Engineering topics

Eigen, G

Publications and source records attributed to Eigen, G.

89 records · Page 5

DOE OSTI2010

Measurement of the absolute branching fractions for D{sub s}{sup -}{yields}l{sup -}{nu}{sub l} and extraction of the decay constant f{sub D{sub s}}

The absolute branching fractions for the decays D{sub s}{sup -}{yields}l{sup -}{nu}{sub l} (l=e, {mu}, or {tau}) are measured using a data sample corresponding to an integrated luminosity of 521 fb{sup -1} collected at center-of-mass energies near 10.58 GeV with the BABAR detector at the PEP-II e{sup +}e{sup -} collider at SLAC. The number of D{sub s}{sup -} mesons is determined by reconstructing the recoiling system DKX{gamma} in events of the type e{sup +}e{sup -}{yields}DKXD{sub s}{sup *-}, where D{sub s}{sup *-}{yields}D{sub s}{sup -}{gamma} and X represents additional pions from fragmentation. The D{sub s}{sup -}{yields}l{sup -}{nu}{sub l} events are detected by full or partial reconstruction of the recoiling system DKX{gamma}l. The branching fraction measurements are combined to determine the D{sub s}{sup -} decay constant f{sub D{sub s}}=(258.6{+-}6.4{+-}7.5) MeV, where the first uncertainty is statistical and the second is systematic.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2010

Search for B{sup +}{yields}D{sup +}K{sup 0} and B{sup +}{yields}D{sup +}K{sup *0} decays

We report a search for the rare decays B{sup +}{yields}D{sup +}K{sup 0} and B{sup +}{yields}D{sup +}K{sup *0} in an event sample of approximately 465x10{sup 6} BB pairs collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at SLAC National Accelerator Laboratory. We find no significant evidence for either mode and we set 90% probability upper limits on the branching fractions of B(B{sup +}{yields}D{sup +}K{sup 0})<2.9x10{sup -6} and B(B{sup +}{yields}D{sup +}K{sup *0})<3.0x10{sup -6}.

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DOE OSTI2010

Exclusive Production of Ds Ds-, Ds* Ds-, and Ds* Ds*- via e e- Annihilation with Initial-State-Radiation

The authors perform a study of exclusive production of D{sub s}{sup +}D{sub s}{sup -}, D*{sub s}{sup +}D{sub s}{sup -}, and D*{sub s}{sup +}D*{sub s}{sup -} final states in initial-state-radiation events from e{sup +}e{sup -} annihilations at a center-of-mass energy near 10.58 GeV, to search for charmonium 1{sup --} states. The data sample corresponds to an integrated luminosity of 525 fb{sup -1} and was recorded by the BABAR experiment at the PEP-II storage ring. The D{sub s}{sup +} D{sub s}{sup -}, D*{sub s}{sup +}D{sub s}{sup -}, and D*{sub s}{sup +}D*{sub s}{sup -} mass spectra show evidence of the known {psi} resonances. Limits are extracted for the branching ratios of the decays X(4260) {yields} D{sub s}{sup (*)+}D{sub s}{sup (*)-}.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2010

Search for f{sub J}(2220) in Radiative J/{psi} Decays

We present a search for f{sub J}(2220) production in radiative J/{psi}{yields}{gamma}f{sub J}(2220) decays using 460 fb{sup -1} of data collected with the BABAR detector at the SLAC PEP-II e{sup +}e{sup -} collider. The f{sub J}(2220) is searched for in the decays to K{sup +}K{sup -} and K{sub S}{sup 0}K{sub S}{sup 0}. No evidence of this resonance is observed, and 90% confidence level upper limits on the product of the branching fractions for J/{psi}{yields}{gamma}f{sub J}(2220) and f{sub J}(2220){yields}K{sup +}K{sup -}(K{sub S}{sup 0}K{sub S}{sup 0}) as a function of spin and helicity are set at the level of 10{sup -5}, below the central values reported by the Mark III experiment.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2010

Measurement of CP observables in B{sup {+-}{yields}D}{sub CP}K{sup {+-}}decays and constraints on the CKM angle {gamma}

