211 Matching Results

Search Results

Advanced search parameters have been applied.

Performance of CDF for B physics

Description: Hadron colliders can be an abundant source of heavy flavor, but pose a challenge to isolate the physics signals from the high backgrounds. The upgraded CDFII detector, with its precise tracking capabilities and powerful trigger system, is well equipped for this task. The detector is described with an emphasis on actual performance and on techniques to maximize the heavy flavor yield. Some first heavy flavor results are summarized.
Date: June 11, 2003
Creator: Oldeman, R.
Partner: UNT Libraries Government Documents Department

Heavy flavor lifetimes and lifetime differences

Description: The authors give an overview of heavy flavour lifetime measurements, focusing on recent results from the Tevatron and the B factories. In the first part of this article we summarize the status and latest measurements of B-hadron lifetimes and lifetime ratios, including some recent result from the Tevatron and the B factories, and compare those results with the predictions from Heavy Quark Expansion (HQE). Future prospects for lifetime measurements at the B factories and the Tevatron are discussed. In the second part, we review the status and prospects of measuring the difference between the lifetimes of the two CP eigenstates in the B{sub s}{sup 0}-{bar B}{sub s}{sup 0} system.
Date: September 17, 2003
Creator: Rademacker, Jonas
Partner: UNT Libraries Government Documents Department

Calculation of 239Pu(n,2n) Cross Section by the Subtraction and the Ratio Methods

Description: The {sup 239}Pu(n,2n) and the {sup 235}U(n,2n) cross section are estimated by applying unitarity in several approaches: a subtraction method and also by using a ratio approach that relates the above cross sections to the {sup 238}U(n,2n) cross section and the {sup 239}Pu(n,2n) cross section to the {sup 235}U(n,2n) cross section, respectively. Also, a self-consistent, simultaneous analysis of the cross section data of four nuclei, {sup 239}Pu, {sup 235}U, {sup 238}U and {sup 232}Th, was undertaken to evaluate the {sup 239}Pu(n,2n) cross section at 11 MeV.
Date: September 28, 2000
Creator: Mavratil, P. & McNabb, D.P.
Partner: UNT Libraries Government Documents Department

Hadronic loops and the OZI rule

Description: Arguments based on unitarity indicate that hadronic loop diagrams should produce large violations of the OZI (Okubo-Zweig-Iizuka) rule. The mechanism by which these corrections are evaded has long been a mystery. We have found that there is an exact cancellation of all such loops in a particular (quark model) limit and that, at least for the rho-->omega system which we have studied in detail, the cancellation is maintained in a realistic calculation which takes into account departures from this limit.
Date: August 1, 1991
Creator: Isgur, Nathan
Partner: UNT Libraries Government Documents Department

NLO conformal symmetry in the Regge limit of QCD

Description: The authors show that a scale invariant approximation to the next-to-leading order BFKL kernel, constructed via transverse momentum diagrams, has a simple conformally invariant representation in impact parameter space. That a conformally invariant representation exists is shown first by relating the kernel directly to Feynman diagrams contributing to two photon diffractive dissociation.
Date: September 18, 1996
Creator: Coriano, C.; White, A. R. & Wuesthoff, M.
Partner: UNT Libraries Government Documents Department

Strangeness in the Nucleon or the quark model beyond the valence approximation

Description: Simple arguments based on unitarity indicate that meson loops diagrams, induced by an underlying qq pair creation process, should badly disturb the phenomenologically successful spectroscopy and dynamics of the valence quark model, including such simple but mysterious regularities as the OZI rule. The author discusses some recent progress in adding pair creation to the valence quark model in a way which provides rationale for the quark model's success.
Date: January 1, 1999
Creator: Isgur, Nathan
Partner: UNT Libraries Government Documents Department

A dedicated LHC collider Beauty experiment for precision measurements of CP-violation. LHC-B letter of intent

Description: The LHC-B Collaboration proposes to build a forward collider detector dedicated to the study of CP violation and other rare phenomena in the decays of Beauty particles. The forward geometry results in an average 80 GeV momentum of reconstructed B-mesons and, with multiple, efficient and redundant triggers, yields large event samples. B-hadron decay products are efficiently identified by Ring-Imaging Cerenkov Counters, rendering a wide range of multi-particle final states accessible and providing precise measurements of all angles, {alpha}, {beta} and {gamma} of the unitarity triangle. The LHC-B microvertex detector capabilities facilitate multi-vertex event reconstruction and proper-time measurements with an expected few-percent uncertainty, permitting measurements of B{sub s}-mixing well beyond the largest conceivable values of x{sub S}. LHC-B would be fully operational at the startup of LHC and requires only a modest luminosity to reveal its full performance potential.
Date: March 28, 1996
Creator: Crosetto, Dario B.
Partner: UNT Libraries Government Documents Department

