Conceptual Design for a Polarized Proton-Antiproton Collider Facility at Gsi

Two possible options of polarized proton-antiproton collider at the future HESR storage ring are considered. It is shown that the modifications of the present HESR project which are needed to arrange for the polarized proton-antiproton collisions are relatively moderate. An achievable luminosity of 5x10^31 cm^-2 sec^-1 will provide a possibility to carry out experiments in the CM energy range 10-30 GeV, a particularly interesting option for Drell-Yan physics

Residue formulas for prepotentials, instanton expansions and conformal blocks

We study the extended prepotentials for the S-duality class of quiver gauge theories, considering them as quasiclassical tau-functions, depending on gauge theory condensates and bare couplings. The residue formulas for the third derivatives of extended prepotentials are proven, which lead to effective way of their computation, as expansion in the weak-coupling regime. We discuss also the differential equations, following from the residue formulas, including the WDVV equations, proven to be valid for the SU(2) quiver gauge theories. As a particular example we consider the constrained conformal quiver gauge theory, corresponding to the Zamolodchikov conformal blocks by 4d/2d duality. In this case part of the found differential equations turn into nontrivial relations for the period matrices of hyperelliptic curves

The specificity of searches for W ′, Z ′ and γ ′ coming from extra dimensions

We discuss the specificity of searches for hypothetical W ′, Z ′ and γ ′ bosons at hadron colliders in single top quark and μ + ν μ production and Drell-Yan processes assuming these particles to be the Kaluza-Klein excitations of the gauge bosons of the Standard Model. In this case any process mediated by W is also mediated by the whole KK tower of its excitations, whereas to the processes mediated by Z and γ there is not only a contribution from their KK towers, but also from that of the graviton. The contributions of the towers above W ′, Z ′ and γ ′ and above the first excitation of the graviton are included with the help of effective four-fermion Lagrangians. We compute the cross-sections of these processes taking into account the contributions of the Standard Model gauge bosons, of their first KK modes and of the corresponding KK towers and discuss the impact of the interference between them. For pp-collisions at the LHC with the center of mass energy 14 TeV we found specific changes of the distribution tails due to the interference effects. Such a modification of distribution tails is characteristic for the processes mediated by particles coming from extra dimensions and should always be taken into account when looking for them

On the possibility to detect the Higgs decay H→bb¯ in the associated Z+bb¯ production at the LHC

We investigate the possibility to detect the scalar Higgs boson decay H→bb¯ in the associated Z and bb¯ production at the LHC using the kT -factorization QCD approach. Our consideration is based on the off-shell (i.e. depending on the transverse momenta of initial quarks and gluons) production amplitudes of q∗q¯∗→ZH→Zq′q¯′ , q∗q¯∗→Zq′q¯′ , and g∗g∗→Zq′q¯′ partonic subprocesses supplemented with the Catani–Ciafoloni–Fiorani–Marchesini (CCFM) dynamics of parton densities in a proton. We argue that the H→bb¯ signal could be observed at large transverse momenta near the Higgs boson peak despite the overwhelming QCD background, and we point out the important role of angular correlations between the produced Z boson and b -quarks

A measurement of the neutron lifetime using the method of storage of ultracold neutrons and detection of inelastically up-scattered neutrons

We present estimations of systematic corrections and results of their experimental studies for our neutron lifetime experiment carried out in 2008–2010 at ILL. Taking into account these systematic corrections, we reduce the data of three independent sets of measurements (obtained during period 2008–2010) performed with different energy spectra of ultracold neutrons (UCNs) at different trap temperatures to the mean neutron lifetime value equal to 880.2(1.2) s

Higher harmonics of azimuthal anisotropy in relativistic heavy-ion collisions in HYDJET++ model

The LHC data on azimuthal anisotropy harmonics from PbPb collisions at center-of-mass energy 2.76 TeV per nucleon pair are analyzed and interpreted in the framework of the HYDJET++ model. The cross-talk of elliptic <math><msub><mi>v</mi><mn>2</mn></msub></math> and triangular <math><msub><mi>v</mi><mn>3</mn></msub></math> flow in the model generates both even and odd harmonics of higher order. Comparison with the experimental data shows that this mechanism is able to reproduce the <math><msub><mi>p</mi><mi mathvariant="normal">T</mi></msub></math> and centrality dependencies of quadrangular flow <math><msub><mi>v</mi><mn>4</mn></msub></math> , and also the basic trends for pentagonal <math><msub><mi>v</mi><mn>5</mn></msub></math> and hexagonal <math><msub><mi>v</mi><mn>6</mn></msub></math> flows

