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the nucleon electromagnetic form factors @xmath2 and @xmath3 are fundamental quantities in nuclear and elementary particle physics as they provide information on the spatial distributions of charge and magnetization within the nucleon . they are a function of the four - momentum transfer squared of the virtual photon , @xmath4 . in the nonrelativistic limit , they are the fourier transform of the charge and magnetization distributions . therefore , isolating the up- and down - quark contributions to the nucleon form factors is essential to examine spatial asymmetries in the quark distributions . there are primarily two methods used to extract the proton form factors . the first is the rosenbluth or longitudinal - transverse ( lt ) separation method  @xcite which uses measurements of unpolarized cross section , and the second is the polarization transfer / polarized target ( pt ) method  @xcite which requires measurements of the spin - dependent cross section . in the one - photon exchange ( ope ) approximation or the born value , the unpolarized cross section is proportional to the `` reduced '' cross section , @xmath5 , where @xmath6 , @xmath7 is the nucleon mass , and @xmath8 is the virtual photon longitudinal polarization parameter defined as @xmath9 $ ] , where @xmath10 is the scattering angle of the electron . measuring @xmath11 at several @xmath8 points for a fixed @xmath4 value , one can separate @xmath12 and @xmath13 . however , for cases where @xmath14 is extremely small ( large ) , it is difficult to extract @xmath12 ( @xmath13 ) with precision . on the other hand , the polarization measurements are sensitive only to the ratio @xmath15 . therefore , by taking ratios of polarization components , many of the systematic uncertainties in the polarization measurements cancel , allowing for precise measurements of the ratio @xmath16  @xcite , where @xmath17 is the proton magnetic dipole moment . the two methods yield strikingly different results for the ratio @xmath18 in the region @xmath19  ( gev / c)@xmath20  @xcite , where the rosenbluth extractions show approximate scaling , @xmath21 , while the recoil polarization data indicate a nearly linear decrease in @xmath18 with @xmath4 with some hint of flattening out above 5 ( gev / c)@xmath20 . recent studies suggest that hard two - photon exchange ( tpe ) corrections to the unpolarized cross section may resolve the discrepancy  @xcite . recent precise measurements of the neutron s electric to magnetic form factor ratio @xmath22 up to 3.4  gev@xmath20  @xcite , combined with existing @xmath16 measurements in the same @xmath4 range allowed for a separation of the up- and down - quark contributions to the nucleon form factors at large @xmath4  @xcite . this first analysis , referred to as `` cjrw '' in this work , examined the scaling behavior of the up- and down - quark contributions at large @xmath4 , supporting the idea that diquark correlations play an important role  @xcite . recently , we extended the flavor separation analysis  @xcite using combined cross section and polarization measurements of elastic electron - proton scattering with an emphasis on precise new data from ref . @xcite covering the low - momentum region , which is sensitive to the large - scale structure of the nucleon . in our work , we account for effects neglected in the original work where we apply tpe corrections in the extraction of the proton form factors based on the approach of ref . the tpe correction applied in our work , based on the parametrization from ref . @xcite , is linear in @xmath8  @xcite and vanishes in the limit @xmath23 1  @xcite . we also compare our results to a parametrization of the proton form factors extracted  @xcite after applying the hadronic calculation for tpe from ref . we also include additional new @xmath24 data from clas  @xcite and performed a new global fit to @xmath24 which we used , along with the parametrization of @xmath25  @xcite , to construct @xmath26 , as well as account for the uncertainties associated with all of the form factors measurements as the cjrw analysis accounted only for uncertainties on @xmath25 which was the dominant uncertainty for their flavor - separated results . finally , we use our results of the flavor - separated form factors to construct the flavor - separated dirac , @xmath27 , and pauli , @xmath28 , form factors and their ratios . in this section , we present our results of the flavor - separated form factors @xmath27 and @xmath28 . we then compare our results to the cjrw extractions which allows for examination of the effect of the tpe corrections applied , additional uncertainties , as well as updated form factor data set used . we also compare our results to the venkat _ et al . _ @xcite ( `` vamz '' ) , and arrington _ et al . _ @xcite ( `` amt '' ) extractions which use improved proton form factor parametrization obtained assuming different treatment of tpe corrections at lower @xmath4 values . in addition , we used the venkat plus the @xmath24 and @xmath25 fits mentioned above , and looked at the impact of our updated @xmath24 fit by replacing this with the kelly  @xcite fit for @xmath24 ( `` vamz - kelly '' ) . finally , we compare the results to recent theoretical calculations and fits to the flavor - separated form factors : a dyson - schwinger equation ( `` dse '' ) calculation  @xcite , a pion - cloud relativistic constituent quark model ( `` pc - rcqm '' )  @xcite , a relativistic constituent quark model whose hyperfine interaction is derived from goldstone - boson exchange ( `` gbe - rcqm '' )  @xcite , and a generalized parton distribution ( gpd ) calculations  @xcite . ( top ) and @xmath28 ( bottom ) and their ratios from our analysis  @xcite and the cjrw extractions  @xcite . also shown are the amt  @xcite and vamz fits  @xcite , and the values from the gbe - rcqm  @xcite , pc - rcqm  @xcite , the dse  @xcite , and the gpd  @xcite models.,title="fig:",width=199 ]    ( top ) and @xmath28 ( bottom ) and their ratios from our analysis  @xcite and the cjrw extractions  @xcite . also shown are the amt  @xcite and vamz fits  @xcite , and the values from the gbe - rcqm  @xcite , pc - rcqm  @xcite , the dse  @xcite , and the gpd  @xcite models.,title="fig:",width=199 ]   ( top ) and @xmath28 ( bottom ) and their ratios from our analysis  @xcite and the cjrw extractions  @xcite . also shown are the amt  @xcite and vamz fits  @xcite , and the values from the gbe - rcqm  @xcite , pc - rcqm  @xcite , the dse  @xcite , and the gpd  @xcite models.,title="fig:",width=199 ] +    ( top ) and @xmath28 ( bottom ) and their ratios from our analysis  @xcite and the cjrw extractions  @xcite . also shown are the amt  @xcite and vamz fits  @xcite , and the values from the gbe - rcqm  @xcite , pc - rcqm  @xcite , the dse  @xcite , and the gpd  @xcite models.,title="fig:",width=199 ]   ( top ) and @xmath28 ( bottom ) and their ratios from our analysis  @xcite and the cjrw extractions  @xcite . also shown are the amt  @xcite and vamz fits  @xcite , and the values from the gbe - rcqm  @xcite , pc - rcqm  @xcite , the dse  @xcite , and the gpd  @xcite models.,title="fig:",width=199 ]    ( top ) and @xmath28 ( bottom ) and their ratios from our analysis  @xcite and the cjrw extractions  @xcite . also shown are the amt  @xcite and vamz fits  @xcite , and the values from the gbe - rcqm  @xcite , pc - rcqm  @xcite , the dse  @xcite , and the gpd  @xcite models.,title="fig:",width=199 ]    figure  [ fig1 ] shows the flavor - separated contributions of @xmath29 and @xmath30 . it was reported in the cjrw analysis that while both the up - quark form factors , @xmath31 and @xmath32 , continued to rise compared to the down - quark , the down - quark contributions , @xmath33 and @xmath34 , strikingly exhibited @xmath35 scaling behavior above @xmath36 1.0 ( gev / c)@xmath20 in agreement with the moments of the generalized parton distributions predictions  @xcite . however , these predictions are based on fits which included nucleon form factors data , except for the most recent @xmath26 data . our results for @xmath31 and @xmath32 suggest as well that both form factors continue to rise with increasing @xmath4 but with @xmath32 values somewhat higher than the cjrw extractions at low @xmath4 . this can be seen clearly in the ratio @xmath37 . on the other hand , our results suggest that the down - quark contributions are falling more rapidly than the up - quark contributions at high @xmath4 with respect to the @xmath35 behavior which is more apparent for @xmath34 and the ratio @xmath37 in agreement with global parametrizations and theoretical calculations which predict faster falloff than the apparent @xmath35 scaling behavior . however , such behavior is sensitive to the parametrization of @xmath26 at @xmath38 2 ( gev / c)@xmath20  @xcite . the difference in the results obtained are attributed mainly to the tpe corrections applied to the proton form factors and to lesser extent to the use of the updated @xmath24 parametrization . in addition , while the @xmath26 uncertainties have the largest impact , the additional uncertainties from the proton and @xmath24 yield a non - negligible increase in the total uncertainties .     