the low energy physics frontier of the standard model at the mami accelerator

Concettina SfientiJohannes Gutenberg-Universität - Institut für Kernphysik, Mainz

The low energy physics frontier

@Mami:Results and Perspectives

Sunday, April 13, 2014

Why? How?

Who? Where?




EU-DE-MZ-JGU-KPH


The MAMI Legacy


Upgrade to ...

MAMI-C Harmonic Double Sided Microtron (2007)up to E = 1.6 GeV

HIGH Intensity up to 100 µA

Resolution σE < 0.100 MeV

Polarization up to 80% @ 40µA

Reliability 85% (7000 h/y)

The MAMI Legacy


The Wheelers

!"!"#$%&'()*"+&,-%(.*/"

01(%%"#$%&'()*+,-.+/"23%&'()4%'%(+"

01213'"456'78#9'


The Wheelers

!"!"#$%&'()*"+&,-%(.*/"

01(%%"#$%&'()*+,-.+/"23%&'()4%'%(+"

01213'"456'78#9'

!"#$%&'($)*+,+-$./'0&12-3!

! $!"##$%&41&566,1'*(78)*+,+-6$

! !"#8.&,9:#$;1<6,'($4'((=$>!).$


The Wheelers

!"!"#$%&'()*"+&,-%(.*/"

01(%%"#$%&'()*+,-.+/"23%&'()4%'%(+"

01213'"456'78#9'

!"#$%&'($)*+,+-$./'0&12-3!

! $!"##$%&41&566,1'*(78)*+,+-6$

! !"#8.&,9:#$;1<6,'($4'((=$>!).$

!"#$%&'()*$+(,-&.,/$(/$(/$01$0-&2.3$23&40'(/5$!"#$%&'!("#')*+,,&-."&*/012'3$

! $%678$9&-,'(:0)0'$$


The Realm


The Middle Earth of the Nuclear Realm

LRP Nuclear Science Advisory Committee(2008)

Res

olut

ion

Complexity

Simplicity Hot and dense quark-gluon matter

Hadron structure

Nuclear structure Nuclear reactions

Nuclear astrophysics

Applications of nuclear science

Hadron-Nuclear interface


What is it all about?


Scales and Phases of Nuclear Matter

Courtesy R.F.Carsten (WNSL)

LOOKING INWARD

NucleonNuclear

StructureNuclear

AstrophysicsNeutron

Stars HypernucleiHot and Dense Matter

OUTWARD LOOKING


First Constraint

„If the Lord Almighty had consulted me before embarking upon creation, I would have recommended something simpler.“King Alphonse X. of Castille and Léon (1221-1284), on having the Ptolemaic system of epicycles explained to him

QCD in the non-perturbative

regimeF. Wilczek “QCD made simple” (http://www.frankwilczek.com/)


http://www.frankwilczek.com/Wilczek_Easy_Pieces/298_QCD_Made_Simple.pdf

http://www.frankwilczek.com/Wilczek_Easy_Pieces/298_QCD_Made_Simple.pdf

First Constraint

Modern nuclearphysics is about...

!Linking QCD to many body systems

UNEDF SciDAC CollaborationUniversal Nuclear Energy Density Functional


The Beauty of the Electromagnetic Probe

Clean probe of hadron structure

" Electron-vertex well-known from QED

" One-photon exchange dominates

" Higher-order exchange diagrams are suppressed

" Vary the wavelength of the probe to view deeper inside the hadron


The Proton


The Proton

...ask Prof. Wiki


The Proton

Mass

(M

eV

)

One Millennium Quest

Generation of Mass Not the elementary mass of the fermions

! Higgs Sector

But the actual mass of the “Macroscopic” Hadron and its Composites


Nuclear Physics @ A=1 ≡ Nucleon PropertiesIntroduction – Nucleon properties

Proton / Neutron

mass

mp = 938.272046(21)MeV/c2

Discovered by E. Rutherford (1919)

mn = 939.565379(21)MeV/c2

Discovered by J. Chadwick (1939)

size

moments of electric chargeand magnetization distributionderived fromform factor measurements

shape

departure fromspherical symmetrydetermined in N −→ ∆

measurements

stiffness

electric and magneticpolarizabilities extracted fromVirtual Compton scattering(VCS)


“ Diamonds are for ever ...



Form Factors are e!ernal ”http://hyperphysics.phy-astr.gsu.edu/

Rutherford Scattering

+ relativistic electrons + nuclear recoil + magnetic moments = Mott Scattering


http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html



Form Factors are e!ernal ”http://hyperphysics.phy-astr.gsu.edu/

Rutherford Scattering

+ relativistic electrons + nuclear recoil + magnetic moments = Mott Scattering

Hofstadter, R., et al., Phys. Rev. 92, 978 (1953).

