36.
Combined inclusive diffractive cross sections measured with forward proton
spectrometers at HERA

Valentina Sola
(Universita e INFN (IT))

3/27/12, 9:00 AM

Diffraction and vector mesons

A combination of the inclusive diffractive cross section measurements made by the H1 and ZEUS Collaborations at
HERA is presented. The analysis uses diffractive deep inelastic scattering data measured by means of proton spectrometers.
Correlations of systematic uncertainties are taken into account by the combination method,resulting in improved precision.
The combined data cover the range...

David Salek
(CERN)

3/27/12, 9:20 AM

Diffraction and vector mesons

First measurements are presented of the diffractive cross section
$\sigma_{ep \rightarrow eXY}$ at centre-of-mass energies $\sqrt{s}$ of
225 and 252 GeV, together with a precise new measurement at $\sqrt{s}$ of
319 GeV, using data taken with the H1 detector in the years 2006 and 2007.
Together with previous H1 data at $\sqrt{s}$ of 301 GeV, the measurements
are used to extract the...

Emmanuel Sauvan
(LAPP (IN2P3/CNRS))

3/27/12, 9:40 AM

Diffraction and vector mesons

Measurements of the cross section for the diffractive process ep -> eXY are presented,
where Y is a proton or a low mass proton excitation carrying a fraction 1 − xIP > 0.95
of the incident proton longitudinal momentum and the squared four-momentum transfer
at the proton vertex satisfying MY < 1.6 GeV and |t| < 1.0 GeV^2. Using data taken
by the H1 experiment, the cross section is measured...

Richard Polifka
(University of Toronto (CA))

3/27/12, 10:00 AM

Diffraction and vector mesons

The cross section of diffractive deep-inelastic scattering ep \rightarrow eXp
is measured, where the system X contains at least two jets and the leading
final state proton is detected in the H1 Forward Proton Spectrometer. The
measurement is performed for fractional proton longitudinal momentum loss
xIP < 0.1 and covers the range 0.1 < |t| < 0.7 GeV2 in squared four-momentum
transfer...

Federico Alberto Ceccopieri
(Fondazione Angelo Della Riccia Ente Morale)

3/27/12, 11:00 AM

Diffraction and vector mesons

A new method for the extraction of diffractive parton distributions is presented which avoids the use of Regge theory ansatz and is in much closer relation with the factorization theorem for diffractive hard processes.

Mrs
Sara Taheri Monfared
(Semnan university and IPM)

3/27/12, 11:20 AM

Diffraction and vector mesons

We extract diffractive parton distribution functions (DPDFs) and diffractive structure functions from the most recent H1 and ZEUS diffractive DIS data obtained by various methods. We consider Pomeron as an object with parton distribution function, evolving according to the next-to-leading order (NLO) DGLAP equations within the framework of the ‘Fixed Flavour Number Scheme’ (FFNS). Having...

Mariusz Sadzikowski
(Jagiellonian University)

3/27/12, 11:40 AM

Diffraction and vector mesons

HERA data on diffractive DIS show deviations from twist 2 DGLAP predictions below Q^2 5 GeV^2 at low x_P, which may reach up to 100%. These deviations are consistent with higher twists effects extracted from the saturation model. It is a first direct evidence for the higher twists in DIS. This finding affects determination of the diffractive parton densities that are used for the predictions...

Leszek Motyka
(Jagellonian Univerisity)

3/27/12, 12:00 PM

Diffraction and vector mesons

We present new results on determination of higher twist contributions in diffractive DIS and compare them to the inclusive DIS case. In both cases the framework for the estimates is provided by the saturation model. We discuss the methods of higher twist extraction from the saturation model and compare the results for DIS and DDIS. We point out a striking difference in higher twist importance...

Dr
Erik Brücken
(Helsinki Institute of Physics (FI))

3/27/12, 2:00 PM

Diffraction and vector mesons

We report central exclusive production results studied at the Run II Collider Detector at Fermilab with focus on our recently published paper on the first observation of exclusive γγ production in pp ̄ collisions at √s = 1.96 TeV at the Tevatron. In particular, starting from earlier studies by the CDF collaboration, we discuss exclusive dijet, dilepton, Z, J/Ψ and χc productions and finally...

