1115

˙ ‫঺ڀݚ‬հ

CERN SPS Λ༻͍ͨλ΢χϡʔτϦϊଌఆͱ৽෺ཧ୳ࡧɿ
SHiP ‫ܭ‬ը + DsTau/NA65 ࣮‫ݧ‬a

University of Bernɼb ‫۝‬भେֶɼc ໊‫ݹ‬԰େֶɼd ‫ذ‬ෞେֶ༗լ ত‫ و‬a ɼ༗լ ஐࢠ b ɼখদ խ޺ c ɼࠤ౻ म c ɼ٢ຊ խߒ dakitaka.ariga@lhep.unibe.chɼtomoko.ariga@cern.chɼkomatsu@ﬂab.phys.nagoya-u.ac.jpɼ
sato@ﬂab.phys.nagoya-u.ac.jpɼyohim@gifu-u.ac.jp෺ཧഎ‫ܠ‬

Λ༻͍ͯɼҎԼ 1.1-1.3 Ͱड़΂Δ෺ཧΛ௥‫͍ͯ͠ٻ‬Δɻͦ
͜Ͱ͸೔ຊͷಘҙͱ͢Δٕज़͕ੜ͖͍ͯΔɻ

1.1

λ΢χϡʔτϦϊࢄཚʹ͓͚ΔϨϓτϯ
ීวੑͷ‫ূݕ‬λ΢χϡʔτϦϊ͸ 3 ੈ୅͋ΔχϡʔτϦϊͷதͰ΋

ντ

100
80

νe

νμ

DONuT

ஶऀΒ͸ɼCERN ͷ Super Proton Synchrotron (SPS)120

σconst (×10-40 cm2/GeV)

1

60

DONuT with n=6.1 from Pythia 6(main systematic uncertainty
not included)2020 ೥ (ྩ࿨ 2 ೥) 2 ݄

SM

40
20
0

ୈ 3 ੈ୅ʹҐஔ͢Δɻͦͷੜ੒ͱ‫ݕ‬ग़͸ࠔ೉Ͱ͕͋ͬͨɼ
ۙ೥Α͏΍ͦ͘ͷ‫ݕ‬ग़ٕज़ཱ͕֬ͭͭ͋͠Δɻ͜Ε·Ͱਤ 1: 3 ੈ୅ͷχϡʔτϦϊͷ ν ɼν ฏ‫ਂۉ‬ඇ஄ੑࢄཚ൓

ʹ DONuTɼOPERAɼSuper-KɼIceCube ࣮‫͕ݧ‬λ΢Ԡஅ໘ੵ [1]ɻԣഁઢ͕ඪ४ཧ࿦͔Β༧ଌ͞ΕΔ஋ɻ

χϡʔτϦϊͷ‫؍‬ଌΛใࠂ͍ͯ͠Δɻ͜ͷதͰ΋χϡʔτϦϊৼಈΛհ͞ͳ͍௚઀తͳଌఆ͸ DONuT ࣮‫ͩݧ‬ೳੑΛ୳͢ͷ͸৺͕༂ΔࢼΈͰ͋Δɻ

͚Ͱ͋ΔɻͦΕͧΕͷଌఆ݁Ռ͸ෆఆੑ͕େ͖͘ɼλ΢ં͠΋ۙ೥ෳ਺ͷίϥΠμʔ࣮‫ʹݧ‬Αͬͯʮୈ 3 ੈ୅χϡʔτϦϊʹؔͯ͠͸ͦͷ‫ج‬ຊతͳੑ࣭ʹ͍࣮ͭͯ‫ݧ‬ͷཻࢠ͕ؔΘΔաఔͰ͸Ϩϓτϯීวੑ͕ഁΕ͍ͯΔ͔

తʹཧղ͞Ε͍ͯͳ͍ɻਤ 1 ʹ‫ࡏݱ‬ಘΒΕ͍ͯΔχϡʔ΋͠Εͳ͍ʯͱ͍͏࣮‫݁ݧ‬Ռ͕ใࠂ͞Ε͖͍ͯͯΔɻྫ

τϦϊ൓Ԡஅ໘ੵΛࣔ͢ɻϛϡʔχϡʔτϦϊʹؔͯ͑͠͹ b ΫΥʔΫΛ‫ؚ‬ΉཻࢠͷηϛϨϓτχοΫ่յʹ͓

͸ 2%ఔ౓ͱਫ਼౓Α͘ଌΒΕ͍ͯΔɻଞํɼλ΢χϡʔ͍ͯ͸λ΢΁่յ͢Δ֬཰ͱϛϡʔΦϯ΁่յ͢Δ֬཰τϦϊʹؔͯ͠͸ 50%Ҏ্ͷෆఆੑ͕͍͍ͭͯΔɻ͜

ͷൺɼR(D(∗) ) =Ε͕χϡʔτϦϊࢄཚʹ͓͚ΔϨϓτϯීวੑ‫ূݕ‬ͷ‫ݶ‬͜ͱ͕ใࠂ͞Ε͍ͯΔ [2] (BaBarɼBelleɼLHCb ͷ݁քΛܾΊ͍ͯΔɻՌΑΓɼ2019 ೥࣌఺Ͱ 3.1σ ͷ༗ҙੑ)ɻಉ༷ͷஹީ͕Ϩϓτϯීวੑ͸͜Ε·Ͱͷ൒ੈ‫ʹل‬ΘͨΔ༷ʑͳ࣮‫͞ূ࣮͍͓ͯʹݧ‬Ε͖ͯͨɻࠓͰ͸ૉཻࢠඪ४ཧ࿦ʹ͓

Γ(B→D (∗) τ ν τ )ɼ͕ཧ࿦༧૝ΑΓଟ͍
Γ(B→D (∗) lν)b → s�� (B 0 → K ∗0 ��ɼB + → K + ��) ౳͔Β΋ࣔࠦ͞Ε͍ͯΔɻ͜ΕΒͷηϛϨϓτχοΫ่յ͸ tree-level͚Δ “sacred principle”ʢ੟ͳΔ‫ݪ‬ཧʣͱͯ͠ड͚ೖΕͰͷաఔͰ͋Γੈ୅ؒͷҧ͍͸Ϩϓτϯ࣭ྔ͚ͩͱͳΔ

ΒΕ͍ͯΔɻ‫ʹݱ‬ਤ 1 ͷ݁Ռ͸ଌఆਫ਼౓ͷൣғ಺ͰීวͨΊɼͦΕͧΕͷ่յ֬཰ͷൺ͸ਖ਼֬ʹ‫͖Ͱࢉܭ‬Δɻ͜

ੑ͕੒Γཱ͍ͬͯΔͱ΋‫͑ݴ‬ΔɻϨϓτϯීวੑΛ৴͡ΕΒͷ࣮‫݁ݧ‬Ռ͸ඪ४ཧ࿦Ͱ͸આ໌͕͔ͭͣɼ“FlavorΔͳΒ͹λ΢χϡʔτϦϊ͸ͨͩͨͩଞͷ 2 ੈ୅ͱಉ͡

anomalies” ͱ‫ݺ‬͹ΕΔΑ͏ʹͳ͍ͬͯΔɻ͜ͷΞϊϚੑ࣭Ͱ͋Γɼ໨৽͍͠෺ཧ͸ͳ͍ͷ͔΋͠Εͳ͍ɻ͔͠

Ϧʔʹରͯ͠৽෺ཧͷଘࡏ͕‫ʹൃ׆‬ٞ࿦͞Εɼ·࣮ͨ‫ݧ‬͠ྺ্࢙χϡʔτϦϊ͸ৗʹզʑΛ‫͔͢ڻ‬ੑ࣭Λࣔͯ͠త༗ҙੑͷཱ֬ɾ൱ఆʹ޲͚ͯଟํ໘͔Β౒ྗ͕ͳ͞Ε͖ͨɻਓྨ͕Α͏΍֫͘ಘͨ͠λ΢χϡʔτϦϊ‫ݕ‬ग़ͷ͍ͯΔɻٕज़Λ෢‫ͯ͠ʹث‬ୈ 3 ੈ୅ͷϨϓτϯʹ৽͍͠෺ཧͷՄ͜Ε·Ͱͷใࠂ͸ཻࢠͷ่յΛ༻͍࣮ͨ‫͔ݧ‬ΒͷΈͰ

2116͋ͬͨɻ΋͠ߴ͍ੈ୅ͷϨϓτϯ΁બ୒తʹΧοϓϧ͢ͰͷχϡʔτϦϊৼಈ‫΁Ͳͳڀݚ‬ͷ࣮༻తͳσʔλΛఏΔ৽ཻࢠ͕ଘࡏ͢ΔͳΒ͹‫ٯ‬աఔͰ͋ΔχϡʔτϦϊࢄ‫͢ڙ‬Δɻ

