Showing papers by "Hyun-Chul Kim published in 1995"

Observation of top quark production in p̄p collisions with the collider detector at fermilab

Abstract: We establish the existence of the top quark using a $67{\mathrm{pb}}^{\ensuremath{-}1}$ data sample of $\overline{p}p$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$ collected with the Collider Detector at Fermilab (CDF). Employing techniques similar to those we previously published, we observe a signal consistent with $t\overline{t}$ decay to $\mathrm{WWb}\overline{b}$, but inconsistent with the background prediction by $4.8\ensuremath{\sigma}$. Additional evidence for the top quark is provided by a peak in the reconstructed mass distribution. We measure the top quark mass to be $176\ifmmode\pm\else\textpm\fi{}8(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}10(\mathrm{syst})\mathrm{GeV}{/c}^{2}$, and the $t\overline{t}$ production cross section to be ${6.8}_{\ensuremath{-}2.4}^{+3.6}\mathrm{pb}$.

Search for New Gauge Bosons Decaying into Dileptons in p̄p Collisions at s} = 1.8 TeV

Abstract: We have searched for heavy neutral gauge bosons (2’) in jjp collisions at Js = 1.8 TeV. The data were obtained using the CDF detector during 19921993 run corresponding to an integrated luminosity of 19.7f0.7 pb-‘. We present a 95% confidence level upper limit on the production cross section times branching ratio of 2’ decaying into dielectrons as a function of 2’ mass. Assuming Standard Model coupling strengths, we exclude a 2’ with mass less than 505 GeV/c 2. We also present lower mass limits for 2’ bosons from & models and the Alternative Left-Right Model. PACS numbers: 13.85.Rm, 12.15.Cc, 14.80.Er Neutral gauge bosons in addition to the 2’ are expected in many extensions of the Standard Model [l]. These models typically specify the strengths of the couplings of such bosons to quarks and leptons but make no mass predictions [2]. In up collisions, 2’ bosons may be observed directly via their decay to lepton pairs. Observation of a 2’ boson would provide dramatic evidence for physics beyond the Standard Model. To date there is no experimental evidence for the existence of any 2’ [3]. The current experimental 2’ mass limit Mzt > 412 GeV/c2 (95% C.L.) was established by the CDF collaboration [4] with the assumption that the coupling strengths of the 2’ to quarks and leptons were the same as those for the Standard Model (SM) 2’. This result was based upon data collected during the 1988-89 run with an integrated luminosity of 4 pb-’ and used both the dielectron [5] and dimuon decay modes. We report an extension of this search using 19.7 pb* of integrated luminosity from the 1992-93 run. Results reported here are obtained using only the dielectron decay mode. We present a 95% confidence level upper limit on the production cross section times branching ratio of 2’ decaying into dielectrons (g(Z) . B(Z’ + ee)). Mass limits are 5 again derived assuming SM coupling strengths. In addition, we present 2’ mass limits using several different theoretical models based on the Es symmetry group [6][‘7] and one limit based upon an Alternative Left-Right Model [8]. The CDF detector has been described in detail elsewhere [9]. We give a brief description of the components relevant to this analysis. Momenta of charged particles are measured in the Central Tracking Chamber (CTC), which is immersed in a 1.4 T axial magnetic field. Outside the CTC, electromagnetic and hadronic calorimeters are arranged in a projective tower geometry. There are three separate pseudorapidity (7) regions of calorimeters, central, end-plug, and forward, where 7 = ln(tan $) and 0 is the polar angle with respect to the direction of the proton beam. Each region has an electromagnetic calorimeter and behind it a hadronic calorimeter. For this analysis we use electrons detected in the central (CEM) or end-plug (PEM) regions. The CEM covers ]q] 9 GeV or an energy cluster in the PEM with ET > 20 GeV. If the cluster was in the CEM the trigger also required a coincidence with a track of transverse momentum PT > 9.2 GeV/c. In addition, the trigger required that the ratio of hadronic to electromagnetic energy (HAD/EM) in the trigger cluster be less than 12.5%. For electrons with 25 150 GeV), the energy deposited

Measurement of the B meson differential cross section dσ/dpT in pp̄ collisions at s = 1.8 TeV