and points and curves as in fig . [ fig1].,title="fig:",width=264 ]   and @xmath39 . points and curves as in fig . [ fig1].,title="fig:",width=264 ] +    figure  [ fig2 ] shows the ratios @xmath40 and @xmath39 . here @xmath41 are the @xmath36 0 limits of @xmath42 with @xmath43 1.67 and @xmath44 @xmath45 2.03 . the ratios are scaled by @xmath46 and normalized to @xmath47 yielding 0.5(1 ) for the up(down)-quark contribution . at low @xmath4 , the ratio @xmath48 falls rapidly up to @xmath49 ( gev / c)@xmath20 where it starts to decrease slowly . while our values are somewhat larger than those obtained in the cjrw extractions for @xmath50 1.5 ( gev / c)@xmath20 due to the difference in the @xmath32 values , they are in good qualitative agreement with form factor fits and calculations . the ratio @xmath39 increases slowly at low @xmath4 and becomes almost constant for @xmath38 1 ( gev / c)@xmath51 . our results are consistent with both the cjrw results and extractions based on form factors fits . however , our results differ from all calculations as they predict a rapid falloff of @xmath33 at large @xmath4 compared to @xmath34 which clearly leads to a rapid rise in the ratio . the high-@xmath4 measurements of @xmath26 planned at jefferson lab after the 12 gev upgrade  @xcite are clearly critical to pin down the behavior of this ratio as well as to examine the theoretical calculations and models . this work was supported by khalifa university of science , technology and research and by the u.s . department of energy , office of nuclear physics , under contract de - ac02 - 06ch11357 . 30 rosenbluth m n 1950 _ phys . rev . _ * 79 * 615 dombey n 1969 _ rev . phys . _ * 41 * 236 punjabi v _ et al . _ 2005 _ phys . * c71 * 055202 ; puckett a j r _ et al . _ 2012 _ phys . rev . _ * c85 * 045203 ; puckett a j r _ et al . _ 2010 _ phys . lett . _ * 104 * 242301 ; zhan x _ et al . _ 2011 _ phys . lett . _ * b705 * 59 ; ron g _ _ 2011 _ phys . rev . _ * c84 * 055204 ; arrington j , perdrisat c , and de jager c w 2011 _ j. phys . conf . ser . _ * 299 * 012002 qattan i a _ et al . _ 2005 _ phys . lett . _ * 94 * 142301 ; arrington j 2003 _ phys . * c68 * 034325 arrington j , melnitchouk w , and tjon j a 2007 _ phys . rev . _ * c76 * 035205 carlson c e and vanderhaeghen m 2007 _ ann nucl . part . sci . _ * 57 * 171 arrington j , blunden p , and melnitchouk w 2011 _ prog . phys . _ * 66 * 782 qattan i a and alsaad a 2011 _ phys * c84 * 054317 [ erratum : 2011 _ phys . * c84 * 029905 ] adikaram d _ ( clas collaboration ) 2015 _ phys . lett . _ * 114 * 062003 ; rachek i a _ et al . _ 2015 _ phys . _ * 114 * 062005 ; rimal d _ et al . _ ( clas collaboration ) 2016 _ preprint _ arxiv:1603.00315 [ nucl - ex ] blunden p g , melnitchouk w , and tjon j a 2005 _ phys . * c72 * 034612 riordan s _ et al . _ 2010 _ phys . lett . _ * 105 * 262302 cates g , de jager c , riordan s , and wojtsekhowski b 2011 _ phys . rev * 106 * 252003 cloet i _ et al . _ 2009 _ few - body syst . _ * 1 qattan i a and arrington j 2012 _ phys . rev . _ * c86 * 065210 qattan i a and arrington j 2014 _ eur . j. woc _ * 66 * 06020 qattan i a , arrington j , and alsaad a 2015 _ phys . _ * c91 * 065203 bernauer j c _ et al . _ ( a1 collaboration ) 2014 _ phys . * c90 * 015206 qattan i a , alsaad a , and arrington j 2011 _ phys . * c84 * 054317 borisyuk d and kobushkin a 2011 _ phys . * d83 * 057501 tvaskis v _ et al . _ 2006 _ phys . _ * c73 * 025206 arrington j , blunden p g , and melnitchouk w 2011 _ prog . phys . _ * 66 * 782 ; chen y -c , kao c -w , and yang s -n 2007 _ phys . lett . _ * b652 * 269 arrington j 2004 _ phys . rev . _ * c69 * 032201 lachniet j _ et al . _ ( clas collaboration ) 2009 _ phys . lett . _ * 102 * 192001 venkat s , arrington j , miller g a , and zhan x 2011 _ phys . rev . _ * c83 * 015203 kelly j j 2004 _ phys * c70 * 068202 cloet i c and miller g a 2012 _ phys . rev . _ * c86 * 015208 rohrmoser m , choi k -s , and plessas w 2011 _ preprint _ arxiv:1110.3665 [ hep - ph ] gonzalez - hernandez j o , liuti s , goldstein g r , and kathuria k 2013 _ phys * c88 * 065206 diehl m , feldmann t , jakob r , and kroll p 2005 _ eur . phys . j. _ * c39 * 1 dudek j _ _ 2012 _ eur . phys . j. _ * a48 * 187
the spatial distribution of charge and magnetization within the nucleon ( proton and neutron ) is encoded in the elastic electromagnetic form factors @xmath0 and @xmath1 . 
 these form factors have been precisely measured utilizing elastic electron scattering , and the combination of proton and neutron form factors allows for the separation of the up- and down - quark contributions to the nucleon form factors . 
 we expand on our original analyses and extract the up- and down - quark contributions to the nucleon electromagnetic form factors from worldwide data with an emphasis on precise new data covering the low - momentum region , which is sensitive to the large - scale structure of the nucleon . from these , we construct the flavor - separated dirac and pauli form factors and their ratios , and compare the results to recent extractions and theoretical calculations and models .