!

d"d#

=d"d#$

% &

'

( ) Mott

* G(q) 2




Form Factors from Elastic ep scatteringClassical picture

form factor: G(q2) = 1e

� ∞

0ρ(r)

sin qrqr

4πr2 dr

dipolee.g. proton

form

fact

or |G

(q2 )|

!

gaussiane.g. 6Li

momentum transfer |q| !

oscillatinge.g. 40Ca

Fourier

⇔

Transform

exponential

char

ge d

ensi

ty !

(r) "

gaussian

radius r "

sphere withdiffuse edge

charge distribution: ρ(r) = e(2π)3

� ∞

0G(q2)

sin qrqr

4πq2 dq


Cross section for one photon exchange (Rosenbluth-cross section + Separation at constant Q2)

... and the slope of GE

charge distribution

distribution of magnetic moments

# Separated GE(Q2) and GM(Q2)$ but contribution from two photon exchange (TPE)

Form Factors from Elastic ep scattering


● Statistical precision σ < 0.1% ● δθ < 0.5 mrad vertical and horizontal● Control of luminosity and systematic errors

The latest MAMI measurement

The experiment designed for ...high precision by redundancy

% All quantities measured by more than one method


Rosenbluth with a twist

“Super-Rosenbluth Separation”: fit of form factor models DIRECTLY to cross sections

● All Q2 and ε data are used in one fit● No projection to constant Q2

% no limit of kinematics● One “estimator”

% stat. theory “robust estimator”


Strong InteractionsHadron Structure

Hadron Spectroscopy

High-Energy PhysicsPrecision PhysicsAtomic Physics

Astrophysics

The Low Energy Frontier

!"#$%&'&(#)*+%,-#

%+./01

...theAtomic Physics

frontierSunday, April 13, 2014

The Low Energy FrontierThe radius puzzle – Lamb shift in µH

Nature 466, 213-216 (8 July 2010)


“WE are famous!” (ED)

! !

!!"#$%#!&'()*+,

!!-).!/*+.!01.#%#+.0123

"!4#+.+!)*%!.5#)%#.06'7!*18#%+.'18012!)&!9%).)1

"!:'80*+!)&!9%).)1!0+!8)(01'1.!*16#%.'01.;!01!('1;!<=>!9%)6#++#+!

! !

!!"#$%#!&'()*+,

!!-).!/*+.!01.#%#+.0123

"!4#+.+!)*%!.5#)%#.06'7!*18#%+.'18012!)&!9%).)1

"!:'80*+!)&!9%).)1!0+!8)(01'1.!*16#%.'01.;!01!('1;!<=>!9%)6#++#+!

....not just interesting:& Tests our theoretical understanding of proton& Radius of proton is dominant uncertainty in many QED processes


R. Pohl et al., Nature 466, (2010) 213

The Radius Puzzle

Discrepancy is between muonic and electronic measurements



The Radius Puzzle


Proton Radius Puzzle 57

muonichydrogen

1962

1963

1974

1980

1994

1996

1997

1999

2000

2001

2003

2007

2008

2010

2011

0.780

0.800

0.820

0.840

0.860

0.880

0.900

0.920

Orsay, 1962Stanford, 1963Saskatoon, 1974Mainz, 1980Sick, 2003Hydrogen

Dispersion fitCODATA 2006MAMI, 2010JLab, 2011Sick, 2011CODATA 2010

year !Pr

oton

radi

us (f

m)

Figure 1: Proton radius determinations over time. Electronic measurements seem

to settle around rp=0.88 fm, whereas the muonic hydrogen value [1,2] is at 0.84 fm.

Values are (from left to right): Orsay [10], Stanford [11], Saskatoon [12, 13],

Mainz [14] (all in blue) are early electron scattering measurements. Recent new

scattering measurements are from MAMI [4] and Jlab [15]. The green and cyan

points denote various reanalyses of the world electron scattering data [16–21]. The

red symbols originate from laser spectroscopy of atomic hydrogen and advances

in hydrogen QED theory (see [3] and references therein). The green and red

points in the year 2003 denote the reanalysis of the world electron scattering

data [19] and the world data from hydrogen and deuterium spectroscopy which

have determined the value of rp in the CODATA adjustments [3, 22] since the

2002 edition.

Pohl, Gilman, Miller, Pachucki review, arXiv:1301.0905,

Novel beyond SM physics?Novel hadron physics?already excluded: missing atomic physics, structures in FF, anomalous 3rd Zemach radius



The Radius Puzzle


New data are needed and they are coming ...

Harald Merkel, European Few Body 22, Krakow 09/2013

Possible Improvements on Proton Radius

Range of new experiment

Belushkin (Dispersion Analysis 2007)Price (CEA 1971)Murphy (Saskatoon 1974)Borkowski (MAMI 1975)Simon (MAMI 1980)Bernauer (MAMI 2010)

Four-Momentum Transfer Q2 / (GeV2/c2)E

lect

ricFo

rmFa

ctor

Gp E/G

Dip

ole

0.10.010.0010.0001

1.02

1.01

1

0.99

0.98

0.97

0.96

Where should we determine the root-mean-square-radius?

�r2E�= −6

ddQ2 GE(Q2)

��Q2=0

Extrapolation to Q2 = 0, no absolute cross section!

