Little Higgs models often feature spontaneously broken extra global symmetries, which must also b... more Little Higgs models often feature spontaneously broken extra global symmetries, which must also be explicitly broken in order to avoid massless Goldstone modes in the spectrum. We show that a possible conflict with collective symmetry breaking then implies light modes coupled to the Higgs boson, leading to interesting phenomenology. Moreover, spontaneous CP violation is quite generic in such cases, as the explicit breaking may be used to stabilize physical CP odd phases in the vacuum. We demonstrate this in an SU(2)×SU(2)×U(1) variant of the Littlest Higgs, as well as in an original SU(6)/SO(6) model. We show that even a very small explicit breaking may lead to large phases, resulting in new sources of CP violation in this class of models.
We present a model with dark matter in an anomaly-mediated supersymmetry breaking hidden sector w... more We present a model with dark matter in an anomaly-mediated supersymmetry breaking hidden sector with a U(1)×U(1) gauge symmetry. The symmetries of the model stabilize the dark matter and forbid the introduction of new mass parameters. As a result, the thermal relic density is completely determined by the gravitino mass and dimensionless couplings. Assuming non-hierarchical couplings, the thermal relic density is Ω X ∼ 0.1, independent of the dark matter's mass and interaction strength, realizing the WIMPless miracle. The model has several striking features. For particle physics, stability of the dark matter is completely consistent with R-parity violation in the visible sector, with implications for superpartner collider signatures; also the thermal relic's mass may be ∼ 10 GeV or lighter, which is of interest given recent direct detection results. Interesting astrophysical signatures are dark matter self-interactions through a long-range force, and massless hidden photons and fermions that contribute to the number of relativistic degrees of freedom at BBN and CMB. The latter are particularly interesting, given current indications for extra degrees of freedom and near future results from the Planck observatory.
We discuss a new class of low energy supersymmetric models in which the Higgs sector includes a s... more We discuss a new class of low energy supersymmetric models in which the Higgs sector includes a single doublet, for example Hu, but not H d. Chiral gauge anomalies are canceled against new electroweak-charged states. We discuss the main challenges in building such models, and present several models where these issues are addressed. The resulting phenomenology can be distinguished from that of the MSSM in a number of ways, most notably in physics related to down-type quarks and charged leptons. As a first step toward a chiral Higgs sector, we discuss the scenario of an inert H d doublet. We show that a UV completion of such model naturally includes dark matter with novel, flavorful couplings to SM quarks.
The flavor puzzle of the Standard Model is explained in split fermion models by having the fermio... more The flavor puzzle of the Standard Model is explained in split fermion models by having the fermions localized and separated in an extra dimension. Many of these models assume a certain profile for the Higgs VEV, usually uniform, or confined to a brane, without providing a dynamical realization for it. By studying the effect of the coupling between the Higgs and the localizer fields, we obtain these scenarios as results, rather than ansätze. Moreover, we discuss other profiles and show that they are phenomenologically viable.
The observed flavor structure of the standard model arises naturally in "split fermion" models wh... more The observed flavor structure of the standard model arises naturally in "split fermion" models which localize fermions at different places in an extra dimension. It has, until now, been assumed that the bulk masses for such fermions can be chosen to be flavor diagonal simultaneously at every point in the extra dimension, with all the flavor violation coming from the Yukawa couplings to the Higgs. We consider the more natural possibility in which the bulk masses cannot be simultaneously diagonalized, that is, that they are twisted in flavor space. We show that, in general, this does not disturb the natural generation of hierarchies in the flavor parameters. Moreover, it is conceivable that all the flavor mixing and CP-violation in the standard model may come only from twisting, with the five-dimensional Yukawa couplings taken to be universal.