Using the entire sample of 467x10{sup 6} {Upsilon}(4S){yields}BB decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at the SLAC National Accelerator Laboratory, we perform an analysis of B{sup {+-}}{yields}DK{sup {+-}}decays, using decay modes in which the neutral D meson decays to either CP-eigenstates or non-CP-eigenstates. We measure the partial decay rate charge asymmetries for CP-even and CP-odd D final states to be A{sub CP+}=0.25{+-}0.06{+-}0.02 and A{sub CP-}=-0.09{+-}0.07{+-}0.02, respectively, where the first error is the statistical and the second is the systematic uncertainty. The parameter A{sub CP+} is different from zero with a significance of 3.6 standard deviations, constituting evidence for direct CP violation. We also measure the ratios of the charged-averaged B partial decay rates in CP and non-CP decays, R{sub CP+}=1.18{+-}0.09{+-}0.05 and R{sub CP-}=1.07{+-}0.08{+-}0.04. We infer frequentist confidence intervals for the angle {gamma} of the unitarity triangle, for the strong phase difference {delta}{sub B}, and for the amplitude ratio r{sub B}, which are related to the B{sup -}{yields}DK{sup -} decay amplitude by r{sub B}e{sup i({delta}{sub B}-{gamma})}=A(B{sup -}{yields}D{sup 0}K{sup -})/A(B{sup -}{yields}D{sup 0}K{sup -}). Including statistical and systematic uncertainties, we obtain 0.24<r{sub B}<0.45 (0.06<r{sub B}<0.51) and, modulo 180 deg., 11.3 deg. <{gamma}<22.7 deg. or 80.8 deg. <{gamma}<99.2 deg. or 157.3 deg. <{gamma}<168.7 deg. (7.0 deg. <{gamma}<173.0 deg.) at the 68% (95%) confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2010

Search for b{yields}u transitions in B{sup -{yields}}DK{sup -} and D*K{sup -} decays

We report results from an updated study of the suppressed decays B{sup -}{yields}DK{sup -} and B{sup -}{yields}D*K{sup -} followed by D{yields}K{sup +{pi}-}, where D{sup (*)} indicates a D{sup (*)0} or a D{sup (*)0} meson, and D*{yields}D{pi}{sup 0} or D*{yields}D{gamma}. These decays are sensitive to the Cabibbo-Kobayashi-Maskawa unitarity triangle angle {gamma} due to interference between the b{yields}c transition B{sup -}{yields}D{sup (*)0}K{sup -} followed by the doubly Cabibbo-suppressed decay D{sup 0}{yields}K{sup +{pi}-}, and the b{yields}u transition B{sup -}{yields}D{sup (*)0}K{sup -} followed by the Cabibbo-favored decay D{sup 0}{yields}K{sup +{pi}-}. We also report an analysis of the decay B{sup -}{yields}D{sup (*){pi}-} with the D decaying into the doubly Cabibbo-suppressed mode D{yields}K{sup +{pi}-}. Our results are based on 467x 10{sup 6} {Upsilon}(4S){yields}BB decays collected with the BABAR detector at SLAC. We measure the ratios R{sup (*)} of the suppressed ([K{sup +{pi}-}]{sub D}K{sup -}/{pi}{sup -}) to favored ([K{sup -{pi}+}]{sub D}K{sup -}/{pi}{sup -}) branching fractions as well as the CP asymmetries A{sup (*)} of those modes. We see indications of signals for the B{sup -}{yields}DK{sup -} and B{sup -}{yields}D{sub D{pi}}{sup 0}*K{sup -} suppressed modes, with statistical significances of 2.1 and 2.2{sigma}, respectively, and we measure: R{sub DK}=(1.1{+-}0.6{+-}0.2)x10{sup -2}, A{sub DK}=-0.86{+-}0.47{sub -0.16}{sup +0.12}, R{sub (D{pi}{sup 0})K}*=(1.8{+-}0.9{+-} 0.4)x10{sup -2}, A{sub (D{pi}{sup 0})K}*=+0.77{+-}0.35{+-}0.12, R{sub (D{gamma})K}*=(1.3{+-}1.4{+-}0.8)x10{sup -2},A{sub (D{gamma})K}*=+0.36 {+-}0.94{sub -0.41}{sup +0.25}, where the first uncertainty is statistical and the second is systematic. We use a frequentist approach to obtain the magnitude of the ratio r{sub B{identical_to}}|A(B{sup -}{yields}D{sup 0}K{sup -})/A(B{sup -}{yields}D{sup 0}K{sup -})|=(9.5{sub -4.1}{sup +5.1})%, with r{sub B}<16.7% at 90% confidence level. In the case of B{sup -}{yields}D*K{sup -} we find r{sub B}*{identical_to}|A(B{sup -}{yields}D*{sup 0}K{sup -})/A(B{sup -}{yields}D*{sup 0}K{sup -})|=(9.6{sub -5.1}{sup +3.5})%, with r{sub B}*<15.0% at 90% confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2010

