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D. G. Hitlin

Publications and source records attributed to D. G. Hitlin.

At least 37 records · Page 2Linked to original sources
arXiv2016

Design, status and test of the Mu2e crystal calorimeter

The Mu2e experiment at Fermilab searches for the charged-lepton flavor violating neutrino-less conversion of a negative muon into an electron in the field of a aluminum nucleus. The dynamic of such a process is well modeled by a two-body decay, resulting in a monoenergetic electron with an energy slightly below the muon rest mass (104.967 MeV). The calorimeter of this experiment plays an important role to provide excellent particle identification capabilities and an online trigger filter while aiding the track reconstruction capabilities. The baseline calorimeter configuration consists of two disks each made with about 700 undoped CsI crystals read out by two large area UV-extended Silicon Photomultipliers. These crystals match the requirements for stability of response, high resolution and radiation hardness. In this paper we present the final calorimeter design.

physics.ins-det↗
arXiv2016

Measurement of time resolution of the Mu2e LYSO calorimeter prototype

In this paper we present the time resolution measurements of the Lutetium-Yttrium Oxyorthosilicate (LYSO) calorimeter prototype for the Mu2e experiment. The measurements have been performed using the $e^-$ beam of the Beam Test Facility (BTF) in Frascati, Italy in the energy range from 100 to 400 MeV. The calorimeter prototype consisted of twenty five 30x30x130 mm$^3$, LYSO crystals read out by 10x10 mm$^2$ Hamamatsu Avalanche Photodiodes (APDs). The energy dependence of the measured time resolution can be parametrized as $σ_{t}(E)=a/\sqrt{E/\mathrm{GeV}} \oplus b$, with the stochastic and constant terms $a=(51\pm1)$ ps and $b=(10\pm4)$ ps, respectively. This corresponds to the time resolution of ($162\pm4$) ps at 100 MeV.

physics.ins-det↗
arXiv2015

Mu2e Technical Design Report

The Mu2e experiment at Fermilab will search for charged lepton flavor violation via the coherent conversion process mu- N --> e- N with a sensitivity approximately four orders of magnitude better than the current world's best limits for this process. The experiment's sensitivity offers discovery potential over a wide array of new physics models and probes mass scales well beyond the reach of the LHC. We describe herein the preliminary design of the proposed Mu2e experiment. This document was created in partial fulfillment of the requirements necessary to obtain DOE CD-2 approval.

physics.ins-det↗
arXiv2015

Global Fits of the CKM Matrix with the SCAN Method

We present a Scan Method analysis of the allowed region of the rho bar - eta bar plane using the latest input measurements of the CKM matrix elements, sin 2 beta, B0(s,d) mixing, epsilon(K), alpha and gamma. In this approach, we make no assumptions as to the distribution of theory uncertainties; rather, we scan over the range of plausible theoretical uncertainties and determine confidence level contours in the rho bar eta bar plane. We determine alpha from branching fraction and CP asymmetry measurements of B decays to all light pseudoscalar-pseudoscalar, pesudoscalar-vector, vector-vector and a1-psudoscalar mesons and determine gamma from D(*)K(*), D(*) pi and D rho modes, thereby including correlations between the angles of the unitarity triangle. We parametrize the individual decay amplitudes in terms of color-allowed tree, color-suppressed tree, gluonic penguin, singlet penguin, electroweak penguin, as well as W-exchange and W-annihilation amplitudes. Our procedure accounts for all correlations among the fitted CKM parameters (rho bar, eta bar, A, lambda). The data are consistent with the Standard Model with no need for new physics contributions. We also examine example "wall plots", i.e., projections of sensitive parameters showing correlations among them and regions of preferred theoretical parameters.

