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Flavour violating squark and gluino decays at LHC. K. Hidaka Tokyo Gakugei University In collaboration with A. Bartl, H. Eberl, E. Ginina, B. Herrmann, W. Majerotto and W. Porod (A part of this work is published in Phys. Rev. D84 (2011) 115026; arXiv:1107.2775 [hep-ph].) - PowerPoint PPT Presentation
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Flavour violating squark and gluino decays at LHC
K. HidakaTokyo Gakugei University
In collaboration withA. Bartl, H. Eberl, E. Ginina, B. Herrmann, W. Majerotto and W. Porod
(A part of this work is published in Phys. Rev. D84 (2011) 115026; arXiv:1107.2775 [hep-ph].)
ICHEP2012, 6 July 2012, Melbourne
Contents1. Introduction
2. MSSM with Quark Flavour Violation (QFV)
3. Constraints on the MSSM
4. QFV gluino 3-body decays 4.1 QFV Benchmark Scenario for gluino decays 4.2 Impact of squark generation mixing on gluino 3-body decays 4.3 Impact on gluino signals at LHC
5. QFV squark bosonic decays 5.1 QFV Benchmark Scenario for Squark decays 5.2 Impact of squark generation mixing on squark bosonic
decays 5.3 Impact on squark signals at LHC
6. Conclusion
• If weak scale SUSY is realized in nature, gluinos and squarks will have high production rates for masses up to O(1) TeV at LHC.
• The main decay modes of gluinos and squarks are usually assumed to be quark-flavour conserving (QFC).
• However, squark generation mixings can induce quark-flavour violating (QFV) decays of gluinos and squarks.
• Here we study the effect of squark generation mixing on squark and gluino production and decays at LHC in the general MSSM with focus on mixing between 2nd and 3rd generation squarks.
1. Introduction
2. MSSM with QFV• The basic parameters of the MSSM with QFV:
tantanmA ,MM11MM22MM33 ,MM22Q,Q,MM22
U,U, M M22D,D,TTUUTTDD
at Q = 1TeVat Q = 1TeV scale (SPA convention) scale (SPA convention)((u, c, t or d, s, u, c, t or d, s, b)b)
tantan ratio of VEV of the two Higgs doublets <Hratio of VEV of the two Higgs doublets <H00 22>/<H>/<H0011>>
mA : CP odd Higgs boson mass (pole mass)
MM1,1, M M22 ,M ,M3 3 : : U(1), SU(2),SU(3) gaugino massesU(1), SU(2),SU(3) gaugino masses
higgsino mass parameterhiggsino mass parameter
MM22Q,Q,left squarkleft squarksoft mass matrixsoft mass matrix
MM22UU right up-type squark right up-type squarksoft mass matrixsoft mass matrix
MM22DD right down-type squark right down-type squarksoft mass matrixsoft mass matrix
TTUUtrilinear coupling matrix of up-type squark and Higgs bosontrilinear coupling matrix of up-type squark and Higgs boson
TTDD trilinear coupling matrix of down-type squark and Higgs bosontrilinear coupling matrix of down-type squark and Higgs boson
2,23LM
2
,23EM
23A
32A
L L
R R
L R
R L
QFV parameters in our study are:
MM22Q,Q, : mixing term
MM22UU : mixing term
TTUU : mixing term
TTUU : mixing term
(Note) We work in the super-CKM basis of squarks. .
LL tc ~~ RR tc ~~ RL tc ~~ LR tc ~~
Recent ATLAS and CMS SUSY searches at 7TeV with ~1-5 fb-1
In a simplified model;
gluino mass > 800 GeV squark mass > 850 GeV (for 1st & 2nd generation squarks)
In the context of the CMSSM (mSUGRA);
gluino mass > 840 GeV squark mass > 1100 GeV (for 1st & 2nd generation squarks)
Respecting these limits, we assume a gluino mass of about
1 TeV in our analysis
(Note) We also respect the constraint on (mA , tantan) from the recent
MSSM Higgs boson search at LHC [arXiv:1202.4083].
3. Constraints on the MSSM
The following constraints are imposed in our analysis in order to respect experimental and theoretical constraints:
(a) Constraints from the B-physics experiments :
(b) LEP limits on sparticle masses
(ex) etc.