Evidence for Direct CP Violation in the Measurement of the Cabbibo-Kobayashi-Maskawa Angle {gamma} with B{sup {+-}}{yields}D()K{sup (){+-}} Decays

We report the measurement of the Cabibbo-Kobayashi-Maskawa CP-violating angle {gamma} through a Dalitz plot analysis of neutral D-meson decays to K{sub S}{sup 0}{pi}{sup +}{pi}{sup -} and K{sub S}{sup 0}K{sup +}K{sup -} produced in the processes B{sup {+-}}{yields}DK{sup {+-}}, B{sup {+-}}{yields}D*K{sup {+-}} with D*{yields}D{pi}{sup 0}, D{gamma}, and B{sup {+-}}{yields}DK*{sup {+-}} with K*{sup {+-}}{yields}K{sub S}{sup 0}{pi}{+-}, using 468 million BB pairs collected by the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at SLAC. We measure {gamma}=(68{+-}14{+-}4{+-}3) deg. (modulo 180 deg.), where the first error is statistical, the second is the experimental systematic uncertainty, and the third reflects the uncertainty in the description of the neutral D decay amplitudes. This result is inconsistent with {gamma}=0 (no direct CP violation) with a significance of 3.5 standard deviations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2010

Study of B{yields}X{gamma} decays and determination of |V{sub td}/V{sub ts}|

Using a sample of 471x10{sup 6} BB events collected with the BABAR detector, we study the sum of seven exclusive final states B{yields}X{sub s(d){gamma}}, where X{sub s(d)} is a strange (nonstrange) hadronic system with a mass of up to 2.0 GeV/c{sup 2}. After correcting for unobserved decay modes, we obtain a branching fraction for b{yields}d{gamma} of (9.2{+-}2.0(stat){+-}2.3(syst))x10{sup -6} in this mass range, and a branching fraction for b{yields}s{gamma} of (23.0{+-}0.8(stat){+-}3.0(syst))x10{sup -5} in the same mass range. We find (B(b{yields}d{gamma})/B(b{yields}s{gamma}))=0.040{+-}0.009(stat){+-}0.010(syst), from which we determine |V{sub td}/V{sub ts}|=0.199{+-}0.022(stat){+-}0.024(syst){+-}0.002(th).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2010

Measurement of CP violation observables and parameters for the decays $B^{\pm}\to DK^{*\pm}$

We study the decay B{sup -} {yields} DK*{sup -} using a sample of 379 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} events collected with the BABAR detector at the PEP-II B-factory. We perform a 'GLW' analysis where the D meson decays into either a CP-even (CP+) eigenstate (K{sup +}K{sup -}, {pi}{sup +}{pi}{sup -}), CP-odd (CP-) eigenstate (K{sub S}{sup 0}{pi}{sup 0}, K{sub S}{sup 0}{phi}, K{sub S}{sup 0}{omega}) or a non-CP state (K{sup -}{pi}{sup +}). We also analyze D meson decays into K{sup +}{pi}{sup -} from a Cabibbo-favored {bar D}{sup 0} decay or doubly suppressed D{sup 0} decay ('ADS' analysis). We measure observables that are sensitive to the CKM angle {gamma}: the partial-rate charge asymmetries A{sub CP{+-}}, the ratios R{sub CP{+-}} of the B-decay branching fractions in CP{+-} and non-CP decay, the ratio R{sub ADS} of the charge-averaged branching fractions, and the charge asymmetry A{sub ADS} of the ADS decays: A{sub CP+} = 0.09 {+-} 0.13 {+-} 0.06, A{sub CP-} = -0.23 {+-} 0.21 {+-} 0.07, R{sub CP+} = 2.17 {+-} 0.35 {+-} 0.09, R{sub CP-} = 1.03 {+-} 0.27 {+-} 0.13, R{sub ADS} = 0.066 {+-} 0.031 {+-} 0.010, and A{sub ADS} = -0.34 {+-} 0.43 {+-} 0.16, where the first uncertainty is statistical and the second is systematic. Combining all the measurements and using a frequentist approach yields the magnitude of the ratio between the Cabibbo-suppressed and favored amplitudes, r{sub B} = 0.31 with a one (two) sigma confidence level interval of [0.24, 0.38] ([0.17, 0.43]). The value r{sub B} = 0 is excluded at the 3.3 sigma level. A similar analysis excludes values of {gamma} in the intervals [0, 7]{sup o}, [55, 111]{sup o}, and [175, 180]{sup o} ([85, 99]{sup o}) at the one (two) sigma confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2010

