DOCSLIB.ORG

The Proton Radius Puzzle- Why We All Should Care Gerald A

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Proton Radius Puzzle- Why We All Should Care Gerald A The Proton Radius Puzzle- Why we all should care Gerald A. Miller, University of Washington Feb. 2014 Pohl et al Nature 466, 213 (8 July 2010) 4 % Difference muon H rp =0.84184 (67) fm Small 2 2 dGE(Q ) rp 6 ⌘ dQ2 electron H rp =0.8768 (69)fm Large Q2=0 Pohl, Gilman, Miller, Pachucki electron-p scattering rp =0.875 (10)fm (ARNPS63, 2013) PRad at JLab- lower Q2 C Carlson PPNP 4 2 2 2 3 10 Q 5 10− GeV 82,59(2015) ⇥ ⇥ 3 2 2 − <latexit sha1_base64="2ttW2dt5BFvgQ5BSt5m7fAu5dr4=">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</latexit> 7.7 10− Q 0.13 fm ⇥ 1 The Proton Radius Puzzle- Why we all should care Gerald A. Miller, University of Washington Feb. 2014 Pohl et al Nature 466, 213 (8 July 2010) 4 % Difference muon H rp =0.84184 (67) fm Small 2 2 dGE(Q ) rp 6 ⌘ dQ2 electron H rp =0.8768 (69)fm Large Q2=0 Pohl, Gilman, Miller, Pachucki electron-p scattering rp =0.875 (10)fm (ARNPS63, 2013) PRad at JLab- lower Q2 C Carlson PPNP 4 2 2 2 3 10 Q 5 10− GeV 82,59(2015) ⇥ ⇥ 3 2 2 − <latexit sha1_base64="2ttW2dt5BFvgQ5BSt5m7fAu5dr4=">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</latexit> 7.7 10− Q 0.13 fm ⇥ 1 4 % in radius: why care? • Can’t be calculated to that accuracy? Is the muon-proton interaction the same as the electron-proton interaction? Something violation of universality happening connections with muon g-2? here ??? connections with LHCb ? Kaons ? Kohl talk Outline - a) review history experiments b) List & explain possible resolutions 2 university of melbourne cssm, university of adelaide TheMuonic Experiment hydrogen experiment and rp Muonic Hydrogen 2P1/2 The Lamb shift is the splitting of the degenerate 2S1/2 and 2P1/2 eigenstates The Lamb shift is the splitting ∆ 2S−2P ELamb of the degenerate 2S1/2 and 2P1/2 eigenstates,Dominant due to in vacuum μH polar- vacuum polarization 205 of 206 meV ization 2S1/2 Dominant in eH electron self-energy ∞ 2 Zα α d(q ) −meqr 4 2 VVP(r)=− 2 e 1 − 2 1+ 2 2 r 3π 4 q q q Proton radius in! " # $ = rp ? Lamb shift J. Carroll — Proton Radius Puzzle — Slide 8 pt 2 2 ∆E = V V = ⇡↵ (0) ( 6G0 (0)) h S| C − C | Si 3 | S | − E • Muon/electron mass ratio 205! 8 million times larger for muon 3 1 RESEARCH ARTICLES Figure 3 shows the two measured mp res- The uncertainties result from quadratically This rE value is compatible with our pre- onances. Details of the data analysis are given adding the statistical and systematic uncertain- vious mp result (6), but 1.7 times more precise, in (12). The laser frequency was changed every ties of ns and nt. and is now independent of the theoretical pre- few hours, and we accumulated data for up to The charge radius. The theory (14, 16–22) diction of the 2S-HFS. Although an order of 13 hours per laser frequency. The laser frequen- relating the Lamb shift to rE yields (13): magnitude more precise, the mp-derived proton cy was calibrated [supplement in (6)] by using radius is at 7s variance with the CODATA-2010 th 2 well-known water absorption