Abstract: This paper presents the first direct measurement of the $B$ meson differential cross section $d\ensuremath{\sigma}{/dp}_{T}$ in $p\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8$ TeV using a sample of $19.3\ifmmode\pm\else\textpm\fi{}0.7$ p${\mathrm{b}}^{--1}$ accumulated by the Collider Detector at Fermilab. The cross section is measured in the central rapidity region $|y|l1$ for ${p}_{T}\left(B\right)g6.0$ GeV $/c$ by fully reconstructing the $B$ meson decays ${B}^{+}\ensuremath{\rightarrow}J/\ensuremath{\psi}{K}^{+}$ and ${B}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}{K}^{*0}\left(892\right)$, where $J/\ensuremath{\psi}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and ${K}^{*0}\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$. A comparison is made to the theoretical QCD prediction calculated at next-to-leading order.

An electron‐beam microcolumn with improved resolution, beam current, and stability

Abstract: We have built and tested a 1 keV electron‐beam microcolumn that focuses 1 nA of beam current into a 10 nm full width half‐maximum beam diameter at a working distance of 1 mm. The electron source is a miniaturized Zr/O/W Schottky field emitter with 150 μA/sr angular emission current density operating at about 1800 K at a distance of only 100 μm from a silicon membrane extractor electrode. The actual microcolumn is 3.5 mm long assembled mainly from silicon membrane electrodes. Improved einzel lens design and fabrication allowed the operation of this beam focusing element in the accelerating mode. Spherical and chromatic aberrations were reduced by factors of about 2–3, respectively, as compared to the retarding lens mode. Excellent beam current stability with less than 1% variation over several hours has been observed.

Search for New Particles Decaying to Dijets in pp̄ Collisions at √s = 1.8 TeV

Abstract: We have used 19 pb**-1 of data collected with the Collider Detector at Fermilab to search for new particles decaying to dijets. We exclude at 95% confidence level models containing the following new particles: axigluons with mass between 200 and 870 GeV, excited quarks with mass between 80 and 570 GeV, and color octet technirhos with mass between 320 and 480 GeV.

Measurement of W-photon couplings in p- p collisions at s=1.8 TeV

Abstract: We report on a study of [ital W]+ photon production in approximately 20 pb[sup [minus]1] of [ital p][minus][ital [bar p]] collisions at [radical][ital s]=1.8 TeV recorded with the Collider Detector at Fermilab. Our results are in good agreement with standard model expectations and are used to obtain limits on anomalous [ital CP]-conserving [ital WW][gamma] couplings of [minus]2.3[lt][Delta][kappa][lt]2.2 for [lambda]=0 and [minus]0.7[lt][lambda][lt]0.7 for [Delta][kappa]=0 at 95% C.L. We obtain the same limits for [ital CP]-violating couplings. These results provide limits on the higher-order electromagnetic moments of the [ital W] boson of 0.8[lt][ital g][sub [ital W]][lt]3.1 for [ital q][sup [ital e]][sub [ital W]]=1 and [minus]0.6[lt][ital q][sup [ital e]][sub [ital W]][lt]2.7 for [ital g][sub [ital W]]=2 at 95% C.L.

Correlated $\pi\pi$ and $K\bar K$ exchange in the baryon-baryon interaction

Abstract: A dynamical model for correlated two-pion and two-kaon exchange in the baryon- baryon interaction is presented, both in the scalar-isoscalar ($\sigma$) and the vector-isovector ($\rho$) channel. The correlations between the two pseudoscalar mesons are taken into account by means of $\pi\pi - K\bar K$ amplitudes derived from a meson-exchange model, which is in line with the empirical $\pi\pi$ data. It is found that correlated $K\bar K$ exchange plays an important role in the $\sigma$-channel for baryon-baryon states with non- vanishing strangeness. The strength of correlated $\pi\pi$ plus $K\bar K$ exchange in the $\sigma$-channel decreases with the strangeness of the baryon- baryon system becoming more negative. The results for correlated $\pi\pi$- exchange in the vector-isovector channel deviate from what is expected in the naive SU(3) picture for genuine $\rho$-exchange. Shortcomings of a simplified description in terms of sharp mass $\sigma$- and $\rho$-exchange are pointed out.

