Recent results from the SNO, Super-Kamiokande, and Borexino experiments do not show the expected upturn of the energy spectrum of events (the ratio $R\equiv N_{\mathrm{obs}}/N_{\mathrm{SSM}}$) at low energies. At the same time, cosmological observations testify for the possible existence of additional relativistic degrees of freedom in the early Universe: $\Delta N_{\mathrm{eff}}=1–2$. These facts strengthen the case of a very light sterile neutrino, ${\nu }_s$, with $\Delta m_{01}^2\sim (0.7–2)\times {10}^{-5}{\mathrm{eV}}^2$, which mixes weakly with the active neutrinos. The ${\nu }_s$ mixing in the mass eigenstate ${\nu }_1$ characterized by ${sin}^{2}2\alpha \sim {10}^{-3}$ can explain an absence of the upturn. The mixing of ${\nu }_s$ in the eigenstate ${\nu }_3$ with ${sin}^2\beta \sim 0.1$ leads to production of ${\nu }_s$ via oscillations in the Universe and to additional contribution $\Delta N_{\mathrm{eff}}\approx 0.7–1$ before the big bang nucleosynthesis and later. Such a mixing can be tested in forthcoming experiments with the atmospheric neutrinos, as well as in future accelerator long baseline experiments. It has substantial impact on conversion of the supernova neutrinos.

Ruling out the inverted neutrino hierarchy with neutrinoless double beta decay experiments is possible if a limit on the effective mass below the minimal theoretically possible value is reached. We stress that this lower limit depends strongly on the value of the solar neutrino mixing angle: it introduces an uncertainty of a factor of 2 within its current $3\sigma$ range. If an experiment is not background-free, a factor of 2 in effective mass corresponds to a combined factor of 16 improvement for the experimental parameters running time, detector mass, background level, and energy resolution. Therefore, a more precise determination of ${\theta }_{12}$ is crucial for the interpretation of experimental results and the evaluation of the potential and requirements for future experiments. We give the required half-lives to exclude (and touch) the inverted hierarchy regime for all double beta decay isotopes with a $Q$ value above 2 MeV. The nuclear matrix elements from 6 different groups and, if available, their errors are used and compared. We carefully put the calculations on equal footing in what regards various convention issues. We also use our compilation of matrix elements to give the reachable values of the effective mass for a given half-life value.

We present a new calculation of the cross sections for charged current and neutral current $\nu N$ and $\overline{\nu }N$ interactions in the neutrino energy range ${10}^4<E_{\nu }<{10}^{12}\mathrm{GeV}$ using the most recent Martin-Stirling-Thorne-Watt (MSTW) parton distribution functions (PDFs), MSTW 2008. We also present the associated uncertainties propagated from the PDFs, as well as parametrizations of the cross section central values, their uncertainty bounds, and the inelasticity distributions for ease of use in Monte Carlo simulations. For the latter we only provide parametrizations for energies above ${10}^7\mathrm{GeV}$. Finally, we assess the feasibility of future neutrino experiments to constrain the $\nu N$ cross section in the ultrahigh energy regime using a technique that is independent of the flux spectrum of incident neutrinos. A significant deviation from the predicted standard model cross sections could be an indication of new physics, such as extra space-time dimensions, and we present expected constraints on such models as a function of the number of events observed in a future subterranean neutrino detector.

We report on a search for anomalous production of $Z$ boson pairs through a massive resonance decay in data corresponding to $2.5–2.9{\mathrm{fb}}^{-1}$ of integrated luminosity in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ using the CDF II detector at the Fermilab Tevatron. This analysis, with more data and channels where the $Z$ bosons decay to muons or jets, supersedes the $1.1{\mathrm{fb}}^{-1}$ four-electron channel result previously published by CDF. In order to maintain high efficiency for muons, we use a new forward tracking algorithm and muon identification requirements optimized for these high signal-to-background channels. Predicting the dominant backgrounds in each channel entirely from sideband data samples, we observe four-body invariant mass spectra above $300\mathrm{GeV}/c^2$ that are consistent with background. We set limits using the acceptance for a massive graviton resonance that are 7–20 times stronger than the previously published direct limits on resonant $ZZ$ diboson production.

We discuss the issue of fermion mass hierarchies between lepton and quark families in toy models of dynamical generation of fermion masses through minimal Lorentz invariance violation. Realistic hierarchies in chiral theories necessitate an extended gauge structure, which includes both vector and axial-vector interactions.