Sufficient “Lever arm” for radius determination → Q2 ≈ 0.2GeV2/c2

Reduction of higher orders → linear fit

...where should we determine the root-mean-square-radius?

Extrapolation ! No absolute cross sectionSunday, April 13, 2014

Possible experiments include:

Redoing atomic hydrogen

Light muonic atoms for radius comparison in heavier systems

Electron scattering at lower Q2 (JLAB, MAMI)

Muon scattering (MUSE@PSI)

Improvements on Proton Radius


The Proton Radius Puzzle


Second constraint

© Jens Rydén

© Corgi Lane

© ryandury

It’s always just water


Second constraint

© CERN © NASA

It’s always just nuclear matter

© SciencePhotoLibrary


Second constraint

It’s always just nuclear matter


Second constraint

Modern nuclearphysics is about...

!Unravelling the phases of nuclear matter

LRP Nuclear Science Advisory Committee(2008)


Second constraint

Each PHASE can exist in a variety of states.

Each STATE is characterized by defined properties


Second constraint

Each PHASE can exist in a variety of states.

Each STATE is characterized by defined properties

The EOS summarizes the physically possible combination of states.

PV = nRT


A heavy nucleus (like 208Pb) is 18 orders of magnitude smaller and 55 orders of magnitude lighter than a neutron star

Yet bounded by the same EOS

The Equation of State of Nuclear Matter

© NASA

© SciencePhotoLibrary



Hadron Spectroscopy


Astrophysics


...theAstrophysics

frontier

!"#$%&'()*+&&!,-.(,"


Where do the neutrons go?

Pressure forces neutrons out against surface tension

EOS

Neutron Skin Measurements


PV: the view in the mirror

!"#$%&'(#) !*+,#-./0 1111/./././.1111

234&56234&56234&56234&56 7&8(35&897&8(35&897&8(35&897&8(35&89:#:#:#:#5%'5%'5%'5%' 7&';7&';7&';7&'; &9#&9#&9#&9#5%'5%'5%'5%' <&4484<&4484<&4484<&4484!"!#$%&' (#)$$!%*'+,

#-)'+! -!"*#*$. &/01!)2 #-)'+! &/03)%*$.

2!)(4%! )(.22!$%.,

!"!#$%*# #-)%+! 5 6

7!)8 #-)%+! !696: 5

Non-PV e-scatteringElectron scattering γ exchange provides Rp through nucleus FFs


!"#$%&'(#) !*+,#-./0 1111/./././.1111

234&56234&56234&56234&56 7&8(35&897&8(35&897&8(35&897&8(35&89:#:#:#:#5%'5%'5%'5%' 7&';7&';7&';7&'; &9#&9#&9#&9#5%'5%'5%'5%' <&4484<&4484<&4484<&4484!"!#$%&' (#)$$!%*'+,

#-)'+! -!"*#*$. &/01!)2 #-)'+! &/03)%*$.

2!)(4%! )(.22!$%.,

!"!#$%*# #-)%+! 5 6

7!)8 #-)%+! !696: 5


!"#$%&'(#) !*+,#-./0 1111/./././.1111

234&56234&56234&56234&56 7&8(35&897&8(35&897&8(35&897&8(35&89:#:#:#:#5%'5%'5%'5%' 7&';7&';7&';7&'; &9#&9#&9#&9#5%'5%'5%'5%' <&4484<&4484<&4484<&4484!"!#$%&' (#)$$!%*'+,

#-)'+! -!"*#*$. &/01!)2 #-)'+! &/03)%*$.

2!)(4%! )(.22!$%.,

!"!#$%*# #-)%+! 5 6

7!)8 #-)%+! !696: 5


PV e-scatteringElectron also exchange Z, which is parity violatingPrimarily couples to neutron



!"#$%&'(#) !*+,#-./0 1111/./././.1111

234&56234&56234&56234&56 7&8(35&897&8(35&897&8(35&897&8(35&89:#:#:#:#5%'5%'5%'5%' 7&';7&';7&';7&'; &9#&9#&9#&9#5%'5%'5%'5%' <&4484<&4484<&4484<&4484!"!#$%&' (#)$$!%*'+,

#-)'+! -!"*#*$. &/01!)2 #-)'+! &/03)%*$.

2!)(4%! )(.22!$%.,

!"!#$%*# #-)%+! 5 6

7!)8 #-)%+! !696: 5


PV e-scatteringElectron also exchange Z, which is parity violatingPrimarily couples to neutronDetectable in PV asymmetry of electrons with different helicity

!"#$%&'(#) !*+,#-./0 1111/./././.1111

234&56234&56234&56234&56 7&8(35&897&8(35&897&8(35&897&8(35&89:#:#:#:#5%'5%'5%'5%' 7&';7&';7&';7&'; &9#&9#&9#&9#5%'5%'5%'5%' <&4484<&4484<&4484<&4484!"!#$%&' (#)$$!%*'+,

#-)'+! -!"*#*$. &/01!)2 #-)'+! &/03)%*$.