Prospects for measuring K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}} and K{sub L}{sup 0} {r_arrow} {pi}{sup 0} {nu}{bar {nu}} at BNL

Description: Rare kaon decay experiments underway or planned for the BNL AGS will yield new and independent determinations of V*{sub ts}V{sub td}. A measurement of B(K{sub L}{sup 0} {r_arrow} {pi}{sup 0} {nu}{bar {nu}}) allows a determination of the imaginary part of this quantity, which is the fundamental CP-violating parameter of the Standard Model, in a uniquely clean manner. Since the measurement of B(K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}}) determines {vert_bar}V*{sub ts}V{sub td}, a complete derivation of the unitarity triangle is facilitated. These results can be compared to high precision data expected to come from the B sector in a number of ways, allowing for unique tests of new physics.
Date: September 18, 2000
Creator: Bryman, D.A. & Littenberg, L.
Partner: UNT Libraries Government Documents Department

Weak interaction studies with an on-line Penning trap mass spectrometer.

Description: Superallowed {beta}-decays are a sensitive probe of the fundamental aspects of the weak interaction. Such decays are used to stringently test the CVC hypothesis, deduce a precise value of the weak vector coupling constant, test the unitarity of the CKM matrix and look for deviation from the V-A structure for the weak interaction. The ability to efficiently capture and store short-lived superallowed beta-emitters in ion traps will help to elucidate discrepancies in the most precise unitarity test of the CKM matrix and tighten the present limits on interactions outside the standard V-A form.
Date: March 10, 1999
Creator: Barber, R. C.; Buchinger, F.; Crawford, J. E.; Feng, X.; Gulick, S.; Hackman, G. et al.
Partner: UNT Libraries Government Documents Department

Higher-order corrections to BFKL evolution from t-channel unitarity

Description: Using reggeon diagrams as a partial implementation of t-channel unitarity, O(g{sup 4}) corrections to the BFKL evolution equation have been obtained. We describe the spectrum and holomorphic factorization properties of the resulting scale-invariant kernel. For a gauge theory, t-channel unitarity can be studied directly in the complex j-plane by implementing Ward identity constraints together with the group structure of reggeon interactions. We discuss how both the O(g{sup 2}) BFKL kernel and the O(g{sup 4}) corrections can then be derived.
Date: 1994-12~
Creator: Coriano, C. & White, A. R.
Partner: UNT Libraries Government Documents Department


Description: Recent highlights in CP violation phenomena, are reviewed. B-factory results imply that, CP-violation phase in the CKM matrix is the dominant contributor to the observed CP violation in K and B-physics. Deviations from the predictions of the CKM-paradigm due to beyond the Standard Model CP-odd phase are likely to be a small perturbation. Therefore, large data sample of clean B's will be needed. Precise determination of the unitarity triangle, along with time dependent CP in penguin dominated hadronic and radiative modes are discussed. Null tests in B, K and top-physics and separate determination of the K-unitarity triangle are also emphasized.
Date: February 27, 2005
Creator: A., SONI
Partner: UNT Libraries Government Documents Department

The No-Higgs Signal: Strong WW Scattering at the LHC

Description: Strong WW scattering at the LHC is discussed as a manifestation of electroweak symmetry breaking in the absence of a light Higgs bosom. The general framework of the Higgs mechanism--with or without a Higgs boson--is reviewed, and unitarity is shown to fix the scale of strong WW scattering. Strong WW scattering is also shown to be a possible outcome of five-dimensional models, which do not employ the usual Higgs mechanism at the TeV scale. Precision electroweak constraints are briefly discussed. Illustrative LHC signals are reviewed for models with QCD-like dynamics, stressing the complementarity of the W{sup {+-}}Z and like-charge W{sup +}W{sup +} + W{sup -}W{sup -} channels.
Date: December 7, 2004
Creator: Chanowitz, Michael S.
Partner: UNT Libraries Government Documents Department