Charge Asymmetry in W-Boson Decays Produced in pp¯ Collisions at s=1.8 TeV

Abstract: Charge asymmetry has been measured using 19 039 [ital W] decays recorded by the Collider Detector at Fermilab during the 1992--93 run of the Tevatron Collider. The asymmetry is sensitive to the ratio of [ital d] and [ital u] quark distributions to [ital x][lt]0.01 at [ital Q][sup 2][approx][ital M][sup 2][sub [ital W]], where nonperturbative effects are minimal. It is found that of the two current sets of parton distributions, those of Martin, Roberts, and Stirling are favored over the sets most recently produced by the CTEQ Collaboration. The [ital W] asymmetry data provide stronger constraints on [ital d]/[ital u] ratio than the recent measurements of [ital F][sub 2][sup [mu][ital n]]/[ital F][sub 2][sup [mu][ital p]], which are limited by uncertainties originating from deuteron corrections.

Miniature Schottky electron source

Abstract: A miniature Schottky electron source has been developed and evaluated for applications in a new generation of scanning tunneling microscope aligned field emission microcolumns. Both the physical dimensions and the heating power of this source have been significantly reduced from a conventional source of the same kind. Operating parameters for such a source in a microcolumn environment in terms of emission characteristics, suppressor operating range, etc., have been evaluated. Test results show that very good emission stability at ≥100 μA emission current over several hours, and axial angular current densities in excess of 100 μA/sr can be obtained. Energy distributions have been measured using a carefully calibrated analyzer, and the results show a full width at half‐maximum of 0.4 to 0.76 eV for a 0.3 μm radius Schottky source operating over an angular current density range of 1 to over 100 μA/sr. A significant change in the shape of the energy distribution was observed over this range of operation, indi...

Search for charged bosons heavier than the W boson in pp̄ collisions at s=1800 GeV

Abstract: We have searched for new, heavy, charged bosons {ital W}{prime} through the decay {ital W}{prime}{r_arrow}{ital e}{nu} in {ital pp}{ovr bar} collisions at {radical}{ital s}=1.8 TeV. The data used in the search represent 19.7 pb{sup --1}collected by the Collider Detector at Fermilab. Limits are placed on {sigma}{ital B}({ital pp}{ovr bar}{r_arrow}{ital W}{prime}{r_arrow}{ital e}{nu}) as a function of {ital M}{sub {ital W}{prime}}. Assuming standard couplings of the {ital W}{prime} to fermions, we establish the limit {ital M}{sub {ital W}{prime}}{gt}652 GeV/{ital c}{sup 2} (95% C.L.).

Limits on Z-photon couplings from p- p interactions at s=1.8 TeV

Abstract: We report limits on anomalous [ital ZZ][gamma] and [ital Z][gamma][gamma] couplings derived from an analysis of [ital Z]+photon production based upon approximately 20pb[sup [minus]1] of the [bar p] collision data recorded by the Collider Detector at Fermilab. We observe good agreement with the standard model expectation that all [ital Z][gamma] couplings are zero. Confidence level intervals for individual couplings and contours for pairs of [ital CP]-conserving/violating [ital ZZ][gamma] and [ital Z][gamma][gamma] couplings are presented.

Measurement of the Polarization in the Decays Bd → J/ψ K*0 and Bs → J/ψ φ

Abstract: This Letter reports on measurements of the longitudinal polarization fractions in the decays {ital B}{sub {ital d}}{r_arrow}{ital J}/{psi}{ital K}{sup *0} and {ital B}{sub {ital s}}{r_arrow}{ital J}/{psi}{phi} using data collected with the Collider Detector at Fermilab. {ital B}{sub {ital d}} mesons are reconstructed through the decay chain {ital B}{sub {ital d}}{r_arrow}{ital J}/{psi}{ital K}*, {ital J}/{psi}{r_arrow}{mu}{sup +}{mu}{sup {minus}}, {ital K}{sup *0}{r_arrow}{ital K}{sup +}{pi}{sup {minus}}. A sample of 65{plus_minus}10{ital B}{sub {ital d}} events is used to obtain a longitudinal polarization fraction of {Gamma}{sub {ital L}}/{Gamma}=0.65{plus_minus}0.10(stat){plus_minus}0.04(syst). {ital B}{sub {ital s}} mesons are reconstructed through the decay chain {ital B}{sub {ital s}}{r_arrow}{ital J}/{psi}{phi}, {ital J}/{psi}{r_arrow}{mu}{sup +}{mu}{sup {minus}}, {phi}{r_arrow}{ital K}{sup +}{ital K}{sup {minus}}. A sample of 19{plus_minus}5{ital B}{sub {ital s}} events is used to obtain the result {Gamma}{sub {ital L}}/{Gamma}=0.56{plus_minus}0.21(stat){sub {minus}0.04}{sup +0.02}(syst). Copyright {ital 1995} {ital The} {ital American} {ital Physical} {ital Society}.

