New Physics Summer Camp on ILC Hitoshi Murayama (Berkeley, Kavli IPMU Tokyo) September 25, 2020
東京大学 2004.2.12 シンボルマーク+ロゴタイプ 新東大ブルー
基本形
漢字のみ
英語のみ Apology
• I volunteered to give a talk but for some reason totally forgot about it.
• I don’t have a dedicated assistant any more… • and yesterday was 32th anniversary • Thank you for rescheduling the talk for today! Disclaimer
• I am trying to find new ways to exploit ILC for new physics searches. The content of the talk is somewhat sketchy and qualitative. You are warned that what I will discuss should not be taken literally. Your mileage may vary.
Yes Higgs exists!
ATLAS-CONF-2016-067
200 Data ATLAS Preliminary CMS-HIG-16-041 Let there be light -1 Background 180 s = 13 TeV, 13.3 fb Signal + Background -1 H→γγ, m = 125.09 GeV Preliminary 35.9 fb (13 TeV) H CMS What160 isSignal my
weights / GeV S/B weighted sum of Data ∑ event categories 100 140 H(125) ggH VBF WH ZH ttH bbH tHjb tWH production mode? qq→ZZ, Zγ* 120 80 gg→ZZ, Zγ* ATLAS Simulation Preliminary H→ γγ s =13 TeV 100 Z+X Events / 4 GeV ttH leptonic 80 ttH hadronic H → ZZ has high resolution and large S/B. An 60 VH dileptons event categorization60 is performed based on the VH leptonic 40 VH MET different production modes (number of leptons, 40 VH hadronic tight jets, b-jets20 and MET) and ME based discriminants VH hadronic loose VBF tight sensitive0 to signal and background kinematics 20 10 VBF loose ggH fwd high-p Tt 5 ggH fwd low-p Tt 0 80 100 200 300 400 500 700 900 ggH central high-p 0 Tt 7 exclusive categories ggH central low-p weights - bkg m (GeV) Tt 4l 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 ∑ −for5 the main Higgs production modes Fraction of each signal process per category CMS110Preliminary 120 130 35.9140 fb-1 (13 TeV) 150 160 CMS Preliminary 35.9 fb-1 (13 TeV) ggH 4e untagged VH-hadr. tagged Jónatan PiedraVH-lept. tagged Untagged 39.68 exp. events mγγ [GeV] 4 VBF-1j tagged VBF µ VH-MET tagged WH, W X 2e2µ VBF-2j tagged ttH tagged 1.2
→ VBF-1jet 1 9.44 exp. events WH, W
l Events / bin
→ ν kin bkg tagged High resolution channel despite the small branching ratio (0.23% @ 125.09 GeV).ZH, Z→ X D 1 VBF-2jet 4.19 exp. events ZH, Z→2l 0.8 Diphoton events fall in exclusive ttH, VH, tagged VBF and untagged categories, tandtH, tt→ 0l+X 0.8 ttH, tt→1l+X an unbinned combined maximum likelihoodVH-hadronic 2.03fit exp.is eventsapplied on m tagged γγ ttH, tt→2l+X 0.6 0.6 VH-leptonic 0.36 exp. events tagged 14 0.4 0.4 VH-MET 0.12 exp. events tagged 0.2 0.2 ttH tagged 0.50 exp. events 0 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 100 110 120 130 140 150 160 170 5 signal fraction m4l (GeV) Standard Model
Are we done? ©Particle Fever 5 Some exclusion limits
0 ~-g ~g production, ~g → qq χ∼ 1
σ = 10% 2500 ATLAS Simulation Preliminary bkg [GeV] 0 1 ∼ χ L dt = 300, 3000 fb-1, s = 14 TeV m ∫ 0-lepton combined 2000 ATLAS 20.3 fb-1, s = 8 TeV, 95% CL 95% CL limit, 3000 fb-1, 〈 µ 〉 = 140 95% CL limit, 300 fb-1, 〈 µ 〉 = 60 5σ disc., 3000 fb-1, 〈 µ 〉 = 140 1500 5σ disc., 300 fb-1, 〈 µ 〉 = 60
1000
Decay forbidden
Erez Etzion, Tel Aviv University Lepton Photon 2019 500 18
0 500 1000 1500 2000 2500 3000 m~g [GeV]
HOME PAGE TODAY'Sbeen PAPER VIDEOthereMOST POPULAR beforeU.S. Edition hmurayama Help Search All NYTimes.com Science
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315 Physicists Report Failure In Search for Supersymmetry MOST EMAILED RECOMMENDED FOR YOU By MALCOLM W. BROWNE articles viewed sleptogenesis Published: January 5, 1993 56 recently All Recommendations Three hundred and fifteen physicists worked on the experiment. FACEBOOK 1. LETTER TWITTER More to the Story on Arab Blacks Their apparatus included the Tevatron, the world's most powerful particle accelerator, as well as a $65 million detector weighing as GOOGLE+ 2. North Korea Claims Its Nuclear Arsenal Is Just a ‘Deterrent’ much as a warship, an advanced new computing system and a host of EMAIL other innovative gadgets. SHARE 3. North Korea Expels BBC Journalists Over Coverage But despite this arsenal of brains and technological brawn assembled PRINT
at the Fermilab accelerator laboratory, the participants have failed to REPRINTS 4. Republicans Return to Congress Facing find their quarry, a disagreeable reminder that as science gets harder, Unavoidable Issue: Donald Trump even Herculean efforts do not guarantee success.