lines. The reso- DE 206:0336(15 − 5:2275(10 r DETPE (7)valueofr =0.8775(51)fmbasedonHspec- L ¼ Þ Þ E þ E nance positions corrected for laser intensity ef- 7 troscopy and electron-proton scattering. fects using the line shape model (12)are ð Þ Magnetic and Zemach radii. The theoretical stat sys where E is in meV and rE is the root mean prediction (17, 18, 27–29)ofthe2S-HFSis(13) ns 54611:16(1:00) (30) GHz 2 ¼ ð Þ square (RMS) charge radius given in fm and 2 3 2 th pol stat sys defined as rE = ∫d rr rE(r) with rE being the DE 22:9763(15 − 0:1621(10)rZ DE nt 49881:35(57) (30) GHz 3 HFS ¼ Þ þ HFS ¼ ð Þ normalized proton charge distribution. The first 9 where “stat” and “sys” indicate statistical and sys- term on the right side of Eq. 7 accounts for ð Þ tematic uncertainties, giving total experimental un- radiative, relativistic, and recoil effects. Fine and where E is in meV and rZ is in fm. The first term is certainties of 1.05 and 0.65 GHz, respectively. hyperfine corrections are absent here as a con- the Fermi energy arising from the interaction Although extracted from the same data, the fre- sequence of Eqs. 4. The other terms arise from between the muon and the proton magnetic mo- quency value of the triplet resonance, nt,isslightly the proton structure. The leading finite size effect ments, corrected for radiative and recoil con- 2 more accurate than in (6)owingtoseveralimprove- −5.2275(10)rE meV is approximately given by tributions, and includes a small dependence of 2 ments in the data analysis. The fitted line widths Eq. 1 with corrections given in (13, 17, 18). −0.0022rE meV = −0.0016 meV on the charge are 20.0(3.6) and 15.9(2.4) GHz, respectively, com- Two-photon exchange (TPE) effects, including the radius (13). patible with the expected 19.0 GHz resulting from proton polarizability, are covered by the term The leading proton structure term depends the laser bandwidth (1.75 GHz at full width at half DETPE =0.0332(20)meV(19, 24–26). Issues on rZ,definedas maximum) and the Doppler broadening (1 GHz) related with TPE are discussed in (12, 13). th exp of the 18.6-GHz natural line width. The comparison of DEL (Eq. 7) with DEL 3 3 ′ ′ ′ rZ d r d r r r (r)r (r − r ) 10 The systematic uncertainty of each measure- (Eq. 5) yields ¼ ∫ ∫ E M ð Þ ment is 300 MHz, given by the frequency cal- exp th ibration uncertainty arising from pulse-to-pulse rE 0:84087(26) (29) fm with rM being the normalized proton mag- fluctuations in the laser and from broadening ¼ 0:84087(39) fm 8 netic moment distribution. The HFS polariz- effects occurring in the Raman process. Other ¼ ð Þ systematic corrections we have considered are Muonic Hydrogen Experiment the Zeeman shift in the 5-T field (<60 MHz), AC and DC Stark shifts (<1 MHz), Doppler Randolf shift (<1 MHz), pressure shift (<2 MHz), and black-body radiation shift (<<1 MHz). All these Pohl typically important atomic spectroscopy system- atics are small because of the small size of mp. The Lamb shift and the hyperfine splitting. From these two transition measurements, we can independently deduce both the Lamb shift (DEL = DE2P1/2−2S1/2) and the 2S-HFS