118681007
Endpoint behavior of high-energy scattering cross sections
In high-energy processes near the endpoint, there emerge new contributions associated with spectator interactions. Away from the endpoint region, these new contributions are suppressed compared to the leading contribution, but the leading contribution becomes suppressed as we approach the endpoint and the new contributions become comparable. We present how the new contributions scale as we reach the endpoint and show that they are comparable to the suppressed leading contributions in deep inelastic scattering by employing a power-counting analysis. The hadronic tensor in deep inelastic scattering is shown to factorize including the spectator interactions, and it can be expressed in terms of the light cone distribution amplitudes of initial hadrons. We also consider the contribution of the spectator contributions in Drell-Yan processes. Here the spectator interactions are suppressed compared to double parton annihilation according to the power counting.
118701906
Nonperturbative charming penguin contributions to isospin asymmetries in radiative B decays
Recent experimental data on the radiative decays B{yields}V{gamma}, where V is a light vector meson, find small isospin violation in B{yields}K*{gamma} while isospin asymmetries in B{yields}{rho}{gamma} are of order 20%, with large uncertainties. Using soft-collinear effective theory, we calculate isospin asymmetries in these radiative B decays up to O(1/m{sub b}), also including O(v{alpha}{sub s}) contributions from nonperturbative charming penguins (NPCP). In the absence of NPCP contributions, the theoretical predictions for the asymmetries are a few percent or less. Including the NPCP can significantly increase the isospin asymmetries for both B{yields}V{gamma} modes. We also consider the effect of the NPCP on the branching ratio and CP asymmetries in B{sup {+-}}{yields}V{sup {+-}}{gamma}.
32115869
Factorization theorem for high-energy scattering near the end point.
A consistent factorization theorem is presented in the framework of effective field theories. Conventional factorization suffers from infrared divergences in the soft and collinear parts. We present a factorization theorem in which the infrared divergences appear only in the parton distribution functions by carefully reorganizing collinear and soft parts. The central idea is extracting the soft contributions from the collinear part to avoid double counting. Combining it with the original soft part, an infrared-finite kernel is obtained. This factorization procedure can be applied to various high-energy scattering processes.
118447534
Proper factorization theorems in high-energy scattering near the endpoint
A bstractConsistent factorization theorems in high-energy scattering near the threshold are presented in the framework of the soft-collinear effective theory. Traditional factorization theorem separates the soft and collinear parts successfully, but a final step should be supplemented if each part encounters infrared divergence. We present factorization theorems in which the infrared divergences appear only in the parton distribution functions and the infrared divergence is removed by carefully separating and reorganizing collinear and soft parts. The underlying physical idea is to isolate and remove the soft contributions systematically from the collinear part in loop corrections order by order. After this procedure, each factorized term in the scattering cross sections is free of infrared divergence, and can be safely computed using perturbation theory. This factorization procedure can be applied to various high-energy scattering processes. We show factorization theorems in Drell-Yan processes, deep inelastic scattering and Higgs production near the endpoint.
8812146
Rare radiative exclusive B decays in soft-collinear effective theory
We consider rare radiative B decays such as $\overline{B}\ensuremath{\rightarrow}{K}^{*}\ensuremath{\gamma}$ or $\overline{B}\ensuremath{\rightarrow}\ensuremath{\rho}\ensuremath{\gamma}$ in soft-collinear effective theory (SCET) and show that the decay amplitudes are factorized to all orders in ${\ensuremath{\alpha}}_{s}$ and at leading order in ${\ensuremath{\Lambda}}_{\mathrm{QCD}}{/m}_{b}.$ By employing two-step matching, we classify the operators for radiative B decays in powers of a small parameter $\ensuremath{\lambda}(\ensuremath{\sim}\sqrt{{\ensuremath{\Lambda}}_{\mathrm{QCD}}{/m}_{b}})$ and obtain the relevant operators to order $\ensuremath{\lambda}$ in ${\mathrm{SCET}}_{\mathrm{I}}.$ These operators are constructed with or without spectator quarks including the four-quark operators contributing to annihilation and W-exchange channels. And we employ ${\mathrm{SCET}}_{\mathrm{II}}$ where the small parameter becomes of order ${\ensuremath{\Lambda}}_{\mathrm{QCD}}{/m}_{b},$ and evolve the operators in order to compute the decay amplitudes for rare radiative decays in soft-collinear effective theory. We show explicitly that the contributions from the annihilation channels and the W-exchange channels vanish at leading order in SCET. We present the factorized result for the decay amplitudes in rare radiative B decays at leading order in SCET and at next-to-leading order in ${\ensuremath{\alpha}}_{s}.$
13093742
Semi-inclusive hadronic B decays in the endpoint region
We consider in the soft-collinear effective theory semi-inclusive hadronic $B$ decays, $B\ensuremath{\rightarrow}XM$, in which an energetic light meson $M$ near the endpoint recoils against an inclusive jet $X$. We focus on a subset of decays where the spectator quark from the $B$ meson ends up in the jet. The branching ratios and direct $CP$ asymmetries are computed to next-to-leading order accuracy in ${\ensuremath{\alpha}}_{s}$ and to leading order in $1/{m}_{b}$. The contribution of charming penguins is extensively discussed, and a method to extract it in semi-inclusive decays is suggested. Subleading $1/{m}_{b}$ corrections and $SU(3)$ breaking effects are discussed.
109775896
Results of radiation test of the cathode front-end board for CMS endcap muon chambers
Abstract After a brief overview of the CMS EMU electronics system, results on radiation induced single event effects, total ionization dose and displacement effects will be reported. These results are obtained by irradiating the components on electronics boards with 63 MeV protons and 1 MeV neutrons. During the proton irradiation, the electronics board was fully under power, all components on the board were active and the data were read out in the same way as designed for CMS. No deterioration of analog performance for each of the three CMOS ASICs on the tested board was observed, up to a dose of 10 krad . Each of the tested FPGAs survived beyond the dose of 30 krad . No single event latch-up was detected for the CMOS ASICs up to a proton fluence of 2×10 12 cm −2 . Single Event Upsets (SEU) in FPGAs were detected and their cross-sections measured. SEU mitigation with triple module redundancy and voting was implemented and tested.