Search for second generation leptoquarks in pp collisions at s=1.8 TeV

Abstract: We present the results of a search for second generation leptoquarks ${S}_{2}$ using $19.3{\mathrm{pb}}^{\ensuremath{-}1}$ of data collected at the Collider Detector at Fermilab (CDF) in $p\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8$ TeV during the 1992--93 collider run. We have searched for ${S}_{2}\overline{{S}_{2}}$ pairs assuming that each leptoquark decays to a muon $+$ quark with a branching ratio $\ensuremath{\beta}$. We find two candidate events, consistent with an expected background of $1.11\ifmmode\pm\else\textpm\fi{}0.48$. We obtain upper limits on $\ensuremath{\sigma}(p\overline{p}\ensuremath{\rightarrow}{S}_{2}\overline{{S}_{2}}){\ensuremath{\beta}}^{2}$ as a function of ${M}_{{S}_{2}}$. Using a Monte Carlo prediction for ${S}_{2}\overline{{S}_{2}}$ pair production, we exclude ${M}_{{S}_{2}}l131\phantom{\rule{0ex}{0ex}}\mathrm{GeV}/{c}^{2}$ for $\ensuremath{\beta}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1$ and ${M}_{{S}_{2}}l96\phantom{\rule{0ex}{0ex}}\mathrm{GeV}/{c}^{2}$ for $\ensuremath{\beta}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.5$ at 95% C.L.

Further properties of high-mass multijet events at the Fermilab proton-antiproton collider

Abstract: The properties of high-mass multijet events produced at the Fermilab proton-antiproton collider are compared with leading order QCD matrix element predictions, QCD parton shower Monte Carlo predictions, and the predictions from a model in which events are distributed uniformly over the available multibody phase space. Multijet distributions corresponding to (4{ital N}{minus}4) variables that span the {ital N}-body parameter space are found to be well described by the QCD calculations for inclusive three-jet, four-jet, and five-jet events. The agreement between data, QCD matrix element calculations, and QCD parton shower Monte Carlo predictions suggests that 2{r_arrow}2 scattering plus gluon radiation provides a good first approximation to the full LO QCD matrix element for events with three, four, or even five jets in the final state. {copyright} {ital 1996 The American Physical Society.}

Measurement of the Bs meson lifetime.

Abstract: The lifetime of the {ital B}{sub {ital s}} meson is measured using the semileptonic decay {ital B}{sub {ital s}}{r_arrow}{ital D}{sub {ital s}}{sup {minus}}l{sup +}{nu}{ital X}. The data sample consists of 19.3 pb{sup {minus}1} of {ital p{bar p}} collisions at {radical}{ital s}=1.8 TeV collected by the Collider Detector at Fermilab during 1992--1993. There are 76{plus_minus}8 l{sup +}{ital D}{sub {ital s}}{sup {minus}} signal events where the {ital D}{sub {ital s}} is identified via the decay {ital D}{sub {ital s}}{sup {minus}}{r_arrow}{phi}{pi}{sup {minus}}, {phi}{r_arrow}{ital K}{sup +}{ital K}{sup {minus}}. Using these events, the {ital B}{sub {ital s}} meson lifetime is determined to be {tau}{sub {ital s}}=1.42{sub {minus}0.23}{sup +0.27}(stat){plus_minus}0.11(syst) ps. A measurement of the {ital B}{sub {ital s}} lifetime in a low statistics sample of exclusive {ital B}{sub {ital s}}{r_arrow}{ital J}/{psi}{phi} decays is also presented in this paper.