splitting (DEHFS) by the linear combinations (13) 1 3 hns hnt DEL 8:8123 2 meV 4 þ 4 ¼ þ ð Þ hns − hnt DEHFS − 3:2480 2 meV 4 ¼ ð Þ ð Þ Finite size effects are included in DEL and Aldo DEHFS. The numerical terms include the cal- culated values of the 2P fine structure, the 2P3/2 hyperfine splitting, and the mixing of the 2P Antognini states (14–18). The finite proton size effects on the 2P fine and hyperfine structure are smaller than 1 × 10−4 meV because of the small overlap between the 2P wave functions and the nu- cleus. Thus, their uncertainties arising from the proton structure are negligible. By using From 2013 the measured transition frequencies ns and nt in Eqs. 4, we obtain (1 meV corresponds to 241.79893 GHz) Science paper Fig. 1. (A)Formationofmpinhighlyexcitedstatesandsubsequentcascadewithemissionof“prompt” DEexp 202:3706(23) meV 5 L ¼ ð Þ Ka, b, g.(B)Laserexcitationofthe2S-2Ptransitionwith subsequent decay to the ground state with Ka emission. (C)2Sand2Penergylevels.Themeasuredtransitionsns and nt are indicated together with DEexp 22:8089(51) meV 6 4 HFS ¼ ð Þ the Lamb shift, 2S-HFS, and 2P-fine and hyperfine splitting. EMBARGOED UNTIL 2PM U.S. EASTERN TIME ON THE THURSDAY BEFORE THIS DATE: 418 25 JANUARY 2013 VOL 339 SCIENCE www.sciencemag.org The proton radius puzzle In a picture The proton rms charge radius measured with electrons: 0.8770 ± 0.0045 fm muons: 0.8409 ± 0.0004 fm 7.9 σ Large µp 2013 electron avg. Small scatt. JLab µp 2010 scatt. Mainz 2.5 % 0.01% H spectroscopy 0.83 0.84 0.85 0.86 0.87 0.88 0.89 0.9 R. Pohl
Load more

Recommended publications
  • The MUSE Experiment and the Proton Radius
    Introduction Resolutions to the Puzzle MUSE - MUon Scattering Experiment The MUSE experiment and the Proton Radius Cristina Collicott SPIN 2016 Cristina Collicott SPIN 2016 1/17 Introduction Resolutions to the Puzzle MUSE - MUon Scattering Experiment The Proton Radius Puzzle How big is the proton? Easy question to ask, not so easy to answer! Currently an unanswered problem in physics Cristina Collicott SPIN 2016 2/17 Introduction Resolutions to the Puzzle MUSE - MUon Scattering Experiment The Proton Radius Puzzle What is the proton radius puzzle? The proton charge radius, measured via muonic hydrogen spectroscopy, is 4% smaller than results from hydrogen spectroscopy and elastic electron proton scattering experiments. Cristina Collicott SPIN 2016 3/17 Introduction Resolutions to the Puzzle MUSE - MUon Scattering Experiment The Proton Radius Puzzle - scattering Rosenbluth scattering: 2 2 2 2 dσ dσ GE (Q )+ xGM (Q ) 2 2 2 θ = + 2xGM (Q ) tan dΩ dΩ (point.) 1 + x 2 Sach's form factors (F1,F2 Dirac and Pauli FFs) 2 2 2 GE (Q ) = F1(Q ) − xF2(Q ) 2 2 2 GE (Q ) = F1(Q ) − xF2(Q ) hq 2 x = 2Mc Cristina Collicott SPIN 2016 4/17 Introduction Resolutions to the Puzzle MUSE - MUon Scattering Experiment The Proton Radius Puzzle - scattering Rosenbluth scattering: 2 2 2 2 dσ dσ GE (Q )+ xGM (Q ) 2 2 2 θ = + 2xGM (Q ) tan dΩ dΩ (point.) 1 + x 2 Derivative in the Q2 ! 0 limit 2 2 dGE (Q ) < rE >= −6 2 dQ Q2!0 We expect identical results for hq 2 experiments with ep and µp x = 2Mc scattering..