2!)(4%! )(.22!$%.,

!"!#$%*# #-)%+! 5 6

7!)8 #-)%+! !696: 5

Parity Violating Electron Scattering

e− also exchange Z , which is parityviolating

Primarily couples to neutron:

Qprotonweak ∝ 1− 4 sin2 θW ≈ 0.076, Qneutron

weak ∝ −1

e!

Z

Detectable in parity violating asymmetry of electrons withdifferent helicity

In Born approximation, Q2 � M2Z , from γ − Z interference:

APV =σ+ − σ−

σ+ + σ− =GFQ2

4πα√2

�1− 4 sin2 θW − Fn(Q2)

Fp(Q2)

�

For fixed target exp., typical APV ∼ 10−7 − 10−4

Seamus Riordan — CREX 2013 PREX 5/19


Hard, harder, PV Experiments3 Decades of Progess

sub-part per billion statistical reach and systematic controlsub-1% normalization control

State-of-the-art:


Hard, harder, PV Experiments

sub-part per billion statistical reach and systematic controlsub-1% normalization control

State-of-the-art:3 Decades of Progess

Roca-Maza et al

± 3%

± 0.06 fmPV Measurements@A1(commissioning in Spring 2014 - 12C)


Diverse experiments but consistent results

Too many model dependent observables

Neutron skin Radii: Where are we?

Precise determination of NSkin in 208Pb set a basic constraint on the nuclear symmetry energy

does not. Then, we have to conclude that a 3% accuracy inAPV sets modest constraints on L, implying that some ofthe expectations that this measurement will constrain Lprecisely may have to be revised to some extent. To narrowdown L, though demanding more experimental effort, a!1% measurement of APV should be sought ultimately inPREX. Our approach can support it to yield a new accuracynear !!rnp ! 0:02 fm and !L! 10 MeV, well below anyprevious constraint. Moreover, PREX is unique in that thecentral value of !rnp and L follows from a probe largelyfree of strong force uncertainties.

In summary, PREX ought to be instrumental to pave theway for electroweak studies of neutron densities in heavynuclei [9,10,26]. To accurately extract the neutron radiusand skin of 208Pb from the experiment requires a preciseconnection between the parity-violating asymmetry APV

and these properties. We investigated parity-violating elec-tron scattering in nuclear models constrained by availablelaboratory data to support this extraction without specificassumptions on the shape of the nucleon densities. Wedemonstrated a linear correlation, universal in the meanfield framework, between APV and!rnp that has very smallscatter. Because of its high quality, it will not spoil theexperimental accuracy even in improved measurements ofAPV. With a 1% measurement of APV it can allow one toconstrain the slope L of the symmetry energy to near anovel 10 MeV level. A mostly model-independent deter-mination of !rnp of 208Pb and L should have enduringimpact on a variety of fields, including atomic paritynonconservation and low-energy tests of the standardmodel [8,9,32].

We thank G. Colo, A. Polls, P. Schuck, and E. Vivesfor valuable discussions, H. Liang for the densities ofthe RHF-PK and PC-PK models, and K. Kumar for infor-mation on PREX kinematics. Work supported by theConsolider Ingenio Programme CPAN CSD2007 00042

and Grants No. FIS2008-01661 from MEC and FEDER,No. 2009SGR-1289 from Generalitat de Catalunya, andNo. N N202 231137 from Polish MNiSW.

[1] Special issue on The Fifth International Conference onExotic Nuclei and Atomic Masses ENAM’08, edited byM. Pfutzner [Eur. Phys. J. A 42, 299 (2009)].

[2] G.W. Hoffmann et al., Phys. Rev. C 21, 1488 (1980).[3] J. Zenihiro et al., Phys. Rev. C 82, 044611 (2010).[4] A. Krasznahorkay et al., Nucl. Phys. A731, 224 (2004).[5] B. K!os et al., Phys. Rev. C 76, 014311 (2007).[6] E. Friedman, Hyperfine Interact. 193, 33 (2009).[7] T.W. Donnelly, J. Dubach, and Ingo Sick, Nucl. Phys.

A503, 589 (1989).[8] D. Vretenar et al., Phys. Rev. C 61, 064307 (2000).[9] C. J. Horowitz, S. J. Pollock, P. A. Souder, and R.

Michaels, Phys. Rev. C 63, 025501 (2001).[10] K. Kumar, P. A. Souder, R. Michaels, and G.M. Urciuoli,

http://hallaweb.jlab.org/parity/prex (see section ‘‘Statusand Plans’’ for latest updates).

[11] M. Centelles, X. Roca-Maza, X. Vinas, and M. Warda,Phys. Rev. C 82, 054314 (2010).