hep-ex↗
arXiv2014

Evidence for the decay B0 --> omega omega and search for B0 --> omega phi

We describe searches for B meson decays to the charmless vector-vector final states omega omega and omega phi with 471 x 10^6 B Bbar pairs produced in e+ e- annihilation at sqrt(s) = 10.58 GeV using the BABAR detector at the PEP-II collider at the SLAC National Accelerator Laboratory. We measure the branching fraction B(B0 --> omega omega) = (1.2 +- 0.3 +0.3-0.2) x 10^-6, where the first uncertainty is statistical and the second is systematic, corresponding to a significance of 4.4 standard deviations. We also determine the upper limit B(B0 --> omega phi) < 0.7 x 10^-6 at 90% confidence level. These measurements provide the first evidence for the decay B0 --> omega omega, and an improvement of the upper limit for the decay B0 --> omega phi.

hep-ex↗
arXiv2014

Planning the Future of U.S. Particle Physics (Snowmass 2013): Chapter 8: Instrumentation Frontier

These reports present the results of the 2013 Community Summer Study of the APS Division of Particles and Fields ("Snowmass 2013") on the future program of particle physics in the U.S. Chapter 8, on the Instrumentation Frontier, discusses the instrumentation needs of future experiments in the Energy, Intensity, and Cosmic Frontiers, promising new technologies for particle physics research, and issues of gathering resources for long-term research in this area.

hep-ex↗
arXiv2013

Report of the Quark Flavor Physics Working Group

This report represents the response of the Intensity Frontier Quark Flavor Physics Working Group to the Snowmass charge. We summarize the current status of quark flavor physics and identify many exciting future opportunities for studying the properties of strange, charm, and bottom quarks. The ability of these studies to reveal the effects of new physics at high mass scales make them an essential ingredient in a well-balanced experimental particle physics program.

hep-ex↗
arXiv2013

Charged Leptons

This is the report of the Intensity Frontier Charged Lepton Working Group of the 2013 Community Summer Study "Snowmass on the Mississippi", summarizing the current status and future experimental opportunities in muon and tau lepton studies and their sensitivity to new physics. These include searches for charged lepton flavor violation, measurements of magnetic and electric dipole moments, and precision measurements of the decay spectrum and parity-violating asymmetries.

hep-ex↗
arXiv2013

SuperB Technical Design Report

In this Technical Design Report (TDR) we describe the SuperB detector that was to be installed on the SuperB e+e- high luminosity collider. The SuperB asymmetric collider, which was to be constructed on the Tor Vergata campus near the INFN Frascati National Laboratory, was designed to operate both at the Upsilon(4S) center-of-mass energy with a luminosity of 10^{36} cm^{-2}s^{-1} and at the tau/charm production threshold with a luminosity of 10^{35} cm^{-2}s^{-1}. This high luminosity, producing a data sample about a factor 100 larger than present B Factories, would allow investigation of new physics effects in rare decays, CP Violation and Lepton Flavour Violation. This document details the detector design presented in the Conceptual Design Report (CDR) in 2007. The R&D and engineering studies performed to arrive at the full detector design are described, and an updated cost estimate is presented. A combination of a more realistic cost estimates and the unavailability of funds due of the global economic climate led to a formal cancelation of the project on Nov 27, 2012.

physics.ins-det↗
arXiv2013

Study of the decay $\bar{B}^{0}\rightarrowΛ_{c}^{+}\bar{p}π^{+}π^{-}$ and its intermediate states

