scholarly journals THE NA62 EXPERIMENT AT CERN AND THE MEASUREMENT OF THE ULTRA-RARE DECAY K+-π+v¯v

2013 ◽  
Vol 53 (A) ◽  
pp. 814-816
Author(s):  
Antonella Antonelli
Keyword(s):  
Rare Decay ◽  
Large Angle ◽  
Branching Ratio ◽  
Particle Identification ◽  
Lead Glass ◽  
Good Resolution ◽  
Kaon Decays ◽  
Level Zero ◽  
Zero Rate ◽  
Kaon Momentum

The NA62 experiment at CERN aims at the very challenging task of measuring with 10% relative error the Branching Ratio of the ultra-rare decay of the K<sup>+</sup> into π<sup>+</sup> ν¯ν which is expected to occur only in about 8 out of 10<sup>11</sup> Kaon decays. This will be achieved by means of an intense hadron beam, an accurate kinematical reconstruction and a redundant veto system for identifying and suppressing all spurious events. Good resolution on the missing mass in the decay is achieved using a high-resolution beam tracker to measure the kaon momentum and with a spectrometer equipped with straw tubes operating in vacuum. Hermetic veto (up to 50 mrad) of the photon from π<sup>0</sup> decays is achieved with a combination of large angle veto (with a creative reuse of the old OPAL lead glass blocks), the NA48 liquid Krypton calorimeter and two small angle calorimeters to cover the angle down to zero. The identification of the muons and the consequent veto is performed by a fast hodoscope plane (used in the first level of the trigger to reduce the rate) and by a 17 meter, neon-filled RICH counter which is able to separate pions and muons in the momentum interval between 15 and 35 GeV. Particle identification in the beam (K<sup>+</sup> separation) is achieved with an H2 differential Cherenkov counter. The trigger for the experiment is based on a multilevel structure with a first level implemented in the readout boards and with the subsequent level done in the software. The aim is to reduce the 10MHz level zero rate to a few kHz sent to the CERN computing centre. Studies are underway to use GPU boards in some key point of the trigger system to improve the performance.<p> </p>

scholarly journals Recent NA48/2 results on rare kaon decays

2019 ◽  
Vol 206 ◽  
pp. 05001
Author(s):  
Dmitry Madigozhin
Keyword(s):  
Decay Rate ◽  
Effective Mass ◽  
Precise Measurement ◽  
Rare Decay ◽  
Branching Ratio ◽  
Charged Kaon ◽  
Kaon Decays ◽  
Model Independent

NA48/2 results contributing to ChPT testing are presented. A sample of 1663 events of the rare decay $ K^ \pm \to \mu ^ \pm ve^ + e^ - $ has been selected with a minimum e +e −effective mass of 140 MeV. The measured model independent decay rate is in agreement with ChPT predictions. The branching ratio of the $ K^ \pm \to \mu ^ \pm ve^ + e^ - $ decay, never observed so far, has been obtained from a sample of about 5000 candidates with less than 6% background, also in agreement with ChPT predictions. In addition, a most precise measurement of the charged kaon semileptonic formfactors has been obtained from 4.4 million Ke3 and 2.3 million Kµ3 events collected in 2004.

scholarly journals SPECTATOR EFFECTS IN THE DECAY B→Kγγ

2005 ◽  
Vol 20 (17) ◽  
pp. 4079-4084 ◽  
Author(s):  
A. YU. IGNATIEV ◽  
G. C. JOSHI ◽  
B. H. J. MCKELLAR
Keyword(s):  
Standard Model ◽  
Decay Mode ◽  
Short Distance ◽  
Enhancement Factor ◽  
Rare Decay ◽  
Branching Ratio ◽  
The Spectator

We report the results of the first computation related to the study of the spectator effects in the rare decay mode B→Kγγ within the framework of Standard Model. It is found that the account of these effects results in the enhancement factor for the short-distance reducible contribution to the branching ratio.

scholarly journals Probing new physics with $B^0_s\to\mu^+\mu^-$: Status and perspectives

2014 ◽  
Vol 29 (21) ◽  
pp. 1444004 ◽  
Author(s):  
Robert Fleischer
Keyword(s):  
Standard Model ◽  
Decay Width ◽  
Rare Decay ◽  
Branching Ratio ◽  
New Physics ◽  
High Luminosity ◽  
Width Difference ◽  
Rate Asymmetry ◽  
The Standard Model ◽  
Meson System

The rare decay [Formula: see text] plays a key role for the testing of the Standard Model. It is pointed out that the sizable decay width difference ΔΓsof the Bs-meson system affects this channel in a subtle way. As a consequence, its calculated Standard Model branching ratio has to be upscaled by about 10%. Moreover, the sizable ΔΓsmakes a new observable through the effective [Formula: see text] lifetime accessible, which probes New Physics in a way complementary to the branching ratio and adds an exciting new topic to the agenda for the high-luminosity upgrade of the LHC. Further probes of New Physics are offered by a CP-violating rate asymmetry. Correlations between these observables and the [Formula: see text] branching ratio are illustrated for specific models of New Physics.

