Thermal unparticles: a new form of energy density in the universe

An unparticle with scaling dimension has peculiar thermal properties due to its unique phase space structure. We find that the equation of state parameter , the ratio of pressure to energy density, is given by providing a new form of energy in our universe. In an expanding universe, the unparticle energy density evolves dramatically differently from that for photons. For , even if at a high decoupling temperature T _D is very small, it is possible to have a large relic density at present photon temperature T _γ ⁰, large enough to play the role of dark matter. We calculate T _D and using photon–unparticle interactions for illustration.     

FANSY 1.0: a phenomenological model for simulation of coplanar particle generation in superhigh-energy hadron interactions

Simulations show that a phenomenon of coplanarity of most energetic subcores of γ-ray–hadron families found in mountain-based and stratospheric X-ray–emulsion chamber experiments requires to introduce a coplanar particle generation with large transverse momenta in hadron interactions at superhigh energies. Some physical mechanisms are considered. A phenomenological model, which makes it possible to simulate the coplanar particle generation, is presented. Different versions of this model are considered, their features are described and compared with those of models applied by the CORSIKA package. Cosmic-ray experimental data and simulated results are compared. Conclusion on features of hadron interactions at superhigh energies and some predictions with respect to LHC experiments are made.     

From Euclidean to Minkowski space with the Cauchy–Riemann equations

We present an elementary method to obtain Green’s functions in non-perturbative quantum field theory in Minkowski space from Green’s functions calculated in Euclidean space. Since in non-perturbative field theory the analytical structure of amplitudes often is unknown, especially in the presence of confined fields, dispersive representations suffer from systematic uncertainties. Therefore, we suggest to use the Cauchy–Riemann equations, which perform the analytical continuation without assuming global information on the function in the entire complex plane, but only in the region through which the equations are solved. We use as example the quark propagator in Landau gauge quantum chromodynamics, which is known from lattice and Dyson–Schwinger studies in Euclidean space. The drawback of the method is the instability of the Cauchy–Riemann equations against high-frequency noise,which makes it difficult to achieve good accuracy. We also point out a few curious details related to the Wick rotation.     

Effect of top quark spin on the unparticle couplings in $\gamma\gamma \to t\bar{t}$

We investigate the potential of γ γ collisions to probe scalar unparticle couplings via top–antitop quark pair production. We find 95% confidence level limits on the unparticle couplings with an integrated luminosity of 500 fb⁻¹ and an energy of  TeV. We investigate the effect of the top quark spin polarization on the unparticle couplings. It is shown that spin polarization of the top quark leads to a significant improvement in the sensitivity limits.     

A QCD motivated model for soft interactions at high energies

In this paper we develop an approach to soft scattering processes at high energies which is based on two elements: the Good–Walker mechanism for low mass diffraction and multi-pomeron interactions for high mass diffraction. The principal idea, which allows us to specify the theory for pomeron interactions, is that the so called soft processes occur at rather short distances (r ² ∝1/〈p _t 〉² ∝ α′_ℙ≈0.01 GeV⁻²), where perturbative QCD is valid. The value of the pomeron slope α′_ℙ is obtained from a fit to the experimental data. Using this theoretical approach, we suggest a model that fits all soft data in the ISR-Tevatron energy range: total, elastic, single and double diffractive cross sections, as well as the t dependence of the differential elastic cross section, and the mass dependence of single diffraction. In this model we calculate the survival probability of diffractive Higgs production, and we obtain a value for this observable that is smaller than 1% at the LHC energy range.     

On the cross-section peaks for a heavy-quark bound state

We discuss the values of resonance peaks of the cross section of a heavy-quark bound state obtained by means of a Green function method applied to a Coulombic model and compare the result to the ϒ and J/ψ data.     

Results of the search for strange quark matter and Q-balls with the SLIM experiment

The SLIM experiment at the Chacaltaya high altitude laboratory was sensitive to nuclearites and Q-balls which could be present in the cosmic radiation as possible Dark Matter components. It was sensitive also to strangelets, i.e. small lumps of Strange Quark Matter predicted at such altitudes by various phenomenological models. The analysis of 427 m² of Nuclear Track Detectors exposed for 4.22 years showed no candidate event. New upper limits on the flux of downgoing nuclearites and Q-balls at the 90% C.L. were established. The null result also restricts models for strangelets propagation through the Earth atmosphere.     

