We reconsider a model of two relativistic particles interacting via a multiplicative potential, as an example of a simple dynamical system with sectors, or branches, with different dynamics and degrees of freedom. The presence or absence of sectors depends on the values of rest masses. Some aspects of the canonical quantization are described. The model could be interpreted as a bigravity model in one dimension.

We explore here a new mechanism by which the out of equilibrium decay of heavy gravitinos, followed by possible R-parity violating decays in the minimal supersymmetric standard model (MSSM), can generate the baryon asymmetry of the Universe. In this mechanism, gravitino decay produces a $CP$ asymmetry that is carried by squarks or sleptons. These particles then decay through R-parity violating operators generating a lepton asymmetry. The lepton asymmetry is converted into a baryon asymmetry by weak sphalerons, as in the familiar case of leptogenesis by Majorana neutrino decays. To ensure that the gravitino decays while the sphaleron is still in equilibrium, we obtain a lower bound on the gravitino mass, $m_{3/2}\gtrsim {10}^8\mathrm{GeV}$, and therefore our mechanism requires a high scale of Supersymmetry (SUSY) breaking, as well as a minimum reheating temperature after inflation of $T\gtrsim {10}^{12}\mathrm{GeV}$ in order for the gravitino density to be sufficiently large to generate the baryon asymmetry today. We consider each of the MSSM’s relevant R-parity violating operators in turn, and we derive constraints on parameters in order to give rise to a baryon asymmetry comparable to that observed today, consistent with low energy phenomenological bounds on SUSY models. Interestingly, R-party violating terms that can produce a viable baryon asymmetry via the mechanism we explore can also radiatively produce neutrino masses corresponding to the observed magnitude, providing a new possible connection between neutrino mass generation and the origin of the baryon asymmetry today.

We propose a minimal model framework for physics below the Planck scale with the following features: (i) it is based on no-scale supergravity, as favored in many string compactifications, (ii) it incorporates Starobinsky-like inflation, and hence is compatible with constraints from the Planck satellite, (iii) the inflaton may be identified with a singlet field in a seesaw model for neutrino masses, providing an efficient scenario for reheating and leptogenesis, (iv) supersymmetry breaking occurs with an arbitrary scale and a cosmological constant that vanishes before radiative corrections, and (v) regions of the model parameter space are compatible with all LHC, Higgs boson, and dark matter constraints.

Considering that the effective theory of closed string tachyons can have world sheet supersymmetry, as shown by Vafa, we study a worldline supersymmetric action in a Friedmann–Robertson–Walker background, for which the superpotential originates a tachyon scalar potential. There are such potentials with spontaneously broken supersymmetry at the instability and supersymmetry after tachyon condensation. Furthermore, given a tachyonic potential, the superpotential can be computed by a power series ansatz and has a free parameter that can be chosen such that complex solutions become real.

We consider the dynamics of Dirac particles moving in the curved spaces with one coordinate subjected to compactification and thus interpolating smoothly between three- and two-dimensional spaces. We use the model of compactification, which allows us to perform the exact Foldy-Wouthuysen transformation of the Dirac equation and then to obtain the exact solutions of the equations of motion for momentum and spin in the classical limit. The spin precesses with the variable angular velocity, and a “flick” may appear in the remnant two-dimensional space once or twice during the period. We note an irreversibility in the particle dynamics because the particle can always penetrate from the lower-dimensional region to the higher-dimensional region, but not inversely.

We perform a high statistics calculation of disconnected fermion loops on graphics processing units for a range of nucleon matrix elements extracted using lattice QCD. The isoscalar electromagnetic and axial vector form factors, the sigma terms and the momentum fraction and helicity are among the quantities we evaluate. We compare the disconnected contributions to the connected ones and give the physical implications on nucleon observables that probe its structure.

