Miguel A. Sanchis-Lozano*

4th Int Workshop on Heavy Quarkonium June 27-30 BNL

Miguel A. Sanchis-Lozano IFIC-Valencia

1

Miguel A. Sanchis-Lozano*

Department of Theoretical Physics & IFICUniversity of Valencia – CSIC

Spain

Limits/Signals of a light non-standard Limits/Signals of a light non-standard Higgs boson in Upsilon leptonic decaysHiggs boson in Upsilon leptonic decays††

*email: [email protected]

†† Special thanks to the CLEO Collaborationparticularly to Jean Duboscq for many discussions



2

Testing Lepton Universality

Channel: * BF[e+e-] BF[μ+ μ-] BF[+-] R/l

(1S) 2.52 ± 0.08 % 2.54 ± 0.13 % 0.01 ± 0.06

(1S) 2.49 ± 0.07 % 2.54 ± 0.13 % 0.02 ± 0.05

(2S) 2.01 ± 0.16 % 2.11 ± 0.15 % 0.05 ± 0.11

(2S) 2.03 ± 0.09 % 2.11 ± 0.15 % 0.04 ± 0.06

(3S) 1.92 ± 0.24 % 2.55 ± 0.24 % 0.33 ± 0.18

(3S) 2.39 ± 0.12 % 2.55 ± 0.24 % 0.07 ± 0.09

*Obtained from recent but in some cases preliminary CLEO data Statistical and systematic errors are summed in quadrature

1)(

)(/

B

BB

BBR

em

nS s

Lepton Universality in Upsilon decays implies

<R/l > =0

BF( e+ e-) =BF( + -) = BF( + -)



3

Testing Lepton Universality

Channel: * BF[e+e-] BF[μ+ μ-] BF[+-] R/l

(1S) 2.38 ± 0.11 % 2.61 ± 0.13 % 0.10 ± 0.07

(1S) 2.48 ± 0.06 % 2.61 ± 0.13 % 0.05 ± 0.06

(2S) 1.97 ± 0.11 % 2.11 ± 0.15 % 0.07 ± 0.09

(2S) 1.93 ± 0.17 % 2.11 ± 0.15 % 0.09 ± 0.12

(3S) 1.92 ± 0.24 % 2.55 ± 0.24 % 0.33 ± 0.18

(3S) 2.18 ± 0.21 % 2.55 ± 0.24 % 0.17 ± 0.15

*Obtained from recent but preliminary CLEO data and already existing PDG values Statistical and systematic errors are summed in quadrature

1)(

)(/

B

BB

BBR

em

nS s

Lepton Universality in Upsilon decays implies

<R/l > =0

BF( e+ e-) =BF( + -) = BF( + -)



4

Lepton Universality Breaking? LU

R/l

0.0 0.1 0.2

R/e(1S)

R/(1S)

R/e(2S)

R/(2S)

R/e(3S)

R/(3S)

0.3

Hypothesis test

Null hypothesis: lepton universality predicting <R/l> = 0

Alternative hypothesis: <R/l> > 0

From this set of data Lepton Universality can be

rejectedat a level of significance of

0.5 % (corresponding to a 2.8 sigma

effect)

0.4

preliminary



5

(Hidden) systematic errors?There could be hidden systematic errors in the extraction of the muonic and tauonic branching fractions from experimental data, e.g. use is made of lepton universality asan intermediate step

had/ B

BBB

BB

B

BB

ee

1

~

~31

~/

BBB

BB

BB

Bee

1

~~

31

~/

The muonic branching fraction would be overestimated if

The tauonic branching fraction would be underestimated if

had/ B

Defining:

Defining:

BB~~

BB~~

hep-ex/0409027hep-ex/9409004

Besides phase space disfavors the tauonic decay mode by 1% (Van-Royen Weisskopf formula)

Bee = B= B

Bee = B= B

In the opposite direction !



6

Searching for a light non-standard Higgs

nS s A0( )

Such NP contribution would be unwittingly ascribed tothe leptonic branching fraction (photon undetected!*)

actually only for the tauonic decay mode

A leptonic mass dependence of the decay width wouldbreak lepton universality. Contribution from the SM should be negligible

22 offunction decreasing (smoothly)

2/12

2

22)(

M/with

)41)(21(M

)0(4

mx

xxR

Qx

nb

em

Van Royen-Weisskopf formula

Notice that a light non-standard Higgs

boson has not been excluded by LEP direct searches for a broad range of

model parameters in different scenarios

n=1,2,3 and A0 stands for a light (possibly CP-odd) Higgs particle

-

+A0

s

Prior M1 transition

Prejudice against a light Higgs?

b intermediatestate or bb continuumb

b

Tree-level NP processtheoretically very simple!