5. EDITORIAL In trying to ferret out ever deeper layers of nature's secrets, scientists are being forced to Mangia! Signore: Italian Court Spares accept a markedly slower pace of discovery in many fields of research, and the consequent Hungry Shoplifter rising cost of experiments has prompted public and political criticism. 6. North Korean General, Thought to Be Executed, Resurfaces To some, the elaborate trappings and null result of the latest Fermilab experiment seem to
typify both the lofty goals and the staggering difficulties of "Big Science," a term coined in 7. Q. and A.: Jeremy Brown on the Cultural 1961 by Dr. Alvin M. Weinberg of Oak Ridge National Laboratory. Some regard such Revolution at the Grass Roots failures as proof that high-energy physics, one of the biggest avenues of big science, is fast approaching a dead end. 8. WHITE HOUSE LETTER Obama Weighs Visiting Hiroshima or Nagasaki Others call the latest experiment a useful, though inconclusive, step toward gauging the ultimate basis of material existence. The difficulty of science is increasing exponentially as 9. THE UPSHOT Where Democrats Like Hillary Clinton the scientists grope toward ultimates, they point out, and particle physicists believe that Least (Besides Vermont) society must accept the smaller increments and higher costs of progress, if progress is to continue. 10. Turkish Border Guards Accused of Attacking Syrian Refugees The paper reporting results of the latest big experiment appeared Dec. 14 in the prestigious journal Physical Review Letters. The names of the 315 scientists whose work Go to Your Recommendations » What’s This? | Don’t Show contributed to the paper, arranged in alphabetical order, occupied an entire page -- more than one-fifth the overall length of the report. Following this top-heavy opening, the paper concluded in essence that the scientists had failed to find what they were looking for.
The particle accelerator used in the hunt for whimsically-named squarks and gluinos, hypothetical particles postulated by the popular but unproved theory of "supersymmetry," was the Fermilab Tevatron at Batavia, Ill. A conspicuous example of big science, this giant instrument was completed in 1983 as a $130 million upgrade of an existing accelerator.
The Tevatron whirls counter-rotating bunches of protons and antiprotons around a ring four miles in circumference, smashing protons and antiprotons together at a combined energy of 1.8 trillion electron-volts.
But accelerating particles is useless unless the results of their collisions can be observed and studied, and to do this, scientists associated with Fermilab built a gigantic accessory for the Tevatron: the C.D.F., for "Collider-Detector at Fermilab," which itself cost more than $65 million.
The 315 scientists taking part in the "C.D.F. Collaboration" use this detector in somewhat the way a builder might use a succession of sieves to separate sand of varying degrees of coarseness. Instead of sand particles, however, the detector is rigged to record the passage of various kinds of elementary particles created by the collisions of protons and antiprotons. Better Late Than Never
Even mSUSY~10 TeV ameliorates fine-tuning from 10–36 to 10–4 lore
• LHC has not discovered any new physics • ILC energy is much lower than LHC • ILC will never discover new particles • focus on deviation from SM in precision measurements = indirect probe
• maybe unusually difficult case at LHC? R-parity violation compressed spectrum disappearing tracks clever analysis
clever analysis precision Higgs, flavor HL-LHC ILC!
10 ADLO (pre.) Higgsino - MSSM
ATLAS-model dependent (CONF-2019-014) M (GeV) Δ ILC500 1
ATLAS-disappearing track (PHYS-PUB-2017-019)
10−1
100 150 200 250 + M ∼χ (GeV) 1
Figure 11: Comparison of the 1± mass limits for the Higgsino-like case for LEP, ILC500 and Figure 4: decay length, computed by SPheno, as a function of theLHC [12][13].mass The diference ATLAS results between shown for the region with mass di↵erences above 1 GeV are 1± arXiv:2002.01239model dependent. e 1 and the LSP. An exponential increase for M less than the ⇡ mass is observed. The smaller beam size and the better vertex detector could allow the observation of the • e decay vertex of the chargino even for soft events,e which would allow to soften the ISR Two dimensional plots of the number of background events andrequirement the observed upper limits Results for low sfermion masses are shown, since the aim of the study was to make it as general as for the 1± pair production cross section as a function of the 1± masspossible and and search the for the mass worst-case. di However↵erence it has to be remarked that low sfermion masses were not taken into account in the LEP analysis. They would definitely a↵ect the topologies under are shown in Fig. 5, for one of the studied scenarios. One can observestudy and make there possible thatthe sfermion even production, if the a↵ecting the results. It is also important to remark that the drop in the cross sections due to the low sfermion masses depends on the beam backgrounde is lower in the soft events region, the cross-sectione limitsenergy and are could significantly be shifted or reduced if stronger the sneutrino masses result to be in that critical point. From our study, we conclude that at the ILC either exclusion or discovery of 1± is expected there. This is due to the ISR photon required in the trigger, whichup reducesto masses close tothe the kinematic e ciency limit for any by mass up di↵erence and any mixing. Further studies to two orders of magnitude. This conclusion applies to both scenariosusing the under simulation study. of the detector for estimating the limits are foreseen. e Figure 6 shows the mass limits computed at 95% CL in the LEP studies. One observes that the worst-case scenario corresponds to the region with soft events, again due to the trigger requirements. 10 The results from the LEP studies described in this section were extrapolated to the ILC conditions. The extrapolated limits are first presented for the region with ⇡ mass < M< 3 GeV, the worst-case scenario. The limits are extrapolated taking only the dependence of the cross section on the luminosity into account. Therefore the square root of the ratio between the accumulated LEP luminosity, 800 pb 1, and the one planned for the 500 GeV ILC run ⇡ with polarisations P (e ,e+)=( 80%, +30%), 1.6 ab 1, is applied as a factor between LEP and ILC limits, i.e. Limit = Limit 0.848 10 3/1.6. The expected increase of the ILC LEP ⇥ ⇥ signal/background ratio and detector e cienciesp and the absence of trigger at the ILC would decrease the cross-section limits. Corrections due to these factors are however not taken into account in this study. Results for the extrapolation in the region with M>3 GeV will also be presented.
5 Five evidences for physics beyond SM • Since 1998, it became clear that there are at least five missing pieces in the SMPlanck Collaboration: Cosmological parameters • non-baryonic dark matter • neutrino mass • dark energy • apparently acausal density fluctuations • baryon asymmetry We don’t really know their energy scales...
