Sgoldstino rate estimates in the SHiP experiment

Transcription

1 Sgoldstino rate estimates in the SHiP experiment Konstantin Astapov and Dmitry Gorbunov INR & MSU EMFCSC 2016, ERICE June 17, 2016 Konstantin Astapov and Dmitry Gorbunov Sgoldstino (INR rate & MSU) estimates in the SHiP experimentjune 17, / 18

2 Outlook Motivation SHiP experiment setup Introduction into sgoldstino model Scalar production scheme Scalar decay pattern Detection Pseudoscalar production scheme Pseudoscalar decay pattern Flavor violating case Summary Based on Phys. Rev. D 93, no. 3, (2016) [arxiv: [hep-ph]]. Konstantin Astapov and Dmitry Gorbunov Sgoldstino (INR rate & MSU) estimates in the SHiP experimentjune 17, / 18

3 Motivation To probe weak couplings between New Physics and SM at low mass scale we need high intensity experimental setup in contrast of high luminosity experiments. The CERN Super Proton Synchrotron (SPS) provides us with a high intensity beam of 400 GeV protons, and the recently proposed beam-dump Search for Hidden Particles (SHiP) experiment can perform the task. SM Konstantin Astapov and Dmitry Gorbunov Sgoldstino (INR rate & MSU) estimates in the SHiP experimentjune 17, / 18

4 SHiP: production of hidden particles 400 GeV proton beam from SPS POT intensity frontier. Molybdenum - Tungsten target. Goal: reduce the ν µ background by stopping charged pions Active muon shielding 50 m of tungsten + sophisticated configuration of magnetic field. Idea: place detector close to target. Konstantin Astapov and Dmitry Gorbunov Sgoldstino (INR rate & MSU) estimates in the SHiP experimentjune 17, / 18

5 SHiP: detection of hidden particles ν τ detector: OPERA-type bricks with a total mass of about 9.6 tonnes Decay volume: evacuated vessel (expensive as submarine) m 3. Pressure 10 6 bar. Tracker, calorimeter and muon detector: reconstruct a vertex in the decay volume. Konstantin Astapov and Dmitry Gorbunov Sgoldstino (INR rate & MSU) estimates in the SHiP experimentjune 17, / 18

6 Introduction into sgoldstino model Take a look at the MSSM Lagrangian. It consists of SUSY invariant and SUSY soft-breaking parts. L SUSY = L gauge + L Kähler + L superpotential + L breaking L breaking = ( 1 m 2 k φ k 2 ) + M α Trλ α λ α + h.c. 2 k α ( ) ɛ ij Bh i Dh j U + AL ab l j aẽ c bh i D + A D ab q j a d c bh i D + A U ab q i aũ c bh j U + h.c. This is an effective Lagrangian of low energy case of some high energy SUSY invariant theory. Supersymmetry is supposed to be broken at low energy scale F. Konstantin Astapov and Dmitry Gorbunov Sgoldstino (INR rate & MSU) estimates in the SHiP experimentjune 17, / 18

7 Introduce L S MSSM Lagrangian. L S MSSM = L S Kähler + L S gauge + L S superpotential L S gauge = 1 2 d 2 θ S + AL ab F Lj ae c bh i D + AD ab F Sgoldstino supermultiplet. all gauge fields M α F TrWα W α + h.c. ( L S superpotential = d 2 θ S ɛ ij B F Hi DH j U + Qj ad c bh i D + AU ab F S = s + 2θ s + F S θ 2 ) Qi au c bh j U + h.c F S acquires its vev F, then using spurion method L S MSSM L breaking +L int, where L eff is the Lagrangian of interaction of scalar sgoldstino and MSSM particles. Konstantin Astapov and Dmitry Gorbunov Sgoldstino (INR rate & MSU) estimates in the SHiP experimentjune 17, / 18

8 Motivation for sgoldstino If supersymmetry is spontaneously broken at not very high energy scales the particles from the SUSY breaking sector may show up at quite low energies. Their effective couplings to the SM particles are anticipated to be rather weak; therefore a high intensity beam is required to test the model via production of the new particles. onstantin Astapov and Dmitry Gorbunov Sgoldstino (INR rate & MSU) estimates in the SHiP experimentjune 17, / 18