ཚʹ͓͍ͯ΋ϨϓτϯීวੑΛഁΔ‫ݱ‬৅͕‫ͯ͑ݟ‬વΔ΂͖Ͱ͋ΔɻͦΕ͸χϡʔτϦϊ൓Ԡஅ໘ੵ͕ੈ୅ؒͰҟ
ͳΔ͜ͱΛҙຯ͠ɼਤ 1 தͰԣഁઢ͔ΒͣΕΔ͜ͱʹͳΔɻ͔͠͠ɼ‫ࡏݱ‬ͷଌఆਫ਼౓Ͱ͸χϡʔτϦϊࢄཚʹ͓͍ͯϨϓτϯීวੑΛਫ਼ࠪ͢Δ͜ͱ͸೉͍͠ɻ

1.2

Hidden Sector αʔν

LHC ʹ୅ද͞ΕΔΤωϧΪʔϑϩϯςΟΞʹ͓͚Δ৽෺ཧ୳ࡧʹ͓͍ͯ͸ະͩʹஹީ͕‫ݟ‬ΒΕͳ͍தͰɼ΋্ ‫ ه‬Λ ౿ · ͑ ɼஶ ऀ Β ͸ CERN ͷ SPS ͔ Β ͷ͏Ұͭͷํ޲ੑͰ͋ΔΠϯςϯγςΟϑϩϯςΟΞɼཁ

400 GeV ཅࢠϏʔϜΛ༻͍ͯλ΢χϡʔτϦϊੜ੒Λ

͢ΔʹΧοϓϦϯάίϯελϯτͷ‫ۃ‬Ίͯখ͞ͳํ޲ʹ‫͢ڀݚ‬Δ࣮‫ݧ‬ʢDsTauʣͱλ΢χϡʔτϦϊͷେ౷‫ݕܭ‬৽෺ཧͷ୳ࡧྖҬΛ޿͍͛ͯ͘͜ͱ͕ඞཁͰ͋ΔɻSHiPग़Λߦ͏࣮‫ݧ‬ʢSHiP χϡʔτϦϊϓϩάϥϜʣΛཱҊ

(Search for Hidden Particle) ࣮‫ݧ‬͸ɼCERN SPS ʹΑͨ͠ɻਤ 1 தʹࣔ͞Ε͍ͯΔ DONuT ࣮‫ʹݧ‬ΑΔλ΢

Δ Beam Dump Facility (BDF) ʹ͓͍ͯɼओʹ charmɾχϡʔτϦϊଌఆͰ͸χϡʔτϦϊੜ੒ʹΑΔ‫ܥ‬౷‫ࠩޡ‬(>50%) ͱখ౷‫ܭ‬ͷ‫ݕ‬ग़਺ (9 ྫ) ʹΑΔ౷‫( ࠩޡܭ‬33%)

beauty ཻࢠͷ่յʹ͓͍ͯੜ੒͞ΕΔ hidden sector
particle ͷՄೳͳ‫ݶ‬Γଟ͘ͷ่յϞʔυΛଊ͑Δ Hid-ͷ྆‫͕ࠩޡ‬ཁҼͱͳΓඇৗʹେ͖ͳෆఆੑ͕͍͍ͭͯ

den Sector (HS) decay spectrometer ͱɼχϡʔτϦϊΔɻΑͬͯߴ͍ਫ਼౓ͷଌఆΛ࣮‫͢ݱ‬Δʹ͸λ΢χϡʔτ͓Αͼ Light Dark Matter (LDM) ͷ෺࣭ͱͷ૬‫༻࡞ޓ‬Ϧϊͷੜ੒ɾ‫ݕ‬ग़ͷ྆ऀͷਫ਼౓޲্͕ඞཁͱͳΔɻਤ 2

Λ௨ͯ͠‫ݕ‬ग़͢ΔͨΊͷ Scattering and Neutrino De-ʹλ΢χϡʔτϦϊଌఆͷͨΊͷ࣮‫ݧ‬ηοτΞοϓͷ֓

tector(SND) ͱͰߏ੒͞ΕΔɻਤ 3 ʹ࣮‫૷ݧ‬ஔͷ֓ཁΛ೦ਤΛࡌͤΔɻλ΢χϡʔτϦϊΛਓ޻తʹੜ੒͢Δࣔ͢ɻʹ͸ɼߴΤωϧΪʔཅࢠΛඪతʹ౰ͯɼDs தؒࢠ (cs̄·ͨ͸ c̄s) Λੜ੒͠ɼ͔ͦ͜Βͷ࿈࠯่յ Ds → τ ντ ɼ

τ → ντ X Λར༻͢Δɻ͜ͷํ๏͸ DONuT ࣮‫Ͱݧ‬΋࠾༻͞Εͨɻੜ੒ʹΑΔओͳෆఆੑ͸ Ds ͷඍ෼ੜ੒அ໘

ੵͰ͋Δɻಛʹཅࢠ൓Ԡʹ͓͍ͯ Ds ͷॎํ޲ӡಈྔґଘੑʹ͍ͭͯͷଌఆ͕͜Ε·Ͱʹใࠂ͞Ε͍ͯͳ͍ɻඍ
෼ੜ੒அ໘ੵ͸λ΢χϡʔτϦϊ‫ݕ‬ग़‫ث‬Λԣ੾ΔχϡʔτϦϊ਺ʢϑϥοΫεʣΛܾఆ͢ΔͨΊɼਫ਼౓Α͘஌Δ
ඞཁ͕͋Δɻ͜ΕΛ DsTau ࣮‫୲͕ݧ‬౰͠ɼλ΢χϡʔτϦϊଌఆͷ‫ܥ‬౷‫ࠩޡ‬Λ 10%ఔ౓ʹ·Ͱ཈͑Δɻଞํ
ͰɼSHiP ࣮‫ݧ‬͸໿ 10,000 ࣄ৅ͷλ΢χϡʔτϦϊ൓ԠΛ஝ੵ͠ɼ౷‫ࠩޡܭ‬Λ 2%ʹ·Ͱখ͘͢͞Δ‫ܭ‬ըͰ͋Δɻ
charged particle sweeping,�� production target neutron absorption
�� acceptance ~ 5%
400 GeV (e.g. tungsten)
proton�� detector
�� beam�� production
��proton

�

≃5mm

��
��

�

�

��

�� detection

��

�

≃5mm

�

ਤ 3: SHiP ࣮‫૷ݧ‬ஔ: ࠨ͔ΒλʔήοτͱͦΕΛғΉ࣓Խ͞ΕͨϋυϩϯΞϒιʔόʔɼϚάωοτͰߏ੒͞ΕͨϛϡʔΦϯΛ sweep ͢Δҝͷ Active Muon shieldɼதԝลΓʹ Scattering and Neutrino Detectorɼͦͷ‫ʹํޙ‬

sweep ͨ͠ϛϡʔΦϯΛආ͚ΔͨΊͷϐϥϛου‫ܕ‬ͷਅۭͷ decay volumeɼͦͷ‫ ʹํޙ‬HS decay spectrometerΛ࣋ͭશ௕໿ 120 m ͷ࣮‫૷ݧ‬ஔͱͳΔɻ‫ Ͱ఺࣌ݱ‬SHiP Ҏ֎ʹ΋ෳ਺ͷ௕ण໋ཻࢠͷ୳ࡧΛ໨తͱ࣮ͨ͠‫ܭݧ‬ը͕ٞ࿦͞Ε͍ͯΔ͕ɼSHiP ࣮‫ݧ‬͸charmɾbeauty ཻࢠͷ࣭ྔҎԼͷྖҬʹ͓͍ͯඇৗʹେ͖ͳ୳ࡧྖҬΛ࣋ͭɻಛʹ Hidden particle ͷ model

independent ͳαʔνΛߦ͏ͨΊʹɼՄೳͳ‫ݶ‬Γଟ͘ͷ่յϞʔυΛ particle ID ΋‫ؚ‬Ίͯ‫ݕ‬ग़͢ΔͨΊͷ૷ஔΛ༗͢Δɻଟ͘ͷ่յϞʔυΛଊ͑ΔࣄʹΑΓɼHeavy

Neutral Lepton (HNL) Λ͸͡Ίɼdark photonɼdark
scalarɼaxion-like particles ౳ʹରͯ͠‫౓ײ‬Λ࣋ͭɻਤਤ 2: λ΢χϡʔτϦϊଌఆͷͨΊͷ࣮‫ݧ‬ϨΠΞ΢τɻ2 ͭͷ࣮‫ݧ‬Λ‫ͯܦ‬λ΢χϡʔτϦϊ൓Ԡஅ໘ੵΛ 10%ҎԼͷਫ਼౓Ͱ஌Δ͜ͱʹ͸ඇৗʹՁ஋͕͋Δͱߟ͑Δɻ·ͨ‫ૅج‬త‫ڵ‬ຯҎ্ʹɼ͜͜ͰಘΒΕΔ 10–150 GeV ྖҬͰͷχϡʔτϦϊ൓Ԡஅ໘ੵ͸ Super-K ΍ Hyper-K

