Separated Response Function Ratios in Forward...
27
Separated Response Function Ratios Cornel Butuceanu [email protected] + − π π in Forward Pion Electroproduction APS Meeting, St. Louis, MO, 12-15 April 2008
Transcript of Separated Response Function Ratios in Forward...
Sepa
rate
d Re
spon
se F
unct
ion
Ratios
Corn
el B
utuc
eanu
ccbu
tu@
jlab.
org
+−
ππ
in F
orwa
rd P
ion
Elec
trop
rodu
ction
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 2
008
Jeff
erso
n La
b F π
Colla
bora
tion
R. E
nt, D
. Gas
kell
D. G
aske
ll, M
.K. J
ones
, D. M
ack
D. M
ack,
D. M
eeki
ns, J
. Roc
he, G
. Sm
ith, W
. Vul
can,
G
. War
ren,
S.A
. Woo
dJe
ffers
on L
ab, N
ewpo
rt N
ews,
VA
, USA
C. B
utuc
eanu
,C
. But
ucea
nu,E
.J. B
rash
, G.M
. Hub
erG
.M. H
uber
, V. K
oval
tcho
uk, G
.J. L
olos
, S. V
idak
ovic
, C.
C. X
uXu
Uni
vers
ity o
f Reg
ina,
Reg
ina,
SK,
Can
ada
H.
H. B
lok
Blo
k, V
. Tva
skis
Vrije
Uni
vers
iteit,
Am
ster
dam
, Net
herla
nds
E.
E. B
eise
Bei
se, H
. Bre
uer,
C.C
. Cha
ng, T
. Hor
nT.
Hor
n, P
. Kin
g, J
. Liu
, P.G
. Roo
sU
nive
rsity
of M
aryl
and,
Col
lege
Par
k, M
D, U
SAW
. Boe
glin
, P. M
arko
witz
, J. R
einh
old
Flor
ida
Inte
rnat
iona
l Uni
vers
ity, F
L, U
SAJ.
Arr
ingt
on, R
. Hol
t, D
. Pot
terv
eld,
P. R
eim
er, X
. Zhe
ngAr
gonn
e N
atio
nal L
abor
ator
y, A
rgon
ne, I
L, U
SAH
. Mkr
tchy
an, V
. Tad
evos
yan
Yere
van
Phys
ics
Inst
itute
, Yer
evan
, Arm
enia
S. J
in, W
. Kim
Kyun
gook
Nat
iona
l Uni
vers
ity, T
aegu
, Kor
eaM
.E. C
hris
ty, C
. Kep
pel,
L.G
. Tan
gH
ampt
on U
nive
rsity
, Ham
pton
, VA,
USA
J. V
olm
erD
ESY,
Ham
burg
, Ger
man
yA
. Mat
sum
ura,
T. M
iyos
hi, Y
. Oka
yasu
Tohu
kuU
nive
rsity
, Sen
dai,
Japa
nB
. Bar
rett,
A. S
arty
St. M
ary’
s U
nive
rsity
, Hal
ifax,
NS,
Can
ada
K. A
niol
, D. M
arga
ziot
isC
alifo
rnia
Sta
te U
nive
rsity
, Los
Ang
eles
, CA,
USA
L. P
entc
hev,
C. P
erdr
isat
Col
lege
of W
illia
m a
nd M
ary,
Will
iam
sbur
g, V
A, U
SA
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
Mot
ivat
ion
22
SAVA
SAVA
n)π
p vσ(γ
p)π
n vσ(γ
R+−
=+
→
−→
=
•Tes
ting
the
t-p
ole
dominan
ce �
key
fact
or in
the
extr
action
of
the
pion
form
fac
tor
.
�Pion
elec
trop
rodu
ction
can
proc
eed
via
isov
ecto
ran
d isos
calar
phot
ons.
�Th
e ex
perimen
tal ra
tio
e
volution
with
-t g
ives
a g
ood
indica
tion
of
the
pres
ence
of
isos
calar
proc
esse
s.
�Se
para
ted
ratios
a
nd te
sts
the
t-po
le c
ontr
ibut
ion
to .
± π
LRTR
Lσ
πFt-
pole
q
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
)pp
-e'
H(e
,2
)nn,
e'π
H(e
,2
π+
reac
tion
s
Prev
ious
Stu
dies
1QQ
RR
22
Lππ=
=→
+−
Uns
epar
ated
cros
s se
ction
ratios
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
•At
low
-t
•At
high
-t
A. N
acht
man
n, N
ucl.
