A5044120489- Quantum Chromodynamics and Particle Interactions
- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Nuclear physics research studies
- Atomic and Subatomic Physics Research
- Medical Imaging Techniques and Applications
- Radiation Detection and Scintillator Technologies
- Nuclear Physics and Applications
- Dark Matter and Cosmic Phenomena
- Particle Accelerators and Free-Electron Lasers
- Particle Detector Development and Performance
- Advanced NMR Techniques and Applications
- Atomic and Molecular Physics
- X-ray Spectroscopy and Fluorescence Analysis
- Quantum chaos and dynamical systems
- Black Holes and Theoretical Physics
- High-pressure geophysics and materials
- Rare-earth and actinide compounds
- Crystallography and Radiation Phenomena
- Neutrino Physics Research
- Advanced Frequency and Time Standards
- Inorganic Chemistry and Materials
- Advancements in PLL and VCO Technologies
- Thermodynamic and Structural Properties of Metals and Alloys
- Integrated Circuits and Semiconductor Failure Analysis
Florida State University
2023-2024
Thomas Jefferson National Accelerator Facility
2009-2022
North Carolina Agricultural and Technical State University
2009-2019
Leiden University
2008
Campbell Collaboration
2000-2007
University of America
2007
Catholic University of America
2007
Massachusetts Institute of Technology
2007
Justus-Liebig-Universität Gießen
2007
University of California, Los Angeles
2003-2007
In an exclusive measurement of the reaction gammad-->K(+)K(-)pn, a narrow peak that can be attributed to exotic baryon with strangeness S=+1 is seen in K(+)n invariant mass spectrum. The at 1.542+/-0.005 GeV/c(2) measured width 0.021 FWHM, which largely determined by experimental resolution. statistical significance (5.2+/-0.6)sigma. and observed are consistent recent reports other groups.
We report on the measurement of γp→J/ψp cross section from E_{γ}=11.8 GeV down to threshold at 8.2 using a tagged photon beam with GlueX experiment. find that total falls toward less steeply than expected two-gluon exchange models. The differential dσ/dt has an exponential slope 1.67±0.39 GeV^{-2} 10.7 average energy. LHCb pentaquark candidates P_{c}^{+} can be produced in s channel this reaction. see no evidence for them and set model-dependent upper limits their branching fractions...
We report the first results of beam-spin asymmetry measured in reaction $\stackrel{\ensuremath{\rightarrow}}{e}p\ensuremath{\rightarrow}\mathrm{ep}\ensuremath{\gamma}$ at a beam energy 4.25 GeV. A large with $\mathrm{sin}\ensuremath{\varphi}$ modulation is observed, as predicted for interference term deeply virtual compton scattering (DVCS) and Bethe-Heitler process. The amplitude this...
The ratios of inclusive electron scattering cross sections 4He, 12C, and 56Fe to 3He have been measured at 1<xB<3. At Q2>1.4 GeV2, the exhibit two separate plateaus, 1.5<xB<2 xB>2.25. This pattern is predicted by models that include 2- 3-nucleon short-range correlations (SRC). Relative A=3, per-nucleon probabilities SRC are 2.3, 3.1, 4.4 times larger for A=4, 12, 56. first measurement in nuclei.Received 16 August 2005DOI:https://doi.org/10.1103/PhysRevLett.96.082501©2006 American Physical Society
The reaction gamma p-->pi(+)K(-)K(+)n was studied at Jefferson Laboratory using a tagged photon beam with an energy range of 3-5.47 GeV. A narrow baryon state strangeness S=+1 and mass M=1555+/-10 MeV/c(2) observed in the nK(+) invariant spectrum. peak's width is consistent CLAS resolution (FWHM=26 MeV/c(2)), its statistical significance (7.8+/-1.0)sigma. positive has exotic structure cannot be described framework naive constituent quark model. predicted by chiral soliton model for Theta(+)...