4 ʹ HNL ʹର͢Δ‫౓ײ‬Λࣔ͢ɻଞͷϞʔυʹؔͯ͠͸ผࢴ [3, 4] Λࢀর͞Ε͍ͨɻ

3117

͸൓Ԡͷ௒લํɼ‫ऀޙ‬͸ඪత‫֩ࢠݪ‬ͷ੩ࢭ‫Ͱܥ‬ͷνϟʔϜཻࢠͱͳͬͯ‫؍‬ଌ͞ΕΔɻ‫ס֩ࢠݪ‬൘τϥοΧʔͷߴҐஔ෼ղͱ޿ΞΫηϓλϯεʹΑΓ྆ऀͷੜ੒཰ͷଌఆΛߟ͍͑ͯΔɻ

2

DsTauɾSHiP ࣮‫ݧ‬ͷ‫ݱ‬ঢ়ஶ ऀ Β ͸ ɼDsTau/NA65 ࣮ ‫ ݧ‬ͷ Spokespersonɼ

Deputy SpokespersonɼPhysics Coordinator ͱͯ͠ຊ‫ڀݚ‬Λࠃࡍ‫ڞ‬ಉ‫( ڀݚ‬5ϲࠃ 9 ‫ͯʹ )ؔػڀݚ‬ਪਐ͍ͯ͠
ਤ 4: SHiP ͷ Heavy Neutral Lepton ʹର͢Δ‫౓ײ‬Δɻ͜Ε·Ͱͷ‫ܦ‬Ңͱͯ͠͸ɼCERN-SPS ͷ 400 GeVཅࢠϏʔϜΛ༻͍ͯ DsTau ࣮‫ݧ‬Λߦ͏͜ͱΛཱҊ͠ɼ

1.3

Charm ProductionɼIntrinsic CharmɼPrompt Neutrino Study

2016 ೥ 2 ݄ʹ CERN SPS/PS ࣮‫ݧ‬৹ࠪҕһձ (SPSC)
ʹ letter of intent Λఏग़ͨ͠ [7]ɻ2016/2017 ೥ʹϏʔϜςετΛ࣮ࢪ͠ɼ࣮‫ݧ‬ϓϩϙʔβϧ [8] Λࣥචͯ͠νϟʔϜཻࢠ͸ɼຊ‫ڀݚ‬ͷΤωϧΪʔྖҬͰ͸ɼϋυ

2017 ೥ 8 ݄ʹ SPSC ʹఏग़ͨ͠ɻ2018 ೥ 1 ݄ͷ SPSC

ϩϯ൓Ԡͷࡍʹ 1000 ൓ԠʹҰରఔ౓ͷׂ߹Ͱੜ੒͞ΕʹΑΔ৹ࠪʹͯɼ2018 ೥ύΠϩοτϥϯͷঝೝͱ 2021Δɻ‫ݻ‬ఆඪతͷ৔߹ɼલํํ޲ʹ 2 ཻ࣍ࢠ͕ूத͢Δ೥ͷϏʔϜλΠϜ֬อͷਪ঑Λड͚ɼ2018 ೥ 8 ݄ʹࠓͨΊɼ௒લํํ޲ʹ͓͍ͯ͸ඈ੻෼཭ͷࠔ೉͔͞Β୳‫ޙ‬ͷ෺ཧϥϯͷ 1/10 ʹ૬౰͢Δ‫ݕ‬ग़‫ث‬Λ༻͍ͯύΠࡧ͠ਚ͘͞Εͯ͸͍ͳ͍ɻ͜ͷྖҬΛ‫͢ڀݚ‬Δ͜ͱͰ͍ϩοτϥϯΛ࣮ࢪͨ͠ɻղੳঢ়‫گ‬Λ SPSC ʹใࠂ͠ɼ͔ͭ͘ͷ‫ڵ‬ຯਂ͍෺ཧʹഭΔ͜ͱ͕Ͱ͖Δɻྫ͑͹ɼ֩

2019 ೥ 6 ݄ɼCERN Research Board ʹΑΓ DsTau ࣮ࢠ͸ՁΫΥʔΫ 3 ‫ͱݸ‬άϧʔΦϯʢϋυϩϯ൓Ԡͷࡍ‫ݧ‬͸ NA65 ͱͯ͠ਖ਼ࣜঝೝ͞Εɼ2021/2022 ೥ͷ෺ཧ͸ւΫΥʔΫͱͯ͠‫͑ݟ‬ΔʣͰͰ͖͍ͯΔɻՁΫΥʔΫϥϯ͕ೝΊΒΕͨɻ‫ࡏݱ‬͸ɼύΠϩοτϥϯͷղੳ͓͸ u ·ͨ͸̳ΫΥʔΫͰ͋Δɻͱ͜Ζ͕νϟʔϜΫΥʔΑͼ෺ཧϥϯͷ४උʹऔΓ૊ΜͰ͍Δɻ

Ϋ͕֩ࢠ಺ͰՁΫΥʔΫͷΑ͏ʹৼ෣͍ͬͯΔՄೳੑχϡʔτϦϊ͸Ұ࣍Ӊ஦ઢʢओʹཅࢠʣ͕େ‫ۭͰ্ۭؾ‬SHiP ࣮‫ܭݧ‬ը͸ 2015 ೥ 4 ݄ʹ SPSC ʹ Technical
Proposal[9] Λఏग़͠ɼಉ࣌ʹ SHiP ʹ͓͍ͯ‫ظ‬଴Ͱ͖Δ෺ཧΛ·ͱΊͨ review article [3] ΋߹Θͤͯఏग़ͨ͠ɻ

‫ؾ‬෼ࢠͷ‫ͱ֩ࢠݪ‬িಥɾϋυϩϯ൓Ԡͷੜ੒ 2 ཻ࣍ࢠ͕2015 ೥ͷϓϩϙʔβϧ࣌఺Ͱ͸໿ 170 ໊ɼ45 ‫ؔػ‬ɼ14ϱϨϓτχοΫ่յ͢Δࡍʹ์ग़͞ΕΔɻΤωϧΪʔͷ௿ࠃͰ͕͋ͬͨɼ2019 ೥຤ʹ͸໿ 250 ໊ɼ57 ‫ؔػ‬ɼ18ϱ͍େ‫ؾ‬χϡʔτϦϊͷ‫ݯ‬͸ओʹ π தؒࢠͦͯ͠ K தؒࠃʹ·Ͱ૿͍͑ͯΔɻ͜ͷϓϩϙʔβϧ͸ SPSC ʹΑΔ

ࢠͰ͋ΔɻΤωϧΪʔ͕ߴ͘ͳΔͱ π ΍ K தؒࢠ͸่
յ͢Δલʹۭ‫ؾ‬ͷ‫ʹ֩ࢠݪ‬িಥ͢ΔͨΊ୹ण໋ͷνϟʔϨϏϡʔΛड͚ɼ2016 ೥ʹ͸ SPSC ͔Β 3 ೥ؒͷ Comprehensive Design Study (CDS) ‫ؒظ‬Λ༩͑ΒΕɼՃ͑Ϝཻࢠ͕ߴΤωϧΪʔχϡʔτϦϊͷ‫ͳʹݯ‬ΔɻߴΤωͯ CERN ͕૊৫ͨ͠ Physics Beyond Collider forumϧΪʔͷେ‫ؾ‬χϡʔτϦϊ੒෼ͷཧղ͸Ӊ஦χϡʔτϦ(PBC) ͷ R&D ϓϩδΣΫτʹ BDF ͱͱ΋ʹਖ਼ࣜʹՃϊͱͷหผͷࡍʹॏཁͰ͋ΔɻಛʹҰ࣍Ӊ஦ઢʹରͯ͑͠ΒΕ্ͨʹɼEuropean Particle Physics Strategy Update (EPPSU) ʹϓϩϙʔβϧΛग़͢Α͏ʹ PBC ʹਪ঑ʢintrinsic charmʣ͕ٞ࿦͞Ε͍ͯΔ [5, 6]ɻ·ͨɼେ‫ؾ‬௒લํͷνϟʔϜੜ੒ͷཧղ͕ඞཁͰ͋Δɻ

