There is a worldwide effort toward the development of a large time projection chamber devoted to directional dark matter detection. All current projects are being designed to fulfill a unique goal: identifying weakly interacting massive particle (WIMP) as such by taking advantage of the expected direction dependence of WIMP-induced events toward the constellation Cygnus. However, such proof of discovery requires a careful statistical data treatment. In this paper, the discovery potential of forthcoming directional detectors is addressed by using a frequentist approach based on the profile likelihood ratio test statistic. This allows us to estimate the expected significance of a dark matter detection taking into account astrophysical and experimental uncertainties. We show that the energy threshold and the background contamination are key experimental issues for directional detection, while angular resolution and sense recognition efficiency only mildly affect the sensitivity and the energy resolution is unimportant. This way, we found that a 30 kg.year ${\mathrm{CF}}_4$ directional experiment could reach a $3\sigma$ sensitivity at 90% C.L. down to ${10}^{-5}\mathrm{pb}$ and ${3.10}^{-4}\mathrm{pb}$ for the WIMP-proton axial cross section in the most optimistic and pessimistic detector performance case, respectively.

In this work, we study the light stop pair signals at the LHC. We explore the supersymmetry parameter space with nonuniversal gaugino and third-generation masses at the grand unified theory scale. Recent LHC supersymmetry search results based on $35{\mathrm{pb}}^{-1}$ and $1{\mathrm{fb}}^{-1}$ of data are implemented to put the limits on stop pair events. The dark matter relic density and direct detection constraints are also taken into account. Detailed simulations on the signals and background for some benchmark points are performed, and it is found that the stop pair signals usually escape the LHC search if the present cut conditions are used. We also explore the potential and sensitivity of ILC to probe such scenarios. It is found that the ILC can detect them with an integrated luminosity of a few tens of ${\mathrm{fb}}^{-1}$.

Dynamics of hadro-quarkonium system is formulated, based on the channel coupling of a light hadron $(h)$ and heavy quarkonium $(Q\overline{Q})$ to intermediate open-flavor heavy-light mesons ($Q\overline{q}$, $\overline{Q}q$). The resulting effective interaction is defined by overlap integrals of meson wave functions and $(hq\overline{q})$ coupling, where $h$ is $\pi$, $\rho$, $\omega$, $\varphi$, without fitting parameters. Equations for hadro-quarkonium amplitudes and resonance positions are written explicitly, and numerically calculated for the special case of $\pi {\rm Y}(nS)$ ($n=1$, 2, 3). It is also shown that the recently observed by Belle two peaks $Z_b(10610)$ and $Z_b(10650)$ are in agreement with the proposed theory. It is demonstrated, that theory predicts peaks at the $B{B}^{*}$, $B^{*}{B}^{*}$ thresholds in all available $\pi {\rm Y}(nS)$ channels. Analytic nature of these peaks is investigated, and shown to be due to a common multichannel resonance poles close to the $B{B}^{*}$, $B^{*}{B}^{*}$ thresholds. The general mechanism of these hadro-quarkonium resonances does not assume any molecular or four-quark (tetraquark) dynamics.

Bounds on the Higgs mass from the Tevatron and LHC are determined using exclusive jet bins to maximize sensitivity. Scale variation in exclusive fixed-order predictions underestimates the perturbative uncertainty for these cross sections, due to cancellations between the perturbative corrections leading to large $K$ factors and those that induce logarithmic sensitivity to the jet-bin boundary. To account for this, we propose that scale variation in the fixed-order calculations should be used to determine theory uncertainties for inclusive jet cross sections, whose differences yield exclusive jet cross sections. This yields a theory correlation matrix for the jet bins such that the additional uncertainty from large logarithms due to the jet boundary cancels when neighboring bins are added. This procedure is tested for $H+0,1$ jets, $WW+0$ jets, and $W+0,1,2$ jets, and found to be generally applicable. For a case where the higher-order resummation of the jet boundary corrections is known, we show that this procedure yields fixed-order uncertainties which are theoretically consistent with those obtained in the resummed calculation.

We discuss a simple approach to measure the weak mixing angles ${\varphi }_s$ and ${\varphi }_d$ of the $B_s$ and $B_d$ systems in the presence of New Physics. We present a new expression that allows one to measure directly ${\varphi }_{d,s}^{\mathrm{NP}}$ if New Physics contributes significantly to the mixing only. We apply the method to specific penguin-mediated $B\to PP$, $B\to PV$ and $B\to VV$ modes. We provide a very stringent and simple bound on the direct $CP$ asymmetries of all these modes, the violation of which is a signal of New Physics in decay. Within the same theoretical framework, an updated prediction for the branching ratio of $B_s\to K^{0*}{\overline{K}}^{0*}$ is presented, which can be compared with a recent LHCb analysis.

In this article, we calculate the contribution of the higher-twist Feynman diagrams to the large-$p_T$ inclusive single pion production cross section in photon-photon collisions in case of the running coupling and frozen coupling approaches within holographic QCD. We compare the resummed higher-twist cross sections with the ones obtained in the framework of the frozen coupling approach and leading-twist cross section. Also, we show that in the context of the frozen coupling approach a higher-twist contribution to the photon-photon collisions cross section is normalized in terms of the pion electromagnetic form factor.