    [Show full text]
  • Arxiv:2103.17101V1 [Physics.Hist-Ph] 29 Mar 2021 1/2 1/2 Are Equal, While That of 2P3/2 Is Higher by About 40 Μev; This Is the fine Structure (FS), Fig
    April 1, 2021 0:46 WSPC Proceedings - 9in x 6in protonr page 1 1 THE QUEST FOR THE PROTON CHARGE RADIUS ISTVAN´ ANGELI Institute of Experimental Physics, University of Debrecen, Hungary A slight anomaly in optical spectra of the hydrogen atom led Willis E. Lamb to the search for the proton size. As a result, he found the shift of the 2S1/2 level, the first experimental demonstration of quantum electrodynamics (QED). In return, a modern test of QED yielded a new value of the charge radius of the proton. This sounds like Baron M¨unchausen's tale: to pull oneself out from the marsh by seizing his own hair. An independent method was necessary. Muonic hydrogen spectroscopy came to the aid. However, the high-precision result significantly differed from the previous { electronic { values: this is (was?) the proton radius puzzle (2010-2020?). This puzzle produced a decade-long activity both in experimental work and in theory. Even if the puzzle seems to be solved, the precise determination of the proton charge radius requires further efforts in the future. 1. The Dirac equation; anomalies in hydrogen spectra (1928{1938) In 1928, P.A.M. Dirac published his relativistic wave equation implying two important consequences: (1) The electron has an intrinsic magnetic dipole moment µe = 1 × µB (µB: Bohr magneton) in agreement with the experiment (1925: George Uhlenbeck, Samuel Goudsmit). (2) If in the hydrogen atom the electron moves in the field of a Coulomb potential V (r) ∼ 1=r, then its energy E(n; j) is determined by the principal quantum number n and the total angular momentum quan- tum number j, but not by the orbital angular momentum l and spin s, separately.
    [Show full text]
  • The Proton Radius Puzzle Μ
    The proton radius puzzle µ A. Antognini Paul Scherrer Institute ETH, Zurich Switzerland CREMA collaboration Laser spectroscopy of muonic atoms µ 2P 2S-2P Laser excitation Energy 2S 1S μ • 2S-2P p From 2S-2P • 2S-2P μd ꔄ charge radii • 2S-2P μ3He, μ4He Aldo Antognini Rencontres de Moriond 19.03.2017 2 Three ways to the proton radius p p e- H 2 e- µ- e--p scattering H spectroscopy µp spectroscopy 6.7 σ CODATA-2010 µp 2013 scatt. JLab µp 2010 scatt. Mainz H spectroscopy 0.82 0.83 0.84 0.85 0.86 0.87 0.88 0.89 0.9 Proton charge radius [fm] Pohl et al., Nature 466, 213 (2010) Antognini et al., Science 339, 417 (2013) Pohl et al., Science 353, 669 (2016) Aldo Antognini Rencontres de Moriond 19.03.2017 3 Extracting the proton radius from 훍p Measure 2S-2P splitting (20 ppm) 8.4 meV 2P F=2 and compare with theory 3/2 F=1 2P1/2 F=1 → proton radius F=0 ∆Eth . − . r2 . 2P −2S = 206 0336(15) 5 2275(10) p +00332(20) [meV] 206 meV 50 THz 6 µm fin. size: 3.8 meV F=1 2π(Zα) 2 2 2S ∆Esize = r |Ψnl(0)| 1/2 m ≈ 200m 3 p 23 meV µ e 4 2(Zα) 3 2 F=0 3 m r δl = 3n r p 0 Aldo Antognini Rencontres de Moriond 19.03.2017 4 Principle of the µp 2S-2P experiment Produce many µ− at keV energy − Form µp by stopping µ in 1 mbar H2 gas Fire laser to induce the 2S-2P transition Measure the 2 keV X-rays from 2P-1S decay µp formation Laser excitation Plot number of X-rays vs laser frequency ] n~14 2 P -4 7 Laser 6 1 % 99 % 2 S 5 2 P 4 2 S 3 2 keV 2 keV γ γ 2 delayed / prompt events [10 1 0 1 S 49.75 49.8 49.85 49.9 49.95 1 S laser frequency [THz] Aldo Antognini Rencontres de Moriond 19.03.2017 5 The setup at the Paul Scherrer Institute Aldo Antognini Rencontres de Moriond 19.03.2017 6 The first 훍p resonance (2010) Discrepancy: 5.0 σ ↔ 75 GHz ↔ δν/ν =1.5 × 10−3 ] -4 7 CODATA-06 our value 6 e-p scattering H2O 5 calib.