We present a class of warped extra dimensional models whose flavor violating interactions are muc... more We present a class of warped extra dimensional models whose flavor violating interactions are much suppressed compared to the usual anarchic case due to flavor alignment. Such suppression can be achieved in models where part of the global flavor symmetry is gauged in the bulk and broken in a controlled manner. We show that the bulk masses can be aligned with the down type Yukawa couplings by an appropriate choice of bulk flavon field representations and TeV brane dynamics. This alignment could reduce the flavor violating effects to levels which allow for a Kaluza-Klein scale as low as 2-3 TeV, making the model observable at the LHC. However, the up-type Yukawa couplings on the IR brane, which are bounded from below by recent bounds on CP violation in the D system, induce flavor misalignment radiatively. Off-diagonal down-type Yukawa couplings and kinetic mixings for the down quarks are both consequences of this effect. These radiative Yukawa corrections can be reduced by raising the flavon VEV on the IR brane (at the price of some moderate tuning), or by extending the Higgs sector. The flavor changing effects from the radiatively induced Yukawa mixing terms are at around the current upper experimental bounds. We also show the generic bounds on UV-brane induced flavor violating effects, and comment on possible additional flavor violations from bulk flavor gauge bosons and the bulk Yukawa scalars.
We formulate the necessary conditions for a scalar potential to exhibit spontaneous CP violation.... more We formulate the necessary conditions for a scalar potential to exhibit spontaneous CP violation. Associated with each complex scalar field is a U(1) symmetry that may be explicitly broken by terms in the scalar potential (called spurions). In order for CP-odd phases in the vacuum to be physical, these phases must be related to spontaneously broken U(1) generators that are also
The weak phase γ can be determined using untagged B 0 → DK S or B s → Dφ, Dη (′) decays. In the p... more The weak phase γ can be determined using untagged B 0 → DK S or B s → Dφ, Dη (′) decays. In the past, the small lifetime difference y ≡ ∆Γ/(2Γ) has been neglected in B 0 , while the CP violating parameter ǫ ≡ 1 − |q/p| 2 has been neglected in both B 0-B 0 and B s-B s mixing. We estimate the effect of neglecting y and ǫ. We find that in D decays to flavor states this introduces a systematic error, which is enhanced by a large ratio of Cabibbo-allowed to doubly Cabibbo-suppressed D decay amplitudes.
We propose an efficient method to explore models which which produce like-sign tops at the LHC, u... more We propose an efficient method to explore models which which produce like-sign tops at the LHC, using the total charge asymmetry of single lepton events instead of like-sign dileptons. As an example, the method is implemented on a Z Model, which can explain the top pair forwardbackward asymmetry at Tevatron. We show that a large region of the parameter space of this model can be reached using the existing data set at the LHC.
We discuss a new class of low energy supersymmetric models in which the Higgs sector includes a s... more We discuss a new class of low energy supersymmetric models in which the Higgs sector includes a single doublet, for example Hu, but not H d. Chiral gauge anomalies are canceled against new electroweak-charged states. We discuss the main challenges in building such models, and present several models where these issues are addressed. The resulting phenomenology can be distinguished from that of the MSSM in a number of ways, most notably in physics related to down-type quarks and charged leptons. As a first step toward a chiral Higgs sector, we discuss the scenario of an inert H d doublet. We show that a UV completion of such model naturally includes dark matter with novel, flavorful couplings to SM quarks.
We perform an extensive survey of nonstandard Higgs decays that are consistent with the 125 GeV H... more We perform an extensive survey of nonstandard Higgs decays that are consistent with the 125 GeV Higgs-like resonance. Our aim is to motivate a large set of new experimental analyses on the existing and forthcoming data from the Large Hadron Collider (LHC). The explicit search for exotic Higgs decays presents a largely untapped discovery opportunity for the LHC collaborations, as such decays may be easily missed by other searches. We emphasize that the Higgs is uniquely sensitive to the potential existence of new weakly coupled particles and provide a unified discussion of a large class of both simplified and complete models that give rise to characteristic patterns of exotic Higgs decays. We assess the status of exotic Higgs decays after LHC run I. In many cases we are able to set new nontrivial constraints by reinterpreting existing experimental analyses. We point out that improvements are possible with dedicated analyses and perform some preliminary collider studies. We prioritize the analyses according to their theoretical motivation and their experimental feasibility. This document is accompanied by a Web site that will be continuously updated with further information [http://exotichiggs.physics .sunysb.edu].
