Samples of inclusive $\gamma +2$ jet and $\gamma +3$ jet events collected by the D0 experiment with an integrated luminosity of about $1{\mathrm{fb}}^{-1}$ in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ are used to measure cross sections as a function of the angle in the plane transverse to the beam direction between the transverse momentum ($p_T$) of the $\gamma +\mathrm{\text{leading jet system}}$ (jets are ordered in $p_T$) and $p_T$ of the other jet for $\gamma +2$ jet, or $p_T$ sum of the two other jets for $\gamma +3$ jet events. The results are compared to different models of multiple parton interactions (MPI) in the pythia and sherpa Monte Carlo (MC) generators. The data indicate a contribution from events with double parton (DP) interactions and are well-described by predictions provided by the pythia MPI models with $p_T$-ordered showers and by sherpa with the default MPI model. The $\gamma +2$ jet data are also used to determine the fraction of events with DP interactions as a function of the azimuthal angle and as a function of the second jet $p_T$.

Using a high-statistics, high-purity sample of ${\nu }_{\mu }$-induced charged current, charged pion events in mineral oil (${\mathrm{CH}}_2$), MiniBooNE reports a collection of interaction cross sections for this process. This includes measurements of the $\mathrm{CC}{\pi }^{+}$ cross section as a function of neutrino energy, as well as flux-averaged single- and double-differential cross sections of the energy and direction of both the final-state muon and pion. In addition, each of the single-differential cross sections are extracted as a function of neutrino energy to decouple the shape of the MiniBooNE energy spectrum from the results. In many cases, these cross sections are the first time such quantities have been measured on a nuclear target and in the 1 GeV energy range.

We investigate the phase transitions of holographic $p$-wave superconductors in ($4+1$)-dimensional Einstein-Yang-Mills-Gauss-Bonnet theories, in a grand canonical ensemble. Turning on the backreaction of the Yang-Mills field, it is found that the condensations of vector order parameter become harder if the Gauss-Bonnet coefficient grows up or the backreaction becomes stronger. In particular, the vector order parameter exhibits the features of first order and second order phase transitions, while only the second order phase transition is observed in the probe limit. We discuss the roles that the Gauss-Bonnet term and the backreaction play in changing the order of phase transition.

We classify all possible implementations of an Abelian symmetry in the two-Higgs-doublet model with fermions. We identify those symmetries which are consistent with nonvanishing quark masses and a Cabibbo-Kobayashi-Maskawa quark-mixing matrix (CKM), which is not block-diagonal. Our analysis takes us from a plethora of possibilities down to 246 relevant cases, requiring only 34 distinct matrix forms. We show that applying $Z_n$ with $n\ge 4$ to the scalar sector leads to a continuous $U(1)$ symmetry in the whole Lagrangian. Finally, we address the possibilities of spontaneous $CP$ violation and of natural suppression of the flavor-changing neutral currents. We explain why our work is relevant even for non-Abelian symmetries.

If there are scalar particles of small or moderate mass coupled very weakly to Dirac neutrinos, in a minimal way, then neutrino-anti-neutrino clouds of sufficient number density can experience an instability in which helicities are suddenly reversed. The predicted collective evolution is many orders of magnitude faster than given by cross section calculations. The instabilities are the analogue of the “flavor-angle” instabilities (enabled by the $Z$ exchange force) that may drive very rapid flavor exchange among the neutrinos that emerge from a supernova. These exchanges do require a tiny seed in addition to the scalar couplings, but the transition time is proportional to the negative of the logarithm of the seed strength, so that the size of this parameter is comparatively unimportant. For our actual estimates we use a tiny nonconservation of leptons; an alternative would be a neutrino magnetic moment in a small magnetic field. The possibility of a quantum fluctuation as a seed is also discussed. Operating in the mode of putting limits on the coupling constant of the scalar field, for the most minimal coupling scheme, with independent couplings to all three $\nu$, we find a rough limit on the dimensionless coupling constant for a neutrino-flavor independent coupling of $G<{10}^{-10}$, to avoid the effective number of light neutrinos in the early universe being essentially six. If, on the other hand, we wish to fine-tune the model to give a more modest excess (over three) in the effective neutrino number, as may be needed according to recent WMAP analyses, it is easy to do so.

We construct the magnetic dual of QCD with one adjoint Weyl fermion. The dual is a consistent solution of the ’t Hooft anomaly matching conditions, allows for flavor decoupling, and remarkably constitutes the first nonsupersymmetric dual valid for any number of colors. The dual allows to bound the anomalous dimension of the Dirac fermion mass operator to be less than one in the conformal window.