DsTau ࣮‫Ͱݧ‬͸ߴΤωϧΪʔཅࢠͱλϯάεςϯඪత͞ΕͨɻComprehensive Design Study ͷ݁Ռ͸ EPPSUͷϋυϩϯ൓Ԡ໿ 2×10 ࣄ৅Λ‫ס֩ࢠݪ‬൘τϥοΧʔͰ΁ͷϓϩϙʔβϧͱͯ͠ SHiP ࣮‫[ ݧ‬10] ͱ BDF[11] ‫ʹڞ‬‫ه‬࿥͢ΔɻαϒϛΫϩϯͷҐஔ෼ղͱ޿͍֯౓ΞΫηϓ2019 ೥ 1 ݄ʹఏग़ͨ͠ɻSHiP/BDF ซͤͯ 2019 ೥ 5 ݄λϯεΛੜ͔͠ɼ௒લํ͔ΒϏʔϜ‫Ͱ·ํޙ‬ϋυϩϯ൓ͷάϥφμͰͷ Open EPPSU Symposium ʹͯूதతʹ8ԠͰੜͨ͡νϟʔϜཻࢠΛ୳ࡧɾղੳ͢Δɻ໿ 2×10 ࣄٞ࿦͞ΕඇৗʹϙδςΟϒʹड͚ೖΕΒΕͨɻͦͯ͠ɼ

৅ͷϋυϩϯ൓Ԡ͔Β਺ 10 ສࣄ৅ͷνϟʔϜཻࢠੜ੒ࣄ৅Λ‫ࠐݟ‬ΜͰ͓ΓɼνϟʔϜཻࢠੜ੒அ໘ੵ΍νϟʔ

2019 ೥ 12 ݄ʹ Comprehensive Design Study (CDS)
report[12] Λ SPSC ʹఏग़ͨ͠ɻ2020 ೥ʹ Technical De-ϜରͷνϟʔϜཻࢠؒ૬ؔͷղੳΛߦ͍ɼ্‫ه‬ͷ௒લํsign Report (TDR) ΁ͷঝೝ͕ग़Ε͹ɼ2023 ೥·ͰʹͰͷνϟʔϜཻࢠੜ੒΋‫͢ڀݚ‬Δɻ·ͨɼٞ࿦ʹͳͬͯ

TDR Λ४උ͢ΔӡͼͱͳΔɻ͜ΕʹΑΓ‫ݐ‬ઃ΁ͷΞϓ8

͍Δ intrinsic charm ঢ়ଶ͕ଘࡏ͢ΔͷͰ͋Ε͹ϏʔϜϧʔόϧ͕ग़Ε͹ 5 ೥͔Β 6 ೥ͷ४උ‫ؒظ‬Λ‫ͯܦ‬ɼૣ͚ཅࢠͷதͷ charm ՁΫΥʔΫ༷νϟʔϜͱඪత֩ࢠͷத

Ε͹ 2028 ೥ʹσʔλςΠΩϯά͕࢝·Δ‫ࠐݟ‬ΈͰ͋ΔɻͷՁΫΥʔΫ༷νϟʔϜ͕ߟ͑ΒΕΔɻ࣮‫ݧ‬తʹ͸લऀ

4
118

3

DsTau/NA65 ࣮‫ݧ‬

3.1

‫ݕ‬ग़‫ث‬DsTau/NA65 ࣮‫ݧ‬͸ɼ400 GeV ཅࢠϏʔϜͱλϯάεςϯඪతͱͷ൓Ԡͷࡍͷλ΢χϡʔτϦϊੜ੒Λଌఆ͢Δɻ400 GeV ཅࢠ͕λϯάεςϯ‫ͱ֩ࢠݪ‬൓Ԡ͢Δͱ

10 ͔Β 20 ຊͷՙిཻࢠɼಉఔ౓ͷதੑཻࢠ͕ੜ੒͞ΕΔɻ͜ͷ͏ͪλ΢χϡʔτϦϊͷ‫ͳʹݯ‬Δͷ͸νϟʔϜதؒࢠͷҰछͷ Ds தؒࢠͰ͋ΔɻDs− → τ − ν τ ͦͯ͠

τ − → Xντ ͷ่յ࿈࠯ʹΑΓλ΢χϡʔτϦϊ͕ੜ੒͞ΕΔɻDs தؒࢠͷੜ੒཰Λ Ds தؒࢠͷΤωϧΪʔͷؔ਺ͱͯ͠ଌఆ͢Ε͹λ΢χϡʔτϦϊϑϥοΫ෼෍ਤ 5: DsTau/NA65 ࣮‫ݧ‬ͷ‫ݕ‬ग़‫ߏث‬଄Λਫ਼౓Α͘‫͖Ͱࢉܭ‬Δɻ

DsTau/NA65 ࣮‫Ͱݧ‬͸ɼ͜ͷ่յ࿈࠯Λಉఆ͠ɼDs
தؒࢠͷΤωϧΪʔΛଌఆ͢ΔͨΊʹ‫ס֩ࢠݪ‬൘Λ༻
͍ΔɻDs− → τ − ν τ ͦͯ͠ τ − → Xντ ͷ่յ࿈࠯Λ‫ݕ‬ग़‫ݟͰث‬Δͱɼୈ 1 ่յͰඈ੻͕ંΕ‫͕ۂ‬ΓʢΩϯΫͱ‫Ϳݺ‬ʣɼୈ 2 ่յͰ·ͨඈ੻͕ંΕ‫͕ͨͬۂ‬Α͏ʹ‫͑ݟ‬ΔɻͦΕͧΕͷ่յ·Ͱͷ Ds தؒࢠɼτ ཻࢠ͸਺mm ͷඈఔͰ͋Δɻσʔλʹ͓͍ͯɼҰ࣍൓Ԡ఺͔Β਺mm ͷதʹંΕ‫͕ۂ‬Γ͕ 2 ճ͋Δ΋ͷΛ୳ࡧ͢Δɻಛʹ
Ds− → τ − ν τ ͷ่յͰ͸ Ds ͱ τ ͷ࣭ྔ͕ࠩখ͍ͨ͞Ί֯౓ࠩ͸ฏ‫ ۉ‬7mrad ͱখ͍͞ɻ਺ mm ͷ‫ Ͱ཭ڑ‬mradఔ౓ͷ֯౓ࠩΛ‫ݕ‬ग़ɾଌఆ͢ΔͨΊʹɼφϊਫ਼౓ͷҐஔਫ਼౓Λ࣋ͭ‫ס֩ࢠݪ‬൘Λਤ 5 ͷΑ͏ʹ഑ஔ͠ɼλϯάεςϯ൓Ԡͷத͔Β࿈ଓΩϯΫࣄ৅ΛબผɾৄࡉղੳΛߦ
͏ɻDs தؒࢠͷΤωϧΪʔ͸่յ࿈࠯ͷ Ds ཻࢠͷඈ
ఔɼDs → τ ่յ֯ɼτ ͷඈఔɼτ → X Ͱͷ่յ֯ͷ

4 ม਺Λ༻͍ͯਪఆ͢ΔɻDs ͷΤωϧΪʔ͕ߴ͍ʢ௿͍ʣ΄Ͳඈఔ͸௕͘ʢ୹͘ʣ่յ֯͸খ͘͞ʢେ͖͘ʣ
ͳΔಛ௃Λར༻͢Δɻ‫ݕ‬ग़‫ث‬ͷҐஔ֯౓ਫ਼౓Λ‫ؚ‬Ίͨγ
ϛϡϨʔγϣϯσʔλʹΑΔ 4 ม਺ͷ‫ػ‬ցֶशʹΑΓɼ
໿ 20%ͷΤωϧΪʔਪఆਫ਼౓Λ‫ࠐݟ‬ΜͰ͍Δ [1]ɻϏ ʔ Ϝ ཅ ࢠ Λ ‫ ס ֩ ࢠ ݪ‬൘ τ ϥοΧ ʔ ͷ શ ໘ ੵ
ʢ12.5 cm×10 cmʣʹ‫ۉ‬౳ͷີ౓Ͱরࣹ͢ΔͨΊɼ‫ࢠݪ‬֩‫ס‬൘τϥοΧʔ͸ x-y εςʔδʹ౥ࡌ͠ϏʔϜεϐϧਤ 6: DsTau/NA65 ࣮‫ݧ‬ͷরࣹηοτΞοϓ
ςοϓΛ౿Ή͜ͱͱɼେ౷‫ܭ‬ཅࢠ൓Ԡղੳͷཱ֬ͱಘΒΕͨ݁ՌΛա‫ڈ‬ͷ DONuT ࣮‫ݧ‬ͷέʔεʹదԠ͢Δ͜ͱʹΑΓ 2021 ೥Λ଴ͨͣͯ͠λ΢χϡʔτϦϊ൓Ԡஅ໘ੵͷਫ਼౓Λ্͛Δ͜ͱͰ͋Δɻ2018 ೥य़ΑΓ 55 m2 ͷ‫ס֩ࢠݪ‬൘/ΤϚϧγϣϯϑΟϧϜΛ໊‫ݹ‬԰େͱϕϧϯେʹͯ‫ ܭ‬3ϱ݄Λ͔͚ͯੜ࢈ͨ͠ɻ8 ݄ʹ͸ CERN ʹͯ‫ݕ‬ग़‫ث‬Ϟδϡʔϧͷ૊ΈཱͯΛߦ͍ɼSPS-H2 ϏʔϜϥΠϯʹͯɼ3.5×108 ͷ 400 GeV ཅࢠΛԆ΂ 30 Ϟδϡʔϧʹরࣹͨ͠ɻ͜ͷরࣹΩϟϯϖʔϯʹ͸ 4 ͔ࠃ 11 ໊ͷ‫ࢀ͕ऀڀݚ‬Ճͨ͠ (ਤ 7)ɻ
ΤϚϧγϣϯϑΟϧϜͷಡΈऔΓ͸ɼ໊‫ݹ‬԰େֶͰՔ