Electron-beam microcolumn technology and applications

Abstract: A fully functional electron beam microcolumn, 3.5 mm in length, demonstrating a probe size of 10 nm and beam current >= 1 nA at 1 keV has been successfully developed. This paper presents its current status and future directions. Potential applications ranging from low cost scanning electron microscopy to arrays of such microcolumns for lithography, metrology, testing etc. will be discussed.

Study of tt production in pp collisions using total transverse energy

Abstract: We analyze a sample of {ital W}+jet events collected with the Collider Detector at Fermilab (CDF) in {ital pp} collisions at {radical}{ital s}=1.8 TeV to study {ital tt} production. We employ a simple kinematical variable H, defined as the scalar sum of the transverse energies of the lepton, neutrino, and jets. For events with a {ital W} boson and four or more jets, the shape of the H distribution deviates by 3.8 standard deviations from that expected from known backgrounds to {ital tt} production. However, this distribution agrees well with a linear combination of background and {ital tt} events, the agreement being best for a top mass of 180 GeV/{ital c}{sup 2}. {copyright} {ital 1995} {ital The} {ital American} {ital Physical} {ital Society}.

Performance evaluation of reservation protocol with priority control for single-hop WDM networks

Abstract: A multipriority reservation protocol for the single-hop WDM network is proposed. The protocol is based on the passive star topology with control channel. Its performance is analysed for the case of two-priority traffic.

Measurement of the lifetime of the B-s(0) meson using the exclusive decay mode B-s(0)->J/psi phi

Abstract: The lifetime of the ${B}_{s}^{0}$ meson is measured using the exclusive decay mode ${B}_{s}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\varphi}$, where $J/\ensuremath{\psi}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and $\ensuremath{\varphi}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}$. The data sample consists of $110{\mathrm{pb}}^{\ensuremath{-}1}$ of $p\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\phantom{\rule{0ex}{0ex}}\mathrm{TeV}$, collected by the CDF detector at the Fermilab Tevatron collider during 1992--1995. We find $58\ifmmode\pm\else\textpm\fi{}12$ signal events, and the ${B}_{s}^{0}$ meson lifetime is determined to be ${\ensuremath{\tau}}_{{B}_{s}^{0}}{\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.34}_{\ensuremath{-}0.19}^{+0.23}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.05(\mathrm{syst})$ ps. This result is consistent with previous measurements of the ${B}_{s}^{0}$, ${B}^{+}$, and ${B}_{d}^{0}$ meson lifetimes and with theoretical predictions.

Map dynamic ranges versus duration of hearing loss in cochlear implantees.

Abstract: In order to assess the relationship of factors such as age, cause of deafness, use of hearing aids, duration of hearing loss, and age at onset of hearing loss, with the size of map dynamic ranges (DRs), 34 postlingually and 8 prelingually deaf users of the Nucleus cochlear implant system were analyzed according to the sizes of map DRs. Lack of auditory stimulation for a longer period than 10 years might be one of the most important factors associated with a reduced map DR. Use of hearing aids was associated with larger map DRs. Small map DRs were found across a range of age, age at onset, and duration of hearing loss. Cause of deafness did not appear to be related to map DRs.

Nd3+:ethylene glycol amplifier and its stimulated emission cross section

Abstract: We demonstrate that Nd3+:ethylene glycol can be used as an amplifier gain medium for a Nd3+:YLF laser. It has been known that Nd3+:liquid is hard to use as a gain medium due to fluorescence quenching. However, we could use Nd3+:ethylene glycol as a gain medium by using a new amplification system, and we also measured the stimulated emission cross section of Nd3+:ethylene glycol. A maximum gain of ∼2 was obtained in our experimental setup, and the stimulated emission cross section of Nd3+:ethylene glycol was measured to be 1.5(±0.5) ×10−19 cm2.