[12] I. Angeli, At. Data Nucl. Data Tables 87, 185 (2004).[13] B. A. Brown, Phys. Rev. Lett. 85, 5296 (2000); S. Typel

and B.A. Brown, Phys. Rev. C 64, 027302 (2001).[14] R. J. Furnstahl, Nucl. Phys. A706, 85 (2002).[15] A.W. Steiner, M. Prakash, J.M. Lattimer, and P. J. Ellis,

Phys. Rep. 411, 325 (2005).[16] B. G. Todd-Rutel and J. Piekarewicz, Phys. Rev. Lett. 95,

122501 (2005).[17] M. Centelles, X. Roca-Maza, X. Vinas, and M. Warda,

Phys. Rev. Lett. 102, 122502 (2009); M. Warda, X. Vinas,X. Roca-Maza, and M. Centelles, Phys. Rev. C 80, 024316(2009).

[18] A. Carbone et al., Phys. Rev. C 81, 041301(R) (2010).[19] L.W. Chen et al., Phys. Rev. C 82, 024321 (2010).[20] B. A. Li, L.W. Chen, and C.M. Ko, Phys. Rep. 464, 113

(2008).[21] M. B. Tsang et al., Phys. Rev. Lett. 102, 122701 (2009).[22] C. J. Horowitz and J. Piekarewicz, Phys. Rev. Lett. 86,

5647 (2001).[23] J. Xu et al., Astrophys. J. 697, 1549 (2009).[24] A.W. Steiner, J.M. Lattimer, and E. F. Brown, Astrophys.

J. 722, 33 (2010).[25] O. Moreno, E. Moya de Guerra, P. Sarriguren, and J.M.

Udıas, J. Phys. G 37, 064019 (2010).[26] S. Ban, C. J. Horowitz, and R. Michaels, arXiv:1010.3246.[27] N. R. Draper and H. Smith, Applied Regression Analysis

(Wiley, New York, 1998), 3rd ed.[28] K. Hebeler, J.M. Lattimer, C. J. Pethick, and A. Schwenk,

Phys. Rev. Lett. 105, 161102 (2010).[29] A.W. Steiner and A. L. Watts, Phys. Rev. Lett. 103,

181101 (2009).[30] D. H. Wen, B. A. Li, and P. G. Krastev, Phys. Rev. C 80,

025801 (2009).[31] I. Vidana, C. Providencia, A. Polls, and A. Rios, Phys.

Rev. C 80, 045806 (2009).[32] T. Sil et al., Phys. Rev. C 71, 045502 (2005).

v090M

Sk7H

FB-8

SkP

HFB

-17SkM

*

Ska

Sk-Rs

Sk-T4

DD

-ME2

DD

-ME1

FSUG

oldD

D-PC

1PK

1.s24N

L3.s25

G2

NL-SV2PK

1N

L3N

L3*

NL2

NL1

0 50 100 150 L (MeV)

0.1

0.15

0.2

0.25

0.3

!rnp

(fm

)

Linear Fit, r = 0.979Nonrelativistic modelsRelativistic models

D1S

D1N

SGII

Sk-T6SkX SLy5

SLy4

MSkA

MSL0

SIVSkSM

*SkM

P

SkI2SV

G1

TM1

NL-SH

NL-R

A1

PC-F1

BC

P

RH

F-PKO

3Sk-G

s

RH

F-PKA

1PC

-PK1

SkI5

FIG. 3 (color online). Neutron skin of 208Pb against slopeof the symmetry energy. The linear fit is !rnp " 0:101#0:001 47L. A sample test constraint from a 3% accuracy inAPV is drawn.

PRL 106, 252501 (2011) P HY S I CA L R EV I EW LE T T E R Sweek ending24 JUNE 2011

252501-4

X. Roca-Maza, at al. Phys. Rev. Lett. 106, 252501 (2011)

Method1 2 3 4 5 6

S (fm

)

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

Pb Neutron Skin Radius208

PREX

Pb(p,p)208

Antiprotonic Atoms

EDPPDR

Pionic Atoms


! Suggest what PV experiment can’t do:good quality skin thickness measurements of a wide range of nuclei:

Do we need this systematics?

Neutron skin Radii: Where are we?

ity of S of a heavy nucleus with L in nuclear models[2,4,7]. The correction with Ksym does not alter the situ-ation as !! 1=9 is small. One can use Eq. (5) in other massregions by calculating ! from "A of Eq. (4). We havechecked numerically in multiple forces that the resultsclosely agree with Eq. (3) for the 40 " A " 238 stablenuclei given in Fig. 2.With the help of Eq. (5) for t (using "A to compute !), wenext analyze constraints on the density dependence of thesymmetry energy by optimization of (2) to experimental Sdata. We employ csym#"$ % 31:6#"="0$# MeV [6–9] andtake as experimental baseline the neutron skins measuredin 26 antiprotonic atoms [20] (see Fig. 2). These dataconstitute the largest set of uniformly measured neutronskins over the mass table till date. With allowance for theerror bars, they are fitted linearly by S % #0:9& 0:15$I '#(0:03& 0:02$ fm [20]. This systematics renders com-parisons of skin data with DM formulas, which by con-struction average the microscopic shell effect, moremeaningful [26]. We first set bn % bp (i.e., Ssw % 0) asdone in the DM [12,23,26] and in the analysis of data inRef. [19]. Following the above, we find L % 75& 25 MeV(# % 0:79& 0:25). The range !L % 25 MeV stems fromthe window of the linear averages of experiment. The Lvalue and its uncertainty obtained from neutron skins withSsw % 0 is thus quite compatible with the quoted con-straints from isospin diffusion and isoscaling observablesin HIC [6–8]. On the other hand, the symmetry term of theincompressibility of the nuclear EOS around equilibrium(K % Kv ' K$%2) can be estimated using information ofthe symmetry energy as K$ ) Ksym ( 6L [5–7]. The con-straint K$ % (500& 50 MeV is found from isospin dif-fusion [6,7], whereas our study of neutron skins leads toK$ % (500'125