(c) The experimental limit on SUSY contributions to the electroweak parameter:
(d) Vacuum stability conditions on trilinear couplings (see J.A. Casas and S. Dimopoulos, Phys. Lett. B 387 (1996) 107 [hep-ph/9606237].)
(ex)
)(|| 22
233
222
2223 mMMhT UQtU u
22122222
2 cos)sin( ZWZHmmmm
GeVm 1031
~
0012.0)( SUSY
(HFAG2010) CL) (95% 10 4.23 < ) s B(b 102.87 -4-4 BABAR)(BELLE, CL) (95% )or e=(with 10 2.60 < ) s B(b <100.60 -6--6
(LHCb) CL) (95% 10 4.5 < ) B(B -9-s
BABAR)(BELLE, CL) (68% 10 0.31) (1.68 = ) B(B -4u
(CDF) CL) (68% ps 0.12 17.77 =M -1Bs
(LHCb) CL) (68% ps 0.11 17.63 =M -1Bs
We take the following scenario as our prototype QFV scenario:
We add QFV parameters (i.e. squark-generation mixing parameters) to this scenario:
MM22Q,Q,MM22
U,U, M M22D,D,TTUUTTDD (
4. QFV gluino 3-body decays
4.1 QFV Benchmark Scenario
< up-squark sector > < down-squark sector >
Prototype QFV scenario
Rum~
gm~
Lum~
Lcm~
Ltm~
Rbm~
Rdm~
Rsm~
gm~
Ldm~
Lsm~
Lbm~
Rtm~
Rcm~
We add mixing to this scenarioRR tc ~~
TeV3~
TeV2~
TeV1~
< up-squark sector > < down-squark sector >
Rum~
gm~
Lum~
Lcm~
Ltm~
Rbm~
Rdm~
Rsm~
gm~
Ldm~
Lsm~
Lbm~
Rtm~
Rcm~
RR tc ~~
In this large mixing scenario all squarks other than are very heavy.So, gluino decay is dominated by virtual exchange.
1~um
2~um
1~u
1~uRR tc ~~
In this large mixing scenario;
• Gluino decay is dominated by virtual exchange contribution.
• is a strong mixture of and .
QFV branching ratio could be very large!
RR tc ~~ 1
~u
1~u Rc~ Rt~
)~~( 01tcgB
QFV gluino decay branching ratio can be very large (up to ~40%) for large mixing parameter !
)~~()~~( 01
01 ctgBtcgB QFV decay BR
mixing parameterRR tc ~~
uRR
23RR tc ~~
uRR
23
BR
(glu
ino
→ 3
-bod
y)
)~~( 01ctgB
4.2 Impact of squark generation mixing on gluino 3-body decays
Contour plots of Contour plots of QFVQFV BR in our BR in our scenario
contours
)~~( 01ctgB
mixing parameterRR tc ~~
mixing parameterLL tc ~~
The QFV decay branching ratio can be very large (up to ~40%) in a
significant part of the plane allowed by all of the constraints.
)~~( 01ctgB
uRRuLL
2323
This can lead to large QFV effects at LHC!
excluded by data) s B(b
excluded by dataBsM
Gluino pair production and the QFV gluino 3-body decay lead to
QFV gluino signature at LHC :
XctctXggpp )~)(~(~~ 01
01
01
~~ ctg
blbWt
‘top-quark + top-quark + 2 jets + missing-ET + beam-jets‘
‘isolated same sign dilepton + 4 jets + missing-ET + beam-jets‘
Example of QFV gluino signal at LHC
4.3 Impact on gluino signals at LHC
p pgg
c
isolated same sign dilepton
l 'l
‘isolated same sign dilepton + 4 jets + missing-ET + beam-jets‘
c
bb
QFV gluino signal rates at LHC
QFV signal rates such as
can be significant for large mixing parameter at LHC!
mixing parameterRR tc ~~ uRR
23
)~~~~( 01
01 XEccttXccttXggpp mis
T uRR
23RR tc ~~
We take the following scenario as our prototype QFV scenario:
We add QFV parameters (i.e. squark-generation mixing parameters) to this scenario: M M22
Q,Q,MM22U,U,
MM22D,D,TTUUTTDD (
5. QFV squark bosonic decays5.1 QFV Benchmark Scenario
These weak scale parameters are defined at Q = 1 TeV scale (SPA convention).
