4,801 research outputs found

    Collinear factorization violation and effective field theory

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    The factorization of amplitudes into hard, soft and collinear parts is known to be violated in situations where incoming particles are collinear to outgoing ones. This result was first derived by studying limits where non-collinear particles become collinear. We show that through an effective field theory framework with Glauber operators, these factorization-violating effects can be reproduced from an amplitude that is factorized before the splitting occurs. We confirm results at one-loop, through single Glauber exchange, and at two-loops, through double Glauber exchange. To approach the calculation, we begin by reviewing the importance of Glauber scaling for factorization. We show that for any situation where initial state and final state particles are not collinear, the Glauber contribution is entirely contained in the soft contribution. The contributions coming from Glauber operators are necessarily non-analytic functions of external momentum, with the non-analyticity arising from the rapidity regulator. The non-analyticity is critical so that Glauber operators can both preserve factorization when it holds and produce factorization-violating effects when they are present.Comment: 55 Pages, 5 figure

    Clinical study on the optic nerve protection of calcium dobesilate in treating glaucoma

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    AIM:To observe the protective effect of calcium dobesilate on optic nerve of glaucoma patients whose intraocular pressure has been under control through operation.<p>METHODS: A total of 78 inpatients(89 eyes)with glaucoma in this hospital from January, 2011 to February, 2012 were enrolled. All patients were randomly divided into treatment group and control group with 6 months in a course. The visual acuity, visual field(mean sensibility, MS), and intraocular pressure were measured at the experiment onset and 6 months later to evaluate the clinical effect.<p>RESULTS: There were no statistically significant differences in the visual acuity, intraocular pressure between the two groups neither at the experiment onset nor after 6 months(<i>P</i>>0.05). The mean sensibility(MS)of the treatment group was obviously improved(14.56±5.03 <i>vs </i>18.9±5.77, <i>P</i><0.05)with statistically significant differences before and after the treatment, while the MS remained unchanged in the control group(14.75±5.17 <i>vs </i>13.48±4.69). There are statistically significant difference between the treatment group and the control group. Compared to the ratio of improvement, stability, and deterioration in the control group(10.3%, 48.7%, 41.0%), the indexes were changed obviously in the treatment group(64.1%, 28.2%, 7.7%,<i>P</i><0.05)with statistically significant difference between the two groups.<p>CONCLUSION:Calcium dobesilate can improve mean retinal sensitivity and protect the optic nerve in glaucoma patients whose intraocular pressure has been controlled

    Signature of Pseudo Nambu-Goldstone Higgs boson in its Decay

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    If the Higgs boson is a pseudo Nambu-Goldstone boson (PNGB), the hZγhZ\gamma contact interaction induced by the O(p4)\mathcal{O}(p^4) invariants of the non-linear sigma model is free from its nonlinearity effects. The process hZγh\rightarrow Z\gamma can be used to eliminate the universal effects of heavy particles, which can fake the nonlinearity effects of the PNGB Higgs boson in the process hVVh\rightarrow V^*V (V=W±V=W^\pm,\ ZZ). We demonstrate that the ratio of the signal strength of hZγh\rightarrow Z\gamma and hVVh\rightarrow V^*V is good to distinguish the signature of the PNGB Higgs boson from Higgs coupling deviations

    Rare decay BXsl+lB\to X_sl^+l^- in a CP spontaneously broken two Higgs doublet model

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    The Higgs boson mass spectrum and couplings of neutral Higgs bosons to fermions are worked out i n a CP spontaneously broken two Higgs doublet model in the large tanβ\beta case. The differential branching ratio, forward-backward asymmetry, CP asymmetry and lepton polarization for BXsl+lB\to X_s l^+ l^- are computed. It is shown that effects of neutral Higgs bosons are quite significant when tanβ\tan\beta is large. Especially, the CP violating normal polarization PNP_N can be as large as several percents.Comment: 27 pages, text updated, new numerical results include

    Scales, Couplings Revisited and Low Energy Phenomenology in M-theory on S1/Z2S^1/Z_2

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    We revisit the eleven dimension Planck scale, the physical scale of the eleventh dimension, the physical scale of Calabi-Yau manifold and coupling in hidden sector in M-theory on S1/Z2S^1/Z_2. And we discuss the reasonable bound on them. Considering F-term of dilaton and moduli SUSY breaking and choosing two repersentative points which correspond to scalar quasi-massless scenario and dilaton dominant SUSY breaking scenario respectively, we analyze experimental constraints to the parameter space. The sparticle spectrum and some phenomenological predictions are also given.Comment: 35 pages and 8 eps files. One error on fig1b is correcte

    Bottom Baryons

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    Recently CDF and D0 collaborations observed several bottom baryons. In this work we perform a systematic study of the masses of bottom baryons up to 1/mQ1/m_Q in the framework of heavy quark effective field theory (HQET) using the QCD sum rule approach. The extracted chromo-magnetic splitting between the bottom baryon heavy doublet agrees well with the experimental data.Comment: 8 pages, 5 figures, 3 tables. More discussions and references adde
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