The improved standard model prediction for total top quark forward-backward asymmetry of 8.9% at the Tevatron has significantly reduced the long-term discrepancy between the theory value and the experimental observations. The seemingly “last” over-3 $\sigma$ anomaly is the CDF measurement of $A_{\mathrm{FB}}(M_{t\overline{t}}>450\mathrm{GeV})$ and it is not seen by the D0 Collaboration. In this paper, we take the CDF measurement to obtain the best-fit parameter space for various previously proposed models, including axigluon, $t$-channel neutral current, charged current, and diquark models, then study the predictions of the corresponding parameter space on the direct search or indirect constrain. The particular axigluon model is excluded by the LHC dijet search. The $t$-channel $Z^{\prime }$ model suffer from the Tevatron same-sign dilepton search bound. The $t$-channel $W^{\prime }$ model and the diquark model both predict significant increase in the production rate of inclusive $t\overline{t}$ search at the LHC which is not seen. We conclude none of the models are favored by the direct search bound.

In this paper, we introduce a new approach to study jet substructure in the center-of-mass frame of the jet. We demonstrate that it can be used to discriminate the boosted heavy particles from the QCD jets and the method is complementary to other jet substructure algorithms. Applications to searches for hadronically decaying $W/Z+\mathrm{jets}$ and heavy resonances that decay to a $WW$ final state are also discussed.

Measurements of the normalized rapidity ($y$) and transverse-momentum ($q_{\mathrm{T}}$) distributions of Drell–Yan muon and electron pairs in the $Z$-boson mass region ($60<M_{\ell \ell }<120\mathrm{GeV}$) are reported. The results are obtained using a data sample of proton-proton collisions at a center-of-mass energy of 7 TeV, collected by the CMS experiment at the Large Hadron Collider (LHC), corresponding to an integrated luminosity of $36{\mathrm{pb}}^{-1}$. The distributions are measured over the ranges $|y|<3.5$ and $q_{\mathrm{T}}<600\mathrm{GeV}$ and compared with quantum chromodynamics (QCD) calculations using recent parton distribution functions to model the momenta of the quarks and gluons in the protons. Overall agreement is observed between the models and data for the rapidity distribution, while no single model describes the $Z$ transverse-momentum distribution over the full range.

We present a new determination of the $B_s$ leptonic decay constant from lattice QCD simulations that use gluon configurations from MILC and a highly improved discretization of the relativistic quark action for both valence quarks. Our result, $f_{B_s}=0.225(4)\mathrm{GeV}$, is almost 3 times more accurate than previous determinations. We analyze the dependence of the decay constant on the heavy quark’s mass and obtain the first empirical evidence for the leading $1/\sqrt{m_h}$ dependence predicted by heavy quark effective theory. As a check, we use our analysis technique to calculate the $m_{B_s}-m_{{\eta }_b}/2$ mass difference. Our result agrees with experiment to within errors of 11 MeV (better than 2%). We discuss how to extend our analysis to other quantities in $B_s$ and $B$ physics, making 2% precision possible for the first time.

Using a framework in which all elements are constrained by Dyson-Schwinger equation studies in QCD, and therefore incorporate a consistent, direct and simultaneous description of light- and heavy-quarks and the states they constitute, we analyze the accuracy of $SU(4)$-flavor symmetry relations between $\pi \rho \pi$, $K\rho K$, and $D\rho D$ couplings. Such relations are widely used in phenomenological analyses of the interactions between matter and charmed mesons. We find that while $SU(3)$-flavor symmetry is accurate to 20%, $SU(4)$ relations underestimate the $D\rho D$ coupling by a factor of 5.

Recently, it has been shown that one of the basic parameters of the neutrino sector, the so-called ${\theta }_{13}$ angle is very small but quite probably nonzero. We argue that the small value of ${\theta }_{13}$ can still be reproduced easily by a wide spectrum of randomly generated models of neutrino masses. For that we consider real and complex neutrino mass matrices, also including sterile neutrinos. A qualitative difference between results for real and complex mass matrices in the region of small ${\theta }_{13}$ values is observed. We show that statistically the present experimental data prefers random models of neutrino masses with sterile neutrinos.

We argue that the many worlds of quantum mechanics and the many worlds of the multiverse are the same thing, and that the multiverse is necessary to give exact operational meaning to probabilistic predictions from quantum mechanics. Decoherence—the modern version of wave-function collapse—is subjective in that it depends on the choice of a set of unmonitored degrees of freedom, the environment. In fact decoherence is absent in the complete description of any region larger than the future light cone of a measurement event. However, if one restricts to the causal diamond—the largest region that can be causally probed—then the boundary of the diamond acts as a one-way membrane and thus provides a preferred choice of environment. We argue that the global multiverse is a representation of the many worlds (all possible decoherent causal diamond histories) in a single geometry. We propose that it must be possible in principle to verify quantum-mechanical predictions exactly. This requires not only the existence of exact observables but two additional postulates: a single observer within the Universe can access infinitely many identical experiments; and the outcome of each experiment must be completely definite. In causal diamonds with a finite surface area, holographic entropy bounds imply that no exact observables exist, and both postulates fail: experiments cannot be repeated infinitely many times; and decoherence is not completely irreversible, so outcomes are not definite. We argue that our postulates can be satisfied in hats (supersymmetric multiverse regions with vanishing cosmological constant). We propose a complementarity principle that relates the approximate observables associated with finite causal diamonds to exact observables in the hat.