(100 MeV. A value K$ % (550& 100 MeVseems to be favored by the giant monopole resonance(GMR) measured in Sn isotopes as is described in [13].Even if the present analyses may not be called definitive,

significant consistency arises among the values extractedfor L and K$ from seemingly unrelated sets of data fromreactions, ground-states of nuclei, and collectiveexcitations.To assess the influence of the correction Ssw in (2), wecompute the surface widths bn and bp in ASINM [22]. Thisyields the bn#p$ values of a finite nucleus if we relate theasymmetry %0 in the bulk of ASINM to I by %0#1' xA$ %I' xAIC [21–23]. In doing so, we find that Eq. (2) repro-duces trustingly S (and its change with I) of self-consistentThomas-Fermi calculations of finite nuclei made with thesame nuclear force. Also, Ssw is very well fitted by Ssw %&swI. All slopes &sw of the forces of Fig. 1(c) lie between&min

sw % 0:15 fm (SGII) and &maxsw % 0:31 fm (NL3). Wethen reanalyze the experimental neutron skins includingSmin

sw and Smaxsw in Eq. (2) to simulate the two conceivableextremes of Ssw according to mean field models. Theresults are shown in Fig. 3. Our above estimates of L andK$ could be shifted by up to(25 and'125 MeV, respec-tively, by nonzero Ssw. This is on the soft side of the HIC[6–8] and GMR [13] analyses of the symmetry energy, butcloser to the alluded predictions from nucleon emissionratios [9], the GDR [14], and nuclear binding systematics[17]. One should mention that the properties of csym#"$derived from terrestrial nuclei have intimate connections toastrophysics [3,4,10]. As an example, we can estimate thetransition density "t between the crust and the core of aneutron star [3,10] as "t="0 ! 2=3' #2=3$#Ksym=2Kv,

following the model of Sect. 5.1 of Ref. [10]. The con-straints from neutron skins hereby yield "t ! 0:095&0:01 fm(3. This value would not support the directURCA process of cooling of a neutron star that requiresa higher "t [3,10]. The result is in accord with "t !0:096 fm(3 of the microscopic EOS of Friedman andPandharipande [27], as well as with "t ! 0:09 fm(3 pre-

00.1

0.2I = (N!") / #

-0.1

0

0.1

0.2

0.3

S (f

m)

4020Ca 58

28Ni

5426Fe

6028Ni

5626Fe 59

27Co

5726Fe

10648Cd

11250Sn

9040Zr

6428Ni

11650Sn

12252Te

12452Te

4820Ca

9640Zr

12050Sn

11648Cd

12652Te128

52Te

12450Sn130

52Te

20983Bi

20882Pb

23290Th

23892U

experimentlinear averageof experimentprediction Eq. (2)FSUGoldSLy4

FIG. 2 (color online). Comparison of the fit described in thetext of Eq. (2) with the experimental neutron skins from anti-protonic measurements and their linear average S %#0:9& 0:15$I ' #(0:03& 0:02$ fm [20]. Results of the modernSkyrme SLy4 and relativistic FSUGold forces are also shown.

20 60 100 140L (MeV)

-700

-600

-500

-400

-300

K$ (

MeV

)

isospin diffusion

GMRof Sn

isospindiffusion

Ssw= 0

Sswmin

Sswmax

FIG. 3 (color online). Constraints on L and K$ from neutronskins and their dependence on the Ssw correction of Eq. (2). Thecrosses express the L and K$ ranges compatible with the un-certainties in the skin data. The shaded regions depict theconstraints on L and K$ from isospin diffusion [6,7] and onK$ as determined in [13] from the GMR of Sn isotopes.

PRL 102, 122502 (2009) P HY S I CA L R EV I EW LE T T E R S week ending27 MARCH 2009

122502-3

M. Centelles, et al Phys. Rev. Lett. 102, 122502 (2009)

A. Trzcinska et al., Phys. Rev. Lett. 87, 082501 (2001);J. Jastrzebski et al., Int. J. Mod. Phys. E 13, 343 (2004).

NSkin from antiprotonic-atoms: correlation between thickness and isospin

Neutron radius is not directly measured ! strong dependence on theoretical models.


If YES then ... shine light on the nucleus!