(M1, M2 ,M3) = (450, 855, 1000) GeV
= 2400 GeV, tan = 20, mA(pole) = 1500 GeV
(M^2_Q11, M^2_Q22, M^2_Q33) = (2400^2, 2360^2, 1450^2) GeV^2
(M^2_U11, M^2_U22, M^2_U33) = (2380^2, 780^2, 750^2) GeV^2
(M^2_D11, M^2_D22, M^2_D33) = (2380^2, 2340^2, 2300^2) GeV^2 All of TU and TD are zero, except TU = -2160 GeV.
decoupling Higgs scenario
large mixing scenario (large top-trilinear-coupling scenario)
RL tt ~~
Physical masses in the prototype QFV scenario
These masses are fairly insensitive to the QFV parameters.
= 125.5 GeV
- CP-even lighter Higgs boson h0 is SM-like!
- its mass mh0 = 125.5 GeV is in the LHC “possible Higgs signal” range ! : 122 < mh0 < 128GeV.
0hm
GeVmmmAHH
150000
GeVm poleg 1141~
< up-squark sector > < down-squark sector >
Prototype QFV scenario
Rum~
gm~
Lum~
Lcm~
Ltm~
Rbm~
Rdm~
Rsm~
gm~
Ldm~
Lsm~
Lbm~
Rtm~
Rcm~
We add mixing to this scenarioRR tc ~~
TeV4.2~
TeV8.0~
TeV14.1~
TeV45.1~
large mixingRL tt ~~
< up-squark sector > < down-squark sector >
Rum~
gm~
Lum~
Lcm~
Ltm~
Rbm~
Rdm~
Rsm~
gm~
Ldm~
Lsm~
Lbm~
Rtm~
Rcm~
could be sizable!
TeV4.2~
TeV8.0~
TeV14.1~
TeV45.1~
RR tc ~~ 1
~um
2~um
)~~( 012 huuB
large mass splitting between and !1
~um2
~um
In this large & mixing scenario;
QFV branching ratio can be large!
RR tc ~~ RL tt ~~ LRR tctu ~~~~
~1
LRR ttcu ~~~~~2
02~
0 Hh2
~u
02~
0 HhLR tt ~~
~
1~u
LR tt ~~~
In our scenario "top trilinear coupling“ ( coupling) = TU is large!
coupling is large!
)~~( 012 huuB
02
~~ Htt RL
021
~~ huu
In this large & mixing scenario;
QFV BR can be large!
RR tc ~~ RL tt ~~
LRR tctu ~~~~~1
1~u
01
~
tc /
RR ct ~~~
)~/~( 011 tcuB
QFV BR can be large!)~/~~( 01
0012 htchuuB
QFV squark decay branching ratio can be very large (up to ~50%) for large mixing parameter !
QFV decay BR
uRR
23RR tc ~~
)~~( 012 huuB
)~~( 012 huuB
mixing parameterRR tc ~~
5.2 Impact of squark generation mixing on squark bosonic decays
QFV squark decay BR can be very large simultaneously for sizable mixing parameter !
QFV decay BR
uRR
23RR tc ~~
)~/~( 011 tcuB
)~/~( 011 tcuB
mixing parameterRR tc ~~
We have obtained a similar result for dependence of QFV BR and !:
can be very large (up to ~50%) for large mixing parameter !
LR tc ~~
Lt~
Lc~
Rt~uRR
23
uRL
23
uRL
33Rc~
uRL
23
)~~( 012 huuB )~/~( 0
11 tcuB )~~( 0
12 huuB uRL
23
Gluino pair production and the QFV squark bosonic decay can lead to
QFV squark signature at LHC :
)~~()~)(~(
)~)(~()~)(~(~~
01
01
00001
001
01
0122
XhhccttXchtcht
XchuchuXcucuXggpp
‘2 top-quarks + 2 jets + 2 h0 + missing-ET + beam-jets‘
Example of QFV squark signal at LHC
blbWt
‘isolated same sign dilepton + 4 jets + 2 h0 + missing-ET + beam-jets‘
5.3 Impact on squark signals at LHC
p pgg
c
isolated same sign dilepton
l 'l
c
bb
‘isolated same sign dilepton + 4 jets + 2 h0 + missing-ET + beam-jets‘
0h0h
h0 decay branching ratios
• B(h0 tau- tau+) = 9.1%
• B(h0 b b_bar) = 57.3%
• B(h0 photon photon) = 0.52%
• B(h0 W W*) = 22.7%
• B(h0 Z Z*) = 2.5%
h0 is SM-like in our scenario!