We present a formalism for the flavor oscillation of unstable particles that relies only upon the structure of the time Fourier-transformed two-point Green’s function. We derive exact oscillation probability and integrated oscillation probability formulae, and verify that our results reproduce the known results for both neutrino and neutral meson oscillation in the expected regimes of parameter space. The generality of our approach permits us to investigate flavor oscillation in exotic parameter regimes, and present the corresponding oscillation formulae.

In this work we present a theoretical framework that allows for the existence of coherent twinlike models in the context of self-dual Maxwell-Higgs theories. We verify the consistency of this framework by using it to develop some twinlike self-dual Maxwell-Higgs models. We use a combination of theoretical and numerical techniques to show that these models exhibit the very same topological Bogomol’nyi-Prasad-Sommerfield structures, including their field configurations and total energy. The study shows that it is possible to develop a completely consistent prescription, which extends the idea of twinlike models to the case of vortices in Maxwell-Higgs theories.

We consider two-dimensional $\mathcal{N}=(0,2)$ sigma models with the $CP(1)$ target space. A minimal model of this type has one left-handed fermion. Nonminimal extensions contain, in addition, $N_f$ right-handed fermions. Our task is to derive expressions for the $\beta$ functions valid to all orders. To this end we use a variety of methods: (i) perturbative analysis; (ii) instanton calculus; (iii) analysis of the supercurrent supermultiplet (the so-called hypercurrent) and its anomalies, and some other arguments. All these arguments, combined, indicate a direct parallel between the heterotic $\mathcal{N}=(0,2)$ $CP(1)$ models and four-dimensional super-Yang-Mills theories. In particular, the minimal $\mathcal{N}=(0,2)$ $CP(1)$ model is similar to $\mathcal{N}=1$ supersymmetric gluodynamics. Its exact $\beta$ function can be found; it has the structure of the Novikov-Shifman-Vainshtein-Zakharov (NSVZ) $\beta$ function of supersymmetric gluodynamics. The passage to nonminimal $\mathcal{N}=(0,2)$ sigma models is equivalent to adding matter. In this case an NSVZ-type exact relation between the $\beta$ function and the anomalous dimensions $\gamma$ of the “matter” fields is established. We derive an analog of the Konishi anomaly. At large $N_f$ our $\beta$ function develops an infrared fixed point at small values of the coupling constant (analogous to the Banks-Zaks fixed point). Thus, we reliably predict the existence of a conformal window. At $N_f=1$ the model under consideration reduces to the well-known $\mathcal{N}=(2,2)$ $CP(1)$ model.

When the phase structure of the black brane in a grand canonical ensemble is discussed, the bubble phase with the same boundary data should be included in this structure. As such, the phase transitions among bubbles, black branes, and “hot flat space” are possible, therefore giving a much enriched phase structure. We also argue that under some conditions, either the grand canonical ensemble itself is unstable or there are some unknown new phases.

The gravitational mass-shift effect is investigated in the framework of the standard model with the energy cutoff regularization both for stationary and nonstationary backgrounds at the one-loop level. The problem of singularity of the effective potential of the Higgs field on the horizon of a black hole, which was reported earlier, is resolved. The equations characterizing the properties of a vacuum state are derived and solved in a certain approximation for the Schwarzschild black hole. The gravitational mass-shift effect is completely described in this case. The behavior of masses of the massive particles of the standard model depends on the value of the Higgs boson mass in a flat spacetime. If the Higgs boson mass in a flat spacetime is less than 263.6 GeV then a mass of any massive particle approaching a gravitating object grows. If the Higgs boson mass in a flat spacetime is greater than or equal to 278.2 GeV, the masses of all the massive particles decrease in a strong gravitational field. The Higgs boson masses lying between these two values prove to lead to instability, at least at the one-loop level, and so they are excluded. It turns out that the vacuum possesses the same properties as an ultrarelativistic fluid in a certain approximation. The expression for the entropy and enthalpy densities and the pressure of this fluid are obtained. The sound speed in this fluid is also derived.

We discuss the properties of Lorentzian wormholes in dilatonic Einstein-Gauss-Bonnet theory in four spacetime dimensions. These wormholes do not need any form of exotic matter for their existence. A subset of these wormholes is shown to be linearly stable with respect to radial perturbations. We perform a comprehensive study of their domain of existence, and derive a generalized Smarr relation for these wormholes. We also investigate their geodesics, determining all possible particle trajectories, and perform a study of the acceleration and tidal forces that a traveler crossing the wormhole would feel.