!"#$%$&'!"#$%$&'!"#$%$&'!"#$%$&' !!!!(((( )#"'")%"*+!',"&)#"'")%"*+!',"&)#"'")%"*+!',"&)#"'")%"*+!',"& -./0-./0-./0-./0

12.3#,$4.5 1678.0(9: ;;;;<<<<;;;;

!!!!! "#$%&'(% )*+, (-&./ "#$0.0*/*+1 $2"#$+$23 .2%42(&+#$23

5.++(#46$#746.'+$# ! #8783847.++(#4#.%*&3

5$3+43*7"/(49:;<4.""#$=*7.+*$2>

!!!!!

<?4-


208Pb neutron skin from Coherent π0

D. Watts, et al,EPJ Web of Conferences 37, 01027 (2012) Method

1 2 3 4 5 6 7S

(fm)

0.1

0.2

0.3

0.4

0.5

Pb Neutron Skin Radius208

PREX

Pb(p,p)208

Antiprotonic Atoms

EDPPDR

Pionic Atoms

Coh.Ph.!

208Pb neutron skin from Coherent !!!!0

E""""=165±5 MeV E""""=190±5 MeV

Skin ~ 0.12 ±0.02(stat) fm

Systematic error currently being finalised. expect < ~0.05 fm

d## ##

/dq

µµ µµb

.fm

p,d pickupPREX@JLAB

Proton ScattAntiproton@CERN

Dipole

MAMI-Cq = 0 to 2q =1st minimaq=2nd minimaq =3rd minima

E"" ""=

155

±5

E"" ""=

165

±5

E"" ""=

175

±5

E"" ""=

185

±5

E"" ""=

195

±5

|q| = p""""-p!!!!0 (fm-1)

d## ##

/dq

µµ µµb

.fm

|q| = p""""-p!!!!0 (fm-1)

Ne

utr

on

sk

in t

hic

kn

es

s (

fm)

! (",!",!",!",!) + !!!!0-A complex optical potential (Drecschel et al NPA 660 (1999))Including detector resolution +interpolated fit for neutron skin + incoherent background

! Incoherent background alone

PhD: Tarbert(Edinburgh)

208Pb neutron skin from Coherent !!!!0

E""""=165±5 MeV E""""=190±5 MeV

Skin ~ 0.12 ±0.02(stat) fm

Systematic error currently being finalised. expect < ~0.05 fm

d## ##

/dq

µµ µµb

.fm

p,d pickupPREX@JLAB

Proton ScattAntiproton@CERN

Dipole

MAMI-Cq = 0 to 2q =1st minimaq=2nd minimaq =3rd minima

E"" ""=

155

±5

E"" ""=

165

±5

E"" ""=

175

±5

E"" ""=

185

±5

E"" ""=

195

±5

|q| = p""""-p!!!!0 (fm-1)

d## ##

/dq

µµ µµb

.fm

|q| = p""""-p!!!!0 (fm-1)

Ne

utr

on

sk

in t

hic

kn

es

s (

fm)

! (",!",!",!",!) + !!!!0-A complex optical potential (Drecschel et al NPA 660 (1999))Including detector resolution +interpolated fit for neutron skin + incoherent background

! Incoherent background alone

PhD: Tarbert(Edinburgh)

New experimental campaign@A2 (October 2012)

116,120,124Sn, 58Ni, 208Pb (I = 0.03÷0.21)

208Pb Target



...perspective are excellent!Near future (2013-2015) ....

Radius Puzzle: ISR and d-FF Neutron form factor: new neutron detectorNucleon polarizabilities with real photonsHigh resolution pion spectroscopy of light hypernuclei

PRECISION

COMPLEXITY

The Low Energy Frontier @ Mainz: Results and ...



Hadron Spectroscopy


Astrophysics


...thediscovery

(HE, Precision, Astroparticle)

frontier

!"#$%%&'()(*%


Conventional strategies for DM searches

Harald Merkel, 50th Int. Winter Meeting on Nuclear Physics, Bormio 2012

Conventional strategies for dark matter search in particle physics

Direct Production:

Tevatron, LHC

Direct Search:

CDMS, DAMA/LIBRA,XENON, CRESST, LUX,COUPP, KIMS, ...

Indirect Search:

PAMELA, Fermi, HESS,ATIC, WMAP, ...

A bottom up approach: Looking for interacting particles


Conventional strategies for DM searches

Assumptions:There is dark matter (SUSY or something else) Dark matter interacts with Standard Model matter (besides gravity) Dark matter interacts via a “dark force”

Question:What is the character of this “dark force”? Scalar, pseudo-scalar, vector bosons? Massive or mass-less? Mass range? Size of the coupling constant?


Conventional strategies for dark matter search in particle physics

Direct Production:

Tevatron, LHC

Direct Search:

CDMS, DAMA/LIBRA,XENON, CRESST, LUX,COUPP, KIMS, ...

Indirect Search:

PAMELA, Fermi, HESS,ATIC, WMAP, ...