We explore the coupling of the strange quark to the state of mass close to 126 GeV recently obser... more We explore the coupling of the strange quark to the state of mass close to 126 GeV recently observed by the ATLAS and CMS experiments at the LHC. An enhanced coupling relative to the expectations for a SM Higgs has the effect of increasing both the inclusive production cross section and the partial decay width into jets. For very large modifications, the latter dominates and the net rate into non-jet decay modes such as diphotons is suppressed, with the result that one can use observations of the diphoton decay mode to place an upper limit on the strange quark coupling. We find that the current observations of the diphoton decay mode imply that the coupling of the new resonance to strange quarks can be at most ∼ 50 times the SM expectation at the 95% C.L., if one assumes at most a O(1) modification of the coupling to gluons.
Little Higgs models often feature spontaneously broken extra global symmetries, which must also b... more Little Higgs models often feature spontaneously broken extra global symmetries, which must also be explicitly broken in order to avoid massless Goldstone modes in the spectrum. We show that a possible conflict with collective symmetry breaking then implies light modes coupled to the Higgs boson, leading to interesting phenomenology. Moreover, spontaneous CP violation is quite generic in such cases, as the explicit breaking may be used to stabilize physical CP odd phases in the vacuum. We demonstrate this in an SU(2)×SU(2)×U(1) variant of the Littlest Higgs, as well as in an original SU(6)/SO(6) model. We show that even a very small explicit breaking may lead to large phases, resulting in new sources of CP violation in this class of models.
The Higgs-like signal observed at the LHC could be due to several mass degenerate resonances. We ... more The Higgs-like signal observed at the LHC could be due to several mass degenerate resonances. We show that the number of resonances is related to the rank of a "production and decay" matrix, R if. Each entry in this matrix contains the observed rate in a particular production mode i and final state f. In the case of N non-interfering resonances, the rank of R is, at most, N. If interference plays a role, the maximum rank is generically N 2 , or with a universal phase, N (N + 1)/2. As an illustration we use the present experimental data to constrain the rank of the corresponding matrix. We estimate the LHC reach of probing two and three resonances under various speculations on future measurements and uncertainties.
Little Higgs models often feature spontaneously broken extra global symmetries, which must also b... more Little Higgs models often feature spontaneously broken extra global symmetries, which must also be explicitly broken in order to avoid massless Goldstone modes in the spectrum. We show that a possible conflict with collective symmetry breaking then implies light modes coupled to the Higgs boson, leading to interesting phenomenology. Moreover, spontaneous CP violation is quite generic in such cases, as the explicit breaking may be used to stabilize physical CP odd phases in the vacuum. We demonstrate this in an SU(2)×SU(2)×U(1) variant of the Littlest Higgs, as well as in an original SU(6)/SO(6) model. We show that even a very small explicit breaking may lead to large phases, resulting in new sources of CP violation in this class of models.
We present a model with dark matter in an anomaly-mediated supersymmetry breaking hidden sector w... more We present a model with dark matter in an anomaly-mediated supersymmetry breaking hidden sector with a U(1)×U(1) gauge symmetry. The symmetries of the model stabilize the dark matter and forbid the introduction of new mass parameters. As a result, the thermal relic density is completely determined by the gravitino mass and dimensionless couplings. Assuming non-hierarchical couplings, the thermal relic density is Ω X ∼ 0.1, independent of the dark matter's mass and interaction strength, realizing the WIMPless miracle. The model has several striking features. For particle physics, stability of the dark matter is completely consistent with R-parity violation in the visible sector, with implications for superpartner collider signatures; also the thermal relic's mass may be ∼ 10 GeV or lighter, which is of interest given recent direct detection results. Interesting astrophysical signatures are dark matter self-interactions through a long-range force, and massless hidden photons and fermions that contribute to the number of relativistic degrees of freedom at BBN and CMB. The latter are particularly interesting, given current indications for extra degrees of freedom and near future results from the Planck observatory.