ຖʹ x ํ޲ʹಈ͔͢ʢਤ 6ʣɻ࣮ࡍʹ͸ɼ໿ 4 ඵؒͷεϐϧ಺ͰϏʔϜ‫͕౓ڧ‬େ͖͘;Βͭ͘ɻ͜ΕΛϏʔϜΧ΢ϯλʔͱಉ‫͢ظ‬Δ͜ͱͰεϐϧͷؒͷҠಈ଎౓ΛμΠφϛοΫʹௐ੔͢Δ͜ͱͰরࣹີ౓༳Β͗Λ 10%ҎԼʹ͍ͯ͠Δɻ໿ 2×108 ൓ԠΛ஝ੵ͢ΔͨΊ໿ 400Ϟδϡʔϧͷ‫ס֩ࢠݪ‬൘τϥοΧʔʹཅࢠϏʔϜΛর
ࣹ͢Δɻ

3.2

2018 ೥ύΠϩοτϥϯ

ஶऀΒ͸ 2018 ೥ʹશମͷ 1/10 εέʔϧͷύΠϩο
τϥϯΛߦͬͨɻͦͷ໨త͸࣮‫ݧ‬ͷେ‫ܕ‬Խʹ޲͚ͯͷεਤ 7: DsTau ύΠϩοτϥϯνʔϜͷҰ෦ɼSPS-H2 ϏʔϜϥΠϯʹͯɻ

5119ͷ่յΛ‫ؚ‬Ήީิ 86 ࣄ৅Λ‫ݕ‬ग़ͨ͠ɻ‫ݕ‬ग़਺ʹ͍ͭͯ͸‫ظ‬଴஋ͱͷໃ६͸ͳ͍͜ͱΛ֬ೝ͠ɼ֯౓෼෍ͳͲͷৄࡉղੳΛߦ͍ͬͯΔɻ‫ݕ‬ग़ͨ͠ࣄ৅ͷҰྫΛਤ 9 ʹࣔ͢ɻ͞ΒʹɼͦΕΒͷࣄ৅ʹ͓͚ΔՙిνϟʔϜ/λ΢ީิʹ͍ͭͯɼඍখͳંΕ‫͕ۂ‬Γͷ༗ແΛௐ΂Δ͜ͱʹΑΓɼDs தؒࢠͷλ΢ཻࢠ΁ͷ่յΛ୳ࡧ͢Δɻ਺
mrad ͱ͍͏ඍখͳંΕ‫͕ۂ‬ΓΛಛ௃ͱ͢Δ Ds தؒࢠͷ่յΛ‫ݕ‬ग़͢Δʹ͸φϊਫ਼౓Ͱͷඈ੻ͷଌఆ͕ඞཁͰ
͋ΓɼͦͷͨΊͷਫ਼ີଌఆγεςϜΛϕϧϯେֶʹͯ։ൃ͍ͯ͠Δɻ
ਤ 8: ֤ϑΟϧϜͰͷඈ੻ͷ‫ݕ‬ग़ޮ཰ɻ൪߸͕খ͍͞ଆ
্͕ྲྀɻ
kink

ಇதͷ௒ߴ଎ඈ੻ಡΈऔΓ૷ஔ HTS Ͱ਱ߦ͍ͯ͠ΔɻHTS ͷඈ੻ 1 ຊ͋ͨΓͷ֯౓ਫ਼౓͸ 2.5 mrad Ͱ͋Γɼλϯάεςϯதͷ൓Ԡ΍ɼτ ͷ่յࣄ৅Λಉఆ͢Δʹ͸

neutral decayे෼ͳਫ਼౓Ͱ͋Δɻ

primary vertex

2018 ೥ύΠϩοτϥϯͷ 30 ϞδϡʔϧͷಡΈऔΓ͸

400 GeV proton

2019 ೥຤࣌఺Ͱ໿ 90%Λ‫ͨྃ͠׬‬ɻಡΈऔͬͨඈ੻ू

500 μmஂͷҐஔͱ֯౓ͷ৘ใ͔ΒɼϑΟϧϜ͝ͱͷඈ੻Λ઀ଓɾ࠶ߏ੒͠ɼϑΟϧϜ 1 ຕຖͷඈ੻ͷ༗ແΛௐࠪ͢Δ͜ͱ
ͰɼϑΟϧϜͱಡΈऔΓͷධՁΛߦͬͨɻඈ੻࠶ߏ੒ͱ
ධՁ͕‫ ͨྃ͠׬‬13 Ϟδϡʔϧ෼ͷɼ֤ϑΟϧϜ͝ͱͷඈ੻ͷ‫ݕ‬ग़ޮ཰ͷ݁ՌΛਤ 8 ʹࣔ͢ɻ‫ݕ‬ग़ޮ཰͸ɼධՁਤ 9: ՙి 1-prong τϙϩδʔ (kink, νϟʔϜ/λ΢ީิ) ͱதੑ 2-prong τϙϩδʔΛ่࣋ͭյީิ (ࣼΊ͔Β‫ͨݟ‬ඳ૾) [1]ɻ͍ͨ͠ϑΟϧϜͷ্ྲྀ 1 ຕͱԼྲྀ 2 ຕͰ઀ଓͰ͖ͨඈ੻
ʹର͠ɼͦͷϑΟϧϜͰඈ੻͕֬ೝ͞Εׂͨ߹Ͱ͋Δɻ

tanθ <0.1 ͷ֯౓ۭؒʹ͓͍ͯɼ2 ཻ࣍ࢠʹΑΓඈ੻ີ౓͕ߴ͘ͳΓඈ੻࠶ߏ੒ͷ৚͕݅ѱ͘ͳΔԼྲྀϑΟϧϜͰ΋ɼ95%Ҏ্ͷ‫ݕ‬ग़ޮ཰Λୡͨ͠ɻϏʔϜԼྲྀϑΟϧϜʹ͓͚Δඈ੻ີ౓͸ 5×105 /cm2 ͱɼHTS ͕͜Ε·Ͱର৅ͱ͖ͯͨ͠ඈ੻ີ౓ΑΓ΋ 1 ܻଟ͍͕ɼ࣮‫ݧ‬਱ߦʹे෼ͳ‫ݕ‬ग़ޮ཰Λୡ੒Ͱ͖ͨɻҰ෦ͷϑΟϧϜͰ‫ݕ‬ग़ޮ཰ͷ௿Լ͕‫ݟ‬ΒΕΔ͕ɼ‫ݪ‬Ҽ͸ಡΈऔΓͰ͸ͳ͘ϑΟϧϜͷ඼࣭ʹґΔ΋ͷͰ͋Γɼࠓ‫ޙ‬ͷ෺ཧϥϯͰྑ࣭ͳϑΟϧϜΛ੡଄ɾϋϯυϦϯά͢Δ͜ͱͰվળՄೳ
Ͱ͋Δɻ
ஶऀΒ͸ɼ͜Ε·ͰͷχϡʔτϦϊ࣮‫ ݧ‬CHORUSɾ

DONuTɾOPERA ʹ͓͍ͯ୹ण໋ཻࢠͷ่յ୳ࡧΛओಋͨ͠‫ݧܦ‬Λੜ͔͠ɼཅࢠ൓ԠΛ࠶ߏ੒ͯ͠νϟʔϜ/λ΢ཻࢠͷ่յτϙϩδʔΛબͼग़ࣗ͢ಈղੳεΩʔϜͷߏஙʹऔΓ૊ΜͰ͖ͨɻखॱͱͯ͠͸ɼෳ਺ຕͷΤϚϧγϣϯϑΟϧϜΛ௨ͯ͠࠶ߏ੒͞Εͨඈ੻Λ༻͍ͯཅࢠ൓Ԡ఺Λ૊ΈɼͦͷதͰνϟʔϜ/λ΢ཻࢠͷ่յΛ‫ؚ‬Ήࣄ৅Λ୳ࡧ͢Δɻ͜ͷ୳ࡧͰ͸ɼՙిཻࢠͷ่յީิͱɼͦͷϖΞͱͳΔՙి/தੑνϟʔϜཻࢠͷ่յީิΛ‫ؚ‬Ήࣄ৅Λબͼग़͢ɻৄࡉͳ৚݅ʹ͍ͭͯ͸ [13] Ͱड़΂͍ͯΔɻ͜Ε·Ͱʹαϒαϯϓϧͱͯ͠ɼ400 GeVཅࢠ൓Ԡ 76151 ࣄ৅ͷղੳΛߦ͍ɼνϟʔϜ/λ΢ཻࢠ