QFV squark signal rates at LHC
QFV squark signal rates can be significant
at LHC(14 TeV)!
In our scenario;
- gluino prod. cross section is significant:
~ 80 fb at LHC(14 TeV)!
- can be large (~ 25 %)!
We can expect copious production of
from gluino prod. and decays at LHC(14 TeV)!
)~~( Xggpp )/~~( 2 tcugB
2~u
Our analyses suggest the following:
•One should take into account the possibility of significant
contributions from QFV decays in the squark and gluino
search at LHC.
• Moreover, one should also include QFV squark parameters
(i.e. squark–generation mixing parameters) in the determination
of the basic SUSY parameters at LHC.
6. Conclusion
• We have studied production and decays of squarks and gluinos in the MSSM with
squark generation mixing, especially mixing.
• We have shown that QFV squark and gluino decay branching ratios such as
, , can be very large (up to ~50%) due to
the mixing in a significant region of the QFV parameters despite the
very strong constraints from B meson data.
• This can result in remarkable QFV squark and gluino signal events such as
‘ + beam-jets’ and ‘ + beam-jets’
with a significant rate at LHC(14 TeV).
• These could have an important impact on the search for squarks and gluinos and the MSSM parameter determination at LHC.
LRLR tc //~~
)~~( 01ctgB )~/~( 0
11 tcuB )~~( 012 huuB
misTEccttpp mis
TEhhccttpp 00
LRLR tc //~~
Backup Slides
Flavour violating squark and gluino decays at LHC
K. HidakaTokyo Gakugei University
In collaboration withA. Bartl, H. Eberl, E. Ginina, B. Herrmann, W. Majerotto and W. Porod
(A part of this work is published in Phys. Rev. D84 (2011) 115026; arXiv:1107.2775 [hep-ph].)
ICHEP2012, 6 July 2012, Melbourne
Contents1. Introduction
2. MSSM with Quark Flavour Violation (QFV)
3. Constraints on the MSSM
4. QFV gluino 3-body decays 4.1 QFV Benchmark Scenario for gluino decays 4.2 Impact of squark generation mixing on gluino 3-body decays 4.3 Impact on gluino signatures at LHC
5. QFV squark bosonic decays 5.1 QFV Benchmark Scenario for Squark decays 5.2 Impact of squark generation mixing on squark bosonic
decays 5.3 Impact on squark signatures at LHC
6.Impact on squark and gluino search at LHC
7. Conclusion
• If weak scale SUSY is realized in nature, gluinos and squarks will have high production rates for masses up to O(1) TeV at LHC.
• The main decay modes of gluinos and squarks are usually assumed to be quark-flavour conserving (QFC).
• However, the squarks are not necessarily quark-flavour eigenstates.
The flavour mixing in the squark sector may be stronger than that in the quark sector.
In this case quark-flavour violating (QFV) decays of gluinos and squarks could occur.
• Here we study the effect of the mixing of charm-squark and top-squark on the squark and gluino decays at LHC.
1. Introduction(1) Motivation;
(2)Purpose of this work;
• In this work we study the effect of squark generation mixing on squark and gluino production and decays at LHC in the general MSSM with focus on mixing between 2nd and 3rd generation squarks. • Taking into account the constraints from B-physics experiments , we show that various regions in parameter space exist where decays of squarks and/or gluinos into flavour violating final states can have large branching ratios of up to ~ 50%. Here we consider both fermionic and bosonic final states.
• This could have an important impact on the search for squarks and gluinos and the MSSM parameter determination at LHC.