We obtain limits on the quartic neutral gauge bosons couplings $Z\gamma \gamma \gamma$ and $ZZ\gamma \gamma$ using LEP 2 data published by the L3 Collaboration on the reactions $e^{+}{e}^{-}\to \gamma \gamma \gamma$, $Z\gamma \gamma$. We also obtain 95% C.L. limits on these couplings at the future linear colliders’ energies. The LEP 2 data induce limits of order $10^{-5}{\mathrm{GeV}}^{-4}$ for the $Z\gamma \gamma \gamma$ couplings and of order $10^{-3}{\mathrm{GeV}}^{-2}$ for the $ZZ\gamma \gamma$ couplings, which are still above the respective standard model predictions. Future $e^{+}{e}^{-}$ linear colliders may improve these limits by one or two orders of magnitude.

We present a general procedure for measuring the tensor structure of the coupling of the scalar Higgs-like boson recently discovered at the LHC to two $Z$ bosons, including the effects of interference among different operators. To motivate our concern with this interference, we explore the parameter space of the couplings in the effective theory describing these interactions and illustrate the effects of interference on the differential dilepton mass distributions. Kinematic discriminants for performing coupling measurements that utilize the effects of interference are developed and described. We present projections for the sensitivity of coupling measurements that use these discriminants in future LHC operation in a variety of physics scenarios.

In this paper we confront both the hadronic molecule and the hadro-charmonium interpretations of the $Y(4260)$ with the experimental data currently available. We conclude that the data support the $Y(4260)$ being dominantly a $D_1\overline{D}+\text{c.c.}$ hadronic molecule while they challenge the hadro-charmonium interpretation. However, additional data are necessary to allow for stronger conclusions.

In the case involving particles, the necessary and sufficient condition for the Penrose process to extract energy from a rotating black hole is absorption of particles with negative energies and angular momenta. No torque at the black-hole horizon occurs. In this article we consider the case of arbitrary fields or matter described by an unspecified, general energy-momentum tensor $T_{\mu \nu }$ and show that the necessary and sufficient condition for extraction of a black hole’s rotational energy is analogous to that in the mechanical Penrose process: absorption of negative energy and negative angular momentum. We also show that a necessary condition for the Penrose process to occur is for the Noether current (the conserved energy-momentum density vector) to be spacelike or past directed (timelike or null) on some part of the horizon. In the particle case, our general criterion for the occurrence of a Penrose process reproduces the standard result. In the case of relativistic jet-producing “magnetically arrested disks,” we show that the negative energy and angular-momentum absorption condition is obeyed when the Blandford-Znajek mechanism is at work, and hence the high energy extraction efficiency up to $\sim 300\%$ found in recent numerical simulations of such accretion flows results from tapping the black hole’s rotational energy through the Penrose process. We show how black-hole rotational energy extraction works in this case by describing the Penrose process in terms of the Noether current.

Renewed interest in GeV-scale sterile neutrinos capable of explaining active neutrino oscillations via a seesaw type I mechanism has been expressed in several proposals of direct searches. Given this activity we estimate the minimal values of sterile-active mixing angles provided one, two, or three sterile neutrinos are lighter than the $D$ meson.

In this paper, we study distorted, five-dimensional, electrically charged (nonextremal) black holes on the example of a static and “axisymmetric” black hole distorted by external, electrically neutral matter. Such a black hole is represented by the solution derived here of the Einstein-Maxwell equations which admits an ${\mathbb{R}}^1\times U(1)\times U(1)$ isometry group. The external matter, which is “located” at the asymptotic infinity, is not included in the solution. The space-time singularities are located behind the black hole’s inner (Cauchy) horizon, provided that the sources of the distortion satisfy the strong energy condition. The inner (Cauchy) horizon remains regular if the distortion fields are finite and smooth at the outer horizon. The solution has some remarkable properties. There exists a certain duality transformation between the inner and the outer horizon surfaces which links surface gravity, electrostatic potential, and space-time curvature invariants calculated at the black hole horizons. The product of the inner and outer horizon areas depends only on the black hole’s electric charge, and the geometric mean of the areas is the upper (lower) limit for the inner (outer) horizon area. The electromagnetic field invariant calculated at the horizons is proportional to the squared surface gravity of the horizons. The horizon areas, electrostatic potential, and surface gravity satisfy the Smarr formula. We formulated the zeroth and the first laws of mechanics and thermodynamics of the distorted black hole and found a correspondence between the global and local forms of the first law. To illustrate the effect of distortion, we consider the dipole-monopole and quadrupole-quadrupole distortion fields. The relative change in the Kretschmann scalar due to the distortion is greater at the outer horizon than at the inner one. By calculating the maximal proper time of free fall from the outer to the inner horizons, we show that the distortion can noticeably change the black hole interior. The change depends on the type and strength of distortion fields. In particular, due to the types of distortion fields considered here, the black hole horizons can either come arbitrarily close to or move far from each other.