We discuss a new class of low energy supersymmetric models in which the Higgs sector includes a s... more We discuss a new class of low energy supersymmetric models in which the Higgs sector includes a single doublet, for example Hu, but not H d. Chiral gauge anomalies are canceled against new electroweak-charged states. We discuss the main challenges in building such models, and present several models where these issues are addressed. The resulting phenomenology can be distinguished from that of the MSSM in a number of ways, most notably in physics related to down-type quarks and charged leptons. As a first step toward a chiral Higgs sector, we discuss the scenario of an inert H d doublet. We show that a UV completion of such model naturally includes dark matter with novel, flavorful couplings to SM quarks.
The flavor puzzle of the Standard Model is explained in split fermion models by having the fermio... more The flavor puzzle of the Standard Model is explained in split fermion models by having the fermions localized and separated in an extra dimension. Many of these models assume a certain profile for the Higgs VEV, usually uniform, or confined to a brane, without providing a dynamical realization for it. By studying the effect of the coupling between the Higgs and the localizer fields, we obtain these scenarios as results, rather than ansätze. Moreover, we discuss other profiles and show that they are phenomenologically viable.
The observed flavor structure of the standard model arises naturally in "split fermion" models wh... more The observed flavor structure of the standard model arises naturally in "split fermion" models which localize fermions at different places in an extra dimension. It has, until now, been assumed that the bulk masses for such fermions can be chosen to be flavor diagonal simultaneously at every point in the extra dimension, with all the flavor violation coming from the Yukawa couplings to the Higgs. We consider the more natural possibility in which the bulk masses cannot be simultaneously diagonalized, that is, that they are twisted in flavor space. We show that, in general, this does not disturb the natural generation of hierarchies in the flavor parameters. Moreover, it is conceivable that all the flavor mixing and CP-violation in the standard model may come only from twisting, with the five-dimensional Yukawa couplings taken to be universal.
We present a class of warped extra dimensional models whose flavor violating interactions are muc... more We present a class of warped extra dimensional models whose flavor violating interactions are much suppressed compared to the usual anarchic case due to flavor alignment. Such suppression can be achieved in models where part of the global flavor symmetry is gauged in the bulk and broken in a controlled manner. We show that the bulk masses can be aligned with the down type Yukawa couplings by an appropriate choice of bulk flavon field representations and TeV brane dynamics. This alignment could reduce the flavor violating effects to levels which allow for a Kaluza-Klein scale as low as 2-3 TeV, making the model observable at the LHC. However, the up-type Yukawa couplings on the IR brane, which are bounded from below by recent bounds on CP violation in the D system, induce flavor misalignment radiatively. Off-diagonal down-type Yukawa couplings and kinetic mixings for the down quarks are both consequences of this effect. These radiative Yukawa corrections can be reduced by raising the flavon VEV on the IR brane (at the price of some moderate tuning), or by extending the Higgs sector. The flavor changing effects from the radiatively induced Yukawa mixing terms are at around the current upper experimental bounds. We also show the generic bounds on UV-brane induced flavor violating effects, and comment on possible additional flavor violations from bulk flavor gauge bosons and the bulk Yukawa scalars.
We formulate the necessary conditions for a scalar potential to exhibit spontaneous CP violation.... more We formulate the necessary conditions for a scalar potential to exhibit spontaneous CP violation. Associated with each complex scalar field is a U(1) symmetry that may be explicitly broken by terms in the scalar potential (called spurions). In order for CP-odd phases in the vacuum to be physical, these phases must be related to spontaneously broken U(1) generators that are also
The weak phase γ can be determined using untagged B 0 → DK S or B s → Dφ, Dη (′) decays. In the p... more The weak phase γ can be determined using untagged B 0 → DK S or B s → Dφ, Dη (′) decays. In the past, the small lifetime difference y ≡ ∆Γ/(2Γ) has been neglected in B 0 , while the CP violating parameter ǫ ≡ 1 − |q/p| 2 has been neglected in both B 0-B 0 and B s-B s mixing. We estimate the effect of neglecting y and ǫ. We find that in D decays to flavor states this introduces a systematic error, which is enhanced by a large ratio of Cabibbo-allowed to doubly Cabibbo-suppressed D decay amplitudes.
