We study the discovery potential of the flavor-changing neutral coupling (FCNC) $htc$ of the Higgs boson and the top quark through the rare tree-body decay $h\to Wbc$ at muon colliders for a light Higgs boson with mass $114\le m_h\le 145\mathrm{GeV}$. This decay mode may compete with the standard model (SM) background induced by the $hWW$ coupling in some models with a tree-level $htc$ coupling and with models that predict this coupling at the one-loop level in the range ${10}^{-2}-{10}^{-1}$. A future muon collider could test the scalar FCNC decay $t\to hc$ via Higgs decay $h\to t^{*}c\to b{W}^{+}c$ down to values of the coupling $g_{tc}=0.5$ [that are equivalent to $\mathrm{BR}(t\to hc)\sim 5\times {10}^{-3}$]. The LHC could probe values of $g_{tc}$ 1 order of magnitude smaller, unless other processes beyond the SM appear that through intense multijet activity may clutter the $t\to hc$ signal.

We study low energy constraints from flavor violating processes, production, and decay at the LHC of a scalar field $\phi$ (flavon) associated to the breaking of a nonsupersymmetric Abelian family symmetry at the TeV scale. This symmetry is constrained to reproduce fermion masses and mixing, up to $O(1)$ coefficients. The nonsupersymmetric gauged $U(1)$ models considered are severely restricted by cancellation of anomalies and LEP bounds on contact interactions; consequently its phenomenology is out of the LHC reach. We therefore introduce an effective $U(1)$ which is not gauged and is broken explicitly by a $CP$-odd term at the TeV scale. This helps us to explore flavor violating processes, production, and decay at the LHC for these kind of light scalars. In this context we first study the constraints on the flavon mass and its vacuum expectation value from low energy flavor changing processes such as $\mu \to e\gamma$. We find that a flavon of about $m_{\phi }\lesssim 150\mathrm{GeV}$ could be experimentally allowed. These kinds of flavons could be significantly generated at the LHC via the gluon fusion mechanism and the single top production channel $gu\to t\phi$. The produced flavons can have characteristic decay modes such as $t\overline{c}$ for $m_{\phi }\gtrsim m_t$, and $\tau \overline{\mu }$ for $m_{\phi }\lesssim m_t$, which could be effectively useful to detect flavons.

We discuss the correlated systematic theoretical uncertainties that may be ascribed to the next-to-leading order QCD theory used to predict the one-jet inclusive cross section in hadron collisions. We estimate the magnitude of these errors as functions of the jet transverse momentum and rapidity. The total theoretical error is decomposed into a set of functions of transverse momentum and rapidity that give a model for statistically independent contributions to the error. This representation can be used to include the systematic theoretical errors in fits to the experimental data.

A recent observation of the two candidate events of the dark matter recoiling at CDMS-II is suggestive of dark matter with a mass not far above 100 GeV. We propose a model of gauge mediated supersymmetry breaking where the lightest neutralino is identified as dark matter which may provide the observed signals.

We report evidence for the ground state of bottomonium, ${\eta }_b(1S)$, in the radiative decay ${\rm Y}(3S)\to \gamma {\eta }_b$ in $e^{+}{e}^{-}$ annihilation data taken with the CLEO III detector. Using $6\times {10}^6$ ${\rm Y}(3S)$ decays, and assuming $\Gamma ({\eta }_b)=10\pm 5\mathrm{MeV}/c^2$, we obtain $\mathcal{B}({\rm Y}(3S)\to \gamma {\eta }_b)=(7.1\pm 1.8\pm 1.3)\times {10}^{-4}$, where the first error is statistical and the second is systematic. The statistical significance is $\sim 4\sigma$. The mass is determined to be $M({\eta }_b)=9391.8\pm 6.6\pm 2.0\mathrm{MeV}/c^2$, which corresponds to the hyperfine splitting $\Delta M_{\mathrm{hf}}(1S{)}_b=68.5\pm 6.6\pm 2.0\mathrm{MeV}/c^2$. Using $9\times {10}^6$ ${\rm Y}(2S)$ decays, we place an upper limit on the corresponding ${\rm Y}(2S)$ decay, $\mathcal{B}({\rm Y}(2S)\to \gamma {\eta }_b)<8.4\times {10}^{-4}$ at 90% confidence level.

Jacobi’s action principle is known to lead to a problem of time. For example, the timelessness of the Wheeler-DeWitt equation can be seen as resulting from using Jacobi’s principle to define the dynamics of 3-geometries through superspace. In addition, using Jacobi’s principle for nonrelativistic particles is equivalent classically to Newton’s theory but leads to a time-independent Schrödinger equation upon Dirac quantization. In this paper, we study the mechanism for the disappearance of time as a result of using Jacobi’s principle in these simple particle models. We find that the path integral quantization very clearly elucidates the physical mechanism for the timeless of the quantum theory as well as the emergence of duration at the classical level. Physically, this is the result of a superposition of clocks, which occurs in the quantum theory due to a sum over all histories. Mathematically, the timelessness is related to how the gauge fixing functions impose the boundary conditions in the path integral.

