Determination of the pion charge form factor at Q2=1.60 and 2.45 (GeV/c)2.
نویسندگان
چکیده
The 1H(e,e'pi+)n cross section was measured at four-momentum transfers of Q2=1.60 and 2.45 GeV2 at an invariant mass of the photon nucleon system of W=2.22 GeV. The charged pion form factor (F(pi)) was extracted from the data by comparing the separated longitudinal pion electroproduction cross section to a Regge model prediction in which F(pi) is a free parameter. The results indicate that the pion form factor deviates from the charge-radius constrained monopole form at these values of Q2 by one sigma, but is still far from its perturbative quantum chromodynamics prediction.
منابع مشابه
Measurement of the charged pion electromagnetic form factor.
Separated longitudinal and transverse structure functions for the reaction 1H(e,e(')pi(+))n were measured in the momentum transfer region Q2 = 0.6--1.6 (GeV/c)(2) at a value of the invariant mass W = 1.95 GeV. New values for the pion charge form factor were extracted from the longitudinal cross section by using a recently developed Regge model. The results indicate that the pion form factor in ...
متن کاملPion structure from improved lattice QCD: form factor and charge radius at low masses
The charge form factor of the pion is calculated in lattice QCD. The non-perturbatively improved Sheikholeslami-Wohlert action is used together with the O(a) improved vector current. Other choices for the current are examined. The form factor is extracted for pion masses from 970 MeV down to 360 MeV and for momentum transfers Q2 ≤ 2 GeV. The mean square charge radius is extracted, compared to p...
متن کاملHELICITY AND PLANAR AMPLITUDES IN PION-PROTON SCATTERING AT 6.0 GeV/c
In addition to optimal conditions, invariant laws of Lorentz, parity and time reversal are imposed to find the relation between observables (spin rotation parameters) and bilinear combination of helicity amplitudes in pion-proton elastic scattering at 6.0 GeV/c. By normalizing the differential cross-section to unity, the magnitudes of helicity amplitudes and the angle between them are dete...
متن کاملAnalytic coupling and Sudakov effects in exclusive processes : pion and γ ∗ γ → π 0 form factors
We develop and discuss in technical detail an infrared-finite factorization and optimized renormalization scheme for calculating exclusive processes, which enables the inclusion of transverse degrees of freedom without entailing suppression of calculated observables, like form factors. This is achieved by employing an analytic, i.e., infrared stable, running strong coupling αs(Q) which removes ...
متن کاملThe pion’s electromagnetic form factor at small momentum transfer in full lattice QCD
We compute the electromagnetic form factor of a “pion” with mass mπ = 330MeV at low values of Q2 ≡ −q2, where q is the momentum transfer. The computations are performed in a lattice simulation using an ensemble of the RBC/UKQCD collaboration’s gauge configurations with Domain Wall Fermions and the Iwasaki gauge action with an inverse lattice spacing of 1.73(3)GeV. In order to be able to reach l...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Physical review letters
دوره 97 19 شماره
صفحات -
تاریخ انتشار 2006