Models of baryon structure predict a small quadrupole deformation the nucleon due to residual tensor forces between quarks or distortions from pion cloud. Sensitivity quark versus degrees freedom occurs through Q2 dependence magnetic (M1+), electric (E1+), and scalar (S1+) multipoles in gamma*p-->Delta(+)-->p pi(0) transition. We report new experimental values for ratios E(1+)/M(1+) S(1+)/M(1+) over range = 0.4-1.8 GeV2, extracted precision p(e,e(')p)pi(0) data using truncated multipole...
The beam-spin asymmetries in the hard exclusive electroproduction of photons on proton ($\stackrel{\ensuremath{\rightarrow}}{e}p\ensuremath{\rightarrow}ep\ensuremath{\gamma}$) were measured over a wide kinematic range and with high statistical accuracy. These result from interference Bethe-Heitler process deeply virtual Compton scattering. Over whole (${x}_{B}$ 0.11 to 0.58, ${Q}^{2}$ 1 $4.8\text{ }\text{ }{\mathrm{GeV}}^{2}$, $\ensuremath{-}t$ 0.09 $1.8\text{ }{\mathrm{GeV}}^{2}$),...
Cross-sections and recoil polarizations for the reactions gamma + p --> K^+ Lambda Sigma^0 have been measured with high statistics good angular coverage center-of-mass energies between 1.6 2.3 GeV. In K^+Lambda channel we confirm a structure near W=1.9 GeV at backward kaon angles, but our data shows more complex s- u- resonance than previously seen. This is present forward angles not central its position width change angle, indicating that one playing role. Rising back-angle cross sections...
We report the total and differential cross sections for $J/\psi$ photoproduction with large acceptance GlueX spectrometer photon beam energies from threshold at 8.2~GeV up to 11.44~GeV over full kinematic range of momentum transfer squared, $t$. Such coverage facilitates extrapolation forward ($t = 0$) point beyond physical region. The section is used by many theoretical models plays an important role in understanding its relation $J/\psi-$proton interaction. These measurements near are also...
The ratios of inclusive electron scattering cross sections $^4$He, $^{12}$C, and $^{56}$Fe to $^3$He have been measured for the first time. It is shown that these are independent $x_B$ at Q$^2>$1.4 (GeV/c)$^2$ $x_B>$ 1.5 where section depends primarily on high-momentum components nuclear wave function. observed scaling shows momentum distributions high-momenta same shape all nuclei differ only by a scale factor. onset $x_B >$1.5 consistent with kinematical expectation two nucleon short range...
We report the first evidence for a nonzero beam-spin azimuthal asymmetry in electroproduction of positive pions deep-inelastic kinematic region. Data reaction $e\stackrel{\ensuremath{\rightarrow}}{p}{e}^{\ensuremath{'}}{\ensuremath{\pi}}^{+}X$ have been obtained using polarized electron beam 4.3 GeV with CEBAF Large Acceptance Spectrometer at Thomas Jefferson National Accelerator Facility. The amplitude $\mathrm{sin}\ensuremath{\varphi}$ modulation increases momentum pion relative to virtual...
High precision measurements of the differential cross sections for π0 photoproduction at forward angles two nuclei, 12C and 208Pb, have been performed incident photon energies 4.9-5.5 GeV to extract π0→γγ decay width. The experiment was done Jefferson Lab using Hall B tagger a high-resolution multichannel calorimeter. width extracted by fitting measured recently updated theoretical models process. resulting value is Γ(π0→γγ)=7.82±0.14(stat)±0.17(syst) eV. With 2.8% total uncertainty, this...
Differential cross sections for gammap-->etap have been measured with tagged real photons incident photon energies from 0.75 to 1.95 GeV. Mesons were identified by missing mass reconstruction using kinematical information protons scattered in the production process. The data provide first extensive angular distribution measurements process above W=1.75 Comparison preliminary results a constituent quark model support suggestion that third S11 resonance approximately 1.8 GeV couples etaN channel.