    [Show full text]
  • The Proton Radius Puzzle-Why We All Should Care
    SNSN-323-63 September 27, 2018 The Proton Radius Puzzle- Why We All Should Care Gerald A. Miller1 Physics Department, University of Washington, Seattle, Washington 98195-1560, USA The status of the proton radius puzzle (as of the date of the Confer- ence) is reviewed. The most likely potential theoretical and experimental explanations are discussed. Either the electronic hydrogen experiments were not sufficiently accurate to measure the proton radius, the two- photon exchange effect was not properly accounted for, or there is some kind of new physics. I expect that upcoming experiments will resolve this issue within the next year or so. PRESENTED AT Conference on the Intersections between particle and nuclear physics, arXiv:1809.09635v1 [physics.atom-ph] 25 Sep 2018 Indian Wells, USA, May 29{ June 3, 2018 1This work was supported by the U. S. Department of Energy Office of Science, Office of Nuclear Physics under Award Number DE-FG02-97ER-41014,. This title is chosen because understanding of the proton radius puzzle requires knowledge of atomic, nuclear and particle physics. The puzzle began with the pub- lication of the results of the 2010 muon-hydrogen experiment in 2010 [1] and its confirmation [2]. The proton radius (r2 = 1=6G0 (Q2 = 0) was measured to be p − E rp = 0:84184(67) fm, which contrasted with the value obtained from electron spec- troscopy rp = 0:8768(69) fm. This difference of about 4% has become known as the proton radius puzzle [3]. We use the technical terms: the radius 0.87 fm is denoted as large, and the one of 0.84 fm as small.
    [Show full text]
  • The Proton Radius Puzzle and the Electro-Strong Interaction
    The Proton Radius Puzzle and the Electro-Strong Interaction The resolution of the Proton Radius Puzzle is the diffraction pattern, giving another wavelength in case of muonic hydrogen oscillation for the proton than it is in case of normal hydrogen because of the different mass rate. Taking into account the Planck Distribution Law of the electromagnetic oscillators, we can explain the electron/proton mass rate and the Weak and Strong Interactions. Lattice QCD gives the same results as the diffraction patterns of the electromagnetic oscillators, explaining the color confinement and the asymptotic freedom of the Strong Interactions. Contents Preface ................................................................................................................................... 2 The Proton Radius Puzzle ......................................................................................................... 2 Asymmetry in the interference occurrences of oscillators ............................................................ 2 Spontaneously broken symmetry in the Planck distribution law .................................................... 4 The structure of the proton ...................................................................................................... 6 The weak interaction ............................................................................................................... 6 The Strong Interaction - QCD .................................................................................................... 7 Confinement
    [Show full text]
  • Arxiv:1909.08108V3 [Hep-Ph] 26 Sep 2019 Value Obtained from Muonic Hydrogen Is Re = 0.84087(39) Fm [8], While the Most Recent CODATA P Value Is Re = 0.8751(61) Fm [9]
    The Proton Radius Puzzle Gil Paz Department of Physics and Astronomy, Wayne State University, Detroit, Michigan 48201, USA Abstract: In 2010 the proton charge radius was extracted for the first time from muonic hydrogen, a bound state of a muon and a proton. The value obtained was five standard deviations away from the regular hydrogen extraction. Taken at face value, this might be an indication of a new force in nature coupling to muons, but not to electrons. It also forces us to reexamine our understanding of the structure of the proton. Here I describe an ongoing theoretical research effort that seeks to address this \proton radius puzzle". In particular, I will present the development of new effective field theoretical tools that seek to directly connect muonic hydrogen and muon-proton scattering. Talk presented at the 2019 Meeting of the Division of Particles and Fields of the American Physical Society (DPF2019), July 29{August 2, 2019, Northeastern University, Boston, C1907293. 1 Introduction How big is the proton? To answer such a question one needs to define how the proton size is measured. For example, one can use an electromagnetic probe to determine the proton's size. A \one photon" electromagnetic interaction with an on-shell proton can be described by two form 2 factors: F1 and F2. These form factors are functions of q , the square of the four-momentum transfer. Two different linear combinations of F1 and F2 define the \electric" form factor: GE = 2 2 F1 + q F2=4M , where M is the proton mass, and the \magnetic" form factor: GM = F1 + F2.