Fig. 1. Planck foreground-subtracted temperature power spectrum (with foreground and other “nuisance” parameters fixed to their best-fit values for the base ⇤CDM model). The power spectrum at low multipoles (` = 2–49, plotted on a logarithmic multi- pole scale) is determined by the Commander algorithm applied to the Planck maps in the frequency range 30–353 GHz over 91% of the sky. This is used to construct a low-multipole temperature likelihood using a Blackwell-Rao estimator, as described in Planck Collaboration XV (2013). The asymmetric error bars show 68% confidence limits and include the contribution from un- certainties in foreground subtraction. At multipoles 50 ` 2500 (plotted on a linear multipole scale) we show the best-fit CMB spectrum computed from the CamSpec likelihood (see Planck Collaboration XV 2013) after removal of unresolved foreground com- ponents. The light grey points show the power spectrum multipole-by-multipole. The blue points show averages in bands of width ` 31 together with 1 errors computed from the diagonal components of the band-averaged covariance matrix (which includes contributions⇡ from beam and foreground uncertainties). The red line shows the temperature spectrum for the best-fit base ⇤CDM cosmology. The lower panel shows the power spectrum residuals with respect to this theoretical model. The green lines show the 1 errors on the individual power spectrum estimates at high multipoles computed from the CamSpec covariance matrix. Note the change± in vertical scale in the lower panel at ` = 50.
3 where is dark matter? 10 10 10 10 10 10 10 10 10 mass –30 –20 –10 10 20 30 40 50 0 [GeV]
to fluffy preheating Q-balls mirolensing etc 10 10 moduli w/ 10
–10 mass vector 6 0 mediation [GeV] gravitino WIMP non-thermal SIMP defects
QCDaxion ILC sterileneutrino asymmetric DM asymmetric only ideas I had worked on Where is new physics?
15
• light new physics must be neutral under SM
SU(3)CxSU(2)LxU(1)Y = hidden H†H = OL O⌫ +¯⌫ HL L hidden R R hidden Higgs quarks sector sector leptons
µ⌫ = ✏F 0 F L µ⌫
a a µ⌫ a = Ohidden + Fµ⌫ F + mf ff¯ L fa fa fa e Introduction Higgs to invisible BSM scalar mediator Comparison to direct detection Higgs portal, plot for direct searches ] 2 ATLAS Preliminary • Limits on BR can be translated to −39 −39 [cm 10 Binv < 0.11 10 s = 13 TeV, 139 fb-1 limits in the DM-nucleon plane All limits at 90% CL arXiv:1708.02245 -nucleon −41 Higgs Portal Other experiments −41 10 10
WIMP Scalar WIMP DarkSide-50 σ direct detection limits Caveat:Majorana EFT validity WIMP LUX in Higgs-DM −43 PandaX-II −43 10 interaction not 10
guaranteed beyond Xenon1T HL-LHC 45 45 − −
HL-LHC 10 10
HL-LHC −47 −47 10 10 e + 2 3 4 e 1 10 10 10 10 – – m [GeV] e+e WIMP scalar WIMP Majorana WIMP
Caterina Doglioni - 2019/05/13 - European Strategy Update 24 Z2 twin SM SM
Higgs mixing
SU(2) x U(1) SU(2) x U(1)
SU(3) SU(3) 6YKP*KIIU
#NN02YKVJKP.*%TGCEJKU5/PGWVTCN
20)$*KIIUECPEGNCVKQP
OKTTQTVQR %JCTIGFWPFGT 5/ VQR OKTTQT3%&3'& In Mirror Twin Higgs models, the one loop quadratic divergences that contribute to the Higgs mass are cancelled by twin sector states that carry no charge under the SM gauge groups. H
Discovery of these states at LHC is therefore difficult. May explain null results. Roni Harnik and Zackaria Chacko, JHU workshop 2017 in Budapest Antisymmetric Matters genesis
Nell Hall, Thomas Konstandin, HM, Robert McGehee arXiv:1911.12342 Electroweak Baryogenesis
• First-order phase transition • Different reflection probabilities for tL, tR • asymmetry in top quark • Left-handed top quark asymmetry partially converted to lepton asymmetry via anomaly • Remaining top quark asymmetry becomes baryon v 0 asymmetry need varying CP phase inside tL • t L the bubble wall (G. Servant) v≠0 R fixed KM phase doesn’t help • tL • need CPV in Higgs sector t
ARTICLE https://doi.org/10.1038/s41586-018-0599-8 • baryon asymmetry limited by the sphaleron rate Improved limit on the electric dipole moment of the electron � ~ 20 �W5 T ~ 10–6 T ACME Collaboration*
The standard model of particle physics accurately describes–29 all particle physics measurements made so far in the laboratory. However, it is unablede to≤ answer 1.1 many× questions10 that arise e fromcm cosmological observations, such as the nature of dark matter and why matter dominates over antimatter throughout the Universe. Theories that contain particles and Can’t lose much more to obtain interactions beyond the standard model, such as models that incorporate supersymmetry, may explain these phenomena. • Such particles appear in the vacuum and interact with common particles to modify their properties. For example, the existence of very massive particles whose interactions violate time-reversal symmetry, which could explain the –9 cosmological matter–antimatter asymmetry, can give rise to an electric dipole moment along the spin axis of the electron. 10 No electric dipole moments of fundamental particles have been observed. However, dipole moments only slightly smaller than the current experimental bounds have been predicted to arise from particles more massive than any known to exist. Here we present an improved experimental limit on the electric dipole moment of the electron, obtained by measuring the electron spin precession in a superposition of quantum states of electrons subjected to a huge intramolecular electric field. The sensitivity of our measurement is more than one order of magnitude better than any previous measurement. This result implies that a broad class of conjectured particles, if they exist and time-reversal symmetry is maximally violated, • need have masses that greatly exceed what can be measured directly at the Large Hadron Collider.