Our conjecture to interpret a possible Lepton Universality breakdown

photon unseen! *

Key ideas:

*Missing energy in events (neutrinos from tauonic decays) but photons can be searched for in data recorded on tape However, they likely would not be monochromatic!

nS s b

(*) ( A0* )



7

,,,,,,)(tan 5

0

int ebsdddidmvA

L fff

,,,,,,)(cot 5

0

int efff tcuuuium

vA

L

A large value of tanβ would imply a large A0 coupling to the bottom quark but a small coupling

(i.e. small cot β) to the charm quark. Therefore, in the quest for NP effects we will focus on bottomonium decays and spectroscopy but not on charmonium as this is the case (see PDG)

tanβ stands for the 2 Higgs VEVs ratio <Hu>/<Hd> and v=246 GeV

*The MSSM is a particular 2HDM(II) realization CPC: 1 CP-odd Higgs (A0) 2 CP-even Higgses h0 =-1sin +2cos H0= 1sin -2cos 2 charged H At tree level:

In a general 2HDM:

Coupling of fermions and the CP-odd Higgs A0

In a 2HDM of type II

CPV MSSM

Two-Higgs Doublet Model (II)*

Higgs sector

00ˆ,ˆ

d

dd

u

uu H

HH

H

HH

At one-loop level, MSSM with complex parameters is not CP conserving

The three Higgs neutral bosons mix together and the resulting three physical mass eigenstatesH1, H2 and H3 (MH1 < MH2 < MH3) have mixed parities

Higgs couplings to the Z boson would vary: the H1ZZ coupling can be significantly suppressed

raising the possibility of a relatively light H1 boson having evaded detection at LEP [hep-ph/0211467]

2W

2A

2H

MMM o

245

2A

2H 2

1MM 0 v

333 10)7.08.2()'(10)8.03.7()'(10)28.041.7()'( BBeeB



8

Light Higgs windows at LEP (2HDM(II))

hep-ex/0408097hep-ex/0408097

Excluded (mA,mh) region independent of the CP even Higgs mixing angle , from flavor-independent and b-tagging searches at LEP interpreted according to a 2HDM(II)

Excluded regions in the (mA,tanβ) plane for different choices of . In the MSSM -/2 0 ; in a general 2HDM(II) -/2 /2



9

Light Higgs windows at LEP (MSSM CPV)hep-ex/0406057hep-ex/0406057

hep-ex/0406057

CPX MSSM 95% exclusion areas using scans with different values of arg (At,b). The region excluded by Yukawa searches, Z-width

constraints or decay independent searches is shown in red

CPX MSSM 95% exclusion areas using scans with differentvalues of the top mass

Diagram illustrating the effective coupling of a Higgs mass eigenstate H1 to the Z. Only the CP-even admixture h and H couple to Z while the CP-odd A does not: hence

the coupling of the H1 is reduced wrt a CPC scenario.



10

Next-to-Minimal Supersymmetric Standard Model (NMSSM)

Higgs sector in the NMSSM: (seven) 2 neutral CP-odd Higgs bosons (A1,2)

3 neutral CP-even Higgs bosons (H1,2,3 )

2 charged Higgs bosons (H±)

A new singlet superfield is added to the Higgs sector: In general more extra SM singlets can be added: hep-ph/0405244

/, where

3)(ˆ

3)ˆˆ(ˆ 33

Sxx

h.c.SAHHSAVSHHSW dusoftduHiggs

The μ-problem of the MSSM would be solved by introducing in the superpotential the term

SH

HH

H

HH

d

dd

u

uu

ˆ,ˆ,ˆ00

Breaks explicitly the PQ symmetrySpontaneous breaking of the PQ symmetry

The A1 would be the lightest Higgs:

Favored decay mode: H1,2 A1 A1

hard to detect at the LHC [hep-ph/0406215]

A

3M2

A1

sMSMS1 A sinA cosA AA

Coupling of A1 to down type fermions:

xAxA

x

x

m

A

Af

2,

tanv

cos

tancos,v

222

22

2

[hep-ph/0404220]

If к =0 → U(1) Peccei-Quinn symmetry

Spontaneous breaking NGB (massless), an “axion” (+QCD anomaly) ruled out experimentally

If the PQ symmetry is not exact but explicitly broken provides a mass to the (pseudo) NGB leading to a light CP-odd scalar for small кIf λ and zero → U(1)R symmetry; if U(1)R slightly broken → a light pseudoscalar Higgs boson too



11

Contribution from the “continuum”

222

32)(

)2(

1

M32

1

dmdmllAll

Let us perform a perturbative calculation of the contribution from the “continuum”, i.e.

