J. Richman
A5063169543- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Quantum Chromodynamics and Particle Interactions
- Particle Detector Development and Performance
- Dark Matter and Cosmic Phenomena
- Computational Physics and Python Applications
- Neutrino Physics Research
- Cosmology and Gravitation Theories
- Medical Imaging Techniques and Applications
- Particle Accelerators and Free-Electron Lasers
- Astrophysics and Cosmic Phenomena
- Black Holes and Theoretical Physics
- Radiation Detection and Scintillator Technologies
- Atomic and Subatomic Physics Research
- Distributed and Parallel Computing Systems
- Superconducting Materials and Applications
- Nuclear physics research studies
- Gamma-ray bursts and supernovae
- International Science and Diplomacy
- Nuclear Physics and Applications
- Radiation Effects in Electronics
- Stochastic processes and financial applications
- Noncommutative and Quantum Gravity Theories
- Nuclear reactor physics and engineering
- Advanced Data Storage Technologies
University of California, Santa Barbara
2016-2025
University of California System
2024-2025
A. Alikhanyan National Laboratory
2022-2024
University of Antwerp
2024
Institute of High Energy Physics
2013-2024
Massachusetts Institute of Technology
2021
Fermi National Accelerator Laboratory
2017
Campbell Collaboration
2013
University of California, Santa Cruz
2010
University of Birmingham
2009
Searches for lepton-flavor-violating decays of a tau lepton to lighter mass and photon have been performed with the entire data set (963+/-7)x10{6} collected by BABAR detector near Upsilon(4S), Upsilon(3S) Upsilon(2S) resonances. The searches yield no evidence signals we upper limits on branching fractions B(tau{+/-}-->e{+/-}gamma)<3.3x10{-8} B(tau{+/-}-->mu{+/-}gamma)<4.4x10{-8} at 90% confidence level.
Using the CLEO II detector, we have measured differential cross sections for exclusive two-photon production of light pseudoscalar mesons ${\ensuremath{\pi}}^{0},$ \ensuremath{\eta}, and ${\ensuremath{\eta}}^{\ensuremath{'}}.$ From our measurements obtained form factors associated with electromagnetic transitions ${\ensuremath{\gamma}}^{*}\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}}\mathrm{meson}.$ We these in momentum transfer ranges from 1.5 to 9, 20, $30{\mathrm{GeV}}^{2}$...
Dark sectors charged under a new Abelian interaction have recently received much attention in the context of dark matter models. These models introduce light mediator, so-called photon (A′), connecting sector to standard model. We present search for reaction e+e−→γA′, A′→e+e−, μ+μ− using 514 fb−1 data collected with BABAR detector. observe no statistically significant deviations from model predictions, and we set 90% confidence level upper limits on mixing strength between at 10−4−10−3...
A precise measurement of the cross section process e+ e- to pi+ pi- (gamma) from threshold an energy 3 GeV is obtained with initial state radiation (ISR) method using 232 fb^-1 data collected BABAR detector at center-of-mass energies near 10.6 GeV. The ISR luminosity determined a study leptonic mu+ mu- gamma (gamma). leading-order hadronic contribution muon magnetic anomaly calculated pi measured 1.8 (514.1 +-2.2(stat} +-3.1(syst}) x 10^{-10}.
We present a study of the decays B^{0,+} --> J/psi pi^+ pi^- pi^0 K^{0,+}, using 467 10^6 BBbar pairs recorded with BABAR detector. evidence for decay mode X(3872) omega, product branching fractions B(B^+ X(3872)K^+) B(X(3872) omega) =[0.6\pm0.2\stat \pm 0.1\syst ] 10^{-5}, and B(B^0 X(3872)K^0) =[0.6\pm0.3\stat 10^{-5}. A detailed mass distribution from favors negative-parity assignment.
We present a study of the decays B0,+→J/ψωK0,+ using 383×106 B¯¯¯B events obtained with BABAR detector at PEP-II. observe Y(3940)→J/ψω, mass 3914.6+3.8−3.4(stat)±2.0(syst) MeV/c2, and width 34+12−8(stat)±5(syst) MeV. The ratio B0 B+ decay to YK is 0.27+0.28−0.23(stat)+0.04−0.01(syst), relevant branching fractions are reported.Received 14 November 2007DOI:https://doi.org/10.1103/PhysRevLett.101.082001©2008 American Physical Society
We report the results of a search for $Z(4430)^-$ decay to $J/\psi\pi^-$ or $\psi(2S)\pi^-$ in $B^{-,0}\to \jpsi\pi^- K^{0,+}$ and \psitwos \pi^- decays. The data were collected with BABAR detector at SLAC PEP-II asymmetric-energy $e^+e^-$ collider operating center mass energy 10.58 \gev, sample corresponds an integrated luminosity 413 fb$^{-1}$. Each $K\pi$ distribution exhibits clear $K^{\ast}(892)$ $K^{\ast}_2(1430)$ signals, efficiency-corrected spectrum is well-described by...