The electric dipole moment (EDM) of the electron is an asymmetric An EDM measurement with thoriumBarr-Zee monoxide charge distribution along the particle’s spin. The existence of an EDM As in ACME I, we performed our measurement in the J = 1, M = ±1 3 requires violation of time-reversal symmetry. The standard model of sublevels of the H ∆1 state of ThO, where J is the angular momentum diagrams new physics for 1st order PT particle physics predicts that the electron has such an EDM, de, but with and M is its projection along a quantization axis z (Fig. 1a). In our • 1–3 18 a magnitude far below current experimental sensitivities . However, applied electric field E = Ezz, these states are fully polarized , such that theories of physics beyond the standard model generally include new the internuclear axis n , which points from the oxygen to the thorium at the Higgs scale v=250 GeVparticles and interactions that can break time-reversal symmetry. If nucleus, is either aligned or antialigned with E. The direction of n coin- −2 these new particles have masses of 1–100 TeV c , theories typically cides with the direction of the field Eeff that acts on de. States with predict that d ≈ 10−27–10−30e cm (1e cm = 1.6 × 10−21 C m, where e opposite molecule orientation are described by the quantum number e ~ 4–8 ^ is the electron charge) —a value that is orders of magnitude larger N =sgn(E ⋅n)1=± . The direction of Eeff can be reversed either by than the standard model predictions, which is now accessible by reversing the laboratory field E or by changing the state N =±1 used experiment1,9. Here we report the result of the ACME II experiment, in the measurement; each of these approaches allows us to reject a wide 19–21 –3 an improved measurement of de with sensitivity over 10 times better range of systematic errors . CP violation×efficiency ≥10 1,9 • than the previous best measurement, ACME I . This was achieved by The electron spin, s, is along the spin of the molecular state, S. We improving the stateem preparation, experimental1 geometry, fluorescence measure the energy difference between states with M = ±1 (which cor- collection and control of systematice uncertainties. Our measurement, d respond to S being aligned or antialigned with Eeff; Fig. 1a), which −30 22 e = (4.3 ± 3.1stat ± 2.6syst) × 10 e cm (‘stat’, statistical uncertainty; ‘syst’, contains a term proportional to U. To do so, we prepare an initial coher- de systematic uncertainty), is consistent with zero andsin corresponds to=1 an ent superposition.6 of M10 = ±1 states, whiche correspondscm to sin the spin S 2−29 2 2 upper limit(16 of |de| < 1.1⇡ × 10 )e cm atv 90% confidence. This result being aligned with a fixed direction in the x–y plane (Fig. 2). The
*A list of participants and their affiliations appears at the end of the paper.
18 OCTOBER 2018 | VOL 562 | NAT U RE | 355 © 2018 Springer Nature Limited. All rights reserved. Anomaly!
• W and Z bosons massless at high temperature • W field fluctuates just like in thermal plasma • solve Dirac equation in the presence of the fluctuating W field Δq=Δq=Δq=ΔL _ τ(3He→e+μ+ντ)~10150yrs Sakharov Conditions
• Standard Model may have all three ingredients • Baryon number violation • Electroweak anomaly (sphaleron effect) • CP violation • Kobayashi–Maskawa phase J ∝ det[M † M , M † M ]/T 12 ~ 10–20≪10–10 • Non-equilibrium u u d d EW • First-order phase transition of Higgs requires mh < 75 GeV • Experimentally testable? dark sector SM Ngen=1 Ngen=3 2 Higgs doublets with CPV Higgs 1st order PT mixing
SU(2)Bdark= xL U(1)dark SU(2) x U(1) heavy leptons νR play role of LSM→BSM top quark
SU(3) SU(3) light u, d
γ’ – γ mixing n, p, π– π0 e+e– asymmetric dark matter I Bdark Ldark
BSM II LSM Bdark Ldark
BSM III Bdark LSM
36 97 If MN>Tsphaleron BSM = Bdark,LSM = Bdark mn'=1.58 GeV
terrestrial SN1987A LIGO 10-7 O1 ET LISA O2 O5 10-9 T=200 GeV 2 T=2TeV h 10-11 T=500 TeV GW 10-13 10-15 BBO 10-4 10-2 1 102 104 f (Hz) 2 2 ps mZ Mh Z EZ = 1+ e+ 2 s s ✓ ◆ h h’ π+ γ’ ε e– ε π– γ’ ε γ e– e+ Chinese Physics C Vol. 41, No. 6 (2017) 063102 ¯ + + + + (bb)(⌧ ⌧ ), (⌧ ⌧ )(⌧ ⌧ ), (jj)( ), and ( )( )de- jj + /E T, ⌧ ⌧ + /E T. For the Higgs invisible decays, we cay channels. For a decay topology of h 2 3 4 take the best limits in the running scenario ECFA16-S2 where intermediate resonances are involved,! we! choose! amongst the Zh associated production and VBF search the lightest stable particle mass to be 10 GeV, the mass channels [12–14]. splitting to be 40 GeV and the intermediate resonance For the Higgs invisible decays at lepton colliders, we ¯ mass to be 10 GeV, which applies to (bb)+/E T,(jj)+/E T, quote the limits from current studies [16–18]. These lim- + (⌧ ⌧ )+/E T. For a decay topology of h 2 (1+3), we its do not depend on the invisible particle mass using the choose the lightest stable particle mass to! be! 10 GeV and recoil mass technique at lepton colliders. Higgs →dark¯ sector →SM the mass splitting to be 40 GeV, which applies to bb+/E T, 95% C.L. upper limit on selected Higgs Exotic Decay BR 1 HL-LHC 10-1 CEPC ILC(H20) ) FCC-ee 10-2 Exotics h -3 ( 10 BR 10-4 10-5 ME (bb)+ (jj)+ ( )+ bb+ jj+ME +ME (bb (cc)( (jj)(jj (bb)( ( )( (jj)( ( T ME ME ME ME T )(bb cc ) ) ) )( T T T T T ) ) ) ) Fig. 12. The 95% C.L. upper limit on selected Higgs exotic decay branching fractions at HL-LHC, CEPC, ILC and FCC-ee. The benchmark parameter choices are the same as in Table 3. We put several vertical lines in this figure to divide di↵erent types of Higgs exotic decays. From this summary in Table 3 and the correspond- ing energy is less impressive than for those with missing ing Fig. 12, we can clearly see the improvement in exotic energy. Furthermore, as discussed earlier, leptons and decays from the lepton collider Higgs factories. These photons are relatively clean objects at the LHC and the exotic Higgs decay channels are selected such that they sensitivity at the LHC on these channels will be very Zhen