Spin Structure Function of the Deuteron in the Resonance Region and the GDH Sum Rule for the Neutron

The nuclear effects in the spin-dependent structure function $g_1$ of the deuteron are studied in the kinematics of future experiments at CEBAF, ($\nu \leq 3~GeV, ~Q^2 \leq 2~GeV^2$). The magnitude of the nuclear effects is found to be significantly larger than the one occurring in deep inelastic scattering ($\nu\to \infty, ~Q^2\to \infty$). We discuss the mechanism leading to large effects in the region of the nucleon resonances. A possibility to measure the neutron structure functions in the CEBAF experiments with deuterium is analysed, and conclusions about the experimental study of the $Q^2$ dependence of the Gerasimov-Drell-Hearn Sum Rule for the neutron are drawn

First πK atom lifetime and πK scattering length measurements

The results of a search for hydrogen-like atoms consisting of <math altimg="si1.gif" xmlns="http://www.w3.org/1998/Math/MathML"><msup><mrow><mi>π</mi></mrow><mrow><mo>∓</mo></mrow></msup><msup><mrow><mi>K</mi></mrow><mrow><mo>±</mo></mrow></msup></math> mesons are presented. Evidence for πK atom production by 24 GeV/c protons from CERN PS interacting with a nickel target has been seen in terms of characteristic πK pairs from their breakup in the same target ( <math altimg="si2.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mn>178</mn><mo>±</mo><mn>49</mn></math> ) as well as in terms of produced πK atoms ( <math altimg="si3.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mn>653</mn><mo>±</mo><mn>42</mn></math> ). Using these results, the analysis yields a first value for the πK atom lifetime of <math altimg="si4.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mi>τ</mi><mo>=</mo><mo stretchy="false">(</mo><msubsup><mrow><mn>2.5</mn></mrow><mrow><mo>−</mo><mn>1.8</mn></mrow><mrow><mo>+</mo><mn>3.0</mn></mrow></msubsup><mo stretchy="false">)</mo><mtext> fs</mtext></math> and a first measurement of the S-wave isospin-odd πK scattering length <math altimg="si5.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mo stretchy="false">|</mo><msubsup><mrow><mi>a</mi></mrow><mrow><mn>0</mn></mrow><mrow><mo>−</mo></mrow></msubsup><mo stretchy="false">|</mo><mo>=</mo><mfrac><mn>1</mn><mn>3</mn></mfrac><mo stretchy="false">|</mo><msub><mrow><mi>a</mi></mrow><mrow><mn>1</mn><mo stretchy="false">/</mo><mn>2</mn></mrow></msub><mo>−</mo><msub><mrow><mi>a</mi></mrow><mrow><mn>3</mn><mo stretchy="false">/</mo><mn>2</mn></mrow></msub><mo stretchy="false">|</mo><mo>=</mo><mo stretchy="false">(</mo><msubsup><mrow><mn>0.11</mn></mrow><mrow><mo>−</mo><mn>0.04</mn></mrow><mrow><mo>+</mo><mn>0.09</mn></mrow></msubsup><mo stretchy="false">)</mo><msubsup><mrow><mi>M</mi></mrow><mrow><mi>π</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msubsup></math> ( <math altimg="si6.gif" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>a</mi></mrow><mrow><mi>I</mi></mrow></msub></math> for isospin I )

Transversity in exclusive vector-meson leptoproduction

The role of transversity or helicity-flip generalized parton distributions (GPDs) in leptoproduction of vector mesons is investigated within the framework of the handbag approach. The transversity GPDs in combination with twist-3 meson wave functions occur in the amplitudes for transitions from a transversely polarized virtual photon to a longitudinal polarized vector meson. The importance of the transversity GPDs can be examined in some of the spin density matrix elements and in transverse target spin asymmetries. Using suitable parametrizations of both helicity-flip and -non-flip GPDs, which are essentially taken from our previous papers, we estimate these observables and compare the results with available data

The exclusive limit of the pion-induced Drell–Yan process

Based on previous studies of hard exclusive leptoproduction of pions in which the essential role of the pion pole and the transversity generalized parton distributions (GPDs) has been pointed out, we present predictions for the four partial cross sections of the exclusive Drell–Yan process, π−p→l−l+n