Phys
. B 1
15 (1
976)
61
1/4
2Q2QR
R2 u2 d
T=
=→
Expe
rimen
tal Se
tup
Exp
Q2
(GeV
/c)2
W
(GeV
)|t
min|
(Gev
/c)2
E e(G
eV)
Fπ-1
0.6-
1.6
1.6
1.95
0.03
- 0.1
500.
150
2.44
5-4.
045
Fπ-2
1.6
1.6,
2.5
2.22
0.09
30.
093,
0.18
93.
779-
5.24
6
Hall C
spec
trom
eter
s:!
Coincide
nce
mea
sure
men
t.
!SO
S de
tect
s e-
.!
HM
S de
tect
s π+
and
π- .
Targ
ets:
!Liqu
id 4
-cm H
/D c
ells.
!Al (d
ummy)
tar
get
for
back
grou
nd m
easu
remen
t.!
12C
solid
tar
gets
for
opt
ics
calib
ration
.
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
Even
t se
lect
ion
Elec
tron
Elec
tron
-- pion
pion
coincide
nces
coincide
nces
Exclus
ivity
assu
red
via
0.
875<
MM
<1.0
5 Ge
Vcu
t
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
Rand
om
coincide
nces
Pion
sde
tect
ed in
HM
S �
Cere
nkov
&Co
incide
nce
time
for
PID
Elec
tron
s de
tect
ed in
SOS
�Ce
renk
ov&
Lead
Glass
Calor
imet
er
Kine
mat
ics
Kine
mat
ics
Cove
rage
Cove
rage
Take
dat
a at
thr
ee a
ngles:
θ πq=
0o, +4
o , -
4o.
Diamon
d cu
ts d
efine
common
(W,Q
2 )co
vera
ge a
t bo
th ε
.
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
Extr
act
Extr
act σσ LL
by s
imulta
neou
s fit
by s
imulta
neou
s fit
of L
,T,L
T,TTLT
TTσ,
σ
()
φσ
εφ
σε
εσ
σε
φσπ
2co
sco
s1
22
dtddtd
dtddtd
dtdd
TTLT
TL
++
++
=
!M
agne
tic
Calib
ration
s
Ove
rOve
r --co
nstr
aine
d co
nstr
aine
d p(
e,e
p(e,
e ��pp ))
and
elas
tic
and
elas
tic
e +
e +
1212C
reac
tion
s we
reC
reac
tion
s we
reus
ed t
o ca
libra
te s
pect
romet
er a
ccep
tanc
es,
used
to
calib
rate
spe
ctro
met
er a
ccep
tanc
es,
mom
enta
mom
enta
and
and
angu
lar
offs
ets.
angu
lar
offs
ets.
SOS
& HM
S Delta
/xpf
pco
rrelat
ions
wer
e co
rrec
ted
with
a
linea
r de
pend
ent
func
tion
of
form
.
' fpδ
xC
δδ'
⋅+
=
−π
!Co
rrec
tion
s to
the
high
rate
da
ta s
et
data
wer
e ta
ken
at h
igh
rate
s wh
ile da
ta w
ere
take
nat
low
rate
s. U
nder
stan
ding
the
rat
e de
pend
ent
corr
ection
s is v
ery
impo
rtan
t wi
th r
espe
ct t
o th
e fina
l ra
tios
. -N
ew h
igh
rate
tra
cking
algo
rith
m.
-Bet
ter
high
rat
e tr
acking
eff
icienc
ies
(2-9
%).
-HM
S Ce
renk
ovbloc
king
cor
rect
ion
(2-2
0%).
-High
curr
ent
( d
ata
set) t
arge
t bo
iling
cor
rect
ion
(2-1
3%).
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
Dat
a Ana
lysis
+−
ππ/σ
σ
+π
−π
−π
+π
EXIS
TIN
G M
ODEL
S (V
GG &
VGL
)
Pion
elec
trop
rodu
ction
in t
erms
of e
xcha
nge
of π
and
ρRe
gge
traj
ecto
ries
.[V
GL, PR
C 57
(199
8)14
54]
Mod
el p
aram
eter
s fixe
d fr
ompion
phot
opro
duct
ion.
Free
par
amet
ers:
ΛΛπ22
and
ΛΛ ρ22
(( fro
m
from
22H d
ata
H d
ata ))
.
ρex
chan
ge d
oes
not
sign
ifican
tly
influe
nce σ L
at s
mall �t
.
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
VGL
Regg
eM
odel V
GG G
PD M
odel
Pion
elec
trop
rodu
ction
in t
erms
of g
ener
alized
ske
wed
quar
k dist
ribu
tion
s (O
FPD).