Liu, Lian-Tao Wang, Hao Zhang, arXiv:1612.09284 are hard to be constrained at the LHC but important for good. Future lepton colliders complement the HL-LHC probing BSM decays of the Higgs boson. The improve- for hadronic channels and channels with missing ener- ments on the limits of the Higgs exotic decay branch- gies. ing fractions vary from one to four orders of magni- There are many more investigations to be carried tude for these channels. The lepton colliders can im- out under the theme of Higgs exotic decays. For our + prove the limits on the Higgs invisible decays beyond the study, we take the cleanest channel of e e ZH with + ! HL-LHC projection by one order of magnitude, reach- Z ` ` and h exotics up to four-body final state, ing the SM invisible decay branching fraction of 0.12% but! further inclusion! of the hadronic decaying spectator from h ZZ⇤ ⌫⌫⌫¯ ⌫¯ [56]. For the Higgs exotic de- Z-boson and even invisible decays of the Z-boson would cays into! hadronic! particle plus missing energy, (b¯b)+/ definitely improve the statistics and consequently result + ET,(jj)+/E T and (⌧ ⌧ )+/E T, the future lepton colliders in better limits. As a first attempt to evaluate the Higgs improve on the HL-LHC sensitivity for these channels by exotic decay program at future lepton colliders, we do roughly four orders of magnitude. This great advantage not include the case of very light intermediate particles benefits a lot from low QCD background and the Higgs whose decay products will be collimated, but postpone tagging from recoil mass technique at future lepton col- this for future study when the detector performance is liders. As for the Higgs exotic decays without missing more clearly defined. There are many more exotic Higgs energy, the improvement varies between two to three or- decay modes to consider, such as Higgs decaying to a ders of magnitude, except for the one order of magnitude pair of intermediate particles with un-even masses [25], improvement for the ( )( ) channel. Being able to re- Higgs CP property measurements from its decay di↵eren- construct the Higgs mass from the final state particles tial distributions [57–60], flavor violating decays, decays at the LHC does provide additional signal-background to light quarks [61], decays into meta-stable particles, discrimination power and hence the future lepton collid- and complementary Higgs exotic productions [62]. Our ers improvement on Higgs exotic decays without miss- work is a first systematic study evaluating the physics 063102-12 2 2 ps mZ Mh Z EZ = 1+ e+ 2 s s ✓ ◆ – h l νR e– j j νR j l– j neutrino portal l– e+ νR j Z j e– νL e+ νL W l+ e– νR j j 70 2 |U| CCFR(NBB) OPAL CHARM-II L3 SIN KEK DELPHI LBL CHARM DELPHI Z. Phys. C 74, 57–71 (1997) BEBC Fig. 11. Limits at the 95% CL on the mixing matrix el- 2 ement U as a function of the νm mass for the various | | experiments referenced in the text. The limits shown for the present analysis correspond to those obtained combin- 2) m (GeV/c ing the short–lived and long–lived νm analysis ) -1 Weak decay (GeV Electromagnetic decay Λ / * νν Z c Fig. 12. Upper limits at 95% CL on the parameter L3 c 0 /Λ as a function of mν from the present anal- Z ν∗ν ∗ ALEPH L3 ysis. For comparison, previous results from the LEP ex- DELPHI periments referenced in the text are also shown. The full curves (‘weak decay’) correspond to the limits for the DELPHI standard SU(2) U(1) current, allowing only weak decays. × The dashed curves (‘electromagnetic decay’) are the limits for ν∗ γν, the dominant decay mode when the γνν∗ 2 → m ν * (GeV/c ) coupling exists Acknowledgements. We are greatly indebted to our technical collaborators L3 Collaboration, O. Adriani et al., Phys. Lett. B295 (1992) 371; and to the funding agencies for their support in building and operating the CHARM II Collaboration, P. Vilain et al., Phys. Lett. B295 (1992) 371 DELPHI detector, and to the members of the CERN-SL division for the 7. ALEPH Collaboration, D. Buskulic et al., Phys. Lett. B313 (1993) 312; excellent performance of the LEP collider. We thank A. Santamar´ıa from ALEPH Collaboration, D. Buskulic et al., Phys. Lett. B334 (1994) 224; the theoretical department of Valencia University for his helpful comments ALEPH Collaboration, D. Buskulic et al., Zeit. Phys. C66 (1995) 3 and suggestions concerning the theoretical aspects of the paper and R. Kleiss 8. A. M. Cooper-Sarkar et al., Phys. Lett B160 (1985) 207; from the theoretical department at NIKHEF for his help in understanding J. Dorenbosch et al., Phys. Lett. B166 (1986) 473; some aspects of the program EXCALIBUR. S. R. Mishra et al., Phys. Rev Lett. 59 (1987) 1397; M. E. Duffy et al., Phys. Rev. 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Phys B424 (1994) 308; dark sector SM Ngen=1 Ngen=3 2 Higgs doublets with CPV Higgs 1st order PT mixing SU(2)Bdark= xL U(1)dark SU(2) x U(1) heavy leptons νR play role of LSM→BSM top quark SU(3) SU(3) light u, d γ’ – γ mixing n, p, π– π0 e+e– If the asymmetry goes from SM to dark sector, dark baryons are ~50 GeV 2 ps Minv γ E = 1 e+ 2 s ✓ ◆ γ γ’ e– ε ρ’,φ’,ψ’,Υ’ Yonit Hochberg, Eric Kuflik, HM, arXiv:1512.07917, 1706.05008 1 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-1 1 101 102 103 Dark Spectroscopy 103 102 10 1 0.1 1.0 1.2 1.4 1.6 1.8 2.0 Dark Spectroscopy 105 104 103 102 10 1 4.0 4.2 4.4 4.6 4.8 5.0 Yonit Hochberg, Eric Kuflik, HM FASER@LHC FASER@LHC Mathulsa@LHC Figure 2. Engineering details of the partially excavated structure that would house MATHUSLA. Figure 3. MATHUSLA@CMS geometry relative to the CMS collision point. backscattering. The total height of 40 m includes a 25 m LLP decay volume, 21 m of which ⇠ ⇠ would be excavated, and 12 m above the surface that hosts the tracker and the crane system used for assembly and maintenance. The layout of the the building that houses the 100 m 100 m experimental area and the adjacent ⇥ 30 m 100 m adjacent area for the detector assembly is shown in