We present a study of resonances in exclusive decays $B$ mesons to ${\overline{D}}^{(*)}{D}^{(*)}K$. report the observation $B\ensuremath{\rightarrow}{\overline{D}}^{(*)}{D}_{s1}^{+}(2536)$ where ${D}_{s1}^{+}(2536)$ is reconstructed ${D}^{*0}{K}^{+}$ and ${D}^{*+}{K}_{S}^{0}$ decay channels. also $B\ensuremath{\rightarrow}\ensuremath{\psi}(3770)K$ $\ensuremath{\psi}(3770)$ ${\overline{D}}^{0}{D}^{0}$ ${D}^{\ensuremath{-}}{D}^{+}$. In addition, we an enhancement for...
We present an analysis of exclusive charmless semileptonic B-meson decays based on 377 million BBbar pairs recorded with the BABAR detector at Upsilon(4S) resonance. select four event samples corresponding to decay modes B0 --> pi- l+ nu, B+ pi0 rho- and -> rho0 find measured branching fractions be consistent isospin symmetry. Assuming symmetry, we combine two B pi l nu samples, similarly rho measure BF(B0 nu) = (1.41 +- 0.05 0.07) x 10^-4 (1.75 0.15 0.27) 10^-4, where errors are statistical...
We study the reactions e+e−→e+e−η(') in single-tag mode and measure γγ∗→η(') transition form factors momentum-transfer range from 4 to 40 GeV2. The analysis is based on 469 fb−1 of integrated luminosity collected at PEP-II with BABAR detector e+e− center-of-mass energies near 10.6 GeV.11 MoreReceived 5 January 2011DOI:https://doi.org/10.1103/PhysRevD.84.052001© 2011 American Physical Society
We present a measurement of the total branching fraction flavor-changing neutral-current process B->Xsl+l-, along with partial fractions in bins dilepton and hadronic system (Xs) mass, using sample 471x10^6 Upsilon(4S)->BBbar events recorded BaBar detector at PEP-II e+e- collider. B mesons are reconstructed by combining pair, either or mu+mu-, 10 different Xs final states containing exactly one charged neutral kaon, two fewer pions, most pi0. Using sum over these exclusive modes as basis for...
The authors review the experimental measurements and theoretical descriptions of leptonic semileptonic decays particles containing a single heavy quark, either charm or bottom. Measurements bottom are used to determine magnitudes two fundamental parameters standard model, Cabibbo-Kobayashi-Maskawa matrix elements ${V}_{\mathrm{cb}}$ ${V}_{\mathrm{ub}}$. These connected with physics quark flavor mass, they have important implications for breakdown $\mathrm{CP}$ symmetry. To extract precise...
We present evidence for D0-D(0) mixing in D(0)-->K(+)pi(-) decays from 384 fb(-1) of e(+)e(-) colliding-beam data recorded near square root s=10.6 GeV with the BABAR detector at PEP-II storage rings Stanford Linear Accelerator Center. find parameters x('2)=[-0.22+/-0.30(stat)+/-0.21(syst)] x 10(-3) and y(')=[9.7+/-4.4(stat)+/-3.1(syst)] a correlation between them -0.95. This result is inconsistent no-mixing hypothesis significance 3.9 standard deviations. measure R(D), ratio doubly...
We report a direct measurement of D0−D¯0 mixing parameters through time-dependent amplitude analysis the Dalitz plots D0→KS0π+π− and, for first time, D0→KS0K+K− decays. The low-momentum pion πs+ in decay D*+→D0πs+ identifies flavor neutral D meson at its production. Using 468.5 fb−1 e+e− colliding-beam data recorded near s=10.6 GeV by BABAR detector PEP-II asymmetric-energy collider SLAC, we measure x=[1.6±2.3(stat)±1.2(syst)±0.8(model)]×10−3, and y=[5.7±2.0(stat)±1.3(syst)±0.7(model)]×10−3....
We observe the decays ${D}_{s1}^{*}(2710{)}^{+}\ensuremath{\rightarrow}{D}^{*}K$ and ${D}_{sJ}^{*}(2860{)}^{+}\ensuremath{\rightarrow}{D}^{*}K$ measure their branching fractions relative to $DK$ final state. also observe, in ${D}^{*}K$ mass spectrum, a new broad structure at of $(3044\ifmmode\pm\else\textpm\fi{}{8}_{\mathrm{stat}}(\genfrac{}{}{0}{}{+30}{\ensuremath{-}5}{)}_{\mathrm{syst}})\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ having width...