2. MSSM with QFV• The basic parameters of the MSSM with QFV:
tantanmA ,MM11MM22MM33 ,MM22Q,Q,MM22
U,U, M M22D,D,TTUUTTDD
at Q = 1TeV scale (SPA convention)at Q = 1TeV scale (SPA convention)((u, c, t or d, s, u, c, t or d, s, b)b)
tantan ratio of VEV of the two Higgs doublets <Hratio of VEV of the two Higgs doublets <H00 22>/<H>/<H0011>>
mA : CP odd Higgs boson mass (pole mass)
MM1,1, M M22 ,M ,M3 3 : : U(1), SU(2),SU(3) gaugino massesU(1), SU(2),SU(3) gaugino masses
higgsino mass parameterhiggsino mass parameter
MM22Q,Q,left squarkleft squarksoft mass matrixsoft mass matrix
MM22UU right up-type squark right up-type squarksoft mass matrixsoft mass matrix
MM22DD right down-type squark right down-type squarksoft mass matrixsoft mass matrix
TTUUtrilinear coupling matrix of up-type squark and Higgs bosontrilinear coupling matrix of up-type squark and Higgs boson
TTDD trilinear coupling matrix of down-type squark and Higgs bosontrilinear coupling matrix of down-type squark and Higgs boson
2,23LM
2
,23EM
23A
32A
L L
R R
L R
R L
• We study mixing effect: QFV parameters in our study are:
MM22Q,Q, : mixing term (
mixing term)
MM22UU : mixing term
TTUU : mixing term
TTUU : mixing term
(Note) We work in the super-CKM basis of squarks: .
tc ~~
LL tc ~~ LL bs~~
RR tc ~~ RL tc ~~ LR tc ~~
)~
,~,~
,~
,~,~
(),~,~,~,~,~,~( RRRLLLRRRLLL bsdbsdtcutcu
Recent ATLAS and CMS SUSY searches at 7TeV with ~1-5 fb-1
In a simplified model;
gluino mass > 800 GeV squark mass > 850 GeV (for 1st & 2nd generation squarks)
In the context of the CMSSM (mSUGRA);
gluino mass > 840 GeV squark mass > 1100 GeV (for 1st & 2nd generation squarks)
Respecting these limits, we assume a gluino mass of about
1 TeV in our analysis
(Note) We also respect the constraint on (mA , tantan) from the recent
MSSM Higgs boson search at LHC [arXiv:1202.4083].
3. Constraints on the MSSM
The following constraints are imposed in our analysis in order to respect experimental and theoretical constraints:
(a) Constraints from the B-physics experiments :
(b) LEP limits on sparticle masses
(ex) etc.
(c) The experimental limit on SUSY contributions to the electroweak parameter:
(d) Vacuum stability conditions on trilinear couplings (see J.A. Casas and S. Dimopoulos, Phys. Lett. B 387 (1996) 107 [hep-ph/9606237].)
(ex)
3. Constraints on the MSSM (continued)
)(|| 22
233
222
2223 mMMhT UQtU u
22122222
2 cos)sin( ZWZHmmmm
GeVm 1031
~
0012.0)( SUSY
(HFAG2010) CL) (95% 10 4.23 < ) s B(b 102.87 -4-4 BABAR)(BELLE, CL) (95% )or e=(with 10 2.60 < ) s B(b <100.60 -6--6
(LHCb) CL) (95% 10 4.5 < ) B(B -9-s
BABAR)(BELLE, CL) (68% 10 0.31) (1.68 = ) B(B -4u
(CDF) CL) (68% ps 0.12 17.77 =M -1Bs
(LHCb) CL) (68% ps 0.11 17.63 =M -1Bs
(Note) We find that these constraints are very important:
and data => strongly constrain the QFV squark parameters
data => strongly constrain the QFV squark parameters
data => strongly constrain
Vacuum stability conditions => strongly constrain QFV trilinear couplings TUTD
sBM) s B(b
) B(Bu )tan,( Hm
(Note) We use the public code SPheno v3.1 in the calculation of the B-physics observables.
) B(B -s
We take the following scenario as our prototype QFV scenario:
We add QFV parameters (i.e. squark-generation mixing parameters) to this scenario:
MM22Q,Q,MM22
U,U, M M22D,D,TTUUTTDD (
4. QFV gluino 3-body decays
4.1 QFV Benchmark Scenario
Physical masses in the prototype QFV scenario
These masses are fairly insensitive to the QFV parameters.
(Note) We can easily push up to 125 GeV without changing
our final conclusion, for example, by taking
and !