9 Basic phenomenological assumptions Effective Lagrangian ( ) L eff = 1 2 m 2 S 2F S G G + im 2 P P Gγ 5 G 1 2 M γγ 2 F SFµν F µν M γγ 2 F Pɛµνρσ F µν F ρσ 1 2 M 3 2 F SGµν a G a µν M 3 2 F Pɛµνρσ G a µν Ga ρσ m LR D 2 ij S f Di f Dj i 2F m LR D 2 ij P f Di γ 5 f Dj 2F m LR U 2 ij S f Ui f Uj i 2F m LR U 2 ij P f Ui γ 5 f Uj 2F (1) m LR L 2 m LR ij L 2 ij S f Li f Lj i P f Li γ 5 f Lj. 2F 2F MSSM benchmark point MSSM benchmark point table is chosen to satisfy MSSM experimental bounds and make lightest Higgs scalar mass to be 125 GeV. M 1, GeV M 2, GeV M 3, GeV µ, GeV tan β m A, GeV A l, GeV m l, GeV A Q, GeV m Q, GeV onstantin Astapov and Dmitry Gorbunov Sgoldstino (INR rate & MSU) estimates in the SHiP experimentjune 17, / 18

10 Production at fixed target Two main production channels: 1 Direct production. In the case of the SHiP experiment it corresponds to hadron-level: pp S SM 2 Production in radiative meson decays: B ± K ± S, S SM σ(pn S SM) = σ(pn S)Br(S SM) Konstantin Astapov and Dmitry Gorbunov Sgoldstino (INR rate & MSU) estimates in the SHiP experiment June 17, / 18

11 Scalar production σ pp S (P)/σpp,total Scalar production via gluon fussion ( L Sgg = αs(m S)β(α s(m 3 )) M 3 β(α s(m S ))α s(m 3 ) 2 2F θ g one loop (m hgg S ) ) SG µν a G a µν, m S (P), GeV Gluon fusion B meson decays Scalar production via B-meson decays d 3 σ pp S(P) dpdθ pdφ p = d 3 d k f( p, 3 σ B k) dkdθ k dφ k σ pp S (P)/σpp,total m S (P), GeV f( p, k) is the sgoldstino momentum distribution function. = 0.3 ( mt m W ) 4 ( 1 m2 S m 2 b Br(B X ss) = ) 2 (A Q v + Fθ) 2 ( ) TeV F F = 1000 TeV F = 100 TeV onstantin Astapov and Dmitry Gorbunov Sgoldstino (INR rate & MSU) estimates in the SHiP experiment June 17, / 18

12 Scalar decay pattern Br S m S, GeV γγ e + e - μ + μ - ππ KK Considering scalar decay channels γγ, e + e, µ + µ, π 0 π 0, π + π, K + K, K 0 K 0 Using chiral theory approach when calculating meson modes Γ(S γγ) = ( ) 2 α(ms )β(α(m γγ )) m 3 S(P) M2 γγ = β(α(m S ))α(m γγ ) 32πF 2 Γ(S l + l ) = m3 S A2 2 m l l 16πF 2 m 2 S ( ) 1 4m2 l 3/2 m 2 S τ, sec Γ(S π 0 π 0 ) = α2 s (M 3) πm S β 2 (α s(m 3 )) 4 m 2 S M2 3 F 2 4m 2 π 1 0 m 2, S m S, GeV F = 1000 TeV F = 100 TeV onstantin Astapov and Dmitry Gorbunov Sgoldstino (INR rate & MSU) estimates in the SHiP experiment June 17, / 18

13 Detection Number of signal events reads as: N signal = N POT dσ pp S(P) w det d 3 p σ pp,total dpdθ pdφ p F -1/2, (100 TeV) Probability for the sgoldstino to decay inside the fiducial volume of the detector: w det (E S(P), m S(P), F) = = exp( l sh /γcτ S(P) ) [ ] 1 exp( l det /γ(e S(P) )cτ S(P) ) m S, GeV The upper boundary in the picture is the region where the sgoldstino coupling constants 1/F are large enough to initiate very fast decay of the sgoldstino before it reaches the detector. The lower boundary in the picture is the region where the couplings are so small that sgoldstinos escape from the detector without decay.n signal M 2 3 µ6 /F 4 m S 3.6 GeV, is the meeting point of the lower and the upper boundaries, here the sgoldstino decay length is about 100 m. In this case the number of signal events scales as N signal µ 6 /F 2 onstantin Astapov and Dmitry Gorbunov Sgoldstino (INR rate & MSU) estimates in the SHiP experiment June 17, / 18