Figure 1. The structure, which is ⇥ located on the surface near the CMS IP fits well on CERN owned land. Having a large part of the decay volume underground brings it closer to the IP, which increases the solid angle in the acceptance –4– Mathulsa@LHC 10-4 10-6 10-8 2 Sin 10-10 10-12 MATHUSLA @ CMS 10-14 0.05 0.10 0.50 1 5 10 mS/GeV (a) a long-lived scalar mixed with Higgs to redo these, just output plot in the same way, then give new plot pdf the same dimensions & coordinates as the aligned one (b) (c) Figure 7. Purple curves: sensitivity of MATHUSLA@CMS for a singlet scalar LLP s mixing with Higgs mixing angle ✓. (a) Assuming production in exotic B, D, K meson decays only. (b) Assuming additional production in exotic Higgs decays with Br(h ss)=0.01. Figures (a) and (b) are reproduced from the PBC ! BSM Working Group report [19] with the purple MATHUSLA@CMS curves added. This shows sensitivity of various other existing and proposed experiments, as well as the old MATHUSLA200 benchmark estimates (yellow curves). (c) Same scenario as (b) but showing the entire MATHUSLA sensitivity due to h ss decays. ! the advantage gained by the high LHC energy even when searching for very light LLPs, since they can be produced in high-scale processes that are kinematically suppressed at intensity frontier ex- periments. Also shown are the expected sensitivities of other proposed experiments like FASER [4], CODEX-b [9], and SHiP [43]. Figure 8 (a) - (c) shows MATHUSLA’s reach for Heavy Neutral Leptons (HNL) that dominantly mix with only electron, muon or tau active neutrinos. These estimates are slightly improved compared to the previous results in [3, 19], since the production and decay rate calculations have been updated to agree with the latest results in [34], also adopted by e.g. [44]. The effect of this improved calculation for the old MATHUSLA200 benchmark geometry can be seen in Figure 8 (d) by noting the small differences between the dark yellow and green curves. The effect of the new MATHUSLA@CMS –8– .Py.G ul at Phys. Part. Nucl. G: Phys. J. Table 1. Projects considered in the PBC–BSM working group categorized in terms of their sensitivity to a set of benchmark models in a given mass range. The characteristics of the required beam lines, whenever applicable, are also displayed. Proposal Main physics cases Beam line Beam type Beam yield Sub-eV mass range: IAXO Axions/ALPs (photon coupling) — Axions from sun — JURA Axions/ALPs (photon coupling) Laboratory eV photons — CPEDM p, d oEDMs EDM ring p, d — 47 axions ALPs (gluon coupling) p, d — ( / 2020 LHC-FT Charmed hadrons oEDMs LHCb IP 7 TeV p — ) MeV–GeV mass range: Beacham J 010501 SHiP ALPs, dark photons, dark scalars BDF, SPS 400 GeV p 2 1020/5 years LDM, HNLs, lepto-phobic DM, NA62++ ALPs, dark photons, K12, SPS 400 GeV p up to 3 1018/year dark scalars, HNLs − 12 13 NA64++ ALPs, dark photons, H4, SPS 100 GeV e 5 × 10 eot/year dark scalars, LDM 12 13 + Lμ−Lτ M2, SPS 160 GeV μ 10 −10 mot/year + CP, CPT, leptophobic DM H2-H8, T9 ∼40 GeV π, K, p 5 × 1012/year LDMX Dark photon, LDM, ALPs eSPS 8 (SLAC) -16 (eSPS) GeV e− 1016−1018 eot/year AWAKE/NA64 Dark photon AWAKE beam 30-50 GeV e− 1016 eot/year REDTOP Dark photon, dark scalar, ALPs CERN PS 1.8 or 3.5 GeV 1017 pot MATHUSLA200 Weak-scale LLPs, dark scalar, ATLAS or CMS IP 14 TeV p 3000 fb−1 Dark photon, ALPs, HNLs FASER Dark photon, dark scalar, ALPs, ATLAS IP 14 TeV p 3000 fb−1 HNLs, B−L gauge bosons MilliQan Milli charge CMS IP 14 TeV p 300–3000 fb−1 CODEX-b Dark scalar, HNLs, ALPs, LHCb IP 14 TeV p 300 fb−1 LDM, Higgs decays >> TeV mass range: 0 19 al et KLEVER KL P42/K12 400 GeV p 5 × 10 pot /5 years ILC250: 1021 e± / year UT-HET 102, UT-15-24 Beam Dump Experiment atfixed Future Electron-Positron target, beam Colliders dump Shinya Kanemura(a),TakeoMoroi(b), Tomohiko Tanabe(c) (a)Department of Physics, University of Toyama, Toyama 930-8555, Japan (b)Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan (c)ICEPP, The University of Tokyo, Tokyo 113-0033, Japan (Dated: July, 2015) 5GeV − We propose a new beam dump experiment at future colliders withelectron(e )andpositron 50GeV (e+)beams,BDee,whichwillprovideanewpossibilitytosearchforhiddenparticles, like hidden photon. If a particle detector is installed behind the beam dump, it can detect the signal of in-flight100GeV decay of the hidden particles produced by the scatterings of e± beams offmaterials for dumping. − 125GeV We show that, compared to past experiments, BDee (in particular BDee at e+e linear collider) significantly enlarges the parameter region where the signalofthehiddenparticlecanbediscovered. High energy colliders with electron (e−) and positron Veto Detector (e+) beams, such as the International Linear Collider Shield Beam Dump (ILC) [1], the Compact Linear Collider (CLIC) [2], and Beam Future Circular Collider with e+e− beams (FCC-ee) [3], are widely appreciated as prominent candidates of future experiments. One of the reasons is that, with the dis- covery of Higgs boson at the LHC [4], detailed studies − of Higgs properties at e+e colliders are now very im- L dump L sh L dec portant [5]. In addition, e+e− colliders have sensitivity to new particles at TeV scale or below if they have elec- FIG. 1: Schematic view of BDee.Theelectron(orpositron) troweak quantum numbers. beam is injected into the beam dump from the left. Although e+e− colliders have many advantages in studying physics beyond the standard model (BSM), they can hardly probe BSM particles whose interaction is very of 1.8 m-diameter cylindrical stainless-steel high-pressure weak. We call such particles hidden particles, which ap- (10 bar) water vessels [1]. The e± beams after passing pear in various BSM models. For example, there may through the interaction point are injected into the dump, exist a gauge symmetry other than those of the stan- which absorbs the energy of the electromagnetic shower dard model (SM), as is often the case in string theory. in 