Dermot Moran
(Univ Manchester)

3/27/12, 2:20 PM

Diffraction and vector mesons

We report on studies of exclusive dimuon production, using LHCb experimental data. Exclusively produced muon pairs can be produced by two photon fusion (a QED process ideally suited to obtaining a precise integrated luminosity measure), or by resonance production. We show results for exclusive dimuon production, and observations of the exclusive J/psi. psi‘ and chi_c states, obtained with data...

Wenbo Li
(Peking University (CN))

3/27/12, 2:40 PM

Diffraction and vector mesons

We present the search for exclusive diphoton production and
the measurement of exclusive dilepton production, based on the data
recorded by the CMS experiment at the LHC in 2010. An upper limit on the
cross section is set for exclusive diphoton production, which is
compared with the QCD perturbative theory predictions using different
PDF sets. The exclusive dielectron production provides...

Dr
Marek Tasevsky
(Acad. of Sciences of the Czech Rep. (CZ))

3/27/12, 3:00 PM

Diffraction and vector mesons

We investigate the prospects for Central Exclusive Diffractive (CED)
production of BSM Higgs bosons at the LHC using forward proton detectors installed at 220~m and 420~m distance around ATLAS and / or CMS.
We update a previous analysis for the MSSM taking into account
improvements in the theoretical calculations and the most
recent exclusion bounds from the LHC.
We extend the MSSM...

Adrien Besse
(L)

3/27/12, 3:20 PM

Diffraction and vector mesons

Exclusive leptoproduction of vector mesons has been the subject of recent significant progress, both theoretically and experimentally. In particular, the hard regime with a highly virtual photon exchange allows to separate a short distance dominated amplitude of hard subprocess from suitably defined hadronic objects. However, a consistent picture is still missing, in particular for...

Emilien Chapon
(Centre d'Etudes de Saclay (CEN Saclay)-Unknown-Unknown)

3/27/12, 3:40 PM

Diffraction and vector mesons

We study the W/Z pair production via two-photon exchange at the LHC and give the sensitivities on trilinear and quartic gauge anomalous couplings between photons and W/Z bosons. Tagging the protons in the final state in the ATLAS Forward Physics detectors as an example allows to improve the reach on anomalous couplings by four orders of magnitude reaching the values predicted by...

Antonio Vilela Pereira
(Universita e INFN (IT))

3/27/12, 4:50 PM

Diffraction and vector mesons

The talk will present CMS measurements on diffractive W and
dijet production in p-p collisions at 0.9, 2.36 and 7 TeV.

Dr
Mickey Chiu
(Brookhaven National Lab)

3/27/12, 5:10 PM

Diffraction and vector mesons

One of the fundamental goals of the PHENIX experiment is to understand the structure of cold nuclear matter, since this serves as the initial state for heavy-ion collisions. Knowing the initial state is vital for interpreting measurements from heavy-ion collisions. Moreover, the structure of the cold nucleus by itself is interesting since it is a test-bed for our understanding of QCD. In...

Prof.
Antoni Szczurek
(Institute of Nuclear Physics Krakow (Poland))

3/27/12, 5:30 PM

Diffraction and vector mesons

We discuss central exclusive production of $W^+W^-$ pairs in proton-proton collisions at LHC. Several observables related to this
process are calculated. Predictions for the total cross section and differential distributions in rapidity and transverse momentum of $W^{\pm}$ and $WW$ invariant mass are presented.
We show results for different polarization states of the final $W^{\pm}$ bosons....

Jacek Ciborowski
(University of Warsaw)

3/28/12, 4:00 PM

Diffraction and vector mesons

The exclusive photoproduction reaction gamma p -> Upsilon(1S) p has been studied with the ZEUS detector in ep collisions
at HERA using an integrated luminosity of 468pb-1.
The measurement covers the kinematic range 60 < W < 220 GeV and
Q2 < 1 GeV2, where W is the photon--proton centre-of-mass energy
and Q2 is the photon virtuality. The exponential slope, b, of the t dependence of the...

Dr
Justyna Tomaszewska
(DESY)

3/28/12, 4:20 PM

Diffraction and vector mesons

The exclusive electroproduction of two pions in the mass range
0.4 < M(pipi) < 2.5 GeV has been studied with the ZEUS
detector at HERA using an integrated luminosity of
82 pb-1. The analysis was carried out in the kinematic range of
2 < Q2 < 80 GeV2, 32 < W <180 GeV and |t|<0.6 GeV,
where Q2 is the photon virtuality, W is the
photon-proton centre-of-mass energy and t is the...