    [Show full text]
  • Studying the Proton “Radius” Puzzle with Μp Elastic Scattering
    AProposalforthePaulScherrerInstituteπM1 beam line Studying the Proton “Radius” Puzzle with µp Elastic Scattering J. Arrington,1 F. Benmokhtar,2 E. Brash,2 K. Deiters,3 C. Djalali,4 L. El Fassi,5 E. Fuchey,6 S. Gilad,7 R. Gilman (Contact person),5 R. Gothe,4 D. Higinbotham,8 Y. Ilieva,4 M. Kohl,9 G. Kumbartzki,5 J. Lichtenstadt,10 N. Liyanage,11 M. Meziane,12 Z.-E. Meziani,6 K. Myers,5 C. Perdrisat,13 E. Piasetzsky (Spokesperson),10 V. Punjabi,14 R. Ransome,5 D. Reggiani,3 A. Richter,15 G. Ron,16 A. Sarty,17 E. Schulte,6 S. Strauch,4 V. Sulkosky,7 A.S. Tadapelli,5 and L. Weinstein18 1Argonne National Lab, Argonne, IL, USA 2Christopher Newport University, Newport News, Virginia, USA 3Paul Scherrer Institut, CH-5232 Villigen, Switzerland 4University of South Carolina, Columbia, South Carolina, USA 5Rutgers University, New Brunswick, New Jersey, USA 6Temple University, Philadelphia, Pennsylvania, USA 7Massachusetts Institute of Technology, Cambridge, Massachusetts, USA 8Jefferson Lab, Newport News, Viginia, USA 9Hampton University, Hampton, Virginia, USA 10Tel Aviv University, Tel Aviv, Israel 11University of Virginia, Charlottesville, Virginia, USA 12Duke University, Durham, North Carolina, USA 13College of William & Mary, Williamsburg, Virginia, USA 14Norfolk State University, Norfolk, Virginia, USA 15Technical University of Darmstadt, Darmstadt, Germany 16Hebrew University of Jerusalem, Jerusalem, Israel 17St. Mary’s University, Halifax, Nova Scotia, Canada 18Old Dominion University, Norfolk, Virginia, USA About 1.5 years after the radius of muonic hydrogen was found to be 5σ inconsistent with earlier determinations from atomic hydrogen level transitions and ep elastic scattering, no resolution to the puzzle has been found.
    [Show full text]
  • PDF) and Fragmentation Function (FF)
    Lattice QCD Method To Study Proton Radius Puzzle Gouranga C Nayak, ∗ (Dated: August 6, 2019) Abstract Recently there has been disagreement between various experiments about the value of the proton radius which is known as the proton radius puzzle. Since the proton is not a point particle the charge radius of the proton depends on the charge distribution (the form factor) of the partons inside the proton. Since this form factor is a non-perturbative quantity in QCD it cannot be calculated by using the perturbative QCD (pQCD) method but it can be calculated by using the lattice QCD method. In this paper we formulate the lattice QCD method to study the charge radius of the proton. We derive the non-perturbative formula of the charge radius of the proton from the first principle in QCD which can be calculated by using the lattice QCD method. PACS numbers: 14.20.Dh, 12.38.-t, 11.30.-j, 12.38.Gc arXiv:1908.01586v1 [physics.gen-ph] 1 Aug 2019 ∗E-Mail: [email protected] Typeset by REVTEX 1 I. INTRODUCTION By using the spectroscopic method involving the electronic hydrogen (the ordinary hy- drogen atom consisting of proton and electron) the charge radius of the proton is measured to be 0.8768 ×10−15 meter. Similarly by using the electron-proton scattering method the charge radius of the proton is measured to be 0.8775 ×10−15 meter which is consistent with the spectroscopic method. The CODATA-2014 world average value of the charge radius of the proton by using the electrons, i.