We study the decay $\bar{B}^{0}\rightarrowΛ_{c}^{+}\bar{p}π^{+}π^{-}$, reconstructing the Λ_{c}^{+} baryon in the $p K^{-}π^{+}$ mode, using a data sample of $467\times 10^{6}$ $B\bar{B}$ pairs collected with the BaBar detector at the PEP-2 storage rings at SLAC. We measure branching fractions for decays with intermediate $Σ_{c}$ baryons to be ${\cal B}[\bar{B}^{0}\rightarrowΣ_{c}(2455)^{++}\bar{p}π^{-}]=(21.3 \pm 1.0 \pm 1.0 \pm 5.5) \times 10^{-5}$, ${\cal B}[\bar{B}^{0}\rightarrowΣ_{c}(2520)^{++}\bar{p}π^{-}]=(11.5\pm 1.0 \pm 0.5 \pm 3.0)\times 10^{-5}$, ${\cal B}[\bar{B}^{0}\rightarrowΣ_{c}(2455)^{0}\bar{p}π^{+}]=(9.1 \pm 0.7 \pm 0.4 \pm 2.4)\times10^{-5}$, and ${\cal B}[\bar{B}^{0}\rightarrowΣ_{c}(2520)^{0}\bar{p}π^{+}]= (2.2 \pm 0.7 \pm 0.1\pm 0.6) \times 10^{-5}$, where the uncertainties are statistical, systematic, and due to the uncertainty on the $Λ_{c}^{+}\rightarrow\proton\Kmπ^{+}$ branching fraction, respectively. For decays without $Σ_{c}(2455)$ or $Σ_{c}(2520)$ resonances, we measure ${\cal B}[\bar{B}^{0}\rightarrowΛ_{c}^{+}\bar{p}π^{+}π^{-}]_{\mathrm{non-Σ_{c}}}=(79 \pm 4 \pm 4 \pm 20)\times10^{-5}$. The total branching fraction is determined to be ${\cal B}[\bar{B}^{0}\rightarrowΛ_{c}^{+}\bar{p}π^{+}π^{-}]_{\mathrm{total}}=(123 \pm 5 \pm 7 \pm 32)\times10^{-5}$. We examine multibody mass combinations in the resonant three-particle $Σ_{c}\bar{p}π$ final states and in the four-particle $Λ_{c}^{+}\bar{p}π^{+}π^{-}$ final state, and observe different characteristics for the $\bar{p}π$ combination in neutral versus doubly-charged $Σ_{c}$ decays.

hep-ex↗
arXiv2013

Search for direct CP-violation in singly-Cabibbo suppressed D+- --> K+ K- pi+- decays

We report on a search for direct CP asymmetry in the singly Cabibbo-suppressed decay D+- --> K+ K- pi+- using a data sample of 476 fb-1 accumulated with the BaBar detector running at and just below the Y(4S) resonance. The CP-violating decay rate asymmetry A_CP is determined to be (0.35 +- 0.30 +- 0.15)%. Model-dependent and model-independent Dalitz plot analysis techniques are used to search for CP-violating asymmetries in the various intermediate states.

hep-ex↗
arXiv2013

Observation of Time Reversal Violation in the B0 Meson System

Although CP violation in the B meson system has been well established by the B factories, there has been no direct observation of time reversal violation. The decays of entangled neutral B mesons into definite flavor states ($B^0$ or $\bar{B}^0$), and $J/ψK_S^0$ or $c\bar{c} K_S^0$ final states (referred to as $B_+$ or $B_-$), allow comparisons between the probabilities of four pairs of T-conjugated transitions, for example, $\bar{B}^0 \rightarrow B_-$ and $B_- \rightarrow \bar{B}^0$, as a function of the time difference between the two B decays. Using 468 million $B\bar{B}$ pairs produced in $Υ(4S)$ decays collected by the BABAR detector at SLAC, we measure T-violating parameters in the time evolution of neutral B mesons, yielding $ΔS_T^+ = -1.37 \pm 0.14 (stat.) \pm 0.06 (syst.)$ and $ΔS_T^- = 1.17 \pm 0.18 (stat.) \pm 0.11 (syst.)$. These nonzero results represent the first direct observation of T violation through the exchange of initial and final states in transitions that can only be connected by a T-symmetry transformation.

hep-ex↗
arXiv2012

Mu2e Conceptual Design Report

Mu2e at Fermilab will search for charged lepton flavor violation via the coherent conversion process mu- N --> e- N with a sensitivity approximately four orders of magnitude better than the current world's best limits for this process. The experiment's sensitivity offers discovery potential over a wide array of new physics models and probes mass scales well beyond the reach of the LHC. We describe herein the conceptual design of the proposed Mu2e experiment. This document was created in partial fulfillment of the requirements necessary to obtain DOE CD-1 approval, which was granted July 11, 2012.

physics.ins-det↗
arXiv2012

Branching fraction and form-factor shape measurements of exclusive charmless semileptonic B decays, and determination of |V_{ub}|