We studied the rate at which stars capture dark matter (DM) particles, considering different assumptions regarding the DM characteristics and, in particular, investigating how the stellar physics influences the capture rate. Two scenarios were considered: first, we assumed the maximal values for the spin-dependent and spin-independent DM particle-nucleon scattering cross sections allowed by the limits from direct detection experiments. Second, we considered that both scattering cross sections are of the same order, with the aim of studying the dependencies of the capture rate on stellar elements other than hydrogen. We found that the characteristics of the capture rate are very different in the two scenarios. Furthermore, we quantified the uncertainties on the computed capture rate ($C_{\chi }$) and on the ratio between the luminosities from DM annihilations and thermonuclear reactions ($L_{\chi }/L_{\mathrm{nuc}}$) derived from an imprecise knowledge of the stellar structure and DM parameters. For instance, while an uncertainty of 10% on the typical DM velocity leads to similar errors on the computed $C_{\chi }$ and $L_{\chi }/L_{\mathrm{nuc}}$, the same uncertainty on the stellar mass becomes more relevant and duplicates the errors. Our results may be used to evaluate the reliability of the computed capture rate for the hypothetical use of stars other than the Sun as DM probes.

As very high energy ($\gtrsim 100\mathrm{GeV}$) gamma rays travel over cosmological distances, their flux is attenuated through interactions with the extragalactic background light. Observations of distant gamma ray sources at energies between $\sim 200\mathrm{GeV}$ and a few TeV by ground-based gamma-ray telescopes such as HESS, however, have motivated the possibility that the universe is more transparent to very high energy photons than had been anticipated. One proposed explanation for this is the existence of axionlike particles (ALPs) which gamma rays can efficiently oscillate into, enabling them to travel cosmological distances without attenuation. In this article, we use a state-of-the-art model for the extragalactic background light (which is somewhat lower at $\sim \mu \mathrm{m}$ wavelengths than in previous models) and data from the Fermi Gamma Ray Space Telescope to calculate the spectra at 1–100 GeV of two gamma-ray sources, 1ES1101-232 at redshift $z=0.186$ and H2356-309 at $z=0.165$, in conjunction with the measurements of ground-based telescopes, to test the ALP hypothesis. We find that these observations can be well fit by an intrinsic power-law source spectrum with indices of $-1.72$ and $-2.1$ for 1ES1101-232 and H2356-309, respectively, and that no ALPs or other exotic physics is necessary to explain the observed degree of attenuation. While this does not exclude the possibility that ALPs are involved in the cosmological propagation of gamma rays, it does reduce the motivation for such new physics.

With the augmentation of IceCube by DeepCore, the prospect for detecting dark matter annihilation in the Sun is much improved. To complement this experimental development, we provide a thorough template analysis of the particle physics issues that are necessary to precisely interpret the data. Our study is about nitty-gritty and is intended as a framework for detailed work on a variety of dark matter candidates. To accurately predict the source neutrino spectrum, we account for spin-correlations of the final state particles and the helicity-dependence of their decays, and absorption effects at production. We fully treat the propagation of neutrinos through the Sun, including neutrino oscillations, energy losses and tau regeneration. We simulate the survival probability of muons produced in the Earth by using the Muon Monte Carlo program, reproduce the published IceCube effective area, and update the parameters in the differential equation that approximates muon energy losses. To evaluate the zenith-angle dependent atmospheric background event rate, we track the Sun and determine the time it spends at each zenith-angle. Throughout, we employ neutralino dark matter as our example.

We present the results of extensive simulations regarding the critical behavior at the endpoint of the Roberge-Weiss transition for $N_f=2$ QCD. We confirm early evidence, presented in Ref. [M. D’Elia and F. Sanfilippo, Phys. Rev. D 80, 111501(R) (2009).], according to which the Roberge-Weiss endpoint is first order in the limit of large or small quark masses, and second order for intermediate masses. A systematic study of the transition strength as a function of the quark mass in the first order regions, permits us to estimate the tricritical values of the quark mass separating the second order region from the first order ones.

Studies of the nature of cosmic ray particles at the highest energies are based on the measurement of extensive air showers. Most cosmic ray properties can therefore be obtained only from the interpretation of air shower data and are thus dependent on predictions of hadronic interaction models at ultrahigh energies. We discuss different scenarios of model extrapolations from accelerator data to air shower energies and investigate their impact on the corresponding air shower predictions. To explore the effect of different extrapolations by hadronic interaction models we developed an ad hoc model. This model is based on the modification of the output of standard hadronic interaction event generators within the air shower simulation process and allows us to study the impact of changing interaction features on the air shower development. In a systematic study we demonstrate the resulting changes of important air shower observables and also discuss them in terms of the predictions of the Heitler model of air shower cascades. It is found that the results of our ad hoc modifications are, to a large extent, independent of the choice of the underlying hadronic interaction model.

We present the measurement of nonphotonic electron production at high transverse momentum ($p_T>2.5\mathrm{GeV}/c$) in $p+p$ collisions at $\sqrt{s}=200\mathrm{GeV}$ using data recorded during 2005 and 2008 by the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The measured cross sections from the two runs are consistent with each other despite a large difference in photonic background levels due to different detector configurations. We compare the measured nonphotonic electron cross sections with previously published RHIC data and perturbative quantum chromodynamics calculations. Using the relative contributions of B and D mesons to nonphotonic electrons, we determine the integrated cross sections of electrons ($\frac{e^{+}+e^{-}}{2}$) at $3\mathrm{GeV}/c<p_T<10\mathrm{GeV}/c$ from bottom and charm meson decays to be $[(d{\sigma }_{(B\to e)+(B\to D\to e)})/(d{y}_e){]}_{y_e=0}=4.0\pm 0.5(\mathrm{stat})\pm 1.1(\mathrm{syst})\mathrm{nb}$ and $[(d{\sigma }_{D\to e})/(d{y}_e){]}_{y_e=0}=6.2\pm 0.7(\mathrm{stat})\pm 1.5(\mathrm{syst})\mathrm{nb}$, respectively.

