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Resonance scan

by nakulphy
Tags: breit wigner, resonance, scan
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nakulphy
#1
Mar18-14, 12:40 PM
P: 10
what is breit wigner distribution function ?
it is used in resonance scan means it decides the no of events for any specific channel. i am also giving the link of the paper where i found this
http://pos.sissa.it/archive/conferen...io2012_018.pdf

please help me out

thank you
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Einj
#2
Mar19-14, 10:14 AM
P: 305
The Breit-Wigner distribution is a particular factor appearing in the expression for the scattering cross section when this scattering happens via an intermediate particle. Consider for example the scattering [itex]a+b\to A\to X+Y[/itex]. The expression for the cross section is given by:
$$
\frac{d\sigma(a+b\to X+Y)}{d\vec pd s_X}=\frac{d\Gamma(A\to X)}{\Gamma(A\to all)}\frac{d\sigma(a+b\to A+Y)}{d\vec pd s_A} W(s_A)\sqrt{\frac{\vec p^2+m_A^2}{\vec p^2+s_A}},
$$
where the Breit-Wigner distribution is given by:
$$
W(s_A)=\frac{1}{\pi}\frac{m_A\Gamma}{(s_A-m_A^2)^2+m_A^2\Gamma^2}.
$$
As you can see, such a distribution gives an enhancement of the cross section (i.e. of the number of particles produced) when [itex]s_A\simeq m_A^2[/itex], provided that the width [itex]\Gamma[/itex] of the intermediate particle is not too large.
nakulphy
#3
Mar19-14, 11:27 AM
P: 10
thank you very much
i will try to understand this and also try to correlate with the paper and will come back to you soon.

thank you

Einj
#4
Mar19-14, 11:38 AM
P: 305
Resonance scan

The paper itself is about the exotic hadron X(3872). It is a perfect example of resonance. Namely it doesn't appear as a final state of the reaction but as an intermediate particle. It is, for example, produced ad LHC via the reaction: p+p -> X(3872) -> D0 + antiD0*. As you can see this is exactly as the reaction I showed you before.
nakulphy
#5
Apr3-14, 12:42 AM
P: 10
thank you very much.

can you please suggest me the reference book to study this ? actually I understood the things but still I want to understand in more detail.

thank you

Nakul Soni
Einj
#6
Apr3-14, 07:22 AM
P: 305
Do you mean the X(3872) or resonances in general?
nakulphy
#7
Apr3-14, 07:30 AM
P: 10
for the basic of Breit-Wigner and the distribution function.
Einj
#8
Apr3-14, 07:58 AM
P: 305
One of the best books is De Wit - Field theory in particle physics. In particular the chapter on decay rates


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