Simultaneous Measurement of the B0 Meson Lifetime and Mixing Frequency with B0 --] D*- 1+ Nu Decays PDF Download
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![Simultaneous Measurement of the B0 Meson Lifetime and Mixing Frequency with B0 --] D*- 1+ Nu Decays PDF](https://books.google.com/books/content/images/frontcover/j5hPAQAACAAJ?fife=w150-h200)
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Languages : en
Pages : 23
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We measure the B° lifetime [tau]{sub b°} and the B°-{bar B}° oscillation frequency [Delta]m{sub d} with a sample of approximately 14,000 exclusively reconstructed B{sup 0} 2!D*− l [nu]{sub {ell}} signal events, selected from 23 million B{bar B} pairs recorded at the [Upsilon](4S) resonance with the BABAR detector at the Stanford Linear Accelerator Center. The decay position of the other B is determined with the remaining tracks in the event, and its b-quark flavor at the time of decay is determined with a tagging algorithm that exploits the correlation between the flavor of the b-quark and the charges of its decay products. The lifetime and oscillation frequency are measured simultaneously with an unbinned maximum-likelihood ([Delta]t) that uses, for each event, the measured difference in decay times of the two B mesons ([Delta]t), the calculated uncertainty on [Delta]t, the signal and background probabilities, and b-quark tagging information for the other B. The results are [tau]{sub B{sup 0}} = (1.523{sub -0.023}{sup +0.024} ± 0.022) ps and [Delta]m{sub d} = (0.492 ± 0.018 ± 0.013) ps−1.
![Simultaneous Measurement of the B0 Meson Lifetime and Mixing Frequency with B0 --] D*- 1+ Nu Decays PDF](https://books.google.com/books/content/images/frontcover/j5hPAQAACAAJ?fife=w80-h100)
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Languages : en
Pages : 23
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Book Description
We measure the B° lifetime [tau]{sub b°} and the B°-{bar B}° oscillation frequency [Delta]m{sub d} with a sample of approximately 14,000 exclusively reconstructed B{sup 0} 2!D*− l [nu]{sub {ell}} signal events, selected from 23 million B{bar B} pairs recorded at the [Upsilon](4S) resonance with the BABAR detector at the Stanford Linear Accelerator Center. The decay position of the other B is determined with the remaining tracks in the event, and its b-quark flavor at the time of decay is determined with a tagging algorithm that exploits the correlation between the flavor of the b-quark and the charges of its decay products. The lifetime and oscillation frequency are measured simultaneously with an unbinned maximum-likelihood ([Delta]t) that uses, for each event, the measured difference in decay times of the two B mesons ([Delta]t), the calculated uncertainty on [Delta]t, the signal and background probabilities, and b-quark tagging information for the other B. The results are [tau]{sub B{sup 0}} = (1.523{sub -0.023}{sup +0.024} ± 0.022) ps and [Delta]m{sub d} = (0.492 ± 0.018 ± 0.013) ps−1.
![Simultaneous Measurement of the B0 Meson Lifetime and Mixing Frequency with B0 --] D*- 1+ Nu Decays PDF](https://books.google.com/books/content/images/frontcover/Pw-0DAEACAAJ?fife=w80-h100)
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Languages : en
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We measure the B[sup 0] lifetime[tau][sub b[sup 0]] and the B[sup 0]-[bar B][sup 0] oscillation frequency[Delta]m[sub d] with a sample of approximately 14,000 exclusively reconstructed B[sup 0][yields] D*[sup -][ell][sup+][nu][sub[ell]] signal events, selected from 23 million B[bar B] pairs recorded at the[Upsilon](4S) resonance with the BABAR detector at the Stanford Linear Accelerator Center. The decay position of the other B is determined with the remaining tracks in the event, and its b-quark flavor at the time of decay is determined with a tagging algorithm that exploits the correlation between the flavor of the b-quark and the charges of its decay products. The lifetime and oscillation frequency are measured simultaneously with an unbinned maximum-likelihood ([Delta]t) that uses, for each event, the measured difference in decay times of the two B mesons ([Delta]t), the calculated uncertainty on[Delta]t, the signal and background probabilities, and b-quark tagging information for the other B. The results are[tau][sub B[sup 0]]= (1.523[sub -0.023][sup+0.024][+-] 0.022) ps and[Delta]m[sub d]= (0.492[+-] 0.018[+-] 0.013) ps[sup -1].