It is shown how certain observations interpreted in the background of the Friedmann model with $\mathrm{\Lambda }<0=k$ (the $\mathrm{\Lambda }\mathrm{CDM}$ model) can be reinterpreted using the $\mathrm{\Lambda }=0$ Lemaître-Tolman (L-T) model so as to do away with the “dark energy.” The purpose of this paper is to clarify the underlying geometrical relations by doing the calculations as much as possible analytically or by very simple numerical programs. In the first part of the paper (fictitious) observations of the distribution of expansion velocity along the past light cone of the observer are considered. It is shown that the whole past light cone of the $\mathrm{\Lambda }\mathrm{CDM}$ observer can be reproduced in the L-T model with $\mathrm{\Lambda }=0=E$. This is a geometric exercise that has the advantage of being free of numerical complications. In the second part, the luminosity distance-redshift relation of the $\mathrm{\Lambda }\mathrm{CDM}$ model is duplicated using the L-T model with $-k=2E/r^2=\text{constant}>0$. The value of $k$ and the function $t_B(r)$ are determined by the $\mathrm{\Lambda }\mathrm{CDM}$ parameters. General properties of this L-T model are described. Difficulties of carrying the numerical calculations through the apparent horizon are presented in detail and mostly solved. The second model is a counterexample to the general belief that an L-T model mimicking $\mathrm{\Lambda }\mathrm{CDM}$ must contain a void around the center—it has a peak of density at $R=0$.

We present a relativistic quark model for the baryons that combines three related relativistic formalisms. The three-body constraint formalism of Sazdjian is used to recast three relativistic two-body equations for the three pairs of interacting quarks into a single relativistically covariant three-body equation for the bound state energies, having a Schrodinger-like structure. The two-body equations are the two-body Dirac equations of constraint dynamics derived by Crater and Van Alstine for combined world vector and scalar interactions providing the necessary spin dependent and spin independent interaction terms. The minimal quasipotential formalism of Todorov is used to provide an invariant framework for the vector and scalar dynamics used in the two-body Dirac equations into which is inserted a local simplified version of the Richardson potential. The spectral results are analyzed and compared to experiment using a best fit method and several different algorithms, including a gradient approach, and a Monte Carlo method.

We examine the impact of $D-\overline{D}$ mixing in the extraction of the angle $\gamma$ of the unitarity triangle with $B^{-}\to D^{(*)0}{K}^{(*)-}$ and $B^{-}\to D^{(*)0}{\pi }^{-}$ decays. We point out that the leading corrections, linear in the small mixing parameters $x=\mathrm{\Delta }m/\mathrm{\Gamma }$ and $y=\mathrm{\Delta }\mathrm{\Gamma }/2\mathrm{\Gamma }$, depend on how the signal selection efficiency varies as a function of the $D$ proper time, and we estimate the scale factor in a simplified case. We note that the charm mixing effect is suppressed in the Gronau-London-Wyler method. We discuss the case where the leading corrections become quadratic in $x$ and $y$, and we point out some limitations of this scenario. We compute the bias $\mathrm{\Delta }\gamma$ when $D-\overline{D}$ mixing is ignored in the rates of $B^{-}\to D^{(*)0}{K}^{(*)-}$ but not in the measurement of the $D$ decay parameters. We find $|\mathrm{\Delta }\gamma |\lesssim 1^{°}$ for all $B^{-}\to D^{(*)0}{K}^{(*)-}$ decays, limited by the measured value of the strong phase difference between the $b\to u\overline{c}s$ and $b\to c\overline{u}s$ decay amplitudes. On the other hand, we remark that the effect in $B^{-}\to D^{(*)0}{\pi }^{-}$ decays cannot be neglected.