We explore maximally supersymmetric Yang-Mills theory with walls of impurities respecting half of the supersymmetries. The walls carry fundamental or bifundamental matter multiplets. We employ three-dimensional $\mathcal{N}=2$ superspace language to identify the Higgs branch of this theory. We find that the vacuum conditions determining the Higgs branch are exactly the bow equations yielding Yang-Mills instantons on a multi-Taub-NUT space. Under electric-magnetic duality, the super Yang-Mills theory describing the bulk is mapped to itself, while the fundamental- and bifundamental-carrying impurity walls are interchanged. We perform a one-loop computation on the Coulomb branch of the dual theory to find the asymptotic metric on the original Higgs branch.

We study the breaking of an Abelian symmetry close to the horizon of a black string as well as close to the tip of a solitonic, cigar-shaped solution in ($3+1$)-dimensional anti-de Sitter space-time. We use these solutions to describe holographic superfluids away from the probe limit, i.e. taking backreaction into account. We observe that up to four phases exist in this model representing the duals of black string solutions with and without scalar hair and solitonic, cigar-shaped solutions with and without scalar hair, respectively. We construct the full phase diagram that describes the phase transitions between fluids and superfluids, between insulators and superfluids, as well as between insulators and fluids. In the probe limit the phase transition from fluids to black string superfluids changes from being second order to first order for sufficiently large values of the superfluid velocity and/or the angular momentum of the dual black string. We find that if we take backreaction into account phase transitions that are first order for weak backreaction become again second order for sufficiently strong backreaction. Moreover, we find a new type of insulator/superfluid phase transition for strong backreaction and vanishing superfluid velocity as well as a new type of fluid/superfluid phase transition that exists only for nonvanishing superfluid velocity.

We study the renormalization-group (RG) flow of two dimensional (fluid) membranes embedded in Euclidean $D$-dimensional space using functional RG methods based on the effective average action. By considering a truncation ansatz for the effective average action with both extrinsic and intrinsic curvature terms, we derive a system of beta functions for the running surface tension ${\mu }_k$, bending rigidity ${\kappa }_k$, and Gaussian rigidity ${\overline{\kappa }}_k$. We look for nontrivial fixed points but we find no evidence for a crumpling transition at $T\ne 0$. Finally, we propose to identify the $D\to 0$ limit of the theory with two dimensional quantum gravity. In this limit, we derive new beta functions for both cosmological and Newton’s constants.

In this paper we reconsider the derivation of anomaly mediated supersymmetry breaking. We work in a general formalism where the $F$ term of the conformal compensator superfield is arbitrary. This allows for a continuous interpolation between the original derivation and a more recent Dine-Seiberg derivation of anomaly mediation. We show that the physical soft parameters are independent of the compensator $F$ term and results of two formalisms agree. Finally, we discuss the role of supersymmetric and nonsupersymmetric thresholds in the effective low-energy Lagrangian as well as the effects of explicit small mass parameters (such as $\mu$ term) on the superpartner spectrum.

We have investigated several properties of rapidly rotating dynamic black holes generated by the gravitational collapse of rotating relativistic stars. At present, numerical simulations of the binary black hole merger are able to produce a Kerr black hole of $J_{\mathrm{final}}/M_{\mathrm{final}}^2$ up to $=0.91$, of gravitational collapse from uniformly rotating stars up to $J_{\mathrm{final}}/M_{\mathrm{final}}^2\approx 0.75$, where $J_{\mathrm{final}}$ is the total angular momentum and $M_{\mathrm{final}}$ the total gravitational mass of the hole. We have succeeded in producing a dynamic black hole of spin $J_{\mathrm{final}}/M_{\mathrm{final}}^2\approx 0.95$ through the collapse of differentially rotating relativistic stars. We have investigated those dynamic properties through diagnosing multipole moment of the horizon, and found the following two features. First, two different definitions of the angular momentum of the hole, the approximated Killing vector approach and dipole moment of the current multipole approach, make no significant difference to our computational results. Second, dynamic hole approaches a Kerr by gravitational radiation within the order of a rotational period of an equilibrium star, although the dynamic hole at the very forming stage deviates quite far from a Kerr. We have also discussed a new phase of quasi-periodic waves in the gravitational waveform after the ringdown in terms of the multipole moment of the dynamic hole.