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Languages : en
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The neutral B meson, consisting of a b quark and an anti-d quark, can mix (oscillate) to its own anti-particle through second-order weak interactions. The measurement of the mixing frequency can constrain the quark mixing matrix in the Standard Model of particle physics. The PEP-II B-factory at the Stanford Linear Accelerator Center provides a very large data sample that enables us to make measurements with much higher precisions than previous measurements, and to probe physics beyond the Standard Model. The lifetime of the neutral B meson[tau][sub B0] and the B[sup 0]-[bar B][sup 0] mixing frequency[Delta]m[sub d] are measured with a sample of approximately 14,000 exclusively reconstructed B[sup 0][yields] D*[sup -][ell][sup+][nu][sub[ell]] signal events, selected from 23 million B[bar B] pairs recorded at the[Upsilon](4S)resonance with the BABAR detector at the asymmetric-energy e[sup+]e[sup -] collider, PEP-II. The decay position of the exclusively reconstructed B is determined by the charged tracks in the final state, and its b-quark flavor at the time of decay is known unambiguously from the charge of the lepton. The decay position of the other B is determined inclusively, and its b-quark flavor at the time of decay is determined (tagged) with the charge of tracks in the final state, where identified leptons or kaons give the most information. The decay time difference of two B mesons in the event is calculated from the distance between their decay vertices and the Lorentz boost of the center of mass. Additional samples of approximately 50,000 events are selected for studies of background events. The lifetime and mixing frequency, along with wrong-tag probabilities and the time-difference resolution function, are measured simultaneously with an unbinned maximum-likelihood fit that uses, for each event, the measured difference in B decay times ([Delta]t), the calculated uncertainty on[Delta]t, the signal and background probabilities, and b-quark tagging for the other B meson. The results are[tau][sub B[sup 0]]= (1.523[sub -0.023][sup+0.024][+-] 0.022) ps and[Delta]m[sub d]= (0.492[+-] 0.018[+-] 0.013) ps[sup -1], where the first error is statistical and the second is systematic. The statistical correlation coefficient between[tau][sub B[sup 0]] and[Delta]m[sub d] is -0.22. This result is consistent with the current world average values, the total errors are comparable with other most-precise measurements.
![Measurement of the {bar B}° Lifetime and of the B°-{bar B}° Oscillation Frequency Using Partially Reconstructed {bar B}° --] D* L− {anti {nu}}{sub L} Decays PDF](https://books.google.com/books/content/images/frontcover/MPhbAQAACAAJ?fife=w80-h100)
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Languages : en
Pages : 5
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The authors present a simultaneous measurement of the {bar B}° lifetime [tau](B°) and mixing parameter [Delta]m{sub d}. They use a sample of about 50000 {bar B}° --> D* 1 {anti {nu}}(l) partially reconstructed decays identified with the BABAR detector at the PEP-II storage ring at SLAC, where the flavor of the other B meson is determined from the charge of another high momentum lepton in the same event. The preliminary results are: tau(B°) = (1.50 ± 0.008(stat.) ± 0.030(syst.)) ps, [Delta]m{sub d} = (0.523 ± 0.004(stat.) ± 0.007(syst.)) p{sup s}( -1).
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Languages : en
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The Standard Model of particle physics describes the fundamental building blocks of the Universe and their basic interactions. The model naturally describes the time evolution of the basic particles, of which lifetime and mixing are two examples. The neutral B meson, consisting of a bottom quark and an oppositely charged down quark, enjoys a lifetime of about 1.5 ps and the special property of mixing with its antiparticle partner, the [bar B][sup 0]. That is, due to second order weak interactions, the B[sup 0] meson can change into a [bar B][sup 0] meson and back again as it evolves through time. The details of this behavior offer an opportunity to closely examine the Standard Model. In this dissertation, I report on a measurement of the lifetime and mixing frequency of the neutral B meson. Using the semileptonic decay channel B[sup 0] [yields] D*[sup -][ell][sup +][bar [nu]][sub [ell]], we select more than 68,000 signal and background candidates from about 23 million B[bar B] pairs collected in 1999-2000 with the BABAR detector located at the Stanford Linear Accelerator Center. The other B in the event is reconstructed inclusively. By constructing a master probability density function that describes the distribution of decay time differences in the sample, we use a maximum likelihood technique to simultaneously extract the B[sup 0] lifetime and mixing parameters with precision comparable to the year 2000 world average. The results are [tau][sub B[sup 0]] = (1.523[sub -0.023][sup +0.024] [+-] 0.022) ps and [Delta]m[sub d] = (0.492 [+-] 0.018 [+-] 0.013) ps[sup -1]. The statistical correlation coefficient between [tau][sub B[sup 0]] and [Delta]m[sub d] is -0.22. I describe in detail several cutting-edge strategies this analysis uses to study these phenomena, laying important groundwork for the future. I also discuss several extensions of this work to include possible measurements of higher order parameters such as [Delta][Lambda][sub d].
