40 research outputs found
Investigation of the high momentum component of nuclear wave function using hard quasielastic A(p,2p)X reactions
We present theoretical analysis of the first data on the high energy and
momentum transfer (hard) quasielastic reactions. The cross section
of hard reaction is calculated within the light-cone impulse
approximation based on two-nucleon correlation model for the high-momentum
component of the nuclear wave function. The nuclear effects due to modification
of the bound nucleon structure, soft nucleon-nucleon reinteraction in the
initial and final states of the reaction with and without color coherence have
been considered. The calculations including these nuclear effects show that the
distribution of the bound proton light-cone momentum fraction shifts
towards small values (), effect which was previously derived only
within plane wave impulse approximation. This shift is very sensitive to the
strength of the short range correlations in nuclei. Also calculated is an
excess of the total longitudinal momentum of outgoing protons. The calculations
are compared with data on the reaction obtained from the EVA/AGS
experiment at Brookhaven National Laboratory. These data show -shift in
agreement with the calculations. The comparison allows also to single out the
contribution from short-range nucleon correlations. The obtained strength of
the correlations is in agreement with the values previously obtained from
electroproduction reactions on nuclei.Comment: 30 pages LaTex file and 19 eps figure
K* nucleon hyperon form factors and nucleon strangeness
A crucial input for recent meson hyperon cloud model estimates of the nucleon
matrix element of the strangeness current are the nucleon-hyperon-K* (NYK*)
form factors which regularize some of the arising loops. Prompted by new and
forthcoming information on these form factors from hyperon-nucleon potential
models, we analyze the dependence of the loop model results for the
strange-quark observables on the NYK* form factors and couplings. We find, in
particular, that the now generally favored soft N-Lambda-K* form factors can
reduce the magnitude of the K* contributions in such models by more than an
order of magnitude, compared to previous results with hard form factors. We
also discuss some general implications of our results for hadronic loop models.Comment: 9 pages, 8 figures, new co-author, discussion extended to the
momentum dependence of the strange vector form factor
Super-conservative interpretation of muon g-2 results applied to supersymmetry
The recent developments in theory and experiment related to the anomalous
magnetic moment of the muon are applied to supersymmetry. We follow a very
cautious course, demanding that the supersymmetric contributions fit within
five standard deviations of the difference between experiment and the standard
model prediction. Arbitrarily small supersymmetric contributions are then
allowed, so no upper bounds on superpartner masses result. Nevertheless,
non-trivial exclusions are found. We characterize the substantial region of
parameter space ruled out by this analysis that has not been probed by any
previous experiment. We also discuss some implications of the results for
forthcoming collider experiments.Comment: 10 pages, latex, 3 fig
K^* Mesons and Nucleon Strangeness
We study contributions to the nucleon strange quark vector current form
factors from intermediate states containing K^* mesons. We show how these
contributions may be comparable in magnitude to those made by K mesons, using
methods complementary to those employed in quark model studies. We also analyze
the degree of theoretical uncertainty associated with K^* contributions.Comment: 21 pages, RevTex, 2 PS figures included with epsf.st
Physics Opportunities with the 12 GeV Upgrade at Jefferson Lab
This white paper summarizes the scientific opportunities for utilization of
the upgraded 12 GeV Continuous Electron Beam Accelerator Facility (CEBAF) and
associated experimental equipment at Jefferson Lab. It is based on the 52
proposals recommended for approval by the Jefferson Lab Program Advisory
Committee.The upgraded facility will enable a new experimental program with
substantial discovery potential to address important topics in nuclear,
hadronic, and electroweak physics.Comment: 64 page
Radiative processes (tau -> mu gamma, mu -> e gamma and muon g-2) as probes of ESSM/SO(10)
The Extended Supersymmetric Standard Model (ESSM), motivated on several
grounds, introduces two vectorlike families (16 + 16-bar) of SO(10)) with
masses of order one TeV. It is noted that the successful predictions of prior
work on fermion masses and mixings, based on MSSM embedded in SO(10), can be
retained rather simply within the ESSM extension. These include an