With the Cowling approximation, the torsional oscillations on relativistic stars in tensor-vector-scalar (TeVeS) theory are examined. The spectrum features in TeVeS are very similar to those in general relativity (GR), but the torsional frequencies in TeVeS become larger than those expected in GR. We find that, compared with the fluid oscillations with polar parity, the torsional frequencies depend strongly on the gravitational theory. Since the dependencies of fundamental frequencies on the gravitational theory and on the equation of state are different from those of overtone, it could be possible to distinguish TeVeS from GR in the strong-field regime via observations of this type of oscillations with the help of the observation of stellar mass.

In dynamic spacetimes in which asymmetric gravitational collapse/expansion is taking place, the timelike geodesic equation appears to exhibit an interesting property: Relative to the collapsing configuration, free test particles undergo gravitational “acceleration” and form a double-jet configuration parallel to the axis of collapse. We illustrate this aspect of peculiar motion in simple spatially homogeneous cosmological models such as the Kasner spacetime. To estimate the effect of spatial inhomogeneities on cosmic jets, timelike geodesics in the Ricci-flat double-Kasner spacetime are studied in detail. While spatial inhomogeneities can significantly modify the structure of cosmic jets, we find that under favorable conditions the double-jet pattern can initially persist over a finite period of time for sufficiently small inhomogeneities.

The legacy of solar neutrinos suggests that large neutrino detectors should be sited underground. However, to instead go underwater bypasses the need to move mountains, allowing much larger water Čerenkov detectors. We show that reaching a detector mass scale of $\sim 5$ Megatons, the size of the proposed Deep-TITAND, would permit observations of neutrino “mini-bursts” from supernovae in nearby galaxies on a roughly yearly basis, and we develop the immediate qualitative and quantitative consequences. Importantly, these mini-bursts would be detected over backgrounds without the need for optical evidence of the supernova, guaranteeing the beginning of time-domain MeV neutrino astronomy. The ability to identify, to the second, every core collapse in the local Universe would allow a continuous “death watch” of all stars within $\sim 5\mathrm{Mpc}$, making practical many previously-impossible tasks in probing rare outcomes and refining coordination of multiwavelength/multiparticle observations and analysis. These include the abilities to promptly detect otherwise-invisible prompt black hole formation, provide advance warning for supernova shock-breakout searches, define tight time windows for gravitational-wave searches, and identify “supernova impostors” by the nondetection of neutrinos. Observations of many supernovae, even with low numbers of detected neutrinos, will help answer questions about supernovae that cannot be resolved with a single high-statistics event in the Milky Way.

We consider a model where neutrinos interact with weakly interacting massive particles (WIMPs) as a possible explanation for the production of NuTeV’s anomalous dimuon events. This model naturally produces the features reported by NuTeV, specifically the muon energy asymmetry and other kinematics. When combined with the NuTeV event selection criteria, this model predicts an expectation of zero events as observed in their other search channels. For the best agreement with data, the model requires a lower WIMP mass than conventionally expected, but one that is of current interest due to DAMA/LIBRA results, at around $10\mathrm{GeV}/c^2$. This model has a very high cross section for neutrino-WIMP interactions. We make suggestions for future searches that would confirm or refute this model.

In this letter, we investigate the production of light dark matter particles at LHC in a $N=2$ SUSY inspired model and demonstrate that particles will be copiously produced if the colored messengers $F_q$ are lighter than 1 TeV. We expect up to ${10}^6$ events if $m_{F_q}\simeq 500\mathrm{GeV}$, assuming a $\sim 1{\mathrm{fb}}^{-1}$ luminosity. In addition, we show that, even if $m_{F_q}>\mathcal{O}(1)\mathrm{TeV}$, searches for $F_q$ production at LHC are promising because a kinematical signature can be used to separate the signal from background. This signature is similar to that expected in supersymmetric scenarios. Hence, our study shows that most of the $m_{F_q}$ range could be constrained using LHC data. This should encourage further studies since they could infirm/confirm the MeV DM scenario.