3.3෺ཧϥϯʹ޲͚ͯ

2021-2022 ೥ͷ෺ཧϥϯͰ͸ɼཅࢠ൓Ԡ 2×108 ࣄ৅ʢैདྷͷΤϚϧγϣϯ࣮‫ʹݧ‬ରͯ͠ 2 ܻҎ্ଟ͍ղੳࣄ
৅਺ʣͷղੳΛ਱ߦ͢Δɻཅࢠ൓ԠͰੜ੒͞ΕΔ Ds தؒࢠͷλ΢ཻࢠ΁ͷ่յ͕໿ 1000 ࣄ৅‫ݕ‬ग़͞ΕΔͱ‫ݟ‬ੵ΋͍ͬͯΔɻDs தؒࢠ͸୹ण໋Ͱ่յ͢Δ͜ͱ͔ΒͦͷӡಈྔΛ௚઀ଌఆ͢Δ͜ͱ͸೉͍ͨ͠Ίɼ่յ֯ͳ
Ͳͷ‫ز‬Կֶత৘ใΛ૊Έ߹Θͤͯਪఆ͢Δख๏Λߏங͖ͯͨ͠ [1]ɻͦͷख๏Λ༻͍ͯɼ400 GeV ཅࢠ൓Ԡʹ͓
͚Δ Ds தؒࢠͷඍ෼ੜ੒அ໘ੵΛଌఆ͢Δɻ͜ͷσʔ
λ͸ SHiP ͳͲͷকདྷ‫ܭ‬ըʹ͓͚Δλ΢χϡʔτϦϊϑϥοΫεͷ‫ੵݟ‬΋Γʹ௚઀ߩ‫͢ݙ‬ΔͩΖ͏ɻDs தؒࢠͷ
2ඍ෼ੜ੒அ໘ੵΛ d2 σ/dxF /dp2T ∝ (1− | xF |)n · e−b·pTͱ͍͏‫ݱ‬৅࿦తͳࣜͰϑΟοτ͢Δͱͯ͠ɼσʔλ͔Βύϥϝʔλ n ͓Αͼ b Λਪఆ͢Δ͜ͱ͕Ͱ͖Δɻλ΢χϡʔτϦϊ‫ݕ‬ग़ʹ͓͍ͯϑϥοΫε͸ύϥϝʔλ n ʹେ͖͘ґଘ͢Δ͕ɼDs தؒࢠʹର͢Δύϥϝʔλ n ͷ஋͸ཅࢠϏʔϜΛ༻͍ͨ‫ݻ‬ఆඪత࣮‫Ͱݧ‬͸ଌఆ͞Ε͍ͯͳ͍ɻਤ 10 ͸ɼDs தؒࢠͷλ΢ཻࢠ΁ͷ่յࣄ৅ͷ‫ݕ‬ग़਺ͱͦͷ৔߹ʹ‫ظ‬଴͞ΕΔύϥϝʔλ n ͷਫ਼౓Λ͍ࣔͯ͠Δɻ͜ͷਤ͔ΒɼDs தؒࢠͷλ΢ཻࢠ΁ͷ่յΛ໿ 1000 ࣄ৅Λ༻͍Δ͜ͱʹΑΓɼλ΢χϡʔτϦ6120

ϊϏʔϜੜ੒ͷෆఆੑΛ‫ࡏݱ‬ͷ 50%૬౰͔Β 10%ҎԼʹ཈͑Δ͜ͱ͕Ͱ͖Δɻ͜ͷσʔλΛ΋ͱʹɼকདྷతʹλ΢χϡʔτϦϊ൓Ԡʹ͓͚Δ৽෺ཧͷޮՌΛ୳ࡧ͢Δ
͜ͱΛՄೳʹ͍ͨ͠ɻਤ 10: Ds தؒࢠͷλ΢ཻࢠ΁ͷ่յࣄ৅ͷ‫ݕ‬ग़਺ͱɼͦͷ৔߹ʹ‫ظ‬଴͞ΕΔύϥϝʔλ n ͷਫ਼౓ʢδnʣͷؔ܎ [1]ɻӈଆͷ y ࣠͸ɼλ΢χϡʔτϦϊϑϥοΫεͷ
ෆఆੑ΁ͷରԠΛ͍ࣔͯ͠Δɻn = 5.8 ͷ৔߹ʹରͯ͠‫ࢉܭ‬Λߦͬͨɻ

ਤ 11: BDF ͷ‫ݐ‬ઃ༧ఆ৔ॴ: CERN North Area
Δલํ෦෼͸νλϯɾδϧίχ΢ϜΛࠞͥͨϞϦϒσϯ
߹ۚ (TZM) Λ࢖͍ɼԼྲྀଆʹ͸λϯάεςϯΛ༻͍Δɻ

BDF ʹ͸ϏʔϜΤΫετϥΫγϣϯɼτϥϯεϙʔτɼλʔήοτɼαʔϏεϏϧσΟϯάɼ࣮‫ݧ‬ϗʔϧɼ࣮‫ݧ‬ϗʔϧ‫ํޙ‬ͷϛϡʔΦϯγʔϧυ΋‫·ؚ‬ΕΔɻਤ 12ʹ࣮‫ݧ‬ϗʔϧΛ‫ؚ‬Ίͨ BDF ͷࢪઃΛࣔ͢ɻ

SHiP ‫ܭ‬ըʹ͓͚Δ ντ ଌఆ

4SHiP ࣮‫ݧ‬Λߦ͏ϏʔϜμϯϓ (BDF) ͸࠷΋‫ͳྗڧ‬λ΢χϡʔτϦϊ‫͋Ͱݯ‬Δɻ໊‫ݹ‬԰େֶɾѪ஌‫ڭ‬ҭେֶɾਆ‫ށ‬େֶɾ೔ຊେֶɾ౦๜େֶͷ೔ຊάϧʔϓ͸χϡʔτϦϊৼಈʹΑΔλ΢χϡʔτϦϊͷ appearance Λ࣮ূͨ͠

OPERA ࣮‫[ ݧ‬14] Λ਱ߦͨ͠άϧʔϓͰ͋ΓɼDONuT࣮‫ݧ‬ɼOPERA ࣮‫Ͱݧ‬ഓ͖ͬͯͨ‫ס֩ࢠݪ‬൘ٕज़Λ༻͍ਤ 12: BDF ͷ target complex ͱ࣮‫ݧ‬ϗʔϧͯɼScattering and Neutrino Detector (SND) Ͱͷλ΢χϡʔτϦϊͷஅ໘ੵଌఆ΍ Lepton Universality ͷ‫ݕ‬

SHiP ͷ‫ݕ‬ग़‫ث‬͸ਤ 12 ͷ࣮‫ݧ‬ϗʔϧʹΠϯετʔϧ͞ূ͓Αͼ Light Dark Matter (LDM) ͷ‫ݕ‬ग़ʹ௅ΉɻΕΔɻ࣮‫૷ݧ‬ஔͷશମ૾͸ਤ 3 ʹࣔͨ͠௨ΓͰ͋Δɻ͜͜Ͱ͸ࢴ໘ͷ౎߹΋͋Γɼλ΢χϡʔτϦϊͷ‫ݕ‬ग़Λ୲

4.1

BDF+‫ݕ‬ग़‫ث‬͏ SND ʹ͍ͭͯͷΈৄ͘͠঺հ͢ΔɻSND ͸ OPERA࣮‫ݧ‬ͷ Emulsion Cloud Chamber (ECC) ͱಉ༷ͷ ECC

BDF ͸ɼਤ 11 ʹࣔ͢Α͏ʹ CERN ͷ North Area ʹΛओ‫ݕ‬ग़‫͠ͱث‬ɼϓϩϙʔβϧஈ֊Ͱ͸ OPERA ࣮‫ͱݧ‬৽ͨʹ‫ݐ‬ઃ͢Δ༧ఆͰ͋Δɻ‫ط‬ଘͷ North Area ͷࢪઃಉ༷ͷԖϓϨʔτͱ‫ס֩ࢠݪ‬൘Λੵ૚ͨ͠ ECC Λ‫ݕ‬౼ͱͷ‫ڞ‬ଘΛߟྀͯ͠৽ͨͳεϓϦολʔΛՃ͑Δɻ