We propose an efficient method to explore models which which produce like-sign tops at the LHC, u... more We propose an efficient method to explore models which which produce like-sign tops at the LHC, using the total charge asymmetry of single lepton events instead of like-sign dileptons. As an example, the method is implemented on a Z Model, which can explain the top pair forwardbackward asymmetry at Tevatron. We show that a large region of the parameter space of this model can be reached using the existing data set at the LHC.
We discuss a new class of low energy supersymmetric models in which the Higgs sector includes a s... more We discuss a new class of low energy supersymmetric models in which the Higgs sector includes a single doublet, for example Hu, but not H d. Chiral gauge anomalies are canceled against new electroweak-charged states. We discuss the main challenges in building such models, and present several models where these issues are addressed. The resulting phenomenology can be distinguished from that of the MSSM in a number of ways, most notably in physics related to down-type quarks and charged leptons. As a first step toward a chiral Higgs sector, we discuss the scenario of an inert H d doublet. We show that a UV completion of such model naturally includes dark matter with novel, flavorful couplings to SM quarks.
We perform an extensive survey of nonstandard Higgs decays that are consistent with the 125 GeV H... more We perform an extensive survey of nonstandard Higgs decays that are consistent with the 125 GeV Higgs-like resonance. Our aim is to motivate a large set of new experimental analyses on the existing and forthcoming data from the Large Hadron Collider (LHC). The explicit search for exotic Higgs decays presents a largely untapped discovery opportunity for the LHC collaborations, as such decays may be easily missed by other searches. We emphasize that the Higgs is uniquely sensitive to the potential existence of new weakly coupled particles and provide a unified discussion of a large class of both simplified and complete models that give rise to characteristic patterns of exotic Higgs decays. We assess the status of exotic Higgs decays after LHC run I. In many cases we are able to set new nontrivial constraints by reinterpreting existing experimental analyses. We point out that improvements are possible with dedicated analyses and perform some preliminary collider studies. We prioritize the analyses according to their theoretical motivation and their experimental feasibility. This document is accompanied by a Web site that will be continuously updated with further information [http://exotichiggs.physics .sunysb.edu].
We explore the coupling of the strange quark to the state of mass close to 126 GeV recently obser... more We explore the coupling of the strange quark to the state of mass close to 126 GeV recently observed by the ATLAS and CMS experiments at the LHC. An enhanced coupling relative to the expectations for a SM Higgs has the effect of increasing both the inclusive production cross section and the partial decay width into jets. For very large modifications, the latter dominates and the net rate into non-jet decay modes such as diphotons is suppressed, with the result that one can use observations of the diphoton decay mode to place an upper limit on the strange quark coupling. We find that the current observations of the diphoton decay mode imply that the coupling of the new resonance to strange quarks can be at most ∼ 50 times the SM expectation at the 95% C.L., if one assumes at most a O(1) modification of the coupling to gluons.
Little Higgs models often feature spontaneously broken extra global symmetries, which must also b... more Little Higgs models often feature spontaneously broken extra global symmetries, which must also be explicitly broken in order to avoid massless Goldstone modes in the spectrum. We show that a possible conflict with collective symmetry breaking then implies light modes coupled to the Higgs boson, leading to interesting phenomenology. Moreover, spontaneous CP violation is quite generic in such cases, as the explicit breaking may be used to stabilize physical CP odd phases in the vacuum. We demonstrate this in an SU(2)×SU(2)×U(1) variant of the Littlest Higgs, as well as in an original SU(6)/SO(6) model. We show that even a very small explicit breaking may lead to large phases, resulting in new sources of CP violation in this class of models.
The Higgs-like signal observed at the LHC could be due to several mass degenerate resonances. We ... more The Higgs-like signal observed at the LHC could be due to several mass degenerate resonances. We show that the number of resonances is related to the rank of a "production and decay" matrix, R if. Each entry in this matrix contains the observed rate in a particular production mode i and final state f. In the case of N non-interfering resonances, the rank of R is, at most, N. If interference plays a role, the maximum rank is generically N 2 , or with a universal phase, N (N + 1)/2. As an illustration we use the present experimental data to constrain the rank of the corresponding matrix. We estimate the LHC reach of probing two and three resonances under various speculations on future measurements and uncertainties.
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Papers by Ze'ev Surujon