We make use of twisted boundary conditions for off-shell, Rome-Southampton renormalization. This allows us to define vertex functions at a fixed physical momentum that need not be a Fourier mode. This definition includes choosing a fixed orientation with respect to the lattice axes; only then do lattice artifacts, which include $O(4)$ breaking effects, have a valid expansion in powers of the lattice spacing, $a$. The use of nonexceptional momenta has been found to greatly reduce the dependence of the vertex functions on both mass and momentum, $p$. Excellent statistical precision is afforded by plane-wave sources. Together this enables both a theoretically well-founded and statistically clean continuum limit. Thereafter all $p^2$ dependence can be identified with the anomalous running of the operator. We present initial results and develop a practical scheme for step-scaling with off-shell renormalization. The size of the steps is continuous rather than discrete, allowing arbitrarily small steps and the scheme is easy to implement for general operators.

${\chi }_{cJ}$ ($J=0$, 1, 2) production associated with a charm quark pair in hadron collisions is calculated in the framework of nonrelativistic QCD at the Tevatron and LHC. It is found that the color-singlet contribution is small and the color-octet contribution may be dominant in the large $p_T$ region. The differential cross section of $p\overline{p}\to {\chi }_c+c\overline{c}$ is at least 1 order of magnitude smaller than the next-to-leading order result of ${\chi }_{cJ}$ inclusive production $p\overline{p}\to {\chi }_c+X$; therefore ${\chi }_{cJ}$ production in $p\overline{p}\to {\chi }_c+c\overline{c}$ may have negligible influence on the ratio $R_{{\chi }_c}=\frac{{\sigma }_{{\chi }_{c2}}}{{\sigma }_{{\chi }_{c1}}}$ measured by CDF Collaboration at the Tevatron. The feed-down contribution from ${\chi }_{cJ}+c+\overline{c}$ to $J/\psi +c+\overline{c}$ is found to be large compared with $J/\psi$ direct production and may have important influence on the measurement of $J/\psi +c+\overline{c}$. The validity of fragmentation approximation for the process is also discussed.

Discussing the general case of a hard partonic production process, we show that the notion of parton energy loss is not always sufficient to fully address medium-induced gluon radiation. The broader notion of gluon radiation associated with a hard process has to be used, in particular, when initial and final-state radiation amplitudes interfere, making the medium-induced radiated energy different from the energy loss of any well-identified parton. Our arguments are first presented in an Abelian QED model, and then applied to large-$x_F$ quarkonium hadroproduction. In this case, we show that the medium-induced radiated energy is qualitatively similar (but not identical) to the radiative energy loss of an “asymptotic massive parton” undergoing transverse momentum broadening when travelling through the nucleus. In particular, it scales as the incoming parton energy, which suggests that gluon radiation should be reconsidered as a possible explanation of large $x_F$ quarkonium suppression in $p\mathrm{\text{−}}A$ collisions. We expect a similar effect in open heavy-flavor and possibly light-hadron hadroproduction at large $x_F$.

The computation of the $\mathcal{O}({\alpha }_s)$ QCD corrections to the cross sections for $W^{\pm }\gamma \gamma$ production in hadronic collisions is presented. We consider the case of real photons in the final state, but include full leptonic decays of the $W$. Numerical results for the LHC and the Tevatron are obtained through a parton level Monte Carlo based on the structure of the VBFNLO program, allowing an easy implementation of general cuts and distributions. We show the dependence on scale variations of the integrated cross sections and provide evidence of the fact that next-to-leading-order QCD corrections strongly modify the leading order predictions for observables at the LHC both in magnitude and in shape.

We study at a quantitative level the impact of the uncertainties on the value of the $W$ boson mass measured at hadron colliders due to: i) the proton parton distribution functions (PDFs), ii) the value of the strong coupling constant ${\alpha }_s$ and iii) the value of the charm mass used in the PDF determination. The value of the $W$ boson mass is extracted, by means of a template fit technique, from the lepton-pair transverse mass distribution measured in the charged current Drell-Yan process. We study the determination of $m_W$ at the Tevatron and at the LHC with 7 and 14 TeV of center-of-mass energy in a realistic experimental setup. The analysis has been done at the Born level using the event generator HORACE and at NLO-QCD using the event generators DYNNLO and ResBos. We consider the three global PDF sets, CTEQ6.6, MSTW2008, and NNPDF2.1. We estimate that the total PDF uncertainty on $m_W$ is below 10 MeV both at the Tevatron and at the LHC for all energies and final states. We conclude that PDF uncertainties do not challenge a measurement of the $W$ boson mass at the level of 10 MeV accuracy.