We present a formalism that allows the computation of the baryon asymmetry of the Universe, from the first principles of statistical physics and quantum field theory, that is applicable to certain types of physics beyond the standard model (such as the neutrino minimal standard model) and does not require the solution of Boltzmann or Kadanoff-Baym equations. The formalism works if a thermal bath of standard model particles is very weakly coupled to a new sector (sterile neutrinos in the neutrino minimal standard model case) that is out-of-equilibrium. The key point that allows a computation without kinetic equations is that the number of sterile neutrinos produced during the relevant cosmological period remains small. In such a case, it is possible to expand the formal solution of the von Neumann equation perturbatively and obtain a master formula for the lepton asymmetry expressed in terms of nonequilibrium Wightman functions. The master formula neatly separates $CP$-violating contributions from finite temperature correlation functions and satisfies all three Sakharov conditions. These correlation functions can then be evaluated perturbatively; the validity of the perturbative expansion depends on the parameters of the model considered. Here, we choose a toy model (containing only two active and two sterile neutrinos) to illustrate the use of the formalism, but it could be applied to other models.

Perturbations of Schwarzschild-Droste black holes in the Regge-Wheeler gauge benefit from the availability of a wave equation and from the gauge invariance of the wave function, but lack smoothness. Nevertheless, the even perturbations belong to the $C^0$ continuity class, if the wave function and its derivatives satisfy specific conditions on the discontinuities, known as jump conditions, at the particle position. These conditions suggest a new way for dealing with finite element integration in the time domain. The forward time value in the upper node of the $(t,r^{*})$ grid cell is obtained by the linear combination of the three preceding node values and of analytic expressions based on the jump conditions. The numerical integration does not deal directly with the source term, the associated singularities and the potential. This amounts to an indirect integration of the wave equation. The known wave forms at infinity are recovered and the wave function at the particle position is shown. In this series of papers, the radial trajectory is dealt with first, being this method of integration applicable to generic orbits of EMRI (Extreme Mass Ratio Inspiral).

We show how recent data from observations of the cosmic microwave background may suggest the presence of additional radiation density which appeared after big bang nucleosynthesis. We propose a general scheme by which this radiation could be produced from the decay of nonrelativistic matter, we place constraints on the properties of such matter, and we give specific examples of scenarios in which this general scheme may be realized.

The standard model of cosmology $\Lambda \mathrm{CDM}$ assumes general relativity, flat space, and the presence of a positive cosmological constant. We relax these assumptions allowing spatial curvature, a time-dependent effective dark energy equation of state, as well as modifications of the Poisson equation for the lensing potential, and modifications of the growth of linear matter density perturbations in alternate combinations. Using six parameters characterizing these relations, we check $\Lambda \mathrm{CDM}$ for consistency utilizing cosmic microwave background anisotropies, cross correlations thereof with high-redshift galaxies through the integrated Sachs-Wolfe effect, the Hubble constant, supernovae, and baryon acoustic oscillation distances, as well as the relation between weak gravitational lensing and galaxy flows. In all scenarios, we find consistency of the concordance model at the 95% confidence level. However, we emphasize that constraining supplementary background parameters and parametrizations of the growth of large-scale structure separately may lead to a priori exclusion of viable departures from the concordance model.

A special class of the Bianchi type VI expanding solutions was speculated to break the cosmic no-hair theorem that will not approach the late-time de Sitter solution. We will show that an unstable mode always exists when the perturbation of the field equations is applied to the system. In addition to a model-independent perturbation formula, a simplification is also achieved by the introduction of a $\delta R=0$ solution good for quadratic models in all Bianchi spaces. The result shows that this special class of anisotropically expanding solutions is unstable.

The sign problem is a notorious problem, which occurs in Monte Carlo simulations of a system with the partition function whose integrand is not real positive. The basic idea of the factorization method applied on such a system is to control some observables in order to determine and sample efficiently the region of configuration space which gives important contribution to the partition function. We argue that it is crucial to choose appropriately the set of the observables to be controlled in order for the method to work successfully in a general system. This is demonstrated by an explicit example, in which it turns out to be necessary to control more than one observable. Extrapolation to large system size is possible due to the nice scaling properties of the factorized functions, and known results obtained by an analytic method are shown to be consistently reproduced.

We derive relations between transverse momentum dependent distribution functions and the usual parton distribution functions in the 3D covariant parton model, which follow from Lorentz invariance and the assumption of a rotationally symmetric distribution of parton momenta in the nucleon rest frame. Using the known parton distribution functions $f_1^a(x)$ and $g_1^a(x)$ as input we predict the $x$- and ${\mathbf{p}}_T$-dependence of all twist-2 T-even transverse momentum dependent distribution functions.