned up possible hints of such a particle with mass $m_h$ about 125 GeV consistent with standard model (SM) expectations. This has many potential implications for the SM and beyond. We consider some of them in the contexts of a simple Higgs-portal dark matter (DM) model, the SM plus a real gauge-singlet scalar field $D$ as the DM candidate, and a couple of its variations. In the simplest model with one Higgs doublet and three or four generations of fermions, for $D$ mass $m_D<m_h/2$ the invisible decay $h\to DD$ tends to have a substantial branching ratio. If future LHC data confirm the preliminary Higgs indications, $m_D$ will have to exceed $m_h/2$. To keep the DM lighter than $m_h/2$, one will need to extend the model and also satisfy constraints from DM direct searches. The latter can be accommodated if the model provides sizable isospin violation in the DM-nucleon interactions. We explore this in a two-Higgs-doublet model combined with the scalar field $D$. This model can offer a 125 GeV SM-like Higgs and a light DM candidate having isospin-violating interactions with nucleons at roughly the required level, albeit with some degree of fine-tuning.

We discuss the possibility of observing multi-lepton signals at the Large Hadron Collider (LHC) from the production and decay of heavy standard model (SM) singlet neutrinos added in extensions of SM to explain the observed light neutrino masses by seesaw mechanism. In particular, we analyze two “smoking gun” signals depending on the Dirac or Majorana nature of the heavy neutrino: (i) for Majorana case, the same-sign di-lepton signal which can be used as a probe of lepton-number violation, and (ii) for Dirac case, the tri-lepton signal which conserves lepton number but may violate lepton flavor. Within a minimal Left-Right symmetric framework in which these additional neutrino states arise naturally, we find that in both cases, the signals can be identified with virtually no background beyond a TeV, and the heavy gauge boson $W_R$ can be discovered in this process. This analysis also provides a direct way to probe the nature of seesaw physics involving the SM singlets at TeV-scale, and in particular, to distinguish type-I seesaw with purely Majorana heavy neutrinos from inverse seesaw with pseudo-Dirac counterparts.

A significant signal of neutrinoless double beta decay can be consistent with the existence of light quasi-Dirac neutrinos. To demonstrate this possibility, we consider a realistic model where the neutrino masses and the neutrinoless double beta decay can be simultaneously generated after a Peccei-Quinn symmetry breaking.

We present results for $B$-meson decay modes involving a charm meson, protons, and pions using $455\times {10}^6$ $B\overline{B}$ pairs recorded by the BaBar detector at the SLAC PEP-II asymmetric-energy $e^{+}{e}^{-}$ collider. The branching fractions are measured for the following ten decays: ${\overline{B}}^0\to D^{0}p\overline{p}$, ${\overline{B}}^0\to D^{*0}p\overline{p}$, ${\overline{B}}^0\to D^{+}p\overline{p}{\pi }^{-}$, ${\overline{B}}^0\to D^{*+}p\overline{p}{\pi }^{-}$, $B^{-}\to D^{0}p\overline{p}{\pi }^{-}$, $B^{-}\to D^{*0}p\overline{p}{\pi }^{-}$, ${\overline{B}}^0\to D^{0}p\overline{p}{\pi }^{-}{\pi }^{+}$, ${\overline{B}}^0\to D^{*0}p\overline{p}{\pi }^{-}{\pi }^{+}$, $B^{-}\to D^{+}p\overline{p}{\pi }^{-}{\pi }^{-}$, and $B^{-}\to D^{*+}p\overline{p}{\pi }^{-}{\pi }^{-}$. The four $B^{-}$ and the two five-body ${\overline{B}}^0$ modes are observed for the first time. The four-body modes are enhanced compared to the three- and the five-body modes. In the three-body modes, the $M(p\overline{p})$ and $M(D^{(*)0}p)$ invariant-mass distributions show enhancements near threshold values. In the four-body mode ${\overline{B}}^0\to D^{+}p\overline{p}{\pi }^{-}$, the $M(p{\pi }^{-})$ distribution shows a narrow structure of unknown origin near $1.5\mathrm{GeV}/c^2$. The distributions for the five-body modes, in contrast to the others, are similar to the expectations from uniform phase-space predictions.

We present both spin-independent and spin-dependent parts of a central interquark potential for charmonium states, which is calculated in $2+1$ flavor dynamical lattice QCD using the PACS-CS gauge configurations with a lattice cutoff of $a^{-1}\approx 2.2\mathrm{GeV}$. Our simulations are performed with a relativistic heavy-quark action for the charm quark at the lightest pion mass, $M_{\pi }=156(7)\mathrm{MeV}$, in a spatial volume of $(3\mathrm{fm}{)}^3$. We observe that the spin-independent charmonium potential obtained from lattice QCD with almost physical quark masses is quite similar to the Cornell potential used in nonrelativistic potential models. The spin-spin potential, which is calculated in full lattice QCD for the first time, properly exhibits a finite-range repulsive interaction. Its $r$-dependence is different from the Fermi-Breit type potential, which is widely adopted in quark potential models.

The Einstein-Cartan-Sciama-Kibble theory of gravity removes the constraint of general relativity that the affine connection be symmetric by regarding its antisymmetric part, the torsion tensor, as a dynamical variable. The minimal coupling between the torsion tensor and Dirac spinors generates a spin-spin interaction which is significant in fermionic matter at extremely high densities. We show that such an interaction averts the unphysical big-bang singularity, replacing it with a cusp-like bounce at a finite minimum scale factor, before which the Universe was contracting. This scenario also explains why the present Universe at largest scales appears spatially flat, homogeneous and isotropic.