11 m of water. If there exists a hidden particle, like hid- ± If the breaking scale of such a hidden gauge symmetry den photon, for example, it is produced by the e -H2O is lower than the electroweak scale, the associated gauge scattering process. In this letter, to make our discussion boson can be regarded as a hidden particle [6]. In string concrete, we consider the case where the target is H2O, theory, it has also been pointed out that there may exist although other materials may be used as a target. The axion-like particles (ALPs) [7]; they are also candidates of number of the hidden photon produced in the dump is the hidden particle. Sterile neutrino is another example. insensitive to the target material. These particles interact very weakly with SM particles, Our proposal is to install a particle detector behind − and are hardly accessed by studying e+e collisions. If the dump, with which we can observe signals of hidden − e+e colliders will be built in the future, it is desirable particles produced in the dump. The schematic picture to make it possible to study hidden particles as well. of the setup of BDee is shown in Fig. 1. The decay vol- arXiv:1507.02809v1 [hep-ph] 10 Jul 2015 In this letter, we discuss a possibility to detect hidden ume is a vacuum vessel with the length of Ldec; the signal particles at the e+e− facilities. We propose a beam dump of the hidden particle is detected if the hidden particle experiment at future e+e− colliders (BDee), in which the decays into (visible) SM particles in the decay volume. beam after the e+e− collision is used for the beam dump A tracking detector is used to detect the hidden parti- experiment. In particular, at the ILC and CLIC, the e± cle decaying into a pair of charged particles. Additional beams will be dumped after each collision, which makes detectors such as calorimeters and muon detectors may a large number of e± available for the beam dump ex- be installed to enrich the physics case. As well as the periment. Using the hidden photon, which is the gauge hidden particles, charged particles are also produced in boson associated with a (spontaneously broken) hidden the dump; rejection of those particles is essential to sup- U(1) symmetry, as an example, we show that the BDee press backgrounds. In particular, a significant amount of can cover a parameter region which has not been explored muons are produced, as we will discuss in the following. by past experiments. Thus, we expect to install shields and veto counters be- Let us first summarize the basic setup of BDee.We tween the dump and the decay volume. Additional veto simply assume the current design of the beam dump sys- counters surrounding the detector serve to reject cosmic tem of the ILC although one may consider other possi- rays. bilities. The main beam dumps of the ILC will consist To see the sensitivity of BDee, we consider a model – + e e γ’ + e shield γ’ ε γ γ sterile neutrino, etc neutrino, sterile dark photon, axion, axion, photon, dark + p e beam dump 4 the fundamental processes producing hidden particles are different. If signals of a hidden particle are discovered, discrimination of various possibilities of hidden particles may become possible by combining the results of BDee and SHiP. In summary, given the fact that a large number of e± will become available for beam dump experiment once e+e− collider starts its operation, we propose to install a particle detector behind its dump. Using the hidden photon model as an example, we have shown that the beam dump experiment at e+e− colliders, BDee, signif- icantly enlarges the discovery reach of hidden particles. To understand the potential of BDee, case studies for other hidden particles, like ALPs and sterile neutrinos, should be performed. In doing so, the full capabilities of the machine, such as the use of positrons which yield annihilation processes, and, in the case of linear colliders, FIG. 2: Contours of constant Nsig on the mX vs. ! plane the use of beam polarization, should be explored. In ad- Shinya Kanemura,for Ebeam =250(red),500(blue),and1500GeV(green), Takeo Moroi, Tomohiko Tanabe, arXiv:1507.02809dition, the discovery reach depends on the detail of the N × 21 L L taking e =4 10 , dump =11m, sh =50m,and configurations of detectors and shields. As we have dis- L dec =50m.Thedotted,solid,short-dashed,andlong- cussed, the muons produced in the dump are potential N −2 2 4 dashed lines correspond to sig =10 ,1,10,and10, serious background and hence careful designs of detectors respectively. The gray-shaded regions are already excludedby and shields are needed. These issues will be discussed past beam dump experiments [10] (light-gray) or supernova elsewhere [17]. BDee will provide a new possibility to bounds [14] (dark-gray), while SHiP experiment, if approved, will cover the yellow-shaded one [15]. probe hidden particles, and hence is worth being consid- ered seriously as an important addition to future e+e− facilities. Finally, we compare BDee with another possible hid- Acknowledgment: The authors are grateful to K. Fujii, den particle search in the future, SHiP experiment [16]. K. Nakamura, K. Oda, and T. Suehara for useful discus- The expected discovery reach of SHiP is also shown in sion. They also thank Okinawa Institute of Science and Fig. 2 for the hidden photon model. We can see that, if Technology Graduate University for their hospitality, at approved, SHiP will also cover the parameter region on which this work was initiated. This work is supported by which BDee has a sensitivity. It should be noted that Grant-in-Aid for Scientific research Nos. 23104006 (SK), SHiP is a fixed target experiment with proton beam, so 23104008 (TM), 26400239 (TM), and 23000002 (TT). [1] T. Behnke et al.,arXiv:1306.6327[physics.acc-ph]; [7] A. Arvanitaki et al.,Phys.Rev.D81,123530(2010) H. Baer et al.,arXiv:1306.6352[hep-ph];C.Adolphsen [arXiv:0905.4720 [hep-th]]. et al.,arXiv:1306.6353[physics.acc-ph];C.Adolphsenet [8] K. J. Kim and Y. S. Tsai, Phys. Rev. D 8,3109(1973). al.,arXiv:1306.6328[physics.acc-ph];T.Behnkeet al., [9] J. D. Bjorken, R. Essig, P. Schuster and N. Toro, Phys. arXiv:1306.6329 [physics.ins-det]. Rev. D 80,075018(2009)[arXiv:0906.0580[hep-ph]]. [2] L. Linssen, A. 