14 Pseudoscalar production The pseudoscalar sgoldstino P can be directly produced via the gluon fusion with the same cross section as the scalar sgoldstino; However, its production through the meson decays is somewhat different from that of the scalar sgoldstino because of the absence of mixing with the light MSSM Higgs. The light pseudoscalar also can be produced in B-meson decays. Given the pseudoscalar nature of P, for the two-body decay it is accompanied by the vector kaon K. The decay rate can be obtained using result for the case of decay into the axion, where we assume charged the Higgs boson mass m H to be approximately 1 TeV, which follows from the value of m A given in Table U 33 4 Γ(B K P) = G2 F m2 t m RL 2 13 π 3 2 F 2 cot2 β(ˆx 1 + cot 2 β ˆX 2 ) 2 A2 0 λ3 B K, m 3 B Konstantin Astapov and Dmitry Gorbunov Sgoldstino (INR rate & MSU) estimates in the SHiP experiment June 17, / 18

15 Pseudoscalar decay pattern and number of events Br P m P, GeV γγ e + e - μ + μ - 3π 0 π 0 ηη π 0 π + π - π 0 KK 3η 2π 0 η ηkk F -1/2, (100 TeV) τ, sec m P, GeV F = 1000 TeV F = 100 TeV m P, GeV P π 0 /η 3 mesons Pseudoscalar decay channels are determined by its admixture in π 0 and η, which can decay into 3 pseudoscalar mesons. onstantin Astapov and Dmitry Gorbunov Sgoldstino (INR rate & MSU) estimates in the SHiP experiment June 17, / 18

16 Flavor violating case In supersymmetric models with nondiagonal sfermion left-right mass terms, m LR D 2 ij / δ ij, etc, sgoldstino couplings violate flavor symmetry. These flavor-violating terms are additional sources of sgoldstino production. We consider flavor-violating decays of B and D s mesons into kaons and light scalar sgoldstinos. These processes are governed by the soft parameters m LR D 2 23 and m LR U Observation of oscillations in the B 0 B 0 and D 0 D 0 systems and searches for very rare (within the SM) decays like B µ + µ constrain possible flavor violation in the squark sector, which for our reference point given in Table imposes the following upper limits on the off-diagonal entries, m LR 2 D 23 < 0.02 TeV 2, m LR 2 U 12 < TeV 2. Konstantin Astapov and Dmitry Gorbunov Sgoldstino (INR rate & MSU) estimates in the SHiP experiment June 17, / 18

17 F -1/2, (100 TeV) -1 F -1/2, (100 TeV) -1 Flavor violating case for scalar ms, GeV F -1/2, (100 TeV) -1 F -1/2, (100 TeV) -1 3 mp, GeV ms, GeV On the lower boundary Nsignal mp, GeV 4 m LR M2 /F4 D23 (U12 ) 3 In particular, the process B Ks + S(P) with sgoldstinos subsequently decaying outside the detector can mimic the process B h( ) + missing, whose branching is presently constrained as 5 Br(B K0 S ν ν ) < Konstantin Astapov and Dmitry Gorbunov Sgoldstino (INRrate & MSU) estimates in the SHiP experiment June 17, / 18

18 Summary We have estimated sensitivity of the SHiP experiment to supersymmetric extensions of the SM where sgoldstinos are light. The proposed experiment will be able to probe a lower SUSY breaking scale scalar sgoldstino F up to 10 3 TeV for the model without flavor violation and up to 10 5 TeV for the model with flavor-violating parameters as large as the corresponding present experimental up- per bounds. We have also compared the regions of the sgoldstino parameter space to be probed at the SHiP experiment with the regions that we have excluded from the analysis of the results of the CHARM experiment Here we concentrate mostly on sgoldstino masses in the range 0.4 4GeV, where sgoldstino can be kinematically produced in decays of charm and beauty mesons. Lighter sgoldstinos can, in addition, be produced at the SHiP by strange meson decays. This possibility deserves a special study beyond the scope of this work. Konstantin Astapov and Dmitry Gorbunov Sgoldstino (INR rate & MSU) estimates in the SHiP experiment June 17, / 18