117037063
New limits on $\mathbf{\tan\beta}$ for 2HDMs with $\mathbf{Z_2}$ symmetry
In two-Higgs-doublet models with exact $Z_2$ symmetry, putting $m_h \simeq 125$ GeV at the alignment limit, the following limits on the heavy scalar masses are obtained from the conditions of unitarity and stability of the scalar potential: $m_H,~m_A,~m_{H^+} < 1$ TeV and $1/8 <\tan\beta <8$. The constraints from $b \to s \gamma$ and neutral meson mass differences, when superimposed on the unitarity constraints, put a tighter lower limit on $\tan\beta$ depending on $m_{H^+}$. It has also been shown that larger values of $\tan\beta$ can be allowed by introducing soft breaking term in the potential at the expense of a correlation between $m_H$ and the soft breaking parameter.
119194609
Feasibility of light scalars in a class of two-Higgs-doublet models and their decay signatures
We demonstrate that light charged and extra neutral scalars in the (100-200) GeV mass range pass the potentially dangerous flavor constraints in a particular class of two-Higgs-doublet model which has appropriately suppressed flavor-changing neutral currents at tree level. We study their decay branching ratios into various fermionic final states and comment on the possibility of their detection in the collider experiments. We also remark on how their trademark decay signatures can be used to discriminate them from the light nonstandard scalars predicted in other two-Higgs-doublet models.
56110441
Modified Higgs couplings and unitarity violation
Prompted by the recent observation of a Higgs-like particle at the CERN Large Hadron Collider (LHC), we investigate a quantitative correlation between possible departures of the gauge and Yukawa couplings of this particle from their Standard Model expectations and the scale of unitarity violation in the processes $WW \to WW$ and $t\bar t \to WW$.
119230166
Nondecoupling of charged scalars in Higgs decay to two photons and symmetries of the scalar potential
A large class of two- and three-Higgs-doublet models with discrete symmetries has been employed in the literature to address various aspects of flavor physics. We analyze how the precision measurement of the Higgs to diphoton signal strength would severely constrain these scenarios due to the nondecoupling behavior of the charged scalars, to the extent that in the presence of exact discrete symmetry, the number of additional noninert scalar doublets can be constrained no matter how heavy the nonstandard scalars are. We demonstrate that if the scalar potential is endowed with appropriate global continuous symmetries together with soft breaking parameters, decoupling can be achieved thanks to the unitarity constraints on the mass-square differences of the heavy scalars.
118444203
Scalar sector properties of two-Higgs-doublet models with a global U(1) symmetry
A bstractWe analyze the scalar sector properties of a general class of two-Higgs-doublet models which has a global U(1) symmetry in the quartic terms. We find constraints on the parameters of the potential from the considerations of unitarity of scattering amplitudes, the global stability of the potential and the ρ-parameter. We concentrate on the spectrum of the non-standard scalar masses in the decoupling limit which is preferred by the Higgs data at the LHC. We exhibit charged-Higgs induced contributions to the diphoton decay width of the 125 GeV Higgs boson and its correlation with the corresponding Zγ width.
119111711
Analysis of an extended scalar sector with S3 symmetry
We investigate the scalar potential of a general S3-symmetric three-Higgs-doublet model. The outcome of our analysis does not depend on the fermionic sector of the model. We identify a decoupling limit for the scalar spectrum of this scenario. In view of the recent LHC Higgs data, we show our numerical results only in the decoupling limit. Unitarity and stability of the scalar potential demand that many new scalars must be lurking below 1 TeV. We provide numerical predictions for h→γγ and h→Zγ signal strengths, which can be used to falsify the theory.