    [Show full text]
  • Proton Radius Puzzle and Large Extra Dimensions Wei-Tou Ni (倪維斗) National Tsing Hua University
    School & Symposium on Precision Measurement and Gravity Experiment, Taipei, 1/24-2/2/1983 Proton radius puzzle and large extra dimensions Wei-Tou Ni (倪維斗) National Tsing Hua University Based on (i) arXiv:1303.4885, Proton radius puzzle and large extra dimension, Li-Bang Wang, W-T Ni (ii) Atomic transition frequencies and extra dimensions Talk given by Li-Bang Wang (王立邦) in Workshop on the Microscopic Origin of Gravity & related topics, NCTS, Hsinchu, 1/26-27/2013 Atomic transitions frequencies and extra dimensions, talk given by Li-Bang Wang Cosmic Bubbles, Spacetime Foams Primordial Black Holes, Worm Holes, White Holes, Primordial Soup & Transmutation of Dimensions in the Planckian World Introduction “Frequency”: the physics quantity that can be measured very precisely Magnetic moment of electron, ge (exp) = 2.0023193043617(15) Rydberg constant = 109,737.31568639(91) −27 EDM of electron |de| < 1.05×10 e·cm The best atomic clock f/f = 8×10-18 [1] G. Gabrielse et al., Phys. Rev Lett. 97, 30802 (2006) [2] Th. Udem et al., Phys. Rev. Lett. 79, 2646 (1997) [3] JJ Hudson et al., Nature 473, 493 (2011) [4] CW Chou et al., Phys. Rev. Lett. 104, 070802 (2010) G measurements Fixler et al., Science 315, 74-77 (2007) Atom Torsion Free fall with interferometer balance laser tracking G = 6.673 84(80) x 10-11 G/G ~ 100 ppm Outline Gravity problem Extra dimension and ADD model Precision atomic measurement Recent examples Proton Radius Puzzle Other possible tests Conclusion What’s wrong with Gravity? In Planck scale: F. Wilczek, Physics Today Oct.
    [Show full text]
  • Proton Radius Puzzle
    Proton radius puzzle Jan C. Bernauer COFI workshop - San Juan - May 2018 100 years of protons! Proton is a composite system. It must have a size! How big is it? What is ”stuff”? The matter around us is described by non-perturbative quantum chromodynamics. npQCD is hard. Simplest QCD system to study: Protons 2 Proton is a composite system. It must have a size! How big is it? What is ”stuff”? The matter around us is described by non-perturbative quantum chromodynamics. npQCD is hard. Simplest QCD system to study: Protons 100 years of protons! 3 What is ”stuff”? The matter around us is described by non-perturbative quantum chromodynamics. npQCD is hard. Simplest QCD system to study: Protons 100 years of protons! Proton is a composite system. It must have a size! How big is it? 4 Two transitions for two unknowns: Rydberg constant R 1S Lamb shift = radius1 ) Direct Lamb shift 2S 2P ! Motivation: ”Normal” Hydrogen Spectroscopy 8S 4S 3S 3D 2S 2P R1 L1S EnS u 2 + 3 − n n 2 1S L1S = 8171:626(4) + 1:5645 rp MHz 5 Direct Lamb shift 2S 2P ! Motivation: ”Normal” Hydrogen Spectroscopy 8S 4S 3S 3D 2S 8S 2S 8D ! ! 2S 2P R1 L1S EnS u 2 + 3 − n n Two transitions for two unknowns: Rydberg constant R 1 1S 2S 1S Lamb shift = radius ! ) 2 1S L1S = 8171:626(4) + 1:5645 rp MHz 6 Motivation: ”Normal” Hydrogen Spectroscopy 8S 4S 3S 3D 2S 2P 2S ! 2P R1 L1S EnS u 2 + 3 − n n Two transitions for two unknowns: Rydberg constant R 1S Lamb shift = radius1 ) Direct Lamb shift 2S 2P ! 2 1S L1S = 8171:626(4) + 1:5645 rp MHz 7 ”Normal” Hydrogen Spectroscopy Results 8 Elastic lepton-proton scattering Method of choice: Lepton-proton scattering Point-like probe No strong force Lepton interaction ”straight-forward” Measure cross sections and reconstruct form factors.
