Penguin-Induced Radiative Baryonic B Decays

Weak radiative baryonic B decays B\to\B_1\ov \B_2\gamma mediated by the electromagnetic penguin process $b\to s\gamma$ have appreciable rates larger than their two-body counterparts B\to\B_1\ov \B_2. The branching ratios for $B^-\to\Lambda\bar p\gamma$ and $B^-\to\Xi^0\bar\Sigma^-\gamma$ are sizable, falling into the range of $(1\sim 6)\times 10^{-6}$ with the value preferred to be on the large side, and not far from the bottom baryon radiative decays $\Lambda_b\to\Lambda\gamma$ and $\Xi_b\to\Xi\gamma$ due to the large short-distance enhancement for $b\to s\gamma$ penguin transition and the large strong coupling of the anti-triplet bottom baryons with the B meson and the light baryon. These penguin-induced radiative baryonic B decay modes should be accessible by B factories.Comment: 8 pages, 1 figure. Branching ratios are corrected as previous values are too large by a factor of 2 and a new reference is adde

LAPORAN TUGAS AKHIR PERANCANGAN INFRASTRUKTUR DARI ASPEK STRUKTURAL, TRANSPORT, KEAIRAN DAN MANAJEMEN KONSTRUKSI ( ANALISA PENGARUH HAMBATAN TERHADAP KECEPATAN KENDARAAN JALAN KUSUMANEGARA )

Perkembangan infrastruktur saat ini sangat lah pesat dan penting dalam menopang kehidupan ekonomi dan sosial masyarakat Indonesia. Dalam membangun infrastruktur yang sesuai dengan stanfdar harus ada perencanaan dan perancangan serta perhitungan yang tepat, sehingga mendapatkan hasil bangunan yang baik. Laporan Tugas Akhir ini memuat rangkuman dari 4 praktik yang telah di tempuh sebelumnya. Keempat praktik itu adalah Praktik Perancangan Bangunan Gedung, Praktik Perancangan Jalan, Praktik Perancangan Bangunan Air, Praktik Perancangan Biaya dan Waktu. Dan yang menjadi fokus penulis adalah Praktik Perancangan Jalan. Pada Praktik Perancangan Bangunan Gedung, penulis melakukan perancangan bangunan 3 lantai di kota solok, Sumatra Barat. Dalam melakukan perancangan bangunan gedung, metode yang di pakai adalah dengan menetukan data structural bangunan yang nantinya di pakai untuk perhitungan guna mendapatkan hasil spesifikasi perencanaan dari atap hingga pondasi. Yang mana mengacu pada peraturan-peraturan pembebanan Standar Nasional Indonesia. Pada Praktik Perancangan Jalan, Penulis melakukan survei dan analis data terkait transportasi di beberapa tempat di Yogyakarta. Metode yang di pakai adalah pengamatan secara langsung atau observasi. Pada Praktik Perancangan Banguna Air, penulis melakukan perencanaan struktur bending. Metode yang di gunakan adalah Metode Poligon Thiessen. Uji sebaran Data yang mana meliputi Uji Chi Kuadrat dan Uji Smirnov-Kolmogrov, Distribusi Log Person III dan Metode Weduwen. Pada Praktik Perencanaan Biaya dan Waktu , penulis merencanakan estimasi biaya dan waktu dari proyek pembangunan Rumah Tinggal Sleman. Penulis di minta merencanakan ulang proyek Pembangunan Rumah Tinggal Sleman di Papua. Dari hasil perancangan bangunan gedung di dapatkan spesifikasi perencanaan bangunan dari atap hingga pondasi. Seperti Profil yang pada gording, kuda-kuda, jenis sambungan, penulangan balok kolom hingga pondasi. Hasil dari survey dan analisis praktik perancangan jalan berupa pengamatan ruas jalan, analis kecepatan, volume, dan kepadatan arus serta analis simpang tak bersinyal. Pada praktik perencanaan bangunan air di dapatkan hasil untuk Bendung Tirtorejo adalah tipe bendung tetap (badan bendung dari beton), tipe puncak bendung bulat, tipe kolam olak USBR tipe III, jumlah pintu pembilas 2 buah dengan jumlah pilar 2 buah dan perencanaan bendung aman terhadap geser, guling, angkat, rembesan dan genpa. Dari hasil praktik perencanaan biaya dan waktu, biaya yang di butuhkan untuk membangun proyek Pembangunan Rumah Tinggal Sleman di Papua lebih besar di banding dengan pembangunan di Sleman. Jumlah perbandingan biaya sebesar Rp 2.035.341.000,00 atau terbilang dua milyar tiga puluh lima juta tiga ratus empat puluh satu juta rupiah. Perbedaan harga yang cukup jauh di pengaruhi oleh harga bahan dan upah pekerja yang sangat tinggi