Electron gun for large-sized colour cathode ray tube

Abstract: An electron gun for a large-sized color cathode ray tube has three cathodes heated by a heater for emitting thermoelectrons, a first grid for controlling emitted electron beams on one side of the cathodes, a second grid for attracting the thermoelectrons gathered on the cathodes on one side of the first grid, a plurality of electrodes sequentially arranged on the second grid for accelerating and focusing the incoming electron beams, and a bead glass for fixing the electrodes spaced apart by predetermined distances, in which the thickness of the second grid is varied to decrease the divergence angle of the electron beams, and horizontal slits being rotary asymmetrical portions are formed in both sides around electron beam passing holes to contrive quadrupole effect, thereby compensating for distortion of the electron beams on the periphery of a screen caused by a deflection aberration to thus improve resolution of large-sized Brawn tubes.

Nucleon tensor charges in the chiral quark - soliton model

Abstract: We investigate the singlet g (0) T and isovector g (3) T tensor charges of the nucleon, which are deeply related to the first moment of the leading twist transversity quark distribution h 1 (x), in the chiral quark-soliton model. With rotational O(1/N c) corrections taken into account, we obtain g (0) T = 0.69 and g (3) T = 1.45 at a low normalization poin of several hundreds MeV. Within the same approximation and parameters the model yields g A = 1.21 for axial charges and correct octet–decuplet mass splitting. We show how the chiral quark-soliton model interpolates between the nonrelativistic quark model and the Skyrme model. The nucleon tensor charges are defined as a nucleon forward matrix element [1] N| ¯ ψ f σ µν ψ f |N = g f T ¯ U σ µν U, (1) where U(p) is a standard Dirac spinor and σ µν = i 2 [γ µ , γ ν ] in notation of Bjorken and Drell [2]. The tensor charges, as shown by Jaffe and Ji [1], are related to the first moment of the transversity quark distribution h 1 (x): 1 0 dx(h 1 (x) − ¯ h 1 (x)) = g f T , (2) where f is a flavor index (f = u, d, s, · · ·). Our aim is to calculate the tensor charges (1) in the chiral quark–soliton model (χQSM, often called the semibosonized Nambu—Jona-Lasinio model) at a low normalization point of several hundreds MeV. The χQSM has been successful in reproducing the static properties of the baryons such as the octet-decuplet mass splitting [3, 4], axial charges[5, 6, 7] and electro.m. form factors [8, 9]. The baryon in this model is regarded as a bound state of N c quarks bound by a non-trivial chiral field configuration. Such a semiclassical picture of baryons can be justified in the N c → ∞ limit in line with more general arguments by Witten [10]. A remarkable virtue of χQSM is that the model interpolates between the nonrelativistic quark model(NRQM) and the Skyrme model [11]. In particular, due to such an interplay, it enables us to examine the dynamical difference between the axial and tensor charges of the nucleon.

Update of the stranger story: The strange vector form factors of the nucleon in the SU(3) chiral quark-soliton model

Abstract: The strange vector form factors are evaluated for $Q^2=0$ and $Q^2=1\ \mbox{GeV}^2$ in the framework of the SU(3) chiral quark-soliton model (or semi-bosonized SU(3) Nambu-Jona-Lasinio model). The rotational $1/N_c$ and $m_s$ corrections are taken into account up to linear order. The mean-square strange radius $\langle r^{2}\rangle^{Sachs}_{s}=-0.35\; \mbox{fm}^2$ and the strange magnetic moment $\mu_s = -0.44\;\mu_N$ are obtained. The results are compared with several different models.

Strangeness in the Scalar Form Factor of the Nucleon

Abstract: The scalar form factor of the nucleon and related physical quantities are investigated in the framework of the semibosonized SU(3) Nambu-Jona-Lasinio soliton model. We take into account the rotational $1/N_c$ corrections and linear $m_s$ corrections. The strangeness content of the nucleon in the scalar form factor is discussed in detail. In particular, it is found that the $m_s$ corrections play an essential role of reducing the $\langle N | \bar{s} s | N \rangle$ arising from the leading order and rotational $1/N_c$ contributions. We obtain the $\sigma_{\pi N} (0)=40.80\;\mbox{MeV}$, $\Delta \sigma = \sigma_{\pi N} (2m^{2}_{\pi})-\sigma_{\pi N} (0) = 18.18\;\mbox{MeV}$ and $\langle r^2\rangle^{S}_{N} = 1.50\;\mbox{fm}^2$. The results are in a remarkable agreement with empirical data analyzed by Gasser, Leutwyler, and Sainio~\cite{gls}.