We present a measurement of the branching fraction and photon energy spectrum for decay B --> X_s gamma using data from BaBar experiment. The sample corresponds to an integrated luminosity 210 fb^{-1}, which approximately 680 000 BB events are tagged by fully reconstructed hadronic one mesons. In second meson, isolated high--energy is identified. measure BR(B gamma) = (3.66 +- 0.85_{stat} 0.60_{syst}) x 10^{-4} energies E_gamma above 1.9 GeV in rest frame. From measured we calculate first...
We perform a study of the exclusive production $D\overline{D}$, ${D}^{*}$$\overline{D}$, and ${D}^{*}{\overline{D}}^{*}$ in initial-state-radiation events, from ${e}^{+}{e}^{\ensuremath{-}}$ annihilations at center-of-mass energy near 10.58 GeV, to search for charmonium possible new resonances. The data sample corresponds an integrated luminosity $384\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ was recorded by BABAR experiment PEP-II storage rings. ${D}^{*}\overline{D}$, mass spectra...
We present measurements of the semileptonic decays B--->D0tau-nutau, B--->D*0tau-nutau, B0-->D+tau-nutau, and B0-->D*+tau-nutau, which are potentially sensitive to non-standard model amplitudes. The data sample comprises 232x10(6) Upsilon(4S)-->BB collected with BABAR detector. From a combined fit B- B0 channels, we obtain branching fractions B(B-->Dtau-nutau)=(0.86+/-0.24+/-0.11+/-0.06)% B(B-->D*tau-nutau)=(1.62+/-0.31+/-0.10+/-0.05)% (normalized for B0), where uncertainties statistical,...
We present a study of excited charm-strange baryon states produced in $e^+e^-$ annihilations at or near center-of-mass energy $10.58\mathrm{Ge\kern -0.1em V}$, data sample with an integrated luminosity $384 fb^{-1}$ recorded the BABAR detector PEP-II storage rings Stanford Linear Accelerator Center. strong decays baryons to $\Lambda_c^+K^0_{\scriptscriptstyle S}$, $\Lambda_c^+K^-$, $\Lambda_c^+K^-\pi^+$, S}\pi^-$, S}\pi^-\pi^+$, and $\Lambda_c^+K^-\pi^+\pi^-$. This confirms existence...
A search for the Z(3930) resonance in gamma production of DDbar system has been performed using a data sample corresponding to an integrated luminosity 384 fb^-1 recorded by BABAR experiment at PEP-II asymmetric-energy electron-positron collider. The invariant mass distribution shows clear evidence state with significance 5.8 sigma. We determine and width values (3926.7 +- 2.7 1.1) MeV/c^2 (21.3 6.8 3.6) MeV, respectively. decay angular analysis provides that is tensor positive parity...
We present a measurement of the Cabibbo-Kobayashi-Maskawa matrix element $|{V}_{\mathrm{cb}}|$ and form-factor slope ${\ensuremath{\rho}}^{2}$ in $\overline{B}\ensuremath{\rightarrow}D{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}}$ decays based on $460\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ events recorded at $\ensuremath{\Upsilon}(4S)$ resonance with BABAR detector. are selected which hadronic decay second $B$ meson is fully...
We study the lepton forward-backward asymmetry ${\mathcal{A}}_{FB}$ and longitudinal ${K}^{*}$ polarization ${F}_{L}$, as well an observable ${P}_{2}$ derived from them, in rare decays $B\ensuremath{\rightarrow}{K}^{*}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$, where ${\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ is either ${e}^{+}{e}^{\ensuremath{-}}$ or ${\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$, using full sample of 471 million...
We have performed a search for the eta_b(1S) meson in radiative decay of Upsilon(2S) resonance using sample 91.6 million events recorded with BABAR detector at PEP-II B factory SLAC National Accelerator Laboratory. observe peak photon energy spectrum E_gamma = 609.3 {+4.6} {-4.5} (stat) +/- 1.9 (syst) MeV, corresponding to an mass 9394.2 {+4.8} {-4.9} 2.0 MeV/c^2. The branching fraction --> gamma is determined be [3.9 +/-1.1 {+1.1} {-0.9} (syst)] x 10^(-4). find ratio fractions B[Upsilon(2S)...
A search for the neutrinoless, lepton-flavor violating decay of $\ensuremath{\tau}$ lepton into three charged leptons has been performed using an integrated luminosity $468\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected with BABAR detector at PEP-II collider. In all six modes considered, numbers events found in data are compatible background expectations. Upper limits on branching fractions set range $(1.8--3.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$ 90% confidence level.