Some functions entering cosmological analysis, such as the dark energy equation of state or systematic uncertainties, are unknown functions of redshift. To include them without assuming a particular form, we derive an efficient method for generating realizations of all possible functions subject to certain bounds or physical conditions, e.g. $w\in [-1,+1]$ as for quintessence. The method is optimal in the sense that it is both pure and complete in filling the allowed space of principal components. The technique is applied to propagation of systematic uncertainties in supernova population drift and dust corrections and calibration through to cosmology parameter estimation and bias in the magnitude-redshift Hubble diagram. We identify specific ranges of redshift and wavelength bands where the greatest improvements in supernova systematics due to population evolution and dust correction can be achieved.

In this paper we propose to interpret the large discretization artifacts affecting the neutral pion mass in maximally twisted lattice QCD simulations as O($a^2$) effects, whose magnitude is roughly proportional to the modulus square of the (continuum) matrix element of the pseudoscalar density operator between vacuum and one-pion state. The numerical size of this quantity is determined by the dynamical mechanism of spontaneous chiral symmetry breaking and turns out to be substantially larger than its natural magnitude set by the value of ${\Lambda }_{\mathrm{QCD}}$.

The fractured Boer-Mulders functions, ${\Delta }^N{M}_{B\uparrow /\{q,q\}\uparrow :p}^q(x,p_{TN};z,{\overrightarrow{p}}_T·{\overrightarrow{k}}_T;Q^2)$, describe an intriguing class of polarization effects for the production of baryons in the target fragmentation region of deep-inelastic processes. These functions characterize transverse momentum asymmetries related to the spin orientation for different flavors of axial-vector diquarks,$\{q_i,q_j\}\uparrow$, in an unpolarized ensemble of protons just as the familiar Boer-Mulders functions characterize transverse momentum asymmetries connected to the spin orientation of quarks in unpolarized targets. The asymmetries in $p_{TN}$ of the fractured Boer-Mulders effect originating in the proton distribution function can be separated kinematically, both in semi-inclusive deep-inelastic scattering and in the Drell-Yan process, from the asymmetries in $k_{TN}$ of the polarizing fracture functions, ${\Delta }^N{M}_{B\uparrow /(q,q):p}^q(x,p_T{}^2;z,k_{TN};Q^2)$, generated during the soft color rearrangement of the fragmentation process. The experimental requirements for this separation are presented in this article and it is shown that the fractured Boer-Mulders effect should change sign between Drell-Yan and semi-inclusive deep-inelastic scattering while the polarizing fracture functions remain the same. Simple isospin arguments indicate the two polarization mechanisms should give significantly different results for the production of polarized $\Lambda$’s and $\Sigma$’s.

We derive a simple formula for the stopping distance for a high-energy quark traveling through a weakly coupled quark-gluon plasma. The result is given to next-to-leading order in an expansion in inverse logarithms $\ln (E/T)$, where $T$ is the temperature of the plasma. We also define a stopping distance for gluons and give a leading-log result. Discussion of stopping distance has a theoretical advantage over discussion of energy loss rates in that stopping distances can be generalized to the case of strong coupling, where one may not speak of individual partons.

We study the effects of substructure on the rate of dark-matter annihilation in the Galactic halo. We use an analytic model for substructure that can extend numerical simulation results to scales too small to be resolved by the simulations. We first calibrate the analytic model to numerical simulations, and then determine the annihilation boost factor, for standard weakly interacting massive particle (WIMP) models as well as those with Sommerfeld (or other) enhancements, as a function of galactocentric radius in the Milky Way. We provide an estimate of the dependence of the gamma-ray intensity of WIMP annihilation as a function of angular distance from the Galactic center. This methodology, coupled with future numerical simulation results can be a powerful tool that can be used to constrain WIMP properties using Fermi all-sky data.

The cross sections of $e^{+}{e}^{-}$ to $S$-wave and $P$-wave quarkonia with $C$-parity even associated with a photon are analyzed in the framework of nonrelativistic Quantum Chromodynamics (NRQCD) factorization formulism. The short-distance coefficients are analytically determined up to the next-to-leading order (NLO) QCD radiative corrections to $S$-wave and $P$-wave quarkonium production and NLO relativistic correction to ${\eta }_c$ production. We also invoke the analytical expressions to estimate the cross sections. Our numerical results indicate that both the QCD and the relativistic corrections are considerable.

We first obtain the most general and compact parametrization of the unitary transformation diagonalizing any $3\times 3$ Hermitian matrix $H$, as a function of its elements and eigenvalues. We then study a special class of fermion mass matrices, defined by the requirement that all of the diagonalizing unitary matrices (in the up, down, charged lepton, and neutrino sectors) contain at least one mixing angle much smaller than the other two. Our new parametrization allows us to quickly extract information on the patterns and predictions emerging from this scheme. In particular we find that the phase difference between two elements of the two mass matrices (of the sector in question) controls the generic size of one of the observable fermion mixing angles: i.e. just fixing that particular phase difference will predict the generic value of one of the mixing angles, irrespective of the value of anything else.