A bottom up approach: Looking for interacting particles


A top down motivation

● Extra U(1) gauge bosons ubiquitous in well motivated extension of SM● U(1) gauge bosons may be hidden (no interaction with SM)● No reason for U(1) boson to be heavy● Dark matter couples to U(1) bosons γ and γ’

● Mixing parameter ε of γ/γ’ mixing● Boson mass mγ’ > 0 ⇒ decay suppressed, macroscopic lifetime

⇒ Look for χ at high energies OR for γ’ at low energies!B. Holdom Phys. Lett. B 166 (1986) 196


Kinetic mixing

Dark matter couples to U(1) bosons γ and γ �:

e

e

! "!#

$

$_

L ⊃ − 14

FSMµν Fµν

SM − 14

Fhiddenµν Fµν

hidden +ε2

FSMµν Fµν

hidden + m2γ �Ahidden

µ Aµhidden

Renormalization of charge:

⇒ Mixing standard-model charge — “dark” charge

Mixing parameter ε of γ �/γ mixing

Boson mass mγ � > 0 ⇒ decay suppressed, macroscopic lifetime

⇒ Look for χ at high energies OR for γ � at low energies!B. Holdom, Phys. Lett. B 166 (1986) 196


Dark PhotonLight weakly coupled U(1) gauge bosonN. Arkani-Hamed, et al., Phys. Rev. D 79 (2009) 015014

Proton Radius PuzzleD. Tucker-Smith and I. Yavin Phys. Rev. D83 (2011) 101702

(g-2)µ anomalyM. Pospelov, Phys. Rev. D80 (2009) 095002

...it explains ...terrestrial anomalies (DAMA, CDMS, XENON)satellite anomalies(PAMELA, FERMI)

Probing Dark Forces @ GeV Scale


Probing Dark Forces @ GeV Scale

Prediction are testable:Large cross section in leptons

' World wide effort (CERN, DESY, JLAB, MAMI, all e+e- colliders, ...)Proton Radius Puzzle

D. Tucker-Smith and I. Yavin Phys. Rev. D83 (2011) 101702

(g-2)µ anomalyM. Pospelov, Phys. Rev. D80 (2009) 095002

...it explains ...terrestrial anomalies (DAMA, CDMS, XENON)satellite anomalies(PAMELA, FERMI)

Dark PhotonLight weakly coupled U(1) gauge bosonN. Arkani-Hamed, et al., Phys. Rev. D 79 (2009) 015014


Search for the Dark Photon @ MAMI

Bump Hunt: Quasi-photoproduction off 181Ta target

H. Merkel et al., Phys. Rev. Lett. 106 (2011) 251802

Beam current:! 100µALuminosity: L = 1.7·1035 (s·cm2)-1

Minimal angles for spectrometers Geometry as symmetric as possible

(background reduction)

Coincidence time resolution! ≈ 1 ns FWHMAlmost no accidental background! ≈ 5%Above background: only coincident e+e− pairs!

δme+e− <0.5MeV/c2


Mixin

g Par

amete

r 2

Dark Photon Mass m ’ (MeV/c2)

10-7

10-6

10-5

10-4

10 100

(g-2)!(g-2)e vs. BaBar

A1-2

011

e"e #!"!

|(g-2)!|< 2

E774

KLOE

APEX

Bump Hunt: Quasi-photoproduction off 181Ta target

% Fight background ....... with high intensity ... ... and resolution.

Search for the Dark Photon @ MAMI H. Merkel et al., Phys. Rev. Lett. 106 (2011) 251802

Feasibility:Background (within 1%) First exclusion limits 10−3

New ε/mγ’ scan 4 days beam time!!

APEX: S. Abrahamyan et al., Phys. Rev. Lett. 107 (2011) 191804 KLOE: F. Archilli et al., Phys. Lett. B. 706 (2012) 251

PRELIMINARY

Future: Low mass region <50 MeV/c2 and small dark photon coupling ε2


... MESA beyond MAMI ...

Harald Merkel, European Few Body 22, Krakow 09/2013

MESA: Mainz Energy recovering Superconducting Accelerator

Superconducting LINAC

Three recirculation arcs for external beam

high external current for “next generation” parity violation experiments

Energy recovery mode (half wave-length recirculation) for internal target experiments

Current Energy Luminosity

External Beam Mode: 150 µA 200 MeV 1039cm

−2s−1

Energy Recovery Mode: 10 mA 150 MeV 1036cm

−2s−1

Mainz Energy recovering Superconducting Accelerator



...perspective are excellent!Near future (2013-2015) ....

Radius Puzzle: ISR and d-FF Neutron form factor: new neutron detectorNucleon polarizabilities with real photonsHigh resolution pion spectroscopy of light hypernuclei

PRECISION

COMPLEXITY DISCOVERY

POTENTIAL

The Low Energy Frontier @ Mainz: Results and ...


the low energy physics frontier of the standard model at the mami accelerator

Science

nuclear recoil

rutherford scattering

magnetic moments

form factors

mami legacy

low energy physics frontier

virtual compton scattering

magnetic polarizabilities