Observation of the decay B0bar -> LambdaC antiproton pi0

In a sample of 467 million B{bar B} pairs collected with the BABAR detector at the PEP-II collider at SLAC we have observed the decay {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +}{bar p}{pi}{sup 0} and measured the branching fraction to be (1.94 {+-} 0.17 {+-} 0.14 {+-} 0.50) x 10{sup -4}, where the uncertainties are statistical, systematic, and the uncertainty on the {Lambda}{sub c}{sup +} {yields} pK{sup -}{pi}{sup +} branching fraction, respectively. We determine an upper limit of 1.5 x 10{sup -6} at 90% C.L. for the product branching fraction {Beta}({bar B}{sup 0} {yields} {Sigma}{sub c}{sup +}(2455){bar p}) x {Beta}({Lambda}{sub c}{sup +} {yields} pK{sup -}{pi}{sup +}). Furthermore, we observe an enhancement at the threshold of the invariant mass of the baryon-antibaryon pair.

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DOE OSTI2010

B-meson decays to eta' rho, eta' f0, and eta' K*

We present measurements of B-meson decays to the final states {eta}{prime} {rho}, {eta}{prime} f{sub 0}, and {eta}{prime} K*, where K* stands for a vector, scalar, or tensor strange meson. We observe a significant signal or evidence for {eta}{prime} {rho}{sup +} and all the {eta}{prime}K* channels. We also measure, where applicable, the charge asymmetries, finding results consistent with no direct CP violation in all cases. The measurements are performed on a data sample consisting of 467 x 10{sup 6} B{bar B} pairs, collected with the BABAR detector at the PEP-II e{sup +}e{sup -} collider at the SLAC National Accelerator Laboratory. Our results favor the theoretical predictions from perturbative QCD and QCD Factorization and we observe an enhancement of the tensor K*{sub 2} (1430) with respect to the vector K*(892) component.

43 PARTICLE ACCELERATORS↗

DOE OSTI2010

Search for Production of Invisible Final States in Single-Photon Decays of Upsilon(1S)

We search for single-photon decays of the {Upsilon}(1S) resonance, {Upsilon} {yields} {gamma} + invisible, where the invisible state is either a particle of definite mass, such as a light Higgs boson A{sup 0}, or a pair of dark matter particles, {chi}{bar {chi}}. Both A{sup 0} and {chi} are assumed to have zero spin. We tag {Upsilon}(1S) decays with a dipion transition {Upsilon}(2S) {yields} {pi}{sup +}{pi}{sup -}{Upsilon}(1S) and look for events with a single energetic photon and significant missing energy. We find no evidence for such processes in the mass range m{sub A{sup o}} {le} 9.2GeV and m{sub {chi}} {le} 4.5GeV in the sample of 98 x 10{sup 6} {Upsilon}(2S) decays collected with the BABAR detector and set stringent limits on new physics models that contain light dark matter states.

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DOE OSTI2010

Measurement of D{sup 0}-D{sup 0} Mixing Parameters Using D{sup 0}{yields}K{sub S}{sup 0}{pi}{sup +}{pi}{sup -} and D{sup 0}{yields}K{sub S}{sup 0}K{sup +}K{sup -} Decays

We report a direct measurement of D{sup 0}-D{sup 0} mixing parameters through a time-dependent amplitude analysis of the Dalitz plots of D{sup 0}{yields}K{sub S}{sup 0}{pi}{sup +}{pi}{sup -} and, for the first time, D{sup 0}{yields}K{sub S}{sup 0}K{sup +}K{sup -} decays. The low-momentum pion {pi}{sub s}{sup +} in the decay D{sup *+{yields}}D{sup 0{pi}}{sub s}{sup +} identifies the flavor of the neutral D meson at its production. Using 468.5 fb{sup -1} of e{sup +}e{sup -} colliding-beam data recorded near {radical}(s)=10.6 GeV by the BABAR detector at the PEP-II asymmetric-energy collider at SLAC, we measure the mixing parameters x=[1.6{+-}2.3(stat){+-}1.2(syst){+-}0.8(model)]x10{sup -3}, and y=[5.7{+-}2.0(stat){+-}1.3(syst){+-}0.7(model)]x10{sup -3}. These results provide the best measurement to date of x and y. The knowledge of the value of x, in particular, is crucial for understanding the origin of mixing.