We present a study of $B\to X(3872)K$ with $X(3872)$ decaying to $D^{*0}{\overline{D}}^0$ using a sample of $657\times {10}^6$ $B\overline{B}$ pairs recorded at the ${\rm Y}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. Both $D^{*0}\to D^0\gamma$ and $D^{*0}\to D^0{\pi }^0$ decay modes are used. We find a peak of ${50.1}_{-11.1}^{+14.8}$ events with a mass of $({3872.9}_{-0.4-0.5}^{+0.6+0.4})\mathrm{MeV}/c^2$, a width of $({3.9}_{-1.4-1.1}^{+2.8+0.2})\mathrm{MeV}/c^2$ and a product branching fraction $\mathcal{B}(B\to X(3872)K)\times \mathcal{B}(X(3872)\to D^{*0}{\overline{D}}^0)=(0.80\pm 0.20\pm 0.10)\times {10}^{-4}$, where the first errors are statistical and the second ones are systematic. The significance of the signal is $6.4\sigma$. The difference between the fitted mass and the $D^{*0}{\overline{D}}^0$ threshold is calculated to be $({1.1}_{-0.4-0.3}^{+0.6+0.1})\mathrm{MeV}/c^2$. We also obtain an upper limit on the product of branching fractions $\mathcal{B}(B\to Y(3940)K)\times \mathcal{B}(Y(3940)\to D^{*0}{\overline{D}}^0)$ of $0.67\times {10}^{-4}$ at 90% CL.

We compute a shift of baryon mass spectra due to quark masses in perturbation, in the Sakai-Sugimoto model of holographic QCD. We find the shift for the ground state nucleons to be $\delta M=4.1m_{\pi }^2{\mathrm{GeV}}^{-1}$, which is consistent with the current lattice QCD result. We predict the same value of the shift for $N(1535)$, while a larger value $7.7m_{\pi }^2{\mathrm{GeV}}^{-1}$ for Roper $N(1440)$. We also present some evidences that the shifts of the vector meson masses are suppressed in the large ’t Hooft coupling limit.

We study the relation between the thermodynamics and field equations of generalized gravity theories on the dynamical trapping horizon with sphere symmetry. We assume the entropy of a dynamical horizon as the Noether charge associated with the Kodama vector and point out that it satisfies the second law when a Gibbs equation holds. We generalize two kinds of Gibbs equations to Gauss-Bonnet gravity on any trapping horizon. Based on the quasilocal gravitational energy found recently for $f(R)$ gravity and scalar-tensor gravity in some special cases, we also build up the Gibbs equations, where the nonequilibrium entropy production, which is usually invoked to balance the energy conservation, is just absorbed into the modified Wald entropy in the Friedmann-Robertson-Walker spacetime with slowly varying horizon. Moreover, the equilibrium thermodynamic identity remains valid for $f(R)$ gravity in a static spacetime. Our work provides an alternative treatment to reinterpret the nonequilibrium correction and supports the idea that the horizon thermodynamics is universal for generalized gravity theories.

The action principle of the BF type introduced by Capovilla, Montesinos, Prieto, and Rojas (CMPR) which describes general relativity with Immirzi parameter is modified in order to allow the inclusion of the cosmological constant. The resulting action principle is on the same footing as the original Plebanski action in the sense that the equations of motion coming from the new action principle are equivalent to the Holst action principle plus a cosmological constant without the need of imposing additional restrictions on the fields. We consider this result a relevant step towards the coupling of matter fields to gravity in the framework of the CMPR action principle.

The properties of static, spherically symmetric configurations are considered in the framework of two models of nonlocally corrected gravity, suggested in S. Deser and R. Woodard, Phys. Rev. Lett. 99, 111301 (2007) and S. Capozziello et al., Phys. Lett. B 671, 193 (2009). For the first case, where the Lagrangian of nonlocal origin represents a scalar-tensor theory with two massless scalars, an explicit condition is found under which both scalar fields are canonical (nonphantom). If this condition does not hold, one of the fields exhibits a phantom behavior. Scalar-vacuum configurations then behave in a manner known for scalar-tensor theories. In the second case, the Lagrangian of nonlocal origin exhibits a scalar field interacting with the Gauss-Bonnet (GB) invariant and contains an arbitrary scalar field potential. It is found that the GB term, in general, leads to violation of the well-known no-go theorems valid for minimally coupled scalar fields in general relativity. It is shown, however, that some configurations of interest are still forbidden—whatever be the scalar field potential and the GB-scalar coupling function, namely, “force-free” wormholes (such that $g_{tt}=\mathrm{const}$) and black holes with higher-order horizons.