0hm
20tan GeVm
A15000
< up-squark sector > < down-squark sector >
Prototype QFV scenario
Rum~
gm~
Lum~
Lcm~
Ltm~
Rbm~
Rdm~
Rsm~
gm~
Ldm~
Lsm~
Lbm~
Rtm~
Rcm~
We add mixing to this scenarioRR tc ~~
TeV3~
TeV2~
TeV1~
< up-squark sector > < down-squark sector >
“Prototype QFV scenario” + “large mixing”
Rum~
gm~
Lum~
Lcm~
Ltm~
Rbm~
Rdm~
Rsm~
gm~
Ldm~
Lsm~
Lbm~
Rtm~
Rcm~
RR tc ~~
In this large mixing scenario all squarks other than are very heavy.So, gluino decay is dominated by virtual exchange.
1~um
2~um
RR tc ~~
1~u
1~uRR tc ~~
In this large mixing scenario;
• Gluino decay is dominated by virtual exchange contribution.
• is a strong mixture of and .
QFV branching ratio could be very large!
RR tc ~~ 1
~u
1~u Rc~ Rt~
)~~( 01tcgB
We study the effect of squark generation mixing on gluino production and decays
at LHC for the case that the gluino is lighter than all squarks and dominantly
decays into three particles:
In case of mixing, gluino could decay as follows:
4.2 Impact of squark generation mixing on gluino 3-body decays
tc ~~
0~~iqqg jqqg ~'~
01
~~ tcg 01
~~ ctg
• Gluino decay branching ratios in our scenario:
QFV gluino decay branching ratio can be very large (up to ~40%) for large mixing parameter !
)~~()~~( 01
01 ctgBtcgB QFV decay BR
mixing parameterRR tc ~~
uRR
23RR tc ~~
uRR
23
BR
(glu
ino
→ 3
-bod
y)
)~~( 01ctgB
Contour plots of Contour plots of QFVQFV BR in our BR in our scenario
contours
)~~( 01ctgB
mixing parameterRR tc ~~
mixing parameterLL tc ~~
The QFV decay branching ratio can be very large in a significant part of
the plane allowed by all of the constraints.
)~~( 01ctgB
uRRuLL
2323
This can lead to large QFV effects at LHC!
Contour plots of Contour plots of QFVQFV BR in our BR in our scenario
contours
)~~( 01ctgB
mixing parameterRR tc ~~
mixing parameterLL tc ~~
The QFV decay branching ratio can be very large in a significant part of
the plane allowed by all of the constraints.
)~~( 01ctgB
uRRuLL
2323
This can lead to large QFV effects at LHC!
excluded by data) s B(b
excluded by dataBsM
We have obtained a similar result for the QFV 3-body decay branching ratio :
It can be as large as ~35%!
)~~()~~()~~( 01
01
01 bsgBbsgBbsgB
Neutralino/chargino parameter dependence of QFV BR
The branching ratios of the QFV 3-particle gluino decays depend quite strongly on the parameters of the neutralino/chargino sector!
contours in – M2 plane )~~( 01ctgB
4.3 Impact on gluino signatures at LHC
01
~~ ctg
The signature of the QFV gluino decay at LHC:
' top-quark + jet + missing-energy'
Large mixing RR tc ~~
Large QFV BR )~~( 01ctgB
01
~~ ctg
g~ c
t
01
~
Gluino pair production and the QFV gluino 3-body decay lead to
QFV gluino signature at LHC :
XctctXggpp )~)(~(~~ 01
01
01
~~ ctg
blbWt
‘top-quark + top-quark + 2 jets + missing-ET + beam-jets‘
‘isolated same sign dilepton + 4 jets + missing-ET + beam-jets‘
Example of QFV gluino signal at LHC
isolated same sign dilepton
‘isolated same sign dilepton + 4 jets + missing-ET + beam-jets‘
c
p p
gg
g
t
g~g~
tc
01
~0
1~
b bW
l
W
'l
jetbeam jetbeam
QFV gluino decay
Example of QFV gluino signal at LHC
p pgg
c
isolated same sign dilepton
l 'l
‘isolated same sign dilepton + 4 jets + missing-ET + beam-jets‘
c
bb
QFV gluino signal rates at LHC
QFV signal rates such as
can be significant for large mixing parameter at LHC!
mixing parameterRR tc ~~ uRR
23
)~~~~( 01
01 XEccttXccttXggpp mis
T uRR
23RR tc ~~
We take the following scenario as our prototype QFV scenario:
We add QFV parameters (i.e. squark-generation mixing parameters) to this scenario: M M22
Q,Q,MM22U,U,
MM22D,D,TTUUTTDD (
5. QFV squark bosonic decays5.1 QFV Benchmark Scenario
These weak scale parameters are defined at Q = 1 TeV scale (SPA convention).