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DOE OSTI2010

Super B Progress Report for Physics

Super B is a high luminosity e + e - collider that will be able to indirectly probe new physics at energy scales far beyond the reach of any man made accelerator planned or in existence. Just as detailed understanding of the Standard Model of particle physics was developed from stringent constraints imposed by flavour changing processes between quarks, the detailed structure of any new physics is severely constrained by flavour processes. In order to elucidate this structure it is necessary to perform a number of complementary studies of a set of golden channels. With these measurements in hand, the pattern of deviations from the Standard Model behavior can be used as a test of the structure of new physics. If new physics is found at the LHC, then the many golden measurements from Super B will help decode the subtle nature of the new physics. However if no new particles are found at the LHC, Super B will be able to search for new physics at energy scales up to 10-100 TeV. In either scenario, flavour physics measurements that can be made at Super B play a pivotal role in understanding the nature of physics beyond the Standard Model. Examples for using the interplay between measurements to discriminate New Physics models are discussed in this document.s detail the Physics case of the Super B Project.

43 PARTICLE ACCELERATORS↗

DOE OSTI2010

Observation of the rare decay B{sup 0}{yields}K{sub S}{sup 0}K{sup {+-}}{pi}{sup {+-}}

We report an analysis of charmless hadronic decays of neutral B mesons to the final state K{sub S}{sup 0}K{sup {+-}}{pi}{sup {+-}}, using a data sample of (465{+-}5)x10{sup 6} BB events collected with the BABAR detector at the {Upsilon}(4S) resonance. We observe an excess of signal events with a significance of 5.2 standard deviations including systematic uncertainties and measure the branching fraction to be B(B{sup 0}{yields}K{sub S}{sup 0}K{sup {+-}}{pi}{sup {+-}})=(3.2{+-}0.5{+-}0.3)x10{sup -6}, where the uncertainties are statistical and systematic, respectively.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2010

Observation of the decay B{sup 0}{yields}{Lambda}{sub c}{sup +}p{pi}{sup 0}

In a sample of 467x10{sup 6} BB pairs collected with the BABAR detector at the PEP-II collider at SLAC we have observed the decay B{sup 0}{yields}{Lambda}{sub c}{sup +}p{pi}{sup 0} and measured the branching fraction to be (1.94{+-}0.17{+-}0.14{+-}0.50)x10{sup -4}, where the uncertainties are statistical, systematic, and the uncertainty on the {Lambda}{sub c}{sup +}{yields}pK{sup -}{pi}{sup +} branching fraction, respectively. We determine an upper limit of 1.5x10{sup -6} at 90% C.L. for the product branching fraction B(B{sup 0}{yields}{Sigma}{sub c}{sup +}(2455)p)xB({Lambda}{sub c}{sup +}{yields}pK{sup -}{pi}{sup +}). Furthermore, we observe an enhancement at the threshold of the invariant mass of the baryon-antibaryon pair.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2010

Measurements of Charged Current Lepton Universality and |V{sub us}| Using Tau Lepton Decays to e{sup -{nu}}{sub e{nu}{tau}}, {mu}{sup -{nu}}{sub {mu}{nu}{tau}}, {pi}{sup -{nu}}{sub {tau},} and K{sup -{nu}}{sub {tau}}

Using 467 fb{sup -1} of e{sup +}e{sup -} annihilation data collected with the BABAR detector, we measure (B({tau}{sup -{yields}}{mu}-{nu}{sub {mu}{nu}{tau}}))/B({tau}{sup -{yields}}e{sup -{nu}}{sub e{nu}{tau}})=(0.9796{+-}0.0016{+-}0.0036), (B({tau}{sup -{yields}}{pi}-{nu}{sub {tau}})/B({tau}{sup -{yields}}e{sup -{nu}}{sub e{nu}{tau}}))=(0.5945{+-}0.0014{+-}0.0061), and (B({tau}{sup -{yields}}K{sup -{nu}}{sub {tau}})/B({tau}{sup -{yields}}e{sup -{nu}}{sub e{nu}{tau}}))=(0.03882{+-}0.00032{+-}0.00057), where the uncertainties are statistical and systematic, respectively. From these precision {tau} measurements, we test the standard model assumption of {mu}-e and {tau}-{mu} charge current lepton universality and provide determinations of |V{sub us}| experimentally independent of the decay of a kaon.

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