The cross section for the reaction ep-->e(')ppi(+)pi(-) was measured in resonance region 1.4<W<2.1 GeV and 0.5<Q2<1.5 GeV(2)/c(2) using CLAS detector at Jefferson Laboratory. data show resonant structures not visible previous experiments. comparison of our to a phenomenological prediction available information on N(*) Delta states shows an evident discrepancy. A better description is obtained either by sizable change properties P13(1720) or introducing new baryon state, reported published analyses.
New cross sections for the reaction e p-->e p eta are reported total center of mass energy W = 1.5--1.86 GeV and invariant momentum transfer Q2 0.25--1.5 (GeV/c)(2). This large kinematic range allows extraction important new information about response functions, photocouplings, N coupling strengths baryon resonances. Newly observed structure at approximately 1.65 is shown to come from interference between S P waves can be interpreted with known Improved values derived photon amplitude...
We report a new measurement of the exclusive electroproduction reaction ${\ensuremath{\gamma}}^{*}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}p$ to explore evolution from soft nonperturbative physics hard processes via ${Q}^{2}$ dependence magnetic (${M}_{1+}$), electric (${E}_{1+}$), and scalar (${S}_{1+}$) multipoles in $N\ensuremath{\rightarrow}\ensuremath{\Delta}$ transition. 9000 differential cross section data points cover $W$ threshold $1.4\text{ }\text{ }\mathrm{GeV}/{c}^{2}$,...
A search for the Θ+ in reaction γd→pK−K+n was completed using CLAS detector at Jefferson Lab. study of same reaction, published earlier, reported observation a narrow resonance. The present experiment, with more than 30 times integrated luminosity our earlier measurement, does not show any evidence pentaquark angle-integrated upper limit on production mass range 1.52–1.56 GeV/c2 γd→pK−Θ+ is 0.3 nb (95% C.L.). This depends assumptions made and angular distribution production. Using Λ(1520) as...
We report measurements of the photon beam asymmetry $\Sigma$ for reactions $\vec{\gamma}p\to p\pi^0$ and p\eta $ from GlueX experiment using a 9 GeV linearly-polarized, tagged incident on liquid hydrogen target in Jefferson Lab's Hall D. The asymmetries, measured as function proton momentum transfer, possess greater precision than previous $\pi^0$ are first $\eta$ this energy regime. results compared with theoretical predictions based $t$-channel, quasi-particle exchange constrain...
The GlueX experiment at Jefferson Lab ran with its first commissioning beam in late 2014 and the spring of 2015. Data were collected on both plastic liquid hydrogen targets, much detector has been commissioned. All systems are now performing or near design specifications events being fully reconstructed, including exclusive production π0, η ω mesons. Linearly-polarized photons successfully produced through coherent bremsstrahlung polarization transfer to ρ observed.
We measure for the first time differential photoproduction cross section $d\sigma/dt$ of $a_2(1320)$ meson at an average photon beam energy 8.5~GeV, using data with integrated luminosity 104~pb$^{-1}$ collected by GlueX experiment. fully reconstruct $\gamma p \to \eta\pi^0 p$ reaction and perform a partial-wave analysis in mass region amplitudes that incorporate linear polarization beam. This allows us to separate contributions natural- unnatural-parity exchanges. These measurements provide...
The exclusive reaction gammap-->K0K+n was studied in the photon energy range between 1.6 and 3.8 GeV searching for evidence of exotic baryon Theta+ (1540)-->nK+. decay to nK+requires assignment strangeness S=+1 any observed resonance. Data were collected with CLAS detector at Thomas Jefferson National Accelerator Facility corresponding an integrated luminosity 70 pb-1. No pentaquark found. Upper limits set on production cross section as function center-of-mass angle nK+ mass. 95% C.L. upper...
The explicit breaking of the axial symmetry by quantum fluctuations gives rise to so-called anomaly. This phenomenon is solely responsible for decay neutral pion π0 into two photons (γγ), leading its unusually short lifetime. We precisely measured width Γ [Formula: see text] process. differential cross sections photoproduction at forward angles were on targets, carbon-12 and silicon-28, yielding text], where stat. denotes statistical uncertainty syst. systematic uncertainty. combined results...