B-factory signals for a warped extra dimension

Description: We study predictions for B-physics in a class of models, recently introduced, with a non-supersymmetric warped extra dimension. In these models few ({approx} 3) TeV Kaluza-Klein masses are consistent with electroweak data due to bulk custodial symmetry. Furthermore, there is an analog of GIM mechanism which is violated by the heavy top quark (just as in SM) leading to striking signals at B-factories: (1) New Physics (NP) contributions to {Delta}F = 2 transitions are comparable to SM. This implies that, within this NP framework, the success of the SM unitarity triangle fit is a ''coincidence''. Thus, clean extractions of unitarity angles via e.g. B {yields} {pi}{pi}, {rho}{pi}, {rho}{rho}, DK are likely to be affected, in addition to O(1) deviation from SM prediction in Bs mixing. (2) O(1) deviation from SM predictions for B {yields} X{sub s}{ell}{sup +}{ell}{sup -} in rate as well as in forward-backward and direct CP asymmetry. (3) Large mixing-induced CP asymmetry in radiative B decays, wherein the SM unambiguously predicts very small asymmetries. Also, with KK masses 3 TeV or less, and with anarchic Yukawa masses, contributions to electric dipole moments of the neutron are roughly 20 times larger than the current experimental bound so that this framework has a ''CP problem''.
Date: August 24, 2004
Creator: Agashe, Kaustubh; Perez, Gilad & Soni, Amarjit
Partner: UNT Libraries Government Documents Department

Performance and first physics results of the SVT trigger at CDF II

Description: For the first time in a hadron collider, a novel trigger processor, the Silicon Vertex Trigger (SVT), allows to select the long-lived heavy flavor particles by cutting on the track impact parameter with a precision similar to that of the offline reconstruction. Triggering on displaced tracks has enriched the B-physics program by enhancing the B yields of the lepton-based triggers and opened up full hadronic triggering at CDF. After a first commissioning period, the SVT is fully operational, performing very closely to its design capabilities. System performance and first physics results based on SVT selected data samples are presented.
Date: December 3, 2003
Creator: Vila, I.
Partner: UNT Libraries Government Documents Department

Bs physics and prospects at the Tevatron

Description: Both experiments CDF and D0 at the Tevatron collider have now the first samples of B{sub s} where preliminary measurements are performed. The mass and lifetime determination is shown and the yield for the hadronic B{sub s} decays, the first step towards the B{sub s} production fraction and Branching Ratio, is discussed. This also sets the bases for a re-evaluation of mixing capabilities in Run II.
Date: June 16, 2003
Creator: Lucchesi, D.
Partner: UNT Libraries Government Documents Department


Description: Present information on established and possible baryons and mesons, its derivation, and its organization on the basis of unitary symmetry are discussed. Some questions of particular interest in connection with the last point are considered. 35 references. (D.C.W.)
Date: January 1, 1963
Creator: Dalitz, R H
Partner: UNT Libraries Government Documents Department

Measurements of the CKM Angle beta

Description: In this article I report on new and updated measurements of the CP-violating parameter {beta}({phi}{sub 1}), which is related to the phase of the Cabibbo-Kobayashi-Maskawa (CKM) quark-mixing matrix of the electroweak interaction. Over the past few years, {beta} has become the most precisely known parameter of the CKM unitarity triangle that governs the B system. The results presented here were produced by the two B Factories, BABAR and Belle, based on their most recent datasets of over 600 million B{bar B} events combined. The new world average for sin2{beta}, measured in the theoretically and experimentally cleanest charmonium modes, such as B{sup 0} {yields} J/{Psi}K{sub S}{sup 0}, is sin 2{beta} = 0.685 {+-} 0.032. In addition to these tree-level dominated decays, independent measurements of sin2{beta} are obtained from gluonic b {yields} s penguin decays, including B{sup 0} {yields} {phi}K{sub S}{sup 0}, B{sup 0} {yields} {eta}'K{sub S}{sup 0} and others. There are hints, albeit somewhat weaker than earlier this year, that these measurements tend to come out low compared to the charmonium average, giving rise to the tantalizing possibility that New Physics amplitudes could be contributing to the corresponding loop diagrams. Clearly, more data from both experiments are needed to elucidate these intriguing differences.
Date: December 14, 2005
Creator: Bartoldus, Rainer
Partner: UNT Libraries Government Documents Department