(M1, M2 ,M3) = (450, 855, 1000) GeV
= 2400 GeV, tan = 20, mA(pole) = 1500 GeV
(M^2_Q11, M^2_Q22, M^2_Q33) = (2400^2, 2360^2, 1450^2) GeV^2
(M^2_U11, M^2_U22, M^2_U33) = (2380^2, 780^2, 750^2) GeV^2
(M^2_D11, M^2_D22, M^2_D33) = (2380^2, 2340^2, 2300^2) GeV^2 All of TU and TD are zero, except TU = -2160 GeV.
decoupling Higgs scenario
large mixing scenario (large top-trilinear-coupling scenario)
RL tt ~~
Physical masses in the prototype QFV scenario
These masses are fairly insensitive to the QFV parameters.
= 125.5 GeV
- CP-even lighter Higgs boson h0 is SM-like!
- its mass mh0 = 125.5 GeV is in the LHC “possible Higgs signal” range ! : 122 < mh0 < 128GeV.
0hm
GeVmmmAHH
150000
GeVm poleg 1141~
< up-squark sector > < down-squark sector >
Prototype QFV scenario
Rum~
gm~
Lum~
Lcm~
Ltm~
Rbm~
Rdm~
Rsm~
gm~
Ldm~
Lsm~
Lbm~
Rtm~
Rcm~
We add mixing to this scenarioLRLR tc //~~
TeV4.2~
TeV8.0~
TeV14.1~
TeV45.1~
large mixingRL tt ~~
< up-squark sector > < down-squark sector >
Rum~
gm~
Lum~
Lcm~
Ltm~
Rbm~
Rdm~
Rsm~
gm~
Ldm~
Lsm~
Lbm~
Rtm~
Rcm~
could be sizable!
TeV4.2~
TeV8.0~
TeV14.1~
TeV45.1~
RR tc ~~ 1
~um
2~um
)~~( 012 huuB
large mass splitting between and !1
~um2
~um
In this large & mixing scenario;
QFV branching ratio can be large!
RR tc ~~ RL tt ~~ LRR tctu ~~~~
~1
LRR ttcu ~~~~~2
02~
0 Hh2
~u
02~
0 HhLR tt ~~
~
1~u
LR tt ~~~
In our scenario "top trilinear coupling“ ( coupling) = TU is large!
coupling is large!
)~~( 012 huuB
02
~~ Htt RL
021
~~ huu
In this large & mixing scenario;
QFV BR can be large!
RR tc ~~ RL tt ~~
LRR tctu ~~~~~1
1~u
01
~
tc /
RR ct ~~~
)~/~( 011 tcuB
QFV BR can be large!)~/~~( 01
0012 htchuuB
5.2 Impact of squark generation mixing on squark bosonic decays
large & mixings
RR tc ~~ RL tt ~~
large QFV BR’s & !)~~( 012 huuB )~/~( 0
11 tcuB
This can lead to large QFV effects at LHC!
• Squark decay branching ratios in our scenario:
QFV squark decay branching ratio can be very large (up to ~50%) for large mixing parameter !
QFV decay BR
uRR
23RR tc ~~
)~~( 012 huuB
)~~( 012 huuB
mixing parameterRR tc ~~
• Squark decay branching ratios in our scenario:
QFV squark decay BR can be very large simultaneously for sizable mixing parameter !
QFV decay BR
uRR
23RR tc ~~
)~/~( 011 tcuB
)~/~( 011 tcuB
mixing parameterRR tc ~~
We have obtained a similar result for dependence of QFV BR and !:
can be very large (up to ~50%) for large mixing parameter !
LR tc ~~
Lt~
Lc~
Rt~uRR
23
uRL
23
uRL
33Rc~
uRL
23
)~~( 012 huuB )~/~( 0
11 tcuB )~~( 0
12 huuB uRL
23
• Squark decay branching ratios in our scenario:
QFV squark decay BR can be very large (up to ~50%) for large mixing parameter !
