Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userRecent results on Central Exclusive Production with the STAR detector
259
0
0.0
(
0
)
Authors
Rafal Sikora
Ask ChatGPT about the research
No Arabic abstract
We present results on the Central Exclusive Production of charged particle pairs $h^{+}h^{-}$ ($h = pi, K, p$), $ppto p^prime+h^{+}h^{-}+p^prime$, obtained with the STAR experiment at RHIC in proton-proton collisions at a center-of-mass energy of $sqrt{s} = 200$ GeV. All final-state particles were reconstructed, including forward-scattered protons detected in the Roman Pot system. As a result, the Double Pomeron Exchange (DPE) events were selected and the non-exclusive backgrounds were efficiently rejected. Differential fiducial cross sections were measured as functions of observables related to the central hadronic final state and to the forward-scattered protons. The measured cross sections were compared to phenomenological model predictions based on the DPE. We also present preliminary results on the measurement of the same physics process at higher collision energy $sqrt{s} = 510$ GeV. The data demonstrate features similar to those observed at $sqrt{s} = 200$ GeV.
rate research
Read More
We report on the measurement of the Central Exclusive Production of charged particle pairs $h^{+}h^{-}$ ($h = pi, K, p$) with the STAR detector at RHIC in proton-proton collisions at $sqrt{s} = 200$ GeV. The charged particle pairs produced in the reaction $ppto p^prime+h^{+}h^{-}+p^prime$ are reconstructed from the tracks in the central detector, while the forward-scattered protons are measured in the Roman Pot system. Differential cross sections are measured in the fiducial region, which roughly corresponds to the square of the four-momentum transfers at the proton vertices in the range $0.04~mbox{GeV}^2 < -t_1 , -t_2 < 0.2~mbox{GeV}^2$, invariant masses of the charged particle pairs up to a few GeV and pseudorapidities of the centrally-produced hadrons in the range $|eta|<0.7$. The measured cross sections are compared to phenomenological predictions based on the Double Pomeron Exchange (DPE) model. Structures observed in the mass spectra of $pi^{+}pi^{-}$ and $K^{+}K^{-}$ pairs are consistent with the DPE model, while angular distributions of pions suggest a dominant spin-0 contribution to $pi^{+}pi^{-}$ production. The fiducial $pi^+pi^-$ cross section is extrapolated to the Lorentz-invariant region, which allows decomposition of the invariant mass spectrum into continuum and resonant contributions. The extrapolated cross section is well described by the continuum production and at least three resonances, the $f_0(980)$, $f_2(1270)$ and $f_0(1500)$, with a possible small contribution from the $f_0(1370)$. Fits to the extrapolated differential cross section as a function of $t_1$ and $t_2$ enable extraction of the exponential slope parameters in several bins of the invariant mass of $pi^+pi^-$ pairs. These parameters are sensitive to the size of the interaction region.
The ALICE experiment at the Large Hadron Collider (LHC) at CERN consists of a central barrel, a muon spectrometer and additional detectors for trigger and event classification purposes. The low transverse momentum threshold of the central barrel gives ALICE a unique opportunity to study the low mass sector of central exclusive production at the LHC.
Various aspects of forward physics have been studied by the ATLAS collaboration using data from Run I at the LHC. In this text, main results of three published analyses are summarized, based on data from proton-proton collisions at $sqrt{s} = 7$ or 8 TeV collected between 2010 and 2012. One analysis deals with diffractive signature with at least two jets in the final state, the other two study exclusive production of a pair of leptons or W bosons.
The measurement of exclusive $e^+e^-$ to hadrons processes is a significant part of the physics program of $BABAR$ experiment, aimed to improve the calculation of the hadronic contribution to the muon $g-2$ and to study the intermediate dynamics of the processes. We present the most recent results obtained by using the full data set of about 470,fb$^{-1}$ collected by the BABAR detector at the PEP-II $e^+e^-$ collider at a center-of-mass energy of about 10.6 GeV. In particular, we report the results on $e^+e^-$ annihilation into six- and seven-pion final states. The study of the very rich dynamics of these processes can help to understand the difference seen between the QCD prediction and the sum of exclusive cross sections in the energy region around 2 GeV, thus improving the precision on the total hadronic cross section and of the $g-2$ calculation. Additionally, we report the results on a dedicated study to shed light on the resonant states production in the energy region around 2.2 GeV, which is presently rather unclear. We measure the reaction $e^+e^-to K_SK_L$ with data collected with the $BABAR$ detector and analyse these data in conjunction with published BESIII data on $e^+e^-to K^+K^-$ and $BABAR$ data on $e^+e^-to K^+K^-$, $pi^+pi^-$, $pi^+pi^-eta$, $pi^+pi^-omega$. This study supports the existence of an isovector resonance $rho(2230)$ consistent with the resonance observed by BESIII.
We report results of experiments performed with the KEDR detector at the VEPP-4M e+e- collider. They include precise measurement of the D0 and D+- meson masses, determination of the psi(3770) resonance parameters, and a search for narrow resonances in e+e- annihilation at center-of-mass energies between 1.85 and 3.1 GeV.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