Final-State Phases in B→B \to Baryon-Antibaryon Decays

The recent observation of the decay \ob \to \Lambda_c^+ \bar p suggests that related decays may soon be visible at $e^+ e^-$ colliders. It is shown how these decays can shed light on strong final-state phases and amplitudes involving the spectator quark, both of which are normally expected to be small in B decays.Comment: 14 pages, LaTeX, 2 figures, submitted to Phys. Rev. D, references and discussion of helicity amplitudes adde

Hadronic B Decays to Charmed Baryons

We study exclusive B decays to final states containing a charmed baryon within the pole model framework. Since the strong coupling for $\Lambda_b\bar B N$ is larger than that for $\Sigma_b \bar BN$, the two-body charmful decay $B^-\to\Sigma_c^0\bar p$ has a rate larger than $\bar B^0\to\Lambda_c^+\bar p$ as the former proceeds via the $\Lambda_b$ pole while the latter via the $\Sigma_b$ pole. By the same token, the three-body decay $\bar B^0\to\Sigma_c^{++}\bar p\pi^-$ receives less baryon-pole contribution than $B^-\to\Lambda_c^+\bar p\pi^-$. However, because the important charmed-meson pole diagrams contribute constructively to the former and destructively to the latter, $\Sigma_c^{++}\bar p\pi^-$ has a rate slightly larger than $\Lambda_c^+\bar p\pi^-$. It is found that one quarter of the $B^-\to \Lambda_c^+\bar p\pi^-$ rate comes from the resonant contributions. We discuss the decays $\bar B^0\to\Sigma_c^0\bar p\pi^+$ and $B^-\to\Sigma_c^0\bar p\pi^0$ and stress that they are not color suppressed even though they can only proceed via an internal W emission.Comment: 25 pages, 6 figure

New CP observables in B0(t) -> hyperon + antihyperon from parity violation in the sequential decay

We consider the decay B0(t) -> hyperon + antihyperon, followed by hyperon weak decay. We show that parity violation in the latter allows to reach new CP observables: not only Im(lambda_f) but also Re(lambda_f) can be measured. In the decay B0_d(t) -> Lambda LambdaBar (BR ~ 10-6), Lambda -> p pi- these observables reduce to sin(2alpha) and cos(2alpha) in the small Penguin limit, the latter solving the discrete ambiguity alpha -> pi/2 -alpha. For beta one could consider the Cabibbo suppressed mode B0_d(t) -> Lambda_c Lambda_cBar (BR \~ 10-4), Lambda_c -> Lambda pi+, p K0bar, ... (with BR ~ 10-2). The pure Penguin modes B0_s(t)->Sigma-Sigma-Bar, Xi-Xi-Bar, Omega-Omega-Bar (BR ~ 10-7) can be useful in the search of CP violation beyond the Standard Model. Because of the small total rates, the study of these modes could only be done in future high statistics experiments. Also, in the most interesting case Lambda LambdaBar the time dependence of the asymmetry can be difficult to reconstruct. On the other hand, we show that B_d mesons, being a coherent source of Lambda LambdaBar, is useful to look for CP violation in Lambda decay. We also discuss B0_d(t) -> J/Psi K*0 -> l+ l- K_S pi0 where the secondary decays conserve parity, and angular correlations allow to determine terms of the form cos(delta)cos(2beta), delta being a strong phase. This phase has been measured by CLEO, but we point out that a discrete ambiguity prevents to determine sign(cos(2beta)). However, if one assumes small strong phases, like in factorization and as supported by CLEO data, one could have information on sign(cos(2beta)). Similar remarks can be done for cos(2alpha) in the decay B_d0(t) -> rho rho -> 4pi.Comment: LaTeX, 35 pages, 4 figures in a separate postscript fil

Another Source of Baryons in BB Meson Decays

It is usually assumed that the production of baryons in $B$ meson decays is induced primarily by the quark level process $b\to c\bar ud$, where the charm quark hadronizes into a charmed baryon. With this assumption, the $\Lambda_c$ momentum spectrum would indicate that the transition $B\to\Lambda_c X$ is dominated by multi-body $B$ decays. However, a closer examination of the momentum spectrum reveals that the mass $m_X$ against which the $\Lambda_c$ is recoiling almost always satisfies m_X\agt m_{\Xi_c}. This fact leads us to examine the hypothesis that the production of charmed baryons in $B$ decays is in fact dominated by the underlying transition $b\to c\bar cs$, and is seen primarily in modes with two charmed baryons in the final state. We propose a number of tests of this hypothesis. If this mechanism is indeed important in baryon production, then there are interesting consequences and applications, including potentially important implications for the ``charm deficit'' in $B$ decays.Comment: 9 pages, 3 uuencoded figures included, uses REVTeX, preprint nos. CALT-68-1935, FERMILAB-PUB-94-132-T, JHU-TIPAC-940006, UCSD/PTH 94-0