We study the semileptonic $b\to u$ transition in the decay mode $B^{-}\to {\pi }^{+}{\pi }^{-}{\ell }^{-}{\overline{\nu }}_{\ell }$. We define $B\to \pi \pi$ form factors in the helicity basis, and study their properties in various kinematic limits, including form factor relations in the heavy-mass and large-energy limits, the decomposition into partial waves of the dipion system, and the resonant contribution of vector and scalar mesons. We show how angular observables in $B^{-}\to {\pi }^{+}{\pi }^{-}{\ell }^{-}{\overline{\nu }}_{\ell }$ can be used to measure dipion form factors or to perform null tests of the Standard Model.

We give a detailed description of the measurement of the $W$ boson mass, $M_W$, performed on an integrated luminosity of $4.3{\mathrm{fb}}^{-1}$, which is based on similar techniques as used for our previous measurement done on an independent data set of $1{\mathrm{fb}}^{-1}$ of data. The data were collected using the D0 detector at the Fermilab Tevatron Collider. This data set yields $1.68\times 10^6$ $W\to e\nu$ candidate events. We measure the mass using the transverse mass, electron transverse momentum, and missing transverse energy distributions. The $M_W$ measurements using the transverse mass and the electron transverse momentum distributions are the most precise of these three and are combined to give $M_W=80.367\pm 0.013(\text{stat})\pm 0.022(\text{syst})\mathrm{GeV}=80.367\pm 0.026\mathrm{GeV}$. When combined with our earlier measurement on $1{\mathrm{fb}}^{-1}$ of data, we obtain $M_W=80.375\pm 0.023\mathrm{GeV}$.

We study the gravitational clustering of spherically symmetric overdensities and the statistics of the resulting dark matter halos in the “symmetron model,” in which a new long range force is mediated by a $Z_2$ symmetric scalar field. Depending on the initial radius of the overdensity, we identify two distinct regimes: for small initial radii the symmetron mediated force affects the spherical collapse at all redshifts; for initial radii larger than some critical size this force vanishes before collapse because of the symmetron screening mechanism. As a consequence, halos with initial radii smaller than some critical value collapse earlier than in the $\mathrm{\Lambda }\mathrm{CDM}$ and statistically tend to form more massive dark matter halos. Regarding the halo mass function of these objects, we observe departures from standard $\mathrm{\Lambda }\mathrm{CDM}$ predictions at the few percent level. The formalism developed here can be easily applied to other models where fifth forces participate to the dynamics of the gravitational collapse.

The joint study of double-parton scattering (DPS) in high-energy proton-proton and proton-nucleus collisions can provide a lot of information on multiparton correlations. The multiparton structure is in fact probed in different ways by DPS in $p\text{−}p$ and in $p\text{−}A$ collisions. In $p\text{−}A$ collisions, the interpretation of the experimental results may be complicated, however, by the presence of interference terms, which are missing in $p\text{−}p$ collisions. A suitable reaction channel, where interference terms are absent, is $WJJ$ production. By studying $WJJ$ production in $p\text{−}Pb$ collisions, we estimate that the fraction of events due to DPS may be larger by a factor 3 or 4 as compared to $p\text{−}p$, while the amount of the increased fraction can give information on the importance of different correlation terms.

It has recently been pointed out that a component of the observed gamma-ray emission in the low latitudes of Fermi bubbles has a spectral shape that can be explained by a 10 GeV dark matter (DM) annihilating to tau leptons with a cross section of $2\times 10^{-27}{\mathrm{cm}}^3/\mathrm{s}$. Motivated by this possibility, we revisit the annihilation of a 10 GeV neutralino DM in the MSSM via stau exchange. The required stau masses and mixing, consistent with LEP direct search and electroweak precision constraints, are correlated with a possible enhancement of the Higgs decay rate to two photons. We also explore the implications of such a scenario for DM relic density and the muon anomalous magnetic moment, taking into account the recent ATLAS bounds on the chargino and the first two generation slepton masses, as well as the constraints on the Higgsino fraction of a 10 GeV neutralino.