Higher Twist Effects in Photon-Photon Collisions

In this article, we investigate the contribution of the high twist Feynman diagrams to the large $p_{T}$ single pseudoscalar and vector mesons inclusive production cross section in two-photon collisions and we present the general formulae for the high and leading twist differential cross sections. The pion wave function where two non-trivial Gegenbauer coefficients $a_2$ and $a_4$ have been extracted from the CLEO data, Braun-Filyanov pion wave function, the asymptotic and the Chernyak-Zhitnitsky wave functions are used in the calculations. For $\rho$-meson we used Ball-Braun wave function. The results of all the calculations reveal that the high twist cross sections, the ratio R, the dependence transverse momentum $p_{T}$ and the rapidity $y$ of meson in $\Phi_{CLEO}(x,Q^2)$ wave function case is very close to the $\Phi_{asy}(x)$ asymptotic wave function case. It is shown that the high twist contribution to the cross section depends on the choice of the meson wave functions.Comment: REVTEX4, 23 pages, 7 figure

Meson Production in Proton-Proton Collisions in the Naive Non-Abelianization Approximation and the Role of Infrared Renormalons

We calculate the "naive non-abelianization" (NNA) contributions of the higher-twist Feynman diagrams to the large-$p_T$ inclusive pion production cross section in proton-proton collisions in the case of the running coupling and frozen coupling approaches. We compare the resummed "naive non-abelianization" higher-twist cross sections with the ones obtained in the framework of the frozen coupling approach and leading-twist cross section. The structure of infrared renormalon singularities of the higher twist subprocess cross section and it's resummed expression are found. We discuss the phenomenological consequences of possible higher-twist contributions to the pion production in proton-proton collisions in within NNA.Comment: 17 pages, 9 figure

Investigation of the nuetralino pair production at LHC

In this article, we investigate the Drell-Yan process of the light neutralino pair $\widetilde{\chi}_{i}^{0}\widetilde{\chi}_{j}^{0}$ ($i,j=1,2$) productions at proton-proton collisions and we present the general formulate for the differential cross sections. We conduct an extensive examination of the dependence of the total cross section of the subprocesses $q \bar q \to \widetilde \chi_{i}^{0}\widetilde\chi_{j}^{0}$ on the beam energy, on the mass of the squarks and also on the $M_2$ gaugino for the three extremely different scenarios. For all three cases, the outcomes are as follows. The dependence of the total cross section of the subprocesses $q \bar q \to \widetilde \chi_{i}^{0} \widetilde \chi_{j}^{0}$ on the beam energy is dominated by one of the subprocesses, $q \bar q \to \widetilde \chi_{1}^{0} \widetilde \chi_{2}^{0}$. On the other hand, the dependence of the total cross section of the subprocesses $q \bar q \to \widetilde \chi_{i}^{0} \widetilde \chi_{j}^{0}$ on the mass of the squarks is dominated by one of the subprocesses, $q \bar q \to \widetilde \chi_{1}^{0} \widetilde \chi_{2}^{0}$. We derive there from that our findings may lead to new insights relating to experimental investigations and these dependencies may be used as bases of an experimental research for the neutralino pair at LHC.Comment: 38pp, 22 figures, ReVTeX4, (Baku State University, Azerbaijan, and Erciyes University, Kayseri, Turkey

Higher Twist Effects in Proton-Proton Collisions

In this article, we investigate the contribution of the high twist Feynman diagrams to the large-$p_T$ pion production cross section in proton-proton collisions and we present the general formulae for the high and leading twist differential cross sections. The pion wave function where two non-trivial Gegenbauer coefficients $a_2$ and $a_4$ have been extracted from the CLEO data, two other pion model wave functions, $P_2$, $P_3$, the asymptotic and the Chernyak-Zhitnitsky wave functions are used in the calculations. The results of all the calculations reveal that the high twist cross sections, the ratios $R$, $r$, the dependence transverse momentum $p_T$ and the rapidity $y$ of pion in the $\Phi_{CLEO}(x,Q^2)$ wave function case is very close to the $\Phi_{asy}(x)$ asymptotic wave function case. It is shown that the high twist contribution to the cross section depends on the choice of the meson wave functions.Comment: 28 pages 18 figures RevTex

Infrared renormalons and single meson production in proton-proton collisions

In this article, we investigate the contribution of the higher twist Feynman diagrams to the large-$p_T$ inclusive pion production cross section in proton-proton collisions and present the general formulae for the higher twist differential cross sections in the case of the running coupling and frozen coupling approaches. The structure of infrared renormalon singularities of the higher twist subprocess cross section and the resummed expression (the Borel sum) for it are found. We compared the resummed higher twist cross sections with the ones obtained in the framework of the frozen coupling approximation and leading twist cross section. We obtain, that ratio $R$ for all values of the transverse momentum $p_{T}$ of the pion identical equivalent to ratio $r$. It is shown that the resummed result depends on the choice of the meson wave functions used in calculation. Phenomenological effects of the obtained results are discussed.Comment: 28 pages, 13 figure