QCD fits in diffractive DIS revisited

A new method of extracting diffractive parton distributions is presented which avoids the use of Regge theory ansatz and is in much closer relation with the factorization theorem for diffarctive hard processes.Comment: proceeding to PHOTON11 conferenc

Spectroscopy at B-factories Using Hard Photon Emission

The process of hard photon emission by initial electrons (positrons) at B-factories is discussed. It is shown that studies of the bottomonium spectroscopy will be feasible for the planned integrated luminosity of the B-factory experiments.Comment: 9 pages, Latex, 1 fugure, Submitted to Int.Jour.Mod.Phys.

A Deeply Virtual Compton Scattering Amplitude

A factorized Regge-pole model for deeply virtual Compton scattering is suggested. The use of an effective logarithmic Regge-Pomeron trajectory provides for the description of both ``soft'' (small $|t|$) and ``hard'' (large $|t|$) dynamics. The model contains explicitly the photoproduction and the DIS limits and fits the existing HERA data on deeply virtual Compton scattering.Comment: 10 pages, 3 figure

Pion production in deeply virtual Compton scattering

Using a soft pion theorem based on chiral symmetry and a $\Delta(1232)$ resonance model we propose an estimate for the production cross section of low energy pions in the deeply virtual Compton scattering (DVCS) process. In particular, we express the $e p \to e \gamma \pi N$ processes in terms of generalized parton distributions. We provide estimates of the contamination of the $e p \to e \gamma p$ DVCS observables due to this associated pion production processes when the experimental data are not fully exclusive, for a set of kinematical conditions representative of present or planned experiments at JLab, HERMES and COMPASS.Comment: 50 pages, 22 figure

Probing color coherence effects in pp collisions at [Formula: see text].

A study of color coherence effects in pp collisions at a center-of-mass energy of 7[Formula: see text] is presented. The data used in the analysis were collected in 2010 with the CMS detector at the LHC and correspond to an integrated luminosity of 36 pb[Formula: see text]. Events are selected that contain at least three jets and where the two jets with the largest transverse momentum exhibit a back-to-back topology. The measured angular correlation between the second- and third-leading jet is shown to be sensitive to color coherence effects, and is compared to the predictions of Monte Carlo models with various implementations of color coherence. None of the models describe the data satisfactorily

Measurements of differential and double-differential Drell-Yan cross sections in proton-proton collisions at [Formula: see text][Formula: see text].

Measurements of the differential and double-differential Drell-Yan cross sections in the dielectron and dimuon channels are presented. They are based on proton-proton collision data at [Formula: see text] recorded with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7[Formula: see text]. The measured inclusive cross section in the [Formula: see text] peak region (60-120[Formula: see text]), obtained from the combination of the dielectron and dimuon channels, is [Formula: see text], where the statistical uncertainty is negligible. The differential cross section [Formula: see text] in the dilepton mass range 15-2000[Formula: see text] is measured and corrected to the full phase space. The double-differential cross section [Formula: see text] is also measured over the mass range 20 to 1500[Formula: see text] and absolute dilepton rapidity from 0 to 2.4. In addition, the ratios of the normalized differential cross sections measured at [Formula: see text] and 8[Formula: see text] are presented. These measurements are compared to the predictions of perturbative QCD at next-to-leading and next-to-next-to-leading (NNLO) orders using various sets of parton distribution functions (PDFs). The results agree with the NNLO theoretical predictions computed with fewz 3.1 using the CT10 NNLO and NNPDF2.1 NNLO PDFs. The measured double-differential cross section and ratio of normalized differential cross sections are sufficiently precise to constrain the proton PDFs

Search for decays of stopped long-lived particles produced in proton-proton collisions at [Formula: see text].

A search has been performed for long-lived particles that could have come to rest within the CMS detector, using the time intervals between LHC beam crossings. The existence of such particles could be deduced from observation of their decays via energy deposits in the CMS calorimeter appearing at times that are well separated from any proton-proton collisions. Using a data set corresponding to an integrated luminosity of 18.6[Formula: see text] of 8[Formula: see text] proton-proton collisions, and a search interval corresponding to 281 h of trigger livetime, 10 events are observed, with a background prediction of [Formula: see text] events. Limits are presented at 95 % confidence level on gluino and top squark production, for over 13 orders of magnitude in the mean proper lifetime of the stopped particle. Assuming a cloud model of R-hadron interactions, a gluino with mass [Formula: see text]1000[Formula: see text] and a top squark with mass [Formula: see text]525[Formula: see text] are excluded, for lifetimes between 1 [Formula: see text]s and 1000[Formula: see text]. These results are the most stringent constraints on stopped particles to date

Measurement of the [Formula: see text] production cross section in the all-jets final state in pp collisions at [Formula: see text][Formula: see text].

The cross section for [Formula: see text] production in the all-jets final state is measured in pp collisions at a centre-of-mass energy of 8 [Formula: see text] at the LHC with the CMS detector, in data corresponding to an integrated luminosity of 18.4 [Formula: see text]. The inclusive cross section is found to be [Formula: see text] [Formula: see text]. The normalized differential cross sections are measured as a function of the top quark transverse momenta, [Formula: see text], and compared to predictions from quantum chromodynamics. The results are reported at detector, parton, and particle levels. In all cases, the measured top quark [Formula: see text] spectra are significantly softer than theoretical predictions