Author: T. Meyer
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Languages : en
Pages : 361
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Book Description
The Standard Model of particle physics describes the fundamental building blocks of the Universe and their basic interactions. The model naturally describes the time evolution of the basic particles, of which lifetime and mixing are two examples. The neutral B meson, consisting of a bottom quark and an oppositely charged down quark, enjoys a lifetime of about 1.5 ps and the special property of mixing with its antiparticle partner, the {bar B}{sup 0}. That is, due to second order weak interactions, the B{sup 0} meson can change into a {bar B}{sup 0} meson and back again as it evolves through time. The details of this behavior offer an opportunity to closely examine the Standard Model. In this dissertation, I report on a measurement of the lifetime and mixing frequency of the neutral B meson. Using the semileptonic decay channel B{sup 0} {yields} D*{sup -}{ell}{sup +}{bar {nu}}{sub {ell}}, we select more than 68,000 signal and background candidates from about 23 million B{bar B} pairs collected in 1999-2000 with the BABAR detector located at the Stanford Linear Accelerator Center. The other B in the event is reconstructed inclusively. By constructing a master probability density function that describes the distribution of decay time differences in the sample, we use a maximum likelihood technique to simultaneously extract the B{sup 0} lifetime and mixing parameters with precision comparable to the year 2000 world average. The results are {tau}{sub B{sup 0}} = (1.523{sub -0.023}{sup +0.024} {+-} 0.022) ps and {Delta}m{sub d} = (0.492 {+-} 0.018 {+-} 0.013) ps{sup -1}. The statistical correlation coefficient between {tau}{sub B{sup 0}} and {Delta}m{sub d} is -0.22. I describe in detail several cutting-edge strategies this analysis uses to study these phenomena, laying important groundwork for the future. I also discuss several extensions of this work to include possible measurements of higher order parameters such as {Delta}{Lambda}{sub d}.
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Languages : en
Pages : 13
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![A Measurement of the Neutral B Meson Lifetime Using Partially Reconstructed B0 -] D*-pi+ Decays PDF](https://books.google.com/books/content/images/frontcover/dLvVjwEACAAJ?fife=w80-h100)
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The neutral B meson lifetime has been measured with the data collected by the BABAR detector at the PEP-II storage ring during the year 2000 for a total integrated luminosity of 20.3 fb[sup -1]. The B[sup 0][yields] D*[sup -][pi][sup+] decays have been selected with a partial reconstruction method in which only the fast pion from the B[sup 0] decay and the slow pion from D*[sup -][yields][bar D][sup 0][pi][sup -] are reconstructed. The B[sup 0] lifetime has been measured to be 1.510[+-] 0.040[+-] 0.038 ps with a sample of 6971[+-] 241 reconstructed signal events.
![Measurement of the B0 Meson Lifetime with Partial Reconstruction of B0-]D*-pi+ and B0-]D*-rho+ Decays PDF](https://books.google.com/books/content/images/frontcover/QtPajwEACAAJ?fife=w80-h100)
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The neutral B meson lifetime is measured with the data collected by the BABAR detector at the PEP-II storage ring during the years 1999 and 2000, with a total integrated luminosity of 20.7 fb[sup -1]. The decays B[sup 0][yields] D*[sup -][pi][sup+] and B[sup 0][yields] D*[sup -][rho][sup+] are selected with a partial-reconstruction technique, yielding samples of 6970[+-] 240 and 5520[+-] 250 signal events, respectively. With these events, the B[sup 0] lifetime is measured to be 1.533[+-] 0.034 (stat.)[+-] 0.038 (syst.) ps. This measurement serves as a test and validation of procedures required to measure the CP violation parameter sin (2[beta]+[gamma]) with partial reconstruction of these modes.
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Languages : en
Pages : 75
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Lifetime measurements for B0 and B+ are presented using semileptonic decays of B mesons from 360 pb-1 of data collected by CDF's lepton plus displaced track trigger. The decays B 2!l[nu]DX, where D is either D +, D0, or D* +, are partially reconstructed from a muon or electron, a displaced track, and a fully reconstructed charm meson. The B 0 and B+ lifetimes are obtained from an unbinned maximum-likelihood fit to the proper decay length distributions. The measured lifetimes are [tau]B 0 = 1.527 ± 0.012(stat.) ± 0.023(syst.)ps and [tau]B + = 1.629 ± 0.013(stat.) ± 0.025(syst.)ps.