[VGG
,PRD
60(
1999
)094
017]
Includ
e po
wer
corr
ection
s du
e to
:
intr
insic
tran
sver
se m
omen
tum
of t
he a
ctive
quar
k
soft
ove
rlap
typ
e co
ntribu
tion
s(n
o gluo
n ex
chan
ge)
Free
par
amet
ers:
ΛΛπ22
and
ΛΛ ρ22
(( fro
m
from
22H d
ata
H d
ata ))
.
12ρ
π,2
2ρ
π,]
/ΛQ
[1)
(QF
−+
=
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
Sepa
rate
d Re
spon
se F
unct
ions
Sepa
rate
d Re
spon
se F
unct
ions
Rat
ios
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
Summar
y�
Sepa
rate
d c
ross
sec
tion
s we
re e
xtra
cted
using
Rose
nbluth
L/T
sepa
ration
tec
hnique
.
�Ra
tios
w
ere
extr
acte
d as
a f
unct
ion
of -
t.
�Pr
elim
inar
y re
sults
show
tha
t is c
onsist
ent
with
1 o
ver
the
whole
rang
e in �
t indica
ting
a d
ominan
ce o
f isov
ecto
rpr
oces
ses
at low
�t
in t
helong
itud
inal r
espo
nse
func
tion
.
�Th
ese
find
ings
con
firm
the
exp
ecta
tion
tha
t is
inde
ed d
ominat
ed b
yth
e t-
pole t
erm.
�In
the
kinem
atic
region
stu
died
her
e bo
th r
atios
an
d pr
esen
t a
very
slig
ht d
epen
denc
e of
.
�Th
e ev
olut
ion
of wi
th �
t sh
ows
a ra
pid
fall
off
which
is c
onsist
ent
with
ear
lier
theo
retica
l pr
ediction
s, e
xpec
ted
to a
ppro
ach
¼, t
he s
quar
eof
the
rat
io o
f th
e qu
ark
char
ges
invo
lved
.
TT
LTT
Lσ,
σ,σ,
σ
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
LR
TR
LR2
QTR
Lσ
Lσ
+−=
ππ
σσR
HM
S Q
3 Co
rrec
tion
s
100
*HM
SP
HM
SP
P
HM
Sδ
' fpx
δC
HM
Sδ
HM
Sδ
−=
∗+
=
Old Q
3/Dipole
ratio
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
SOS
Opt
ics
Calib
ration
For
low
mom
entu
m (<1
.6 G
eV/c
) we
use
d th
e Fp
i1 (19
99) op
tics
mat
rix
& de
lta/
xpfp
corr
ection
.
For
high
mom
entu
m (>1
.6 G
eV/c
) we
use
d th
e Fp
i2 (20
03) ne
w op
tics
mat
rix
& de
lta/
xpfp
corr
ection
.
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
HM
S Ce
renk
ovBl
ocking
CCτeR
1CCε
⋅−
=
!Use
d da
ta t
aken
with
open
trigg
er (el. &
pion
s) t
o fit
the
effe
ctive
time
wind
ow.
!Th
e TD
C time
wind
ow in
Fpi1
is
23%
larg
er t
han
in F
pi2.
!Use
d th
e Fp
i2 d
ata
to f
it t
he e
ffec
tive
TD
C ga
te (fo
r th
e sa
me
CC c
ut).
!Fo
r a
CC c
ut o
f np
e<1.
5 th
e ef
fect
ive
TDC
gate
for
Fpi1
set
is ~
184
ns.
!Im
plies
a larg
er c
orre
ction
for
Fpi1
dat
a
(18-
20 %
at
1MHz)
.
!Si
gnifican
t im
pact
in
pi-
(high
rate
) da
ta.
HM
S CC
TDC
spec
trum
for
e
as ide
ntified
by t
he H
MS
CC A
DC
110102
103
104 -5
00
5010
015
020
025
030
035
040
045
0H
MS
Cer
enko
v T
DC
(n
s)
Fπ-
1N
pe>
0.5
Np
e>2.
0
τ=21
0 n
s
10102
103
104
105 -5
00
5010
015
020
025
030
035
040
045
0H
MS
Cer
enko
v T
DC
(n
s)
Fπ-
2τ=
170
ns
ns 5
184
ττ
R-
1ε
CC
CCe
CC
±=
⋅=
!Unc
erta
inties
ass
ociate
d wi
th t
his
corr
ection
are
of
the
orde
r of
1.6
% a
t 1M
Hz.