SEARCH FOR KL→π0μ±e∓

2001 ◽  
Vol 16 (supp01b) ◽  
pp. 651-653
Author(s):  
◽  
ANGELA BELLAVANCE
Keyword(s):  
Branching Ratio ◽  
Kaon Decays ◽  
Lepton Flavor ◽  
Ratio Limit

The KTeV experiment (Kaons at the TeVatron) at Fermilab studies CP violating and other rare kaon decays, including the search for the lepton-flavor violating mode KL→π0μ±e∓. KTeV has obtained a new, preliminary branching ratio limit of BR(KL→π0μ±e∓)<4.40×10-10.

scholarly journals EFFECT OF BOTH Z AND Z′-MEDIATED FLAVOR-CHANGING NEUTRAL CURRENTS ON Bs →τ+τ- DECAY

2012 ◽  
Vol 27 (31) ◽  
pp. 1250184 ◽  
Author(s):  
S. SAHOO ◽  
D. BANERJEE ◽  
M. KUMAR ◽  
S. MOHANTY
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
Rare Decay ◽  
Charge Asymmetry ◽  
Branching Ratio ◽  
New Physics ◽  
Neutral Currents ◽  
Flavor Changing ◽  
Potential Source ◽  
Flavor Changing Neutral Currents

In recent years, Bs →τ+τ- rare decay has attracted a lot of attention since it is very sensitive to the structure of standard model (SM) and potential source of new physics beyond SM. In this paper, we study the effect of both Z and Z′-mediated flavor-changing neutral currents on the Bs →τ+τ- decay. We find the branching ratio B(Bs→τ+τ-) is enhanced relative to SM prediction, which would help to explain the recently observed CP-violation from like-sign dimuon charge asymmetry in the B system.

Investigation of boundary structure of copper phthalocyanine crystal grains in resolving crystallographic planes

1978 ◽  
Vol 36 (1) ◽  
pp. 432-433
Author(s):  
G.I. Natsvlishvili
Keyword(s):  
Copper Phthalocyanine ◽  
Large Angle ◽  
Boundary Structure ◽  
Good Resolution ◽  
Dislocation Boundary ◽  
Perfect Lattice ◽  
Elastic Fields ◽  
Disorientation Angle ◽  
Crystallographic Planes ◽  
The Right

Deformed crystals of copper phtalocyanine have been investigated. The crystals were deformed in the process of grinding. Large angle grain boundaries with good resolution of dislocations and crystallographic planes (001) have been detected in the electron microscope JEM-100 C.Fig1 shows the grain dislocation boundary with disorientation angles ≈ll.5°.Attention should be paid to the asymmetry of the boundary. The boundary for the left side grain is almost parallel to the plane (100), while the atomic planes of the right side grain break off at the boundary at a distance of ≈65 Å from each other. The measured Burgers vector (b=12.6 Å) and the distance between the dislocations in the wall correspond to the measured disorientation angle.If the image of the region of ‘perfect’ lattice is projected from the same negative under the photographic enlarger on the printed photograph, it will be easy to see that the elastic fields of dislocation forming the boundary given in fig. 1 are also asymmetric.

scholarly journals TESTS OF CHPT WITH ${\rm K}_{{\rm e}4}^{+-}$ AND ${\rm K}_{{\rm e}4}^{00}$ DECAYS AT THE NA48/2 EXPERIMENT AT CERN

2014 ◽  
Vol 35 ◽  
pp. 1460458
Author(s):  
MAURO RAGGI
Keyword(s):  
Form Factor ◽  
Percent Level ◽  
Branching Ratio ◽  
Form Factors ◽  
Low Energy ◽  
P Wave ◽  
Isospin Symmetry ◽  
Charged Kaon ◽  
Kaon Decays ◽  
Isospin Symmetry Breaking

The NA48/2 experiment has collected the largest samples to date of semi-leptonic charged kaon decays in the [Formula: see text] (K± → π+π-e±ν) and [Formula: see text] (K± → π0π0e±ν) modes. From 1.1 million [Formula: see text] decays, form factors in the S- and P-wave have been extensively studied. Branching ratio and form factors have been measured at unprecedented precision. From ~ 66000 [Formula: see text] decays, preliminary values of the Branching ratio and form factor have been obtained at a percent level precision. The comparison of Branching ratio and form factor values in both Ke4 modes sheds new light on isospin symmetry breaking effects. Form factor measurements are major inputs to the study of low energy QCD and are powerful tests of Chiral Perturbation Theory predictions.

scholarly journals Latest results on rare kaon decays from the NA48/2 experiment @CERN

2020 ◽  
Vol 35 (36) ◽  
pp. 2044019
Author(s):  
N. Molokanova
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Precise Measurement ◽  
Branching Ratio ◽  
Form Factors ◽  
Charged Kaon ◽  
Chiral Perturbation ◽  
Kaon Decays ◽  
Kinematic Space

The NA48/2 experiment at CERN reports the first observation of the [Formula: see text] decay from an exposure of [Formula: see text] charged kaon decays recorded in 2003–2004. A sample of 4919 candidates with 4.9% background contamination allows the determination of the branching ratio in the full kinematic region. The study of the kinematic space shows evidence for a structure-dependent contribution in agreement with predictions based on chiral perturbation theory. Several [Formula: see text]- and [Formula: see text]-violating asymmetries are also evaluated. The most precise measurement of the charged kaon semi-leptonic form factors obtained by NA48/2 with 4.4 million [Formula: see text] and 2.3 million [Formula: see text] events collected in 2004 will also be presented.

scholarly journals RESULTS ON CP VIOLATION FROM THE NA48 EXPERIMENT AT CERN

2002 ◽  
Vol 17 (22) ◽  
pp. 3012-3025
Author(s):  
◽  
LYDIA ICONOMIDOU-FAYARD
Keyword(s):  
Cp Violation ◽  
Rare Decay ◽  
Branching Ratio ◽  
Current Status

In this article the current status and latest results of the NA48 experiment at CERN are given. We present in more details the analysis performed for the Re(ε′/ε) measurement with the combined statistics accumulated during the 1998 and 1999 data periods. Reviewing the NA48 rare decay program, we select to underline the new results on the branching ratio and the aV factor for the decay K L → π0γγ and the K L → π+ π- e+ e- CP violating decay.

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