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[physics.ins-det]. [6] L. B. Okun, Sov. Phys. JETP 56,502(1982)[Zh.Eksp. [17] S. Kanemura, T. Moroi and T. Tanabe, work in progress. Teor. Fiz. 83,892(1982)];B.Holdom,Phys.Lett.B166, 196 (1986). future upgrades ILC Nb 40MV/m 1TeV ILC Nb3Sn 100MV/m 3TeV CLIC 100MV/m 3TeV PWFA 1GV/m 30TeV ILC HZ(250 GeV) 6.75x1034 ■ (Nbunch x 2) ■ B 34 ILC HZ(250 GeV) 3.37x10 ■ ■ ■ A (Baseline, w/ polarization) Nbunch x 2 ■ ILC HZ(250 GeV) 1.35x1034 ■ (Baseline) CLIC 30 TeV Fig. 5.1: Conceptual schematic of a 30 TeV DLA e+ e- collider driven by a carrier envelope phase locked net- work of energy-efficient solid-state fiber lasers at 20 MHz repetition rate. Laser power is distributed by photonic waveguides to a sequence of dielectric accelerating, focusing, and steering elements co-fabricated on 6-inch wafers which are aligned and stabilized using mechanical and thermal active feedback systems. active feedback systems. The DLA mechanism is also equally suitable for accelerating both electrons and positrons. Exam- ple machine parameters for a DLA collider have been outlined in the Snowmass 2013 report and several other references [8,10,11,12]. In these example parameter studies, DLA meets desired luminosities with reasonable power consumption and with low beamstrahlung energy loss. 2 Summary of the ANAR 2017 Report The Advanced and Novel Accelerators for High Energy Physics Roadmap Workshop (ANAR) was held at CERN in June 2017, with the goal of identifying promising advanced accelerator technologies and establishing an international scientific and strategic roadmap toward a future high energy physics collider [13]. Four concepts were considered: laser-driven plasma wake field acceleration (LWFA), beam-driven plasma wake field acceleration (PWFA), structure-based wake field acceleration (SWFA), and dielectric laser acceleration (DLA). Dedicated working groups were convened to study each concept. The working group on DLA, co-chaired by R. J. England (SLAC), J. McNeur (FAU-Erlangen), and B. Carlsten (LANL), produced a roadmap to a DLA based collider on a 30 year time scale, as shown in Fig. 5.2. Compact multi-MeV DLA systems for industrial and scientific use are expected on a 10 year time scale. A dedicated GeV-scale multi-stage prototype system is recommended within 20 years to demonstrate energy scaling over many meters with efficiency and beam quality suitable for HEP applications. A conceptual design report is projected to commence in 2025, followed by a technical design report, with linear collider construction commencing by 2040. The DLA working group evaluated current state of the art in the field and identified both signif- icant advantages as well as technical challenges of the DLA approach as a future collider technology. Key advantages include the fact that the acceleration occurs in vacuum within a fixed electromagnetic 56 lepton vs proton (a) arXiv:2005.10289(b) Figure 1. The equivalent proton collider energy psp [TeV] required to reach the same beam-level + cross section as a µ µ collider with energy psµ [TeV] for (a) 2 1 and (b) 2 2 parton-level ! ! process, for benchmark scaling relationships between the parton-level cross sections [ˆ ]p and [ˆ ]µ + as well as for pair production of t˜t˜ and ˜ ˜ through their leading 2 2 production modes. ! we identify the kinematic threshold as ⌧ = sµ/sp, and likewise the factorization scale as µf = psµ/2. If one further assumes a relationship between the partonic cross sections, then this identification allows us to write equation 3.6 as sµ psµ [ˆ ]µ 1 ij , = . (3.7) sp 2 [ˆ ]p ⌘ Xij ✓ ◆ which can be solved⇤ numerically for sp as a function of sµ and . For various benchmark assumptions ( ) on the partonic cross sections [ˆ ]p and [ˆ ]µ, and for the parton luminosity configurations ij = gg (red) and ij = qq (blue), where q u, c, d, s is any light quark, we plot in figure 1(a) the equivalent proton collider energy 2{ } psp as a function of psµ, for a generic 2 1, neutral current process. In particular, for ! + each partonic configuration, we consider the case where the ij and µ µ partonic rates are the same, i.e., when =1(solid line) in equation 3.7, as well as when = 10 (dash) and = 100 (dash-dot). The purpose of these benchmarks is to cover various coupling regimes, such as when ij Y and µ+µ Y are governed by the same physics ( = 1) or when ! ! ij Y is governed by, say, QCD but µ+µ Y by QED ( = 10). ! ! Overall, we find several notable features. First is the general expectation that a larger pp + collider energy is needed to achieve the same partonic cross section as a µ µ collider. This follows from the fact that pp beam energies are distributed among many partons whereas + µ µ collider energies are effectively held by just two incoming partons. Interestingly, we find a surprisingly simple linear scaling between the two colliders for all ij and combinations. For the ij = qq configuration and equal partonic coupling strength, i.e., =1, we report a scaling relationship of psp 5 psµ. Under the above assumptions, ⇠ ⇥ ⇤Explicitly, we use the scipy function fsolve to carry out a brute force computation of this transcen- dental equation. We report a reasonable computation time on a 2-core personal laptop. –7– What I discussed • mass vs coupling • exotic Higgs/Z decay • dark spectroscopy • long-lived particle • beam dump • higher energies ILC • despite lack of new physics at LHC, ILC has many opportunities to discover new physics • so far emphasis on precision measurements • light dark sector: active discussions recently • standard collider mode, detectors away from IP, beam dump, fixed target • more ideas?