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
Corr
ecte
d Tra
cking
Efficien
cies
A ~
8% c
orre
ction
to t
he t
rack
ing
efficien
cies
at
1.4M
Hz
was
applied
to t
he h
igh
rate
dat
a (p
i-).
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
Simulat
ions
vs
Expe
rimen
tal da
ta
Simulat
ed M
issing
Mas
s sp
ectr
um w
as
impr
oved
by
implem
enting
pions
that
wer
e pe
netr
ating
the
collimat
or.
Pion
Punc
hthr
ough
Implem
enta
tion
res
ulte
d in
an o
vera
ll im
prov
ed s
imulat
ed k
inem
atic
variab
les
(W,Q
2,-t
).
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
HM
S Q
3 co
rrec
tion
s
Using
cen
tral H
MS
kine
mat
ics
and
dete
cted
pro
ton
mom
entu
m
we r
econ
stru
ct t
he inv
ariant
mas
s W
(elec
tron
mas
s).
The
W v
sX�d
istr
ibut
ion
was
fitt
ed w
ith
1 de
gree
polyn
omial.
DN
P M
eetin
g, N
N, V
irgin
ia, 1
3 O
ctob
er 2
007
SOS
Q3
Corr
ection
s
2003
SOS
optics
mat
rix
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
Tra
cking
efficien
cy
Two
issu
es:
1.Th
e Fp
i1 v
ersion
of
the
Trk.
Eff
. algo
rith
m u
sed
a ��c
lean
er��
data
sa
mple
by r
emov
ing
the
multiple
hits
ev
ents
res
ulting
in
over
evalua
ted
trk.
ef
f.
2. T
he F
pi2
vers
ion
used
a ��
dirt
y��d
ata
sample
by inc
luding
the
multiple
hits
ev
ents
res
ulting
in
sube
valuat
edtr
k.
eff.
!Th
e high
rat
e da
ta (pi-)
is
the
mos
t se
nsitive
to t
he t
rack
ing
efficien
cy c
orre
ction
(~10
% a
t 1.
4 M
Hz)
.
!A linea
r co
rrec
tion
dep
ende
nt o
f ev
ent
rate
was
app
lied
to t
he
trac
king
eff
icienc
ies
of p
i-da
ta.
Hal
l C U
sers
Mee
ting,
JLa
b, J
anua
ry 1
9, 2
008
SOS
Q3
Corr
ection
s
Low
mom
entu
m (<1
.6 G
eV/c
) �
old
sett
ings
& c
orre
ctions
wo
rks
fine
.
High
mom
entu
m (>1
.6 G
eV/c
) �
use
of n
ew S
OS
optic
mat
rix
& ne
w de
lta/
xpfp
corr
ection
.
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
Tra
cking
Efficien
cy
21
DC
2
22
11
trac
king
P1
Pτ
RP
εP
εP
ε
−=
⋅≈
⋅+
⋅=
0.98
4ε 1=0.
71ε 2=
DC
τ-D
C ga
te w
idth
R �
DC
rate
1P-s
ingle
hit
prob
ability
2P-
multiple
hits
pro
babi
lity
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
HM
S Ce
renk
ovBl
ocking
Using
dat
a ta
ken
with
ope
n tr
igge
r (e
l. &
pions
).
The
TDC
time
wind
ow in
Fpi1
is
23% lar
ger
than
in
Fpi2
.
Use
the
Fpi2
data
to
fit
the
effe
ctive
gate
(sa
me
CC c
ut).
For
npe<
2.0
gate
width
�19
0 ns
.
Implies
a larg
er c
orre
ction
in F
pi1
(18-
20 %
at
1MHz)
.
Sign
ifican
t im
pact
in
pi-
(high
rate
) da
ta.
110102
103
104 -5
00
5010
015
020
025
030
035
040
045
0H
MS
Cer
enko
v TD
C (n
s)
Fπ-1
Npe
>0.5
Npe
>2.0
τ=21
0 ns
10102
103
104
105 -5
00
5010
015
020
025
030
035
040
045
0H
MS
Cer
enko
v TD
C (n
s)
Fπ-2
τ=17
0 ns
CCτeR
1CCε
⋅−
=HM
S CC
TDC
spec
trum
for
e
as ide
ntified
by t
he H
MS
CC A
DC
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
Kine
mat
icVa
riab
les
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
Sepa
rate
d Re
spon
se F
unct
ions
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
Sepa
rate
d Re
spon
se F
unct
ions
Sepa
rate
d Re
spon
se F
unct
ions
Rat
ios
APS
Mee
ting,
St.
Loui
s, M
O, 1
2-15
Apr
il 20
08
cc
butu
@jla
b.or
g