without formation of intermediate bound states assuming the Higgs boson off-shell

222

A

2A

43

42

1MM

Mlog

64tan

0

0

mv

MR

Numerical es

timates

Rather large values of tanβ ( 50)are needed to obtain R ~ 10%

MM,1

MM

Mlog

144

tan)0()( 0

0

0

A2

22A

2A

43

42

mv

RnS n

where the square amplitude is

and the decay width (leading term):

nS A0 ( + -)

Higgs boson on-shell

2

2A

2

22

M

M1

8tanM 0

vR

Wilczek formula

R=0.1tanβ ~ 15

Somewhat higher values of tanβin a relativistic treatment

bb

One should also consider:

Experimentally excluded region +”nothing”: BF < 1.3 x10-5 for MA0 < 5 GeV

[CLEO, PRD 51, 2053 (1995)]

2/1A2

220 )41(M

8tan

]A[ 0

x

vm B(A0 + -) 1

even for moderate tanβ

YAMM 0

0AY MM

MY-MAº=0.25 GeV

A0

l+

l-



12

Intermediate bound states

)()()( bbss BBB

2b

32b

M1

bs 341

)( b

mkQI

B

nS s b ( A0* (H1*) l+ l-)

422A

22

42

n2/124

bb )MM(2

tan)0()41(3)(

0b

v

Rxmm

2

2

42

342b

M)21(8

tan

m

vx

kmR

b

%101)(

ee

s

B

BR

tanβ ≥ 30 ΔM=0.25 GeV

We consider that a prior magnetic dipole transition of the Upsilon yields an intermediate bound state, subsequently annihilating into a lepton pair via A0 (or H1)-exchange

A cascade decay formula should apply:

The NP contribution would almost saturate the b decay rate even for moderate tanβ if M is not too large !

M1 transition probability

Numerical estimates

In a 2HDM(II)

43s

*b 1010)( P

b0 MMM

A Mass difference betweenthe Higgs boson and the b

Intermediate real 0-+ state

Allowed and hindered M1 transitions between

(3S), (2S) and (1S) states

________Y(3S) -------------b(3S)

________Y(2S)-------------b(2S)

________Y(1S)

-------------b(1S)

600 MeV

1000 MeV

)CL%95(%27.0

))'(η)(())(( b

SnnSBnSB

100 MeV

1)( b B

CLEO limit

MeV100)1( bbMM S



13

nS b0 ( h0 + -) n=2,3 ( H1 + -)

003.0002.0)()()( b0b0s BBB s

CP-even Higgs bosonCP-even Higgs boson

R 0.1tanβ ~ 15

422A

22

42'2/322b

0 )MM(8

tan)0()41(27)(

00

v

Rxmm

b

nb

Using ΔM=0.25 GeV, tanβ 15 → B(b0+ -) ≈ 6% and B( b0) ≈ 3-6% (PDG) as reference values, we get:

h0-mediated decay width under the assumption that sin(-β) ≈ 0 i.e. non-decoupling limit: h0 couplings deviate maximally from SMwhereas the H0 becomes a SM-like Higgs:

Cascade decay via Cascade decay via b0 b0 resonancesresonances

Numerical

estimates

4

2'2

0

0

0 M

)0(96

b

b

nsb

Rgg

Normalizing the above partial width to

Again only for the tauonic mode would the NP contribution be significantleading to lepton universality breaking!

setting s(M) = 0.15 and |R’n(0)|2 = 1.5 GeV5 keV3200

b

Decay channel only open for (2S) and (3S) resonances

Intermediate real 0++ state

)cos(tan)sin(cos

sin- :coupling /bb -h -

A CP-even Higgs boson can couple to an intermediate b0 resonance after a E1 transition of the



14

Possible spectroscopic consequences in bottomonium

Searches for b states at CLEO: No signal found!

• A0-b mixing? Mass shift yielding larger hyperfine splitting than

expected in the SM (i.e. more than ~100 MeV).

Higgs Yukawa couplings to fermions can be affected too, allowing quite large tanβ for special Higgs mass values

hep-ex/0207057

• Broad b states? Widths of order 50 MeV could be expected even for moderate values of tanβ

hep-ex/0207057 hep-ex/0207057

tanβ(LEP)hep-ex/0111010

“Is there any point to which you would wish to draw my attention?”“To the curious incident of the dog in the night-time”

“The dog did nothing in the night-time”“That was the curious incident”, remarked Sherlock Holmes

from “Silver Blaze” by Sir A.C.D.

Most theoretical models are ruled out !

The search for b states would

be a way of hunting

a light non-standard Higgs!