Lattice QCD results for the B --> D(*) l nu form factors: F(1) and G(1)

Description: I review the current status of lattice QCD calculations of the B {yields} D and B {yields} D* form factors and discuss prospects for their improvement. Successful calculations within the quenched approximation demonstrate the power of lattice methods for calculating F(1) and G(1), and the unquenched calculations in progress should soon allow for a 2-3% exclusive determination of |Vcb|.
Date: January 1, 2007
Creator: Van de Water, R.S.
Partner: UNT Libraries Government Documents Department

B to (rho/omega) gamma at BaBar

Description: This document describes the measurements of the branching fractions and isospin violations of the radiative electroweak penguin decays B {yields} ({rho}/{omega}){gamma} at the asymmetric-energy e{sup +}e{sup -} PEP-II collider with the BABAR detector. Together with the previously measured branching fractions of the decays B {yields} K*{gamma} the ratio of CKM-matrix elements |V{sub td}/V{sub ts}| are extracted and the length of the far side of the unitarity triangle is determined.
Date: February 6, 2008
Creator: Koeneke, Karsten
Partner: UNT Libraries Government Documents Department

BaBar Status and Prospects for CP Asymmetry Measurements: Sin(2beta + gamma)

Description: The recent experimental results on CP violation related to the angles of the Cabibbo-Kobayashi-Maskawa (CKM) unitarity triangle 2{beta} + {gamma} are summarized in these proceedings. These results are obtained with approximately 232 million {Upsilon}(4S) {yields} B{bar B} events collected with the BABAR detector at the PEP-II asymmetric-energy B-factory at SLAC. Using the measurements on time-dependent CP asymmetries in B{sup 0} {yields} D{sup (*){-+}} {pi}{sup {-+}} and B{sup 0} {yields} D{sup {-+}}{rho}{sup {+-}} decays and theoretical assumptions, one finds | sin(2{beta} + {gamma}) | > 0.64 (0.40) at 68% (90%) confidence level. The perspectives of sin(2{beta} + {gamma}) measurement with {bar B}{sup 0} {yields} D{sup (*)0} {bar K}{sup (*)0} and B{sup 0} {yields} D{sup (*){-+}}{alpha}{sub 0(2)}{sup {+-}} decay channels are also discussed.
Date: April 6, 2007
Creator: Ganzhur, Sergey
Partner: UNT Libraries Government Documents Department

Measurement of Sin(2beta) in Tree Dominated B0 Decays And Ambiguity Removal

Description: The most recent results from the B-factories on the time-dependent CP asymmetries measured in B{sup 0}-decays mediated by b {yields} c{bar c}s quark-transitions are reviewed. The Standard Model interpretation of the results in terms of the parameter sin 2{beta} leads to a four-fold ambiguity on the unitarity triangle {beta} which can be reduced to a two-fold ambiguity by measuring the sign of the parameter cos 2{beta}. The results on cos2{beta} obtained so far are reviewed.
Date: November 20, 2007
Creator: Lacker, H.
Partner: UNT Libraries Government Documents Department

Measurement of $\phi_s$ at D{\O} Experiment

Description: Recent measurements of the D0 experiment related to the search for new phenomena beyond the Standard Model are reviewed. The new measurement of the like-sign dimuon charge asymmetry reveals a 3.2{sigma} deviation from the SM prediction, while the updated study of the B{sub s} {yields} J/{psi}{phi} decay demonstrates a better agreement with the SM. All experimental results on the CP violation in mixing are currently consistent with each other. The D0 collaboration has much more statistics to analyze, and all these results can be significantly improved in the future.
Date: January 1, 2011
Creator: Borissov, G.
Partner: UNT Libraries Government Documents Department


Description: In a crossing-symmetric Regge theory with several coupled two-particle channels, there are many-particle absorptive effects due to crossed two-particle processes. Also, some of the partial-wave amplitudes have overlapping left-hand and right-hand cuts in the s-plane, To enforce unitarity in such a theory, one needs a coupled-channel N/D method allowing arbitrary absorption parameters and overlapping cuts. These requirements lead to a nonlinear marginally singular N/D equation, which is proposed as part of a scheme to construct a coupled-channel Regge theory with exact crossing symmetry.
Date: November 1, 1979
Creator: Warnock, Robert Lee
Partner: UNT Libraries Government Documents Department