͍͕ͯͨ͠ɼฏ໘ੑΛอͭ‫͞ͱ౓ڧ‬Βʹ͸ີ౓Λߟྀ͠

BDF ͸ɼSPS ͷ 400 GeV ཅࢠΛ 1 ඵͷ slow extraction Ͱλʔήοτʹμϯϓ͢Δɻ7.2 ඵͷ SPS αΠΫϧͯλϯάεςϯ߹ۚͷϓϨʔτΛ༻͍ΔɻECC ϞδϡʔλΠϜͰͷฏ‫ۉ‬ϏʔϜύϫʔ͸ 355 kW Ͱ͋Δ͕ɼ1 ඵຕͷλϯάεςϯϓϨʔτΛަ‫ڬʹޓ‬Έ 10X0 ͷް͞Λ

ͷ extraction time ಺Ͱͷύϫʔ͸ 2.65 MW ʹୡ͢Δɻ

΋ͭɻ͜ͷ ECC ͷԼྲྀʹ‫ס֩ࢠݪ‬൘ 3 ຕΛ 15 mm ͷؒຊདྷϏʔϜμϯϓλʔήοτͱͯ͠͸λϯάεςϯͷΑ

ִͰ഑ஔ͠ߏ੒ͨ͠ Compact Emulsion Spectrometer͏ʹߴີ౓ͷ෺࣭͕࠷దͰ͋Δ͕ɼ७λϯάεςϯͷ

(CES) ͱɼ‫ס֩ࢠݪ‬൘தͷχϡʔτϦϊ൓Ԡͱ‫ํޙ‬ͷλʔήοτͰ͸೤๲ுʹΑΔετϨεʹ଱͑ΒΕͳ͍ɻmuon ﬁlter ౳ͱରԠͤ͞ΔͨΊͷ Target Tracker (TT)͜ͷͨΊλʔήοτͱͯ͠͸࠷΋೤ετϨεͷେ͖͘ͳͰ wall Λߏ੒͢ΔɻҰͭͷ wall ʹ͸ 2×2 ͷ ECC ͱϧͷαΠζ͸ 40 cm×40 cm Ͱ 35 ຕͷ‫ס֩ࢠݪ‬൘Ͱ 35

CES Λ࣋ͪɼSND ͸શମͰ 19 wall Ͱߏ੒͞ΕΔɻ૯7121λʔήοτ࣭ྔ͸໿ 8 τϯͰ͋ΔɻτϥοΫͷ஝ੵΛ
཈͑Δҝʹ൒೥ຖʹϑΟϧϜΛަ‫͢׵‬ΔɻCES ͸λ΢χϡʔτϦϊͷՙిΧϨϯτ൓ԠʹΑͬͯੜ੒͞ΕΔλ΢ཻࢠ่͕յ່ཻͨ͠ࢠͷӡಈྔͱిՙΛܾఆ͢Δ͜ͱ
Λ໨తͱ͢Δɻਤ 14: SND: SND ͸ 1.2T ͷμΠϙʔϧϚάωοτͷதʹ഑ஔ͞ΕΔɻද 1: χϡʔτϦϊछผ͝ͱͷՙిΧϨϯτ DIS ൓Ԡ਺ͱฏ‫ۉ‬ΤωϧΪʔ

�E� [GeV]ਤ 13: SND ͷ৔ॴͰ‫ظ‬଴͞ΕΔχϡʔτϦϊͷΤωϧ
Ϊʔ෼෍ʢଟ͍ํ͔Β interacted ͷ νμ ɼνe ɼντ ʣ

Nν e

59

Nνμ

42

ϏʔϜμϯϓͰੜ੒͞ΕΔχϡʔτϦϊϏʔϜ͸ਖ਼൓Nντಉ਺ͷχϡʔτϦϊͱిࢠɼϛϡʔɼλ΢શͯͷछྨΛ‫ؚ‬ΜͰ͓Γɼਖ਼൓۠ผͯ͠ղੳ͢ΔͨΊʹ͸ిՙܾఆ͕

Nν e
Nν μ

52
46

ෆՄܽͰ͋Δɻਤ 13 ʹ֤χϡʔτϦϊछผຖͷΤωϧNν τ

CC DIS
1.1 × 106
2.7 × 106
3.2 × 104
2.6 × 105
6.0 × 10536

2.1 × 10470Ϊʔ෼෍Λࣔ͢ɻχϡʔτϦϊ࣮‫͍͓ͯʹݧ‬ϛϡʔΦϯҎ֎ͷిՙܾఆ͸‫ۃ‬Ίͯ೉͍͕͠ɼ‫ס֩ࢠݪ‬൘ͷαϒϛΫϩϯͷҐஔ෼ղೳΛੜ͔ͯ͠ɼΘ͔ͣ 30 mm ͷ‫཭ڑ‬൓Ԡ਺͸ϛϡʔΦϯͷిՙܾఆ͚ͩʹൺ΂ͯେ෯ʹ޲্

Ͱ 10 GeV ·ͰͷϋυϩϯͷిՙܾఆΛߦ͏ɻ͜ͷͨΊ͍ͯ͠ΔɻλϯάεςϯΛඪతͱ͢Δ SHiP ͷ ECC ʹʹ SND ͸ਤ 14 ʹࣔ͢ 1.2 T ͷμΠϙʔϧϚάωοτ

͓͍ͯ͸ τ → e ่յʹ͓͚ΔిࢠͷిՙΛܾఆ͢Δ͜ͷதʹઃஔ͞ΕΔɻ͜ͷϚάωοτ͸χϡʔτϦϊ൓Ԡͱ͸ి࣓γϟϫʔͷ͍ͤͰ CES Λ΋ͬͯͯ͠΋ࠔ೉ͰղੳͷࡍͷϛϡʔΦϯεϖΫτϩϝʔλͱͯ͠΋‫ػ‬ೳ͋͢Δɻ

Δɻ͜ͷ CES ʹΑΓɼλ΢ཻࢠͷϋυϩχοΫ่յʹରͯ͠΋ిՙܾఆ͕ՄೳʹͳΓɼਖ਼൓λ΢χϡʔτϦϊද 2: ่յϞʔυຖͷਖ਼ɾ൓λ΢χϡʔτϦϊͦΕͧΕΛࣝผͰ͖Δ਺͸ϛϡʔΦϯ͚ͩͰਖ਼൓Λࣝผ͢Δͷʹͷ‫ݕ‬ग़਺‫ظ‬଴஋ൺ΂ͯ 3 ഒҎ্ʹ૿΍͢͜ͱ͕ՄೳͱͳΔɻ

4.2‫ظ‬଴͞ΕΔ੒Ռ

SHiP ࣮‫Ͱݧ‬͸ BDF ʹ 5 ೥ؒͰ 2×1020 PoT Λ༧ఆ͠
͍ͯΔɻ͜ͷ਺ࣈ͸ OPERA ࣮‫ ͍ͨ༻Ͱݧ‬CERN Neu-

Decay Mode

ντ

ντ

τ →μ
τ →h
τ → 3h

1200
4000
1000

1000
3000
700

6200

4700

Total

trino beam to GranSasso (CNGS) ͷ࣮੷ 1.8×1020 PoTͱ΄΅ಉ͡Ͱ͋Γे෼‫࣮ݱ‬తͳ਺ࣈͰ͋Δɻ‫ظ‬଴͞ΕΔ

͜ΕΒͷ 5000 ൓ԠΛ௒͑Δ౷‫ʹ਺ܭ‬ΑΓɼ൓Ԡஅ໘

χϡʔτϦϊ൓Ԡ਺ͱͦͷฏ‫ۉ‬ΤωϧΪʔΛද 1 ʹࣔ͢ɻੵͷଌఆʹ͓͍ͯ΋ɼա‫ڈ‬ͷ DONuT ࣮‫Ͱݧ‬ͷ 9 ൓Ԡɼ͜ͷ൓Ԡ਺ʹ൓Ԡͷ‫ݕ‬ग़ޮ཰ɼిՙࣝผޮ཰Λ‫צ‬Ҋ͠

OPERA ࣮‫Ͱݧ‬ͷ 10 ൓Ԡͱ͸ܻҧ͍ͷ౷‫ܭ‬ਫ਼౓ΛಘΒͯ‫ظ‬଴͞ΕΔਖ਼ɾ൓λ΢χϡʔτϦϊ൓Ԡ਺͸ͦΕͧΕΕΔɻ3 ੈ୅ͷχϡʔτϦϊΛେ౷‫Ͱܭ‬ଌఆ͢Δ͜ͱʹ໿ 6000 ൓Ԡͱ 5000 ൓ԠͰ͋Δɻ่֤յϞʔυຖͷৄΑΓϨϓτϯීวੑͷ‫ূݕ‬Λߦ͏ɻ͔͠͠ͳ͕Βɼ൓ԠࡉΛද 2 ʹࣔ͢ɻCES ʹΑΓ hadronic decay ͷిՙΛஅ໘ੵͷΑ͏ͳઈର஋ͷଌఆʹ͓͍ͯ͸λ΢χϡʔτϦܾఆग़དྷΔࣄʹΑΓਖ਼൓λ΢χϡʔτϦϊΛࣝผͰ͖Δ