We report the results of a study of the exclusive charmless semileptonic decays, B^0 --> pi^- l^+ nu, B^+ --> pi^0 l^+ nu, B^+ --> omega l^+ nu, B^+ --> eta l^+ nu and B^+ --> eta^' l^+ nu, (l = e or mu) undertaken with approximately 462x10^6 B\bar{B} pairs collected at the Upsilon(4S) resonance with the BABAR detector. The analysis uses events in which the signal B decays are reconstructed with a loose neutrino reconstruction technique. We obtain partial branching fractions in several bins of q^2, the square of the momentum transferred to the lepton-neutrino pair, for B^0 --> pi^- l^+ nu, B^+ --> pi^0 l^+ nu, B^+ --> omega l^+ nu and B^+ --> eta l^+ nu. From these distributions, we extract the form-factor shapes f_+(q^2) and the total branching fractions BF(B^0 --> pi^- l^+ nu) = (1.45 +/- 0.04_{stat} +/- 0.06_{syst})x10^-4 (combined pi^- and pi^0 decay channels assuming isospin symmetry), BF(B^+ --> omega l^+ nu) = (1.19 +/- 0.16_{stat} +/- 0.09_{syst})x10^-4 and BF(B^+ --> eta l^+ nu) = (0.38 +/- 0.05_{stat} +/- 0.05_{syst})x10^-4. We also measure BF(B^+ --> eta^' l^+ nu) = (0.24 +/- 0.08_{stat} +/- 0.03_{syst})x10^-4. We obtain values for the magnitude of the CKM matrix element V_{ub} by direct comparison with three different QCD calculations in restricted q^2 ranges of B --> pi l^+ nu decays. From a simultaneous fit to the experimental data over the full q^2 range and the FNAL/MILC lattice QCD predictions, we obtain |V_{ub}| = (3.25 +/- 0.31)x10^-3, where the error is the combined experimental and theoretical uncertainty.

hep-ex↗
arXiv2012

Initial-State Radiation Measurement of the e+e- -> pi+pi-pi+pi- Cross Section

We study the process e+e- -> pi+pi-pi+pi-gamma, with a photon emitted from the initial-state electron or positron, using 454.3 fb^-1 of data collected with the BABAR detector at SLAC, corresponding to approximately 260,000 signal events. We use these data to extract the non-radiative sigma(e+e- ->pi+pi-pi+pi-) cross section in the energy range from 0.6 to 4.5 Gev. The total uncertainty of the cross section measurement in the peak region is less than 3%, higher in precision than the corresponding results obtained from energy scan data.

hep-ex↗
arXiv2012

A Measurement of the Semileptonic Branching Fraction of the B_s Meson

We report a measurement of the inclusive semileptonic branching fraction of the B_s meson using data collected with the BaBar detector in the center-of-mass (CM) energy region above the Upsilon(4S) resonance. We use the inclusive yield of phi mesons and the phi yield in association with a high-momentum lepton to perform a simultaneous measurement of the semileptonic branching fraction and the production rate of B_s mesons relative to all B mesons as a function of CM energy. The inclusive semileptonic branching fraction of the B_s meson is determined to be B(B_s to l nu X)=9.5 (+2.5/-2.0)(stat)(+1.1/-1.9)(syst)%, where l indicates the average of e and mu.

hep-ex↗
arXiv2011

Study of radiative bottomonium transitions using converted photons

We use 111+/-1 million Upsilon(3S) and 89+/-1 million Upsilon(2S) events recorded by the BaBar detector at the PEP-II B-factory at SLAC to perform a study of radiative transitions between bottomonium states using photons that have been converted to e+e- pairs by the detector material. We observe Upsilon(3S) -> gamma chi_b0,2(1P) decay, make precise measurements of the branching fractions for chi_b1,2(1P,2P) -> gamma Upsilon(1S) and chi_b1,2(2P) -> gamma Upsilon(2S) decays, and search for radiative decay to the eta_b(1S) and eta_b(2S) states.

hep-ex↗