AdS-QCD quark–antiquark potential,meson spectrum and tetraquarks

The AdS/QCD correspondence predicts the structure of the quark–antiquark potential in the static limit. We use this piece of information together with the Salpeter equation (Schrödinger equation with relativistic kinematics) and a short range hyperfine splitting potential to determine quark masses and the quark potential parameters from the meson spectrum. The agreement between theory and experimental data is satisfactory, provided one considers only mesons comprising at least one heavy quark. We use the same potential (in the one-gluon-exchange approximation) and these data to estimate the constituent diquark masses. Using these results as input we compute tetraquark masses using a diquark–antidiquark model. The masses of the states X(3872) or Y(3940) are predicted rather accurately. We also compute tetraquark masses with open charm and strangeness. Our result is that tetraquark candidates such as D _s (2317), D _s (2457) or X(2632) can hardly be interpreted as diquark–antidiquark states within the present approach.     

The axial form factor in the Nambu-Jona-Lasinio model

We give a general expression for the expectation value of the axial vector currentA _µ ^a in a system with baryon numberB=1, which arises as solution of theSU(2)—flavour Nambu-Jona-Lasinio model in the fermion-1-loop approximation. States with good spin and isospin quantum numbers are constructed by using the lowest order cranking approximation. Taking the self consistent solutions for such a system we calculate the axial form factorg _A(q ²) and the axial coupling constantg _A . The results can be checked by comparing the value of g_A with the one obtained from the radial integral or the asymptotic tail of the self consistent pion field by means of the PCAC relation.     

Abelian 2-form gauge theory: superfield formalism

We derive the off-shell nilpotent Becchi–Rouet–Stora–Tyutin (BRST) and anti-BRST symmetry transformations for all the fields of a free Abelian 2-form gauge theory by exploiting the geometrical superfield approach to the BRST formalism. The above four (3+1)-dimensional (4D) theory is considered on a (4, 2)-dimensional supermanifold parameterized by the four even spacetime variables x ^μ (with μ=0,1,2,3) and a pair of odd Grassmannian variables θ and (with ). One of the salient features of our present investigation is that the above nilpotent (anti-) BRST symmetry transformations turn out to be absolutely anticommuting due to the presence of a Curci–Ferrari (CF) type of restriction. The latter condition emerges due to the application of our present superfield formalism. The actual CF condition, as is well known, is the hallmark of a 4D non-Abelian 1-form gauge theory. We demonstrate that our present 4D Abelian 2-form gauge theory imbibes some of the key signatures of the 4D non-Abelian 1-form gauge theory. We briefly comment on the generalization of our superfield approach to the case of Abelian 3-form gauge theory in four, (3+1), dimensions of spacetime.     

Standard model and gravity from spinors

It is shown how the Lorentz and standard-model gauge groups can be unified by using algebraic spinors of the standard four-dimensional Clifford algebra, in left–right symmetric fashion. This defines a framework of unification with gravity and generates exactly a standard-model family of fermions, while a Pati–Salam unification group emerges, at the Planck scale, where (chiral) gravity decouples. We show that this low-energy broken phase emerges from the VEV of extended vierbein fields, which at this stage are assumed to be dynamically generated from a theory in the fully symmetric phase valid beyond the Planck scale (and whose consistency and dynamics is thus yet to be assessed) providing thus a geometrical and group-theoretical framework for the unification and breaking. At low energy, on the other hand, it is intriguing to find, as a remnant of this unification, new isospin-triplet spin-two particles that may naturally lie at the weak scale, providing a striking signal at the LHC.     

Relaxing the cosmological constraints on unparticle dark component

Unparticle physics has been an active field since the seminal work of Georgi. Recently, many constraints on unparticles from various observations have been considered in the literature. In particular, the cosmological constraints on the unparticle dark component put it in a serious situation. In this work, we try to find a way out of this serious situation, by including the possible interaction between dark energy and the unparticle dark component.     

Bose-Einstein correlations of neutral gauge bosons in pp collisions

The theory for Bose-Einstein correlations in case of neutral gauge bosons in pp collisions at high energies is presented. Based on quantum field theory at finite temperature, the two-particle Bose-Einstein correlations of neutral gauge bosons are carried out for the first time. As a result, the important parameters of the correlation functions can be obtained for the Z ⁰ Z ⁰ pairs. The article is published in the original.     

Dirac magnetic monopole production from photon fusion in proton collisions

We calculate the lowest-order cross-section for Dirac magnetic monopole production from photon fusion ( in p collisions at = 1.96 TeV, pp collisions at = 14 TeV, and we compare with Drell-Yan (DY) production. We find the total cross-section is comparable with DY at = 1.96 TeV and dominates DY by a factor > 50 at = 14 TeV. We conclude that both the and DY processes allow for a monopole mass limit m > 370 GeV based upon the null results of the recent monopole search at the Collider Detector at Fermilab (CDF). We also conclude that production is the leading mechanism to be considered for direct monopole searches at the Large Hadron Collider (LHC).     