    [Show full text]
  • Arxiv:2009.09867V2 [Hep-Ph] 16 Nov 2020 Charge Radius Puzzle, See E.G
    Dark Matter as a Solution to Muonic Puzzles Maxim Perelstein, Yik Chuen San Laboratory for Elementary Particle Physics, Cornell University, Ithaca, NY 14853, USA (Dated: November 17, 2020) We propose a simple model in which dark matter particle exchanges mediate a new quantum force between muons and nucleons, resolving the proton charge radius puzzle. At the same time, the discrepancy between the measured anomalous magnetic moment of the muon and the Standard Model prediction can be accommodated, and thermal relic abundance of the dark matter candidate is consistent with observations. The dark matter particle mass is in the MeV range. We show that the model is consistent with a variety of experimental and observational constraints. I. INTRODUCTION Observational evidence for the existence of dark matter (DM) is overwhelming. While DM comprises most of the matter in today's universe, and contributes about 20% of the total energy density, there is no known elementary particle that can account for it. Many candidate theories have been proposed, extending the Standard Model (SM) of particle physics to include one or more dark matter particles. In many theories, DM particles have potential experimental or observational signatures going beyond the purely gravitational effects that have been observed. However, no non-gravitational signature of DM has been conclusively established so far. FIG. 1: One loop diagram involving exchange of dark mat- In this paper, we propose that dark matter particles are ter particle χ that induces a new force between muons and directly responsible for explaining a long-standing puzzle protons. in particle physics, the proton charge radius anomaly.
    [Show full text]
  • PROTON RADIUS PUZZLE and LARGE EXTRA DIMENSIONS 1. Introduction the Charge Radius of the Proton Has Drawn a Lot of Theoretical
    PROTON RADIUS PUZZLE AND LARGE EXTRA DIMENSIONS LI-BANG WANG* Department of Physics, National Tsing Hua University, Hsinchu,30013,Taiwan [email protected] WEI-TOU NI Department of Physics, National Tsing Hua University, Hsinchu,30013,Taiwan [email protected] Received Day Month Day Revised Day Month Day We propose a theoretical scenario to solve the proton radius puzzle which recently arises from the muonic hydrogen experiment. In this framework, 4 + n dimensional theory is incorporated with modified gravity. The extra gravitational interaction between the proton and muon at very short range provides an energy shift which accounts for the discrepancy between spectroscopic results from muonic and electronic hydrogen experiments. Assuming the modified gravity is a small perturbation to the existing electromagnetic interaction, we find the puzzle can be solved with stringent constraint on the range of the new force. Our result not only provides a possible solution to the proton radius puzzle but also suggests a direction to test new physics at very small length scale. Keywords: proton size puzzle; large extra dimensions; Lamb shift; muonic hydrogen; atomic spectroscopy. PACS Nos.: 04.50.-h, 14.20.Dh, 31.30.jf, 31.30.jr, 42.62.Fi 1. Introduction The charge radius of the proton has drawn a lot of theoretical interest since a very precise Lamb shift measurement has been performed on muonic hydrogen.1 The measured rms charge radius rp = 0.8418(7) fm is significantly smaller than the CODATA value of 0.8775(39) fm, which is a combined result
    [Show full text]