ϊϑϥοΫεͷෆఆੑ͕શͯΛܾఆ͢Δ͜ͱʹͳͬͯ͠8122·͏ɻͦͷͨΊʹ DsTau/NA65 ࣮‫ݧ‬͸ SHiP ʹ͓͚Δ
λ΢χϡʔτϦϊͷ൓Ԡஅ໘ੵଌఆʹͱͬͯ͸ෆՄܽͷ

5

࠷‫ʹޙ‬
CERN SPS ʹ͓͚Δ DsTau/NA65 ࣮‫͓ݧ‬Αͼ SHiPલఏ࣮‫ͳͱݧ‬Δɻ΋͏ҰͭͷॏཁͳςʔϚͱͯ͠͸χϡʔτϦϊ൓Ԡ‫ܭ‬ըΛ঺հͨ͠ɻλ΢χϡʔτϦϊͷ෺ཧɼhidden sectorʹ͓͚Δॏ͍ΫΥʔΫͷੜ੒্͕͛ΒΕΔɻ͜ͷ Bαʔνɼintrinsic charm study Λ‫ؚ‬ΉνϟʔϜͷ‫ͳڀݚ‬anomaly ͕ΈΒΕΔ่յ B → Dτ ν τ ͷμΠΞάϥϜʹ

ͲΛɼ೔ຊਓάϧʔϓ͕த৺ͱͳͬͯࠃࡍ‫ڞ‬ಉ‫ʹڀݚ‬Α͓͍ͯɼχϡʔτϦϊΛࠨลʹҠಈͤ͞Ε͹λ΢χϡʔτΓਪਐ͍ͯ͠ΔɻDsTau/NA65 ͸ 2021-2022 ೥ʹঝೝϦϊ൓ԠʹΑΔνϟʔϜཻࢠੜ੒ͱࠅࣅ͓ͯ͠Γɼҧ͍͸͞Ε͍ͯΔ෺ཧϥϯɼSHiP ͸ 2020 ೥୅‫ޙ‬൒͔Β‫ܭ‬ըb,d ΫΥʔΫ͚ͩͰ͋Δɻߴ͍ੈ୅ͷχϡʔτϦϊ͕ॏ͍͞Ε͍ͯΔ࣮‫ʹݧ‬ΑΓɼϢχʔΫͳσʔλΛఏ‫͖Ͱڙ‬Δ

ΫΥʔΫʹΧοϓϧ͢Δ৽෺ཧ͕͋Ε͹ɼBelleɼBaBarɼ
LHCb ͱ͸શ͘ҟͳΔΞϓϩʔνͰͷ‫͕ূݕ‬ՄೳͰ͋Δɻ‫ڵ‬ຯਂ͍͜ͱʹ͜ͷ΄Ͳ OPERA ͸λ΢χϡʔτͱߟ͍͑ͯΔɻϦϊʹΑΔνϟʔϜੜ੒ͷॳ‫ݕ‬ग़ (ντ N → τ D 0 N � ) Λใࠂͨ͠ [15]ɻͨͬͨ 1 ྫͰ͸͋Δ͕‫ظ‬଴Λ͍ͯ͠ͳ͔ͬ

ͨνϟωϧʢ‫ظ‬଴஋ 0.1 ࣄ৅ʣͷ‫ݕ‬ग़Ͱ͋Γɼ‫͖ڻ‬ΛӅͤͳ͍ɻ͜Ε΋·ͨߴ͍ੈ୅ʹ‫͘ڧ‬ಇ͘৽෺ཧͷӨ‫Ͱڹ‬
͋ΔՄೳੑͰ͋ΓɼSHiP Ͱͷେ౷‫ܭ‬ͷ ντ Λ༻͍ͯ໌Β͔ʹ͢Δ͜ͱΛ‫ظ‬଴͍ͯ͠Δɻ͜ͷ‫Ͱূݕ‬͸χϡʔτϦϊʹΑΔνϟʔϜੜ੒ൺͰϨϓτϯීวੑ͕ഁΒΕΔͱ͍͏‫؍Ͱܗ‬ଌ͞ΕΔ͸ͣͰ͋cX νN →lcX
ΓɼR(D) ͱಉ༷ʹ RR(c) = ννττNN→τ→τ X / νN →lX ͷΑ

6ँࣙຊ‫ڀݚ‬͸ɼDsTau Collaboration (ຊ‫ࣄه‬ͷஶऀΒͷଞɼத໺හߦࢯɼ࿡ᑍ޺‫ࢯل‬ɼ٢ా७໵ࢯɼࣇ‫߁ۄ‬Ұࢯɼ੨໦ໜथࢯɼதଜޫኍࢯΒ)ɼSHiP Collaboration ʹΑͬͯ਱ߦ͓ͯ͠ΓɼSPS Ճ଎‫ث‬ͷํʑɼSPS Coordinatorɼ໊‫ݹ‬԰େֶάϧʔϓΒ༷ʑͳํʑʹࢧ͑ΒΕ͍ͯΔɻ
·ͨɼՊ‫ݚ‬අʢ17H02887ɼ18KK0085ʣͷॿ੒Λड͚͍ͯΔɻ͏ͳ double ratio ΛͱΔ͜ͱͰϑϥοΫεͷෆఆੑʹ΋‫͕ূݕ͍ڧ‬ՄೳͰ͋Δɻද 3 ʹɼGENIE [16] ʹΑͬͯ‫ظ‬଴͞ΕΔిࢠɾϛϡʔχϡʔτϦϊ൓ԠͰͷνϟʔ

[1] S. Aoki et al. [DsTau Collaboration], DsTau:
study of tau neutrino production with 400 GeVϜཻࢠੜ੒ͱੜ੒཰Λࣔ͢ɻද 3: ՙిΧϨϯτ DIS ൓Ԡ਺ͰͷνϟʔϜੜ੒൓Ԡͱ
ੜ੒཰

Nν e
Nν μ

�E�
[GeV]

CC DIS
with charm

Charm frac.
[%]66

6.0 × 104

5.7

55

Nν e

57

Nν μ

49

Total

1.3 × 105

4.7

4

5.1

2.5 × 104

4.2

1.3 × 10
2.3 × 10ࢀߟจ‫ݙ‬

5

໿ 6000ɼ5000 ͷਖ਼൓λ΢χϡʔτϦϊ൓Ԡʹରͯͦ͠ΕͧΕ 300 ൓Ԡͷ charm ੜ੒ࣄ৅͕‫ظ‬଴͞ΕΔɼB

anomaly ʹΈΒΕΔͷͱಉఔ౓ͷ 15%Λ௒͑ΔҟৗͰ͋Ε͹े෼ʹ‫؍‬ଌՄೳͰ͋Δɻ
৽෺ཧ΁ͷࢳ‫͔ͭݟͰ͜Ͳ͕ޱ‬Δ͔Θ͔Βͳ͍‫ݱ‬ঢ়Ͱ͸ҰͭҰͭՄೳੑΛͭͿ͍ͯ͘͠஍ಓͳ౒ྗ͕ඞཁͰ͋
ΔɻஶऀΒ͸ DONuTɼOPERA Ͱഓ͖ͬͯͨଞʹ͸ແ͍λ΢χϡʔτϦϊͷ‫ݕ‬ग़ٕज़Ͱ৽෺ཧʹ௅ΜͰ͍͘ɻ

protons from the CERN-SPS. J. High Energ.
Phys. 2020, 33 (2020).
[2] Y.S. Amhis et al. [HFLAV Collaboration], Averages of b-hadronɼc-hadron, and τ -lepton properties as of 2018. [arXiv:1909.12524].
[3] S. Alekhin et al., A facility to Search for Hidden
Particles at the CERN SPS: the SHiP physics
case, Rept. Prog. Phys. 79 (2016), no. 12 124201.
[arXiv:1504.04855].
[4] J. Beacham et al., Physics Beyond Colliders at
CERN: Beyond the Standard Model Working
Group Reportɼ2019. [arXiv:1901.09966].
[5] A.V. Giannini, V.P. Goncalves, and F.S.
Navarra, Intrinsic charm contribution to theprompt atmospheric neutrino ﬂux, Physical Review D 98 (2018) 014012.
[6] Weidong Bai, Mary Hall Reno, Prompt neutrinos and intrinsic charm at SHiP, J. High Energ.
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