If b decay happens to besaturated by the

A0-mediated channelb A0* + -

A quite broad b expected!

Drees and Hikasa, PRD 41, 1547 (1990)

MeV5)(

)(5

5

cb

cs

bs

c

b

m

m

m

m

SM:

Also implying lower rates for other decay modes:

b J/ψ J/ψ(3S) ’bo b(1S)



15

Conclusions

Keep also an eye on the related issues:

● g-2 muon anomaly (which might require a CP-odd light Higgs contribution in a two-loop calculation) ● Search for Bs,d , decays (GIM mechanism can spoil the expected signal hep-ph/0209306)

● Searches for dark matter in the universe (McElrath, this workshop)

If lepton universality is found to be (slightly) broken in Upsilon decays, the simplest explanation would require a light non-standard mediated Higgs contribution (subsequent to a M1 transition of the resonance) unwittingly ascribed to the tauonic decay mode

If not, those light Higgs mass windows could be closed! Possibly too hard a job for the LHC

● Reasonable values of tanβ in a 2HDM(II) are needed to yield R/l of order 10%

● Different scenarios beyond the SM could explain such a LU breaking

● Further exp tests suggested: - search for soft (non-monochromatic) photons in the

+- sample of Upsilon decays

- seek after the b resonance!

- polarization studies of the tau…

Based on: hep-ph/0510374hep-ph/0503266hep-ph/0407320hep-ph/0307313hep-ph/0210364hep-ph/0206156

Relevance of a Super B Factory running on the region !!!Complementary to other searches at the LHC

Avec de l’audace, on peut tout entreprendre, on ne peut pas tout faireNapoléon Ier



16

Light Neutralino Dark Matter

• Neutralino dark matter is generally assumed to be relatively heavy, with a mass near the electroweak scale

• It has been shown, however, that the claims of dark matter detection made by DAMA can be reconciled with null results of CDMS II if one considers a WIMP lighter than approximately 10 GeV [hep-ph/0504010]

• A very light CP-odd Higgs can make possible a very light neutralino to annihilate via such a light Higgs boson exchange [hep-ph/0509024]

leading to low-enery positrons which would generate the 511 keV gamma-ray emission observed from the galactic bulge by INTEGRAL/SPI experiment

positronsmuonspions~~ 000 A



17

g-2 muon anomaly in a 2HDM(II)

hep-ph/0302111

The 2σ allowed regions in the (mA,mh) plane due to the constraints of a and Rb for tanβ=40. The blue region is where the total 2 is less than 4 while the yellow region is where the total 2 is less than the 2 (SM)

One.loop vertex correction

Two-loop vertex correction

h,A

h,A

f



18

MSSM (CPV)• The Higgs potential is explicitly CP-conserving if all Higgs potential parameters are

real. Otherwise, CP is explicitly violated• CP-violation is generated by loop effects involving top and bottom squarks • CP-violation can modify drastically the tree-level couplings of the Higgs particles to

fermions and gauge bosons• The CP parities of the neutral Higgs bosons may be mixed by radiative effects

involving the third generation of squarks• Under CP violation, the mass of the CP-odd Higgs scalar is no longer an eigenvalue but rather an entry in a general 3 x 3 neutral Higgs mass matrix

MSP2 mt

4 Im(At) / v2 MSUSY2

where is the mixing parameter of the two Higgs superfields

At denotes the soft SUSY-breaking trilinear coupling of the Higgs bosons to top squarks

v=246 GeV VEV of the Higgs

MSUSY stands for the common SUSY-breaking scale



19

Intermediate bound states

)()()( bbss BBB

2b

32b

M1

bs 341

)( b

mkIQ

B

nS s b ( A0* (H1*) l+ l-)

422A

22

42

n2/124

bb )MM(2

tan)0()41(3)(

0b

v

Rxmm

We consider that a prior magnetic dipole transition of the Upsilon yields an intermediate bound state, subsequently annihilating into a lepton pair via A0 (or H1)-exchange

A cascade decay formula applies:

The NP contribution would almost saturate the b decay rate even for moderate tanβ if M is not too large !

M1 transition probability

Numerical es

timates

In a 2HDM(II)

53s

*b 1010)( P

ΔM (GeV)

hep-ph/0407320

Range of tanβ fora given M value

b0 MMM

A Mass difference betweenthe Higgs boson and the b

Intermediate real 0-+ state

Allowed and hindered M1 transitions between (3S), (2S) and (1S)

))'(η)(())(( b SnnSBnSB

________Y(3S) -------------b(3S)

________Y(2S)-------------b(2S)

________Y(1S)

-------------b(1S)

600 MeV

1000 MeV

Documents

Miguel A. Sanchis-Lozano*