Prof.
Ruben Sandapen
(University of Moncton (Canada))

3/28/12, 4:40 PM

Diffraction and vector mesons

We obtain a very good description of the current HERA data on diffractive rho electroproduction using a holographic
light-cone wavefunction for the rho meson. This holographic wavefunction is obtained using the Brodsky and de Teramond
correspondance between hadronic modes in AdS space and light-cone wavefunctions in physical spacetime. We also show the
corresponding holographic Distribution...

Prof.
Kazuhiro Tanaka
(Juntendo University)

3/28/12, 5:00 PM

Diffraction and vector mesons

In the conventional b_* model for the Collins–Soper–Sterman resummation,
the resummed form factor is accompanied by the nonperturbative gaussian form factor, and
it is known that the nonperturbative parameter associated with the latter exhibits the strong dependence on the logarithm of
the vector boson invariant mass.
On the other hand, an another approach to treat the impact parameter (b...

Prof.
Alessandro Papa
(University of Calabria and INFN Cosenza (Italy))

3/29/12, 9:00 AM

Diffraction and vector mesons

We calculate in the next-to-leading order the impact factor (vertex) for the production of a forward high-p_T jet, in the approximation of small aperture of the jet cone in the pseudorapidity-azimuthal angle plane. The final expression for the vertex turns out to be simple and easy to implement in numerical calculations.

Clara Salas
(IFT)

3/29/12, 9:20 AM

Diffraction and vector mesons

An iterative solution best suited for a Monte Carlo implementation for the non-forward BFKL equation is presented and possible applications discussed. We introduce running coupling effects in a way compatible with the bootstrap, fundamental condition for gluon reggeization and see how this naturally leads to renormalon effects in the infrared.

Pavel Ruzicka
(Acad. of Sciences of the Czech Rep. (CZ))

3/29/12, 9:40 AM

Diffraction and vector mesons

Transverse energy distributions and regions of low activity in proton-proton scattering events
are sensitive to soft physics, low x and diffractive processes, and have been measured in inclusive
"minimum bias" scatters as well as in dijet events at sqrt(s) = 7 TeV. In the inclusive analysis,
cross sections are measured differentially in terms of Delta eta F, the larger of the...

José Daniel Madrigal
(IFT UAM/CSIC, Madrid)

3/29/12, 11:00 AM

Diffraction and vector mesons

Lipatov's high-energy effective action is a very promising tool for computations in the Regge limit beyond leading order. Its use has been however restricted to tree-level calculations for many years. Recently a regularization/subtraction prescription was proposed that allows to extend the formalism to deal with loops in a consistent way. We illustrate the procedure with the computation of the...

Dr
Marat Siddikov
(UTFSM)

3/29/12, 11:20 AM

Diffraction and vector mesons

In this talk we present the results of the diffractive single-pion production on the protons and nuclei (both for the coherent and incoherent cases). We demonstrate that all the evaluations which are based on Adler relation (AR) are valid only in the region up to 10 GeV, in the regime of short lifetime of heavy hadronic fluctuations. At higher energies, when all the relevant time scales...

Dr
Jeffrey Berger
(Penn State University (USA))

3/29/12, 11:40 AM

Diffraction and vector mesons

In previous numerical work the solution to the BK evolution equation
with impact parameter dependence was calculated with modeled confinement effects.
This solution is used to calculate diffractive cross sections
for the vector mesons J/Psi, Rho, and Phi. In order to bring the
numerical results into agreement with HERA data modification to the
photon wavefunction is necessary. This...

Dr
Krzysztof Kutak
(Instytut Fizyki Jadrowej Polskiej Akademii Nauk)

3/29/12, 12:00 PM

Diffraction and vector mesons

Motivated by the regime of QCD explored nowadays at LHC where both the total energy of collision and momenta transfers are high, evolution equations of high energy factorization are investigated.
Briefly we overview results obtained so far for proton proton collisions within high energy factorization approach for jet related observables and we give some predictions for proton lead. This...

Dr
Michal Deak
(Universidade de Santiago de Compostela)

3/29/12, 12:20 PM

Diffraction and vector mesons

We compare two Monte Carlo implementations of resummation schemes for the description of parton evolution at small values of Bjorken x. One of them if based on the BFKL evolution equation. The other one is based on the CCFM partonic kernel where QCD coherence effects are introduced. It has been argued that both approaches agree with each other in the x to 0 limit. We show that this is not the...