122669506
High voltage characteristic of large area cathode pad chambers for muon spectrometer of ALICE
AbstractLarge area Cathode Pad Chambers (CPC) with inner and outer radii of 23.7 cm and 117 cm respectively have been fabricated and tested for 2nd Tracking station of Muon Spectrometer of ALICE.The active area of this detector has a radiation length of less than 2 % and the frames are fabricated with Peek GF-30. The anode wire plane consists of 474 anode wires of which 53 % have lengths greater than 1 meter. The separation between the wire plane and the grounded cathode plane is 2.5 mm. The high voltage behaviour of the chamber have been tested under two situations.
With no support below the wires to reduce sagging of long wires.With a G10 strip-support whose dimension is 950 mm × 2 mm × 2.4 mm.
 The High Voltage (HV) tests show that a better stability is achieved when the strip support is implemented. Therefore this solution has been adopted for operation in ALICE.
123139058
Conformal freedom and Kasner and Belinskii models
In this paper we show, in the context of the quantum mechanical principle of uncertainty, that if conformal freedom has a quantum character then Kasner and Belinskii models have a status quantum-mechanically different from some models, i.e. Robertson - Walker, Bianchi type I (some forms) and Bianchi type III models.
119115082
Quantum quench across a zero temperature holographic superfluid transition
A bstractWe study quantum quench in a holographic model of a zero temperature insulator-superfluid transition. The model is a modification of that of arXiv:0911.0962 and involves a self-coupled complex scalar field, Einstein gravity with a negative cosmological constant, and Maxwell field with one of the spatial directions compact. In a suitable regime of parameters, the scalar field can be treated as a probe field whose backreaction to both the metric and the gauge field can be ignored. We show that when the chemical potential of the dual field theory lies between two critical values, the equilibrium background geometry is an AdS soliton with a constant gauge field, while the complex scalar condenses leading to broken symmetry. We then turn on a time dependent source for the order parameter which interpolates between constant values and crosses the order-disorder critical point. In the critical region adiabaticity breaks down, but for a small rate of change of the source v there is a new small-v expansion in fractional powers of v. The resulting critical dynamics is dominated by a zero mode of the bulk field. To lowest order in this small-v expansion, the order parameter satisfies a time dependent Landau-Ginsburg equation which has z = 2, but non-dissipative. These predictions are verified by explicit numerical solutions of the bulk equations of motion.
118390596
Quantum quench and double trace couplings
A bstractWe consider quantum quench by a time dependent double trace coupling in a strongly coupled large N field theory which has a gravity dual via the AdS/CFT correspondence. The bulk theory contains a self coupled neutral scalar field coupled to gravity with negative cosmological constant. We study the scalar dynamics in the probe approximation in two backgrounds: AdS soliton and AdS black brane. In either case we find that in equilibrium there is a critical phase transition at a negative value of the double trace coupling κ below which the scalar condenses. For a slowly varying homogeneous time dependent coupling crossing the critical point, we show that the dynamics in the critical region is dominated by a single mode of the bulk field. This mode satisfies a Landau-Ginsburg equation with a time dependent mass, and leads to Kibble Zurek type scaling behavior. For the AdS soliton the system is non-dissipative and has z = 1, while for the black brane one has dissipative z = 2 dynamics. We also discuss the features of a holographic model which would describe the non-equilibrium dynamics around quantum critical points with arbitrary dynamical critical exponent z and correlation length exponent ν. These analytical results are supported by direct numerical solutions.
118578316
Chaos around holographic Regge trajectories
A bstractUsing methods of Hamiltonian dynamical systems, we show analytically that a dynamical system connected to the classical spinning string solution holographically dual to the principal Regge trajectory is non-integrable. The Regge trajectories themselves form an integrable island in the total phase space of the dynamical system. Our argument applies to any gravity background dual to confining field theories and we verify it explicitly in various supergravity backgrounds: Klebanov-Strassler, Maldacena-Núñez, Witten QCD and the AdS soliton. Having established non-integrability for this general class of supergravity backgrounds, we show explicitly by direct computation of the Poincaré sections and the largest Lyapunov exponent, that such strings have chaotic motion.