QFV decay BR
uRL
23LR tc ~~ )~~( 0
12 huuB
)~~( 012 huuB
mixing parameterLR tc ~~
QFV parameters: = (227 GeV)2 = (433 GeV)2
223QM
223UM
233
22232223
/)2/( QUU
uRLMMTv
• Squark decay branching ratios in our scenario:
QFV squark decay BR can be very large simultaneously for large mixing parameter !
QFV decay BR )~/~( 011 tcuB
)~/~( 011 tcuB
LR tc ~~ uRL
23
QFV parameters: = (227 GeV)2 = (433 GeV)2
mixing parameterLR tc ~~ 233
22232223
/)2/( QUU
uRLMMTv
5.3 Impact on squark signatures at LHC
01
~~ ctg Large , , mixings RR tc ~~ RL tt ~~ LR tc ~~
Large QFV BR )~/~~( 01
0012 htchuuB
QFV squark signals with significant rate at LHC !
Gluino pair production and the QFV squark bosonic decay can lead to
QFV squark signal at LHC :
)~~()~)(~(
)~)(~()~)(~(~~
01
01
0001
01
01121
XhcctcXchtcc
XchucuXcucuXggpp
‘top-quark + 3 jets + h0 + missing-ET + beam-jets‘
Example of QFV squark signal at LHC
Gluino pair production and the QFV squark bosonic decay can lead to
QFV squark signal at LHC :
)~~()~)(~(
)~)(~()~)(~(~~
01
01
0001
01
01121
XhccttXchttc
XchutuXcutuXggpp
‘2 top-quarks + 2 jets + h0 + missing-ET + beam-jets‘
Example of QFV squark signal at LHC
blbWt
‘isolated same sign dilepton + 4 jets + h0 + missing-ET + beam-jets‘
Gluino pair production and the QFV squark bosonic decay can lead to
QFV squark signature at LHC :
)~~()~)(~(
)~)(~()~)(~(~~
01
01
00001
001
01
0122
XhhccttXchtcht
XchuchuXcucuXggpp
‘2 top-quarks + 2 jets + 2 h0 + missing-ET + beam-jets‘
Example of QFV squark signal at LHC
blbWt
‘isolated same sign dilepton + 4 jets + 2 h0 + missing-ET + beam-jets‘
p pgg
c
isolated same sign dilepton
l 'l
c
bb
‘isolated same sign dilepton + 4 jets + 2 h0 + missing-ET + beam-jets‘
0h0h
h0 decay branching ratios
• B(h0 tau- tau+) = 9.1%
• B(h0 b b_bar) = 57.3%
• B(h0 photon photon) = 0.52%
• B(h0 W W*) = 22.7%
• B(h0 Z Z*) = 2.5%
h0 is SM-like in our scenario!
QFV signal rates at LHC
QFV squark signal rates can be significant
at LHC(14 TeV)!
In our scenario;
- gluino prod. cross section is significant:
~ 80 fb at LHC(14 TeV)!
- can be large (~ 25 %)!
We can expect copious production of
from gluino prod. and decays at LHC(14 TeV)!
)~~( Xggpp )/~~( 2 tcugB
2~u
Our analyses suggest the following:
•One should take into account the possibility of significant
contributions from QFV decays in the squark and gluino
search at LHC.
• Moreover, one should also include QFV squark parameters
(i.e. squark–generation mixing parameters) in the determination
of the basic SUSY parameters at LHC.
6. Impact on squark & gluino search at LHC
7. Conclusion• We have studied the effect of squark generation mixing on squark and gluino
production and decays at LHC in the MSSM with focus on mixing between 2nd
and 3rd generation squarks.
• Taking into account the constraints from B-physics experiments, we have shown that
various regions in parameter space exist where decays of squarks and/or gluinos
into flavour violating final states can have large branching ratios of up to ~ 50%.
Here we have considered both fermionic and bosonic final states.
• Rates of the corresponding signals, e.g. ‘ + beam-jets’ , and
‘ + beam-jets’ can be significant at LHC(14 TeV).
• We conclude that the inclusion of flavour mixing effects can be important for the
search of squarks and gluinos and the determination of the MSSM parameters
at LHC.
misTEccttpp
misTEhhccttpp 00