Non-collective oblate states in121Te

Two new neutron-deficient isotopes,²¹³Pa and²¹⁴Pa were produced in complete fusion reactions of⁵¹V-ions with¹⁷⁰Er targets at (5.2–5.6) AMeV. The assignment was based on delayed evaporation residue - - time and position coincidences. The- decay energies of^213,214Pa were measured to be E=(8236±20) keV and E=(8116±20) keV, respectively. The half-lives of^213,214Pa were determined to be T_1/2=(5.3 _–1.6 ^+4.0 ms and T_1/2=(17 ±3) ms, respectively.This article was processed by the author using the LAT_EX style filecljour2 from Springer-Verlag.     

Gravitational anomaly and Hawking radiation of apparent horizon in FRW universe

Motivated by the successful applications of the anomaly cancellation method to derive Hawking radiation from various types of black hole spacetimes, we further extend the gravitational anomaly method to investigate the Hawking radiation from the apparent horizon of a FRW universe by assuming that the gravitational anomaly also exists near the apparent horizon of the FRW universe. The result shows that the radiation flux from the apparent horizon of the FRW universe measured by a Kodama observer is just the pure thermal flux. The result presented here will further confirm the thermal properties of the apparent horizon in a FRW universe.     

Cross sections of 102 element isotopes formation in the reactions of22Ne+236U and26Mg+232Th

The production cross sections of the isotopes²⁵²102,²⁵³102, and²⁵⁴102 were measured for the heavy ion fusion reactions of²²Ne+²³⁶U and²⁶Mg+²³²Th by using the kinematic separator VASSILISSA. The obtained excitation functions and the maximum production cross sections are compared with the ones for more asymmetric reactions leading to the same compound nucleus²⁵⁸102. The experimental cross sections and the results of statistical model calculations are compared and discussed.The authors express their gratitude to Prof. Yu. Ts. Oganessian for his great interest and support of this work, to Drs. E.A. Cherepanov, Yu.A. Muzychka and B.I. Pustylnik for the calculations and for the useful discussions.     

Level density fluctuations and characterization of chaos in the realistic model spectra for odd-odd nuclei

Statistical properties of the realistic energy spectra of the odd-odd nuclei¹⁰⁶Ag,¹⁹⁸Au,¹³⁴Cs,⁴⁰K and⁹⁴Rb, calculated within the Interacting Boson Fermion Fermion Model, are investigated by means of theΔ ₃ statistics and the Nearest Neighbor Spacing Distribution method. New probability distribution function, which describes well the calculated results and enables the characterization of chaos with a physically meaningfull parameter, is proposed. Level spacing fluctuations of the examined nuclei exhibit the transitional behavior between Poisson and GOE limits, revealing different degrees of chaoticity in their dynamics. Communicated by X. Campi     

A field-theoretic model for Hodge theory

We demonstrate that the four-dimensional (4D) ((3+1)-dimensional) free Abelian 2-form gauge theory presents a tractable field-theoretical model for the Hodge theory where the well-defined symmetry transformations correspond to the de Rham cohomological operators of differential geometry. The conserved charges, corresponding to the above continuous symmetry transformations, obey an algebra that is reminiscent of the algebra obeyed by the cohomological operators. The discrete symmetry transformation of the theory represents the realization of the Hodge duality operation that exists in the relationship between the exterior and co-exterior derivatives of differential geometry. Thus, we provide the realizations of all the mathematical quantities, associated with the de Rham cohomological operators, in the language of the symmetries of the present 4D free Abelian 2-form gauge theory.     

Small sample size effects in statistical analyses of eigenvalue distributions

The effects of small sample sizes on the statistical analysis of eigenvalue distributions were analyzed numerically. The behavior of the nearest-neighbor spacing distribution, the ₃ statistic, and the linear correlation coefficient between adjacent spacings was studied, and the effects of missing or spurious levels and of unfolding an energy-dependent level density were explored. For small sample sizes the nearest-neighbor spacing distribution appears to be the most reliable of these three statistics.We wish to thank T. Guhr for his computer code to calculate GOE spectra and T. von Egidy for discussions concerning the energy dependence of level densities. This work was supported in part by the US Department of Energy under Grant Nos. DE-FG05-87ER40353 and DE-FG05-88ER40441.