Charmless Exclusive Baryonic B Decays

We present a systematical study of two-body and three-body charmless baryonic B decays. Branching ratios for two-body modes are in general very small, typically less than $10^{-6}$, except that \B(B^-\to p \bar\Delta^{--})\sim 1\times 10^{-6}. In general, $\bar B\to N\bar\Delta>\bar B\to N\bar N$ due to the large coupling constant for $\Sigma_b\to B\Delta$. For three-body modes we focus on octet baryon final states. The leading three-dominated modes are $\bar B^0\to p\bar n\pi^-(\rho^-), n\bar p\pi^+(\rho^+)$ with a branching ratio of order $3\times 10^{-6}$ for $\bar B^0\to p\bar n\pi^-$ and $8\times 10^{-6}$ for $\bar B^0\to p\bar n\rho^-$. The penguin-dominated decays with strangeness in the meson, e.g., $B^-\to p\bar p K^{-(*)}$ and $\bar B^0\to p\bar n K^{-(*)}, n\bar n \bar K^{0(*)}$, have appreciable rates and the $N\bar N$ mass spectrum peaks at low mass. The penguin-dominated modes containing a strange baryon, e.g., $\bar B^0\to \Sigma^0\bar p\pi^+, \Sigma^-\bar n\pi^+$, have branching ratios of order $(1\sim 4)\times 10^{-6}$. In contrast, the decay rate of $\bar B^0\to\Lambda\bar p\pi^+$ is smaller. We explain why some of charmless three-body final states in which baryon-antibaryon pair production is accompanied by a meson have a larger rate than their two-body counterparts: either the pole diagrams for the former have an anti-triplet bottom baryon intermediate state, which has a large coupling to the $B$ meson and the nucleon, or they are dominated by the factorizable external $W$-emission process.Comment: 46 pages and 3 figures, to appear in Phys. Rev. D. Major changes are: (i) Calculations of two-body baryonic B decays involving a Delta resonance are modified, and (ii) Penguin-dominated modes B-> Sigma+N(bar)+p are discusse

Charmless Two-body Baryonic B Decays

We study charmless two-body baryonic B decays in a diagramatic approach. Relations on decay amplitudes are obtained. In general there are more than one tree and more than one penguin amplitudes. The number of independent amplitudes can be reduced in the large m_B limit. It leads to more predictive results. Some prominent modes for experimental searches are pointed out.Comment: 15 pages, 2 figures. To appear in Phys. Rev.

Search for Charmless Two-body Baryonic Decays of B Mesons

We report the results of a search for the rare baryonic decays $B^0 \to p\bar{p}$, $\Lambda\bar{\Lambda}$, and $B^+ \to p\bar{\Lambda}$. The analysis is based on a data set of $31.7\times 10^6 B\bar{B}$ events collected by the Belle detector at the KEKB $e^+e^-$ collider. No statistically significant signals are found, and we set branching fraction upper limits ${\mathcal B}(B^0 \to p\bar{p}) < 1.2 \times 10^{-6}$, ${\mathcal B}(B^0 \to \Lambda\bar{\Lambda}) < 1.0 \times 10^{-6}$, and ${\mathcal B}(B^+ \to p\bar{\Lambda}) < 2.2 \times 10^{-6}$ at the 90% confidence level.Comment: 6 pages, 4 figures and 1 table. Submitted to Phys. Rev. D Rapid Communication

Study of the decay mechanism for B+ to p pbar K+ and B+ to p pbar pi+

We study the characteristics of the low mass ppbar enhancements near threshold in the three-body decays B+ to p pbar K+ and B+ to p pbar pi+. We observe that the proton polar angle distributions in the ppbar helicity frame in the two decays have the opposite polarity, and measure the forward-backward asymmetries as a function of the ppbar mass for the p pbar K+ mode. We also search for the intermediate two-body decays, B+ to pbar Delta++ and B+ to p Delta0bar, and set upper limits on their branching fractions. These results are obtained from a 414 fb^{-1} data sample that contains 449 times 10^6 BBbar events collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider.Comment: 15 pages, 5 figures (14 figure files), revisions to Phys. Lett.