understanding of the smallness of V_{cb} ~ 0.04 and the largeness of nu_mu -
nu_tau oscillation angle, sin^2 2 theta_{nu_mu nu_tau}^{osc} ~ 1. We analyze
the new contributions arising through the exchange of the vectorlike families
of ESSM to radiative processes including tau -> mu gamma, mu -> e gamma, b -> s
gamma, EDM of the muon and the muon (g-2). We show that ESSM makes significant
contributions especially to the decays tau -> mu gamma and mu -> e gamma and
simultaneously to muon (g-2). For a large and plausible range of relevant
parameters, we obtain: a_mu^{ESSM} ~ +(10-40) times 10^{-10}, with a correlated
prediction that tau -> mu gamma should be discovered with an improvement in its
current limit by a factor of 3-20. The implications for mu -> e gamma are very
similar. The muon EDM is within reach of the next generation experiments. Thus,
ESSM with heavy leptons being lighter than about 700 GeV (say) can be probed
effectively by radiative processes before a direct search for these vectorlike
leptons and quarks is feasible at the LHC.Comment: 27 pages LaTex, 2 figure
Neutron and hard X-ray measurements during pellet deposition in TFTR
Measurements of neutrons and hard x rays are made with a pair of plastic scintillators during injection of deuterium pellets into deuterium TFTR plasmas. Three cases are investigated. During ohmic heating in plasmas with few runaway electrons, the neutron emission does not increase when a pellet is injected, indicating that strong acceleration of the pellet ions does not occur. In ohmic plasmas with low but detectable levels of runaway electrons, an x-ray burst is observed on a detector near the pellet injector as the pellet ablates, while a detector displaced 126/sup 0/ toroidally from the injector does not measure a synchronous burst. Reduced pellet penetration correlates with the presence of x-ray emission, suggesting that the origin of the burst is bremsstrahlung from runaway electrons that strike the solid pellet. In deuterium beam-heated discharges, an increase in the d-d neutron emission is observed when the pellet ablates. In this case, the increase is due to fusion reactions between beam ions and the high density neutral and plasma cloud produced by ablation of the pellet; this localized density perturbation equilibrates in about 700 ..mu..sec. Analysis of the data indicates that the density propagates without forming a sharp shock front with a rapid initial propagation velocity (greater than or equal to 2 x 10/sup 7/ cm/sec) that subsequently decreases to around 3 x 10/sup 6/ cm/sec. Modelling suggests that the electron heat flux into the pellet cloud is much less than the classical Spitzer value
A Novel Mitragynine Analog with Low-Efficacy Mu Opioid Receptor Agonism Displays Antinociception with Attenuated Adverse Effects
Mitragynine and 7-hydroxymitragynine (7OH) are the major alkaloids mediating the biological actions of the psychoactive plant kratom. To investigate the structure-activity relationships of mitragynine/7OH templates, we diversified the aromatic ring of the indole at the C9, C10, and C12 positions and investigated their G-protein and arrestin signaling mediated by mu opioid receptors (MOR). Three synthesized lead C9 analogs replacing the 9-OCH3group with phenyl (4), methyl (5), or 3âČ-furanyl [6(SC13)] substituents demonstrated partial agonism with a lower efficacy than DAMGO or morphine in heterologous G-protein assays and synaptic physiology. In assays limiting MOR reserve, the G-protein efficacy of all three was comparable to buprenorphine.6(SC13) showed MOR-dependent analgesia with potency similar to morphine without respiratory depression, hyperlocomotion, constipation, or place conditioning in mice. These results suggest the possibility of activating MOR minimally (G-proteinEmaxâ 10%) in cell lines while yet attaining maximal antinociceptionin vivowith reduced opioid liabilities
Interpreting the New Brookhaven g_mu - 2 Result
The latest g_mu - 2 measurement by Brookhaven confirms the earlier
measurement with twice the precision. However, interpretation of the result
requires specific assumptions regarding the errors in the hadronic light by
light (LbL) correction and in the hadronic vacuum polarization correction.
Under the assumption that the analysis on LbL correction of Knecht and Nyffeler
and the revised analysis of Hayakawa and Kinoshita are valid the new BNL result
implies a deviation between experiment and the standard model of 1.6 sigma -2.6
sigma depending on the estimate of the hadronic vacuum polarization correction.
We revisit the g_mu - 2 constraint for mSUGRA and its implications for the
direct detection of sparticles at colliders and for the search for
supersymmetric dark matter in view of the new evaluation.Comment: 15 pages, Latex including 3 figure